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Sample records for growth cone regulates

  1. Mechanochemical regulation of growth cone motility

    PubMed Central

    Kerstein, Patrick C.; Nichol IV, Robert H.; Gomez, Timothy M.

    2015-01-01

    Neuronal growth cones are exquisite sensory-motor machines capable of transducing features contacted in their local extracellular environment into guided process extension during development. Extensive research has shown that chemical ligands activate cell surface receptors on growth cones leading to intracellular signals that direct cytoskeletal changes. However, the environment also provides mechanical support for growth cone adhesion and traction forces that stabilize leading edge protrusions. Interestingly, recent work suggests that both the mechanical properties of the environment and mechanical forces generated within growth cones influence axon guidance. In this review we discuss novel molecular mechanisms involved in growth cone force production and detection, and speculate how these processes may be necessary for the development of proper neuronal morphogenesis. PMID:26217175

  2. ERM proteins regulate growth cone responses to Sema3A

    PubMed Central

    Mintz, C. David; Carcea, Ioana; McNickle, Daniel G.; Dickson, Tracey C.; Ge, Yongchao; Salton, Stephen R.J.; Benson, Deanna L.

    2008-01-01

    Axonal growth cones initiate and sustain directed growth in response to cues in their environment. A variety of events such as receptor internalization, kinase activation, and actin rearrangement can be stimulated by guidance cues and are essential for mediating targeted growth cone behavior. Surprisingly little is known about how such disparate actions are coordinated. Our data suggest that ezrin, radixin, and moesin (ERMs), a family of highly homologous, multifunctional proteins may be able to coordinate growth cone responses to the guidance cue, Sema3A. We show that active ERMs concentrate asymmetrically in neocortical growth cones, are rapidly and transiently inactivated by Sema3A, and are required for Sema3A-mediated growth cone collapse and guidance. The FERM domain of active ERMs regulates internalization of the Sema3A receptor, Npn1 and its co-receptor, L1CAM, while the ERM C-terminal domain binds and caps F-actin. Our data support a model in which ERMs can coordinate membrane and actin dynamics in response to Sema3A. PMID:18651636

  3. Coupled local translation and degradation regulate growth cone collapse

    PubMed Central

    Deglincerti, Alessia; Colak, Dilek; Hengst, Ulrich; Liu, Yaobin; Xu, Guoqiang; Jaffrey, Samie R.

    2015-01-01

    Local translation mediates axonal responses to Semaphorin3A (Sema3A) and other guidance cues. However, only a subset of the axonal proteome is locally synthesized, while most proteins are trafficked from the soma. The reason why only specific proteins are locally synthesized is unknown. Here we show that local protein synthesis and degradation are linked events in growth cones. We find that growth cones exhibit high levels of ubiquitination and that local signaling pathways trigger the ubiquitination and degradation of RhoA, a mediator of Sema3A-induced growth cone collapse. Inhibition of RhoA degradation is sufficient to remove the protein-synthesis requirement for Sema3A-induced growth cone collapse. In addition to RhoA, we find that locally translated proteins are the main targets of the ubiquitin-proteasome system in growth cones. Thus, local protein degradation is a major feature of growth cones and creates a requirement for local translation to replenish proteins needed to maintain growth cone responses. PMID:25901863

  4. A Novel Function for p53: Regulation of Growth Cone Motility through Interaction with Rho Kinase

    PubMed Central

    Qin, Qingyu; Baudry, Michel; Liao, Guanghong; Noniyev, Albert; Galeano, James; Bi, Xiaoning

    2009-01-01

    The transcription factor p53 suppresses tumorgenesis by regulating cell proliferation and migration. We investigated whether p53 could also control cell motility in postmitotic neurons. P53 isoforms recognized by phospho-p53-specific (at Ser15) or “mutant” conformation specific antibodies were highly and specifically expressed in axons and axonal growth cones in primary hippocampal neurons. Inhibition of p53 function by inhibitors, siRNAs, or by dominant negative forms, induced axonal growth cone collapse, whereas p53 over-expression led to larger growth cones. Furthermore, deletion of the p53 nuclear export signal blocked its axonal distribution and induced growth cone collapse. P53 inhibition-induced axonal growth cone collapse was significantly reduced by the Rho kinase (ROCK) inhibitor, Y27632. Our results reveal a new function for p53 as a critical regulator of axonal growth cone behavior by suppressing ROCK activity. PMID:19386914

  5. Subcellular Profiling Reveals Distinct and Developmentally Regulated Repertoire of Growth Cone mRNAs

    PubMed Central

    Zivraj, Krishna H.; Tung, Yi Chun Loraine; Piper, Michael; Gumy, Laura; Fawcett, James W.; Yeo, Giles S. H.; Holt, Christine E.

    2013-01-01

    Cue-directed axon guidance depends partly on local translation in growth cones. Many mRNA transcripts are known to reside in developing axons, yet little is known about their subcellular distribution or, specifically, which transcripts are in growth cones. Here laser capture microdissection (LCM) was used to isolate the growth cones of retinal ganglion cell (RGC) axons of two vertebrate species, mouse and Xenopus, coupled with unbiased genomewide microarray profiling. An unexpectedly large pool of mRNAs defined predominant pathways in protein synthesis, oxidative phosphorylation, cancer, neurological disease, and signaling. Comparative profiling of “young” (pathfinding) versus “old” (target-arriving) Xenopus growth cones revealed that the number and complexity of transcripts increases dramatically with age. Many presynaptic protein mRNAs are present exclusively in old growth cones, suggesting that functionally related sets of mRNAs are targeted to growth cones in a developmentally regulated way. Remarkably, a subset of mRNAs was significantly enriched in the growth cone compared with the axon compartment, indicating that mechanisms exist to localize mRNAs selectively to the growth cone. Furthermore, some receptor transcripts (e.g., EphB4), present exclusively in old growth cones, were equally abundant in young and old cell bodies, indicating that RNA trafficking from the soma is developmentally regulated. Our findings show that the mRNA repertoire in growth cones is regulated dynamically with age and suggest that mRNA localization is tailored to match the functional demands of the growing axon tip as it transforms into the presynaptic terminal. PMID:21084603

  6. Involvement of microtubules in the regulation of neuronal growth cone morphologic remodeling.

    PubMed

    Gallo, G

    1998-05-01

    The guidance of nerve fibers depends on the constant protrusion, movement, and retraction (i.e., remodeling) of growth cone lamellae and filopodia. We used drugs that interfere with the dynamics of microtubules to investigate the role of microtubules in the remodeling of larval amphibian spinal cord neuronal growth cones. Vinblastine (8-100 nM), taxol (10 nM), and nocodazole (330 nM) altered microtubule distributions in growth cones and decreased the percentage of lamellar perimeter undergoing remodeling, while not affecting the rates of lamellar protrusion and retraction. Also, 8-20 nM vinblastine caused temporary losses of the continuity of the originally fan-shaped lamella, resulting in two or more lamellae at the growth cone. At higher concentrations of microtubule drugs, the originally fan-shaped lamella broke up into separate smaller lamellae followed by the centrifugal displacement from the base of the growth cone and eventual collapse of the resultant lamellae. Low doses of cytochalasin B prevented the centrifugal displacement of lamellae in response to microtubule drugs. During microtubule drug-mediated loss of growth cone lamellae, some filopodia were observed to elongate to greater than normal lengths. Similarly, exposure to 20 nM vinblastine resulted in an increase in filopodial length but not filopodial number. As evidenced by DiOC6(3) staining, 8-20 nM vinblastine altered the distribution of membranous organelles within growth cones, suggesting that the effects of microtubule drugs on growth cones may be mediated in part by alterations in organelle localization. Our data show that microtubules are involved in the maintenance and regulation of lamellar and filopodial structures at the neuronal growth cone. These findings have implications for the mechanisms by which growth cones are guided during development and regeneration. PMID:9581969

  7. Integrin-linked kinase regulates oligodendrocyte cytoskeleton, growth cone, and adhesion dynamics.

    PubMed

    Michalski, John-Paul; Cummings, Sarah E; O'Meara, Ryan W; Kothary, Rashmi

    2016-02-01

    Integrin-linked kinase (ILK), a focal adhesion protein, brokers the link between cytoskeleton, cell membrane, and extracellular environment. Here, we demonstrate a role for ILK in laminin-2-mediated adhesion in primary murine oligodendrocytes (OLs) - with ILK loss leading to severe defects in process branching and outgrowth. These defects were partially recovered when the ILK-depleted OLs were instead grown on the non-integrin-activating substrate poly-l-lysine. Intriguingly, ILK loss on the neutral poly-l-lysine substrate led to swelling at the tips of OL processes, which we identified as enlarged growth cones. Employing the bloated ILK-depleted growth cones as template, we demonstrate the appearance of distinct cytoskeletal domains within OL growth cones bearing classic neuronal growth cone architecture. Further, microtubule organization was severely perturbed following ILK loss, with centripetal microtubule looping and failure to bundle occurring in a laminin-2-independent manner. Together, our work highlights differences in specific aspects of OL biology as driven by laminin-2-dependent or independent ILK governed mechanisms. We also reinforce the idea of OLs as growth cone bearing cells and describe the neuronal-like cytoskeleton therein. Finally, we demonstrate a role for ILK in OL growth cone maturation through microtubule regulation, the loss of which translates to decreased process length and myelin production capacity. We describe herein how different substrates fundamentally alter the oligodendrocyte's response to loss of integrin-linked kinase (ILK). On laminin-2 (Ln-2), ILK-depleted oligodendrocytes appear stunted and malformed, while on the non-integrin-activating substrate PLL branching and membrane formation are restored. We also reinforce the idea of oligodendrocytes as growth cone-bearing cells, detailing the growth cone's cytoskeletal architecture. Strikingly, loss of ILK on poly-l-lysine leads to growth cone swelling, the structure's size and

  8. α2-Chimaerin interacts with EphA4 and regulates EphA4-dependent growth cone collapse

    PubMed Central

    Shi, Lei; Fu, Wing-Yu; Hung, Kwok-Wang; Porchetta, Cassandra; Hall, Christine; Fu, Amy K. Y.; Ip, Nancy Y.

    2007-01-01

    EphA4-dependent growth cone collapse requires reorganization of actin cytoskeleton through coordinated activation of Rho family GTPases. Whereas various guanine exchange factors have recently been identified to be involved in EphA4-mediated regulation of Rho GTPases and growth cone collapse, the functional roles of GTPase-activating proteins in the process are largely unknown. Here we report that EphA4 interacts with α2-chimaerin through its Src homology 2 domain. Activated EphA4 induces a rapid increase of tyrosine phosphorylation of α2-chimaerin and enhances its GTPase-activating protein activity toward Rac1. More importantly, α2-chimaerin regulates the action of EphA4 in growth cone collapse through modulation of Rac1 activity. Our findings have therefore identified a new α2-chimaerin-dependent signaling mechanism through which EphA4 transduces its signals to the actin cytoskeleton and modulates growth cone morphology. PMID:17911252

  9. TRPV1 at nerve endings regulates growth cone morphology and movement through cytoskeleton reorganization.

    PubMed

    Goswami, C; Schmidt, H; Hucho, F

    2007-02-01

    While the importance of Ca(2+) channel activity in axonal path finding is established, the underlying mechanisms are not clear. Here, we show that transient receptor potential vanilloid receptor 1 (TRPV1), a member of the TRP superfamily of nonspecific ion channels, is physically and functionally present at dynamic neuronal extensions, including growth cones. These nonselective cation channels sense exogenous ligands, such as resenifera toxin, and endogenous ligands, such as N-arachidonoyl-dopamine (NADA), and affect the integrity of microtubule cytoskeleton. Using TRPV1-transiently transfected F11 cells and embryonic dorsal root ganglia explants, we show that activation of TRPV1 results in growth cone retraction, and collapse and formation of varicosities along neurites. These changes were due to TRPV1-activation-mediated disassembly of microtubules and are partly Ca(2+)-independent. Prolonged activation with very low doses (1 nM) of NADA results in shortening of neurites in the majority of isolectin B4-positive dorsal root ganglia neurones. We postulate that TRPV1 activation plays an inhibitory role in sensory neuronal extension and motility by regulating the disassembly of microtubules. This might have a role in the chronification of pain. PMID:17288556

  10. Regulation of ECM degradation and axon guidance by growth cone invadosomes

    PubMed Central

    Santiago-Medina, Miguel; Gregus, Kelly A.; Nichol, Robert H.; O'Toole, Sean M.; Gomez, Timothy M.

    2015-01-01

    Invadopodia and podosomes, collectively referred to as invadosomes, are F-actin-rich basal protrusions of cells that provide sites of attachment to and degradation of the extracellular matrix. Invadosomes promote the invasion of cells, ranging from metastatic cancer cells to immune cells, into tissue. Here, we show that neuronal growth cones form protrusions that share molecular, structural and functional characteristics of invadosomes. Growth cones from all neuron types and species examined, including a variety of human neurons, form invadosomes both in vitro and in vivo. Growth cone invadosomes contain dynamic F-actin and several actin regulatory proteins, as well as Tks5 and matrix metalloproteinases, which locally degrade the matrix. When viewed using three-dimensional super-resolution microscopy, F-actin foci often extended together with microtubules within orthogonal protrusions emanating from the growth cone central domain. Finally, inhibiting the function of Tks5 both reduced matrix degradation in vitro and disrupted motoneuron axons from exiting the spinal cord and extending into the periphery. Taken together, our results suggest that growth cones use invadosomes to target protease activity during axon guidance through tissues. PMID:25564649

  11. Regulated release of serotonin from axonal growth cones isolated from the fetal rat brain.

    PubMed

    Mercado, R; Floran, B; Hernandez, J

    1998-01-01

    In the present work we propose an hypothetical model related to a molecular recognizing system for serotonin in isolated growth cone particles. This model is supported by previous results from our laboratory plus new ones which show that growth cones release serotonin tonically and such release can be stimulated by potassium in a calcium-dependent manner. The present results, together with other author's data, suggest a physiological basis for the putative role of serotonin as a trophic factor during nervous system development. PMID:9460708

  12. Nerve growth factor stimulates axon outgrowth through negative regulation of growth cone actomyosin restraint of microtubule advance

    PubMed Central

    Turney, Stephen G.; Ahmed, Mostafa; Chandrasekar, Indra; Wysolmerski, Robert B.; Goeckeler, Zoe M.; Rioux, Robert M.; Whitesides, George M.; Bridgman, Paul C.

    2016-01-01

    Nerve growth factor (NGF) promotes growth, differentiation, and survival of sensory neurons in the mammalian nervous system. Little is known about how NGF elicits faster axon outgrowth or how growth cones integrate and transform signal input to motor output. Using cultured mouse dorsal root ganglion neurons, we found that myosin II (MII) is required for NGF to stimulate faster axon outgrowth. From experiments inducing loss or gain of function of MII, specific MII isoforms, and vinculin-dependent adhesion-cytoskeletal coupling, we determined that NGF causes decreased vinculin-dependent actomyosin restraint of microtubule advance. Inhibition of MII blocked NGF stimulation, indicating the central role of restraint in directed outgrowth. The restraint consists of myosin IIB- and IIA-dependent processes: retrograde actin network flow and transverse actin bundling, respectively. The processes differentially contribute on laminin-1 and fibronectin due to selective actin tethering to adhesions. On laminin-1, NGF induced greater vinculin-dependent adhesion–cytoskeletal coupling, which slowed retrograde actin network flow (i.e., it regulated the molecular clutch). On fibronectin, NGF caused inactivation of myosin IIA, which negatively regulated actin bundling. On both substrates, the result was the same: NGF-induced weakening of MII-dependent restraint led to dynamic microtubules entering the actin-rich periphery more frequently, giving rise to faster elongation. PMID:26631553

  13. Membrane proteins of the nerve growth cone and their developmental regulation

    SciTech Connect

    Simkowitz, P.; Ellis, L.; Pfenninger, K.H.

    1989-03-01

    The membrane polypeptides of growth cone fragments (growth cone particles, GCPs) isolated from fetal rat brain by subcellular fractionation have been analyzed in further detail. The major polypeptides of salt-washed GCP membranes detected by 1-dimensional gel electrophoresis resolve in 2-dimensional gels as a spot of 52 kDa that comigrates with beta-tubulin and reacts with anti-beta-tubulin; a 46 kDa, pl 4.3, polypeptide (pp46) that has no equivalent in the soluble fraction and is identical to one of the GCP's major phosphoproteins and to GAP43; a spot of 42 kDa that comigrates with actin; and a species of 34 kDa (p34) without soluble equivalent. The prominent 38 kDa doublet identified in 1-dimensional gels is difficult to resolve in 2-dimensional gels. The major phosphoproteins pp80ac, pp46, and pp40, as well as p34 partition into the oil phase of Triton X-114 extracts, suggesting that they are integral membrane proteins, at least in our experimental conditions. The properties of pp46 reported here are in conflict with the highly hydrophilic amino acid sequence predicted for GAP43/B50/F1. Growth-cone and presynaptic membrane proteins are compared as follows. After eye injection of 35S-methionine, GCPs and synaptosomes are isolated from the target areas of optic nerve of fetal and adult rats, respectively. Polypeptides are separated by 1- and 2-dimensional gel electrophoresis and the radiolabeled species identified fluorographically. The comparison of labeled GCP and synaptosome polypeptides shows that all 5 major Coomassie blue-stained polypeptides of GCP membranes (52, 46, 42, 38, 34 kDa) are intensely labeled after eye injection. However, in synaptosomes, these polypeptides are weakly labeled if at all; instead, an intensely labeled polypeptide of 28 kDa, and several additional species not seen in GCPs, have appeared.

  14. D1-type dopamine receptors inhibit growth cone motility in cultured retina neurons: evidence that neurotransmitters act as morphogenic growth regulators in the developing central nervous system.

    PubMed Central

    Lankford, K L; DeMello, F G; Klein, W L

    1988-01-01

    Precedent exists for the early development and subsequent down-regulation of neurotransmitter receptor systems in the vertebrate central nervous system, but the function of such embryonic receptors has not been established. Here we show that stimulation of early-developing dopamine receptors in avian retina cells greatly inhibits the motility of neuronal growth cones. Neurons from embryonic chicken retinas were cultured in low-density monolayers, and their growth cones were observed with phase-contrast or video-enhanced-contrast-differential-interference-contrast (VEC-DIC) microscopy. Approximately 25% of the neurons responded to micromolar dopamine with a rapid reduction in filopodial activity followed by a flattening of growth cones and retraction of neurites. The response occurred at all ages examined (embryonic day-8 retinal neurons cultured on polylysine-coated coverslips for 1-7 days), although neurite retraction was greatest in younger cultures. Effects of dopamine on growth cone function could be reversed by haloperidol or (+)-SCH 23390, whereas forskolin elicited a response similar to dopamine; these data show the response was receptor-mediated, acting through a D1-type system, and are consistent with the use of cAMP as a second messenger. The experiments provide strong support for the hypothesis that neurotransmitters, besides mediating transynaptic signaling in the adult, may have a role in neuronal differentiation as growth regulators. Images PMID:3380807

  15. D1-type dopamine receptors inhibit growth cone motility in cultured retina neurons: evidence that neurotransmitters act as morphogenic growth regulators in the developing central nervous system.

    PubMed Central

    Lankford, K L; DeMello, F G; Klein, W L

    1988-01-01

    Precedent exists for the early development and subsequent down-regulation of neurotransmitter receptor systems in the vertebrate central nervous system, but the function of such embryonic receptors has not been established. Here we show that stimulation of early-developing dopamine receptors in avian retina cells greatly inhibits the motility of neuronal growth cones. Neurons from embryonic chicken retinas were cultured in low-density monolayers, and their growth cones were observed with phase-contrast or video-enhanced-contrast-differential-interference-contrast (VEC-DIC) microscopy. Approximately 25% of the neurons responded to micromolar dopamine with a rapid reduction in filopodial activity followed by a flattening of growth cones and retraction of neurites. The response occurred at all ages examined (embryonic day-8 retinal neurons cultured on polylysine-coated coverslips for 1-7 days), although neurite retraction was greatest in younger cultures. Effects of dopamine on growth cone function could be reversed by haloperidol or (+)-SCH 23390, whereas forskolin elicited a response similar to dopamine; these data show the response was receptor-mediated, acting through a D1-type system, and are consistent with the use of cAMP as a second messenger. The experiments provide strong support for the hypothesis that neurotransmitters, besides mediating transynaptic signaling in the adult, may have a role in neuronal differentiation as growth regulators. Images PMID:3357895

  16. RNA-binding proteins and translational regulation in axons and growth cones

    PubMed Central

    Hörnberg, Hanna; Holt, Christine

    2013-01-01

    RNA localization and regulation play an important role in the developing and adult nervous system. In navigating axons, extrinsic cues can elicit rapid local protein synthesis that mediates directional or morphological responses. The mRNA repertoire in axons is large and dynamically changing, yet studies suggest that only a subset of these mRNAs are translated after cue stimulation, suggesting the need for a high level of translational regulation. Here, we review the role of RNA-binding proteins (RBPs) as local regulators of translation in developing axons. We focus on their role in growth, guidance, and synapse formation, and discuss the mechanisms by which they regulate translation in axons. PMID:23734093

  17. Optogenetic control of PIP3: PIP3 is sufficient to induce the actin-based active part of growth cones and is regulated via endocytosis.

    PubMed

    Kakumoto, Toshiyuki; Nakata, Takao

    2013-01-01

    Phosphatidylinositol-3,4,5-trisphosphate (PIP3) is highly regulated in a spatiotemporal manner and plays multiple roles in individual cells. However, the local dynamics and primary functions of PIP3 in developing neurons remain unclear because of a lack of techniques for manipulating PIP3 spatiotemporally. We addressed this issue by combining optogenetic control and observation of endogenous PIP3 signaling. Endogenous PIP3 was abundant in actin-rich structures such as growth cones and "waves", and PIP3-rich plasma membranes moved actively within growth cones. To study the role of PIP3 in developing neurons, we developed a PI3K photoswitch that can induce production of PIP3 at specific locations upon blue light exposure. We succeeded in producing PIP3 locally in mouse hippocampal neurons. Local PIP3 elevation at neurite tips did not induce neurite elongation, but it was sufficient to induce the formation of filopodia and lamellipodia. Interestingly, ectopic PIP3 elevation alone activated membranes to form actin-based structures whose behavior was similar to that of growth-cone-like "waves". We also found that endocytosis regulates effective PIP3 concentration at plasma membranes. These results revealed the local dynamics and primary functions of PIP3, providing fundamental information about PIP3 signaling in neurons. PMID:23951027

  18. EMA: a developmentally regulated cell-surface glycoprotein of CNS neurons that is concentrated at the leading edge of growth cones.

    PubMed

    Baumrind, N L; Parkinson, D; Wayne, D B; Heuser, J E; Pearlman, A L

    1992-08-01

    To identify cell-surface molecules that mediate interactions between neurons and their environment during neural development, we used monoclonal antibody techniques to define a developmentally regulated antigen in the central nervous system of the mouse. The antibody we produced (2A1) immunolabels cells throughout the central nervous system; we analyzed its distribution in the developing cerebral cortex, where it is expressed on cells very soon after they complete mitosis and leave the periventricular proliferative zone. Expression continues into adult life. The antibody also labels the epithelium of the choroid plexus and the renal proximal tubules, but does not label neurons of the peripheral nervous system in the dorsal root ganglia. In dissociated cell culture of embryonic cerebral cortex, 2A1 labels the surface of neurons but not glia. Immunolabeling of neurons in tissue culture is particularly prominent on the edge of growth cones, including filopodia and the leading edge of lamellipodia, when observed with either immunofluorescence or freeze-etch immunoelectron microscopy. Immunopurification with 2A1 of a CHAPS-extracted membrane preparation from brains of neonatal mice produces a broad (32-36 kD) electrophoretic band and a less prominent 70 kD band that are sensitive to N-glycosidase but not endoglycosidase H. Thus the 2A1 antibody recognizes a developmentally regulated, neuronal cell surface glycoprotein (or glycoproteins) with complex N-linked oligosaccharide side chains. We have termed the glycoprotein antigen EMA because of its prominence on the edge membrane of growth cones. EMA is similar to the M6 antigen (Lagenaur et al: J. Neurobiol. 23:71-88, 1992) in apparent molecular weight, distribution in tissue sections, and immunoreactivity on Western blots, suggesting that the two antigens are similar or identical. Expression of EMA is a very early manifestation of neuronal differentiation; its distribution on growth cones suggests a role in mediating the

  19. Division of labor in the growth cone by DSCR1.

    PubMed

    Catlett, Timothy S; Gomez, Timothy M

    2016-05-23

    Local protein synthesis directs growth cone turning of nascent axons, but mechanisms governing this process within compact, largely autonomous microenvironments remain poorly understood. In this issue, Wang et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201510107) demonstrate that the calcineurin regulator Down syndrome critical region 1 protein modulates both basal neurite outgrowth and growth cone turning. PMID:27216257

  20. Actin Dynamics in Growth Cone Motility and Navigation

    PubMed Central

    Gomez, Timothy M.; Letourneau, Paul C.

    2014-01-01

    Motile growth cones lead growing axons through developing tissues to synaptic targets. These behaviors depend on the organization and dynamics of actin filaments that fill the growth cone leading margin (peripheral (P-) domain). Actin filament organization in growth cones is regulated by actin-binding proteins that control all aspects of filament assembly, turnover, interactions with other filaments and cytoplasmic components, and participation in producing mechanical forces. Actin filament polymerization drives protrusion of sensory filopodia and lamellipodia, and actin filament connections to the plasma membrane link the filament network to adhesive contacts of filopodia and lamellipodia with other surfaces. These contacts stabilize protrusions and transduce mechanical forces generated by actomyosin activity into traction that pulls an elongating axon along the path towards its target. Adhesive ligands and extrinsic guidance cues bind growth cone receptors and trigger signaling activities involving Rho GTPases, kinases, phosphatases, cyclic nucleotides and [Ca++] fluxes. These signals regulate actin binding proteins to locally modulate actin polymerization, interactions and force transduction to steer the growth cone leading margin towards the sources of attractive cues and away from repellent guidance cues. PMID:24164353

  1. DSCR1 is required for both axonal growth cone extension and steering.

    PubMed

    Wang, Wei; Rai, Asit; Hur, Eun-Mi; Smilansky, Zeev; Chang, Karen T; Min, Kyung-Tai

    2016-05-23

    Local information processing in the growth cone is essential for correct wiring of the nervous system. As an axon navigates through the developing nervous system, the growth cone responds to extrinsic guidance cues by coordinating axon outgrowth with growth cone steering. It has become increasingly clear that axon extension requires proper actin polymerization dynamics, whereas growth cone steering involves local protein synthesis. However, molecular components integrating these two processes have not been identified. Here, we show that Down syndrome critical region 1 protein (DSCR1) controls axon outgrowth by modulating growth cone actin dynamics through regulation of cofilin activity (phospho/dephospho-cofilin). Additionally, DSCR1 mediates brain-derived neurotrophic factor-induced local protein synthesis and growth cone turning. Our study identifies DSCR1 as a key protein that couples axon growth and pathfinding by dually regulating actin dynamics and local protein synthesis. PMID:27185837

  2. Second messenger networks for accurate growth cone guidance.

    PubMed

    Akiyama, Hiroki; Kamiguchi, Hiroyuki

    2015-04-01

    Growth cones are able to navigate over long distances to find their appropriate target by following guidance cues that are often presented to them in the form of an extracellular gradient. These external cues are converted into gradients of specific signaling molecules inside growth cones, while at the same time these internal signals are amplified. The amplified instruction is then used to generate asymmetric changes in the growth cone turning machinery so that one side of the growth cone migrates at a rate faster than the other side, and thus the growth cone turns toward or away from the external cue. This review examines how signal specification and amplification can be achieved inside the growth cone by multiple second messenger signaling pathways activated downstream of guidance cues. These include the calcium ion, cyclic nucleotide, and phosphatidylinositol signaling pathways. PMID:24285606

  3. Y-P30 promotes axonal growth by stabilizing growth cones.

    PubMed

    Neumann, Janine R; Dash-Wagh, Suvarna; Jüngling, Kay; Tsai, Teresa; Meschkat, Martin; Räk, Andrea; Schönfelder, Sabine; Riedel, Christian; Hamad, Mohammad I K; Wiese, Stefan; Pape, Hans-Christian; Gottmann, Kurt; Kreutz, Michael R; Wahle, Petra

    2015-07-01

    The 30-amino acid peptide Y-P30, generated from the N-terminus of the human dermcidin precursor protein, has been found to promote neuronal survival, cell migration and neurite outgrowth by enhancing the interaction of pleiotrophin and syndecan-3. We now show that Y-P30 activates Src kinase and extracellular signal-regulated kinase (ERK). Y-P30 promotes axonal growth of mouse embryonic stem cell-derived neurons, embryonic mouse spinal cord motoneurons, perinatal rat retinal neurons, and rat cortical neurons. Y-P30-mediated axon growth was dependent on heparan sulfate chains. Y-P30 decreased the proportion of collapsing/degenerating growth cones of cortical axons in an Src and ERK-dependent manner. Y-P30 increased for 90 min in axonal growth cones the level of Tyr418-phosphorylated Src kinase and the amount of F-actin, and transiently the level of Tyr-phosphorylated ERK. Levels of total Src kinase, actin, GAP-43, cortactin and the glutamate receptor subunit GluN2B were not altered. When exposed to semaphorin-3a, Y-P30 protected a significant fraction of growth cones of cortical neurons from collapse. These results suggest that Y-P30 promotes axonal growth via Src- and ERK-dependent mechanisms which stabilize growth cones and confer resistance to collapsing factors. PMID:24728870

  4. Cinder cone growth modeled after Northeast crater, Mount Etna, Sicily

    NASA Technical Reports Server (NTRS)

    Mcgetchin, T. R.; Settle, M.; Chouet, B. A.

    1974-01-01

    The structure, physical properties of ejecta, ballistics, and growth of Northeast crater, a young pyroclastic cone that originated in 1911 near the summit of Mount Etna, Sicily, were studied in order to form a model of volcano cinder cone growth. Four stages of growth were discerned: (1) a simple cone; (2) a cone with an outward-dipping talus slope; (3) destruction of rounded rim by the inward migration of the upper edge of the talus pile; and (4) extension of limits of talus pile beyond the ballistic limit of ejecta trajectories. The model is used to predict the features of lunar and Martian cones, assuming that they erupted under conditions qualitatively similar to Etna's Northeast crater.

  5. Increase in Growth Cone Size Correlates with Decrease in Neurite Growth Rate

    PubMed Central

    Ren, Yuan

    2016-01-01

    Several important discoveries in growth cone cell biology were made possible by the use of growth cones derived from cultured Aplysia bag cell neurons, including the characterization of the organization and dynamics of the cytoskeleton. The majority of these Aplysia studies focused on large growth cones induced by poly-L-lysine substrates at early stages in cell culture. Under these conditions, the growth cones are in a steady state with very little net advancement. Here, we offer a comprehensive cellular analysis of the motile behavior of Aplysia growth cones in culture beyond this pausing state. We found that average growth cone size decreased with cell culture time whereas average growth rate increased. This inverse correlation of growth rate and growth cone size was due to the occurrence of large growth cones with a peripheral domain larger than 100 μm2. The large pausing growth cones had central domains that were less consistently aligned with the direction of growth and could be converted into smaller, faster-growing growth cones by addition of a three-dimensional collagen gel. We conclude that the significant lateral expansion of lamellipodia and filopodia as observed during these culture conditions has a negative effect on neurite growth. PMID:27274874

  6. Functional Complexity of the Axonal Growth Cone: A Proteomic Analysis

    PubMed Central

    Estrada-Bernal, Adriana; Sanford, Staci D.; Sosa, Lucas J.; Simon, Glenn C.; Hansen, Kirk C.; Pfenninger, Karl H.

    2012-01-01

    The growth cone, the tip of the emerging neurite, plays a crucial role in establishing the wiring of the developing nervous system. We performed an extensive proteomic analysis of axonal growth cones isolated from the brains of fetal Sprague-Dawley rats. Approximately 2000 proteins were identified at ≥99% confidence level. Using informatics, including functional annotation cluster and KEGG pathway analysis, we found great diversity of proteins involved in axonal pathfinding, cytoskeletal remodeling, vesicular traffic and carbohydrate metabolism, as expected. We also found a large and complex array of proteins involved in translation, protein folding, posttranslational processing, and proteasome/ubiquitination-dependent degradation. Immunofluorescence studies performed on hippocampal neurons in culture confirmed the presence in the axonal growth cone of proteins representative of these processes. These analyses also provide evidence for rough endoplasmic reticulum and reveal a reticular structure equipped with Golgi-like functions in the axonal growth cone. Furthermore, Western blot revealed the growth cone enrichment, relative to fetal brain homogenate, of some of the proteins involved in protein synthesis, folding and catabolism. Our study provides a resource for further research and amplifies the relatively recently developed concept that the axonal growth cone is equipped with proteins capable of performing a highly diverse range of functions. PMID:22384089

  7. Sema3F downregulates p53 expression leading to axonal growth cone collapse in primary hippocampal neurons

    PubMed Central

    Yang, Guanglu; Qu, Xiang; Zhang, Junmei; Zhao, Weidong; Wang, Hua

    2012-01-01

    Hippocampal nerve growth is regulated by the coordinated action of numerous external stimuli, including positively acting neurotrophin-derived growth cues and restrictive semaphorin cues, however the underlying cellular mechanisms remain largely unclear. We examined the potential cellular mechanism of Semaphorin3F (Sema3F) in cultured primary hippocampal neurons. We show that Sema3F can down-regulate p53 expression in primary hippocampal neurons, thereby contributing to growth cone collapse. Sema3F suppressed p53-induced pathways, which we show to be required to maintain growth cone structure. Sema3F-induced growth cone collapse was partially reversed by overexpression of p53, which promoted growth cone extension. Inhibition of p53 function by inhibitor, siRNAs, induced axonal growth cone collapse, whereas p53 over-expression led to larger growth cones in cultured primary hippocampal neurons.These data reveal a novel mechanism by which Sema3F can induce hippocampal neuron growth cone collapse and provide evidence for an intracellular mechanism for cross talk between positive and negative axon growth cues. PMID:22977659

  8. Kinetic-structural analysis of neuronal growth cone veil motility.

    PubMed

    Mongiu, Anne K; Weitzke, Elizabeth L; Chaga, Oleg Y; Borisy, Gary G

    2007-03-15

    Neuronal growth cone advance was investigated by correlative light and electron microscopy carried out on chick dorsal root ganglion cells. Advance was analyzed in terms of the two principal organelles responsible for protrusive motility in the growth cone - namely, veils and filopodia. Veils alternated between rapid phases of protrusion and retraction. Electron microscopy revealed characteristic structural differences between the phases. Our results provide a significant advance in three respects: first, protruding veils are comprised of a densely branched network of actin filaments that is lamellipodial in appearance and includes the Arp2/3 complex. On the basis of this structural and biomarker evidence, we infer that the dendritic nucleation and/or array-treadmilling mechanism of protrusive motility is conserved in veil protrusion of growth cones as in the motility of fibroblasts; second, retracting veils lack dendritic organization but contain a sparse network of long filaments; and third, growth cone filopodia have the capacity to nucleate dendritic networks along their length, a property consistent with veil formation seen at the light microscopic level but not previously understood in supramolecular terms. These elements of veil and filopodial organization, when taken together, provide a conceptual framework for understanding the structural basis of growth cone advance. PMID:17327278

  9. Ultra-short pulses to signal neuronal growth cone machinery

    NASA Astrophysics Data System (ADS)

    Mathew, Manoj; Amat-Roldan, Ivan; Andres, Rosa; Cormack, Iain G.; Artigas, David; Soriano, Eduardo; Loza-Alvarez, Pablo

    2007-02-01

    Measurable change in the sensory motor machinery of growth cones are induced by non contact femtosecond laser. The focused laser beam with an average power of 3 mW was positioned at some distance away from the closest fillopodia of cortical neurons from primary cell cultures (mice E15). By identifying a set of preliminary parameters we were able to statistically analyze the phenomenological behavior of the fillopodia and classify the effects different conditions of laser light has on the growth cone. Results show that fillopodia become significantly biased towards the focused femtosecond laser light. The same experiment performed with continuous wave (CW) produced results which were indistinguishable from the case where there is no laser light present (placebo condition) indicating no clear effects of the CW laser light on the fillopodia at a distance. These findings show the potential for ultrashort pulsed light to become a new type of pathfinding cue for neuronal growth cones.

  10. Birth order dependent growth cone segregation determines synaptic layer identity in the Drosophila visual system

    PubMed Central

    Kulkarni, Abhishek; Ertekin, Deniz; Lee, Chi-Hon; Hummel, Thomas

    2016-01-01

    The precise recognition of appropriate synaptic partner neurons is a critical step during neural circuit assembly. However, little is known about the developmental context in which recognition specificity is important to establish synaptic contacts. We show that in the Drosophila visual system, sequential segregation of photoreceptor afferents, reflecting their birth order, lead to differential positioning of their growth cones in the early target region. By combining loss- and gain-of-function analyses we demonstrate that relative differences in the expression of the transcription factor Sequoia regulate R cell growth cone segregation. This initial growth cone positioning is consolidated via cell-adhesion molecule Capricious in R8 axons. Further, we show that the initial growth cone positioning determines synaptic layer selection through proximity-based axon-target interactions. Taken together, we demonstrate that birth order dependent pre-patterning of afferent growth cones is an essential pre-requisite for the identification of synaptic partner neurons during visual map formation in Drosophila. DOI: http://dx.doi.org/10.7554/eLife.13715.001 PMID:26987017

  11. Birth order dependent growth cone segregation determines synaptic layer identity in the Drosophila visual system.

    PubMed

    Kulkarni, Abhishek; Ertekin, Deniz; Lee, Chi-Hon; Hummel, Thomas

    2016-01-01

    The precise recognition of appropriate synaptic partner neurons is a critical step during neural circuit assembly. However, little is known about the developmental context in which recognition specificity is important to establish synaptic contacts. We show that in the Drosophila visual system, sequential segregation of photoreceptor afferents, reflecting their birth order, lead to differential positioning of their growth cones in the early target region. By combining loss- and gain-of-function analyses we demonstrate that relative differences in the expression of the transcription factor Sequoia regulate R cell growth cone segregation. This initial growth cone positioning is consolidated via cell-adhesion molecule Capricious in R8 axons. Further, we show that the initial growth cone positioning determines synaptic layer selection through proximity-based axon-target interactions. Taken together, we demonstrate that birth order dependent pre-patterning of afferent growth cones is an essential pre-requisite for the identification of synaptic partner neurons during visual map formation in Drosophila. PMID:26987017

  12. Variability and Reliabiltiy in Axon Growth Cone Navigation Decision Making

    NASA Astrophysics Data System (ADS)

    Garnelo, Marta; Ricoult, Sébastien G.; Juncker, David; Kennedy, Timothy E.; Faisal, Aldo A.

    2015-03-01

    The nervous system's wiring is a result of axon growth cones navigating through specific molecular environments during development. In order to reach their target, growth cones need to make decisions under uncertainty as they are faced with stochastic sensory information and probabilistic movements. The overall system therefore exhibits features of whole organisms (perception, decision making, action) in the subset of a single cell. We aim to characterise growth cone navigation in defined nano-dot guidance cue environments, by using the tools of computational neuroscience to conduct ``molecular psychophysics.'' We start with a generative model of growth cone behaviour and we 1. characterise sensory and internal sources of noise contributing to behavioural variables, by combining knowledge of the underlying stochastic dynamics in cue sensing and the growth of the cytoskeleton. This enables us to 2. produce bottom-up lower limit estimates of behavioural response reliability and visualise it as probability distributions over axon growth trajectories. Given this information we can match our in silico model's ``psychometric'' decision curves with empirical data. Finally we use a Monte-Carlo approach to predict response distributions of axon trajectories from our model.

  13. Growth Cone Biomechanics in Peripheral and Central Nervous System Neurons

    NASA Astrophysics Data System (ADS)

    Urbach, Jeffrey; Koch, Daniel; Rosoff, Will; Geller, Herbert

    2012-02-01

    The growth cone, a highly motile structure at the tip of an axon, integrates information about the local environment and modulates outgrowth and guidance, but little is known about effects of external mechanical cues and internal mechanical forces on growth-cone mediated guidance. We have investigated neurite outgrowth, traction forces and cytoskeletal substrate coupling on soft elastic substrates for dorsal root ganglion (DRG) neurons (from the peripheral nervous system) and hippocampal neurons (from the central) to see how the mechanics of the microenvironment affect different populations. We find that the biomechanics of DRG neurons are dramatically different from hippocampal, with DRG neurons displaying relatively large, steady traction forces and maximal outgrowth and forces on substrates of intermediate stiffness, while hippocampal neurons display weak, intermittent forces and limited dependence of outgrowth and forces on substrate stiffness. DRG growth cones have slower rates of retrograde actin flow and higher density of localized paxillin (a protein associated with substrate adhesion complexes) compared to hippocampal neurons, suggesting that the difference in force generation is due to stronger adhesions and therefore stronger substrate coupling in DRG growth cones.

  14. Suppression of Radixin and Moesin Alters Growth Cone Morphology, Motility, and Process Formation In Primary Cultured Neurons

    PubMed Central

    Paglini, Gabriela; Kunda, Patricia; Quiroga, Santiago; Kosik, Kenneth; Cáceres, Alfredo

    1998-01-01

    In this study we have examined the cellular functions of ERM proteins in developing neurons. The results obtained indicate that there is a high degree of spatial and temporal correlation between the expression and subcellular localization of radixin and moesin with the morphological development of neuritic growth cones. More importantly, we show that double suppression of radixin and moesin, but not of ezrin–radixin or ezrin–moesin, results in reduction of growth cone size, disappearance of radial striations, retraction of the growth cone lamellipodial veil, and disorganization of actin filaments that invade the central region of growth cones where they colocalize with microtubules. Neuritic tips from radixin–moesin suppressed neurons displayed high filopodial protrusive activity; however, its rate of advance is 8–10 times slower than the one of growth cones from control neurons. Radixin–moesin suppressed neurons have short neurites and failed to develop an axon-like neurite, a phenomenon that appears to be directly linked with the alterations in growth cone structure and motility. Taken collectively, our data suggest that by regulating key aspects of growth cone development and maintenance, radixin and moesin modulate neurite formation and the development of neuronal polarity. PMID:9786954

  15. Netrin-1 induces local translation of down syndrome cell adhesion molecule in axonal growth cones.

    PubMed

    Jain, Shruti; Welshhans, Kristy

    2016-07-01

    Down syndrome cell adhesion molecule (DSCAM) plays an important role in many neurodevelopmental processes such as axon guidance, dendrite arborization, and synapse formation. DSCAM is located in the Down syndrome trisomic region of human chromosome 21 and may contribute to the Down syndrome brain phenotype, which includes a reduction in the formation of long-distance connectivity. The local translation of a select group of mRNA transcripts within growth cones is necessary for the formation of appropriate neuronal connectivity. Interestingly, we have found that Dscam mRNA is localized to growth cones of mouse hippocampal neurons, and is dynamically regulated in response to the axon guidance molecule, netrin-1. Furthermore, netrin-1 stimulation results in an increase in locally translated DSCAM protein in growth cones. Deleted in colorectal cancer (DCC), a netrin-1 receptor, is required for the netrin-1-induced increase in Dscam mRNA local translation. We also find that two RNA-binding proteins-fragile X mental retardation protein (FMRP) and cytoplasmic polyadenylation element binding protein (CPEB)-colocalize with Dscam mRNA in growth cones, suggesting their regulation of Dscam mRNA localization and translation. Finally, overexpression of DSCAM in mouse cortical neurons results in a severe stunting of axon outgrowth and branching, suggesting that an increase in DSCAM protein results in a structural change having functional consequences. Taken together, these results suggest that netrin-1-induced local translation of Dscam mRNA during embryonic development may be an important mechanism to regulate axon growth and guidance in the developing nervous system. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 799-816, 2016. PMID:26518186

  16. The role of cytoskeleton in organizing growth cones: a microfilament- associated growth cone component depends upon microtubules for its localization

    PubMed Central

    1989-01-01

    We are interested in the relationship between the cytoskeleton and the organization of polarized cell morphology. We show here that the growth cones of hippocampal neurons in culture are specifically stained by a monoclonal antibody called 13H9. In other systems, the antigen recognized by 13H9 is associated with marginal bands of chicken erythrocytes and shows properties of both microtubule-and microfilament- associated proteins (Birgbauer, E., and F. Solomon. 1989 J. Cell Biol. 109:1609-1620). This dual nature is manifest in hippocampal neurons as well. At early stages after plating, the antibody stains the circumferential lamellipodia that mediate initial cell spreading. As processes emerge, 13H9 staining is heavily concentrated in the distal regions of growth cones, particularly in lamellipodial fans. In these cells, the 13H9 staining is complementary to the localization of assembled microtubules. It colocalizes partially, but not entirely, with phalloidin staining of assembled actin. Incubation with nocodazole rapidly induces microtubule depolymerization, which proceeds in the distal-to-proximal direction in the processes. At the same time, a rapid and dramatic redistribution of the 13H9 staining occurs; it delocalizes along the axon shaft, becoming clearly distinct from the phalloidin staining and always remaining distal to the receding front of assembled microtubules. After longer times without assembled microtubules, no staining of 13H9 can be detected. Removal of the nocodazole allows the microtubules to reform, in an ordered proximal-to- distal fashion. The 13H9 immunoreactivity also reappears, but only in the growth cones, not in any intermediate positions along the axon, and only after the reformation of microtubules is complete. The results indicate that the antigen recognized by 13H9 is highly concentrated in growth cones, closely associated with polymerized actin, and that its proper localization depends upon intact microtubules. PMID:2677024

  17. Roles of channels and receptors in the growth cone during PNS axonal regeneration.

    PubMed

    Shim, Sangwoo; Ming, Guo-li

    2010-05-01

    Neurons in the peripheral nervous system (PNS) are known to maintain a regenerative capacity and will normally regenerate their axons within a permissive growth environment. The success of regeneration in the PNS largely depends on maintenance of the supportive basal lamina membrane, efficient removal of axonal and myelin debris by macrophages and Schwann cells, expression of neurotrophic factors by Schwann cells, and up-regulation of the intrinsic growth program in PNS neurons. The PNS regenerative process is well characterized through initial Wallerian degeneration followed by axonal sprouting, formation of neuronal growth cones, active axonal growth to the target, and finally sensory and motor functional recovery. The initiation and maintenance of active growth cones during peripheral nerve regeneration recapitulate many aspects of early neural development and are achieved through the activation of complex signaling cascades, involving various receptors, channels, cytoplasmic signaling cascades, as well as transcriptional and translational programs. This review focuses on roles of cell surface ion channels and receptors in the growth cone during Wallerian degeneration and axon regeneration in the PNS. PMID:19833126

  18. Inhibiting geranylgeranylation increases neurite branching and differentially activates cofilin in cell bodies and growth cones.

    PubMed

    Samuel, Filsy; Reddy, Jairus; Kaimal, Radhika; Segovia, Vianey; Mo, Huanbiao; Hynds, DiAnna L

    2014-08-01

    Inhibitors of the mevalonate pathway, including the highly prescribed statins, reduce the production of cholesterol and isoprenoids such as geranylgeranyl pyrophosphates. The Rho family of small guanine triphosphatases (GTPases) requires isoprenylation, specifically geranylgeranylation, for activation. Because Rho GTPases are primary regulators of actin filament rearrangements required for process extension, neurite arborization, and synaptic plasticity, statins may affect cognition or recovery from nervous system injury. Here, we assessed how manipulating geranylgeranylation affects neurite initiation, elongation, and branching in neuroblastoma growth cones. Treatment with the statin, lovastatin (20 μM), decreased measures of neurite initiation by 17.0 to 19.0 % when a source of cholesterol was present and increased neurite branching by 4.03- to 9.54-fold (regardless of exogenous cholesterol). Neurite elongation was increased by treatment with lovastatin only in cholesterol-free culture conditions. Treatment with lovastatin decreased growth cone actin filament content by up to 24.3 %. In all cases, co-treatment with the prenylation precursor, geranylgeraniol (10 μM), reversed the effect of lovastatin. In a prior work, statin effects on outgrowth were linked to modulating the actin depolymerizing factor, cofilin. In our assays, treatment with lovastatin or geranylgeraniol decreased cofilin phosphorylation in whole cell lysates. However, lovastatin increased cofilin phosphorylation in cell bodies and decreased it in growth cones, indicating differential regulation in specific cell regions. Together, we interpret these data to suggest that protein geranylgeranylation likely regulates growth cone actin filament content and subsequent neurite outgrowth through mechanisms that also affect actin nucleation and polymerization. PMID:24515839

  19. Bidirectional interactions between NOX2-type NADPH oxidase and the F-actin cytoskeleton in neuronal growth cones.

    PubMed

    Munnamalai, Vidhya; Weaver, Cory J; Weisheit, Corinne E; Venkatraman, Prahatha; Agim, Zeynep Sena; Quinn, Mark T; Suter, Daniel M

    2014-08-01

    NADPH oxidases are important for neuronal function but detailed subcellular localization studies have not been performed. Here, we provide the first evidence for the presence of functional NADPH oxidase 2 (NOX2)-type complex in neuronal growth cones and its bidirectional relationship with the actin cytoskeleton. NADPH oxidase inhibition resulted in reduced F-actin content, retrograde F-actin flow, and neurite outgrowth. Stimulation of NADPH oxidase via protein kinase C activation increased levels of hydrogen peroxide in the growth cone periphery. The main enzymatic NADPH oxidase subunit NOX2/gp91(phox) localized to the growth cone plasma membrane and showed little overlap with the regulatory subunit p40(phox) . p40(phox) itself exhibited colocalization with filopodial actin bundles. Differential subcellular fractionation revealed preferential association of NOX2/gp91(phox) and p40(phox) with the membrane and the cytoskeletal fraction, respectively. When neurite growth was evoked with beads coated with the cell adhesion molecule apCAM, we observed a significant increase in colocalization of p40(phox) with NOX2/gp91(phox) at apCAM adhesion sites. Together, these findings suggest a bidirectional functional relationship between NADPH oxidase activity and the actin cytoskeleton in neuronal growth cones, which contributes to the control of neurite outgrowth. We have previously shown that reactive oxygen species (ROS) are critical for actin organization and dynamics in neuronal growth cones as well as neurite outgrowth. Here, we report that the cytosolic subunit p40(phox) of the NOX2-type NADPH oxidase complex is partially associated with F-actin in neuronal growth cones, while ROS produced by this complex regulates F-actin dynamics and neurite growth. These findings provide evidence for a bidirectional relationship between NADPH oxidase activity and the actin cytoskeleton in neuronal growth cones. PMID:24702317

  20. Use of scanning ion conductance microscopy to guide and redirect neuronal growth cones.

    PubMed

    Pellegrino, Mario; Orsini, Paolo; De Gregorio, Francesca

    2009-07-01

    Scanning ion conductance microscopy has been applied to neuronal growth cones of the leech either to image or to stimulate them. Growth cone advance was recorded in non-contact mode using a 2% ion current decrease criterion for pipette-membrane distance control. We demonstrate effective growth cone remodelling using a 5% criterion (near-scanning). Recurrent line near-scanning aligned growth cone processes along the scan line. The new membrane protrusions, marked by DiI, started a few minutes after scanning onset and progressively grew in thickness. Using scanning patterns suitable for connecting distinct growth cones, new links were consistently developed. Although the underlying mechanism is still a matter for investigation, a mechanical perturbation produced by the moving probe appeared to induce the process formation. Thanks to its deterministic and interactive features, this novel approach to guiding growth cones is a promising way to develop networks of identified neurons as well as link them with artificial structures. PMID:19447298

  1. Cyclic GMP evoked calcium transients in olfactory receptor cell growth cones.

    PubMed

    Kafitz, K W; Leinders-Zufall, T; Zufall, F; Greer, C A

    2000-03-20

    Nitric oxide-induced calcium transients in growth cones are believed to be mediated by cyclic nucleotides. Because nitric oxide is thought to influence the development of olfactory receptor cells (ORCs), we have begun to explore the effect of cyclic nucleotides on ORC growth cones. Cultured ORCs were loaded with fluo-3 AM and confocal imaging was employed to monitor calcium transients following cyclic nucleotide-gated channel activation. Application of 8-bromo-cGMP at the growth cone caused transient increases in fluorescence which were restricted to the growth cone and lasted tens of seconds. The signal was abolished by LY83583, an inhibitor of cyclic nucleotide-gated channels. 8-Bromo-cGMP also inhibited further extension of growth cones. The data indicate that ORC growth cones exhibit cGMP-dependent calcium transients that are consistent with those generated by cyclic nucleotide-gated channels. PMID:10757499

  2. Radixin Is Involved in Lamellipodial Stability during Nerve Growth Cone Motility

    PubMed Central

    Castelo, Leslie; Jay, Daniel G.

    1999-01-01

    Immunocytochemistry and in vitro studies have suggested that the ERM (ezrin-radixin-moesin) protein, radixin, may have a role in nerve growth cone motility. We tested the in situ role of radixin in chick dorsal root ganglion growth cones by observing the effects of its localized and acute inactivation. Microscale chromophore-assisted laser inactivation (micro-CALI) of radixin in growth cones causes a 30% reduction of lamellipodial area within the irradiated region whereas all control treatments did not affect lamellipodia. Micro-CALI of radixin targeted to the middle of the leading edge often split growth cones to form two smaller growth cones during continued forward movement (>80%). These findings suggest a critical role for radixin in growth cone lamellipodia that is similar to ezrin function in pseudopodia of transformed fibroblasts. They are consistent with radixin linking actin filaments to each other or to the membrane during motility. PMID:10233159

  3. Plant Growth Regulators.

    ERIC Educational Resources Information Center

    Nickell, Louis G.

    1978-01-01

    Describes the effect of "plant growth regulators" on plants, such as controlling the flowering, fruit development, plant size, and increasing crop yields. Provides a list of plant growth regulators which includes their chemical, common, and trade names, as well as their different use(s). (GA)

  4. Using plusTipTracker software to measure microtubule dynamics in Xenopus laevis growth cones

    PubMed Central

    Stout, Alina; D’Amico, Salvatore; Enzenbacher, Tiffany; Ebbert, Patrick; Lowery, Laura Anne

    2014-01-01

    Microtubule (MT) plus-end-tracking proteins (+TIPs) localize to the growing plus-ends of MTs and regulate MT dynamics1,2. One of the most well-known and widely-utilized +TIPs for analyzing MT dynamics is the End-Binding protein, EB1, which binds all growing MT plus-ends, and thus, is a marker for MT polymerization1. Many studies of EB1 behavior within growth cones have used time-consuming and biased computer-assisted, hand-tracking methods to analyze individual MTs1-3. Our approach is to quantify global parameters of MT dynamics using the software package, plusTipTracker4, following the acquisition of high-resolution, live images of tagged EB1 in cultured embryonic growth cones5. This software is a Matlab-based, open-source, user-friendly package that combines automated detection, tracking, visualization, and analysis for movies of fluorescently-labeled +TIPs. Here, we present the protocol for using plusTipTracker for the analysis of fluorescently-labeled +TIP comets in cultured Xenopus laevis growth cones. However, this software can also be used to characterize MT dynamics in various cell types6-8. PMID:25225829

  5. Using plusTipTracker software to measure microtubule dynamics in Xenopus laevis growth cones.

    PubMed

    Stout, Alina; D'Amico, Salvatore; Enzenbacher, Tiffany; Ebbert, Patrick; Lowery, Laura Anne

    2014-01-01

    Microtubule (MT) plus-end-tracking proteins (+TIPs) localize to the growing plus-ends of MTs and regulate MT dynamics(1,2). One of the most well-known and widely-utilized +TIPs for analyzing MT dynamics is the End-Binding protein, EB1, which binds all growing MT plus-ends, and thus, is a marker for MT polymerization(1). Many studies of EB1 behavior within growth cones have used time-consuming and biased computer-assisted, hand-tracking methods to analyze individual MTs(1-3). Our approach is to quantify global parameters of MT dynamics using the software package, plusTipTracker(4), following the acquisition of high-resolution, live images of tagged EB1 in cultured embryonic growth cones(5). This software is a MATLAB-based, open-source, user-friendly package that combines automated detection, tracking, visualization, and analysis for movies of fluorescently-labeled +TIPs. Here, we present the protocol for using plusTipTracker for the analysis of fluorescently-labeled +TIP comets in cultured Xenopus laevis growth cones. However, this software can also be used to characterize MT dynamics in various cell types(6-8). PMID:25225829

  6. FLIM FRET Visualization of Cdc42 Activation by Netrin-1 in Embryonic Spinal Commissural Neuron Growth Cones

    PubMed Central

    Rappaz, Benjamin; Lai Wing Sun, Karen; Correia, James P.; Wiseman, Paul W.; Kennedy, Timothy E.

    2016-01-01

    Netrin-1 is an essential extracellular chemoattractant that signals through its receptor DCC to guide commissural axon extension in the embryonic spinal cord. DCC directs the organization of F-actin in growth cones by activating an intracellular protein complex that includes the Rho GTPase Cdc42, a critical regulator of cell polarity and directional migration. To address the spatial distribution of signaling events downstream of netrin-1, we expressed the FRET biosensor Raichu-Cdc42 in cultured embryonic rat spinal commissural neurons. Using FLIM-FRET imaging we detected rapid activation of Cdc42 in neuronal growth cones following application of netrin-1. Investigating the signaling mechanisms that control Cdc42 activation by netrin-1, we demonstrate that netrin-1 rapidly enriches DCC at the leading edge of commissural neuron growth cones and that netrin-1 induced activation of Cdc42 in the growth cone is blocked by inhibiting src family kinase signaling. These findings reveal the activation of Cdc42 in embryonic spinal commissural axon growth cones and support the conclusion that src family kinase activation downstream of DCC is required for Cdc42 activation by netrin-1. PMID:27482713

  7. Filopodial dynamics and growth cone stabilization in Drosophila visual circuit development

    PubMed Central

    Özel, Mehmet Neset; Langen, Marion; Hassan, Bassem A; Hiesinger, P Robin

    2015-01-01

    Filopodial dynamics are thought to control growth cone guidance, but the types and roles of growth cone dynamics underlying neural circuit assembly in a living brain are largely unknown. To address this issue, we have developed long-term, continuous, fast and high-resolution imaging of growth cone dynamics from axon growth to synapse formation in cultured Drosophila brains. Using R7 photoreceptor neurons as a model we show that >90% of the growth cone filopodia exhibit fast, stochastic dynamics that persist despite ongoing stepwise layer formation. Correspondingly, R7 growth cones stabilize early and change their final position by passive dislocation. N-Cadherin controls both fast filopodial dynamics and growth cone stabilization. Surprisingly, loss of N-Cadherin causes no primary targeting defects, but destabilizes R7 growth cones to jump between correct and incorrect layers. Hence, growth cone dynamics can influence wiring specificity without a direct role in target recognition and implement simple rules during circuit assembly. DOI: http://dx.doi.org/10.7554/eLife.10721.001 PMID:26512889

  8. Growth regulation of cancer

    SciTech Connect

    Lippman, M.E. )

    1988-01-01

    This book contains proceedings of an Ortho-UCLA Symposium on growth regulation of cancer. Included are the following chapters: Swiss 3T3 mouse embryo fibroblasts transfected with a human Prepro-GRP gene synthesize and secrete Pro-GRP rather than GRP, proto-oncogenes as mediators of growth and development: discussion summary, animal studies and clinical trials.

  9. Genes that guide growth cones along the C. elegans ventral nerve cord.

    PubMed

    Wightman, B; Baran, R; Garriga, G

    1997-07-01

    During nervous system development, growth cone pioneering and fasciculation contribute to nerve bundle structure. Pioneer growth cones initially navigate along neuroglia to establish an axon scaffold that guides later extending growth cones. In C. elegans, the growth cone of the PVPR neuron pioneers the left ventral nerve cord bundle, providing a path for the embryonic extensions of the PVQL and AVKR growth cones. Later during larval development, the HSNL growth cone follows cues in the left ventral nerve cord bundle provided by the PVPR and PVQL axons. Here we show that mutations in the genes enu-1, fax-1, unc-3, unc-30, unc-42 and unc-115 disrupt pathfinding of growth cones along the left ventral nerve cord bundle. Our results indicate that unc-3 and unc-30 function in ventral nerve cord pioneering and that enu-1, fax-1, unc-42 and unc-115 function in recognition of the PVPR and PVQL axons by the AVKR and HSNL growth cones. PMID:9216999

  10. Regulation of Mammalian Cone Phototransduction by Recoverin and Rhodopsin Kinase*

    PubMed Central

    Sakurai, Keisuke; Chen, Jeannie; Khani, Shahrokh C.; Kefalov, Vladimir J.

    2015-01-01

    Cone photoreceptors function under daylight conditions and are essential for color perception and vision with high temporal and spatial resolution. A remarkable feature of cones is that, unlike rods, they remain responsive in bright light. In rods, light triggers a decline in intracellular calcium, which exerts a well studied negative feedback on phototransduction that includes calcium-dependent inhibition of rhodopsin kinase (GRK1) by recoverin. Rods and cones share the same isoforms of recoverin and GRK1, and photoactivation also triggers a calcium decline in cones. However, the molecular mechanisms by which calcium exerts negative feedback on cone phototransduction through recoverin and GRK1 are not well understood. Here, we examined this question using mice expressing various levels of GRK1 or lacking recoverin. We show that although GRK1 is required for the timely inactivation of mouse cone photoresponse, gradually increasing its expression progressively delays the cone response recovery. This surprising result is in contrast with the known effect of increasing GRK1 expression in rods. Notably, the kinetics of cone responses converge and become independent of GRK1 levels for flashes activating more than ∼1% of cone pigment. Thus, mouse cone response recovery in bright light is independent of pigment phosphorylation and likely reflects the spontaneous decay of photoactivated visual pigment. We also find that recoverin potentiates the sensitivity of cones in dim light conditions but does not contribute to their capacity to function in bright light. PMID:25673692

  11. The B3 Subunit of the Cone Cyclic Nucleotide-gated Channel Regulates the Light Responses of Cones and Contributes to the Channel Structural Flexibility.

    PubMed

    Ding, Xi-Qin; Thapa, Arjun; Ma, Hongwei; Xu, Jianhua; Elliott, Michael H; Rodgers, Karla K; Smith, Marci L; Wang, Jin-Shan; Pittler, Steven J; Kefalov, Vladimir J

    2016-04-15

    Cone photoreceptor cyclic nucleotide-gated (CNG) channels play a pivotal role in cone phototransduction, which is a process essential for daylight vision, color vision, and visual acuity. Mutations in the cone channel subunits CNGA3 and CNGB3 are associated with human cone diseases, including achromatopsia, cone dystrophies, and early onset macular degeneration. Mutations in CNGB3 alone account for 50% of reported cases of achromatopsia. This work investigated the role of CNGB3 in cone light response and cone channel structural stability. As cones comprise only 2-3% of the total photoreceptor population in the wild-type mouse retina, we used Cngb3(-/-)/Nrl(-/-) mice with CNGB3 deficiency on a cone-dominant background in our study. We found that, in the absence of CNGB3, CNGA3 was able to travel to the outer segments, co-localize with cone opsin, and form tetrameric complexes. Electroretinogram analyses revealed reduced cone light response amplitude/sensitivity and slower response recovery in Cngb3(-/-)/Nrl(-/-) mice compared with Nrl(-/-) mice. Absence of CNGB3 expression altered the adaptation capacity of cones and severely compromised function in bright light. Biochemical analysis demonstrated that CNGA3 channels lacking CNGB3 were more resilient to proteolysis than CNGA3/CNGB3 channels, suggesting a hindered structural flexibility. Thus, CNGB3 regulates cone light response kinetics and the channel structural flexibility. This work advances our understanding of the biochemical and functional role of CNGB3 in cone photoreceptors. PMID:26893377

  12. Live cell imaging of neuronal growth cone motility and guidance in vitro

    PubMed Central

    Suter, Daniel M.

    2013-01-01

    Summary The neuronal growth cone, a highly motile structure at the tip of neuronal processes, is an excellent model system for studying directional cell movements. While biochemical and genetic approaches unveiled molecular interactions between ligand, receptor, signaling and cytoskeleton-associated proteins controlling axonal growth and guidance, in vitro live cell imaging has emerged as a crucial approach for dissecting cellular mechanisms of growth cone motility and guidance. Important insights into these mechanisms have been gained from studies using the large growth cones elaborated by Aplysia californica neurons, an outstanding model system for live cell imaging for a number of reasons. Identified neurons can be isolated and imaged at room temperature. Aplysia growth cones are 5–10 times larger than growth cones from other species, making them suitable for quantitative high-resolution imaging of cytoskeletal protein dynamics and biophysical approaches. Lastly, protein, RNA, fluorescent probes and small molecules can be microinjected into the neuronal cell body for localization and functional studies. The following chapter describes culturing of Aplysia bag cell neurons, live cell imaging of neuronal growth cones using differential interference contrast and fluorescent speckle microscopy as well as the restrained bead interaction assay to induce adhesion-mediated growth cone guidance in vitro. PMID:21748670

  13. Protein synthesis in distal axons is not required for growth cone responses to guidance cues

    PubMed Central

    Roche, Florence K.; Marsick, Bonnie M.; Letourneau, Paul C.

    2009-01-01

    Recent evidence suggests growth cone responses to guidance cues require local protein synthesis. Using chick neurons, we investigated whether protein synthesis is required for growth cones of several types to respond to guidance cues. First, we found that global inhibition of protein synthesis stops axonal elongation after two hr. When protein synthesis inhibitors were added 15 min before adding guidance cues, we found no changes in the typical responses of retinal, sensory and sympathetic growth cones. In the presence of cycloheximide or anisomycin, ephrin-A2, slit-3, and semaphorin3A still induced growth cone collapse and loss of actin filaments, NGF and NT-3 still induced growth cone protrusion and increased F-actin, and sensory growth cones turned toward an NGF source. In compartmented chambers that separated perikarya from axons, axons grew for 24-48 hr in the presence of cycloheximide and responded to negative and positive cues. Our results indicate that protein synthesis is not strictly required in the mechanisms for growth cone responses to many guidance cues. Differences between our results and other studies may exist because of different cellular metabolic levels in in vitro conditions, and a difference in when axonal functions become dependent on local protein synthesis. PMID:19158291

  14. Diethylstilbestrol alters the morphology and calcium levels of growth cones of PC12 cells in vitro.

    PubMed

    Janevski, J; Choh, V; Stopper, H; Schiffmann, D; De Boni, U

    1993-01-01

    Diethylstilbestrol (DES) is a synthetic estrogen with carcinogenic properties. DES is known to alter cytoskeletal components, including the organization of actin stress fibres in C6 rat glioma cells. In a test of the hypothesis that DES disrupts actin filaments of growth cones in neuron-like cells, DES-induced changes in filopodial lengths were quantified in rat pheochromocytoma (PC12) cells in vitro. DES significantly altered growth cone morphology, with collapse of growth cone filopodia and neurite retraction invariably occurring at a concentration of 10 microM. At 5 microM DES, transient reductions in total filopodial lengths occurred. At DES concentrations of 0.1 nM and 1 nM, reductions in total filopodial lengths occurred in a fraction of growth cones. Evidence exists which shows that growth cone activity and morphology are intimately linked to levels of intracellular, free calcium and that DES increases such levels. Measurements of free intracellular calcium levels by fluorescence microscopy, at times concurrent with the DES-induced reduction in total filopodial lengths, showed that calcium levels were indeed significantly increased by 10 microM DES. Labelling of filamentous actin (f-actin) with FITC-phalloidin showed that the f-actin distribution in growth cones exposed to DES could not be differentiated from the distribution found in spontaneously retracting growth cones. Together with evidence which showed that growth cone motility was not affected, the results are taken to indicate that DES, rather than acting directly on the cytoskeleton, exerts its effects indirectly, by a calcium-induced destabilization of actin filaments in the growth cone. PMID:8164893

  15. Concentration of membrane antigens by forward transport and trapping in neuronal growth cones.

    PubMed

    Sheetz, M P; Baumrind, N L; Wayne, D B; Pearlman, A L

    1990-04-20

    Formation of the nervous system requires that neuronal growth cones follow specific paths and then stop at recognition signals, sensed at the growth cone's leading edge. We used antibody-coated gold particles viewed by video-enhanced differential interference contrast microscopy to observe the distribution and movement of two cell surface molecules, N-CAM and the 2A1 antigen, on growth cones of cultured cortical neurons. Gold particles are occasionally transported forward at 1-2 microns/s to the leading edge where they are trapped but continue to move. Concentration at the edge persists after cytochalasin D treatment or ATP depletion, but active movements to and along edges cease. We also observed a novel outward movement of small cytoplasmic aggregates at 1.8 microns/s in filopodia. We suggest that active forward transport and trapping involve reversible attachment of antigens to and transport along cytoskeletal elements localized to edges of growth cones. PMID:2331749

  16. Growth cone travel in space and time: the cellular ensemble of cytoskeleton, adhesion, and membrane

    PubMed Central

    Vitriol, Eric A; Zheng, James Q

    2012-01-01

    Growth cones, found at the tip of axonal projections, are the sensory and motile organelles of developing neurons that enable axon pathfinding and target recognition for precise wiring of neural circuitry. To date, many families of conserved guidance molecules and their corresponding receptors have been identified that work in space and time to ensure billions of axons to their targets. Research in the past two decades has also gained significant insight into the mechanisms by which growth cones translate extracellular signals into directional migration. This review aims to examine new progress towards understanding the cellular mechanisms underlying directional motility of the growth cone and to discuss questions that remain to be addressed. Specifically we will focus on the cellular ensemble of cytoskeleton, adhesion, and membrane and examine how the intricate interplay between these processes orchestrates the directed movement of growth cones. PMID:22445336

  17. Crosstalk between Second Messengers Predicts the Motility of the Growth Cone

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takahiko; Nagase, Fumiaki; Hotta, Kohji; Oka, Kotaro

    2013-11-01

    Axon guidance involves multiple second messenger signal transduction pathways. Although each signal transduction pathway has been characterized, only a few studies have examined crosstalk between these cascades. Here, we applied a simultaneous second messenger imaging method to the growth cone and demonstrated correlations between cAMP, cGMP, and Ca2+. The levels of cAMP and cGMP in non-stimulated freely extending growth cones showed a negative correlation without delay. Although there was no direct correlation between cAMP and Ca2+, examination of cross correlations using small time windows showed frequent switching behavior from negative to positive and vice versa. Furthermore, spatially asymmetric cAMP and cGMP signals in freely deviating growth cones were visualized directly. These results indicate that we succeed in relating second messenger crosstalk to growth cone deviation and extension, and also indicate the possibility of predicting axon guidance from this second messenger crosstalk.

  18. Nano-scale Topographical Studies on the Growth Cones of Nerve Cells using AFM

    NASA Astrophysics Data System (ADS)

    Durkaya, Goksel; Zhong, Lei; Rehder, Vincent; Dietz, Nikolaus

    2009-11-01

    Nerve cells are the fundamental units which are responsible for intercommunication within the nervous system. The neurites, fibrous cable-like extensions for information delivery, of nerve cells are tipped by highly motile sensory structures known as the growth cones which execute important functions; neural construction, decision making and navigation during development and regeneration of the nervous system. The highly dynamic subcomponents of the growth cones are important in neural activity. Atomic Force Microscopy (AFM) is the most powerful microscopy technique which is capable of imaging without conductivity constraint and in liquid media. AFM providing nano-scale topographical information on biological structures is also informative on the physical properties such as: elasticity, adhesion, and softness. This contribution focuses on AFM analysis of the growth cones of the nerve cells removed from the buccal ganglion of Helisoma trivolvis. The results of nano-scale topography and softness analysis on growth cone central domain, filopodia and overlying lamellopodium (veil) are presented. The subcomponents of the growth cones of different nerve cells are compared to each other. The results of the analysis are linked to the mechanical properties and internal molecular density distribution of the growth cones.

  19. Comparison of sensory neuron growth cone and filopodial responses to structurally diverse aggrecan variants, in vitro

    PubMed Central

    Beller, Justin A.; Kulengowski, Brandon; Kobraei, Edward M.; Curinga, Gabrielle; Calulot, Christopher M.; Bahrami, Azita; Hering, Thomas M.; Snow, Diane M.

    2013-01-01

    Following spinal cord injury, a regenerating neurite encounters a glial scar enriched in chondroitin sulfate proteoglycans (CSPGs), which presents a major barrier. There are two points at which a neurite makes contact with glial scar CSPGs: initially, filopodia surrounding the growth cone extend and make contact with CSPGs, then the peripheral domain of the entire growth cone makes CSPG contact. Aggrecan is a CSPG commonly used to model the effect CSPGs have on elongating or regenerating neurites. In this study, we investigated filopodial and growth cone responses to contact with structurally diverse aggrecan variants using the common stripe assay. Using time-lapse imaging with 15-sec intervals, we measured growth cone area, growth cone width, growth cone length, filopodia number, total filopodia length, and the length of the longest filopodia following contact with aggrecan. Responses were measured after both filopodia and growth cone contact with five different preparations of aggrecan: two forms of aggrecan derived from bovine articular cartilage (purified and prepared using different techniques), recombinant aggrecan lacking chondroitin sulfate side chains (produced in CHO-745 cells) and two additional recombinant aggrecan preparations with varying lengths of chondroitin sulfate side chains (produced in CHO-K1 and COS-7 cells). Responses in filopodia and growth cone behavior differed between the structurally diverse aggrecan variants. Mutant CHO-745 aggrecan (lacking chondroitin sulfate chains) permitted extensive growth across the PG stripe. Filopodia contact with the CHO-745 aggrecan caused a significant increase in growth cone width and filopodia length (112.7% ± 4.9 and 150.9% ± 7.2 respectively, p<0.05), and subsequently upon growth cone contact, growth cone width remained elevated along with a reduction in filopodia number (121.9% ± 4.2; 72.39% ± 6.4, p<0.05). COS-7 derived aggrecan inhibited neurite outgrowth following growth cone contact. Filopodia

  20. Rac1 Modulates Stimulus-evoked Ca2+ Release in Neuronal Growth Cones via Parallel Effects on Microtubule/Endoplasmic Reticulum Dynamics and Reactive Oxygen Species Production

    PubMed Central

    Zhang, Xiao-Feng

    2009-01-01

    The small G protein Rac regulates cytoskeletal protein dynamics in neuronal growth cones and has been implicated in axon growth, guidance, and branching. Intracellular Ca2+ is another well known regulator of growth cone function; however, effects of Rac activity on intracellular Ca2+ metabolism have not been well characterized. Here, we investigate how Rac1 activity affects release of Ca2+ from intracellular endoplasmic reticulum (ER) stores stimulated by application of serotonin (5-hydroxytriptamine). We also address how Rac1 effects on microtubule assembly dynamics affect distribution of Ca2+ release sites. Multimode fluorescent microscopy was used to correlate microtubule and ER behavior, and ratiometric imaging was used to assess intracellular Ca2+ dynamics. We report that Rac1 activity both promotes Ca2+ release and affects its spatial distribution in neuronal growth cones. The underlying mechanism involves synergistic Rac1 effects on microtubule assembly and reactive oxygen species (ROS) production. Rac1 activity modulates Ca2+ by 1) enhancing microtubule assembly which in turn promotes spread of the ER-based Ca2+ release machinery into the growth cone periphery, and 2) by increasing ROS production which facilitated inositol 1,4,5-trisphosphate-dependent Ca2+ release. These results cast Rac1 as a key modulator of intracellular Ca2+ function in the neuronal growth cone. PMID:19570918

  1. Wallenda/DLK protein levels are temporally downregulated by Tramtrack69 to allow R7 growth cones to become stationary boutons.

    PubMed

    Feoktistov, Alexander I; Herman, Tory G

    2016-08-15

    Dual leucine zipper kinase (DLK) promotes growth cone motility and must be restrained to ensure normal development. PHR (Pam/Highwire/RPM-1) ubiquitin ligases therefore target DLK for degradation unless axon injury occurs. Overall DLK levels decrease during development, but how DLK levels are regulated within a developing growth cone has not been examined. We analyzed the expression of the fly DLK Wallenda (Wnd) in R7 photoreceptor growth cones as they halt at their targets and become presynaptic boutons. We found that Wnd protein levels are repressed by the PHR protein Highwire (Hiw) during R7 growth cone halting, as has been observed in other systems. However, as R7 growth cones become boutons, Wnd levels are further repressed by a temporally expressed transcription factor, Tramtrack69 (Ttk69). Previously unobserved negative feedback from JNK also contributes to Wnd repression at both time points. We conclude that neurons deploy additional mechanisms to downregulate DLK as they form stable, synaptic connections. We use live imaging to probe the effects of Wnd and Ttk69 on R7 bouton development and conclude that Ttk69 coordinates multiple regulators of this process. PMID:27402706

  2. Stabilization of actin bundles by a dynamin 1/cortactin ring complex is necessary for growth cone filopodia.

    PubMed

    Yamada, Hiroshi; Abe, Tadashi; Satoh, Ayano; Okazaki, Nana; Tago, Shota; Kobayashi, Kinue; Yoshida, Yumi; Oda, Yoshiya; Watanabe, Masami; Tomizawa, Kazuhito; Matsui, Hideki; Takei, Kohji

    2013-03-01

    Dynamin GTPase, a key molecule in endocytosis, mechanically severs the invaginated membrane upon GTP hydrolysis. Dynamin functions also in regulating actin cytoskeleton, but the mechanisms are yet to be defined. Here we show that dynamin 1, a neuronal isoform of dynamin, and cortactin form ring complexes, which twine around F-actin bundles and stabilize them. By negative-staining EM, dynamin 1-cortactin complexes appeared as "open" or "closed" rings depending on guanine nucleotide conditions. By pyrene actin assembly assay, dynamin 1 stimulated actin assembly in mouse brain cytosol. In vitro incubation of F-actin with both dynamin 1 and cortactin led to the formation of long and thick actin bundles, on which dynamin 1 and cortactin were periodically colocalized in puncta. A depolymerization assay revealed that dynamin 1 and cortactin increased the stability of actin bundles, most prominently in the presence of GTP. In rat cortical neurons and human neuroblastoma cell line, SH-SY5Y, both dynamin 1 and cortactin localized on actin filaments and the bundles at growth cone filopodia as revealed by immunoelectron microscopy. In SH-SY5Y cell, acute inhibition of dynamin 1 by application of dynamin inhibitor led to growth cone collapse. Cortactin knockdown also reduced growth cone filopodia. Together, our results strongly suggest that dynamin 1 and cortactin ring complex mechanically stabilizes F-actin bundles in growth cone filopodia. Thus, the GTPase-dependent mechanochemical enzyme property of dynamin is commonly used both in endocytosis and regulation of F-actin bundles by a dynamin 1-cortactin complex. PMID:23467367

  3. Astrocytic Ca2+ Waves Guide CNS Growth Cones to Remote Regions of Neuronal Activity

    PubMed Central

    Hung, Johanna; Colicos, Michael A.

    2008-01-01

    Activity plays a critical role in network formation during developmental, experience-dependent, and injury related remodeling. Here we report a mechanism by which axon trajectory can be altered in response to remote neuronal activity. Using photoconductive stimulation to trigger high frequency action potentials in rat hippocampal neurons in vitro, we find that activity functions as an attractive cue for growth cones in the local environment. The underlying guidance mechanism involves astrocyte Ca2+ waves, as the connexin-43 antagonist carbenoxolone abolishes the attraction when activity is initiated at a distance greater than 120 µm. The asymmetric growth cone filopodia extension that precedes turning can be blocked with CNQX (10 µM), but not with the ATP and adenosine receptor antagonists suramin (100 µM) and alloxazine (4 µM), suggesting non-NMDA glutamate receptors on the growth cone mediate the interaction with astrocytes. These results define a potential long-range signalling pathway for activity-dependent axon guidance in which growth cones turn towards directional, temporally coordinated astrocyte Ca2+ waves that are triggered by neuronal activity. To assess the viability of the guidance effect in an injury paradigm, we performed the assay in the presence of conditioned media from lipopolysaccharide (LPS) activated purified microglial cultures, as well as directly activating the glia present in our co-cultures. Growth cone attraction was not inhibited under these conditions, suggesting this mechanism could be used to guide regeneration following axonal injury. PMID:19002247

  4. Astrocytic Ca(2+) waves guide CNS growth cones to remote regions of neuronal activity.

    PubMed

    Hung, Johanna; Colicos, Michael A

    2008-01-01

    Activity plays a critical role in network formation during developmental, experience-dependent, and injury related remodeling. Here we report a mechanism by which axon trajectory can be altered in response to remote neuronal activity. Using photoconductive stimulation to trigger high frequency action potentials in rat hippocampal neurons in vitro, we find that activity functions as an attractive cue for growth cones in the local environment. The underlying guidance mechanism involves astrocyte Ca(2+) waves, as the connexin-43 antagonist carbenoxolone abolishes the attraction when activity is initiated at a distance greater than 120 microm. The asymmetric growth cone filopodia extension that precedes turning can be blocked with CNQX (10 microM), but not with the ATP and adenosine receptor antagonists suramin (100 microM) and alloxazine (4 microM), suggesting non-NMDA glutamate receptors on the growth cone mediate the interaction with astrocytes. These results define a potential long-range signalling pathway for activity-dependent axon guidance in which growth cones turn towards directional, temporally coordinated astrocyte Ca(2+) waves that are triggered by neuronal activity. To assess the viability of the guidance effect in an injury paradigm, we performed the assay in the presence of conditioned media from lipopolysaccharide (LPS) activated purified microglial cultures, as well as directly activating the glia present in our co-cultures. Growth cone attraction was not inhibited under these conditions, suggesting this mechanism could be used to guide regeneration following axonal injury. PMID:19002247

  5. Forces from the rear: deformed microtubules in neuronal growth cones influence retrograde flow and advancement

    NASA Astrophysics Data System (ADS)

    Rauch, Philipp; Heine, Paul; Goettgens, Barbara; Käs, Josef A.

    2013-01-01

    The directed motility of growth cones at the tip of neuronal processes is a key function in neuronal path-finding and relies on a complex system of interacting cytoskeletal components. Despite intensive research in this field, many aspects of the mechanical roles of actin structures and, in particular, of microtubules throughout this process remain unclear. Mostly, force generation is ascribed to actin-myosin-based structures such as filopodia bundles and the dynamic polymer gel within the lamellipodium. Our analysis of microtubule buckling and deformation in motile growth cones reveals that extending microtubule filaments contribute significantly to the overall protrusion force. In this study, we establish a relationship of the local variations in stored bending energy and deformation characteristics to growth cone morphology and retrograde actin flow. This implies the relevance of microtubule pushing and deformation for general neurite advancement as well as steering processes.

  6. Structural Mechanism of Allosteric Activity Regulation in a Ribonucleotide Reductase with Double ATP Cones.

    PubMed

    Johansson, Renzo; Jonna, Venkateswara Rao; Kumar, Rohit; Nayeri, Niloofar; Lundin, Daniel; Sjöberg, Britt-Marie; Hofer, Anders; Logan, Derek T

    2016-06-01

    Ribonucleotide reductases (RNRs) reduce ribonucleotides to deoxyribonucleotides. Their overall activity is stimulated by ATP and downregulated by dATP via a genetically mobile ATP cone domain mediating the formation of oligomeric complexes with varying quaternary structures. The crystal structure and solution X-ray scattering data of a novel dATP-induced homotetramer of the Pseudomonas aeruginosa class I RNR reveal the structural bases for its unique properties, namely one ATP cone that binds two dATP molecules and a second one that is non-functional, binding no nucleotides. Mutations in the observed tetramer interface ablate oligomerization and dATP-induced inhibition but not the ability to bind dATP. Sequence analysis shows that the novel type of ATP cone may be widespread in RNRs. The present study supports a scenario in which diverse mechanisms for allosteric activity regulation are gained and lost through acquisition and evolutionary erosion of different types of ATP cone. PMID:27133024

  7. Multiple cone pathways are involved in photic regulation of retinal dopamine

    PubMed Central

    Qiao, Sheng-Nan; Zhang, Zhijing; Ribelayga, Christophe P.; Zhong, Yong-Mei; Zhang, Dao-Qi

    2016-01-01

    Dopamine is a key neurotransmitter in the retina and plays a central role in the light adaptive processes of the visual system. The sole source of retinal dopamine is dopaminergic amacrine cells (DACs). We and others have previously demonstrated that DACs are activated by rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) upon illumination. However, it is still not clear how each class of photosensitive cells generates light responses in DACs. We genetically isolated cone function in mice to specifically examine the cone-mediated responses of DACs and their neural pathways. In addition to the reported excitatory input to DACs from light-increment (ON) bipolar cells, we found that cones alternatively signal to DACs via a retrograde signalling pathway from ipRGCs. Cones also produce ON and light-decrement (OFF) inhibitory responses in DACs, which are mediated by other amacrine cells, likely driven by type 1 and type 2/3a OFF bipolar cells, respectively. Dye injections indicated that DACs had similar morphological profiles with or without ON/OFF inhibition. Our data demonstrate that cones utilize specific parallel excitatory and inhibitory circuits to modulate DAC activity and efficiently regulate dopamine release and the light-adaptive state of the retina. PMID:27356880

  8. Cdc42 and Actin Control Polarized Expression of TI-VAMP Vesicles to Neuronal Growth Cones and Their Fusion with the Plasma MembraneV⃞

    PubMed Central

    Alberts, Philipp; Rudge, Rachel; Irinopoulou, Theano; Danglot, Lydia; Gauthier-Rouvière, Cécile; Galli, Thierry

    2006-01-01

    Tetanus neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP)-mediated fusion of intracellular vesicles with the plasma membrane is crucial for neurite outgrowth, a pathway not requiring synaptobrevin-dependent exocytosis. Yet, it is not known how the TI-VAMP membrane trafficking pathway is regulated or how it is coordinated with cytoskeletal dynamics within the growth cone that guide neurite outgrowth. Here, we demonstrate that TI-VAMP, but not synaptobrevin 2, concentrates in the peripheral, F-actin-rich region of the growth cones of hippocampal neurons in primary culture. Its accumulation correlates with and depends upon the presence of F-actin. Moreover, acute stimulation of actin remodeling by homophilic activation of the adhesion molecule L1 induces a site-directed, actin-dependent recruitment of the TI-VAMP compartment. Expression of a dominant-positive mutant of Cdc42, a key regulator of cell polarity, stimulates formation of F-actin- and TI-VAMP-rich filopodia outside the growth cone. Furthermore, we report that Cdc42 activates exocytosis of pHLuorin tagged TI-VAMP in an actin-dependent manner. Collectively, our data suggest that Cdc42 and regulated assembly of the F-actin network control the accumulation and exocytosis of TI-VAMP-containing membrane vesicles in growth cones to coordinate membrane trafficking and actin remodeling during neurite outgrowth. PMID:16381811

  9. The Role of PI(3,4,5)P3 Signaling During Axonal Growth Cone Chemotaxis

    NASA Astrophysics Data System (ADS)

    Henle, Steven J.

    Development of the nervous system is a remarkably complex process that involves the birth of billions of neurons leading to the formation of trillions of synapses. Many biological programs underlie the formation of a functional nervous system. I focused on trying to understand the process by which a newly formed axon navigates a series of signals in the environment that guide it to a synaptic partner. At the tip of the extending neurite is a conical expansion known as the growth cone that primarily is responsible for performing this pathfinding process. In order to do so it senses the environment, and induces a program of intracellular signaling that in turn leads to directed axon extension. My work has focused on understanding this signaling machinery. I have aimed to understand the role the phosphoinositde PI(3,4,5)P3 due to the critical role it plays in amoeboid chemotaxis. I discovered that PI(3,4,5)P3 and its downstream kinase Akt define the leading edge during growth cone chemotaxis and lead to activation of a TRP (Transient Receptor Potential) channel. Furthermore, I found that the PI(3,4,5)P3 phosphatase PTEN appears to be exclusively linked to guiding growth cone migration in response to a gradient of chemorepellent. Taken together my data demonstrate that PI(3,4,5)P3 functions as a key instructive mediator of growth cone chemotaxis.

  10. Quantitative genetic parameters for yield, plant growth and cone chemical traits in hop (Humulus lupulus L.)

    PubMed Central

    2014-01-01

    Background Most traits targeted in the genetic improvement of hop are quantitative in nature. Improvement based on selection of these traits requires a comprehensive understanding of their inheritance. This study estimated quantitative genetic parameters for 20 traits related to three key objectives for the genetic improvement of hop: cone chemistry, cone yield and agronomic characteristics. Results Significant heritable genetic variation was identified for α-acid and β-acid, as well as their components and relative proportions. Estimates of narrow-sense heritability for these traits (h 2  = 0.15 to 0.29) were lower than those reported in previous hop studies, but were based on a broader suite of families (108 from European, North American and hybrid origins). Narrow-sense heritabilities are reported for hop growth traits for the first time (h 2  = 0.04 to 0.20), relating to important agronomic characteristics such as emergence, height and lateral morphology. Cone chemistry and growth traits were significantly genetically correlated, such that families with more vigorous vegetative growth were associated with lower α-acid and β-acid levels. This trend may reflect the underlying population structure of founder genotypes (European and North American origins) as well as past selection in the Australian environment. Although male and female hop plants are thought to be indistinguishable until flowering, sex was found to influence variation in many growth traits, with male and female plants displaying differences in vegetative morphology from emergence to cone maturity. Conclusions This study reveals important insights into the genetic control of quantitative hop traits. The information gained will provide hop breeders with a greater understanding of the additive genetic factors which affect selection of cone chemistry, yield and agronomic characteristics in hop, aiding in the future development of improved cultivars. PMID:24524684

  11. Making the gradient: Thyroid hormone regulates cone opsin expression in the developing mouse retina

    PubMed Central

    Roberts, Melanie R.; Srinivas, Maya; Forrest, Douglas; Morreale de Escobar, Gabriella; Reh, Thomas A.

    2006-01-01

    Most mammals have two types of cone photoreceptors, which contain either medium wavelength (M) or short wavelength (S) opsin. The number and spatial organization of cone types varies dramatically among species, presumably to fine-tune the retina for different visual environments. In the mouse, S- and M-opsin are expressed in an opposing dorsal–ventral gradient. We previously reported that cone opsin patterning requires thyroid hormone β2, a nuclear hormone receptor that regulates transcription in conjunction with its ligand, thyroid hormone (TH). Here we show that exogenous TH inhibits S-opsin expression, but activates M-opsin expression. Binding of endogenous TH to TRβ2 is required to inhibit S-opsin and to activate M-opsin. TH is symmetrically distributed in the retina at birth as S-opsin expression begins, but becomes elevated in the dorsal retina at the time of M-opsin onset (postnatal day 10). Our results show that TH is a critical regulator of both S-opsin and M-opsin, and suggest that a TH gradient may play a role in establishing the gradient of M-opsin. These results also suggest that the ratio and patterning of cone types may be determined by TH availability during retinal development. PMID:16606843

  12. Rapid Changes in the Translatome during the Conversion of Growth Cones to Synaptic Terminals.

    PubMed

    Zhang, Kelvin Xi; Tan, Liming; Pellegrini, Matteo; Zipursky, S Lawrence; McEwen, Jason M

    2016-02-01

    A common step in the formation of neural circuits is the conversion of growth cones to presynaptic terminals. Characterizing patterns of global gene expression during this process is problematic due to the cellular diversity of the brain and the complex temporal dynamics of development. Here, we take advantage of the synchronous conversion of Drosophila photoreceptor growth cones into presynaptic terminals to explore global changes in gene expression during presynaptic differentiation. Using a tandemly tagged ribosome trap (T-TRAP) and RNA sequencing (RNA-seq) at multiple developmental times, we observed dramatic changes in coding and non-coding RNAs with presynaptic differentiation. Marked changes in the mRNA encoding transmembrane and secreted proteins occurred preferentially. The 3' UTRs of transcripts encoding synaptic proteins were preferentially lengthened, and these extended UTRs were preferentially enriched for sites recognized by RNA binding proteins. These data provide a rich resource for uncovering the regulatory logic underlying presynaptic differentiation. PMID:26832407

  13. Organization of cytoskeletal elements and organelles preceding growth cone emergence from an identified neuron in situ.

    PubMed

    Lefcort, F; Bentley, D

    1989-05-01

    The purpose of this study was to investigate the arrangement of cytoskeletal elements and organelles in an identified neuron in situ at the site of emergence of its growth cone just before and concurrent with the onset of axonogenesis. The Ti1 pioneer neurons are the first pair of afferent neurons to differentiate in embryonic grasshopper limbs. They arise at the distal tip of the limb bud epithelium, the daughter cells of a single precursor cell, the Pioneer Mother Cell (PMC). Using immunohistochemical markers, we characterized the organization of microtubules, centrosomes, Golgi apparatus, midbody, actin filaments, and chromatin from mitosis in the PMC through axonogenesis in the Tils. Just before and concurrent with the onset of axonogenesis, a characteristic arrangement of tubulin, actin filaments, and Golgi apparatus is localized at the proximal pole of the proximal pioneer neuron. The growth cone of the proximal cell stereotypically arises from this site. Although the distal cell's axon generally grows proximally, occasionally it arises from its distal pole; in such limbs, the axons from the sister cells extend from mirror symmetric locations on their somata. In the presence of cytochalasin D, the PMC undergoes nuclear division but not cytokinesis and although other neuronal phenotypes are expressed, axongenesis is inhibited. Our data suggest that intrinsic information determines the site of growth cone emergence of an identified neuron in situ. PMID:2654140

  14. GPCR cell signaling pathways mediating embryonic chick retinal growth cone collapse induced by LPA and S1P

    PubMed Central

    Fincher, Jarod; Whiteneck, Canaan; Birgbauer, Eric

    2014-01-01

    In the development of the nervous system, one of the critical aspects is the proper navigation of axons to their targets, the problem of axonal guidance. We are using the chick visual system as a model to investigate the role of the lysophospholipids lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) as potential axon guidance cues. We show that both LPA and S1P cause specific, dose-dependent growth cone collapse of retinal neurons in vitro in the chick model system, with slight differences to mouse, but very similar to Xenopus. Because LPA and S1P receptors are GPCRs, we analyzed the intracellular signaling pathways using pharmacological inhibitors in chick retinal neurons. Blocking rho kinase (ROCK) prevented growth cone collapse by LPA and S1P, while blocking PLC or chelating calcium had no effect on growth cone collapse. Inhibiting Gi/o with pertussis toxin resulted in a partial reduction of growth cone collapse, both with LPA and S1P. Inhibition of p38 blocked growth cone collapse mediated by LPA but not S1P. Thus, in addition to the involvement of the G12/13-ROCK pathway, LPA and S1P induced collapse of chick retinal growth cones has a partial requirement for Gi/o. PMID:25138637

  15. The discovery of the growth cone and its influence on the study of axon guidance

    PubMed Central

    Tamariz, Elisa; Varela-Echavarría, Alfredo

    2015-01-01

    For over a century, there has been a great deal of interest in understanding how neural connectivity is established during development and regeneration. Interest in the latter arises from the possibility that knowledge of this process can be used to re-establish lost connections after lesion or neurodegeneration. At the end of the XIX century, Santiago Ramón y Cajal discovered that the distal tip of growing axons contained a structure that he called the growth cone. He proposed that this structure enabled the axon’s oriented growth in response to attractants, now known as chemotropic molecules. He further proposed that the physical properties of the surrounding tissues could influence the growth cone and the direction of growth. This seminal discovery afforded a plausible explanation for directed axonal growth and has led to the discovery of axon guidance mechanisms that include diffusible attractants and repellants and guidance cues anchored to cell membranes or extracellular matrix. In this review the major events in the development of this field are discussed. PMID:26029056

  16. The discovery of the growth cone and its influence on the study of axon guidance.

    PubMed

    Tamariz, Elisa; Varela-Echavarría, Alfredo

    2015-01-01

    For over a century, there has been a great deal of interest in understanding how neural connectivity is established during development and regeneration. Interest in the latter arises from the possibility that knowledge of this process can be used to re-establish lost connections after lesion or neurodegeneration. At the end of the XIX century, Santiago Ramón y Cajal discovered that the distal tip of growing axons contained a structure that he called the growth cone. He proposed that this structure enabled the axon's oriented growth in response to attractants, now known as chemotropic molecules. He further proposed that the physical properties of the surrounding tissues could influence the growth cone and the direction of growth. This seminal discovery afforded a plausible explanation for directed axonal growth and has led to the discovery of axon guidance mechanisms that include diffusible attractants and repellants and guidance cues anchored to cell membranes or extracellular matrix. In this review the major events in the development of this field are discussed. PMID:26029056

  17. Automated laser guidance of neuronal growth cones using a spatial light modulator.

    PubMed

    Carnegie, David J; Cizmár, Tomás; Baumgartl, Jörg; Gunn-Moore, Frank J; Dholakia, Kishan

    2009-11-01

    The growth cone of a developing neuron can be guided using a focused infra-red (IR) laser beam [1]. In previous setups this process has required a significant amount of user intervention to adjust continuously the laser beam to guide the growing neuron. Previously, a system using an acousto-optical deflector (AOD) has been developed to steer the beam [2]. However, to enhance the controllability of this system, here we demonstrate the use of a computer controlled spatial light modulator (SLM) to steer and manipulate the shape of a laser beam for use in guided neuronal growth. This new experimental setup paves the way to enable a comprehensive investigation into beam shaping effects on neuronal growth and we show neuronal growth initiated by a Bessel light mode. This is a robust platform to explore the biochemistry of this novel phenomenon. PMID:19705368

  18. Whisker/Cone growth on the thermal control surfaces experiment no. S0069

    NASA Technical Reports Server (NTRS)

    Zwiener, James M.; Coston, James E., Jr.; Miller, Edgar R.; Mell, Richard J.; Wilkes, Donald R.

    1995-01-01

    An unusual surface 'growth' was found during scanning electron microscope (SEM) investigations of the Thermal Control Surface Experiment (TCSE) S0069 front thermal cover. This 'growth' is similar to the cone type whisker growth phenomena as studied by G. K. Wehner beginning in the 1960's. Extensive analysis has identified the most probable composition of the whiskers to be a silicate type glass. Sources of the growth material are outgassing products from the experiment and orbital atomic oxygen, which occurs naturally at the orbital altitudes of the LDEF mission in the form of neutral atomic oxygen. The highly ordered symmetry and directionality of the whiskers are attributed to the long term (5.8 year) stable flight orientation of the LDEF.

  19. Sodium-dependent calcium extrusion and sensitivity regulation in retinal cones of the salamander.

    PubMed Central

    Nakatani, K; Yau, K W

    1989-01-01

    several times higher than in normal Ringer solution. 8. A roughly similar increase in light sensitivity was observed for a rod under the same conditions. 9. We conclude that the Na+-dependent Ca2+ efflux, through lowering intracellular free Ca2+ in the light, has a role in regulating the absolute light sensitivity in cones as it does in rods.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2479741

  20. Ephrin-B2 elicits differential growth cone collapse and axon retraction in retinal ganglion cells from distinct retinal regions

    PubMed Central

    Petros, Timothy J.; Bryson, J. Barney; Mason, Carol

    2010-01-01

    The circuit for binocular vision and stereopsis is established at the optic chiasm, where retinal ganglion cell (RGC) axons diverge into the ipsilateral and contralateral optic tracts. In the mouse retina, ventrotemporal (VT) RGCs express the guidance receptor EphB1, which interacts with the repulsive guidance cue ephrin-B2 on radial glia at the optic chiasm to direct VT RGC axons ipsilaterally. RGCs in the ventral retina also express EphB2, which interacts with ephrin-B2, whereas dorsal RGCs express low levels of EphB receptors. To investigate how growth cones of RGCs from different retinal regions respond upon initial contact with ephrin-B2, we utilized time-lapse imaging to characterize the effects of ephrin-B2 on growth cone collapse and axon retraction in real time. We demonstrate that bath application of ephrin-B2 induces rapid and sustained growth cone collapse and axon retraction in VT RGC axons, whereas contralaterally-projecting dorsotemporal RGCs display moderate growth cone collapse and little axon retraction. Dose response curves reveal that contralaterally-projecting ventronasal axons are less sensitive to ephrin-B2 treatment compared to VT axons. Additionally, we uncovered a specific role for Rho kinase signaling in the retraction of VT RGC axons but not in growth cone collapse. The detailed characterization of growth cone behavior in this study comprises an assay for the study of Eph signaling in RGCs, and provides insight into the phenomena of growth cone collapse and axon retraction in general. PMID:20629048

  1. Mutations in the unfolded protein response regulator ATF6 cause the cone dysfunction disorder achromatopsia.

    PubMed

    Kohl, Susanne; Zobor, Ditta; Chiang, Wei-Chieh; Weisschuh, Nicole; Staller, Jennifer; Gonzalez Menendez, Irene; Chang, Stanley; Beck, Susanne C; Garcia Garrido, Marina; Sothilingam, Vithiyanjali; Seeliger, Mathias W; Stanzial, Franco; Benedicenti, Francesco; Inzana, Francesca; Héon, Elise; Vincent, Ajoy; Beis, Jill; Strom, Tim M; Rudolph, Günther; Roosing, Susanne; Hollander, Anneke I den; Cremers, Frans P M; Lopez, Irma; Ren, Huanan; Moore, Anthony T; Webster, Andrew R; Michaelides, Michel; Koenekoop, Robert K; Zrenner, Eberhart; Kaufman, Randal J; Tsang, Stephen H; Wissinger, Bernd; Lin, Jonathan H

    2015-07-01

    Achromatopsia (ACHM) is an autosomal recessive disorder characterized by color blindness, photophobia, nystagmus and severely reduced visual acuity. Using homozygosity mapping and whole-exome and candidate gene sequencing, we identified ten families carrying six homozygous and two compound-heterozygous mutations in the ATF6 gene (encoding activating transcription factor 6A), a key regulator of the unfolded protein response (UPR) and cellular endoplasmic reticulum (ER) homeostasis. Patients had evidence of foveal hypoplasia and disruption of the cone photoreceptor layer. The ACHM-associated ATF6 mutations attenuate ATF6 transcriptional activity in response to ER stress. Atf6(-/-) mice have normal retinal morphology and function at a young age but develop rod and cone dysfunction with increasing age. This new ACHM-related gene suggests a crucial and unexpected role for ATF6A in human foveal development and cone function and adds to the list of genes that, despite ubiquitous expression, when mutated can result in an isolated retinal photoreceptor phenotype. PMID:26029869

  2. Mutations in the unfolded protein response regulator ATF6 cause the cone dysfunction disorder achromatopsia

    PubMed Central

    Kohl, Susanne; Zobor, Ditta; Chiang, Wei-Chieh; Weisschuh, Nicole; Staller, Jennifer; Menendez, Irene Gonzalez; Chang, Stanley; Beck, Susanne C; Garrido, Marina Garcia; Sothilingam, Vithiyanjali; Seeliger, Mathias W; Stanzial, Franco; Benedicenti, Francesco; Inzana, Francesca; Héon, Elise; Vincent, Ajoy; Beis, Jill; Strom, Tim M; Rudolph, Günther; Roosing, Susanne; den Hollander, Anneke I; Cremers, Frans P M; Lopez, Irma; Ren, Huanan; Moore, Anthony T; Webster, Andrew R; Michaelides, Michel; Koenekoop, Robert K; Zrenner, Eberhart; Kaufman, Randal J; Tsang, Stephen H; Wissinger, Bernd; Lin, Jonathan H

    2015-01-01

    Achromatopsia (ACHM) is an autosomal recessive disorder characterized by color blindness, photophobia, nystagmus and severely reduced visual acuity. Using homozygosity mapping and whole-exome and candidate gene sequencing, we identified ten families carrying six homozygous and two compound-heterozygous mutations in the ATF6 gene (encoding activating transcription factor 6A), a key regulator of the unfolded protein response (UPR) and cellular endoplasmic reticulum (ER) homeostasis. Patients had evidence of foveal hypoplasia and disruption of the cone photoreceptor layer. The ACHM-associated ATF6 mutations attenuate ATF6 transcriptional activity in response to ER stress. Atf6−/− mice have normal retinal morphology and function at a young age but develop rod and cone dysfunction with increasing age. This new ACHM-related gene suggests a crucial and unexpected role for ATF6A in human foveal development and cone function and adds to the list of genes that, despite ubiquitous expression, when mutated can result in an isolated retinal photoreceptor phenotype. PMID:26029869

  3. Semaphorin 3A activates the guanosine triphosphatase Rab5 to promote growth cone collapse and organize callosal axon projections.

    PubMed

    Wu, Kong-Yan; He, Miao; Hou, Qiong-Qiong; Sheng, Ai-Li; Yuan, Lei; Liu, Fei; Liu, Wen-Wen; Li, Guangpu; Jiang, Xing-Yu; Luo, Zhen-Ge

    2014-01-01

    Axon guidance (pathfinding) wires the brain during development and is regulated by various attractive and repulsive cues. Semaphorin 3A (Sema3A) is a repulsive cue, inducing the collapse of axon growth cones. In the mammalian forebrain, the corpus callosum is the major commissure that transmits information flow between the two hemispheres, and contralateral axons assemble into well-defined tracts. We found that the patterning of callosal axon projections in rodent layer II and III (L2/3) cortical neurons in response to Sema3A was mediated by the activation of Rab5, a small guanosine triphosphatase (GTPase) that mediates endocytosis, through the membrane fusion protein Rabaptin-5 and the Rab5 guanine nucleotide exchange factor (GEF) Rabex-5. Rabaptin-5 bound directly to Plexin-A1 in the Sema3A receptor complex [an obligate heterodimer formed by Plexin-A1 and neuropilin 1 (NP1)]; Sema3A enhanced this interaction in cultured neurons. Rabaptin-5 bridged the interaction between Rab5 and Plexin-A1. Sema3A stimulated endocytosis from the cell surface of callosal axon growth cones. In utero electroporation to reduce Rab5 or Rabaptin-5 impaired axon fasciculation or caused mistargeting of L2/3 callosal projections in rats. Overexpression of Rabaptin-5 or Rab5 rescued the defective callosal axon fasciculation or mistargeting of callosal axons caused by the loss of Sema3A-Plexin-A1 signaling in rats expressing dominant-negative Plexin-A1 or in NP1-deficient mice. Thus, our findings suggest that Rab5, its effector Rabaptin-5, and its regulator Rabex-5 mediate Sema3A-induced axon guidance during brain development. PMID:25161316

  4. Semaphorin 3A activates the guanosine triphosphatase Rab5 to promote growth cone collapse and organize callosal axon projections

    PubMed Central

    Wu, Kong-Yan; He, Miao; Hou, Qiong-Qiong; Sheng, Ai-Li; Yuan, Lei; Liu, Fei; Liu, Wen-Wen; Li, Guangpu; Jiang, Xing-Yu; Luo, Zhen-Ge

    2015-01-01

    Axon guidance (pathfinding) wires the brain during development and is regulated by various attractive and repulsive cues. Semaphorin 3A (Sema3A) is a repulsive cue, inducing the collapse of axon growth cones. In the mammalian forebrain, the corpus callosum is the major commissure that transmits information flow between the two hemispheres, and contralateral axons assemble into well-defined tracts. We found that the patterning of callosal axon projections in rodent layer II and III (L2/3) cortical neurons in response to Sema3A was mediated by the activation of Rab5, a small guanosine triphosphatase (GTPase) that mediates endocytosis, through the membrane fusion protein Rabaptin-5 and the Rab5 guanine nucleotide exchange factor (GEF) Rabex-5. Rabaptin-5 bound directly to Plexin-A1 in the Sema3A receptor complex [an obligate heterodimer formed by Plexin-A1 and neuropilin 1 (NP1)]; Sema3A enhanced this interaction in cultured neurons. Rabaptin-5 bridged the interaction between Rab5 and Plexin-A1. Sema3A stimulated endocytosis from the cell surface of callosal axon growth cones. In utero electroporation to reduce Rab5 or Rabaptin-5 impaired axon fasciculation or caused mistargeting of L2/3 callosal projections in rats. Over-expression of Rabaptin-5 or Rab5 rescued the defective callosal axon fasciculation or mistargeting of callosal axons caused by the loss of Sema3A–Plexin-A1 signaling in rats expressing dominant-negative Plexin-A1 or in NP1-deficient mice. Thus, our findings suggest that Rab5, its effector Rabaptin-5, and its regulator Rabex-5 mediate Sema3A-induced axon guidance during brain development. PMID:25161316

  5. Drosophila Ten-m and Filamin Affect Motor Neuron Growth Cone Guidance

    PubMed Central

    Zheng, Lihua; Michelson, Yehudit; Freger, Vita; Avraham, Ziva; Venken, Koen J. T.; Bellen, Hugo J.; Justice, Monica J.; Wides, Ron

    2011-01-01

    The Drosophila Ten-m (also called Tenascin-major, or odd Oz (odz)) gene has been associated with a pair-rule phenotype. We identified and characterized new alleles of Drosophila Ten-m to establish that this gene is not responsible for segmentation defects but rather causes defects in motor neuron axon routing. In Ten-m mutants the inter-segmental nerve (ISN) often crosses segment boundaries and fasciculates with the ISN in the adjacent segment. Ten-m is expressed in the central nervous system and epidermal stripes during the stages when the growth cones of the neurons that form the ISN navigate to their targets. Over-expression of Ten-m in epidermal cells also leads to ISN misrouting. We also found that Filamin, an actin binding protein, physically interacts with the Ten-m protein. Mutations in cheerio, which encodes Filamin, cause defects in motor neuron axon routing like those of Ten-m. During embryonic development, the expression of Filamin and Ten-m partially overlap in ectodermal cells. These results suggest that Ten-m and Filamin in epidermal cells might together influence growth cone progression. PMID:21857973

  6. A hybrid computational model to predict chemotactic guidance of growth cones

    PubMed Central

    Roccasalvo, Iolanda Morana; Micera, Silvestro; Sergi, Pier Nicola

    2015-01-01

    The overall strategy used by growing axons to find their correct paths during the nervous system development is not yet completely understood. Indeed, some emergent and counterintuitive phenomena were recently described during axon pathfinding in presence of chemical gradients. Here, a novel computational model is presented together with its ability to reproduce both regular and counterintuitive axonal behaviours. In this model, the key role of intracellular calcium was phenomenologically modelled through a non standard Gierer-Meinhardt system, as a crucial factor influencing the growth cone behaviour both in regular and complex conditions. This model was able to explicitly reproduce neuritic paths accounting for the complex interplay between extracellular and intracellular environments, through the sensing capability of the growth cone. The reliability of this approach was proven by using quantitative metrics, numerically supporting the similarity between in silico and biological results in regular conditions (control and attraction). Finally, the model was able to qualitatively predict emergent and counterintuitive phenomena resulting from complex boundary conditions. PMID:26086936

  7. A hybrid computational model to predict chemotactic guidance of growth cones

    NASA Astrophysics Data System (ADS)

    Roccasalvo, Iolanda Morana; Micera, Silvestro; Sergi, Pier Nicola

    2015-06-01

    The overall strategy used by growing axons to find their correct paths during the nervous system development is not yet completely understood. Indeed, some emergent and counterintuitive phenomena were recently described during axon pathfinding in presence of chemical gradients. Here, a novel computational model is presented together with its ability to reproduce both regular and counterintuitive axonal behaviours. In this model, the key role of intracellular calcium was phenomenologically modelled through a non standard Gierer-Meinhardt system, as a crucial factor influencing the growth cone behaviour both in regular and complex conditions. This model was able to explicitly reproduce neuritic paths accounting for the complex interplay between extracellular and intracellular environments, through the sensing capability of the growth cone. The reliability of this approach was proven by using quantitative metrics, numerically supporting the similarity between in silico and biological results in regular conditions (control and attraction). Finally, the model was able to qualitatively predict emergent and counterintuitive phenomena resulting from complex boundary conditions.

  8. Retinoic Acid Signaling Regulates Differential Expression of the Tandemly-Duplicated Long Wavelength-Sensitive Cone Opsin Genes in Zebrafish

    PubMed Central

    Frey, Ruth A.; Hunter, Samuel S.; Ashino, Ryuichi; Kawamura, Shoji; Stenkamp, Deborah L.

    2015-01-01

    The signaling molecule retinoic acid (RA) regulates rod and cone photoreceptor fate, differentiation, and survival. Here we elucidate the role of RA in differential regulation of the tandemly-duplicated long wavelength-sensitive (LWS) cone opsin genes. Zebrafish embryos were treated with RA from 48 hours post-fertilization (hpf) to 75 hpf, and RNA was isolated from eyes for microarray analysis. ~170 genes showed significantly altered expression, including several transcription factors and components of cellular signaling pathways. Of interest, the LWS1 opsin gene was strongly upregulated by RA. LWS1 is the upstream member of the tandemly duplicated LWS opsin array and is normally not expressed embryonically. Embryos treated with RA 48 hpf to 100 hpf or beyond showed significant reductions in LWS2-expressing cones in favor of LWS1-expressing cones. The LWS reporter line, LWS-PAC(H) provided evidence that individual LWS cones switched from LWS2 to LWS1 expression in response to RA. The RA signaling reporter line, RARE:YFP indicated that increased RA signaling in cones was associated with this opsin switch, and experimental reduction of RA signaling in larvae at the normal time of onset of LWS1 expression significantly inhibited LWS1 expression. A role for endogenous RA signaling in regulating differential expression of the LWS genes in postmitotic cones was further supported by the presence of an RA signaling domain in ventral retina of juvenile zebrafish that coincided with a ventral zone of LWS1 expression. This is the first evidence that an extracellular signal may regulate differential expression of opsin genes in a tandemly duplicated array. PMID:26296154

  9. R-Type Calcium Channels Are Crucial for Semaphorin 3A–Induced DRG Axon Growth Cone Collapse

    PubMed Central

    Jover, Emmanuel; Bagnard, Dominique; Šatkauskas, Saulius

    2014-01-01

    Semaphorin 3A (Sema3A) is a secreted protein involved in axon path-finding during nervous system development. Calcium signaling plays an important role during axonal growth in response to different guidance cues; however it remains unclear whether this is also the case for Sema3A. In this study we used intracellular calcium imaging to figure out whether Sema3A-induced growth cone collapse is a Ca2+ dependent process. Intracellular Ca2+ imaging results using Fura-2 AM showed Ca2+ increase in E15 mice dorsal root ganglia neurons upon Sema3A treatment. Consequently we analyzed Sema3A effect on growth cones after blocking or modifying intracellular and extracellular Ca2+ channels that are expressed in E15 mouse embryos. Our results demonstrate that Sema3A increased growth cone collapse rate is blocked by the non-selective R- and T- type Ca2+ channel blocker NiCl2 and by the selective R-type Ca2+ channel blocker SNX482. These Ca2+ channel blockers consistently decreased the Sema3A-induced intracellular Ca2+ concentration elevation. Overall, our results demonstrate that Sema3A-induced growth cone collapses are intimately related with increase in intracellular calcium concentration mediated by R-type calcium channels. PMID:25032951

  10. Bidirectional interactions between NOX2-type NADPH oxidase and the F-actin cytoskeleton in neuronal growth cones

    PubMed Central

    Munnamalai, Vidhya; Weaver, Cory J.; Weisheit, Corinne E.; Venkatraman, Prahatha; Agim, Zeynep Sena; Quinn, Mark T.; Suter, Daniel M.

    2014-01-01

    NADPH oxidases are important for neuronal function but detailed subcellular localization studies have not been performed. Here, we provide the first evidence for the presence of functional NOX2-type NADPH oxidase complex in neuronal growth cones and its bidirectional relationship with the actin cytoskeleton. NADPH oxidase inhibition resulted in reduced F-actin content, retrograde F-actin flow, and neurite outgrowth. Stimulation of NADPH oxidase via protein kinase C activation increased levels of hydrogen peroxide in the growth cone periphery. The main enzymatic NADPH oxidase subunit NOX2/gp91phox localized to the growth cone plasma membrane and showed little overlap with the regulatory subunit p40phox. p40phox itself exhibited co-localization with filopodial actin bundles. Differential subcellular fractionation revealed preferential association of NOX2/gp91phox and p40phox with the membrane and the cytoskeletal fraction, respectively. When neurite growth was evoked with beads coated with the cell adhesion molecule apCAM, we observed a significant increase in co-localization of p40phox with NOX2/gp91phox at apCAM adhesion sites. Together, these findings suggest a bidirectional functional relationship between NADPH oxidase activity and the actin cytoskeleton in neuronal growth cones, which contributes to the control of neurite outgrowth. PMID:24702317

  11. [Plant hormones, plant growth regulators].

    PubMed

    Végvári, György; Vidéki, Edina

    2014-06-29

    Plants seem to be rather defenceless, they are unable to do motion, have no nervous system or immune system unlike animals. Besides this, plants do have hormones, though these substances are produced not in glands. In view of their complexity they lagged behind animals, however, plant organisms show large scale integration in their structure and function. In higher plants, such as in animals, the intercellular communication is fulfilled through chemical messengers. These specific compounds in plants are called phytohormones, or in a wide sense, bioregulators. Even a small quantity of these endogenous organic compounds are able to regulate the operation, growth and development of higher plants, and keep the connection between cells, tissues and synergy between organs. Since they do not have nervous and immume systems, phytohormones play essential role in plants' life. PMID:24954142

  12. Deformation and flow of membrane into tethers extracted from neuronal growth cones.

    PubMed Central

    Hochmuth, F M; Shao, J Y; Dai, J; Sheetz, M P

    1996-01-01

    Membrane tethers are extracted at constant velocity from neuronal growth cones using a force generated by a laser tweezers trap. A thermodynamic analysis shows that as the tether is extended, energy is stored in the tether as bending and adhesion energies and in the cell body as "nonlocal" bending. It is postulated that energy is dissipated by three viscous mechanisms including membrane flow, slip between the two monolayers that form the bilayer, and slip between membrane and cytoskeleton. The analysis predicts and the experiments show a linear relation between tether force and tether velocity. Calculations based on the analytical results and the experimental measurements of a tether radius of approximately 0.2 micron and a tether force at zero velocity of approximately 8 pN give a bending modulus for the tether of 2.7 x 10(-19) N.m and an extraordinarily small "apparent surface tension" in the growth cone of 0.003 mN/m, where the apparent surface tension is the sum of the far-field, in-plane tension and the energy of adhesion. Treatments with cytochalasin B and D, ethanol, and nocodazole affect the apparent surface tension but not bending. ATP depletion affects neither, whereas large concentrations of DMSO affect both. Under conditions of flow, data are presented to show that the dominant viscous mechanism comes from the slip that occurs when the membrane flows over the cytoskeleton. ATP depletion and the treatment with DMSO cause a dramatic drop in the effective viscosity. If it is postulated that the slip between membrane and cytoskeleton occurs in a film of water, then this water film has a mean thickness of only approximately 10 A. Images FIGURE 1 FIGURE 4 FIGURE 7 FIGURE 8 PMID:8770212

  13. Corneal Sulfated Glycosaminoglycans and Their Effects on Trigeminal Nerve Growth Cone Behavior In Vitro: Roles for ECM in Cornea Innervation

    PubMed Central

    Schwend, Tyler; Deaton, Ryan J.; Zhang, Yuntao; Caterson, Bruce; Conrad, Gary W.

    2012-01-01

    Purpose. Sensory trigeminal nerve growth cones innervate the cornea in a highly coordinated fashion. The purpose of this study was to determine if extracellular matrix glycosaminoglycans (ECM–GAGs), including keratan sulfate (KS), dermatan sulfate (DS), and chondroitin sulfate A (CSA) and C (CSC), polymerized in developing eyefronts, may provide guidance cues to nerves during cornea innervation. Methods. Immunostaining using antineuron-specific-β-tubulin and monoclonal antibodies for KS, DS, and CSA/C was performed on eyefronts from embryonic day (E) 9 to E14 and staining visualized by confocal microscopy. Effects of purified GAGs on trigeminal nerve growth cone behavior were tested using in vitro neuronal explant cultures. Results. At E9 to E10, nerves exiting the pericorneal nerve ring grew as tight fascicles, advancing straight toward the corneal stroma. In contrast, upon entering the stroma, nerves bifurcated repeatedly as they extended anteriorly toward the epithelium. KS was localized in the path of trigeminal nerves, whereas DS and CSA/C–rich areas were avoided by growth cones. When E10 trigeminal neurons were cultured on different substrates comprised of purified GAG molecules, their neurite growth cone behavior varied depending on GAG type, concentration, and mode of presentation (immobilized versus soluble). High concentrations of immobilized KS, DS, and CSA/C inhibited neurite growth to varying degrees. Neurites traversing lower, permissive concentrations of immobilized DS and CSA/C displayed increased fasciculation and decreased branching, whereas KS caused decreased fasciculation and increased branching. Enzymatic digestion of sulfated GAGs canceled their effects on trigeminal neurons. Conclusions. Data herein suggest that GAGs may direct the movement of trigeminal nerve growth cones innervating the cornea. PMID:23132805

  14. Oxygen Radicals Elicit Paralysis and Collapse of Spinal Cord Neuron Growth Cones upon Exposure to Proinflammatory Cytokines

    PubMed Central

    Kuhn, Thomas B.

    2014-01-01

    A persistent inflammatory and oxidative stress is a hallmark of most chronic CNS pathologies (Alzheimer's (ALS)) as well as the aging CNS orchestrated by the proinflammatory cytokines tumor necrosis factor alpha (TNFα) and interleukin-1 beta (IL-1β). Loss of the integrity and plasticity of neuronal morphology and connectivity comprises an early step in neuronal degeneration and ultimate decline of cognitive function. We examined in vitro whether TNFα or IL-1β impaired morphology and motility of growth cones in spinal cord neuron cultures. TNFα and IL-1β paralyzed growth cone motility and induced growth cone collapse in a dose-dependent manner reflected by complete attenuation of neurite outgrowth. Scavenging reactive oxygen species (ROS) or inhibiting NADPH oxidase activity rescued loss of neuronal motility and morphology. TNFα and IL-1β provoked rapid, NOX-mediated generation of ROS in advancing growth cones, which preceded paralysis of motility and collapse of morphology. Increases in ROS intermediates were accompanied by an aberrant, nonproductive reorganization of actin filaments. These findings suggest that NADPH oxidase serves as a pivotal source of oxidative stress in neurons and together with disruption of actin filament reorganization contributes to the progressive degeneration of neuronal morphology in the diseased or aging CNS. PMID:25050325

  15. Growth of microscopic cones on titanium cathodes of sputter-ion pumps driven by sorption of large argon quantities

    SciTech Connect

    Porcelli, Tommaso; Siviero, Fabrizio; Bongiorno, Gero A.; Michelato, Paolo; Pagani, Carlo

    2015-09-15

    Microscopic cones have been observed on titanium cathodes of sputter-ion pumps (SIPs) after pump operation. The cones were studied by means of scanning electron microscopy and energy dispersive x-ray analysis. Size and morphology of these cones are clearly correlated with the nature and the relative amount of each gas species pumped by each SIP during its working life. In particular, their growth was found to be fed by sputtering mechanisms, mostly during Ar pumping, and to be driven by the electromagnetic field applied to the Penning cells of each SIP. Experimental findings suggest that the formation and extent of such conic structures on cathode surfaces might play a leading role in the onset of phenomena typically related to the functioning of SIPs, e.g., the so-called argon instability.

  16. Val66Met Polymorphism of BDNF Alters Prodomain Structure to Induce Neuronal Growth Cone Retraction

    PubMed Central

    Anastasia, Agustin; Deinhardt, Katrin; Chao, Moses V.; Will, Nathan E.; Irmady, Krithi; Lee, Francis S.; Hempstead, Barbara L.; Bracken, Clay

    2013-01-01

    A common single-nucleotide polymorphism in the human brain-derived neurotrophic factor (BDNF) gene results in a Val66Met substitution in the BDNF prodomain region. This single-nucleotide polymorphism is associated with alterations in memory and with enhanced risk to develop depression and anxiety disorders in humans. Here we show that the isolated BDNF prodomain is detected in the hippocampus and that it can be secreted from neurons in an activity-dependent manner. Using nuclear magnetic resonance spectroscopy and circular dichroism we find that the prodomain is intrinsically disordered, and the Val66Met substitution induces structural changes. Surprisingly, application of Met66 (but not Val66) BDNF prodomain induces acute growth cone retraction and a decrease in Rac activity in hippocampal neurons. Expression of p75NTR and differential engagement of the Met66 prodomain to the SorCS2 receptor are required for this effect. These results identify the Met66 prodomain as a new active ligand which modulates neuronal morphology. PMID:24048383

  17. The Role of Rac1 in the Growth Cone Dynamics and Force Generation of DRG Neurons

    PubMed Central

    Sayyad, Wasim A.; Fabris, Paolo; Torre, Vincent

    2016-01-01

    We used optical tweezers, video imaging, immunocytochemistry and a variety of inhibitors to analyze the role of Rac1 in the motility and force generation of lamellipodia and filopodia from developing growth cones of isolated Dorsal Root Ganglia neurons. When the activity of Rac1 was inhibited by the drug EHop-016, the period of lamellipodia protrusion/retraction cycles increased and the lamellipodia retrograde flow rate decreased; moreover, the axial force exerted by lamellipodia was reduced dramatically. Inhibition of Arp2/3 by a moderate amount of the drug CK-548 caused a transient retraction of lamellipodia followed by a complete recovery of their usual motility. This recovery was abolished by the concomitant inhibition of Rac1. The filopodia length increased upon inhibition of both Rac1 and Arp2/3, but the speed of filopodia protrusion increased when Rac1 was inhibited and decreased instead when Arp2/3 was inhibited. These results suggest that Rac1 acts as a switch that activates upon inhibition of Arp2/3. Rac1 also controls the filopodia dynamics necessary to explore the environment. PMID:26766136

  18. An Automated Strategy for Unbiased Morphometric Analyses and Classifications of Growth Cones In Vitro.

    PubMed

    Chitsaz, Daryan; Morales, Daniel; Law, Chris; Kania, Artur

    2015-01-01

    During neural circuit development, attractive or repulsive guidance cue molecules direct growth cones (GCs) to their targets by eliciting cytoskeletal remodeling, which is reflected in their morphology. The experimental power of in vitro neuronal cultures to assay this process and its molecular mechanisms is well established, however, a method to rapidly find and quantify multiple morphological aspects of GCs is lacking. To this end, we have developed a free, easy to use, and fully automated Fiji macro, Conographer, which accurately identifies and measures many morphological parameters of GCs in 2D explant culture images. These measurements are then subjected to principle component analysis and k-means clustering to mathematically classify the GCs as "collapsed" or "extended". The morphological parameters measured for each GC are found to be significantly different between collapsed and extended GCs, and are sufficient to classify GCs as such with the same level of accuracy as human observers. Application of a known collapse-inducing ligand results in significant changes in all parameters, resulting in an increase in 'collapsed' GCs determined by k-means clustering, as expected. Our strategy provides a powerful tool for exploring the relationship between GC morphology and guidance cue signaling, which in particular will greatly facilitate high-throughput studies of the effects of drugs, gene silencing or overexpression, or any other experimental manipulation in the context of an in vitro axon guidance assay. PMID:26496644

  19. A molecular recognizing system of serotonin in rat fetal axonal growth cones: uptake and high affinity binding.

    PubMed

    Mercado, R; Hernández, J

    1992-09-18

    Axonal growth cone particles (AGCP) isolated from prenatal and postnatal rat brain had different high-affinity 5-HT uptake characteristics. In postnatal AGCP the uptake behaves as in the adult rat brain, while in the prenatal AGCP the uptake characteristics seem to be in a transitional stage. Also in prenatal AGCP we observed specific, high-affinity 5-HT binding sites. These results support the idea of an important role for 5-HT during axogenesis. PMID:1424085

  20. G-protein-coupled receptor cell signaling pathways mediating embryonic chick retinal growth cone collapse induced by lysophosphatidic acid and sphingosine-1-phosphate.

    PubMed

    Fincher, Jarod; Whiteneck, Canaan; Birgbauer, Eric

    2014-01-01

    In the development of the nervous system, one of the critical aspects is the proper navigation of axons to their targets, i.e. the problem of axonal guidance. We used the chick visual system as a model to investigate the role of the lysophospholipids lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) as potential axon guidance cues. We showed that both LPA and S1P cause a specific, dose-dependent growth cone collapse of retinal neurons in vitro in the chick model system, with slight differences compared to the mouse but very similar to observations in Xenopus. Because LPA and S1P receptors are G-protein-coupled receptors, we analyzed the intracellular signaling pathways using pharmacological inhibitors in chick retinal neurons. Blocking rho kinase (ROCK) prevented growth cone collapse by LPA and S1P, while blocking PLC or chelating calcium had no effect on growth cone collapse. Inhibition of Gi/o with pertussis toxin resulted in a partial reduction of growth cone collapse, both with LPA and with S1P. Inhibition of p38 blocked growth cone collapse mediated by LPA but not S1P. Thus, in addition to the involvement of the G12/13-ROCK pathway, LPA- and S1P-induced collapse of chick retinal growth cones has a partial requirement for Gi/o. PMID:25138637

  1. The Rat Homolog of the Schizophrenia Susceptibility Gene ZNF804A Is Highly Expressed during Brain Development, Particularly in Growth Cones

    PubMed Central

    Hinna, Katja Hvid; Rich, Karen; Fex-Svenningsen, Åsa; Benedikz, Eirikur

    2015-01-01

    A single nucleotide polymorphism in the ZNF804A gene, rs1344706, is associated with schizophrenia. The polymorphism has been suggested to alter fetal expression of ZNF804A. It has also been reported to be associated with altered cortical functioning and neural connectivity in the brain. Since developmental mechanisms are suggested in the pathophysiology for schizophrenia, expression of Zfp804A, the rat homolog of ZNF804A, was investigated in the developing rat brain. We found that expression of Zfp804A in most brain regions is developmentally regulated and peaks around birth, where after it decreases towards adult levels. This time point is developmentally the equivalent to the second trimester of fetal development in humans. An exception to this expression pattern is the hippocampus where the expression of Zfp804A appears to increase again in the adult brain. Using laser capture and quantitative PCR we found that Zfp804A mRNA expression in the adult rat hippocampus is highest in the CA1 sub region, where the overall firing rates of neurons is higher than in the CA3 region. In cultured cortical neurons Zfp804A mRNA expression peaked at day 4 and then decreased. The ZFP804A protein expression was therefore investigated with immunochemistry in such cultures. Interestingly, before day 4, the protein is mostly found in the perinuclear region of the cell but at day 4, ZFP804A was instead found throughout the cell and particularly in the growth cones. In conclusion we demonstrate that Zfp804A increases in the rat brain at the time of birth, coinciding with neuronal differentiation. We also show that ZFP804A is localized to growth cones of growing neurites. These data implicate ZFP804A in growth cone function and neurite elongation. The polymorphism rs1344706 lowers expression of ZNF804A during prenatal brain development. This may affect ZNF804A’s role in cone function and neurite elongation leading to synaptic deficits and altered neural connectivity. PMID:26148198

  2. Regulation of muscle growth in neonates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review reports recent findings on the multiple factors that regulate skeletal muscle growth in neonates. Skeletal muscle is the fastest growing protein mass in neonates. The high rate of neonatal muscle growth is due to accelerated rates of protein synthesis accompanied by the rapid accumulatio...

  3. Chemical Growth Regulators for Guayule Plants

    NASA Technical Reports Server (NTRS)

    Dastoor, M. N.; Schubert, W. W.; Petersen, G. R.

    1982-01-01

    Test Tubes containing Guayule - tissue cultures were used in experiments to test effects of chemical-growth regulators. The shoots grew in response to addition of 2-(3,4-dichlorophenoxy)-triethylamine (triethylamine (TEA) derivative) to agar medium. Preliminary results indicate that a class of compounds that promotes growth in soil may also promote growth in a culture medium. Further experiments are needed to define the effect of the TEA derivative.

  4. FGF signalling regulates bone growth through autophagy.

    PubMed

    Cinque, Laura; Forrester, Alison; Bartolomeo, Rosa; Svelto, Maria; Venditti, Rossella; Montefusco, Sandro; Polishchuk, Elena; Nusco, Edoardo; Rossi, Antonio; Medina, Diego L; Polishchuk, Roman; De Matteis, Maria Antonietta; Settembre, Carmine

    2015-12-10

    Skeletal growth relies on both biosynthetic and catabolic processes. While the role of the former is clearly established, how the latter contributes to growth-promoting pathways is less understood. Macroautophagy, hereafter referred to as autophagy, is a catabolic process that plays a fundamental part in tissue homeostasis. We investigated the role of autophagy during bone growth, which is mediated by chondrocyte rate of proliferation, hypertrophic differentiation and extracellular matrix (ECM) deposition in growth plates. Here we show that autophagy is induced in growth-plate chondrocytes during post-natal development and regulates the secretion of type II collagen (Col2), the major component of cartilage ECM. Mice lacking the autophagy related gene 7 (Atg7) in chondrocytes experience endoplasmic reticulum storage of type II procollagen (PC2) and defective formation of the Col2 fibrillary network in the ECM. Surprisingly, post-natal induction of chondrocyte autophagy is mediated by the growth factor FGF18 through FGFR4 and JNK-dependent activation of the autophagy initiation complex VPS34-beclin-1. Autophagy is completely suppressed in growth plates from Fgf18(-/-) embryos, while Fgf18(+/-) heterozygous and Fgfr4(-/-) mice fail to induce autophagy during post-natal development and show decreased Col2 levels in the growth plate. Strikingly, the Fgf18(+/-) and Fgfr4(-/-) phenotypes can be rescued in vivo by pharmacological activation of autophagy, pointing to autophagy as a novel effector of FGF signalling in bone. These data demonstrate that autophagy is a developmentally regulated process necessary for bone growth, and identify FGF signalling as a crucial regulator of autophagy in chondrocytes. PMID:26595272

  5. Mathematics Coursework Regulates Growth in Mathematics Achievement

    ERIC Educational Resources Information Center

    Ma, Xin; Wilkins, Jesse L. M.

    2007-01-01

    Using data from the Longitudinal Study of American Youth (LSAY), we examined the extent to which students' mathematics coursework regulates (influences) the rate of growth in mathematics achievement during middle and high school. Graphical analysis showed that students who started middle school with higher achievement took individual mathematics…

  6. Apoptosis regulates ipRGC spacing necessary for rods and cones to drive circadian photoentrainment

    PubMed Central

    Chen, Shih-Kuo; Chew, Kylie S.; McNeill, David S.; Keeley, Patrick W.; Ecker, Jennifer L.; Mao, Buqing Q.; Pahlberg, Johan; Kim, Bright; Lee, Sammy C. S.; Fox, Michael; Guido, William; Wong, Kwoon Y.; Sampath, Alapakkam P.; Reese, Benjamin E.; Kuruvilla, Rejji; Hattar, Samer

    2012-01-01

    SUMMARY The retina consists of ordered arrays of individual types of neurons for processing vision. Here we show that such order is necessary for intrinsically photosensitive retinal ganglion cells (ipRGCs) to function as irradiance detectors. We found that during development, ipRGCs undergo proximity-dependent Bax-mediated apoptosis. Bax mutant mice exhibit disrupted ipRGC spacing and dendritic stratification with an increase in abnormally localized synapses. ipRGCs are the sole conduit for light input to circadian photoentrainment, and either their melanopsin-based photosensitivity or ability to relay rod-cone input is sufficient for circadian photoentrainment. Remarkably, the disrupted ipRGC spacing does not affect melanopsin-based circadian photoentrainment, but severely impairs rod/cone-driven photoentrainment. We demonstrate reduced rod-cone driven cFos activation and electrophysiological responses in ipRGCs, suggesting that impaired synaptic input to ipRGCs underlies the photoentrainment deficits. Thus, for irradiance detection, developmental apoptosis is necessary for the spacing and connectivity of ipRGCs that underlie their functioning within a neural network. PMID:23395376

  7. Lysophospholipid receptors LPA1–3 are not required for the inhibitory effects of LPA on mouse retinal growth cones

    PubMed Central

    Birgbauer, Eric; Chun, Jerold

    2016-01-01

    One of the major requirements in the development of the visual system is axonal guidance of retinal ganglion cells toward correct targets in the brain. A novel class of extracellular lipid signaling molecules, lysophospholipids, may serve as potential axon guidance cues. They signal through cognate G protein-coupled receptors, at least some of which are expressed in the visual system. Here we show that in the mouse visual system, a lysophospholipid known as lysophosphatidic acid (LPA) is inhibitory to retinal neurites in vitro when delivered extracellularly, causing growth cone collapse and neurite retraction. This inhibitory effect of LPA is both active in the nanomolar range and specific compared to the related lysophospholipid, sphingosine 1-phosphate (S1P). Knockout mice lacking three of the five known LPA receptors, LPA1–3, continue to display retinal growth cone collapse and neurite retraction in response to LPA, demonstrating that these three receptors are not required for these inhibitory effects and indicating the existence of one or more functional LPA receptors expressed on mouse retinal neurites that can mediate neurite retraction. PMID:26966392

  8. Endogenous cholecystokinin regulates growth of human cholangiocarcinoma.

    PubMed Central

    Evers, B M; Gomez, G; Townsend, C M; Rajaraman, S; Thompson, J C

    1989-01-01

    Exogenous administration of cholecystokinin (CCK) or caerulein inhibits growth of SLU-132, a human cholangiocarcinoma that we have shown to possess receptors for CCK. Chronic administration of cholestyramine, a resin that binds bile salts, increases release of CCK and growth of the pancreas in guinea pigs. Feeding the bile salt, taurocholate, inhibits meal-stimulated release of CCK. The purpose of this study was to determine whether endogenous CCK affects growth of the human cholangiocarcinoma, SLU-132. We implanted SLU-132 subcutaneously into athymic nude mice. The bile salt pool was depleted by feeding 4% cholestyramine for 40 days, either alone or enriched with 0.5% taurocholate for 32 days. When the mice were killed, tumors and pancreas were removed. Cholestyramine significantly inhibited the growth of SLU-132 and stimulated growth of the normal pancreas. Feeding of taurocholate acted to stimulate tumor growth. These results demonstrate that endogenous levels of CCK regulate growth of this human cholangiocarcinoma. Our findings suggest that manipulation of levels of endogenous gut hormones may, in the future, play a role in management of patients with certain gastrointestinal cancers. Images Fig. 1. PMID:2476084

  9. In vivo imaging of growth cone and filopodial dynamics: evidence for contact-mediated retraction of filopodia leading to the tiling of sibling processes.

    PubMed

    Baker, Michael W; Macagno, Eduardo R

    2007-02-10

    In the leech embryo, the peripheral comb cell (CC) sends out many nonoverlapping, growth cone-tipped processes that grow in parallel and serve as a scaffold for the migrating myocytes of the later-developing oblique muscle layer. To explore how the parallel arrangement is generated we first examined the arrangement of CC cytoskeletal components by expressing a tubulin-binding protein and actin, both tagged with fluorescent reporters. This revealed that the growth cones were compartmentalized into F-actin-rich filopodia and a microtubule-rich central region. Time-lapse analysis with a 2-photon laser scanning microscope revealed that the growth cones of the CC are highly dynamic, undergoing rapid filopodial extension and retraction. Measurements of filopodial lifespan and length revealed that most filopodia at the leading edge of the growth cone achieved significantly longer lifespans and length than lateral filopodia. Furthermore, for the short-lived lateral filopodia, apparent interaction with a neighboring process was found to be a significant predictor of their nearly immediate (within 2-4 minutes) retraction. When contact was experimentally prevented by ablating individual CCs, the filopodia from the growth cones of adjacent segmental neighbors were found to be significantly lengthened in the direction of the removed homolog. Treatment with low doses of cytochalasin D to disrupt F-actin assembly led to filopodial retraction and growth cone collapse and resulted in the bifurcation of many CC processes, numerous crossover errors, and the loss of parallelism. These findings indicate the existence of a contact-mediated repulsive interaction between processes of the CC. PMID:17177256

  10. Neuroendocrine Regulation of Growth Hormone Secretion.

    PubMed

    Steyn, Frederik J; Tolle, Virginie; Chen, Chen; Epelbaum, Jacques

    2016-01-01

    This article reviews the main findings that emerged in the intervening years since the previous volume on hormonal control of growth in the section on the endocrine system of the Handbook of Physiology concerning the intra- and extrahypothalamic neuronal networks connecting growth hormone releasing hormone (GHRH) and somatostatin hypophysiotropic neurons and the integration between regulators of food intake/metabolism and GH release. Among these findings, the discovery of ghrelin still raises many unanswered questions. One important event was the application of deconvolution analysis to the pulsatile patterns of GH secretion in different mammalian species, including Man, according to gender, hormonal environment and ageing. Concerning this last phenomenon, a great body of evidence now supports the role of an attenuation of the GHRH/GH/Insulin-like growth factor-1 (IGF-1) axis in the control of mammalian aging. © 2016 American Physiological Society. Compr Physiol 6:687-735, 2016. PMID:27065166

  11. The growth and characterization of GaN films on cone-shaped patterned sapphire by MOCVD

    NASA Astrophysics Data System (ADS)

    Liang, Jing; Hongling, Xiao; Xiaoliang, Wang; Cuimei, Wang; Qingwen, Deng; Zhidong, Li; Jieqin, Ding; Zhanguo, Wang; Xun, Hou

    2013-11-01

    GaN films are grown on cone-shaped patterned sapphire substrates (CPSSs) by metal-organic chemical vapor deposition, and the influence of the temperature during the middle stage of GaN growth on the threading dislocation (TD) density of GaN is investigated. High-resolution X-ray diffraction (XRD) and cathode-luminescence (CL) were used to characterize the GaN films. The XRD results showed that the edge-type dislocation density of GaN grown on CPSS is remarkably reduced compared to that of GaN grown on conventional sapphire substrates (CSSs). Furthermore, when the growth temperature in the middle stage of GaN grown on CPSS decreases, the full width at half maximum of the asymmetry (102) plane of GaN is reduced. This reduction is attributed to the enhancement of vertical growth in the middle stage with a more triangular-like shape and the bending of TDs. The CL intensity spatial mapping results also showed the superior optical properties of GaN grown on CPSS to those of GaN on CSS, and that the density of dark spots of GaN grown on CPSS induced by nonradiative recombination is reduced when the growth temperature in the middle stage decreases.

  12. Biochemical properties of Na+/K(+)-ATPase in axonal growth cone particles isolated from fetal rat brain.

    PubMed

    Mercado, R; Hernández, J

    1994-08-01

    Axonal growth cones (AGC) isolated from fetal rat brain have an important specific activity of N+/K(+)-ATPase. Kinetic assays of the enzyme in AGC showed that Km values for ATP or K+ are similar to those reported for the adult brain enzyme. For Na+ the affinity (Km) was lower. Vmax for the three substrates was several times lower in AGC as compared to the adult value. We also observed two apparent inhibition constants of Na+/K(+)-ATPase by ouabain, one of low affinity, possibly corresponding to the alpha 1 isoform and another of high affinity which is different to that described for the alpha 2 isoform of the enzyme. These results support an important role for the sodium pump in the maintainance of volume and cationic balance in neuronal differentiating structures. The functional differences observed also suggest that the enzymatic complex of Na+/K(+)-ATPase in AGC is in a transitional state towards the adult configuration. PMID:7817790

  13. Automated identification of axonal growth cones in time-lapse image sequences.

    PubMed

    Keenan, Thomas M; Hooker, Andrew; Spilker, Mary E; Li, Nianzhen; Boggy, Gregory J; Vicini, Paolo; Folch, Albert

    2006-03-15

    The isolation and purification of axon guidance molecules has enabled in vitro studies of the effects of axon guidance molecule gradients on numerous neuronal cell types. In a typical experiment, cultured neurons are exposed to a chemotactic gradient and their growth is recorded by manual identification of the axon tip position from two or more micrographs. Detailed and statistically valid quantification of axon growth requires evaluation of a large number of neurons at closely spaced time points (e.g. using a time-lapse microscopy setup). However, manual tracing becomes increasingly impractical for recording axon growth as the number of time points and/or neurons increases. We present a software tool that automatically identifies and records the axon tip position in each phase-contrast image of a time-lapse series with minimal user involvement. The software outputs several quantitative measures of axon growth, and allows users to develop custom measurements. For, example analysis of growth velocity for a dissociated E13 mouse cortical neuron revealed frequent extension and retraction events with an average growth velocity of 0.05 +/- 0.14 microm/min. Comparison of software-identified axon tip positions with manually identified axon tip positions shows that the software's performance is indistinguishable from that of skilled human users. PMID:16174535

  14. Process for producing vegetative and tuber growth regulator

    NASA Technical Reports Server (NTRS)

    Stutte, Gary W. (Inventor); Yorio, Neil C. (Inventor)

    1999-01-01

    A process of making a vegetative and tuber growth regulator. The vegetative and tuber growth regulator is made by growing potato plants in a recirculating hydroponic system for a sufficient time to produce the growth regulator. Also, the use of the vegetative and growth regulator on solanaceous plants, tuber forming plants and ornamental seedlings by contacting the roots or shoots of the plant with a sufficient amount of the growth regulator to regulate the growth of the plant and one more of canopy size, plant height, stem length, internode number and presence of tubers in fresh mass. Finally, a method for regulating the growth of potato plants using a recirculating hydroponic system is described.

  15. Fibroblast Growth Factor Signaling in Metabolic Regulation

    PubMed Central

    Nies, Vera J. M.; Sancar, Gencer; Liu, Weilin; van Zutphen, Tim; Struik, Dicky; Yu, Ruth T.; Atkins, Annette R.; Evans, Ronald M.; Jonker, Johan W.; Downes, Michael Robert

    2016-01-01

    The prevalence of obesity is a growing health problem. Obesity is strongly associated with several comorbidities, such as non-alcoholic fatty liver disease, certain cancers, insulin resistance, and type 2 diabetes, which all reduce life expectancy and life quality. Several drugs have been put forward in order to treat these diseases, but many of them have detrimental side effects. The unexpected role of the family of fibroblast growth factors in the regulation of energy metabolism provides new approaches to the treatment of metabolic diseases and offers a valuable tool to gain more insight into metabolic regulation. The known beneficial effects of FGF19 and FGF21 on metabolism, together with recently discovered similar effects of FGF1 suggest that FGFs and their derivatives carry great potential as novel therapeutics to treat metabolic conditions. To facilitate the development of new therapies with improved targeting and minimal side effects, a better understanding of the molecular mechanism of action of FGFs is needed. In this review, we will discuss what is currently known about the physiological roles of FGF signaling in tissues important for metabolic homeostasis. In addition, we will discuss current concepts regarding their pharmacological properties and effector tissues in the context of metabolic disease. Also, the recent progress in the development of FGF variants will be reviewed. Our goal is to provide a comprehensive overview of the current concepts and consensuses regarding FGF signaling in metabolic health and disease and to provide starting points for the development of FGF-based therapies against metabolic conditions. PMID:26834701

  16. Effects of crystallographic plane and co-deposited element on the growth of ion-sputter induced Si nano-cone arrays: a mechanism study

    NASA Astrophysics Data System (ADS)

    Song, Sheng-Chi; Qiu, Ying; Hao, Hong-Chen; Lu, Ming

    2015-06-01

    Self-organized Si nano-cone arrays induced by Ar+ ion sputtering on different Si crystallographic planes with different co-deposited alien atoms are investigated. The Si planes are (100), (110), and (111) ones, and the alien elements are Ta, Mo, Fe, and C, respectively. It is found that the growth of Si nano-cone arrays is insensitive to the initial crystallographic plane, but depends strongly on the co-deposited element. For the same Ar+ ion dose and sample temperature, the smaller the activation energy between the co-deposited element and Si is, the larger the average cone height and base diameter are. It is found that the preferential sputtering does not play an important role in the nano-cone formation. A model based on the concepts of classical surface-curvature-dependent sputtering yield and the formation of stationary silicide is proposed, which explains the observed results. The results of microstructural and compositional analysis support the proposed model.

  17. Differentiation of neuronal growth cones: specialization of filopodial tips for adhesive interactions.

    PubMed Central

    Tsui, H C; Lankford, K L; Klein, W L

    1985-01-01

    Adhesive contacts made by filopodia of developing neurons are important in neurite growth and in the formation of synaptic junctions. In the present work, filopodial interactions of cultured chicken retina neurons were studied by using video-enhanced contrast, differential interference contrast (VEC-DIC) microscopy and the high-voltage electron microscope (HVEM). Use of the HVEM to examine whole mounts of fixed cells showed that filopodia in older cultures developed an appearance that might be expected of nascent synapses, becoming enlarged at their endings and accumulating organelles resembling synaptic vesicles. VEC-DIC microscopy, used to observe the motility and adhesive properties of filopodia in living cells, showed there was a particularly high affinity between filopodia tips. Contacting filopodia typically repositioned themselves so they could attach at a tip-to-tip position, occasionally bending as much as 90 degrees to achieve this preferred orientation. Interacting filopodia frequently remained together as they pushed or pulled on each other, moved laterally together, or stretched tightly and underwent intense vibratory movements. Such linked motility occurred even when apparent gaps existed between the filopodia. Examination of these gaps with the HVEM revealed filamentous structures linking the apposed membranes. The filamentous links were 10-13 nm in diameter and 30-100 nm long. Although it has not yet been established that the filaments reflect the native configuration of the interconnecting materials, the structures seem likely to be associated with the strongly adhesive behavior of the filopodial tips. The possible significance of these structural and functional properties of filopodia tips to axon growth and synapse formation is discussed. Images PMID:3865227

  18. The Disruption of the Cytoskeleton during Semaphorin 3A induced Growth Cone Collapse Correlates with Differences in Actin Organization and Associated Binding Proteins

    PubMed Central

    Brown, Jacquelyn A; Bridgman, Paul C

    2010-01-01

    Repulsive guidance cues induce growth cone collapse or collapse and retraction. Collapse results from disruption and loss of the actin cytoskeleton. Actin rich regions of growth cones contain binding proteins that influence filament organization, such as Arp2/3, cortactin, and fascin, but little is known about the role that these proteins play in collapse. Here we show that Semaphorin 3A (Sema 3A), which is repulsive to mouse dorsal root ganglion neurons, has unequal effects on actin binding proteins and their associated filaments. The immunofluorescence staining intensity of Arp-2 and cortactin decreases relative to total protein, while in unextracted growth cones fascin increases. Fascin and myosin IIB staining redistribute and show increased overlap. The degree of actin filament loss during collapse correlates with filament superstructures detected by rotary shadow electron microscopy. Collapse results in the loss of branched f-actin meshworks, while actin bundles are partially retained to varying degrees. Taken together with the known affects of Sema 3A on actin, this suggests a model for collapse that follows a sequence; depolymerization of actin meshworks followed by partial depolymerization of fascin associated actin bundles and their movement to the neurite to complete collapse. The relocated fascin associated actin bundles may provide the substrate for actomyosin contractions that produce retraction. PMID:19513995

  19. Cone Heads

    ERIC Educational Resources Information Center

    Coy, Mary

    2005-01-01

    The author, a middle school art teacher, describes a sculpture project lesson involving Cone Heads (sculptures made from cardboard cones). Discussion of caricatures with exaggerated facial features and interesting profiles helped students understand that the more expressive the face, the better. This project took approximately four to five…

  20. Expression of Wnt Receptors in Adult Spiral Ganglion Neurons: Frizzled 9 Localization at Growth Cones of Regenerating Neurites

    PubMed Central

    Shah, S. M.; Kang, Y.-J.; Christensen, B. L.; Feng, A. S.; Kollmar, R.

    2009-01-01

    Little is known about signaling pathways, besides those of neurotrophic factors, that are operational in adult spiral ganglion neurons. In patients with sensorineural hearing loss, such pathways could eventually be targeted to stimulate and guide neurite outgrowth from the remnants of the spiral ganglion towards a cochlear implant, thereby improving the fidelity of sound transmission. To systematically identify neuronal receptors for guidance cues in the adult cochlea, we conducted a genome-wide cDNA microarray screen with two-month-old CBA/CaJ mice. A meta-analysis of our data and those from older mice in two other studies revealed the presence of neuronal transmembrane receptors that represent all four established guidance pathways—ephrin, netrin, semaphorin, and slit—in the mature cochlea as late as 15 months. In addition, we observed the expression of all known receptors for the Wnt morphogens, whose neuronal guidance function has only recently been recognized. In situ hybridizations located the mRNAs of the Wnt receptors frizzled 1, 4, 6, 9, and 10 specifically in adult spiral ganglion neurons. Finally, frizzled 9 protein was found in the growth cones of adult spiral ganglion neurons that were regenerating neurites in culture. We conclude from our results that adult spiral ganglion neurons are poised to respond to neurite damage, owing to the constitutive expression of a large and diverse collection of guidance receptors. Wnt signaling, in particular, emerges as a candidate pathway for guiding neurite outgrowth towards a cochlear implant after sensorineural hearing loss. PMID:19716861

  1. Observing scoria cone growth and lava flow development in the Bocca Nuova crater, Mount Etna, Sicily (2012), using repeat terrestrial laser scanner measurements

    NASA Astrophysics Data System (ADS)

    Slatcher, N.; James, M. R.; Calvari, S.; Ganci, G.; Browning, J.

    2012-12-01

    In July 2012, following the cessation of the 2011 - 2012 sequence of fire fountaining events from the flanks of the South East crater, magmatic activity began in the Bocca Nuova summit crater of Mount Etna (Sicily). The activity was characterised by mild Strombolian explosions and gentle lava effusion, and began constructing a small scoria cone within the crater. Here, we present analysis of a sequence of terrestrial laser scans, time-lapse camera and satellite data that captured scoria cone growth and lava flow development between 17 - 21 July, 2012. Activity over the observation period comprised Strombolian explosions at a recurrence interval of ~1 - 10 seconds, and a short lava flow (approximately 20 m wide and 120 m long) emanating from the vent region. On 17, 19 and 21 July, a Riegl LPM-321 terrestrial laser scanner (TLS) was deployed on the western rim of the Bocca Nuova, ~350m from the active vent and used to capture a single scan on each day to cover the cone, lava flow and crater wall. High-resolution digital elevation models (DEMs) derived from these scans were used to calculate volumetric change and growth rate of the cone. A maximum elevation gain of ~15 m and an increase in volume of ~84000 m3 (equivalent to 0.24 m3s-1) was observed over the four-day period. The lava flow was also repeatedly scanned at 10-minute intervals over a 90-minute period on 21 July. By combining these TLS data with concurrently collected thermal and visual imagery, a detailed time-series analysis of flow velocities and decimetric topographic changes will be used to assess lava flux and estimate rheological properties.

  2. Endocrine Regulation of Compensatory Growth in Fish

    PubMed Central

    Won, Eugene T.; Borski, Russell J.

    2013-01-01

    Compensatory growth (CG) is a period of accelerated growth that occurs following the alleviation of growth-stunting conditions during which an organism can make up for lost growth opportunity and potentially catch up in size with non-stunted cohorts. Fish show a particularly robust capacity for the response and have been the focus of numerous studies that demonstrate their ability to compensate for periods of fasting once food is made available again. CG is characterized by an elevated growth rate resulting from enhanced feed intake, mitogen production, and feed conversion efficiency. Because little is known about the underlying mechanisms that drive the response, this review describes the sequential endocrine adaptations that lead to CG; namely during the precedent catabolic phase (fasting) that taps endogenous energy reserves, and the following hyperanabolic phase (refeeding) when accelerated growth occurs. In order to elicit a CG response, endogenous energy reserves must first be moderately depleted, which alters endocrine profiles that enhance appetite and growth potential. During this catabolic phase, elevated ghrelin and growth hormone (GH) production increase appetite and protein-sparing lipolysis, while insulin-like growth factors (IGFs) are suppressed, primarily due to hepatic GH resistance. During refeeding, temporal hyperphagia provides an influx of energy and metabolic substrates that are then allocated to somatic growth by resumed IGF signaling. Under the right conditions, refeeding results in hyperanabolism and a steepened growth trajectory relative to constantly fed controls. The response wanes as energy reserves are re-accumulated and homeostasis is restored. We ascribe possible roles for select appetite and growth-regulatory hormones in the context of the prerequisite of these catabolic and hyperanabolic phases of the CG response in teleosts, with emphasis on GH, IGFs, cortisol, somatostatin, neuropeptide Y, ghrelin, and leptin. PMID:23847591

  3. Endocrine regulation of longitudinal bone growth.

    PubMed

    Wit, Jan M; Camacho-Hübner, Cecilia

    2011-01-01

    Longitudinal growth is primarily influenced by the GH-IGF-I axis, which is a mixed endocrine-paracrine-autocrine system. Further, classical hormones such as thyroxine, glucocorticosteroids and sex steroids play a role, as well as primarily paracrine systems. In the GH-IGF-I axis, seven disorders can be differentiated: (1) GH deficiency; (2) GHR defects; (3) defects in the GH signal transduction pathway; (4) IGF1 defects; (5) IGFALS defects; (6) IGF1R defects, and (7) IGF2 defects. Children with one of the first 3 disorders have near-normal prenatal growth, while children with defects of IGF1, IGF1R or IGF2 show prenatal as well as postnatal growth retardation. Hypothyroidism or a thyroid hormone resistance cause growth failure, but the effect of hyperthyroidism on growth is modest. Hypercortisolism causes poor growth, while FGD caused by ACTH insensitivity is associated with tall stature. Increased sex steroids in childhood cause advanced growth but even more skeletal maturation, so that adult height is decreased. Finally, the paracrine-autocrine SHOX-BNP pathway and the related CNP-NPR2 pathway are also involved in growth, as very many other growth factors and their receptors and mediators. PMID:21865752

  4. Surface Orientation Affects the Direction of Cone Growth by Leptolyngbya sp. Strain C1, a Likely Architect of Coniform Structures Octopus Spring (Yellowstone National Park)

    PubMed Central

    Reyes, Kristina; Gonzalez, Nicolas I.; Stewart, Joshua; Ospino, Frank; Nguyen, Dickie; Cho, David T.; Ghahremani, Nahal; Spear, John R.

    2013-01-01

    Laminated, microbially produced stromatolites within the rock record provide some of the earliest evidence for life on Earth. The chemical, physical, and biological factors that lead to the initiation of these organosedimentary structures and shape their morphology are unclear. Modern coniform structures with morphological features similar to stromatolites are found on the surface of cyanobacterial/microbial mats. They display a vertical element of growth, can have lamination, can be lithified, and observably grow with time. To begin to understand the microbial processes and interactions required for cone formation, we determined the phylogenetic composition of the microbial community of a coniform structure from a cyanobacterial mat at Octopus Spring, Yellowstone National Park, and reconstituted coniform structures in vitro. The 16S rRNA clone library from the coniform structure was dominated by Leptolyngbya sp. Other cyanobacteria and heterotrophic bacteria were present in much lower abundance. The same Leptolyngbya sp. identified in the clone library was also enriched in the laboratory and could produce cones in vitro. When coniform structures were cultivated in the laboratory, the initial incubation conditions were found to influence coniform morphology. In addition, both the angle of illumination and the orientation of the surface affected the angle of cone formation demonstrating how external factors can influence coniform, and likely, stromatolite morphology. PMID:23241986

  5. Gαz regulates BDNF-induction of axon growth in cortical neurons

    PubMed Central

    Hultman, Rainbo; Kumari, Udhaya; Michel, Nadine; Casey, Patrick J.

    2014-01-01

    The disruption of neurotransmitter and neurotrophic factor signaling in the central nervous system (CNS) is implicated as the root cause of neuropsychiatric disorders, including schizophrenia, epilepsy, chronic pain, and depression. Therefore, identifying the underlying molecular mechanisms by which neurotransmitter and neurotrophic factor signaling regulates neuronal survival or growth may facilitate identification of more effective therapies for these disorders. Previously, our lab found that the heterotrimeric G protein, Gz, mediates crosstalk between G protein-coupled receptors and neurotrophin signaling in the neural cell line PC12. These data, combined with Gαz expression profiles - predominantly in neuronal cells with higher expression levels corresponding to developmental times of target tissue innervation - suggested that Gαz may play an important role in neurotrophin signaling and neuronal development. Here, we provide evidence in cortical neurons, both manipulated ex vivo and those cultured from Gz knockout mice, that Gαz is localized to axonal growth cones and plays a significant role in the development of axons of cortical neurons in the CNS. Our findings indicate that Gαz inhibits BDNF-stimulated axon growth in cortical neurons, establishing an endogenous role for Gαz in regulating neurotrophin signaling in the CNS. PMID:24321455

  6. Triennial Growth Symposium: Dietary regulation of growth development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The 2010 Triennial Growth Symposium was held immediately before the Joint Annual Meeting of the American Dairy Science Association, Poultry Science Association, Asociación Mexicana de Producción Animal, Canadian Society of Animal Science, Western Section American Society of Animal Science, and Ameri...

  7. Recent Insights into the Regulation of the Growth Plate

    PubMed Central

    Lui, Julian C.; Nilsson, Ola; Baron, Jeffrey

    2014-01-01

    For most bones, elongation is driven primarily by chondrogenesis at the growth plates. This process results from chondrocyte proliferation, hypertrophy, and extracellular matrix secretion and is carefully orchestrated by complex networks of local paracrine factors and modulated by endocrine factors. We review here recent advances in the understanding of growth plate physiology. These advances include new approaches to study expression patterns of large numbers of genes in the growth plate, using microdissection followed by microarray. This approach has been combined with genome-wide association studies to provide insights into the regulation of the human growth plate. We also review recent studies elucidating the roles of bone morphogenetic proteins, fibroblast growth factors, C-type natriuretic peptide, and suppressor of cytokine signaling in the local regulation of growth plate chondrogenesis and longitudinal bone growth. PMID:24740736

  8. Anillin Regulates Neuronal Migration and Neurite Growth by Linking RhoG to the Actin Cytoskeleton.

    PubMed

    Tian, Dong; Diao, Min; Jiang, Yuxiang; Sun, Lingfei; Zhang, Yan; Chen, Zhucheng; Huang, Shanjin; Ou, Guangshuo

    2015-05-01

    Neuronal migration and neurite growth are essential events in neural development, but it remains unclear how guidance cues are transduced through receptors to the actin cytoskeleton, which powers these processes. We report that a cytokinetic scaffold protein, Anillin, is redistributed to the leading edge of the C. elegans Q neuroblast during cell migration and neurite growth. To bypass the requirement for Anillin in cytokinesis, we used the somatic CRISPR-Cas9 technique to generate conditional mutations in Anillin. We demonstrate that Anillin regulates cell migration and growth cone extension by stabilizing the F-actin network at the leading edge. Our biochemical analysis shows that the actin-binding domain of Anillin is sufficient to stabilize F-actin by antagonizing the F-actin severing activity of Cofilin. We further uncover that the active form of RhoG/MIG-2 directly binds to Anillin and recruits it to the leading edge. Our results reveal a novel pathway in which Anillin transduces the RhoG signal to the actin cytoskeleton during neuronal migration and neurite growth. PMID:25843030

  9. Osmotic regulation of seamless tube growth.

    PubMed

    Schottenfeld-Roames, Jodi; Ghabrial, Amin S

    2013-02-01

    Most organs are composed of tubes of differing cellular architectures, including intracellular 'seamless' tubes. Two studies examining the morphogenesis of the seamless tubes formed by the excretory canal cell in Caenorhabditis elegans reveal a previously unappreciated role for osmoregulation of tubulogenesis: hyperosmotic shock recruits canalicular vesicles to the lumenal membrane to promote seamless tube growth. PMID:23377027

  10. Mechanical regulation of plant growth and development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.

    1984-01-01

    Soybean and eggplant grown and shaken in a greenhouse exhibited decreased internode length, internode diameter, leaf area, and fresh and dry weight of roots and shoots in much the same way as outdoor-exposed plants. Perhaps more important than decreased dimensions of plant parts resulting from periodic seismic treatment is the inhibition of photosynthetic productivity that accompanies this stress. Soybeam plants briefly shaken or rubbed twice daily experienced a decrease in relative as well as absolute growth rate compared to that of undisturbed controls. Growth dynamics analysis revealed that virtually all of the decline in relative growth rate (RGR) was due to a decline in net assimilation rate (NAR), but not in leaf area ratio (LAR). Lower NAR suggests that the stress-induced decrease in dry weight gain is due to a decline in photosynthetic efficiency. Possible effects on stomatal aperture was investigated by measuring rates of whole plant transpiration as a function of seismo-stress, and a transitory decrease followed by a gradual, partial recovery was detected.

  11. Growth Regulator Herbicides Prevent Invasive Annual Grass Seed Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Auxinic herbicides, such as 2,4-D and dicamba, that act as plant growth regulators are commonly used for broadleaf weed control in cereal crops (e.g. wheat, barley), grasslands, and non-croplands. If applied at later growth stages, while cereals are developing reproductive parts, the herbicides can...

  12. Cytosolic pH: A conserved regulator of cell growth?

    PubMed Central

    Dechant, Reinhard; Peter, Matthias

    2014-01-01

    Although target of rapamycin (TOR) kinase and Ras are central regulators of cell growth in yeast and mammals, the molecular mechanisms underlying their regulation by nutrients are still poorly understood. Interestingly, recent studies identified cytosolic pH as a critical regulatory signal for both pathways, which might have widespread implications for tumor cell biology PMID:27308377

  13. ADVANCES IN INTEGRATING INSECT GROWTH REGULATORS INTO STORAGE PEST MANAGEMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect growth regulators (IGRs) are insecticides that mimic insect-produced hormones that regulate the developmental process. They generally have little or no mammalian toxicity, and are considered reduced-risk insecticides that are often exempt from tolerance requirements of regulatory agencies. Al...

  14. Light signaling and the phytohormonal regulation of shoot growth.

    PubMed

    Kurepin, Leonid V; Pharis, Richard P

    2014-12-01

    Shoot growth of dicot plants is rigorously controlled by the interactions of environmental cues with several groups of phytohormones. The signaling effects of light on shoot growth are of special interest, as both light irradiance and light quality change rapidly throughout the day, causing profound changes in stem elongation and leaf area growth. Among the several dicot species examined, we have focused on sunflower (Helianthus annuus L.) because its shoots are robust and their growth is highly plastic. Sunflower shoots thus constitute an ideal tissue for assessing responses to both light irradiance and light quality signals. Herein, we discuss the possible roles of gibberellins, auxin, ethylene, cytokinins and brassinosteroids in mediating the stem elongation and leaf area growth that is induced by shade light. To do this we uncoupled the plant's responses to changes in the red to far-red [R/FR] light ratio from its responses to changes in irradiance of photosynthetically active radiation [PAR]. Reducing each of R/FR light ratio and PAR irradiance results in increased sunflower stem elongation. However, the plant's response for leaf area growth differs considerably, with a low R/FR ratio generally promoting leaf area growth, whereas low irradiance PAR inhibits it. The increased stem elongation that occurs in response to lowering R/FR ratio and PAR irradiance is accomplished at the expense of leaf area growth. In effect, the low PAR irradiance signal overrides the low R/FR ratio signal in shade light's control of leaf growth and development. Three hormone groups, gibberellins, auxin and ethylene are directly involved in regulating these light-mediated shoot growth changes. Gibberellins and auxin function as growth promoters, with auxin likely acting as an up-regulator of gibberellin biosynthesis. Ethylene functions as a growth-inhibitor and probably interacts with gibberellins in regulating both stem and leaf growth of the sunflower shoot. PMID:25443853

  15. ESCRT-II controls retinal axon growth by regulating DCC receptor levels and local protein synthesis

    PubMed Central

    Konopacki, Filip A.; Dwivedy, Asha; Bellon, Anaïs; Blower, Michael D.

    2016-01-01

    Endocytosis and local protein synthesis (LPS) act coordinately to mediate the chemotropic responses of axons, but the link between these two processes is poorly understood. The endosomal sorting complex required for transport (ESCRT) is a key regulator of cargo sorting in the endocytic pathway, and here we have investigated the role of ESCRT-II, a critical ESCRT component, in Xenopus retinal ganglion cell (RGC) axons. We show that ESCRT-II is present in RGC axonal growth cones (GCs) where it co-localizes with endocytic vesicle GTPases and, unexpectedly, with the Netrin-1 receptor, deleted in colorectal cancer (DCC). ESCRT-II knockdown (KD) decreases endocytosis and, strikingly, reduces DCC in GCs and leads to axon growth and guidance defects. ESCRT-II-depleted axons fail to turn in response to a Netrin-1 gradient in vitro and many axons fail to exit the eye in vivo. These defects, similar to Netrin-1/DCC loss-of-function phenotypes, can be rescued in whole (in vitro) or in part (in vivo) by expressing DCC. In addition, ESCRT-II KD impairs LPS in GCs and live imaging reveals that ESCRT-II transports mRNAs in axons. Collectively, our results show that the ESCRT-II-mediated endocytic pathway regulates both DCC and LPS in the axonal compartment and suggest that ESCRT-II aids gradient sensing in GCs by coupling endocytosis to LPS. PMID:27248654

  16. Multiple Transcription Factor Families Regulate Axon Growth and Regeneration

    PubMed Central

    Moore, Darcie L.; Goldberg, Jeffrey L.

    2011-01-01

    Understanding axon regenerative failure remains a major goal in neuroscience, and reversing this failure remains a major goal for clinical neurology. While an inhibitory CNS environment clearly plays a role, focus on molecular pathways within neurons has begun to yield fruitful insights. Initial steps forward investigated the receptors and signaling pathways immediately downstream of environmental cues, but recent work has also shed light on transcriptional control mechanisms that regulate intrinsic axon growth ability, presumably through whole cassettes of gene target regulation. Here we will discuss transcription factors that regulate neurite growth in vitro and in vivo, including p53, SnoN, E47, CREB, STAT3, NFAT, c-Jun, ATF3, Sox11, NFκB, and Kruppel-like factors (KLFs). Revealing the similarities and differences among the functions of these transcription factors may further our understanding of the mechanisms of transcriptional regulation in axon growth and regeneration. PMID:21674813

  17. Angiogenic growth factor axis in autophagy regulation.

    PubMed

    Stanton, Marissa J; Dutta, Samikshan; Polavaram, Navatha Shree; Roy, Sohini; Muders, Michael H; Datta, Kaustubh

    2013-05-01

    Understanding the molecular mechanisms promoting therapy resistance is important. Previously, we reported that VEGFC can promote cancer cell survival during stress via interaction with its receptor NRP2. While examining the molecular mechanisms involved in this survival, we performed a microarray study in which we identified two genes, WDFY1 and LAMP2, which have been suggested to function in autophagy. Our subsequent studies further confirmed the regulation of autophagy by the VEGFC-NRP2 axis in cancer during starvation- and chemotherapy-induced stress. We are currently in the process of determining the mechanism(s) through which WDFY1 and LAMP2 control autophagy; however, we did observe an increase in MTOR complex 1 (MTORC1) activity after the depletion of the VEGFC-NRP2 axis. It would therefore be interesting to study whether WDFY1 and LAMP2 can influence MTORC1 activity and regulate autophagy. Taken together, our data suggest that targeting the VEGFC-NRP2 axis in combination with chemotherapy could be an effective treatment for advanced cancers. PMID:23388383

  18. [Debt, regulations and economic growth in Mexico].

    PubMed

    Vélez-Fernández Varela, F

    1989-01-01

    In the Mexican economy four policies forced the State to redefine its strategy of development. They were: 1) the considerable purchase by the government of firms that were not strategic or of national priority; 2) the preservation of a structure of high industrial protection; 3) an excessive reliance of the economy on oil, and 4) the perception of the increase in the price of oil as a permanent and not a temporary phenomenon. By the seventies the first two phenomena restricted the possibilities of economic growth which translated into inflation. In the eighties the high dependency on oil and the weakness of its monetary value deepened those trends. The external debt became the single most significant constraint of development. The government was forced to reduce drastically substantive public expenditure. Health was one of the areas more severely affected. PMID:2662429

  19. Periconceptional events perturb postnatal growth regulation in sheep.

    PubMed

    Jaquiery, Anne L; Oliver, Mark H; Bloomfield, Frank H; Harding, Jane E

    2011-09-01

    Periconceptional undernutrition and twin conception alter intrauterine growth and metabolism and are associated with later adverse metabolic outcomes. The contribution of postnatal growth to these outcomes is less well defined. We investigated whether maternal periconceptional undernutrition or twin conception altered postnatal growth regulation in ways that could lead to metabolic disease. Single and twin offspring of ewes undernourished (UN) from 61 d before until 30 d after mating, fed to achieve and maintain 10-15% weight loss (UN), were compared with offspring of maintenance-fed controls (N). At 2 h and 1, 6, and 12 wk after birth, lambs were weighed and plasma hormone and metabolite concentrations analyzed. Milk intake, measured by deuterium oxide dilution, was inversely related to birth weight only in N singles, although twins had the greatest postnatal growth velocity. Positive associations were seen between milk intake, growth velocity, and leptin concentrations in N, but not UN, offspring. We conclude that periconceptional undernutrition alters the relationships between regulators of postnatal growth, including nutrient intake and key hormonal axes, in both singles and twins without affecting size at birth or postnatal growth velocity. Dissociation of growth from its key regulators is one possible mechanism underlying adverse metabolic outcomes after periconceptional undernutrition. PMID:21587096

  20. Growth factors in critical illness: regulation and therapeutic aspects.

    PubMed

    Frost, R A; Lang, C H

    1998-03-01

    The erosion of lean body mass observed during catabolic illness is still a major cause of morbidity and mortality. The known anabolic actions of growth hormone and insulin-like growth factor-I have stimulated interest in the use of these agents to mitigate the loss of muscle protein after injury. This review summarizes advances in our understanding of how nutrition, hormones and proinflammatory cytokines regulate the somatotropic axis in health and disease, and recent studies involving the use of growth hormone or insulin-like growth factor-I in the treatment of critically ill patients. PMID:10565348

  1. The neglected role of insulin-like growth factors in the maternal circulation regulating fetal growth

    PubMed Central

    Sferruzzi-Perri, A N; Owens, J A; Pringle, K G; Roberts, C T

    2011-01-01

    Maternal insulin-like growth factors (IGFs) play a pivotal role in modulating fetal growth via their actions on both the mother and the placenta. Circulating IGFs influence maternal tissue growth and metabolism, thereby regulating nutrient availability for the growth of the conceptus. Maternal IGFs also regulate placental morphogenesis, substrate transport and hormone secretion, all of which influence fetal growth either via indirect effects on maternal substrate availability, or through direct effects on the placenta and its capacity to supply nutrients to the fetus. The extent to which IGFs influence the mother and/or placenta are dependent on the species and maternal factors, including age and nutrition. As altered fetal growth is associated with increased perinatal morbidity and mortality and a greater risk of developing degenerative diseases in adult life, understanding the role of maternal IGFs during pregnancy is essential in order to identify mechanisms underlying altered fetal growth and offspring programming. PMID:20921199

  2. An opioid growth factor regulates the replication of microorganisms.

    PubMed

    Zagon, I S; McLaughlin, P J

    1992-01-01

    An opioid growth factor (OGF), [Met5]-enkephalin, interacts with the zeta (zeta) opioid receptor to modulate development of eukaryotes. We have found that [Met5]-enkephalin, an endogenous opioid peptide serves to inhibit the growth of S. aureus. This effect on growth involves cell proliferative events and is under tonic control, since potent opioid antagonists accelerate cell replication. Both the OGF and zeta opioid receptor were associated with these microorganisms. Other opioid receptors (mu, delta and kappa) were not detected. OGF also controlled the growth of other bacteria: P. aeruginosa and S. marcesans. These results indicate that OGF and its receptor, known to be important in the regulation of mammalian development, also function in the growth of simple unicellular organisms. We suggest that the endogenous opioid system related to growth originated billions of years ago. PMID:1313136

  3. In Scarcity and Abundance: Metabolic Signals Regulating Cell Growth

    PubMed Central

    Saad, Shady; Peter, Matthias

    2013-01-01

    Although nutrient availability is a major driver of cell growth, and continuous adaptation to nutrient supply is critical for the development and survival of all organisms, the molecular mechanisms of nutrient sensing are only beginning to emerge. Here, we highlight recent advances in the field of nutrient sensing and discuss arising principles governing how metabolism might regulate growth-promoting pathways. In addition, we discuss signaling functions of metabolic enzymes not directly related to their metabolic activity. PMID:23997189

  4. Beclin 1 regulates growth factor receptor signaling in breast cancer.

    PubMed

    Rohatgi, R A; Janusis, J; Leonard, D; Bellvé, K D; Fogarty, K E; Baehrecke, E H; Corvera, S; Shaw, L M

    2015-10-16

    Beclin 1 is a haploinsufficient tumor suppressor that is decreased in many human tumors. The function of beclin 1 in cancer has been attributed primarily to its role in the degradative process of macroautophagy. However, beclin 1 is a core component of the vacuolar protein sorting 34 (Vps34)/class III phosphatidylinositoI-3 kinase (PI3KC3) and Vps15/p150 complex that regulates multiple membrane-trafficking events. In the current study, we describe an alternative mechanism of action for beclin 1 in breast cancer involving its control of growth factor receptor signaling. We identify a specific stage of early endosome maturation that is regulated by beclin 1, the transition of APPL1-containing phosphatidyIinositol 3-phosphate-negative (PI3P(-)) endosomes to PI3P(+) endosomes. Beclin 1 regulates PI3P production in response to growth factor stimulation to control the residency time of growth factor receptors in the PI3P(-)/APPL(+)-signaling-competent compartment. As a result, suppression of BECN1 sustains growth factor-stimulated AKT and ERK activation resulting in increased breast carcinoma cell invasion. In human breast tumors, beclin 1 expression is inversely correlated with AKT and ERK phosphorylation. Our data identify a novel role for beclin 1 in regulating growth factor signaling and reveal a mechanism by which loss of beclin 1 expression would enhance breast cancer progression. PMID:25639875

  5. Insulin signaling regulates neurite growth during metamorphic neuronal remodeling

    PubMed Central

    Gu, Tingting; Zhao, Tao; Hewes, Randall S.

    2014-01-01

    Summary Although the growth capacity of mature neurons is often limited, some neurons can shift through largely unknown mechanisms from stable maintenance growth to dynamic, organizational growth (e.g. to repair injury, or during development transitions). During insect metamorphosis, many terminally differentiated larval neurons undergo extensive remodeling, involving elimination of larval neurites and outgrowth and elaboration of adult-specific projections. Here, we show in the fruit fly, Drosophila melanogaster (Meigen), that a metamorphosis-specific increase in insulin signaling promotes neuronal growth and axon branching after prolonged stability during the larval stages. FOXO, a negative effector in the insulin signaling pathway, blocked metamorphic growth of peptidergic neurons that secrete the neuropeptides CCAP and bursicon. RNA interference and CCAP/bursicon cell-targeted expression of dominant-negative constructs for other components of the insulin signaling pathway (InR, Pi3K92E, Akt1, S6K) also partially suppressed the growth of the CCAP/bursicon neuron somata and neurite arbor. In contrast, expression of wild-type or constitutively active forms of InR, Pi3K92E, Akt1, Rheb, and TOR, as well as RNA interference for negative regulators of insulin signaling (PTEN, FOXO), stimulated overgrowth. Interestingly, InR displayed little effect on larval CCAP/bursicon neuron growth, in contrast to its strong effects during metamorphosis. Manipulations of insulin signaling in many other peptidergic neurons revealed generalized growth stimulation during metamorphosis, but not during larval development. These findings reveal a fundamental shift in growth control mechanisms when mature, differentiated neurons enter a new phase of organizational growth. Moreover, they highlight strong evolutionarily conservation of insulin signaling in neuronal growth regulation. PMID:24357229

  6. Substrate and nutrient limitation regulating microbial growth in soil

    NASA Astrophysics Data System (ADS)

    Bååth, Erland

    2015-04-01

    Microbial activity and growth in soil is regulated by several abiotic factors, including temperature, moisture and pH as the most important ones. At the same time nutrient conditions and substrate availability will also determine microbial growth. Amount of substrate will not only affect overall microbial growth, but also affect the balance of fungal and bacterial growth. The type of substrate will also affect the latter. Furthermore, according to Liebig law of limiting factors, we would expect one nutrient to be the main limiting one for microbial growth in soil. When this nutrient is added, the initial second liming factor will become the main one, adding complexity to the microbial response after adding different substrates. I will initially describe different ways of determining limiting factors for bacterial growth in soil, especially a rapid method estimating bacterial growth, using the leucine incorporation technique, after adding C (as glucose), N (as ammonium nitrate) and P (as phosphate). Scenarios of different limitations will be covered, with the bacterial growth response compared with fungal growth and total activity (respiration). The "degree of limitation", as well as the main limiting nutrient, can be altered by adding substrate of different stoichiometric composition. However, the organism group responding after alleviating the nutrient limitation can differ depending on the type of substrate added. There will also be situations, where fungi and bacteria appear to be limited by different nutrients. Finally, I will describe interactions between abiotic factors and the response of the soil microbiota to alleviation of limiting factors.

  7. N-cadherin regulates primary motor axon growth and branching during zebrafish embryonic development.

    PubMed

    Brusés, Juan L

    2011-06-15

    N-cadherin is a classical type I cadherin that contributes to the formation of neural circuits by regulating growth cone migration and the formation of synaptic contacts. This study analyzed the role of N-cadherin in primary motor axons growth during development of the zebrafish (Danio rerio) embryo. After exiting the spinal cord, primary motor axons migrate ventrally through a common pathway and form the first neuromuscular junction with the muscle pioneer cells located at the horizontal myoseptum, which serves as a choice point for cell-type-specific pathway selection. Analysis of N-cadherin mutants (cdh2(hi3644Tg) ) and embryos injected with N-cadherin antisense morpholinos showed primary motor axons extending aberrant axonal branches at the choice point in ∼40% of the somitic hemisegments and an ∼150% increase in the number of branches per axon length within the ventral myotome. Analysis of individual axons trajectories showed that the caudal (CaP) and rostral (RoP) motor neurons axons formed aberrant branches at the choice point that abnormally extended in the rostrocaudal axis and ventrally to the horizontal myoseptum. Expression of a dominant-interfering N-cadherin cytoplasmic domain in primary motor neurons caused some axons to stall abnormally at the horizontal myoseptum and to impair their migration into the ventral myotome. However, in N-cadherin-depleted embryos, the majority of primary motor axons innervated their appropriate myotomal territories, indicating that N-cadherin regulates motor axon growth and branching without severely affecting the mechanisms that control axonal target selection. PMID:21452216

  8. N-cadherin regulates primary motor axons growth and branching during zebrafish embryonic development

    PubMed Central

    Brusés, Juan L

    2013-01-01

    N-cadherin is a classical type I cadherin that contributes to the formation of neural circuits by regulating growth cone migration and the formation of synaptic contacts. This study analyzed the role of N-cadherin in primary motor axons growth during development of the zebrafish (Danio rerio) embryo. After exiting the spinal cord, primary motor axons migrate ventrally through a common pathway and form the first neuromuscular junction with the muscle pioneer cells located at the horizontal myoseptum, which serves as a choice point for cell-type specific pathway selection. Analysis of N-cadherin mutants (cdh2hi3644Tg) and embryos injected with N-cadherin antisense morpholinos showed primary motor axons extending aberrant axonal branches at the choice point in ~40% of the somitic hemisegments, and an ~150% increase in the number of branches per axon length within the ventral myotome. Analysis of individual axons trajectories showed that the caudal (CaP) and rostral (RoP) motor neurons axons formed aberrant branches at the choice point which abnormally extended in the rostrocaudal axis and ventrally to the horizontal myoseptum. Expression of a dominant-interfering N-cadherin cytoplasmic domain in primary motor neurons caused some axons to abnormally stall at the horizontal myoseptum and to impair their migration into the ventral myotome. However, in N-cadherin depleted embryos the majority of primary motor axons innervated their appropriate myotomal territories indicating that N-cadherin regulates motor axon growth and branching without severely affecting the mechanisms that control axonal target selection. PMID:21452216

  9. Cyp26b1 within the growth plate regulates bone growth in juvenile mice

    SciTech Connect

    Minegishi, Yoshiki; Sakai, Yasuo; Yahara, Yasuhito; Akiyama, Haruhiko; Yoshikawa, Hideki; Hosokawa, Ko; Tsumaki, Noriyuki

    2014-11-07

    Highlights: • Retinoic acid and Cyp26b1 were oppositely localized in growth plate cartilage. • Cyp26b1 deletion in chondrocytes decreased bone growth in juvenile mice. • Cyp26b1 deletion reduced chondrocyte proliferation and growth plate height. • Vitamin A-depletion partially reversed growth plate abnormalities caused by Cyp26b1 deficiency. • Cyp26b1 regulates bone growth by controlling chondrocyte proliferation. - Abstract: Retinoic acid (RA) is an active metabolite of vitamin A and plays important roles in embryonic development. CYP26 enzymes degrade RA and have specific expression patterns that produce a RA gradient, which regulates the patterning of various structures in the embryo. However, it has not been addressed whether a RA gradient also exists and functions in organs after birth. We found localized RA activities in the diaphyseal portion of the growth plate cartilage were associated with the specific expression of Cyp26b1 in the epiphyseal portion in juvenile mice. To disturb the distribution of RA, we generated mice lacking Cyp26b1 specifically in chondrocytes (Cyp26b1{sup Δchon} cKO). These mice showed reduced skeletal growth in the juvenile stage. Additionally, their growth plate cartilage showed decreased proliferation rates of proliferative chondrocytes, which was associated with a reduced height in the zone of proliferative chondrocytes, and closed focally by four weeks of age, while wild-type mouse growth plates never closed. Feeding the Cyp26b1 cKO mice a vitamin A-deficient diet partially reversed these abnormalities of the growth plate cartilage. These results collectively suggest that Cyp26b1 in the growth plate regulates the proliferation rates of chondrocytes and is responsible for the normal function of the growth plate and growing bones in juvenile mice, probably by limiting the RA distribution in the growth plate proliferating zone.

  10. New research with insect growth regulators and fogging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect growth regulators (IGRs) are seen as reduced-risk insecticides to replace conventional neurotoxins for insect pest management in stored products. The use of IGRs will be discussed, with reference to different application methods and available commercial products. Similarly, aerosol insecticid...

  11. Evaluation of Growth Regulators on In Vitro Hibiscus Shoot Regeneration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multiple shoot induction and plant regeneration was achieved from shoot apices in two genotypes (red and green variants) of Hibiscus acetosella Welw. ex. Hiern using the growth regulators thidiazuron (N-phenyl-N’-1,2,3-thidazol-5-ylurea, TDZ) and 6-benzyladenine (BA). Shoot apices were cultured for ...

  12. Heparin localization and fine structure regulate Burkitt's lymphoma growth

    SciTech Connect

    Berry, David; Lynn, David M.; Berry, Eric; Sasisekharan, Ram; Langer, Robert . E-mail: rlanger@mit.edu

    2006-09-29

    Burkitt's lymphoma (BL) is a B-cell malignancy associated with the Epstein-Barr virus (EBV). Mounting evidence has implicated heparan sulfate proteoglycans and heparan sulfate-like glycosaminoglycans (HSGAGs) in the initiation, severity, and progression of the malignancy. The importance of HSGAGs in regulating BL cell growth was therefore examined. Extracellular exogenous heparin inhibited cell growth >30%, while heparin internalized with poly({beta}-amino ester)s promoted proliferation up to 58%. The growth-modulating effects of heparin and internalized heparin were dependent on cell surface HSGAGs, PI3K, and Erk/Mek. Treatment of cells with protamine sulfate or with heparinases potently inhibited proliferation, with the greatest effects induced by heparinase I. Cell surface HSGAGs therefore play an important role in regulating BL proliferation and may offer a potential target for therapeutic intervention.

  13. Maternal effects and the endocrine regulation of mandrill growth.

    PubMed

    Bernstein, Robin M; Setchell, Joanna M; Verrier, Delphine; Knapp, Leslie A

    2012-10-01

    Maternal effects can influence offspring growth and development, and thus fitness. However, the physiological factors mediating these effects in nonhuman primates are not well understood. We investigated the impact of maternal effects on variation in three important components of the endocrine regulation of growth in male and female mandrills (Mandrillus sphinx), from birth to 9 years of age. Using a mixed longitudinal set (N = 252) of plasma samples, we measured concentrations of insulin-like growth factor-I (IGF-I), growth hormone binding protein (GHBP), and free testosterone (free T). We evaluated the relationship of ontogenetic patterns of changes in hormone concentration to patterns of growth in body mass and body length, and determined that these endocrine factors play a significant role in growth of both young (infant and juvenile) and adolescent male mandrills, but only in growth of young female mandrills. We also use mixed models analysis to determine the relative contribution of the effects of maternal rank, parity, and age on variation in hormone and binding protein concentrations. Our results suggest that all of these maternal effects account for significant variation in hormone and binding protein concentrations in all male age groups. Of the maternal effects measured, maternal rank was the most frequently identified significant maternal effect on variation in hormone and binding protein concentrations. We suggest that these endocrine factors provide mechanisms that contribute to the maternal effects on offspring growth previously noted in this population. PMID:22696170

  14. Redox regulation in shoot growth, SAM maintenance and flowering.

    PubMed

    Schippers, Jos Hm; Foyer, Christine H; van Dongen, Joost T

    2016-02-01

    Reactive oxygen species (ROS) and associated reduction/oxidation (redox) controls involving glutathione, glutaredoxins and thioredoxins play key roles in the regulation of plant growth and development. While many questions remain concerning redox functions in the shoot apical meristem (SAM), accumulating evidence suggests that redox master switches integrate major hormone signals and transcriptional networks in the SAM, and so regulate organ growth, polarity and floral development. Auxin-induced activation of plasma-membrane located NADPH-oxidases and mitochondrial respiratory bioenergetics are likely regulators of the ROS bursts that drive the cell cycle in proliferating regions, with other hormones such as jasmonic acid playing propagating or antagonistic roles in gene regulation. Moreover, the activation of oxygen production by photosynthesis and oxygen-dependent N-end rule controls are linked to the transition from cell proliferation to cell expansion and differentiation. While much remains to be understood, the nexus of available redox controls provides a key underpinning mechanism linking hormonal controls, energy metabolism and bioenergetics to plant growth and development. PMID:26799134

  15. Redox-dependent regulation of epidermal growth factor receptor signaling.

    PubMed

    Heppner, David E; van der Vliet, Albert

    2016-08-01

    Tyrosine phosphorylation-dependent cell signaling represents a unique feature of multicellular organisms, and is important in regulation of cell differentiation and specialized cell functions. Multicellular organisms also contain a diverse family of NADPH oxidases (NOXs) that have been closely linked with tyrosine kinase-based cell signaling and regulate tyrosine phosphorylation via reversible oxidation of cysteine residues that are highly conserved within many proteins involved in this signaling pathway. An example of redox-regulated tyrosine kinase signaling involves the epidermal growth factor receptor (EGFR), a widely studied receptor system with diverse functions in normal cell biology as well as pathologies associated with oxidative stress such as cancer. The purpose of this Graphical Redox Review is to highlight recently emerged concepts with respect to NOX-dependent regulation of this important signaling pathway. PMID:26722841

  16. Redox-dependent regulation of epidermal growth factor receptor signaling

    PubMed Central

    Heppner, David E.; van der Vliet, Albert

    2015-01-01

    Tyrosine phosphorylation-dependent cell signaling represents a unique feature of multicellular organisms, and is important in regulation of cell differentiation and specialized cell functions. Multicellular organisms also contain a diverse family of NADPH oxidases (NOXs) that have been closely linked with tyrosine kinase-based cell signaling and regulate tyrosine phosphorylation via reversible oxidation of cysteine residues that are highly conserved within many proteins involved in this signaling pathway. An example of redox-regulated tyrosine kinase signaling involves the epidermal growth factor receptor (EGFR), a widely studied receptor system with diverse functions in normal cell biology as well as pathologies associated with oxidative stress such as cancer. The purpose of this Graphical Redox Review is to highlight recently emerged concepts with respect to NOX-dependent regulation of this important signaling pathway. PMID:26722841

  17. Regulation of Growth Hormone by the Splanchnic Area.

    PubMed

    Barja-Fernandez, Silvia; Folgueira, Cintia; Castelao, Cecilia; Leis, Rosaura; Crujeiras, Ana B; Casanueva, Felipe F; Seoane, Luisa M

    2016-01-01

    The regulation of growth hormone (GH) was traditionally thought to be under the control of two main hypothalamic neuropeptides; GH-releasing hormone and somatostatin. In 1999, with the isolation of ghrelin, as a gastric-derived peptide with potent GH-releasing activity, concept of regulation of the somatotropic axis completely changed. In addition to its GH-releasing activity, ghrelin exhibited the capacity to modulate food intake and body weight. The role of this splanchnic factor in regulating GH as a nexus of energy balance control and GH are explored in this chapter. From a physiological standpoint, a novel mechanism of GH regulation mediated by ghrelin exists, implicating the peripheral modulation of the cannabinoid receptor. PMID:26940386

  18. Mechanical stress regulation of plant growth and development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Myers, P. N.

    1995-01-01

    The authors introduce the chapter with a discussion of lessons from nature, agriculture, and landscapes; terms and definitions; and an historical perspective of mechanical stress regulation of plant growth and development. Topics include developmental responses to mechanical stress; mechanical stress-environment interactions; metabolic, productivity, and compositional changes; hormonal involvement; mechanoperception and early transduction mechanisms; applications in agriculture; and research implications. The discussion of hormonal involvement in mechanical stress physiology includes ethylene, auxin, gibberellins, and other phytohormones. The discussion of applications in agriculture examines windbreaks, nursery practices, height control and conditioning, and enhancement of growth and productivity. Implications for research are related to handling plant materials, space biology, and future research needs.

  19. Growth-regulated synthesis and secretion of biologically active nerve growth factor by human keratinocytes.

    PubMed

    Di Marco, E; Marchisio, P C; Bondanza, S; Franzi, A T; Cancedda, R; De Luca, M

    1991-11-15

    Nerve growth factor (NGF) transcripts were identified in normal human keratinocytes in primary and secondary culture. The expression of the NGF mRNA was strongly down-regulated by corticosteroids and was maximal when keratinocytes were in the exponential phase of growth. Immunofluorescence studies on growing keratinocytes colonies and on elutriated keratinocytes obtained from growing colonies and mature stratified epithelium showed specific staining of the Golgi apparatus only in basal keratinocytes in the exponential phase of growth. The keratinocyte-derived NGF was secreted in a biologically active form as assessed by neurite induction in sensory neurons obtained from chick embryo dorsal root ganglia. Based on these data we suggest that the basal keratinocyte is the cell synthesizing and secreting NGF in the human adult epidermis. The paracrine secretion of NGF by keratinocytes might have a major role in regulating innervation, lymphocyte function, and melanocyte growth and differentiation in epidermal morphogenesis as well as during wound healing. PMID:1718982

  20. Light-Mediated Hormonal Regulation of Plant Growth and Development.

    PubMed

    de Wit, Mieke; Galvão, Vinicius Costa; Fankhauser, Christian

    2016-04-29

    Light is crucial for plant life, and perception of the light environment dictates plant growth, morphology, and developmental changes. Such adjustments in growth and development in response to light conditions are often established through changes in hormone levels and signaling. This review discusses examples of light-regulated processes throughout a plant's life cycle for which it is known how light signals lead to hormonal regulation. Light acts as an important developmental switch in germination, photomorphogenesis, and transition to flowering, and light cues are essential to ensure light capture through architectural changes during phototropism and the shade avoidance response. In describing well-established links between light perception and hormonal changes, we aim to give insight into the mechanisms that enable plants to thrive in variable light environments. PMID:26905653

  1. Chloride binding regulates the Schiff base pK in gecko P521 cone-type visual pigment.

    PubMed

    Yuan, C; Kuwata, O; Liang, J; Misra, S; Balashov, S P; Ebrey, T G

    1999-04-01

    The binding of chloride is known to shift the absorption spectrum of most long-wavelength-absorbing cone-type visual pigments roughly 30 nm to the red. We determined that the chloride binding constant for this color shift in the gecko P521 visual pigment is 0.4 mM at pH 6.0. We found an additional effect of chloride on the P521 pigment: the apparent pKa of the Schiff base in P521 is greatly increased as the chloride concentration is increased. The apparent Schiff base pKa shifts from 8.4 for the chloride-free form to >10.4 for the chloride-bound form. We show that this shift is due to chloride binding to the pigment, not to the screening of the membrane surface charges by chloride ions. We also found that at high pH, the absorption maximum of the chloride-free pigment shifts from 495 to 475 nm. We suggest that the chloride-dependent shift of the apparent Schiff base pKa is due to the deprotonation of a residue in the chloride binding site with a pKa of ca. 8.5, roughly that of the Schiff base in the absence of chloride. The deprotonation of this site results in the formation of the 475 nm pigment and a 100-fold decrease in the pigment's ability to bind chloride. Increasing the concentration of chloride results in the stabilization of the protonated state of this residue in the chloride binding site and thus increased chloride binding with an accompanying increase in the Schiff base pK. PMID:10194387

  2. Aromatic fluorine compounds. VIII. Plant growth regulators and intermediates

    USGS Publications Warehouse

    Finger, G.C.; Gortatowski, M.J.; Shiley, R.H.; White, R.H.

    1959-01-01

    The preparation and properties of 41 fluorophenoxyacetic acids, 4 fluorophenoxypropionic acids, 2 fluorobenzoic acids, several indole derivatives, and a number of miscellaneous compounds are described. Data are given for many intermediates such as new fluorinated phenols, anisoles, anilines and nitrobenzenes. Most of the subject compounds are related to a number of well-known herbicides or plant growth regulators such as 2,4-D, 2,4,5-T and others.

  3. Regulation of wound healing by growth factors and cytokines.

    PubMed

    Werner, Sabine; Grose, Richard

    2003-07-01

    Cutaneous wound healing is a complex process involving blood clotting, inflammation, new tissue formation, and finally tissue remodeling. It is well described at the histological level, but the genes that regulate skin repair have only partially been identified. Many experimental and clinical studies have demonstrated varied, but in most cases beneficial, effects of exogenous growth factors on the healing process. However, the roles played by endogenous growth factors have remained largely unclear. Initial approaches at addressing this question focused on the expression analysis of various growth factors, cytokines, and their receptors in different wound models, with first functional data being obtained by applying neutralizing antibodies to wounds. During the past few years, the availability of genetically modified mice has allowed elucidation of the function of various genes in the healing process, and these studies have shed light onto the role of growth factors, cytokines, and their downstream effectors in wound repair. This review summarizes the results of expression studies that have been performed in rodents, pigs, and humans to localize growth factors and their receptors in skin wounds. Most importantly, we also report on genetic studies addressing the functions of endogenous growth factors in the wound repair process. PMID:12843410

  4. LAT1 regulates growth of uterine leiomyoma smooth muscle cells.

    PubMed

    Xia Luo; Coon, John S; Su, Emily; Pearson, Elizabeth Kerry; Ping Yin; Ishikawa, Hiroshi; Bulun, Serdar E

    2010-09-01

    L-type amino acid transporter 1 (LAT1) and LAT2 were shown to encode system L, which mediates the Na(+)-independent transport of branched-chain and aromatic amino acids. We demonstrated previously that LAT2 is a progesterone receptor target gene involved in leiomyoma growth. The role of LAT1 in the regulation of human uterine leiomyoma growth, however, remains unelucidated. We herein investigated the function of LAT1 and its progesterone-mediated regulation within human uterine leiomyoma smooth muscle (LSM) cells (n = 8) and tissues (n = 29). In vivo, LAT1 expression was higher in leiomyoma than in myometrial tissue. LAT1 knockdown augmented cell proliferation and viability. Treatment of LSM cells with RU486 markedly increased LAT1 messenger RNA (mRNA) levels but decreased proliferation in a dose-dependent manner. L-type amino acid transporter 1 as a downstream target, however, did not entirely account for this antiproliferative effect of RU486 on LSM cells. Taken together, LAT1 may have a critical and complex role in regulating human leiomyoma cell growth. PMID:20601542

  5. RNAi screens in mice identify physiological regulators of oncogenic growth

    PubMed Central

    Beronja, Slobodan; Janki, Peter; Heller, Evan; Lien, Wen-Hui; Keyes, Brice; Oshimori, Naoki; Fuchs, Elaine

    2013-01-01

    Summary Tissue growth is the multifaceted outcome of a cell’s intrinsic capabilities and its interactions with the surrounding environment. Decoding these complexities is essential for understanding human development and tumorigenesis. Here, we tackle this problem by carrying out the first genome-wide RNAi-mediated screens in mice. Focusing on skin development and oncogenic (HrasG12V-induced) hyperplasia, our screens uncover novel as well as anticipated regulators of embryonic epidermal growth. Among top oncogenic screen hits are Mllt6 and the Wnt effector β-catenin; they maintain HrasG12V-dependent hyperproliferation. We also expose β-catenin as an unanticipated antagonist of normal epidermal growth, functioning through Wnt-independent intercellular adhesion. Finally, we document physiological relevance to mouse and human cancers, thereby establishing the feasibility of in vivo mammalian genome-wide investigations to dissect tissue development and tumorigenesis. By documenting some oncogenic growth regulators, we pave the way for future investigations of other hits and raise promise for unearthing new targets for cancer therapies. PMID:23945586

  6. ROS Regulation of Polar Growth in Plant Cells.

    PubMed

    Mangano, Silvina; Juárez, Silvina Paola Denita; Estevez, José M

    2016-07-01

    Root hair cells and pollen tubes, like fungal hyphae, possess a typical tip or polar cell expansion with growth limited to the apical dome. Cell expansion needs to be carefully regulated to produce a correct shape and size. Polar cell growth is sustained by oscillatory feedback loops comprising three main components that together play an important role regulating this process. One of the main components are reactive oxygen species (ROS) that, together with calcium ions (Ca(2+)) and pH, sustain polar growth over time. Apoplastic ROS homeostasis controlled by NADPH oxidases as well as by secreted type III peroxidases has a great impact on cell wall properties during cell expansion. Polar growth needs to balance a focused secretion of new materials in an extending but still rigid cell wall in order to contain turgor pressure. In this review, we discuss the gaps in our understanding of how ROS impact on the oscillatory Ca(2+) and pH signatures that, coordinately, allow root hair cells and pollen tubes to expand in a controlled manner to several hundred times their original size toward specific signals. PMID:27208283

  7. ROS Regulation of Polar Growth in Plant Cells1[OPEN

    PubMed Central

    Mangano, Silvina; Juárez, Silvina Paola Denita

    2016-01-01

    Root hair cells and pollen tubes, like fungal hyphae, possess a typical tip or polar cell expansion with growth limited to the apical dome. Cell expansion needs to be carefully regulated to produce a correct shape and size. Polar cell growth is sustained by oscillatory feedback loops comprising three main components that together play an important role regulating this process. One of the main components are reactive oxygen species (ROS) that, together with calcium ions (Ca2+) and pH, sustain polar growth over time. Apoplastic ROS homeostasis controlled by NADPH oxidases as well as by secreted type III peroxidases has a great impact on cell wall properties during cell expansion. Polar growth needs to balance a focused secretion of new materials in an extending but still rigid cell wall in order to contain turgor pressure. In this review, we discuss the gaps in our understanding of how ROS impact on the oscillatory Ca2+ and pH signatures that, coordinately, allow root hair cells and pollen tubes to expand in a controlled manner to several hundred times their original size toward specific signals. PMID:27208283

  8. Whiskers, cones and pyramids created in sputtering by ion bombardment

    NASA Technical Reports Server (NTRS)

    Wehner, G. K.

    1979-01-01

    A thorough study of the role which foreign atoms play in cone formation during sputtering of metals revealed many experimental facts. Two types of cone formation were distinquished, deposit cones and seed cones. Twenty-six combinations of metals for seed cone formation were tested. The sputtering yield variations with composition for combinations which form seed cones were measured. It was demonstrated that whisker growth becomes a common occurrence when low melting point material is sputter deposited on a hot nonsputtered high melting point electrode.

  9. Influence of growth regulators on plant growth, yield, and skin color of specialty potatoes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    2,4-D has been used since the 1950’s to enhance color in red-skinned potatoes, but there is little research on the potential use of other plant growth regulators to improve tuber skin color in the wide range of specialty potatoes now available on the market. Field trials conducted at Parma, ID in 20...

  10. HMGCR positively regulated the growth and migration of glioblastoma cells.

    PubMed

    Qiu, Zhihua; Yuan, Wen; Chen, Tao; Zhou, Chenzhi; Liu, Chao; Huang, Yongkai; Han, Deqing; Huang, Qinghui

    2016-01-15

    The metabolic program of cancer cells is significant different from the normal cells, which makes it possible to develop novel strategies targeting cancer cells. Mevalonate pathway and its rate-limiting enzyme HMG-CoA reductase (HMGCR) have shown important roles in the progression of several cancer types. However, their roles in glioblastoma cells remain unknown. In this study, up-regulation of HMGCR in the clinical glioblastoma samples was observed. Forced expression of HMGCR promoted the growth and migration of U251 and U373 cells, while knocking down the expression of HMGCR inhibited the growth, migration and metastasis of glioblastoma cells. Molecular mechanism studies revealed that HMGCR positively regulated the expression of TAZ, an important mediator of Hippo pathway, and the downstream target gene connective tissue growth factor (CTGF), suggesting HMGCR might activate Hippo pathway in glioblastoma cells. Taken together, our study demonstrated the oncogenic roles of HMGCR in glioblastoma cells and HMGCR might be a promising therapeutic target. PMID:26432005

  11. Hedgehog signaling in prostate epithelial-mesenchymal growth regulation

    PubMed Central

    Peng, Yu-Ching; Joyner, Alexandra L.

    2015-01-01

    The prostate gland plays an important role in male reproduction, and is also an organ prone to diseases such as benign prostatic hyperplasia (BPH) and prostate cancer. The prostate consists of ducts with an inner layer of epithelium surrounded by stroma. Reciprocal signaling between these two cell compartments is instrumental to normal prostatic development, homeostasis, regeneration, as well as tumor formation. Hedgehog (HH) signaling is a master regulator in numerous developmental processes. In many organs, HH plays a key role in epithelial-mesenchymal signaling that regulates organ growth and tissue differentiation, and abnormal HH signaling has been implicated in the progression of various epithelial carcinomas. In this review, we focus on recent studies exploring the multipotency of endogenous postnatal and adult epithelial and stromal stem cells and studies addressing the role of HH in prostate development and cancer. We discuss the implications of the results for a new understanding of prostate development and disease. Insight into the cellular and molecular mechanisms underlying epithelial-mesenchymal growth regulation should provide a basis for devising innovative therapies to combat diseases of the prostate. PMID:25641695

  12. Nitrate-Regulated Glutaredoxins Control Arabidopsis Primary Root Growth.

    PubMed

    Patterson, Kurt; Walters, Laura A; Cooper, Andrew M; Olvera, Jocelyn G; Rosas, Miguel A; Rasmusson, Allan G; Escobar, Matthew A

    2016-02-01

    Nitrogen is an essential soil nutrient for plants, and lack of nitrogen commonly limits plant growth. Soil nitrogen is typically available to plants in two inorganic forms: nitrate and ammonium. To better understand how nitrate and ammonium differentially affect plant metabolism and development, we performed transcriptional profiling of the shoots of ammonium-supplied and nitrate-supplied Arabidopsis (Arabidopsis thaliana) plants. Seven genes encoding class III glutaredoxins were found to be strongly and specifically induced by nitrate. RNA silencing of four of these glutaredoxin genes (AtGRXS3/4/5/8) resulted in plants with increased primary root length (approximately 25% longer than the wild type) and decreased sensitivity to nitrate-mediated inhibition of primary root growth. Increased primary root growth is also a well-characterized phenotype of many cytokinin-deficient plant lines. We determined that nitrate induction of glutaredoxin gene expression was dependent upon cytokinin signaling and that cytokinins could activate glutaredoxin gene expression independent of plant nitrate status. In addition, crosses between "long-root" cytokinin-deficient plants and "long-root" glutaredoxin-silenced plants generated hybrids that displayed no further increase in primary root length (i.e. epistasis). Collectively, these findings suggest that AtGRXS3/4/5/8 operate downstream of cytokinins in a signal transduction pathway that negatively regulates plant primary root growth in response to nitrate. This pathway could allow Arabidopsis to actively discriminate between different nitrogen sources in the soil, with the preferred nitrogen source, nitrate, acting to suppress primary root growth (vertical dimension) in concert with its well-characterized stimulatory effect on lateral root growth (horizontal dimension). PMID:26662603

  13. Host metabolism regulates intracellular growth of Trypanosoma cruzi.

    PubMed

    Caradonna, Kacey L; Engel, Juan C; Jacobi, David; Lee, Chih-Hao; Burleigh, Barbara A

    2013-01-16

    Metabolic coupling of intracellular pathogens with host cells is essential for successful colonization of the host. Establishment of intracellular infection by the protozoan Trypanosoma cruzi leads to the development of human Chagas' disease, yet the functional contributions of the host cell toward the infection process remain poorly characterized. Here, a genome-scale functional screen identified interconnected metabolic networks centered around host energy production, nucleotide metabolism, pteridine biosynthesis, and fatty acid oxidation as key processes that fuel intracellular T. cruzi growth. Additionally, the host kinase Akt, which plays essential roles in various cellular processes, was critical for parasite replication. Targeted perturbations in these host metabolic pathways or Akt-dependent signaling pathways modulated the parasite's replicative capacity, highlighting the adaptability of this intracellular pathogen to changing conditions in the host. These findings identify key cellular process regulating intracellular T. cruzi growth and illuminate the potential to leverage host pathways to limit T. cruzi infection. PMID:23332160

  14. Host metabolism regulates intracellular growth of Trypanosoma cruzi

    PubMed Central

    Caradonna, Kacey L.; Engel, Juan C.; Jacobi, David; Lee, Chih-Hao; Burleigh, Barbara A.

    2012-01-01

    SUMMARY Metabolic coupling of intracellular pathogens with host cells is essential for successful colonization of the host. Establishment of intracellular infection by the protozoan Trypanosoma cruzi leads to the development of human Chagas disease, yet the functional contributions of the host cell toward the infection process remain poorly characterized. Here, a genome-scale functional screen identified interconnected metabolic networks centered around host energy production, nucleotide metabolism, pteridine biosynthesis, and fatty acid oxidation as key processes that fuel intracellular T. cruzi growth. Additionally, the host kinase Akt, which plays essential roles in various cellular processes, was critical for parasite replication. Targeted perturbations in these host metabolic pathways or Akt-dependent signaling pathways modulated the parasite’s replicative capacity, highlighting the adaptability of this intracellular pathogen to changing conditions in the host. These findings identify key cellular process regulating intracellular T. cruzi growth and illuminate the potential to leverage host pathways to limit T. cruzi infection. PMID:23332160

  15. Defining human insulin-like growth factor I gene regulation.

    PubMed

    Mukherjee, Aditi; Alzhanov, Damir; Rotwein, Peter

    2016-08-01

    Growth hormone (GH) plays an essential role in controlling somatic growth and in regulating multiple physiological processes in humans and other species. Insulin-like growth factor I (IGF-I), a conserved, secreted 70-amino acid peptide, is a critical mediator of many of the biological effects of GH. Previous studies have demonstrated that GH rapidly and potently promotes IGF-I gene expression in rodents and in some other mammals through the transcription factor STAT5b, leading to accumulation of IGF-I mRNAs and production of IGF-I. Despite this progress, very little is known about how GH or other trophic factors control human IGF1 gene expression, in large part because of the absence of any cellular model systems that robustly express IGF-I. Here, we have addressed mechanisms of regulation of human IGF-I by GH after generating cells in which the IGF1 chromosomal locus has been incorporated into a mouse cell line. Using this model, we found that physiological levels of GH rapidly stimulate human IGF1 gene transcription and identify several potential transcriptional enhancers in chromatin that bind STAT5b in a GH-regulated way. Each of the putative enhancers also activates a human IGF1 gene promoter in reconstitution experiments in the presence of the GH receptor, STAT5b, and GH. Thus we have developed a novel experimental platform that now may be used to determine how human IGF1 gene expression is controlled under different physiological and pathological conditions. PMID:27406741

  16. Paleomagnetic, Anisortopy of Magnetic Susceptibility, and structural Data Bearing on Magma Emplacement and the growth of the Miocene Hrad Trosky a Monogenic Strombolian Cinder Cone

    NASA Astrophysics Data System (ADS)

    Brister, A. R.; Petronis, M. S.; Lindline, J.; Van Wyk de Vries, B.; Rapprich, V.

    2012-12-01

    The Hrad (castle) Trosky is a 14th century medieval castle located in NE Bohemia, Czech Republic built on top of a monogenic Strombolian cinder-spatter cone. The Hrad Trosky Volcano belongs to a relatively well-preserved set of middle Miocene scoria cones in the Jičín Volcanic field. Volcanic activity occurred in the form of scattered Strombolian eruptions from multiple volcanic centers producing basanitic magmas mostly erupted along an east-west trend associated with the Lusatian fault. Erosion of the Hrad Trosky Volcano resulted in exceptional three dimensional exposure of the magma feeder conduit system. In order to gain a better understanding of the magma emplacement and subvolcanic deformation processes at the Hrad Trosky volcano we collected samples for a detailed, paleomagnetic, anisotropy of magnetic susceptibility (AMS), and structural study. AMS data provides information on magma flow patterns and improve our understanding of the kinematics of magma flow. Paleomagnetic data will be compared to the late Miocene expected field direction to discern any subvocanic deformation associated with subsequent intrusions during the growth of the volcanic system. Structural data, such as basic field mapping, fracture patterns, Reidel shears, and other kinematic indicator, should provide additional constraints on the details of volcanic construction and/or deformation. To asses the evolution of the Hrad Trosky volcano, we collected twenty-one sampling sites with eight to fourteen sample collected at each sites. These include fifteen sites in the magma conduit, five sites in lava flows, and one site scoria. In addition, we conducted five baked-contact tests to evaluate the stability of the remanence and the antiquity of the magnetization. Preliminary results are encouraging with AMS data yielding high susceptibility resultsand well defined principal susceptibility axes. Paleomagnetic data show a relatively simple demagnetization behavior that likely reflects a primary

  17. MEPE is a novel regulator of growth plate cartilage mineralization

    PubMed Central

    Staines, K.A.; Mackenzie, N.C.W.; Clarkin, C.E.; Zelenchuk, L.; Rowe, P.S.; MacRae, V.E.; Farquharson, C.

    2012-01-01

    Matrix extracellular phosphoglycoprotein (MEPE) belongs to the SIBLING protein family which play key roles in biomineralization. Although the growth plates of MEPE-overexpressing mice display severe morphological disruption, the expression and function of MEPE in growth plate matrix mineralization remains largely undefined. Here we show MEPE and its cleavage product, the acidic serine aspartate-rich MEPE-associated motif (ASARM) peptide, to be localised to the hypertrophic zone of the growth plate. We also demonstrate that the phosphorylated (p)ASARM peptide inhibits ATDC5 chondrocyte matrix mineralization. Stable MEPE-overexpressing ATDC5 cells also had significantly reduced matrix mineralization in comparison to the control cells. Interestingly, we show that the addition of the non-phosphorylated (np)ASARM peptide promoted mineralization in the ATDC5 cells. The peptides and the overexpression of MEPE did not affect the differentiation of the ATDC5 cells. For a more physiologically relevant model, we utilized the metatarsal organ culture model. We show the pASARM peptide to inhibit mineralization at two stages of development, as shown by histological and μCT analysis. Like in the ATDC5 cells, the peptides did not affect the differentiation of the metatarsals indicating that the effects seen on mineralization are direct, as is additionally confirmed by no change in alkaline phosphatase activity or mRNA expression. In the metatarsal organ cultures, the pASARM peptide also reduced endothelial cell markers and vascular endothelial growth factor mRNA expression. Taken together these results show MEPE to be an important regulator of growth plate chondrocyte matrix mineralization through its cleavage to an ASARM peptide. PMID:22766095

  18. Economic growth and energy regulation in the environmental Kuznets curve.

    PubMed

    Lorente, Daniel Balsalobre; Álvarez-Herranz, Agustín

    2016-08-01

    This study establishes the existence of a pattern of behavior, between economic growth and environmental degradation, consistent with the environmental Kuznets curve (EKC) hypothesis for 17 Organization for Economic Cooperation and Development (OECD) countries between 1990 and 2012. Based on this EKC pattern, it shows that energy regulation measures help reduce per capita greenhouse gas (GHG) emissions. To validate this hypothesis, we also add the explanatory variables: renewable energy promotion, energy innovation processes, and the suppression effect of income level on the contribution of renewable energy sources to total energy consumption. It aims to be a tool for decision-making regarding energy policy. This paper provides a two-stage econometric analysis of instrumental variables with the aim of correcting the existence of endogeneity in the variable GDP per capita, verifying that the instrumental variables used in this research are appropriate for our aim. To this end, it first makes a methodological contribution before incorporating additional variables associated with environmental air pollution into the EKC hypothesis and showing how they positively affect the explanation of the correction in the GHG emission levels. This study concludes that air pollution will not disappear on its own as economic growth increases. Therefore, it is necessary to promote energy regulation measures to reduce environmental pollution. PMID:27164892

  19. Genetic analysis of growth-regulator-induced parthenocarpy in Arabidopsis.

    PubMed

    Vivian-Smith, A; Koltunow, A M

    1999-10-01

    In Arabidopsis, seedless silique development or parthenocarpy can be induced by the application of various plant growth regulators (PGRs) to unfertilized pistils. Ecotype-specific responses were observed in the Arabidopsis ecotypes Columbia and Landsberg relative to the type of PGR and level applied. The parthenocarpic response was greatest in ecotype Landsberg, and comparisons of fruit growth and morphology were studied primarily in this ecotype. Gibberellic acid application (10 micromol pistil(-1)) caused development similar to that in pollinated pistils, while benzyladenine (1 micromol pistil(-1)) and naphthylacetic acid (10 micromol pistil(-1)) treatment produced shorter siliques. Naphthylacetic acid primarily modified mesocarp cell expansion. Arabidopsis mutants were employed to examine potential dependencies on gibberellin biosynthesis (ga1-3, ga4-1, and ga5-1) and perception (spy-4 and gai) during parthenocarpic silique development. Emasculated spy-4 pistils were neither obviously parthenocarpic nor deficient in PGR perception. By contrast, emasculated gai mutants did not produce parthenocarpic siliques following gibberellic acid application, but silique development occurred following pollination or application of auxin and cytokinin. Pollinated gai siliques had decreased cell numbers and morphologically resembled auxin-induced parthenocarpic siliques. This shows that a number of independent and possibly redundant pathways can direct hormone-induced parthenocarpy, and that endogenous gibberellins play a role in regulating cell expansion and promoting cell division in carpels. PMID:10517835

  20. Erdr1 Suppresses Murine Melanoma Growth via Regulation of Apoptosis

    PubMed Central

    Lee, Joohyun; Jung, Min Kyung; Park, Hyun Jeong; Kim, Kyung Eun; Cho, Daeho

    2016-01-01

    Melanoma, one of the aggressive cancers, is known to be resistant to chemotherapy. Because of its aggressive nature, effectively inducing apoptosis is necessary to treat melanoma. Erythroid differentiation regulator 1 (Erdr1) is known to be a stress-related survival factor exhibiting anti-cancer effects in several cancers. However, little is known about the functions and underlying mechanisms of Erdr1 so far. To demonstrate the effect of Erdr1 in melanoma apoptosis, recombinant murine Erdr1 was injected into mice implanted with B16F10 melanoma cells. In vivo tumor growth was significantly inhibited in mice injected with Erdr1 compared to the control. In addition, the tumor from Erdr1-injected mice showed an increased level of apoptosis. Accordingly, apoptosis-regulating factors including anti-apoptotic marker Bcl-2 and pro-apoptotic marker Bax in the tumor tissues were examined. As expected, the decreased level of Bcl-2 and increased level of Bax were detected in tumors within the mice injected with Erdr1. Based on the in vivo study, the role of Erdr1 in tumor apoptosis was further tested by incubating it with cells of the murine melanoma cell line B16F10. Erdr1-induced apoptosis in B16F10 cells was observed. Additionally, Erdr1 downregulated STAT3 activity, inhibiting apoptosis via regulation of the Bcl-2 family. Overall, data demonstrate that Erdr1 induced murine melanoma apoptosis through the regulation of Bcl-2 and Bax. These findings suggest that Erdr1 is a novel regulator of apoptosis in melanoma. PMID:26784177

  1. Sulf1A and HGF regulate satellite-cell growth

    PubMed Central

    Gill, Roop; Hitchins, Laura; Fletcher, Fenella; Dhoot, Gurtej K.

    2010-01-01

    The role of Sulf1A, sulfation and hepatocyte growth factor (HGF) in satellite-cell growth was examined in an in vitro model of dissociated whole skeletal muscle fibres. Pax7-positive quiescent satellite cells express little or no Sulf1A but show rapid re-expression in regenerating myoblasts and myotubes, similar to embryonic muscle and in vitro satellite cells preceding asynchronous MyoD activation. Once activated, Sulf1A and MyoD re-expression persists up to 72 hours in most satellite cells under normal culture conditions and following moderate changes in sulfation, whereas Sulf1A neutralisation by antibodies not only enhances satellite-cell proliferation but also downregulates MyoD and Pax7 expression in a large proportion of the satellite cells. The HGF exposure also induces similar but even more pronounced changes characterised by variable sulfation levels and rapid downregulation of MyoD and Pax7 without myogenin activation in a sub-set of cells. This Pax7-MyoD-myogenin-negative sub-population expresses Sulf1A and Myf5. The transfer of all such satellite-cell progenies onto gelatin-coated-substratum re-activates MyoD and Pax7 gene expression in all cells, thus detecting a distinct sub-population of satellite cells. We conclude that HGF and fine-tuned sulfation levels are major contributory factors controlling satellite-cell growth by regulating the relative activities of actively proliferating and differentiating cells. PMID:20442248

  2. ARNT2 Regulates Tumoral Growth in Oral Squamous Cell Carcinoma

    PubMed Central

    Kimura, Yasushi; Kasamatsu, Atsushi; Nakashima, Dai; Yamatoji, Masanobu; Minakawa, Yasuyuki; Koike, Kazuyuki; Fushimi, Kazuaki; Higo, Morihiro; Endo-Sakamoto, Yosuke; Shiiba, Masashi; Tanzawa, Hideki; Uzawa, Katsuhiro

    2016-01-01

    Aryl hydrocarbon receptor nuclear translocator (ARNT) 2 is a transcriptional factor related to adaptive responses against cellular stress from a xenobiotic substance. Recent evidence indicates ARNT is involved in carcinogenesis and cancer progression; however, little is known about the relevance of ARNT2 in the behavior of oral squamous cell carcinoma (OSCC). In the current study, we evaluated the ARNT2 mRNA and protein expression levels in OSCC in vitro and in vivo and the clinical relationship between ARNT2 expression levels in primary OSCCs and their clinicopathologic status by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and immunohistochemistry. Using ARNT2 overexpression models, we performed functional analyses to investigate the critical roles of ARNT2 in OSCC. ARNT2 mRNA and protein were down-regulated significantly (P < 0.05 for both comparisons) in nine OSCC-derived cells and primary OSCC (n=100 patients) compared with normal counterparts. In addition to the data from exogenous experiments that ARNT2-overexpressed cells showed decreased cellular proliferation, ARNT2-positive OSCC cases were correlated significantly (P < 0.05) with tumoral size. Since von Hippel-Lindau tumor suppressor, E3 ubiquitin protein ligase, a negative regulator of hypoxia-inducible factor (HIF1)-α, is a downstream molecule of ARNT2, we speculated that HIF1-α and its downstream molecules would have key functions in cellular growth. Consistent with our hypothesis, overexpressed ARNT2 cells showed down-regulation of HIF1-α, which causes hypofunctioning of glucose transporter 1, leading to decreased cellular growth. Our results proposed for the first time that the ARNT2 level is an indicator of cellular proliferation in OSCCs. Therefore, ARNT2 may be a potential therapeutic target against progression of OSCCs. PMID:27076852

  3. ARNT2 Regulates Tumoral Growth in Oral Squamous Cell Carcinoma.

    PubMed

    Kimura, Yasushi; Kasamatsu, Atsushi; Nakashima, Dai; Yamatoji, Masanobu; Minakawa, Yasuyuki; Koike, Kazuyuki; Fushimi, Kazuaki; Higo, Morihiro; Endo-Sakamoto, Yosuke; Shiiba, Masashi; Tanzawa, Hideki; Uzawa, Katsuhiro

    2016-01-01

    Aryl hydrocarbon receptor nuclear translocator (ARNT) 2 is a transcriptional factor related to adaptive responses against cellular stress from a xenobiotic substance. Recent evidence indicates ARNT is involved in carcinogenesis and cancer progression; however, little is known about the relevance of ARNT2 in the behavior of oral squamous cell carcinoma (OSCC). In the current study, we evaluated the ARNT2 mRNA and protein expression levels in OSCC in vitro and in vivo and the clinical relationship between ARNT2 expression levels in primary OSCCs and their clinicopathologic status by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and immunohistochemistry. Using ARNT2 overexpression models, we performed functional analyses to investigate the critical roles of ARNT2 in OSCC. ARNT2 mRNA and protein were down-regulated significantly (P < 0.05 for both comparisons) in nine OSCC-derived cells and primary OSCC (n=100 patients) compared with normal counterparts. In addition to the data from exogenous experiments that ARNT2-overexpressed cells showed decreased cellular proliferation, ARNT2-positive OSCC cases were correlated significantly (P < 0.05) with tumoral size. Since von Hippel-Lindau tumor suppressor, E3 ubiquitin protein ligase, a negative regulator of hypoxia-inducible factor (HIF1)-α, is a downstream molecule of ARNT2, we speculated that HIF1-α and its downstream molecules would have key functions in cellular growth. Consistent with our hypothesis, overexpressed ARNT2 cells showed down-regulation of HIF1-α, which causes hypofunctioning of glucose transporter 1, leading to decreased cellular growth. Our results proposed for the first time that the ARNT2 level is an indicator of cellular proliferation in OSCCs. Therefore, ARNT2 may be a potential therapeutic target against progression of OSCCs. PMID:27076852

  4. Retinal Degeneration Slow (RDS) Glycosylation Plays a Role in Cone Function and in the Regulation of RDS·ROM-1 Protein Complex Formation.

    PubMed

    Stuck, Michael W; Conley, Shannon M; Naash, Muna I

    2015-11-13

    The photoreceptor-specific glycoprotein retinal degeneration slow (RDS, also called PRPH2) is necessary for the formation of rod and cone outer segments. Mutations in RDS cause rod and cone-dominant retinal disease, and it is well established that both cell types have different requirements for RDS. However, the molecular mechanisms for this difference remain unclear. Although RDS glycosylation is highly conserved, previous studies have revealed no apparent function for the glycan in rods. In light of the highly conserved nature of RDS glycosylation, we hypothesized that it is important for RDS function in cones and could underlie part of the differential requirement for RDS in the two photoreceptor subtypes. We generated a knockin mouse expressing RDS without the N-glycosylation site (N229S). Normal levels of RDS and the unglycosylated RDS binding partner rod outer segment membrane protein 1 (ROM-1) were found in N229S retinas. However, cone electroretinogram responses were decreased by 40% at 6 months of age. Because cones make up only 3-5% of photoreceptors in the wild-type background, N229S mice were crossed into the nrl(-/-) background (in which all rods are converted to cone-like cells) for biochemical analysis. In N229S/nrl(-/-) retinas, RDS and ROM-1 levels were decreased by ~60% each. These data suggest that glycosylation of RDS is required for RDS function or stability in cones, a difference that may be due to extracellular versus intradiscal localization of the RDS glycan in cones versus rods. PMID:26420485

  5. New Aspects of Progesterone Interactions with the Actin Cytoskeleton and Neurosteroidogenesis in the Cerebellum and the Neuronal Growth Cone

    PubMed Central

    Wessel, Lisa; Olbrich, Laura; Brand-Saberi, Beate

    2014-01-01

    The impact of progesterone on neuronal tissues in the central (CNS) and peripheral (PNS) nervous system is of significant scientific and therapeutic interest. Glial and neuronal cells of vertebrates express steroidogenic enzymes, and are able to synthesize progesterone de novo from cholesterol. Progesterone is described to have neuroprotective, neuroreparative, anti-degenerative, and anti-apoptotic effects in the CNS and the PNS. Thus, the first clinical studies promise new therapeutic options using progesterone in the treatment of patients with traumatic brain injury. Additionally, experimental data from different animal models suggest further positive effects of progesterone on neurological diseases such as cerebral ischemia, peripheral nerve injury and amyothropic lateral sclerosis. In regard to this future clinical use of progesterone, we discuss in this review the underlying physiological principles of progesterone effects in neuronal tissues. Mechanisms leading to morphological reorganizations of neurons in the CNS and PNS affected by progesterone are addressed, with special focus on the actin cytoskeleton. Furthermore, new aspects of a progesterone-dependent regulation of neurosteroidogenesis mediated by the recently described progesterone binding protein PGRMC1 in the nervous system are discussed. PMID:25141866

  6. Regulation of vascular endothelial growth factor in prostate cancer.

    PubMed

    de Brot, Simone; Ntekim, Atara; Cardenas, Ryan; James, Victoria; Allegrucci, Cinzia; Heery, David M; Bates, David O; Ødum, Niels; Persson, Jenny L; Mongan, Nigel P

    2015-06-01

    Prostate cancer (PCa) is the most common malignancy affecting men in the western world. Although radical prostatectomy and radiation therapy can successfully treat PCa in the majority of patients, up to ~30% will experience local recurrence or metastatic disease. Prostate carcinogenesis and progression is typically an androgen-dependent process. For this reason, therapies for recurrent PCa target androgen biosynthesis and androgen receptor function. Such androgen deprivation therapies (ADT) are effective initially, but the duration of response is typically ≤24 months. Although ADT and taxane-based chemotherapy have delivered survival benefits, metastatic PCa remains incurable. Therefore, it is essential to establish the cellular and molecular mechanisms that enable localized PCas to invade and disseminate. It has long been accepted that metastases require angiogenesis. In the present review, we examine the essential role for angiogenesis in PCa metastases, and we focus in particular on the current understanding of the regulation of vascular endothelial growth factor (VEGF) in localized and metastatic PCa. We highlight recent advances in understanding the role of VEGF in regulating the interaction of cancer cells with tumor-associated immune cells during the metastatic process of PCa. We summarize the established mechanisms of transcriptional and post-transcriptional regulation of VEGF in PCa cells and outline the molecular insights obtained from preclinical animal models of PCa. Finally, we summarize the current state of anti-angiogenesis therapies for PCa and consider how existing therapies impact VEGF signaling. PMID:25870249

  7. Regulation of the photosynthetic apparatus under fluctuating growth light.

    PubMed

    Tikkanen, Mikko; Grieco, Michele; Nurmi, Markus; Rantala, Marjaana; Suorsa, Marjaana; Aro, Eva-Mari

    2012-12-19

    Safe and efficient conversion of solar energy to metabolic energy by plants is based on tightly inter-regulated transfer of excitation energy, electrons and protons in the photosynthetic machinery according to the availability of light energy, as well as the needs and restrictions of metabolism itself. Plants have mechanisms to enhance the capture of energy when light is limited for growth and development. Also, when energy is in excess, the photosynthetic machinery slows down the electron transfer reactions in order to prevent the production of reactive oxygen species and the consequent damage of the photosynthetic machinery. In this opinion paper, we present a partially hypothetical scheme describing how the photosynthetic machinery controls the flow of energy and electrons in order to enable the maintenance of photosynthetic activity in nature under continual fluctuations in white light intensity. We discuss the roles of light-harvesting II protein phosphorylation, thermal dissipation of excess energy and the control of electron transfer by cytochrome b(6)f, and the role of dynamically regulated turnover of photosystem II in the maintenance of the photosynthetic machinery. We present a new hypothesis suggesting that most of the regulation in the thylakoid membrane occurs in order to prevent oxidative damage of photosystem I. PMID:23148275

  8. Regulation of the photosynthetic apparatus under fluctuating growth light

    PubMed Central

    Tikkanen, Mikko; Grieco, Michele; Nurmi, Markus; Rantala, Marjaana; Suorsa, Marjaana; Aro, Eva-Mari

    2012-01-01

    Safe and efficient conversion of solar energy to metabolic energy by plants is based on tightly inter-regulated transfer of excitation energy, electrons and protons in the photosynthetic machinery according to the availability of light energy, as well as the needs and restrictions of metabolism itself. Plants have mechanisms to enhance the capture of energy when light is limited for growth and development. Also, when energy is in excess, the photosynthetic machinery slows down the electron transfer reactions in order to prevent the production of reactive oxygen species and the consequent damage of the photosynthetic machinery. In this opinion paper, we present a partially hypothetical scheme describing how the photosynthetic machinery controls the flow of energy and electrons in order to enable the maintenance of photosynthetic activity in nature under continual fluctuations in white light intensity. We discuss the roles of light-harvesting II protein phosphorylation, thermal dissipation of excess energy and the control of electron transfer by cytochrome b6f, and the role of dynamically regulated turnover of photosystem II in the maintenance of the photosynthetic machinery. We present a new hypothesis suggesting that most of the regulation in the thylakoid membrane occurs in order to prevent oxidative damage of photosystem I. PMID:23148275

  9. A Repressor Protein Complex Regulates Leaf Growth in Arabidopsis

    PubMed Central

    Gonzalez, Nathalie; Pauwels, Laurens; Baekelandt, Alexandra; De Milde, Liesbeth; Van Leene, Jelle; Besbrugge, Nienke; Heyndrickx, Ken S.; Pérez, Amparo Cuéllar; Durand, Astrid Nagels; De Clercq, Rebecca; Van De Slijke, Eveline; Vanden Bossche, Robin; Eeckhout, Dominique; Gevaert, Kris; Vandepoele, Klaas; De Jaeger, Geert; Goossens, Alain; Inzé, Dirk

    2015-01-01

    Cell number is an important determinant of final organ size. In the leaf, a large proportion of cells are derived from the stomatal lineage. Meristemoids, which are stem cell-like precursor cells, undergo asymmetric divisions, generating several pavement cells adjacent to the two guard cells. However, the mechanism controlling the asymmetric divisions of these stem cells prior to differentiation is not well understood. Here, we characterized PEAPOD (PPD) proteins, the only transcriptional regulators known to negatively regulate meristemoid division. PPD proteins interact with KIX8 and KIX9, which act as adaptor proteins for the corepressor TOPLESS. D3-type cyclin encoding genes were identified among direct targets of PPD2, being negatively regulated by PPDs and KIX8/9. Accordingly, kix8 kix9 mutants phenocopied PPD loss-of-function producing larger leaves resulting from increased meristemoid amplifying divisions. The identified conserved complex might be specific for leaf growth in the second dimension, since it is not present in Poaceae (grasses), which also lack the developmental program it controls. PMID:26232487

  10. Cold knife cone biopsy

    MedlinePlus

    A cold knife cone biopsy (conization) is surgery to remove a sample of abnormal tissue from the cervix. The ... Cold knife cone biopsy is done to detect cervical cancer or early changes that lead to cancer. ...

  11. Cold knife cone biopsy

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003910.htm Cold knife cone biopsy To use the sharing features on this page, please enable JavaScript. A cold knife cone biopsy (conization) is surgery to remove ...

  12. Juvenile hormone regulates extreme mandible growth in male stag beetles.

    PubMed

    Gotoh, Hiroki; Cornette, Richard; Koshikawa, Shigeyuki; Okada, Yasukazu; Lavine, Laura Corley; Emlen, Douglas J; Miura, Toru

    2011-01-01

    The morphological diversity of insects is one of the most striking phenomena in biology. Evolutionary modifications to the relative sizes of body parts, including the evolution of traits with exaggerated proportions, are responsible for a vast range of body forms. Remarkable examples of an insect trait with exaggerated proportions are the mandibular weapons of stag beetles. Male stag beetles possess extremely enlarged mandibles which they use in combat with rival males over females. As with other sexually selected traits, stag beetle mandibles vary widely in size among males, and this variable growth results from differential larval nutrition. However, the mechanisms responsible for coupling nutrition with growth of stag beetle mandibles (or indeed any insect structure) remain largely unknown. Here, we demonstrate that during the development of male stag beetles (Cyclommatus metallifer), juvenile hormone (JH) titers are correlated with the extreme growth of an exaggerated weapon of sexual selection. We then investigate the putative role of JH in the development of the nutritionally-dependent, phenotypically plastic mandibles, by increasing hemolymph titers of JH with application of the JH analog fenoxycarb during larval and prepupal developmental periods. Increased JH signaling during the early prepupal period increased the proportional size of body parts, and this was especially pronounced in male mandibles, enhancing the exaggerated size of this trait. The direction of this response is consistent with the measured JH titers during this same period. Combined, our results support a role for JH in the nutrition-dependent regulation of extreme mandible growth in this species. In addition, they illuminate mechanisms underlying the evolution of trait proportion, the most salient feature of the evolutionary diversification of the insects. PMID:21731659

  13. Cone Early Maturity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hop cone early maturity is thought to be caused by diffuse infections of cone, just prior to harvest, by Podosphaera macularis. The disease is best managed by limiting the amount of leaf infection by P. macularis prior to bloom. The yield and quality reductions associated with Hop cone early matur...

  14. Chondroitin-4-sulfation negatively regulates axonal guidance and growth

    PubMed Central

    Wang, Hang; Katagiri, Yasuhiro; McCann, Thomas E.; Unsworth, Edward; Goldsmith, Paul; Yu, Zu-Xi; Tan, Fei; Santiago, Lizzie; Mills, Edward M.; Wang, Yu; Symes, Aviva J.; Geller, Herbert M.

    2008-01-01

    Summary Glycosaminoglycan (GAG) side chains endow extracellular matrix proteoglycans with diversity and complexity based upon the length, composition, and charge distribution of the polysaccharide chain. Using cultured primary neurons, we show that specific sulfation in the GAG chains of chondroitin sulfate (CS) mediates neuronal guidance cues and axonal growth inhibition. Chondroitin-4-sulfate (CS-A), but not chondroitin-6-sulfate (CS-C), exhibits a strong negative guidance cue to mouse cerebellar granule neurons. Enzymatic and gene-based manipulations of 4-sulfation in the GAG side chains alter their ability to direct growing axons. Furthermore, 4-sulfated CS GAG chains are rapidly and significantly increased in regions that do not support axonal regeneration proximal to spinal cord lesions in mice. Thus, our findings provide the evidence showing that specific sulfation along the carbohydrate backbone carries instructions to regulate neuronal function. PMID:18768934

  15. Environmental and toxicological aspects of insect growth regulators.

    PubMed Central

    Wright, J E

    1976-01-01

    Insect growth regulators (IGRs) are a class of new chemicals that interfere with maturation and reproduction in insects. Proposed hypotheses on the biochemical mechanism of action are presented herein. The environmental aspects as metabolism in soils, plants, insects, and animals suggest strongly that these chemicals undergo rapid degradation and metabolism to innocuous metabolites. The toxicological properties determined for registration of the IGR methoprene, isopropyl (E,E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate, reflected no significant effects against any of the species tested. Toxicological evaluations in swine, sheep, hamsters, rats, dogs, rabbits, guinea pigs, and cattle revealed no clinical signs of toxicosis. Additionally, teratological studies in swine, sheep, hamsters, rats, and rabbits also resulted in no observable effects in the animals at the levels administered. PMID:789059

  16. Nodal and Lefty signaling regulates the growth of pancreatic cells

    PubMed Central

    Zhang, You-Qing; Sterling, Lori; Stotland, Aleksandr; Hua, Hong; Kritzik, Marcie; Sarvetnick, Nora

    2014-01-01

    Nodal and its antagonist, Lefty, are important mediators specifying the laterality of the organs during embryogenesis. Nodal signals through activin receptors in the presence of its co-receptor, Cripto. In the present study, we investigated the possible roles of Nodal and Lefty signaling during islet development and regeneration. We found that both Nodal and Lefty are expressed in the pancreas during embryogenesis and islet regeneration. In vitro studies demonstrated that Nodal inhibits, whereas Lefty enhances, the proliferation of a pancreatic cell line. In addition, we showed that Lefty-1 activates MAPK and Akt phosphorylation in these cells. In vivo blockade of endogenous Lefty using neutralizing Lefty-1 monoclonal antibody results in a significantly decreased proliferation of duct epithelial cells during islet regeneration. This is the first study to decipher the expression and function of Nodal and Lefty in pancreatic growth. Importantly, our results highlight a novel function of Nodal-Lefty signaling in the regulation of expansion of pancreatic cells. PMID:18393305

  17. Recoverin depletion accelerates cone photoresponse recovery

    PubMed Central

    Zang, Jingjing; Keim, Jennifer; Kastenhuber, Edda; Gesemann, Matthias; Neuhauss, Stephan C. F.

    2015-01-01

    The neuronal Ca2+-binding protein Recoverin has been shown to regulate phototransduction termination in mammalian rods. Here we identify four recoverin genes in the zebrafish genome, rcv1a, rcv1b, rcv2a and rcv2b, and investigate their role in modulating the cone phototransduction cascade. While Recoverin-1b is only found in the adult retina, the other Recoverins are expressed throughout development in all four cone types, except Recoverin-1a, which is expressed only in rods and UV cones. Applying a double flash electroretinogram (ERG) paradigm, downregulation of Recoverin-2a or 2b accelerates cone photoresponse recovery, albeit at different light intensities. Exclusive recording from UV cones via spectral ERG reveals that knockdown of Recoverin-1a alone has no effect, but Recoverin-1a/2a double-knockdowns showed an even shorter recovery time than Recoverin-2a-deficient larvae. We also showed that UV cone photoresponse kinetics depend on Recoverin-2a function via cone-specific kinase Grk7a. This is the first in vivo study demonstrating that cone opsin deactivation kinetics determine overall photoresponse shut off kinetics. PMID:26246494

  18. Computational insight into the chemical space of plant growth regulators.

    PubMed

    Bushkov, Nikolay A; Veselov, Mark S; Chuprov-Netochin, Roman N; Marusich, Elena I; Majouga, Alexander G; Volynchuk, Polina B; Shumilina, Daria V; Leonov, Sergey V; Ivanenkov, Yan A

    2016-02-01

    An enormous technological progress has resulted in an explosive growth in the amount of biological and chemical data that is typically multivariate and tangled in structure. Therefore, several computational approaches have mainly focused on dimensionality reduction and convenient representation of high-dimensional datasets to elucidate the relationships between the observed activity (or effect) and calculated parameters commonly expressed in terms of molecular descriptors. We have collected the experimental data available in patent and scientific publications as well as specific databases for various agrochemicals. The resulting dataset was then thoroughly analyzed using Kohonen-based self-organizing technique. The overall aim of the presented study is to investigate whether the developed in silico model can be applied to predict the agrochemical activity of small molecule compounds and, at the same time, to offer further insights into the distinctive features of different agrochemical categories. The preliminary external validation with several plant growth regulators demonstrated a relatively high prediction power (67%) of the constructed model. This study is, actually, the first example of a large-scale modeling in the field of agrochemistry. PMID:26723884

  19. Symbiotic regulation of plant growth, development and reproduction

    USGS Publications Warehouse

    Rodriguez, R.J.; Freeman, D. Carl; McArthur, E.D.; Kim, Y.-O.; Redman, R.S.

    2009-01-01

    The growth and development of rice (Oryzae sativa) seedlings was shown to be regulated epigenetically by a fungal endophyte. In contrast to un-inoculated (nonsymbiotic) plants, endophyte colonized (symbiotic) plants preferentially allocated resources into root growth until root hairs were well established. During that time symbiotic roots expanded at five times the rate observed in nonsymbiotic plants. Endophytes also influenced sexual reproduction of mature big sagebrush (Artemisia tridentata) plants. Two spatially distinct big sagebrush subspecies and their hybrids were symbiotic with unique fungal endophytes, despite being separated by only 380 m distance and 60 m elevation. A double reciprocal transplant experiment of parental and hybrid plants, and soils across the hybrid zone showed that fungal endophytes interact with the soils and different plant genotypes to confer enhanced plant reproduction in soil native to the endophyte and reduced reproduction in soil alien to the endophyte. Moreover, the most prevalent endophyte of the hybrid zone reduced the fitness of both parental subspecies. Because these endophytes are passed to the next generation of plants on seed coats, this interaction provides a selective advantage, habitat specificity, and the means of restricting gene flow, thereby making the hybrid zone stable, narrow and potentially leading to speciation. ?? 2009 Landes Bioscience.

  20. Light regulation of the growth response in corn root gravitropism

    NASA Technical Reports Server (NTRS)

    Kelly, M. O.; Leopold, A. C.

    1992-01-01

    Roots of Merit variety corn (Zea mays L.) require red light for orthogravitropic curvature. Experiments were undertaken to identify the step in the pathway from gravity perception to asymmetric growth on which light may act. Red light was effective in inducing gravitropism whether it was supplied concomitant with or as long as 30 minutes after the gravity stimulus (GS). The presentation time was the same whether the GS was supplied in red light or in darkness. Red light given before the GS slightly enhanced the rate of curvature but had little effect on the lag time or on the final curvature. This enhancement was expanded by a delay between the red light pulse and the GS. These results indicate that gravity perception and at least the initial transduction steps proceed in the dark. Light may regulate the final growth (motor) phase of gravitropism. The time required for full expression of the light enhancement of curvature is consistent with its involvement in some light-stimulated biosynthetic event.

  1. Regulation of skeletal muscle capillary growth in exercise and disease.

    PubMed

    Haas, Tara L; Nwadozi, Emmanuel

    2015-12-01

    Capillaries, which are the smallest and most abundant type of blood vessel, form the primary site of gas, nutrient, and waste transfer between the vascular and tissue compartments. Skeletal muscle exhibits the capacity to generate new capillaries (angiogenesis) as an adaptation to exercise training, thus ensuring that the heightened metabolic demand of the active muscle is matched by an improved capacity for distribution of gases, nutrients, and waste products. This review summarizes the current understanding of the regulation of skeletal muscle capillary growth. The multi-step process of angiogenesis is coordinated through the integration of a diverse array of signals associated with hypoxic, metabolic, hemodynamic, and mechanical stresses within the active muscle. The contributions of metabolic and mechanical factors to the modulation of key pro- and anti-angiogenic molecules are discussed within the context of responses to a single aerobic exercise bout and short-term and long-term training. Finally, the paradoxical lack of angiogenesis in peripheral artery disease and diabetes and the implications for disease progression and muscle health are discussed. Future studies that emphasize an integrated analysis of the mechanisms that control skeletal muscle capillary growth will enable development of targeted exercise programs that effectively promote angiogenesis in healthy individuals and in patient populations. PMID:26554747

  2. DUSP10 regulates intestinal epithelial cell growth and colorectal tumorigenesis.

    PubMed

    Png, C W; Weerasooriya, M; Guo, J; James, S J; Poh, H M; Osato, M; Flavell, R A; Dong, C; Yang, H; Zhang, Y

    2016-01-14

    Dual specificity phosphatase 10 (DUSP10), also known as MAP kinase phosphatase 5 (MKP5), negatively regulates the activation of MAP kinases. Genetic polymorphisms and aberrant expression of this gene are associated with colorectal cancer (CRC) in humans. However, the role of DUSP10 in intestinal epithelial tumorigenesis is not clear. Here, we showed that DUSP10 knockout (KO) mice had increased intestinal epithelial cell (IEC) proliferation and migration and developed less severe colitis than wild-type (WT) mice in response to dextran sodium sulphate (DSS) treatment, which is associated with increased ERK1/2 activation and Krüppel-like factor 5 (KLF5) expression in IEC. In line with increased IEC proliferation, DUSP10 KO mice developed more colon tumours with increased severity compared with WT mice in response to administration of DSS and azoxymethane (AOM). Furthermore, survival analysis of CRC patients demonstrated that high DUSP10 expression in tumours was associated with significant improvement in survival probability. Overexpression of DUSP10 in Caco-2 and RCM-1 cells inhibited cell proliferation. Our study showed that DUSP10 negatively regulates IEC growth and acts as a suppressor for CRC. Therefore, it could be targeted for the development of therapies for colitis and CRC. PMID:25772234

  3. [Effects of growth regulators and growth media on root-hair development of Poncirus trifoliate].

    PubMed

    Zhang, De-Jian; Xia, Ren-Xue; Cao, Xiu; Wang, Peng; Shu, Bo

    2011-06-01

    By using river sand and mixed soil as growth media, and treating with different concentration IBA, ETH, and NAA, this paper studied the root-hair development of Poncirus trifoliate seedlings, and the development cycle and distribution pattern of the root-hairs under phosphorus deficiency in sand culture. The root-hairs had a development cycle of about 4 days, and formed block-shaped and clumped, mainly around root, and with uneven distribution. Sand culture gave rise to the production of more root hairs, with an average of 486.3 per tap root, and treating with 1.0 micromol x L(-1) of IBA and ETH notablypromoted root-hair development. The phosphorous deficiency in sand culture induced more roothair formation (636.3 per tap root). Mixed soil culture produced lesser root-hairs (212.3 per taproot), and all the test growth regulators had no obvious effects on the root-hair development. PMID:21941742

  4. Mechanisms of growth cone repulsion

    PubMed Central

    Krull, Catherine E

    2010-01-01

    Research conducted in the last century suggested that chemoattractants guide cells or their processes to appropriate locations during development. Today, we know that many of the molecules involved in cellular guidance can act as chemorepellents that prevent migration into inappropriate territories. Here, we review some of the early seminal experiments and our current understanding of the underlying molecular mechanisms. PMID:20711492

  5. Black hole evolution - I. Supernova-regulated black hole growth

    NASA Astrophysics Data System (ADS)

    Dubois, Yohan; Volonteri, Marta; Silk, Joseph; Devriendt, Julien; Slyz, Adrianne; Teyssier, Romain

    2015-09-01

    The growth of a supermassive black hole (BH) is determined by how much gas the host galaxy is able to feed it, which in turn is controlled by the cosmic environment, through galaxy mergers and accretion of cosmic flows that time how galaxies obtain their gas, and also by internal processes in the galaxy, such as star formation and feedback from stars and the BH itself. In this paper, we study the growth of a 1012 M⊙ halo at z = 2, which is the progenitor of a group of galaxies at z = 0, and of its central BH by means of a high-resolution zoomed cosmological simulation, the Seth simulation. We study the evolution of the BH driven by the accretion of cold gas in the galaxy, and explore the efficiency of the feedback from supernovae (SNe). For a relatively inefficient energy input from SNe, the BH grows at the Eddington rate from early times, and reaches self-regulation once it is massive enough. We find that at early cosmic times z > 3.5, efficient feedback from SNe forbids the formation of a settled disc as well as the accumulation of dense cold gas in the vicinity of the BH and starves the central compact object. As the galaxy and its halo accumulate mass, they become able to confine the nuclear inflows provided by major mergers and the BH grows at a sustained near-to-Eddington accretion rate. We argue that this mechanism should be ubiquitous amongst low-mass galaxies, corresponding to galaxies with a stellar mass below ≲ 109 M⊙ in our simulations.

  6. INFLUENCE OF AN INSECT GROWTH REGULATOR ON LARVAL DEVELOPMENT OF A MARINE CRUSTACEAN

    EPA Science Inventory

    Larval survival, growth, and energy metabolism of an estuarine shrimp (Palaemonetes pugio) were altered by exposure to low micrograms/l concentrations of an insect growth regulator (the juvenile hormone analogue, methoprene). Larvae were several orders of magnitude more sensitive...

  7. Regulation of low affinity neurotrophin receptor (p75NTR) by early growth response (Egr) transcriptional regulators

    PubMed Central

    Gao, Xiaoguang; Daugherty, Rebecca L.; Tourtellotte, Warren G.

    2007-01-01

    The low affinity neurotrophin receptor p75NTR is a multifunctional receptor with important roles in neurotrophin signaling, axon outgrowth, and oligodendroglia and neuron survival. It is transcriptionally regulated with spatial and temporal precision during nervous system development, injury and regeneration. Very little is known about how p75NTR expression is dynamically regulated but it is likely to influence how p75NTR signals in particular cellular contexts. Here, we identify the early growth response (Egr) transcriptional regulators, Egr1 and Egr3, as direct modulators of p75NTR gene expression. Egr1 and Egr3 bind and transactivate the p75NTR promoter in vitro and in vivo, using distinct response elements on the p75NTR promoter. Consistent with these results, p75NTR expression is greatly diminished in muscle spindle stretch receptors and in peripheral nerve Schwann cells in Egr gene deficient mice. Taken together, the results elucidate a novel mechanism whereby Egr proteins can directly modulate p75NTR expression and signaling in vivo. PMID:17916431

  8. [Regulation of osteoclastogenesis by osteocytes through growth differentiation factor-15].

    PubMed

    Hinoi, Eiichi

    2014-01-01

    Osteocytes are the most abundant cells in bone. However, little attention has been paid to their role in bone remodeling. In this study, osteoclast differentiation was significantly enhanced by conditioned media derived from cultures of osteocytic MLO-Y4 cells that were cultured under hypoxic conditions. Using microarray analysis, we identified growth differentiation factor-15 (GDF15) as a pivotal factor secreted from osteocytes under hypoxia. Indeed, treatment with recombinant GDF15 markedly increased osteoclast differentiation in vitro. Further to investigate the importance of GDF15 in vivo, we used a hypoxic murine model that involved ligation of the right femoral artery. The volume of cancellous bone in the proximal tibia of the ligated limb was significantly reduced, together with a significant increase in osteoclast-related parameters. Addition of anti-GDF15 antibody prevented bone loss and osteoclastic activation in the tibiae of mice that had undergone femoral artery ligation. These results suggest that GDF15, which is secreted from osteocytes under hypoxia during bone remodeling, may be a positive regulator of osteoclastic differentiation. The in vivo usefulness of the anti-GDF15 antibody might provide insights for the development of novel therapeutics for bone disorders related to hypoxia or ischemic insults. PMID:25452236

  9. Regulation of scar formation by vascular endothelial growth factor

    PubMed Central

    Wilgus, Traci A.; Ferreira, Ahalia M.; Oberyszyn, Tatiana M.; Bergdall, Valerie K.; DiPietro, Luisa A.

    2009-01-01

    Vascular endothelial growth factor (VEGF-A) is known for its effects on endothelial cells and as a positive mediator of angiogenesis. VEGF is thought to promote the repair of cutaneous wounds due to its pro-angiogenic properties, but its ability to regulate other aspects of wound repair, such as the generation of scar tissue has not been well studied. We examined the role of VEGF in scar tissue production utilizing models of scarless and fibrotic repair. Scarless fetal wounds had lower levels of VEGF and were less vascular than fibrotic fetal wounds, and the scarless phenotype could be converted to a scar-forming phenotype by adding exogenous VEGF. Similarly, neutralization of VEGF reduced vascularity and decreased scar formation in adult wounds. These results show that VEGF levels have a strong influence on scar tissue formation. Our data suggest that VEGF may not simply function as a mediator of wound angiogenesis, but instead may play a more diverse role in the wound repair process. PMID:18427552

  10. Circadian clock regulation of skeletal muscle growth and repair.

    PubMed

    Chatterjee, Somik; Ma, Ke

    2016-01-01

    Accumulating evidence indicates that the circadian clock, a transcriptional/translational feedback circuit that generates ~24-hour oscillations in behavior and physiology, is a key temporal regulatory mechanism involved in many important aspects of muscle physiology. Given the clock as an evolutionarily-conserved time-keeping mechanism that synchronizes internal physiology to environmental cues, locomotor activities initiated by skeletal muscle enable entrainment to the light-dark cycles on earth, thus ensuring organismal survival and fitness. Despite the current understanding of the role of molecular clock in preventing age-related sarcopenia, investigations into the underlying molecular pathways that transmit clock signals to the maintenance of skeletal muscle growth and function are only emerging. In the current review, the importance of the muscle clock in maintaining muscle mass during development, repair and aging, together with its contribution to muscle metabolism, will be discussed. Based on our current understandings of how tissue-intrinsic muscle clock functions in the key aspects muscle physiology, interventions targeting the myogenic-modulatory activities of the clock circuit may offer new avenues for prevention and treatment of muscular diseases. Studies of mechanisms underlying circadian clock function and regulation in skeletal muscle warrant continued efforts. PMID:27540471

  11. Insect growth regulators and insect control: a critical appraisal.

    PubMed Central

    Siddall, J B

    1976-01-01

    Insect growth regulators (IGRs) of the juvenile hormone type alter physiological processes essential to insect development and appear to act specifically on insects. Three natural juvenile hormones have been found in insects but not in other organisms. Future use of antagonists or inhibitors of hormone synthesis may be technically possible as an advantageous extension of pest control by IGRs. A documented survey of the properties, metabolism, toxicology, and uses of the most commercially advanced chemical, methoprene, shows it to be environmentally acceptable and toxicologically innocuous. Derivation of its current use patterns is discussed and limitations on these are noted. Residue levels and their measurement in the ppb region have allowed exemption from the requirement of tolerances in the EPA registered use of methoprene for mosquito control. Tolerances for foods accompany its fully approved use for control of manure breeding flies through a cattle feed supplement. The human health effects of using this chemical appear to be purely beneficial, but further advances through new IGR chemicals appear unlikely without major changes in regulatory and legislative policy. PMID:976222

  12. Circadian clock regulation of skeletal muscle growth and repair

    PubMed Central

    Chatterjee, Somik; Ma, Ke

    2016-01-01

    Accumulating evidence indicates that the circadian clock, a transcriptional/translational feedback circuit that generates ~24-hour oscillations in behavior and physiology, is a key temporal regulatory mechanism involved in many important aspects of muscle physiology. Given the clock as an evolutionarily-conserved time-keeping mechanism that synchronizes internal physiology to environmental cues, locomotor activities initiated by skeletal muscle enable entrainment to the light-dark cycles on earth, thus ensuring organismal survival and fitness. Despite the current understanding of the role of molecular clock in preventing age-related sarcopenia, investigations into the underlying molecular pathways that transmit clock signals to the maintenance of skeletal muscle growth and function are only emerging. In the current review, the importance of the muscle clock in maintaining muscle mass during development, repair and aging, together with its contribution to muscle metabolism, will be discussed. Based on our current understandings of how tissue-intrinsic muscle clock functions in the key aspects muscle physiology, interventions targeting the myogenic-modulatory activities of the clock circuit may offer new avenues for prevention and treatment of muscular diseases. Studies of mechanisms underlying circadian clock function and regulation in skeletal muscle warrant continued efforts. PMID:27540471

  13. The role of collapsing and cone rafting on eruption style changes and final cone morphology: Los Morados scoria cone, Mendoza, Argentina

    NASA Astrophysics Data System (ADS)

    Németh, Karoly; Risso, Corina; Nullo, Francisco; Kereszturi, Gabor

    2011-06-01

    Payún Matru Volcanic Field is a Quaternary monogenetic volcanic field that hosts scoria cones with perfect to breached morphologies. Los Morados complex is a group of at least four closely spaced scoria cones (Los Morados main cone and the older Cones A, B, and C). Los Morados main cone was formed by a long lived eruption of months to years. After an initial Hawaiian-style stage, the eruption changed to a normal Strombolian, conebuilding style, forming a cone over 150 metres high on a northward dipping (˜4°) surface. An initial cone gradually grew until a lava flow breached the cone's base and rafted an estimated 10% of the total volume. A sudden sector collapse initiated a dramatic decompression in the upper part of the feeding conduit and triggered violent a Strombolian style eruptive stage. Subsequently, the eruption became more stable, and changed to a regular Strombolian style that partially rebuilt the cone. A likely increase in magma flux coupled with the gradual growth of a new cone caused another lava flow outbreak at the structurally weakened earlier breach site. For a second time, the unstable flank of the cone was rafted, triggering a second violent Strombolian eruptive stage which was followed by a Hawaiian style lava fountain stage. The lava fountaining was accompanied by a steady outpour of voluminous lava emission accompanied by constant rafting of the cone flank, preventing the healing of the cone. Santa Maria is another scoria cone built on a nearly flat pre-eruption surface. Despite this it went through similar stages as Los Morados main cone, but probably not in as dramatic a manner as Los Morados. In contrast to these examples of large breached cones, volumetrically smaller cones, associated to less extensive lava flows, were able to heal raft/collapse events, due to the smaller magma output and flux rates. Our evidence shows that scoria cone growth is a complex process, and is a consequence of the magma internal parameters (e.g. volatile

  14. Rac regulates vascular endothelial growth factor stimulated motility.

    PubMed

    Soga, N; Connolly, J O; Chellaiah, M; Kawamura, J; Hruska, K A

    2001-01-01

    During angiogenesis endothelial cells migrate towards a chemotactic stimulus. Understanding the mechanism of endothelial cell migration is critical to the therapeutic manipulation of angiogenesis and ultimately cancer prevention. Vascular endothelial growth factor (VEGF) is a potent chemotactic stimulus of endothelial cells during angiogenesis. The endothelial cell signal transduction pathway of VEGF represents a potential target for cancer therapy, but the mechanisms of post-receptor signal transduction including the roles of rho family GTPases in regulating the cytoskeletal effects of VEGF in endothelial cells are not understood. Here we analyze the mechanisms of cell migration in the mouse brain endothelial cell line (bEND3). Stable transfectants containing a tetracycline repressible expression vector were used to induce expression of Rac mutants. Endothelial cell haptotaxis was stimulated by constitutively active V12Rac on collagen and vitronectin coated supports, and chemotaxis was further stimulated by VEGF. Osteopontin coated supports were the most stimulatory to bEND3 haptotaxis, but VEGF was not effective in further increasing migration on osteopontin coated supports. Haptotaxis on support coated with collagen, vitronectin, and to a lesser degree osteopontin was inhibited by N17 Rac. N17 Rac expression blocked stimulation of endothelial cell chemotaxis by VEGF. As part of the chemotactic stimulation, VEGF caused a loss of actin organization at areas of cell-cell contact and increased stress fiber expression in endothelial cells which were directed towards pores in the transwell membrane. N17 Rac prevented the stimulation of cell-cell contact disruption and the stress fiber stimulation by VEGF. These data demonstrate two pathways of regulating endothelial cell motility, one in which Rac is activated by matrix/integrin stimulation and is a crucial modulator of endothelial cell haptotaxis. The other pathway, in the presence of osteopontin, is Rac independent

  15. Regulation and 3 dimensional culture of tertiary follicle growth

    PubMed Central

    2012-01-01

    It has been revealed that multiple cohorts of tertiary follicles develop during some animal estrous cycle and the human menstrual cycle. To reach developmental competence, oocytes need the support of somatic cells. During embryogenesis, the primordial germ cells appear, travel to the gonadal rudiments, and form follicles. The female germ cells develop within the somatic cells of the ovary, granulosa cells, and theca cells. How the oocyte and follicle cells support each other has been seriously studied. The latest technologies in genes and proteins and genetic engineering have allowed us to collect a great deal of information about folliculogenesis. For example, a few web pages (http://www.ncbi.nlm.nih.gov; http://mrg.genetics.washington.edu) provide access to databases of genomes, sequences of transcriptomes, and various tools for analyzing and discovering genes important in ovarian development. Formation of the antrum (tertiary follicle) is the final phase of folliculogenesis and the transition from intraovarian to extraovian regulation. This final step coordinates with the hypothalamic-pituitary-ovarian axis. On the other hand, currently, follicle physiology is under intense investigation, as little is known about how to overcome women's ovarian problems or how to develop competent oocytes from in vitro follicle culture or transplantation. In this review, some of the known roles of hormones and some of the genes involved in tertiary follicle growth and the general characteristics of tertiary follicles are summarized. In addition, in vitro culture of tertiary follicles is also discussed as a study model and an assisted reproductive technology model. PMID:23106040

  16. Effects of growth regulator herbicide on downy brome (Bromus tectorum) seed production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous research showed growth regulator herbicides, such as picloram and aminopyralid, have a sterilizing effect on Japanese brome (Bromus japonicus Thunb.) that can reduce this invasive annual grass’s seed production nearly 100%. This suggests growth regulators might be used to control invasive ...

  17. Dimensional regularization and dimensional reduction in the light cone

    SciTech Connect

    Qiu, J.

    2008-06-15

    We calculate all of the 2 to 2 scattering process in Yang-Mills theory in the light cone gauge, with the dimensional regulator as the UV regulator. The IR is regulated with a cutoff in q{sup +}. It supplements our earlier work, where a Lorentz noncovariant regulator was used, and the final results bear some problems in gauge fixing. Supersymmetry relations among various amplitudes are checked by using the light cone superfields.

  18. Antioxidative activity and growth regulation of Brassicaceae induced by oxygen radical irradiation

    NASA Astrophysics Data System (ADS)

    Hayashi, Nobuya; Ono, Reoto; Shiratani, Masaharu; Yonesu, Akira

    2015-06-01

    The growth regulation characteristics of plants are investigated when plant seeds are irradiated with atmospheric discharge plasma. Enhancement of the germination and lengths of the stem and root of plants are observed after seeding. The total length of the stem and root increases approximately 1.6 times after a cultivation period of 72 h. The growth regulation effect is found to be maintained for 80 h of cultivation after seeding. The growth regulation originates from the change in the antioxidative activity of plant cells induced by active oxygen species generated in the oxygen plasma, which leads to the production of growth factor in plants.

  19. Hormonal regulation of wheat growth during hydroponic culture

    NASA Technical Reports Server (NTRS)

    Wetherell, Donald

    1988-01-01

    Hormonal control of root growth has been explored as one means to alleviate the crowding of plant root systems experienced in prototype hydroponic biomass production chambers being developed by the CELSS Breadboard Project. Four plant hormones, or their chemical analogs, which have been reported to selectively inhibit root growth, were tested by adding them to the nutrient solutions on day 10 of a 25 day growth test using spring wheat in hydroponic cultures. Growth and morphological changes is both shoot and root systems were evaluated. In no case was it possible to inhibit root growth without a comparable inhibition of shoot growth. It was concluded that this approach is unlikely to prove useful for wheat.

  20. Direct observation of mammalian cell growth and size regulation

    PubMed Central

    Son, Sungmin; Tzur, Amit; Weng, Yaochung; Jorgensen, Paul; Kim, Jisoo; Kirschner, Marc W.; Manalis, Scott R.

    2012-01-01

    We introduce a microfluidic system for simultaneously measuring single cell mass and cell cycle progression over multiple generations. We use this system to obtain over 1,000 hours of growth data from mouse lymphoblast and pro-B-cell lymphoid cell lines. Cell lineage analysis revealed a decrease in the growth rate variability at the G1/S phase transition, which suggests the presence of a growth rate threshold for maintaining size homeostasis. PMID:22863882

  1. Comparison of growth and metabolic regulation between wild, domesticated and transgenic salmonids.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To gain a better understanding of the aspects underlying normal and growth hormone enhanced growth in salmonids, quantitative expression analysis was performed for a number of genes related to muscle growth, metabolism, immunology and energy regulation. This analysis was performed in liver and musc...

  2. SIRT1 regulates the mouse gastric emptying and intestinal growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study addressed physiological significance of SIRT1 gene on mouse gastrointestinal growth and function (gastric emptying and intestinal growth). SIRT1 (a NAD+-dependent histone deacetylase) is a key cellular energy sensor, and involved in a wide variety of cellular functions including energy me...

  3. ES1 is a mitochondrial enlarging factor contributing to form mega-mitochondria in zebrafish cones

    PubMed Central

    Masuda, Takamasa; Wada, Yasutaka; Kawamura, Satoru

    2016-01-01

    Total mass of mitochondria increases during cell proliferation and differentiation through mitochondrial biogenesis, which includes mitochondrial proliferation and growth. During the mitochondrial growth, individual mitochondria have been considered to be enlarged independently of mitochondrial fusion. However, molecular basis for this enlarging process has been poorly understood. Cone photoreceptor cells in the retina possess large mitochondria, so-called mega-mitochondria that have been considered to arise via the enlarging process. Here we show that ES1 is a novel mitochondria-enlarging factor contributing to form mega-mitochondria in cones. ES1 is specifically expressed in cones and localized to mitochondria including mega-mitochondria. Knockdown of ES1 markedly reduced the mitochondrial size in cones. In contrast, ectopic expression of ES1 in rods significantly increased both the size of individual mitochondria and the total mass of the mitochondrial cluster without changing the number of them. RNA-seq analysis showed that ERRα and its downstream mitochondrial genes were significantly up-regulated in the ES1-expressing rods, suggesting facilitation of mitochondrial enlargement via ERRα-dependent processes. Furthermore, higher energy state was detected in the ES1-expressing rods, indicating that the enlarged mitochondria by ES1 are capable of producing high energy. ES1 is the mitochondrial protein that is first found to promote enlargement of individual mitochondria. PMID:26926452

  4. ES1 is a mitochondrial enlarging factor contributing to form mega-mitochondria in zebrafish cones.

    PubMed

    Masuda, Takamasa; Wada, Yasutaka; Kawamura, Satoru

    2016-01-01

    Total mass of mitochondria increases during cell proliferation and differentiation through mitochondrial biogenesis, which includes mitochondrial proliferation and growth. During the mitochondrial growth, individual mitochondria have been considered to be enlarged independently of mitochondrial fusion. However, molecular basis for this enlarging process has been poorly understood. Cone photoreceptor cells in the retina possess large mitochondria, so-called mega-mitochondria that have been considered to arise via the enlarging process. Here we show that ES1 is a novel mitochondria-enlarging factor contributing to form mega-mitochondria in cones. ES1 is specifically expressed in cones and localized to mitochondria including mega-mitochondria. Knockdown of ES1 markedly reduced the mitochondrial size in cones. In contrast, ectopic expression of ES1 in rods significantly increased both the size of individual mitochondria and the total mass of the mitochondrial cluster without changing the number of them. RNA-seq analysis showed that ERRα and its downstream mitochondrial genes were significantly up-regulated in the ES1-expressing rods, suggesting facilitation of mitochondrial enlargement via ERRα-dependent processes. Furthermore, higher energy state was detected in the ES1-expressing rods, indicating that the enlarged mitochondria by ES1 are capable of producing high energy. ES1 is the mitochondrial protein that is first found to promote enlargement of individual mitochondria. PMID:26926452

  5. Ecdysone promotes growth of imaginal discs through the regulation of Thor in D. melanogaster.

    PubMed

    Herboso, Leire; Oliveira, Marisa M; Talamillo, Ana; Pérez, Coralia; González, Monika; Martín, David; Sutherland, James D; Shingleton, Alexander W; Mirth, Christen K; Barrio, Rosa

    2015-01-01

    Animals have a determined species-specific body size that results from the combined action of hormones and signaling pathways regulating growth rate and duration. In Drosophila, the steroid hormone ecdysone controls developmental transitions, thereby regulating the duration of the growth period. Here we show that ecdysone promotes the growth of imaginal discs in mid-third instar larvae, since imaginal discs from larvae with reduced or no ecdysone synthesis are smaller than wild type due to smaller and fewer cells. We show that insulin-like peptides are produced and secreted normally in larvae with reduced ecdysone synthesis, and upstream components of insulin/insulin-like signaling are activated in their discs. Instead, ecdysone appears to regulate the growth of imaginal discs via Thor/4E-BP, a negative growth regulator downstream of the insulin/insulin-like growth factor/Tor pathways. Discs from larvae with reduced ecdysone synthesis have elevated levels of Thor, while mutations in Thor partially rescue their growth. The regulation of organ growth by ecdysone is evolutionarily conserved in hemimetabolous insects, as shown by our results obtained using Blattella germanica. In summary, our data provide new insights into the relationship between components of the insulin/insulin-like/Tor and ecdysone pathways in the control of organ growth. PMID:26198204

  6. Ecdysone promotes growth of imaginal discs through the regulation of Thor in D. melanogaster

    PubMed Central

    Herboso, Leire; Oliveira, Marisa M.; Talamillo, Ana; Pérez, Coralia; González, Monika; Martín, David; Sutherland, James D.; Shingleton, Alexander W.; Mirth, Christen K.; Barrio, Rosa

    2015-01-01

    Animals have a determined species-specific body size that results from the combined action of hormones and signaling pathways regulating growth rate and duration. In Drosophila, the steroid hormone ecdysone controls developmental transitions, thereby regulating the duration of the growth period. Here we show that ecdysone promotes the growth of imaginal discs in mid-third instar larvae, since imaginal discs from larvae with reduced or no ecdysone synthesis are smaller than wild type due to smaller and fewer cells. We show that insulin-like peptides are produced and secreted normally in larvae with reduced ecdysone synthesis, and upstream components of insulin/insulin-like signaling are activated in their discs. Instead, ecdysone appears to regulate the growth of imaginal discs via Thor/4E-BP, a negative growth regulator downstream of the insulin/insulin-like growth factor/Tor pathways. Discs from larvae with reduced ecdysone synthesis have elevated levels of Thor, while mutations in Thor partially rescue their growth. The regulation of organ growth by ecdysone is evolutionarily conserved in hemimetabolous insects, as shown by our results obtained using Blattella germanica. In summary, our data provide new insights into the relationship between components of the insulin/insulin-like/Tor and ecdysone pathways in the control of organ growth. PMID:26198204

  7. Growth Factors Regulate Expression of Mineral Associated Genes in Cementoblasts

    PubMed Central

    Saygin, N. Esra; Tokiyasu, Yoshihiko; Giannobile, William V.; Somerman, Martha J.

    2008-01-01

    Background Knowledge of the responsiveness of cells within the periodontal region to specific bioactive agents is important for improving regenerative therapies. The aim of this study was to determine the effect of specific growth factors, insulin-like growth factor-I (IGF-I), platelet-derived growth factor-BB (PDGF-BB), and transforming growth factor-β (TGF-β) on cementoblasts in vitro and ex vivo. Methods Osteocalcin (OC) promoter driven SV40 transgenic mice were used to obtain immortalized cementoblasts. Growth factor effects on DNA synthesis were assayed by [3H]-thymidine incorporation. Northern analysis was used to determine the effects of growth factors on gene expression profile. Effects of growth factors on cementoblast induced biomineralization were determined in vitro (von Kossa stain) and ex vivo (re-implantation of cells in immunodeficient (SCID) mice). Results All growth factors stimulated DNA synthesis compared to control. Twenty-four hour exposure of cells to PDGF-BB or TGF-β resulted in a decrease in bone sialoprotein (BSP) and osteocalcin (OCN) mRNAs while PDGF-BB also increased osteopontin (OPN) mRNA. Cells exposed to IGF-I for 24 hours exhibited decreased transcripts for OCN and OPN with an upregulation of BSP mRNA noted at 72 hours. In vitro mineralization was inhibited by continuous application of PDGF-BB or TGF-β, while cells exposed to these factors prior to implantation into SCID mice still promoted biomineralization. Conclusions These data indicate IGF-I, PDGF-BB, and TGF-β influence mitogenesis, phenotypic gene expression profile, and biomineralization potential of cementoblasts suggesting that such factors alone or in combination with other agents may provide trigger factors required for regenerating periodontal tissues. PMID:11063392

  8. Angiotensin II regulates growth of the developing papillas ex vivo

    PubMed Central

    Song, Renfang; Preston, Graeme; Khalili, Ali; El-Dahr, Samir S.

    2012-01-01

    We tested the hypothesis that lack of angiotensin (ANG) II production in angiotensinogen (AGT)-deficient mice or pharmacologic antagonism of ANG II AT1 receptor (AT1R) impairs growth of the developing papillas ex vivo, thus contributing to the hypoplastic renal medulla phenotype observed in AGT- or AT1R-null mice. Papillas were dissected from Hoxb7GFP+ or AGT+/+, +/−, −/− mouse metanephroi on postnatal day P3 and grown in three-dimentional collagen matrix gels in the presence of media (control), ANG II (10−5 M), or the specific AT1R antagonist candesartan (10−6 M) for 24 h. Percent reduction in papillary length was attenuated in AGT+/+ and in AGT+/− compared with AGT−/− (−18.4 ± 1.3 vs. −32.2 ± 1.6%, P < 0.05, −22.8 ± 1.3 vs. −32.2 ± 1.6%, P < 0.05, respectively). ANG II blunted the decrease in papilla length observed in respective media-treated controls in Hoxb7GFP+ (−1.5 ± 0.3 vs. −10.0 ± 1.4%, P < 0.05) or AGT+/+, +/−, and −/− papillas (−12.8 ± 0.7 vs. −18.4 ± 1.3%, P < 0.05, −16.8 ± 1.1 vs. −23 ± 1.2%, P < 0.05; −26.2 ± 1.6 vs. −32.2 ± 1.6%, P < 0.05, respectively). In contrast, percent decrease in the length of Hoxb7GFP+ papillas in the presence of the AT1R antagonist candesartan was higher compared with control (−24.3 ± 2.1 vs. −10.5 ± 1.8%, P < 0.05). The number of proliferating phospho-histone H3 (pH3)-positive collecting duct cells was lower, whereas the number of caspase 3-positive cells undergoing apoptosis was higher in candesartan- vs. media-treated papillas (pH3: 12 ± 1.4 vs. 21 ± 2.1, P < 0.01; caspase 3: 3.8 ± 0.5 vs. 1.7 ± 0.2, P < 0.01). Using quantitative RT-PCR, we demonstrate that AT1R signaling regulates the expression of genes implicated in morphogenesis of the renal medulla. We conclude that AT1R prevents shrinkage of the developing papillas observed ex vivo via control of Wnt7b, FGF7, β-catenin, calcineurin B1, and α3 integrin gene expression, collecting duct cell

  9. 2017 Eclipse Shadow Cones

    NASA Video Gallery

    A solar eclipse occurs when the Moon's shadow falls on the Earth. The shadow comprises two concentric cones called the umbra and the penumbra. Within the smaller, central umbra, the Sun is complete...

  10. Differentially phased leaf growth and movements in Arabidopsis depend on coordinated circadian and light regulation.

    PubMed

    Dornbusch, Tino; Michaud, Olivier; Xenarios, Ioannis; Fankhauser, Christian

    2014-10-01

    In contrast to vastly studied hypocotyl growth, little is known about diel regulation of leaf growth and its coordination with movements such as changes in leaf elevation angle (hyponasty). We developed a 3D live-leaf growth analysis system enabling simultaneous monitoring of growth and movements. Leaf growth is maximal several hours after dawn, requires light, and is regulated by daylength, suggesting coupling between growth and metabolism. We identify both blade and petiole positioning as important components of leaf movements in Arabidopsis thaliana and reveal a temporal delay between growth and movements. In hypocotyls, the combination of circadian expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5 and their light-regulated protein stability drives rhythmic hypocotyl elongation with peak growth at dawn. We find that PIF4 and PIF5 are not essential to sustain rhythmic leaf growth but influence their amplitude. Furthermore, EARLY FLOWERING3, a member of the evening complex (EC), is required to maintain the correct phase between growth and movement. Our study shows that the mechanisms underlying rhythmic hypocotyl and leaf growth differ. Moreover, we reveal the temporal relationship between leaf elongation and movements and demonstrate the importance of the EC for the coordination of these phenotypic traits. PMID:25281688

  11. Lunar cinder cones.

    PubMed

    McGetchin, T R; Head, J W

    1973-04-01

    Data on terrestrial eruptions of pyroclastic material and ballistic considerations suggest that in the lunar environment (vacuum and reduced gravity) low-rimmed pyroclastic rings are formed rather than the high-rimmed cinder cones so abundant on the earth. Dark blanketing deposits in the Taurus-Littrow region (Apollo 17 landing area) are interpreted as being at least partly composed of lunar counterparts of terrestrial cinder cones. PMID:17757977

  12. Vredefort shatter cones revisited

    NASA Astrophysics Data System (ADS)

    Nicolaysen, L. O.; Reimold, W. U.

    1999-03-01

    Shatter cones have been described from a number of circular and polygonal structures worldwide, the origin of which has been alternatively ascribed to the impacts of large extraterrestrial projectiles or to catastrophic endogenic processes. Despite their association with enigmatic, catastrophic processes, the nature of shatter cones and the physics involved in their formation have not been comprehensively researched. Results of detailed field and laboratory studies of shatter cones from three areas in the collar of the Vredefort Dome in South Africa are presented. Vredefort shatter cones are directly related to a widely displayed fracture phenomenon, termed ``multiply striated joint sets (MSJS)''. MSJs are planar to curviplanar fractures occuring at spacings of <1 to several millimeters. The joint sets have a fractal character. When a new measurement protocol is used in the field, involving study of all joint surfaces and all steps and striae exposed on these surfaces, new information is gained on the genesis and significance of the MSJS and on their relationship to striated conical fractures. The internal constitution of a rock specimen with MSJS was examined in detail, by documenting the precise geometry of many fractures in a suite of parallel thin sections transecting the specimen. The steps and striae on shatter cone surfaces have the characteristics of displacement fractures (microfaults), along which evidence of melting is observed. Shatter cone and MSJS surfaces are often covered with glassy films; we evaluate whether these fracture phenomena are linked to the formation of pseudotachylitic (friction) melt. Our field and petrographic observations can be interpreted as consistent with the generation of shatter cones/MSJS relatively late in the formation of the Vredefort structure. This scenario contrasts sharply with the widely held view that shatter cones are formed during the early ``compression'' phase of a shock event that affected horizontal strata.

  13. AMPK regulation of the growth of cultured human keratinocytes

    SciTech Connect

    Saha, Asish K. . E-mail: aksaha@bu.edu; Persons, Kelly; Safer, Joshua D.; Luo Zhijun; Holick, Michael F.; Ruderman, Neil B.

    2006-10-20

    AMP kinase (AMPK) is a fuel sensing enzyme that responds to cellular energy depletion by increasing processes that generate ATP and inhibiting others that require ATP but are not acutely necessary for survival. In the present study, we examined the relationship between AMPK activation and the growth (proliferation) of cultured human keratinocytes and assessed whether the inhibition of keratinocyte growth by vitamin D involves AMPK activation. In addition, we explored whether the inhibition of keratinocyte proliferation as they approach confluence could be AMPK-related. Keratinocytes were incubated for 12 h with the AMPK activator, 5-aminoimidazole-4-carboxamide-1-{beta}-D-ribofuranoside (AICAR). At concentrations of 10{sup -4} and 10{sup -3} M, AICAR inhibited keratinocyte growth by 50% and 95%, respectively, based on measurements of thymidine incorporation into DNA. It also increased AMPK and acetyl CoA carboxylase phosphorylation (P-AMPK and P-ACC) and decreased the concentration of malonyl CoA confirming that AMPK activation had occurred. Incubation with the thiazolidinedione, troglitazone (10{sup -6} M) caused similar alterations in P-AMPK, P-ACC, and cell growth. In contrast, the well known inhibition of keratinocyte growth by 1,25-dihydroxyvitamin D{sub 3} (10{sup -7} and 10{sup -6} M) was not associated with changes in P-AMPK or P-ACC. Like most cells, the growth of keratinocytes diminished as they approached confluence. Thus, it was of note that we found a progressive increase in P-AMPK (1.5- to 2-fold, p < 0.05) as keratinocytes grown in control medium went from 25% to 100% confluence. In conclusion, the data are consistent with the hypothesis that activation of AMPK acts as a signal to diminish the proliferation of cultured keratinocytes as they approach confluence. They also suggest that AMPK activators, such as AICAR and troglitazone, inhibit keratinocyte growth and that the inhibition of cell growth by 1,25-dihydroxyvitamin D{sub 3} is AMPK-independent.

  14. Information Integration and Communication in Plant Growth Regulation.

    PubMed

    Chaiwanon, Juthamas; Wang, Wenfei; Zhu, Jia-Ying; Oh, Eunkyoo; Wang, Zhi-Yong

    2016-03-10

    Plants are equipped with the capacity to respond to a large number of diverse signals, both internal ones and those emanating from the environment, that are critical to their survival and adaption as sessile organisms. These signals need to be integrated through highly structured intracellular networks to ensure coherent cellular responses, and in addition, spatiotemporal actions of hormones and peptides both orchestrate local cell differentiation and coordinate growth and physiology over long distances. Further, signal interactions and signaling outputs vary significantly with developmental context. This review discusses our current understanding of the integrated intracellular and intercellular signaling networks that control plant growth. PMID:26967291

  15. Genetic Regulation of Phenotypic Plasticity and Canalisation in Yeast Growth.

    PubMed

    Yadav, Anupama; Dhole, Kaustubh; Sinha, Himanshu

    2016-01-01

    The ability of a genotype to show diverse phenotypes in different environments is called phenotypic plasticity. Phenotypic plasticity helps populations to evade extinctions in novel environments, facilitates adaptation and fuels evolution. However, most studies focus on understanding the genetic basis of phenotypic regulation in specific environments. As a result, while it's evolutionary relevance is well established, genetic mechanisms regulating phenotypic plasticity and their overlap with the environment specific regulators is not well understood. Saccharomyces cerevisiae is highly sensitive to the environment, which acts as not just external stimulus but also as signalling cue for this unicellular, sessile organism. We used a previously published dataset of a biparental yeast population grown in 34 diverse environments and mapped genetic loci regulating variation in phenotypic plasticity, plasticity QTL, and compared them with environment-specific QTL. Plasticity QTL is one whose one allele exhibits high plasticity whereas the other shows a relatively canalised behaviour. We mapped phenotypic plasticity using two parameters-environmental variance, an environmental order-independent parameter and reaction norm (slope), an environmental order-dependent parameter. Our results show a partial overlap between pleiotropic QTL and plasticity QTL such that while some plasticity QTL are also pleiotropic, others have a significant effect on phenotypic plasticity without being significant in any environment independently. Furthermore, while some plasticity QTL are revealed only in specific environmental orders, we identify large effect plasticity QTL, which are order-independent such that whatever the order of the environments, one allele is always plastic and the other is canalised. Finally, we show that the environments can be divided into two categories based on the phenotypic diversity of the population within them and the two categories have differential regulators of

  16. Application of plant growth regulators mitigates chlorotic foliar injury by the black pecan aphid (Hemiptera: Aphididae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chlorotic feeding injury by the black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), to pecan (Carya illinoinensis [Wangenh.] K. Koch) foliage can result in leaf senescence and abscission. The plant growth regulators chlorforfenuron (CPPU), gibberellic acid (GA3) and aminoet...

  17. INFLUENCE OF AN INSECT GROWTH REGULATOR ON THE LARVAL DEVELOPMENT OF AN ESTUARINE SHRIMP

    EPA Science Inventory

    The influence of methoprene, an insect growth regulator used in mosquito control, on larval development of the estuarine grass shrimp (Palaemonetes pugio) was examined in the laboratory. o grass shrimp larvae successfully completed metamorphosis when continuously exposed to 1000 ...

  18. Cytokines and growth factors which regulate bone cell function

    NASA Astrophysics Data System (ADS)

    Seino, Yoshiki

    Everybody knows that growth factors are most important in making bone. Hormones enhance bone formation from a long distance. Growth factors promote bone formation as an autocrine or paracrine factor in nearby bone. BMP-2 through BMP-8 are in the TGF-β family. BMP makes bone by enchondral ossification. In bone, IGF-II is most abundant, second, TGF-β, and third IGF-I. TGF-β enhances bone formation mainly by intramembranous ossification in vivo. TGF-β affects both cell proliferation and differentiation, however, TGF-β mainly enhances bone formation by intramembranous ossification. Interestingly, TGF-β is increased by estrogen(E 2), androgen, vitamin D, TGF-β and FGF. IGF-I and IGF-II also enhance bone formation. At present it remains unclear why IGF-I is more active in bone formation than IGF-II, although IGF-II is more abundant in bone compared to IGF-I. However, if only type I receptor signal transduction promotes bone formation, the strong activity of IGF-I in bone formation is understandable. GH, PTH and E 2 promotes IGF-I production. Recent data suggest that hormones containing vitamin D or E 2 enhance bone formation through growth factors. Therefore, growth factors are the key to clarifying the mechanism of bone formation.

  19. Growth Phase dependent gene regulation in Bordetella bronchiseptica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bordetellae are Gram negative bacterial respiratory pathogens. Bordetella pertussis, the causative agent of whooping cough, is a human-restricted variant of Bordetella bronchiseptica, which infects a broad range of mammals causing chronic and often asymptomatic infections. Growth phase dependent gen...

  20. Growth regulation and other secondary effects of herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As all herbicides act on pathways or processes crucial to plants, in an inhibitory or stimulatory way, low doses of any herbicide might be used to beneficially modify plant growth, development, or composition. Glyphosate, the most used herbicide all over the world, is widely applied at low rates to ...

  1. Regulation of liver regeneration by growth factors and cytokines

    PubMed Central

    Böhm, Friederike; Köhler, Ulrike A; Speicher, Tobias; Werner, Sabine

    2010-01-01

    The capability of the liver to fully regenerate after injury is a unique phenomenon essential for the maintenance of its important functions in the control of metabolism and xenobiotic detoxification. The regeneration process is histologically well described, but the genes that orchestrate liver regeneration have been only partially characterized. Of particular interest are cytokines and growth factors, which control different phases of liver regeneration. Historically, their potential functions in this process were addressed by analyzing their expression in the regenerating liver of rodents. Some of the predicted roles were confirmed using functional studies, including systemic delivery of recombinant growth factors, neutralizing antibodies or siRNAs prior to liver injury or during liver regeneration. In particular, the availability of genetically modified mice and their use in liver regeneration studies has unraveled novel and often unexpected functions of growth factors, cytokines and their downstream signalling targets in liver regeneration. This review summarizes the results obtained by functional studies that have addressed the roles and mechanisms of action of growth factors and cytokines in liver regeneration after acute injury to this organ. PMID:20652897

  2. Characterization and estrogen regulation of uterine growth factor activity

    SciTech Connect

    Beck, C.A.

    1988-01-01

    Acid extracts of rat, bovine and rabbit uterus stimulated glucose transport, measured by phosphorylation of 2-deoxyglucose and DNA synthesis, measured by {sup 3}H-thymidne incorporation, in uterine tumor cells and in primary cultures of rat uterine cells. The stimulation of glucose transport was of the same magnitude and followed the same time course as estradiol stimulation in vivo. Uteri from estradiol-treated rat uteri contained 4 times more glucose transport-stimulating activity as control uteri. DNA synthetic activity in rat uterine homogenates was elevated 3-fold within 18-24 h after estradiol injection. Gel filtration showed molecular weight heterogeneity with activity eluting between 10-30 kDA. Both activities were acid and heat stable, were reduced by trypsin but not by dextran-coated charcoal. The effect of purified growth factors on DNA synthesis in primary cultures of rat uterine cells was examined. Epidermal growth factor (EGF), basic fibroblasts growth factor (bFGF), and transforming growth factor-{beta} (TGF{beta}) had no effect on {sup 3}H-thymidine incorporation.

  3. Orchestrated structure evolution: modeling growth-regulated nanomanufacturing.

    PubMed

    Abbasi, Shaghayegh; Kitayaporn, Sathana; Schwartz, Daniel T; Böhringer, Karl F

    2011-04-22

    Orchestrated structure evolution (OSE) is a scalable manufacturing method that combines the advantages of top-down (tool-directed) and bottom-up (self-propagating) approaches. The method consists of a seed patterning step that defines where material nucleates, followed by a growth step that merges seeded islands into the final patterned thin film. We develop a model to predict the completed pattern based on a computationally efficient approximate Green's function solution of the diffusion equation plus a Voronoi diagram based approach that defines the final grain boundary structure. Experimental results rely on electron beam lithography to pattern the seeds, followed by the mass transfer limited growth of copper via electrodeposition. The seed growth model is compared with experimental results to quantify nearest neighbor seed-to-seed interactions as well as how seeds interact with the pattern boundary to impact the local growth rate. Seed-to-seed and seed-to-pattern interactions are shown to result in overgrowth of seeds on edges and corners of the shape, where seeds have fewer neighbors. We explore how local changes to the seed location can be used to improve the patterning quality without increasing the manufacturing cost. OSE is shown to enable a unique set of trade-offs between the cost, time, and quality of thin film patterning. PMID:21393828

  4. Does OsPHR2, central Pi-signaling regulator, regulate some unknown factors crucial for plant growth?

    PubMed Central

    Xu, Jiming

    2010-01-01

    OsPHR2, the homolog of AtPHR1, is a central Pi-signaling regulator. The Pi-signaling pathway downstream of AtPHR1, similarly of OsPHR2,1,2 involves a noncoding RNA which targets mimicry of miR399. miRNA399 mediates cleavage of PHO2.3,4 The regulating pathway downstream of OsPHR2 is negatively regulated by the Pi-signaling responsive gene OsSPX1.5,6 Overexpression of AtPHR1 and OsPHR2 leads to an increased concentration of Pi in the shoot tissues with leaf toxic symptom and growth retardation similar as the phenotype of pho2 mutant, especially under Pi abundant conditions.2,6,7 It has been known that the low affinity Pi transporter OsPT2 mainly contributes to the shoot Pi accumulation mediated by OsPHR2, and overexpression of OsPT2 results in shoot Pi accumulation and leaf toxic symptom and growth retardation under Pi abundant conditions.6 Two curious questions are emerging from the reported results: How Os SPX1 functions on the negative regulation of the pathway and what mechanism of the growth retardation mediated by OsPHR2. For the second question, our favored hypothesis is that the growth inhibition mediated by overexpression of OsPHR2 is caused by toxic physiological effects due to excessive Pi accumulation in shoots (Pi toxicity). In fact, the toxic symptoms become diminished with decreased Pi levels in growth medium. However, the plant growth retardation mediated by overexpression of OsPHR2 may be caused by some unknown genetic factor(s) regulated by OsPHR2. PMID:20404569

  5. Physical and Biological Regulation of Neuron Regenerative Growth and Network Formation on Recombinant Dragline Silks

    PubMed Central

    Huang, Wenwen; He, Jiuyang; Jones, Justin; Lewis, Randolph V.; Kaplan, David L.

    2015-01-01

    Recombinant spider silks produced in transgenic goat milk were studied as cell culture matrices for neuronal growth. Major ampullate spidroin 1 (MaSp1) supported neuronal growth, axon extension and network connectivity, with cell morphology comparable to the gold standard poly-lysine. In addition, neurons growing on MaSp1 films had increased neural cell adhesion molecule (NCAM) expression at both mRNA and protein levels. The results indicate that MaSp1 films present useful surface charge and substrate stiffness to support the growth of primary rat cortical neurons. Moreover, a putative neuron-specific surface binding sequence GRGGL within MaSp1 may contribute to the biological regulation of neuron growth. These findings indicate that MaSp1 could regulate neuron growth through its physical and biological features. This dual regulation mode of MaSp1 could provide an alternative strategy for generating functional silk materials for neural tissue engineering. PMID:25701039

  6. [Luminescent and physiological indices of triticale under the treatment of seeds with growth regulators].

    PubMed

    Kalmatskaia, O A; Karavaev, V A; Gunar, L É; Miakin'kov, A G

    2015-01-01

    It is shown that the before-sowing treatment of triticale seeds with growth regulators epin and zircon resulted in the increase in the F742/F686 ratio of the stationary fluorescence intensities of the plant leaves at the wavelength bands, 742 and 686 nm, corresponding to the maxima in the leaf fluorescence spectrum. Triticale under the treatment of seeds with growth regulators showed higher chlorophyll content, higher productivity and higher indices of the crop yield. PMID:25868356

  7. Understanding Growth in Self-Regulation: International Contributions

    ERIC Educational Resources Information Center

    Morrison, Frederick J.

    2015-01-01

    Over the past decade or so, the importance of self-regulation for academic development and later life success has become increasingly clear (Morrison, Bachman, & Connor, 2005). This article is a commentary regarding the articles in a special issue of "Early Education and Development," which broaden the understanding of the important…

  8. Systems Level Regulation of Rhythmic Growth Rate and Biomass Accumulation in Grasses

    SciTech Connect

    Kay, Steve A.

    2013-05-02

    Several breakthroughs have been recently made in our understanding of plant growth and biomass accumulation. It was found that plant growth is rhythmically controlled throughout the day by the circadian clock through a complex interplay of light and phytohormone signaling pathways. While plants such as the C4 energy crop sorghum (Sorghum bicolor (L.) Moench) and possibly the C3 grass (Brachypodium distachyon) also exhibit daily rhythms in growth rate, the molecular details of its regulation remain to be explored. A better understanding of diurnally regulated growth behavior in grasses may lead to species-specific mechanisms highly relevant to future strategies to optimize energy crop biomass yield. Here we propose to devise a systems approach to identify, in parallel, regulatory hubs associated with rhythmic growth in C3 and C4 plants. We propose to use rhythmicity in daily growth patterns to drive the discovery of regulatory network modules controlling biomass accumulation.

  9. Regulation of gene expression mediating indeterminate muscle growth in teleosts.

    PubMed

    Ahammad, A K Shakur; Asaduzzaman, Md; Asakawa, Shuichi; Watabe, Shugo; Kinoshita, Shigeharu

    2015-08-01

    Teleosts are unique among vertebrates due to their indeterminate muscle growth, i.e., continued production of neonatal muscle fibers until death. However, the molecular mechanism(s) underlying this property is unknown. Here, we focused on the torafugu (Takifugu rubripes) myosin heavy chain gene, MYHM2528-1, which is specifically expressed in neonatal muscle fibers produced by indeterminate muscle growth. We examined the flanking region of MYHM2528-1 through an in vivo reporter assay using zebrafish (Danio rerio) and identified a 2100 bp 5'-flanking sequence that contained sufficient promoter activity to allow specific gene expression. The effects of enhanced promoter activity were observed at the outer region of the fast muscle and the dorsal edge of slow muscle in zebrafish larvae. At the juvenile stage, the promoter was specifically activated in small diameter muscle fibers scattered throughout fast muscle and in slow muscle near the septum separating slow and fast muscles. This spatio-temporal promoter activity overlapped with known myogenic zones involved in teleost indeterminate muscle growth. A deletion mutant analysis revealed that the -2100 to -600 bp 5'flanking sequence of MYHM2528-1 is essential for promoter activity. This region contains putative binding sites for several representative myogenesis-related transcription factors and nuclear factor of activated T-cell (NFAT), a transcription activator involved in regeneration of mammalian adult skeletal muscle. A significant reduction in the promoter activity of the MYHM2528-1 deletion constructs was observed in accordance with a reduction in the number of these binding sites, suggesting the involvement of specific transcription factors in indeterminate muscle growth. PMID:25842264

  10. Early growth response 1 regulates glucose deprivation-induced necrosis

    PubMed Central

    JEON, HYUN MIN; LEE, SU YEON; JU, MIN KYUNG; KIM, CHO HEE; PARK, HYE GYEONG; KANG, HO SUNG

    2013-01-01

    Necrosis is commonly found in the core region of solid tumours due to metabolic stress such as hypoxia and glucose deprivation (GD) resulting from insufficient vascularization. Necrosis promotes tumour growth and development by releasing the tumour-promoting cytokine high mobility group box 1 (HMGB1); however, the molecular mechanism underlying necrotic cell death remains largely unknown. In this study, we show that early growth response 1 (Egr-1) is induced in a reactive oxygen species (ROS)-dependent manner by GD in several cell lines such as A549, MDA-MB-231 and HepG2 cells that exhibit necrosis upon GD. We found that Egr-1 short hairpin RNA (shRNA) prevented GD-induced necrosis and HMGB1 release. Necrosis-inhibiting activity of Egr-1 shRNA was also seen in multicellular tumour spheroids (MTSs), an in vitro tumour model system. In contrast, Egr-1 overexpression appeared to make tumour cells more susceptible to GD-induced necrosis. Finally, Egr-1 shRNA suppressed the growth of MTSs. These findings demonstrate that Egr-1 is implicated in GD-induced necrosis and tumour progression. PMID:23152075

  11. Nitric Oxide Synthase Regulates Growth Coordination During Drosophila melanogaster Imaginal Disc Regeneration.

    PubMed

    Jaszczak, Jacob S; Wolpe, Jacob B; Dao, Anh Q; Halme, Adrian

    2015-08-01

    Mechanisms that coordinate growth during development are essential for producing animals with proper organ proportion. Here we describe a pathway through which tissues communicate to coordinate growth. During Drosophila melanogaster larval development, damage to imaginal discs activates a regeneration checkpoint through expression of Dilp8. This both produces a delay in developmental timing and slows the growth of undamaged tissues, coordinating regeneration of the damaged tissue with developmental progression and overall growth. Here we demonstrate that Dilp8-dependent growth coordination between regenerating and undamaged tissues, but not developmental delay, requires the activity of nitric oxide synthase (NOS) in the prothoracic gland. NOS limits the growth of undamaged tissues by reducing ecdysone biosynthesis, a requirement for imaginal disc growth during both the regenerative checkpoint and normal development. Therefore, NOS activity in the prothoracic gland coordinates tissue growth through regulation of endocrine signals. PMID:26081194

  12. Emergence of robust growth laws from optimal regulation of ribosome synthesis

    PubMed Central

    Scott, Matthew; Klumpp, Stefan; Mateescu, Eduard M; Hwa, Terence

    2014-01-01

    Bacteria must constantly adapt their growth to changes in nutrient availability; yet despite large-scale changes in protein expression associated with sensing, adaptation, and processing different environmental nutrients, simple growth laws connect the ribosome abundance and the growth rate. Here, we investigate the origin of these growth laws by analyzing the features of ribosomal regulation that coordinate proteome-wide expression changes with cell growth in a variety of nutrient conditions in the model organism Escherichia coli. We identify supply-driven feedforward activation of ribosomal protein synthesis as the key regulatory motif maximizing amino acid flux, and autonomously guiding a cell to achieve optimal growth in different environments. The growth laws emerge naturally from the robust regulatory strategy underlying growth rate control, irrespective of the details of the molecular implementation. The study highlights the interplay between phenomenological modeling and molecular mechanisms in uncovering fundamental operating constraints, with implications for endogenous and synthetic design of microorganisms. PMID:25149558

  13. PTH Receptor Signaling in Osteoblasts Regulates Endochondral Vascularization in Maintenance of Postnatal Growth Plate

    PubMed Central

    Qiu, Tao; Xian, Lingling; Crane, Janet; Wen, Chunyi; Hilton, Matthew; Lu, William; Newman, Peter; Cao, Xu

    2016-01-01

    Longitudinal growth of postnatal bone requires precise control of growth plate cartilage chondrocytes and subsequent osteogenesis and bone formation. Little is known about the role of angiogenesis and bone remodeling in maintenance of cartilaginous growth plate. Parathyroid hormone (PTH) stimulates bone remodeling by activating PTH receptor (PTH1R). Mice with conditional deletion of PTH1R in osteoblasts showed disrupted trabecular bone formation. The mice also exhibited postnatal growth retardation with profound defects in growth plate cartilage, ascribable predominantly to a decrease in number of hypertrophic chondrocytes, resulting in premature fusion of the growth plate and shortened long bones. Further characterization of hypertrophic zone and primary spongiosa revealed that endochondral angiogenesis and vascular invasion of the cartilage were impaired, which was associated with aberrant chondrocyte maturation and cartilage development. These studies reveal that PTH1R signaling in osteoblasts regulates cartilaginous growth plate for postnatal growth of bone. PMID:25196529

  14. Microarray and functional analysis of growth-phase dependent gene regulation in Bordetella bronchiseptica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth-phase dependent gene regulation has recently been demonstrated to occur in B. pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. Given that B. pertussis is thought to have derived fro...

  15. Target of rapamycin signaling regulates metabolism, growth, and lifespan in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    TOR is a major nutrition and energy sensor that regulates growth and lifespan in yeast and animals. In plants growth and lifespan are intertwined with not only nutrient acquisition but also nutrition generation and unique aspects of development and differentiation. How TOR functions in these process...

  16. Growth Regulator Herbicides Prevent Invasive Annual grass Seed Production Under Field Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth regulator herbicides, such as 2,4-D, dicamba, picloram, and aminopyralid, are commonly used to control broadleaf weeds in grasslands, non-croplands and cereal crops (e.g. wheat, barley). If applied to cereals at late growth stages, while the grasses are developing reproductive parts, the her...

  17. Effect of Plant Growth Regulators on Phytoremediation of Hexachlorocyclohexane-Contaminated Soil.

    PubMed

    Chouychai, Waraporn; Kruatrachue, Maleeya; Lee, Hung

    2015-01-01

    The influence of three plant growth regulators, indolebutyric acid (IBA), thidiazuron (TDZ) and gibberellic acid (GA3), either individually or in pair-wise combinations, on the ability of waxy corn plant to remove hexachlorocyclohexane (HCH) from contaminated soil was studied. Waxy corn seeds were immersed for 3 h in solutions of 1.0 mg/l IBA, 0.01 mg/l TDZ, 0.1 mg/l GA3, or a mixture of two of the growth regulators, and then inoculated in soil contaminated with 46.8 mg/kg HCH for 30 days. Pretreatment of corn seeds with the plant growth regulators did not enhance corn growth when compared with those immersed in distilled water (control), but the pretreatment enhanced HCH removal significantly. On day 30, HCH concentration in the bulk soil planted with corn seeds pretreated with GA3 or TDZ+GA3 decreased by 97.4% and 98.4%, respectively. In comparison, HCH removal in soil planted with non-pretreated control waxy corn seeds was only 35.7%. The effect of several growth regulator application methods was tested with 0.01 mg/l TDZ. The results showed that none of the methods, which ranged from seed immersion, watering in soil, or spraying on shoots, affected HCH removal from soil. However, the method of applying the growth regulators may affect corn growth. Watering the corn plant with TDZ in soil led to higher root fresh weight (2.2 g) and higher root dried weight (0.57 g) than the other treatments (0.2-1.7 g root fresh weight and 0.02-0.43 g root dried weight) on day 30. Varying the concentrations of GA3 did not affect the enhancement of corn growth and HCH removal on day 30. The results showed that plant growth regulators may have potential for use to enhance HCH phytoremediation. PMID:25985054

  18. DNA Walker-Regulated Cancer Cell Growth Inhibition.

    PubMed

    Li, Feiran; Cha, Tae-Gon; Pan, Jing; Ozcelikkale, Altug; Han, Bumsoo; Choi, Jong Hyun

    2016-06-16

    We demonstrate a DNAzyme-based walker system as a controlled oligonucleotide drug AS1411 release platform for breast cancer treatment. In this system, AS1411 strands are released from fuel strands as a walker moves along its carbon nanotube track. The release rate and amount of anticancer oligonucleotides are controlled by the walker operation. With a walker system embedded within the collagen extracellular matrix, we show that this drug release system can be used for in situ cancer cell growth inhibition. PMID:27059426

  19. Polyamines regulate cell growth and cellular methylglyoxal in high-glucose medium independently of intracellular glutathione.

    PubMed

    Kwak, Min-Kyu; Lee, Mun-Hyoung; Park, Seong-Jun; Shin, Sang-Min; Liu, Rui; Kang, Sa-Ouk

    2016-03-01

    Polyamines can presumably inhibit protein glycation, when associated with the methylglyoxal inevitably produced during glycolysis. Herein, we hypothesized a nonenzymatic interaction between putrescine and methylglyoxal in putrescine-deficient or -overexpressing Dictyostelium cells in high-glucose medium, which can control methylglyoxal production. Putrescine was essentially required for growth rescue accompanying methylglyoxal detoxification when cells underwent growth defect and cell cycle G1-arrest when supplemented with high glucose. Furthermore, methylglyoxal regulation by putrescine seemed to be a parallel pathway independent of the changes in cellular glutathione content in high-glucose medium. Consequently, we suggest that Dictyostelium cells need polyamines for normal growth and cellular methylglyoxal regulation. PMID:26898161

  20. Root growth regulation and gravitropism in maize roots does not require the epidermis

    NASA Technical Reports Server (NTRS)

    Bjorkman, T.; Cleland, R. E.

    1991-01-01

    We have earlier published observations showing that endogenous alterations in growth rate during gravitropism in maize roots (Zea mays L.) are unaffected by the orientation of cuts which remove epidermal and cortical tissue in the growing zone (Bjorkman and Cleland, 1988, Planta 176, 513-518). We concluded that the epidermis and cortex are not essential for transporting a growth-regulating signal in gravitropism or straight growth, nor for regulating the rate of tissue expansion. This conclusion has been challenged by Yang et al. (1990, Planta 180, 530-536), who contend that a shallow girdle around the entire perimeter of the root blocks gravitropic curvature and that this inhibition is the result of a requirement for epidermal cells to transport the growth-regulating signal. In this paper we demonstrate that the entire epidermis can be removed without blocking gravitropic curvature and show that the position of narrow girdles does not affect the location of curvature. We therefore conclude that the epidermis is not required for transport of a growth-regulating substance from the root cap to the growing zone, nor does it regulate the growth rate of the elongating zone of roots.

  1. An integrated network of Arabidopsis growth regulators and its use for gene prioritization

    PubMed Central

    Sabaghian, Ehsan; Drebert, Zuzanna; Inzé, Dirk; Saeys, Yvan

    2015-01-01

    Elucidating the molecular mechanisms that govern plant growth has been an important topic in plant research, and current advances in large-scale data generation call for computational tools that efficiently combine these different data sources to generate novel hypotheses. In this work, we present a novel, integrated network that combines multiple large-scale data sources to characterize growth regulatory genes in Arabidopsis, one of the main plant model organisms. The contributions of this work are twofold: first, we characterized a set of carefully selected growth regulators with respect to their connectivity patterns in the integrated network, and, subsequently, we explored to which extent these connectivity patterns can be used to suggest new growth regulators. Using a large-scale comparative study, we designed new supervised machine learning methods to prioritize growth regulators. Our results show that these methods significantly improve current state-of-the-art prioritization techniques, and are able to suggest meaningful new growth regulators. In addition, the integrated network is made available to the scientific community, providing a rich data source that will be useful for many biological processes, not necessarily restricted to plant growth. PMID:26620795

  2. An expandable, inducible hemangioblast state regulated by fibroblast growth factor.

    PubMed

    Vereide, David T; Vickerman, Vernella; Swanson, Scott A; Chu, Li-Fang; McIntosh, Brian E; Thomson, James A

    2014-12-01

    During development, the hematopoietic and vascular lineages are thought to descend from common mesodermal progenitors called hemangioblasts. Here we identify six transcription factors, Gata2, Lmo2, Mycn, Pitx2, Sox17, and Tal1, that "trap" murine cells in a proliferative state and endow them with a hemangioblast potential. These "expandable" hemangioblasts (eHBs) are capable, once released from the control of the ectopic factors, to give rise to functional endothelial cells, multilineage hematopoietic cells, and smooth muscle cells. The eHBs can be derived from embryonic stem cells, from fetal liver cells, or poorly from fibroblasts. The eHBs reveal a central role for fibroblast growth factor, which not only promotes their expansion, but also facilitates their ability to give rise to endothelial cells and leukocytes, but not erythrocytes. This study serves as a demonstration that ephemeral progenitor states can be harnessed in vitro, enabling the creation of tractable progenitor cell lines. PMID:25458896

  3. Epidermal growth factor system regulates mucin production in airways

    PubMed Central

    Takeyama, Kiyoshi; Dabbagh, Karim; Lee, Heung-Man; Agustí, Carlos; Lausier, James A.; Ueki, Iris F.; Grattan, Kathleen M.; Nadel, Jay A.

    1999-01-01

    Goblet-cell hyperplasia is a critical pathological feature in hypersecretory diseases of airways. However, the underlying mechanisms are unknown, and no effective therapy exists. Here we show that stimulation of epidermal growth factor receptors (EGF-R) by its ligands, EGF and transforming growth factor α (TGFα), causes MUC5AC expression in airway epithelial cells both in in vitro and in vivo. We found that a MUC5AC-inducing epithelial cell line, NCI-H292, expresses EGF-R constitutively; EGF-R gene expression was stimulated further by tumor necrosis factor α (TNFα). EGF-R ligands increased the expression of MUC5AC at both gene and protein levels, and this effect was potentiated by TNFα. Selective EGF-R tyrosine kinase inhibitors blocked MUC5AC expression induced by EGF-R ligands. Pathogen-free rats expressed little EGF-R protein in airway epithelial cells; intratracheal instillation of TNFα induced EGF-R in airway epithelial cells, and subsequent instillation of EGF-R ligands increased the number of goblet cells, Alcian blue–periodic acid–Schiff staining (reflecting mucous glycoconjugates), and MUC5AC gene expression, whereas TNFα, EGF, or TGFα alone was without effect. In sensitized rats, three intratracheal instillations of ovalbumin resulted in EGF-R expression and goblet-cell production in airway epithelium. Pretreatment with EGF-R tyrosine kinase inhibitor, BIBX1522, prevented goblet-cell production both in rats stimulated by TNFα-EGF-R ligands and in an asthma model. These findings suggest potential roles for inhibitors of the EGF-R cascade in hypersecretory diseases of airways. PMID:10077640

  4. Resolving the growth-promoting and metabolic effects of growth hormone: Differential regulation of GH-IGF-I system components.

    PubMed

    Norbeck, Lindsey A; Kittilson, Jeffrey D; Sheridan, Mark A

    2007-05-01

    Growth hormone regulates numerous processes in vertebrates including growth promotion and lipid mobilization. During periods of food deprivation, growth is arrested yet lipid depletion is promoted. In this study, we used rainbow trout on different nutritional regimens to examine the regulation of growth hormone (GH)-insulin-like growth factor-I (IGF-I) system elements in order to resolve the growth-promoting and lipid catabolic actions of GH. Fish fasted for 2 or 6 weeks displayed significantly reduced growth compared to their fed counterparts despite elevated plasma GH, while refeeding for 2 weeks following 4 weeks of fasting partially restored growth and lowered plasma GH. Fish fasted for 6 weeks also exhausted their mesenteric adipose tissue reserves. Sensitivity to GH in the liver was reduced in fasting fish as evidenced by reduced expression of GH receptor type 1 (GHR 1) and GHR 2 mRNAs and by reduced (125)I-GH binding capacity. Expression of GHR 1 and GHR 2 mRNAs also was reduced in the gill of fasted fish. In adipose tissue, however, sensitivity to GH, as indicated by GHR 1 expression and by (125)I-GH binding capacity, increased after 6 weeks of fasting in concert with the observed lipid depletion. Fasting-associated growth retardation was accompanied by reduced expression of total IGF-I mRNA in the liver, adipose and gill, and by reduced plasma levels of IGF-I. Sensitivity to IGF-I was reduced in the gill of fasted fish as indicated by reduced expression of type 1 IGF-I receptor (IGFR 1A and IGFR 1B) mRNAs. By contrast, fasting did not affect expression of IGFR 1 mRNAs or (125)I-IGF-I binding in skeletal muscle and increased expression of IGFR 1 mRNAs and (125)I-IGF-I binding in cardiac muscle. These results indicate that nutritional state differentially regulates GH-IGF-I system components in a tissue-specific manner and that such alterations disable the growth-promoting actions of GH and promote the lipid-mobilizing actions of the hormone. PMID:17376444

  5. Organ-specific regulation of growth-defense tradeoffs by plants.

    PubMed

    Smakowska, Elwira; Kong, Jixiang; Busch, Wolfgang; Belkhadir, Youssef

    2016-02-01

    Plants grow while also defending themselves against phylogenetically unrelated pathogens. Because defense and growth are both costly programs, a plant's success in colonizing resource-scarce environments requires tradeoffs between the two. Here, we summarize efforts aimed at understanding how plants use iterative tradeoffs to modulate differential organ growth when defenses are elicited. First, we focus on shoots to illustrate how light, in conjunction with the growth hormone gibberellin (GA) and the defense hormone jasmonic acid (JA), act to finely regulate defense and growth programs in this organ. Second, we expand on the regulation of growth-defense trade-offs in the root, a less well-studied topic despite the critical role of this organ in acquiring resources in an environment deeply entrenched with disparate populations of microbes. PMID:26802804

  6. Regulation of planar growth by the Arabidopsis AGC protein kinase UNICORN.

    PubMed

    Enugutti, Balaji; Kirchhelle, Charlotte; Oelschner, Maxi; Torres Ruiz, Ramón Angel; Schliebner, Ivo; Leister, Dario; Schneitz, Kay

    2012-09-11

    The spatial coordination of growth is of central importance for the regulation of plant tissue architecture. Individual layers, such as the epidermis, are clonally propagated and structurally maintained by symmetric cell divisions that are oriented along the plane of the layer. The developmental control of this process is poorly understood. The simple cellular basis and sheet-like structure of Arabidopsis integuments make them an attractive model system to address planar growth. Here we report on the characterization of the Arabidopsis UNICORN (UCN) gene. Analysis of ucn integuments reveals localized distortion of planar growth, eventually resulting in an ectopic multicellular protrusion. In addition, ucn mutants exhibit ectopic growth in filaments and petals, as well as aberrant embryogenesis. We further show that UCN encodes an active AGC VIII kinase. Genetic, biochemical, and cell biological data suggest that UCN suppresses ectopic growth in integuments by directly repressing the KANADI transcription factor ABERRANT TESTA SHAPE. Our findings indicate that UCN represents a unique plant growth regulator that maintains planar growth of integuments by repressing a developmental regulator involved in the control of early integument growth and polarity. PMID:22927420

  7. Regulation of planar growth by the Arabidopsis AGC protein kinase UNICORN

    PubMed Central

    Enugutti, Balaji; Kirchhelle, Charlotte; Oelschner, Maxi; Torres Ruiz, Ramón Angel; Schliebner, Ivo; Leister, Dario; Schneitz, Kay

    2012-01-01

    The spatial coordination of growth is of central importance for the regulation of plant tissue architecture. Individual layers, such as the epidermis, are clonally propagated and structurally maintained by symmetric cell divisions that are oriented along the plane of the layer. The developmental control of this process is poorly understood. The simple cellular basis and sheet-like structure of Arabidopsis integuments make them an attractive model system to address planar growth. Here we report on the characterization of the Arabidopsis UNICORN (UCN) gene. Analysis of ucn integuments reveals localized distortion of planar growth, eventually resulting in an ectopic multicellular protrusion. In addition, ucn mutants exhibit ectopic growth in filaments and petals, as well as aberrant embryogenesis. We further show that UCN encodes an active AGC VIII kinase. Genetic, biochemical, and cell biological data suggest that UCN suppresses ectopic growth in integuments by directly repressing the KANADI transcription factor ABERRANT TESTA SHAPE. Our findings indicate that UCN represents a unique plant growth regulator that maintains planar growth of integuments by repressing a developmental regulator involved in the control of early integument growth and polarity. PMID:22927420

  8. Dual Control of Muscle Cell Survival by Distinct Growth Factor-Regulated Signaling Pathways

    PubMed Central

    Lawlor, Margaret A.; Feng, Xiuhong; Everding, Daniel R.; Sieger, Kerry; Stewart, Claire E. H.; Rotwein, Peter

    2000-01-01

    In addition to their ability to stimulate cell proliferation, polypeptide growth factors are able to maintain cell survival under conditions that otherwise lead to apoptotic death. Growth factors control cell viability through regulation of critical intracellular signal transduction pathways. We previously characterized C2 muscle cell lines that lacked endogenous expression of insulin-like growth factor II (IGF-II). These cells did not differentiate but underwent apoptotic death in low-serum differentiation medium. Death could be prevented by IGF analogues that activated the IGF-I receptor or by unrelated growth factors such as platelet-derived growth factor BB (PDGF-BB). Here we analyze the signaling pathways involved in growth factor-mediated myoblast survival. PDGF treatment caused sustained activation of extracellular-regulated kinases 1 and 2 (ERK1 and -2), while IGF-I only transiently induced these enzymes. Transient transfection of a constitutively active Mek1, a specific upstream activator of ERKs, maintained myoblast viability in the absence of growth factors, while inhibition of Mek1 by the drug UO126 blocked PDGF-mediated but not IGF-stimulated survival. Although both growth factors activated phosphatidylinositol 3-kinase (PI3-kinase) to similar extents, only IGF-I treatment led to sustained stimulation of its downstream kinase, Akt. Transient transfection of a constitutively active PI3-kinase or an inducible Akt promoted myoblast viability in the absence of growth factors, while inhibition of PI3-kinase activity by the drug LY294002 selectively blocked IGF- but not PDGF-mediated muscle cell survival. In aggregate, these observations demonstrate that distinct growth factor-regulated signaling pathways independently control myoblast survival. Since IGF action also stimulates muscle differentiation, these results suggest a means to regulate myogenesis through selective manipulation of different signal transduction pathways. PMID:10757809

  9. Spatial Phosphoprotein Profiling Reveals a Compartmentalized Extracellular Signal-regulated Kinase Switch Governing Neurite Growth and Retraction

    SciTech Connect

    Wang, Yingchun; Yang, Feng; Fu, Yi; Huang, Xiahe; Wang, Wei; Jiang, Xining; Gritsenko, Marina A.; Zhao, Rui; Monroe, Matthew E.; Pertz, Olivier C.; Purvine, Samuel O.; Orton, Daniel J.; Jacobs, Jon M.; Camp, David G.; Smith, Richard D.; Klemke, Richard L.

    2011-05-20

    Abstract - Brain development and spinal cord regeneration require neurite sprouting and growth cone navigation in response to extension and collapsing factors present in the extracellular environment. These external guidance cues control neurite growth cone extension and retraction processes through intracellular protein phosphorylation of numerous cytoskeletal, adhesion, and polarity complex signaling proteins. However, the complex kinase/substrate signaling networks that mediate neuritogenesis have not been investigated. Here, we compare the neurite phosphoproteome under growth and retraction conditions using neurite purification methodology combined with mass spectrometry. More than 4000 non-redundant phosphorylation sites from 1883 proteins have been annotated and mapped to signaling pathways that control kinase/phosphatase networks, cytoskeleton remodeling, and axon/dendrite specification. Comprehensive informatics and functional studies revealed a compartmentalized ERK activation/deactivation cytoskeletal switch that governs neurite growth and retraction, respectively. Our findings provide the first system-wide analysis of the phosphoprotein signaling networks that enable neurite growth and retraction and reveal an important molecular switch that governs neuritogenesis.

  10. Mechanical Stress Regulation of Plant Growth and Development

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.

    1985-01-01

    Growth dynamics analysis was used to determine to what extent the seismic stress induced reduction in photosynthetic productivity in shaken soybeans was due to less photosynthetic surface, and to what extent to lower efficiency of assimulation. Seismic stress reduces shoot transpiration rate 17% and 15% during the first and second 45 minute periods following a given treatment. Shaken plants also had a 36% greater leaf water potential 30 minutes after treatment. Continuous measurement of whole plant photosynthetic rate shows that a decline in CO2 fixation began within seconds after the onset of shaking treatment and continued to decline to 16% less than that of controls 20 minutes after shaking, after which gradual recovery of photosynthesis begins. Photosynthetic assimilation recovered completely before the next treatment 5 hours later. The transitory decrease in photosynthetic rate was due entirely to a two fold increase in stomatal resistance to CO2 by the abaxial leaf surface. Mesophyll resistance was not significantly affected by periodic seismic treatment. Temporary stomatal aperture reduction and decreased CO2 fixation are responsible for the lower dry weight of seismic stressed plants growing in a controlled environment.

  11. Regulating continent growth and composition by chemical weathering

    USGS Publications Warehouse

    Lee, C.-T.A.; Morton, D.M.; Little, M.G.; Kistler, R.; Horodyskyj, U.N.; Leeman, W.P.; Agranier, A.

    2008-01-01

    Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms. ?? 2008 by The National Academy of Sciences of the USA.

  12. Regulating continent growth and composition by chemical weathering

    PubMed Central

    Lee, Cin-Ty Aeolus; Morton, Douglas M.; Little, Mark G.; Kistler, Ronald; Horodyskyj, Ulyana N.; Leeman, William P.; Agranier, Arnaud

    2008-01-01

    Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms. PMID:18362343

  13. Evidence That Up-Regulation of MicroRNA-29 Contributes to Postnatal Body Growth Deceleration

    PubMed Central

    Kamran, Fariha; Andrade, Anenisia C.; Nella, Aikaterini A.; Clokie, Samuel J.; Rezvani, Geoffrey; Nilsson, Ola; Baron, Jeffrey

    2015-01-01

    Body growth is rapid in infancy but subsequently slows and eventually ceases due to a progressive decline in cell proliferation that occurs simultaneously in multiple organs. We previously showed that this decline in proliferation is driven in part by postnatal down-regulation of a large set of growth-promoting genes in multiple organs. We hypothesized that this growth-limiting genetic program is orchestrated by microRNAs (miRNAs). Bioinformatic analysis identified target sequences of the miR-29 family of miRNAs to be overrepresented in age–down-regulated genes. Concomitantly, expression microarray analysis in mouse kidney and lung showed that all members of the miR-29 family, miR-29a, -b, and -c, were strongly up-regulated from 1 to 6 weeks of age. Real-time PCR confirmed that miR-29a, -b, and -c were up-regulated with age in liver, kidney, lung, and heart, and their expression levels were higher in hepatocytes isolated from 5-week-old mice than in hepatocytes from embryonic mouse liver at embryonic day 16.5. We next focused on 3 predicted miR-29 target genes (Igf1, Imp1, and Mest), all of which are growth-promoting. A 3′-untranslated region containing the predicted target sequences from each gene was placed individually in a luciferase reporter construct. Transfection of miR-29 mimics suppressed luciferase gene activity for all 3 genes, and this suppression was diminished by mutating the target sequences, suggesting that these genes are indeed regulated by miR-29. Taken together, the findings suggest that up-regulation of miR-29 during juvenile life drives the down-regulation of multiple growth-promoting genes, thus contributing to physiological slowing and eventual cessation of body growth. PMID:25866874

  14. PIF4 Integrates Multiple Environmental and Hormonal Signals for Plant Growth Regulation in Arabidopsis

    PubMed Central

    Choi, Hyunmo; Oh, Eunkyoo

    2016-01-01

    As sessile organisms, plants must be able to adapt to the environment. Plants respond to the environment by adjusting their growth and development, which is mediated by sophisticated signaling networks that integrate multiple environmental and endogenous signals. Recently, increasing evidence has shown that a bHLH transcription factor PIF4 plays a major role in the multiple signal integration for plant growth regulation. PIF4 is a positive regulator in cell elongation and its activity is regulated by various environmental signals, including light and temperature, and hormonal signals, including auxin, gibberellic acid and brassinosteroid, both transcriptionally and post-translationally. Moreover, recent studies have shown that the circadian clock and metabolic status regulate endogenous PIF4 level. The PIF4 transcription factor cooperatively regulates the target genes involved in cell elongation with hormone-regulated transcription factors. Therefore, PIF4 is a key integrator of multiple signaling pathways, which optimizes growth in the environment. This review will discuss our current understanding of the PIF4-mediated signaling networks that control plant growth. PMID:27432188

  15. PIF4 Integrates Multiple Environmental and Hormonal Signals for Plant Growth Regulation in Arabidopsis.

    PubMed

    Choi, Hyunmo; Oh, Eunkyoo

    2016-08-31

    As sessile organisms, plants must be able to adapt to the environment. Plants respond to the environment by adjusting their growth and development, which is mediated by sophisticated signaling networks that integrate multiple environmental and endogenous signals. Recently, increasing evidence has shown that a bHLH transcription factor PIF4 plays a major role in the multiple signal integration for plant growth regulation. PIF4 is a positive regulator in cell elongation and its activity is regulated by various environmental signals, including light and temperature, and hormonal signals, including auxin, gibberellic acid and brassinosteroid, both transcriptionally and post-translationally. Moreover, recent studies have shown that the circadian clock and metabolic status regulate endogenous PIF4 level. The PIF4 transcription factor cooperatively regulates the target genes involved in cell elongation with hormone-regulated transcription factors. Therefore, PIF4 is a key integrator of multiple signaling pathways, which optimizes growth in the environment. This review will discuss our current understanding of the PIF4-mediated signaling networks that control plant growth. PMID:27432188

  16. Integrin β1 regulates leiomyoma cytoskeletal integrity and growth

    PubMed Central

    Malik, Minnie; Segars, James; Catherino, William H.

    2014-01-01

    Uterine leiomyomas are characterized by an excessive extracellular matrix, increased mechanical stress, and increased active RhoA. Previously, we observed that mechanical signaling was attenuated in leiomyoma, but the mechanisms responsible remain unclear. Integrins, especially integrin β1, are transmembrane adhesion receptors that couple extracellular matrix stresses to the intracellular cytoskeleton to influence cell proliferation and differentiation. Here we characterized integrin and laminin to signaling in leiomyoma cells. We observed a 2.25 ± 0.32 fold increased expression of integrin β1 in leiomyoma cells, compared to myometrial cells. Antibody-mediated inhibition of integrin β1 led to significant growth inhibition in leiomyoma cells and a loss of cytoskeletal integrity. Specifically, polymerization of actin filaments and formation of focal adhesions were reduced by inhibition of integrin p1. Inhibition of integrin β1 in leiomyoma cells led to 0.81 ± 0.02 fold decrease in active RhoA, and resembled levels found in serum-starved cells. Likewise, inhibition of integrin β1 was accompanied by a decrease in phospho-ERK. Compared to myometrial cells, leiomyoma cells demonstrated increased expression of integrin α6 subunit to laminin receptor (1.91 ± 0.11 fold), and increased expression of laminin 5α (1.52±0.02), laminin 5β (3.06±0.92), and laminin 5γ (1.66 ± 0.06). Of note, leiomyoma cells grown on laminin matrix appear to realign themselves. Taken together, the findings reveal that the attenuated mechanical signaling in leiomyoma cells is accompanied by an increased expression and a dependence on integrin β1 signaling in leiomyoma cells, compared to myometrial cells. PMID:23023061

  17. GSK3β Regulates Differentiation and Growth Arrest in Glioblastoma

    PubMed Central

    Korur, Serdar; Huber, Roland M.; Sivasankaran, Balasubramanian; Petrich, Michael; Morin, Pier; Hemmings, Brian A.; Merlo, Adrian; Lino, Maria Maddalena

    2009-01-01

    Cancers are driven by a population of cells with the stem cell properties of self-renewal and unlimited growth. As a subpopulation within the tumor mass, these cells are believed to constitute a tumor cell reservoir. Pathways controlling the renewal of normal stem cells are deregulated in cancer. The polycomb group gene Bmi1, which is required for neural stem cell self-renewal and also controls anti-oxidant defense in neurons, is upregulated in several cancers, including medulloblastoma. We have found that Bmi1 is consistently and highly expressed in GBM. Downregulation of Bmi1 by shRNAs induced a differentiation phenotype and reduced expression of the stem cell markers Sox2 and Nestin. Interestingly, expression of glycogen synthase kinase 3 beta (GSK3β), which was found to be consistently expressed in primary GBM, also declined. This suggests a functional link between Bmi1 and GSK3β. Interference with GSK3β activity by siRNA, the specific inhibitor SB216763, or lithium chloride (LiCl) induced tumor cell differentiation. In addition, tumor cell apoptosis was enhanced, the formation of neurospheres was impaired, and clonogenicity reduced in a dose-dependent manner. GBM cell lines consist mainly of CD133-negative (CD133-) cells. Interestingly, ex vivo cells from primary tumor biopsies allowed the identification of a CD133- subpopulation of cells that express stem cell markers and are depleted by inactivation of GSK3β. Drugs that inhibit GSK3, including the psychiatric drug LiCl, may deplete the GBM stem cell reservoir independently of CD133 status. PMID:19823589

  18. FGF signaling in the osteoprogenitor lineage non-autonomously regulates postnatal chondrocyte proliferation and skeletal growth.

    PubMed

    Karuppaiah, Kannan; Yu, Kai; Lim, Joohyun; Chen, Jianquan; Smith, Craig; Long, Fanxin; Ornitz, David M

    2016-05-15

    Fibroblast growth factor (FGF) signaling is important for skeletal development; however, cell-specific functions, redundancy and feedback mechanisms regulating bone growth are poorly understood. FGF receptors 1 and 2 (Fgfr1 and Fgfr2) are both expressed in the osteoprogenitor lineage. Double conditional knockout mice, in which both receptors were inactivated using an osteoprogenitor-specific Cre driver, appeared normal at birth; however, these mice showed severe postnatal growth defects that include an ∼50% reduction in body weight and bone mass, and impaired longitudinal bone growth. Histological analysis showed reduced cortical and trabecular bone, suggesting cell-autonomous functions of FGF signaling during postnatal bone formation. Surprisingly, the double conditional knockout mice also showed growth plate defects and an arrest in chondrocyte proliferation. We provide genetic evidence of a non-cell-autonomous feedback pathway regulating Fgf9, Fgf18 and Pthlh expression, which led to increased expression and signaling of Fgfr3 in growth plate chondrocytes and suppression of chondrocyte proliferation. These observations show that FGF signaling in the osteoprogenitor lineage is obligately coupled to chondrocyte proliferation and the regulation of longitudinal bone growth. PMID:27052727

  19. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective.

    PubMed

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth. PMID:26295391

  20. Spatial Regulation of Root Growth: Placing the Plant TOR Pathway in a Developmental Perspective

    PubMed Central

    Barrada, Adam; Montané, Marie-Hélène; Robaglia, Christophe; Menand, Benoît

    2015-01-01

    Plant cells contain specialized structures, such as a cell wall and a large vacuole, which play a major role in cell growth. Roots follow an organized pattern of development, making them the organs of choice for studying the spatio-temporal regulation of cell proliferation and growth in plants. During root growth, cells originate from the initials surrounding the quiescent center, proliferate in the division zone of the meristem, and then increase in length in the elongation zone, reaching their final size and differentiation stage in the mature zone. Phytohormones, especially auxins and cytokinins, control the dynamic balance between cell division and differentiation and therefore organ size. Plant growth is also regulated by metabolites and nutrients, such as the sugars produced by photosynthesis or nitrate assimilated from the soil. Recent literature has shown that the conserved eukaryotic TOR (target of rapamycin) kinase pathway plays an important role in orchestrating plant growth. We will summarize how the regulation of cell proliferation and cell expansion by phytohormones are at the heart of root growth and then discuss recent data indicating that the TOR pathway integrates hormonal and nutritive signals to orchestrate root growth. PMID:26295391

  1. A response regulator promotes Francisella tularensis intramacrophage growth by repressing an anti-virulence factor.

    PubMed

    Ramsey, Kathryn M; Dove, Simon L

    2016-08-01

    The orphan response regulator PmrA is essential for the intramacrophage growth and survival of Francisella tularensis. PmrA was thought to promote intramacrophage growth by binding directly to promoters on the Francisella Pathogenicity Island (FPI) and positively regulating the expression of FPI genes, which encode a Type VI secretion system required for intramacrophage growth. Using both ChIP-Seq and RNA-Seq we identify those regions of the F. tularensis chromosome occupied by PmrA and those genes that are regulated by PmrA. We find that PmrA associates with 252 distinct regions of the F. tularensis chromosome, but exerts regulatory effects at only a few of these locations. Rather than by functioning directly as an activator of FPI gene expression we present evidence that PmrA promotes intramacrophage growth by repressing the expression of a single target gene we refer to as priM (PmrA-repressed inhibitor of intramacrophage growth). Our findings thus indicate that the role of PmrA in facilitating intracellular growth is to repress a previously unknown anti-virulence factor. PriM is the first bacterially encoded factor to be described that can interfere with the intramacrophage growth and survival of F. tularensis. PMID:27169554

  2. Two-Step Reactivation of Dormant Cones in Retinitis Pigmentosa.

    PubMed

    Wang, Wei; Lee, Sang Joon; Scott, Patrick A; Lu, Xiaoqin; Emery, Douglas; Liu, Yongqin; Ezashi, Toshihiko; Roberts, Michael R; Ross, Jason W; Kaplan, Henry J; Dean, Douglas C

    2016-04-12

    Most retinitis pigmentosa (RP) mutations arise in rod photoreceptor genes, leading to diminished peripheral and nighttime vision. Using a pig model of autosomal-dominant RP, we show glucose becomes sequestered in the retinal pigment epithelium (RPE) and, thus, is not transported to photoreceptors. The resulting starvation for glucose metabolites impairs synthesis of cone visual pigment-rich outer segments (OSs), and then their mitochondrial-rich inner segments dissociate. Loss of these functional structures diminishes cone-dependent high-resolution central vision, which is utilized for most daily tasks. By transplanting wild-type rods, to restore glucose transport, or directly replacing glucose in the subretinal space, to bypass its retention in the RPE, we can regenerate cone functional structures, reactivating the dormant cells. Beyond providing metabolic building blocks for cone functional structures, we show glucose induces thioredoxin-interacting protein (Txnip) to regulate Akt signaling, thereby shunting metabolites toward aerobic glucose metabolism and regenerating cone OS synthesis. PMID:27050517

  3. Two-Step Reactivation of Dormant Cones in Retinitis Pigmentosa

    PubMed Central

    Wang, Wei; Lee, Sang Joon; Scott, Patrick A.; Lu, Xiaoqin; Emery, Douglas; Liu, Yongqin; Ezashi, Toshihiko; Roberts, Michael R.; Ross, Jason W.; Kaplan, Henry J.; Dean, Douglas C.

    2016-01-01

    Most Retinitis Pigmentosa (RP) mutations arise in rod photoreceptor genes, leading to diminished peripheral and nightime vision. Using a pig model of autosomal-dominant RP, we show glucose becomes sequestered in the retinal pigment epithelium (RPE), and thus is not transported to photoreceptors. The resulting starvation for glucose metabolites impairs synthesis of cone visual pigment -rich outer segments (OS), and then their mitochondrial-rich inner segments dissociate. Loss of these functional structures diminishes cone-dependent high-resolution central vision, which is utilized for most daily tasks. By transplanting wild-type rods, to restore glucose transport, or directly replacing glucose in the subretinal space, to bypass its retention in the RPE, we can regenerate cone functional structures, reactivating the dormant cells. Beyond providing metabolic building blocks for cone functional structures, we show glucose induces thioredoxin-interacting protein (Txnip) to regulate Akt signaling, thereby shunting metabolites toward aerobic glucose metabolism and regenerating cone OS synthesis. PMID:27050517

  4. Magma supply rates inferred from cinder cone volumes

    NASA Astrophysics Data System (ADS)

    Bemis, K. G.; Borgia, A.; Neri, M.; Kervyn, M.

    2010-12-01

    Revisiting the question of how cinder cones grow suggests the possibility of inferring magma supply rates from cinder cones sizes. We start with a conceptual model of cinder cone growth: (1) Eruption volume flux increases rapidly and then decreases exponentially. (2) Cinder cones get steeper during the initiation of the eruption and then maintain a constant steepness. (3) The initial basal diameter varies with volume flux into the cone. Based on these constraints, we propose a general form for the relationship between cinder cone volume and magma supply rate: V = Q(exp(-t/b)/b - exp(-t/a)/a), where V is volume (in m3), Q is the maximum potential magma flux (in m3/s), t is time (in s), a is a damping factor (in s) controlling the decline in volume flux, and b is a factor controlling the initial increase in volume flux. Then we use the data available on the growth of cinder cones from four modern eruptions to show the relevance of our model and to constrain the supply curves. All four modern cones (Paricutin, Mexico which erupted 1943-1974; Tolbachik, Kamchatka which erupted in 1975-1976; Cono del Laghetto, Mount Etna, Italy which formed in 2001; and a small cone on the summit of Oldoinyo Lengai, Tanzania, which formed during the 2007 eruption) show the basic growth pattern: initial rapid growth followed by declining growth (Figure 1). The regression results yeild the following magma supply rates: The southern Tolbachik cones have the largest predicted magma supply at ~100 m3/s. Paricutin and Laghetto are around 9 m3/s. The Oldoinyo Lengai cone has a magma supply of ~0.5 m3/s. The northern Tolbachik cone has the lowest magma supply of ~0.1 m3/s. In contrast, the damping factor a is generally on the order of 107 (it varies from 8 x 106 at southern Tolbachik to 4 x 107 at northern Tolbachik). The parameter b controlling the initial increase is generally small (<1). The predicted magma supply does not seem to be very sensitive to either parameter. Thus we suggest that

  5. Endogenous rhythmic growth in oak trees is regulated by internal clocks rather than resource availability

    PubMed Central

    Herrmann, S.; Recht, S.; Boenn, M.; Feldhahn, L.; Angay, O.; Fleischmann, F.; Tarkka, M T.; Grams, T.E.E.; Buscot, F.

    2015-01-01

    Common oak trees display endogenous rhythmic growth with alternating shoot and root flushes. To explore the mechanisms involved, microcuttings of the Quercus robur L. clone DF159 were used for 13C/15N labelling in combination with RNA sequencing (RNASeq) transcript profiling of shoots and roots. The effect of plant internal resource availability on the rhythmic growth of the cuttings was tested through inoculation with the ectomycorrhizal fungus Piloderma croceum. Shoot and root flushes were related to parallel shifts in above- and below-ground C and, to a lesser extent, N allocation. Increased plant internal resource availability by P. croceum inoculation with enhanced plant growth affected neither the rhythmic growth nor the associated resource allocation patterns. Two shifts in transcript abundance were identified during root and shoot growth cessation, and most concerned genes were down-regulated. Inoculation with P. croceum suppressed these transcript shifts in roots, but not in shoots. To identify core processes governing the rhythmic growth, functions [Gene Ontology (GO) terms] of the genes differentially expressed during the growth cessation in both leaves and roots of non-inoculated plants and leaves of P. croceum-inoculated plants were examined. Besides genes related to resource acquisition and cell development, which might reflect rather than trigger rhythmic growth, genes involved in signalling and/or regulated by the circadian clock were identified. The results indicate that rhythmic growth involves dramatic oscillations in plant metabolism and gene regulation between below- and above-ground parts. Ectomycorrhizal symbiosis may play a previously unsuspected role in smoothing these oscillations without modifying the rhythmic growth pattern. PMID:26320242

  6. Endogenous rhythmic growth in oak trees is regulated by internal clocks rather than resource availability.

    PubMed

    Herrmann, S; Recht, S; Boenn, M; Feldhahn, L; Angay, O; Fleischmann, F; Tarkka, M T; Grams, T E E; Buscot, F

    2015-12-01

    Common oak trees display endogenous rhythmic growth with alternating shoot and root flushes. To explore the mechanisms involved, microcuttings of the Quercus robur L. clone DF159 were used for (13)C/(15)N labelling in combination with RNA sequencing (RNASeq) transcript profiling of shoots and roots. The effect of plant internal resource availability on the rhythmic growth of the cuttings was tested through inoculation with the ectomycorrhizal fungus Piloderma croceum. Shoot and root flushes were related to parallel shifts in above- and below-ground C and, to a lesser extent, N allocation. Increased plant internal resource availability by P. croceum inoculation with enhanced plant growth affected neither the rhythmic growth nor the associated resource allocation patterns. Two shifts in transcript abundance were identified during root and shoot growth cessation, and most concerned genes were down-regulated. Inoculation with P. croceum suppressed these transcript shifts in roots, but not in shoots. To identify core processes governing the rhythmic growth, functions [Gene Ontology (GO) terms] of the genes differentially expressed during the growth cessation in both leaves and roots of non-inoculated plants and leaves of P. croceum-inoculated plants were examined. Besides genes related to resource acquisition and cell development, which might reflect rather than trigger rhythmic growth, genes involved in signalling and/or regulated by the circadian clock were identified. The results indicate that rhythmic growth involves dramatic oscillations in plant metabolism and gene regulation between below- and above-ground parts. Ectomycorrhizal symbiosis may play a previously unsuspected role in smoothing these oscillations without modifying the rhythmic growth pattern. PMID:26320242

  7. Regulation of voltage-gated sodium channel expression in cancer: hormones, growth factors and auto-regulation.

    PubMed

    Fraser, Scott P; Ozerlat-Gunduz, Iley; Brackenbury, William J; Fitzgerald, Elizabeth M; Campbell, Thomas M; Coombes, R Charles; Djamgoz, Mustafa B A

    2014-03-19

    Although ion channels are increasingly being discovered in cancer cells in vitro and in vivo, and shown to contribute to different aspects and stages of the cancer process, much less is known about the mechanisms controlling their expression. Here, we focus on voltage-gated Na(+) channels (VGSCs) which are upregulated in many types of carcinomas where their activity potentiates cell behaviours integral to the metastatic cascade. Regulation of VGSCs occurs at a hierarchy of levels from transcription to post-translation. Importantly, mainstream cancer mechanisms, especially hormones and growth factors, play a significant role in the regulation. On the whole, in major hormone-sensitive cancers, such as breast and prostate cancer, there is a negative association between genomic steroid hormone sensitivity and functional VGSC expression. Activity-dependent regulation by positive feedback has been demonstrated in strongly metastatic cells whereby the VGSC is self-sustaining, with its activity promoting further functional channel expression. Such auto-regulation is unlike normal cells in which activity-dependent regulation occurs mostly via negative feedback. Throughout, we highlight the possible clinical implications of functional VGSC expression and regulation in cancer. PMID:24493753

  8. Nucleolin-Mediated RNA Localization Regulates Neuron Growth and Cycling Cell Size.

    PubMed

    Perry, Rotem Ben-Tov; Rishal, Ida; Doron-Mandel, Ella; Kalinski, Ashley L; Medzihradszky, Katalin F; Terenzio, Marco; Alber, Stefanie; Koley, Sandip; Lin, Albina; Rozenbaum, Meir; Yudin, Dmitry; Sahoo, Pabitra K; Gomes, Cynthia; Shinder, Vera; Geraisy, Wasim; Huebner, Eric A; Woolf, Clifford J; Yaron, Avraham; Burlingame, Alma L; Twiss, Jeffery L; Fainzilber, Mike

    2016-08-01

    How can cells sense their own size to coordinate biosynthesis and metabolism with their growth needs? We recently proposed a motor-dependent bidirectional transport mechanism for axon length and cell size sensing, but the nature of the motor-transported size signals remained elusive. Here, we show that motor-dependent mRNA localization regulates neuronal growth and cycling cell size. We found that the RNA-binding protein nucleolin is associated with importin β1 mRNA in axons. Perturbation of nucleolin association with kinesins reduces its levels in axons, with a concomitant reduction in axonal importin β1 mRNA and protein levels. Strikingly, subcellular sequestration of nucleolin or importin β1 enhances axonal growth and causes a subcellular shift in protein synthesis. Similar findings were obtained in fibroblasts. Thus, subcellular mRNA localization regulates size and growth in both neurons and cycling cells. PMID:27477284

  9. Enhanced animal growth via ligand-regulated GHRH myogenic-injectable vectors

    NASA Technical Reports Server (NTRS)

    Draghia-Akli, Ruxandra; Malone, P. Brandon; Hill, Leigh Anne; Ellis, Kenneth M.; Schwartz, Robert J.; Nordstrom, Jeffrey L.

    2002-01-01

    Regulated animal growth occurred following a single electroporated injection of a mixture of two plasmids (10 microg of DNA), one expressing the GeneSwitch regulator protein, the other an inducible growth hormone releasing hormone (GHRH) gene, into the tibialis anterior muscles of adult SCID mice. Administration of the ligand mifepristone (MFP) up-regulated GHRH expression, as shown by elevations of IGF-I levels, and when MFP dosing was withdrawn, IGF-I returned to baseline levels. Five cycles of IGF-I induction were observed during a five-month period. Chronic MFP dosing for 25 days increased lean body mass, weight gain, and bone mineral density significantly compared with non-MFP treated controls. In summary, long-term drug-regulated GHRH expression was achieved following plasmid-based gene therapy, and chronic induction of GHRH expression in adult animals led to improvements in weight gain and body composition.

  10. Growth Factor Dependent Regulation of Centrosome Function and Genomic Instability by HuR

    PubMed Central

    Filippova, Natalia; Yang, Xiuhua; Nabors, Louis Burt

    2015-01-01

    The mRNA binding protein HuR is over expressed in cancer cells and contributes to disease progression through post-transcriptional regulation of mRNA. The regulation of HuR and how this relates to glioma is the focus of this report. SRC and c-Abl kinases regulate HuR sub-cellular trafficking and influence accumulation in the pericentriolar matrix (PCM) via a growth factor dependent signaling mechanism. Growth factor stimulation of glioma cell lines results in the associate of HuR with the PCM and amplification of centrosome number. This process is regulated by tyrosine phosphorylation of HuR and is abolished by mutating tyrosine residues. HuR is overexpressed in tumor samples from patients with glioblastoma and associated with a reduced survival. These findings suggest HuR plays a significant role in centrosome amplification and genomic instability, which contributes to a worse disease outcome. PMID:25803745

  11. The turnover of mineralized growth plate cartilage into bone may be regulated by osteocytes.

    PubMed

    Cox, Lieke G E; van Rietbergen, B; van Donkelaar, C C; Ito, K

    2011-06-01

    During endochondral ossification, growth plate cartilage is replaced with bone. Mineralized cartilage matrix is resorbed by osteoclasts, and new bone tissue is formed by osteoblasts. As mineralized cartilage does not contain any cells, it is unclear how this process is regulated. We hypothesize that, in analogy with bone remodeling, osteoclast and osteoblast activity are regulated by osteocytes, in response to mechanical loading. Since the cartilage does not contain osteocytes, this means that cartilage turnover during endochondral ossification would be regulated by the adjacent bone tissue. We investigated this hypothesis with an established computational bone adaptation model. In this model, osteocytes stimulate osteoblastic bone formation in response to the mechanical bone tissue loading. Osteoclasts resorb bone near randomly occurring microcracks that are assumed to block osteocyte signals. We used finite element modeling to evaluate our hypothesis in a 2D-domain representing part of the growth plate and adjacent bone. Cartilage was added at a constant physiological rate to simulate growth. Simulations showed that osteocyte signals from neighboring bone were sufficient for successful cartilage turnover, since equilibrium between cartilage remodeling and growth was obtained. Furthermore, there was good agreement between simulated bone structures and rat tibia histology, and the development of the trabecular architecture resembled that of infant long bones. Additionally, prohibiting osteoclast invasion resulted in thickened mineralized cartilage, similar to observations in a knock-out mouse model. We therefore conclude that it is well possible that osteocytes regulate the turnover of mineralized growth plate cartilage. PMID:21546025

  12. Differential Methylation during Maize Leaf Growth Targets Developmentally Regulated Genes1[C][W][OPEN

    PubMed Central

    Candaele, Jasper; Demuynck, Kirin; Mosoti, Douglas; Beemster, Gerrit T.S.; Inzé, Dirk; Nelissen, Hilde

    2014-01-01

    DNA methylation is an important and widespread epigenetic modification in plant genomes, mediated by DNA methyltransferases (DMTs). DNA methylation is known to play a role in genome protection, regulation of gene expression, and splicing and was previously associated with major developmental reprogramming in plants, such as vernalization and transition to flowering. Here, we show that DNA methylation also controls the growth processes of cell division and cell expansion within a growing organ. The maize (Zea mays) leaf offers a great tool to study growth processes, as the cells progressively move through the spatial gradient encompassing the division zone, transition zone, elongation zone, and mature zone. Opposite to de novo DMTs, the maintenance DMTs were transcriptionally regulated throughout the growth zone of the maize leaf, concomitant with differential CCGG methylation levels in the four zones. Surprisingly, the majority of differentially methylated sequences mapped on or close to gene bodies and not to repeat-rich loci. Moreover, especially the 5′ and 3′ regions of genes, which show overall low methylation levels, underwent differential methylation in a developmental context. Genes involved in processes such as chromatin remodeling, cell cycle progression, and growth regulation, were differentially methylated. The presence of differential methylation located upstream of the gene anticorrelated with transcript expression, while gene body differential methylation was unrelated to the expression level. These data indicate that DNA methylation is correlated with the decision to exit mitotic cell division and to enter cell expansion, which adds a new epigenetic level to the regulation of growth processes. PMID:24488968

  13. Growth Hormone-Regulated mRNAs and miRNAs in Chicken Hepatocytes

    PubMed Central

    Wang, Huijuan; Shao, Fang; Yu, JianFeng; Jiang, Honglin; Han, Yaoping; Gong, Daoqing; Gu, Zhiliang

    2014-01-01

    Growth hormone (GH) is a key regulatory factor in animal growth, development and metabolism. Based on the expression level of the GH receptor, the chicken liver is a major target organ of GH, but the biological effects of GH on the chicken liver are not fully understood. In this work we identified mRNAs and miRNAs that are regulated by GH in primary hepatocytes from female chickens through RNA-seq, and analyzed the functional relevance of these mRNAs and miRNAs through GO enrichment analysis and miRNA target prediction. A total of 164 mRNAs were found to be differentially expressed between GH-treated and control chicken hepatocytes, of which 112 were up-regulated and 52 were down-regulated by GH. A total of 225 chicken miRNAs were identified by the RNA-Seq analysis. Among these miRNAs 16 were up-regulated and 1 miRNA was down-regulated by GH. The GH-regulated mRNAs were mainly involved in growth and metabolism. Most of the GH-upregulated or GH-downregulated miRNAs were predicted to target the GH-downregulated or GH-upregulated mRNAs, respectively, involved in lipid metabolism. This study reveals that GH regulates the expression of many mRNAs involved in metabolism in female chicken hepatocytes, which suggests that GH plays an important role in regulating liver metabolism in female chickens. The results of this study also support the hypothesis that GH regulates lipid metabolism in chicken liver in part by regulating the expression of miRNAs that target the mRNAs involved in lipid metabolism. PMID:25386791

  14. Effects of scoria-cone eruptions upon nearby human communities

    USGS Publications Warehouse

    Ort, M.H.; Elson, M.D.; Anderson, K.C.; Duffield, W.A.; Hooten, J.A.; Champion, D.E.; Waring, G.

    2008-01-01

    Scoria-cone eruptions are typically low in volume and explosivity compared with eruptions from stratovolcanoes, but they can affect local populations profoundly. Scoria-cone eruption effects vary dramatically due to eruption style, tephra blanket extent, climate, types of land use, the culture and complexity of the affected group, and resulting governmental action. A comparison of a historic eruption (Pari??cutin, Me??xico) with prehistoric eruptions (herein we primarily focus on Sunset Crater in northern Arizona, USA) elucidates the controls on and effects of these variables. Long-term effects of lava flows extend little beyond the flow edges. These flows, however, can be used for defensive purposes, providing refuges from invasion for those who know them well. In arid lands, tephra blankets serve as mulches, decreasing runoff and evaporation, increasing infiltration, and regulating soil temperature. Management and retention of these scoria mulches, which can open new areas for agriculture, become a priority for farming communities. In humid areas, though, the tephra blanket may impede plant growth and increase erosion. Cultural responses to eruptions vary, from cultural collapse, through fragmentation of society, dramatic changes, and development of new technologies, to little apparent change. Eruptions may also be viewed as retribution for poor behavior, and attempts are made to mollify angry gods. ?? 2008 Geological Society of America.

  15. Nav1.5 regulates breast tumor growth and metastatic dissemination in vivo

    PubMed Central

    Nelson, Michaela; Yang, Ming; Millican-Slater, Rebecca; Brackenbury, William J.

    2015-01-01

    Voltage-gated Na+ channels (VGSCs) mediate action potential firing and regulate adhesion and migration in excitable cells. VGSCs are also expressed in cancer cells. In metastatic breast cancer (BCa) cells, the Nav1.5 α subunit potentiates migration and invasion. In addition, the VGSC-inhibiting antiepileptic drug phenytoin inhibits tumor growth and metastasis. However, the functional activity of Nav1.5 and its specific contribution to tumor progression in vivo has not been delineated. Here, we found that Nav1.5 is up-regulated at the protein level in BCa compared with matched normal breast tissue. Na+ current, reversibly blocked by tetrodotoxin, was retained in cancer cells in tumor tissue slices, thus directly confirming functional VGSC activity in vivo. Stable down-regulation of Nav1.5 expression significantly reduced tumor growth, local invasion into surrounding tissue, and metastasis to liver, lungs and spleen in an orthotopic BCa model. Nav1.5 down-regulation had no effect on cell proliferation or angiogenesis within the in tumors, but increased apoptosis. In vitro, Nav1.5 down-regulation altered cell morphology and reduced CD44 expression, suggesting that VGSC activity may regulate cellular invasion via the CD44-src-cortactin signaling axis. We conclude that Nav1.5 is functionally active in cancer cells in breast tumors, enhancing growth and metastatic dissemination. These findings support the notion that compounds targeting Nav1.5 may be useful for reducing metastasis. PMID:26452220

  16. Methionine sulfoxide reductase A regulates cell growth through the p53-p21 pathway

    SciTech Connect

    Choi, Seung Hee; Kim, Hwa-Young

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Down-regulation of MsrA inhibits normal cell proliferation. Black-Right-Pointing-Pointer MsrA deficiency leads to an increase in p21 by enhanced p53 acetylation. Black-Right-Pointing-Pointer Down-regulation of MsrA causes cell cycle arrest at the G{sub 2}/M stage. Black-Right-Pointing-Pointer MsrA is a regulator of cell growth that mediates the p53-p21 pathway. -- Abstract: MsrA is an oxidoreductase that catalyzes the stereospecific reduction of methionine-S-sulfoxide to methionine. Although MsrA is well-characterized as an antioxidant and has been implicated in the aging process and cellular senescence, its roles in cell proliferation are poorly understood. Here, we report a critical role of MsrA in normal cell proliferation and describe the regulation mechanism of cell growth by this protein. Down-regulation of MsrA inhibited cell proliferation, but MsrA overexpression did not promote it. MsrA deficiency led to an increase in p21, a major cyclin-dependent kinase inhibitor, thereby causing cell cycle arrest at the G{sub 2}/M stage. While protein levels of p53 were not altered upon MsrA deficiency, its acetylation level was significantly elevated, which subsequently activated p21 transcription. The data suggest that MsrA is a regulator of cell growth that mediates the p53-p21 pathway.

  17. Regulation of integrin and growth factor signaling in biomaterials for osteodifferentiation

    PubMed Central

    Wei, Qiang; Pohl, Theresa L M; Seckinger, Anja

    2015-01-01

    Summary Stem cells respond to the microenvironment (niche) they are located in. Under natural conditions, the extracellular matrix (ECM) is the essential component the in stem cell niche, in which both integrin ligands and growth factors are important regulators to directly or indirectly modulate the cell behavior. In this review, we summarize the current knowledge about the potential of integrin ligands and growth factors to induce osteogenic differentiation of stem cells, and discuss the signaling pathways that are initiated by both individual and cooperative parameters. The joint effect of integrin ligands and growth factors is highlighted as the multivalent interactions for bone therapy. PMID:26124879

  18. Emerging role of PLAG1 as a regulator of growth and reproduction.

    PubMed

    Juma, Almas R; Damdimopoulou, Pauliina E; Grommen, Sylvia V H; Van de Ven, Wim J M; De Groef, Bert

    2016-02-01

    Pleomorphic adenoma gene 1 (PLAG1) belongs to the PLAG family of zinc finger transcription factors along with PLAG-like 1 and PLAG-like 2. The PLAG1 gene is best known as an oncogene associated with certain types of cancer, most notably pleomorphic adenomas of the salivary gland. While the mechanisms of PLAG1-induced tumorigenesis are reasonably well understood, the role of PLAG1 in normal physiology is less clear. It is known that PLAG1 is involved in cell proliferation by directly regulating a wide array of target genes, including a number of growth factors such as insulin-like growth factor 2. This is likely to be a central mode of action for PLAG1 both in embryonic development and in cancer. The phenotype of Plag1 knockout mice suggests an important role for PLAG1 also in postnatal growth and reproduction, as PLAG1 deficiency causes growth retardation and reduced fertility. A role for PLAG1 in growth and reproduction is further corroborated by genome-wide association studies in humans and domestic animals in which polymorphisms in the PLAG1 genomic region are associated with body growth and reproductive traits. Here we review the current evidence for PLAG1 as a regulator of growth and fertility and discuss possible endocrine mechanisms involved. PMID:26577933

  19. Annexin V/beta5 integrin interactions regulate apoptosis of growth plate chondrocytes.

    PubMed

    Wang, Wei; Kirsch, Thorsten

    2006-10-13

    Apoptosis of terminally differentiated chondrocytes allows the replacement of growth plate cartilage by bone. Despite its importance, little is known about the regulation of chondrocyte apoptosis. We show that overexpression of annexin V, which binds to the cytoplasmic domain of beta5 integrin and protein kinase C alpha (PKCalpha), stimulates apoptotic events in hypertrophic growth plate chondrocytes. To determine whether the balance between the interactions of annexin V/beta5 integrin and annexin V/active PKCalpha play a role in the regulation of terminally differentiated growth plate chondrocyte apoptosis, a peptide mimic of annexin V (Penetratin (Pen)-VVISYSMPD) that binds to beta5 integrin but not to PKCalpha was used. This peptide stimulated apoptotic events in growth plate chondrocytes. Suppression of annexin V expression using small interfering ribonucleic acid decreased caspase-3 activity and increased cell viability in Pen-VVISYSMPD-treated growth plate chondrocytes. An activator of PKC resulted in a further decrease of cell viability and further increase of caspase-3 activity in Pen-VVISYSMPD-treated growth plate chondrocytes, whereas inhibitors of PKCalpha led to an increase of cell viability and decrease of caspase-3 activity of Pen-VVISYSMPD-treated cells. These findings suggest that binding of annexin V to active PKCalpha stimulates apoptotic events in growth plate chondrocytes and that binding of annexin Vto beta5 integrin controls these interactions and ultimately apoptosis. PMID:16914549

  20. Regulation of early human growth: impact on long-term health.

    PubMed

    Koletzko, Berthold; Chourdakis, Michael; Grote, Veit; Hellmuth, Christian; Prell, Christine; Rzehak, Peter; Uhl, Olaf; Weber, Martina

    2014-01-01

    Growth and development are central characteristics of childhood. Deviations from normal growth can indicate serious health challenges. The adverse impact of early growth faltering and malnutrition on later health has long been known. In contrast, the impact of rapid early weight and body fat gain on programming of later disease risk have only recently received increased attention. Numerous observational studies related diet in early childhood and rapid early growth to the risk of later obesity and associated disorders. Causality was confirmed in a large, double-blind randomised trial testing the 'Early Protein Hypothesis'. In this trial we found that attenuation of protein supply in infancy normalized early growth and markedly reduced obesity prevalence in early school age. These results indicate the need to describe and analyse growth patterns and their regulation through diet in more detail and to characterize the underlying metabolic and epigenetic mechanisms, given the potential major relevance for public health and policy. Better understanding of growth patterns and their regulation could have major benefits for the promotion of public health, consumer-orientated nutrition recommendations, and the development of improved food products for specific target populations. PMID:25413647

  1. A multilevel latent growth modelling of the longitudinal changes in motivation regulations in physical education.

    PubMed

    Jaakkola, Timo; Wang, John; Yli-Piipari, Sami; Liukkonen, Jarmo

    2015-03-01

    The purpose of this study was to examine individual- and classroom-level differences in the longitudinal change in motivational regulations during physical education students' transition from elementary (Grade 6) across middle school (Grades 7 to 9). A sample of 757 Finnish adolescents (M = 12.71, SD = 0.23) participated in this study. Participants of the study responded to questionnaires collected six times. A multilevel latent growth modelling approach was used to analyze the data. Results showed that motivational regulations in physical education developed at different rates during middle school. More specifically, students': (a) identified regulation increased across Grades 6 to 9; (b) amotivation increased during middle school transition from Grade 6 to 7; and (c) introjected regulation declined from Grade 8 to 9. Other motivational regulations remained stable across time. The changes in amotivation and introjected regulation were largely due to individual factors, whereas the changes in identified regulation were due to environmental factors. Key pointsStudents' identified regulation increased across Grades 6 to 9.Students' amotivation increased across middle school transition from Grade 6 to 7.Students' introjected regulation declined from Grade 8 to 9.Other motivational regulations remained stable across time. PMID:25729304

  2. A Multilevel Latent Growth Modelling of the Longitudinal Changes in Motivation Regulations in Physical Education

    PubMed Central

    Jaakkola, Timo; Wang, John; Yli-Piipari, Sami; Liukkonen, Jarmo

    2015-01-01

    The purpose of this study was to examine individual- and classroom-level differences in the longitudinal change in motivational regulations during physical education students’ transition from elementary (Grade 6) across middle school (Grades 7 to 9). A sample of 757 Finnish adolescents (M = 12.71, SD = 0.23) participated in this study. Participants of the study responded to questionnaires collected six times. A multilevel latent growth modelling approach was used to analyze the data. Results showed that motivational regulations in physical education developed at different rates during middle school. More specifically, students’: (a) identified regulation increased across Grades 6 to 9; (b) amotivation increased during middle school transition from Grade 6 to 7; and (c) introjected regulation declined from Grade 8 to 9. Other motivational regulations remained stable across time. The changes in amotivation and introjected regulation were largely due to individual factors, whereas the changes in identified regulation were due to environmental factors. Key points Students’ identified regulation increased across Grades 6 to 9. Students’ amotivation increased across middle school transition from Grade 6 to 7. Students’ introjected regulation declined from Grade 8 to 9. Other motivational regulations remained stable across time. PMID:25729304

  3. Light cone matrix product

    SciTech Connect

    Hastings, Matthew B

    2009-01-01

    We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.

  4. Discovery of an ergosterol-signaling factor that regulates Trypanosoma brucei growth[S

    PubMed Central

    Haubrich, Brad A.; Singha, Ujjal K.; Miller, Matthew B.; Nes, Craigen R.; Anyatonwu, Hosanna; Lecordier, Laurence; Patkar, Presheet; Leaver, David J.; Villalta, Fernando; Vanhollebeke, Benoit; Chaudhuri, Minu; Nes, W. David

    2015-01-01

    Ergosterol biosynthesis and homeostasis in the parasitic protozoan Trypanosoma brucei was analyzed by RNAi silencing and inhibition of sterol C24β-methyltransferase (TbSMT) and sterol 14α-demethylase [TbSDM (TbCYP51)] to explore the functions of sterols in T. brucei growth. Inhibition of the amount or activity of these enzymes depletes ergosterol from cells at <6 fg/cell for procyclic form (PCF) cells or <0.01 fg/cell for bloodstream form (BSF) cells and reduces infectivity in a mouse model of infection. Silencing of TbSMT expression by RNAi in PCF or BSF in combination with 25-azalanosterol (AZA) inhibited parasite growth and this inhibition was restored completely by adding synergistic cholesterol (7.8 μM from lipid-depleted media) with small amounts of ergosterol (1.2 μM) to the medium. These observations are consistent with the proposed requirement for ergosterol as a signaling factor to spark cell proliferation while imported cholesterol or the endogenously formed cholesta-5,7,24-trienol act as bulk membrane components. To test the potential chemotherapeutic importance of disrupting ergosterol biosynthesis using pairs of mechanism-based inhibitors that block two enzymes in the post-squalene segment, parasites were treated with AZA and itraconazole at 1 μM each (ED50 values) resulting in parasite death. Taken together, our results demonstrate that the ergosterol pathway is a prime drug target for intervention in T. brucei infection. PMID:25424002

  5. Searching for baits with insect growth regulating effects on an invasive crazy ant, Nylanderia pubens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nylanderia pubens is an invasive ant that is currently plaguing parts of Florida and Texas with extremely high populations that dominate landscapes. It is hypothesized that insect growth regulating (IGR) ant baits would be distributed more efficiently among multiple colonies of N. pubens than fast...

  6. Methodology for evaluating the insect growth regulator (IGR) methoprene incorporated into packaging films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The insect growth regulator methoprene has been impregnated onto various packaging materials to control stored product insects, and is labeled for use in this manner in the United States. Different methodologies were utilized to evaluate efficacy towards Tribolium castaneum (Herbst), the red flour b...

  7. Economics of growth regulator treatment of alfalfa seed for interseeding into silage corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies have focused on interseeding of alfalfa into corn for use as a temporary cover crop rather than as a means of jump-starting alfalfa production after corn. In ongoing field studies, we are evaluating whether plant growth regulators (PGR) may be used to aid the establishment of inters...

  8. Residual efficacy of the insect growth regulator pyriproxyfen for control of stored product insects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The insect growth regulator pyriproxyfen is registered in the USA as an aerosol and as a surface treatment to control stored product insects. Field trials with the aerosol show that residues from an application of pyrethrin + pyriproxyfen gave residual control of the red flour beetle, Tribolium cast...

  9. Shaping Self-Regulation in Science Teachers' Professional Growth: Inquiry Skills

    ERIC Educational Resources Information Center

    Michalsky, Tova

    2012-01-01

    This study examined 188 preservice science teachers' professional growth along three dimensions--self-regulated learning (SRL) in a science pedagogical context, pedagogical content knowledge, and self-efficacy in teaching science--comparing four learner-centered, active-learning, peer-collaborative environments for learning to teach higher order…

  10. A possible novel black aphid control approach using plant growth regulators

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), elicits localized chlorotic injury to pecan foliage in order to feed, thereby accelerating leaf senescence and defoliation. The action of certain plant growth regulators (i.e., forchlorfenuron, gibberellic acid and avi...

  11. Growth regulators and chemicals stimulate germination of leafy spurge seeds (Euphorbia esula)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to survey the effect of various growth regulator and chemical treatments on germination of leafy spurge seeds. Non-treated seeds in this population were nearly fully imbibed in 3 h and display approximately 35% germination in 21 d under the normal alternating temperature of ...

  12. The F-BAR Protein PACSIN2 Regulates Epidermal Growth Factor Receptor Internalization

    PubMed Central

    de Kreuk, Bart-Jan; Anthony, Eloise C.; Geerts, Dirk; Hordijk, Peter L.

    2012-01-01

    Signaling via growth factor receptors, including the epidermal growth factor (EGF) receptor, is key to various cellular processes, such as proliferation, cell survival, and cell migration. In a variety of human diseases such as cancer, aberrant expression and activation of growth factor receptors can lead to disturbed signaling. Intracellular trafficking is crucial for proper signaling of growth factor receptors. As a result, the level of cell surface expression of growth factor receptors is an important determinant for the outcome of downstream signaling. BAR domain-containing proteins represent an important family of proteins that regulate membrane dynamics. In this study, we identify a novel role for the F-BAR protein PACSIN2 in the regulation of EGF receptor signaling. We show that internalized EGF as well as the (activated) EGF receptor translocated to PACSIN2-positive endosomes. Furthermore, loss of PACSIN2 increased plasma membrane expression of the EGF receptor in resting cells and increased EGF-induced phosphorylation of the EGF receptor. As a consequence, EGF-induced activation of Erk and Akt as well as cell proliferation were enhanced in PACSIN2-depleted cells. In conclusion, this study identifies a novel role for the F-BAR-domain protein PACSIN2 in regulating EGF receptor surface levels and EGF-induced downstream signaling. PMID:23129763

  13. Arabidopsis RIC1 Severs Actin Filaments at the Apex to Regulate Pollen Tube Growth

    PubMed Central

    Zhou, Zhenzhen; Shi, Haifan; Chen, Binqing; Zhang, Ruihui; Huang, Shanjin; Fu, Ying

    2015-01-01

    Pollen tubes deliver sperms to the ovule for fertilization via tip growth. The rapid turnover of F-actin in pollen tube tips plays an important role in this process. In this study, we demonstrate that Arabidopsis thaliana RIC1, a member of the ROP-interactive CRIB motif-containing protein family, regulates pollen tube growth via its F-actin severing activity. Knockout of RIC1 enhanced pollen tube elongation, while overexpression of RIC1 dramatically reduced tube growth. Pharmacological analysis indicated that RIC1 affected F-actin dynamics in pollen tubes. In vitro biochemical assays revealed that RIC1 directly bound and severed F-actin in the presence of Ca2+ in addition to interfering with F-actin turnover by capping F-actin at the barbed ends. In vivo, RIC1 localized primarily to the apical plasma membrane (PM) of pollen tubes. The level of RIC1 at the apical PM oscillated during pollen tube growth. The frequency of F-actin severing at the apex was notably decreased in ric1-1 pollen tubes but was increased in pollen tubes overexpressing RIC1. We propose that RIC1 regulates F-actin dynamics at the apical PM as well as the cytosol by severing F-actin and capping the barbed ends in the cytoplasm, establishing a novel mechanism that underlies the regulation of pollen tube growth. PMID:25804540

  14. CREB-binding protein regulates lung cancer growth by targeting MAPK and CPSF4 signaling pathway.

    PubMed

    Tang, Zhipeng; Yu, Wendan; Zhang, Changlin; Zhao, Shilei; Yu, Zhenlong; Xiao, Xiangsheng; Tang, Ranran; Xuan, Yang; Yang, Wenjing; Hao, Jiaojiao; Xu, Tingting; Zhang, Qianyi; Huang, Wenlin; Deng, Wuguo; Guo, Wei

    2016-02-01

    CBP (CREB-binding protein) is a transcriptional co-activator which possesses HAT (histone acetyltransferases) activity and participates in many biological processes, including embryonic development, growth control and homeostasis. However, its roles and the underlying mechanisms in the regulation of carcinogenesis and tumor development remain largely unknown. Here we investigated the molecular mechanisms and potential targets of CBP involved in tumor growth and survival in lung cancer cells. Elevated expression of CBP was detected in lung cancer cells and tumor tissues compared to the normal lung cells and tissues. Knockdown of CBP by siRNA or inhibition of its HAT activity using specific chemical inhibitor effectively suppressed cell proliferation, migration and colony formation and induced apoptosis in lung cancer cells by inhibiting MAPK and activating cytochrome C/caspase-dependent signaling pathways. Co-immunoprecipitation and immunofluorescence analyses revealed the co-localization and interaction between CBP and CPSF4 (cleavage and polyadenylation specific factor 4) proteins in lung cancer cells. Knockdown of CPSF4 inhibited hTERT transcription and cell growth induced by CBP, and vice versa, demonstrating the synergetic effect of CBP and CPSF4 in the regulation of lung cancer cell growth and survival. Moreover, we found that high expression of both CBP and CPSF4 predicted a poor prognosis in the patients with lung adenocarcinomas. Collectively, our results indicate that CBP regulates lung cancer growth by targeting MAPK and CPSF4 signaling pathways. PMID:26628108

  15. Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts

    SciTech Connect

    DiCicco-Bloom, E.; Black, I.B. )

    1988-06-01

    While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. The authors have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating ({sup 3}H)thymidine into their nuclei. They used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of ({sup 3}H)thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. The observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain.

  16. Progressive cone dystrophies.

    PubMed

    François, J; De Rouck, A; De Laey, J J

    1976-01-01

    Patients with progressive generalized cone dystrophy often present nystagmus (or strabism) and complain of photophobia, decrease in visual acuity or disturbances in colour perception. The most classic fundus abnormality is the bull's eye maculopathy or a pallor of the optic disc. Minimal macular changes are sometimes seen, which may progress to a bull's eye type of macular degeneration. The photopic ERG is always very affected, whereas at first the scotopic ERG seems normal. Progressive deterioration of the visual functions is accompanied by increasing fundus lesions and rod involvement, as suggested by the modifications of the dark adaptation curve and the scotopic ERG. However, the progression of typical generalized cone dysfunction is very slow. On the contrary, in some cases of so-called Stargardt's disease with peripheral participation, a very rapid progression has been observed. In such cases a normal ERG does not necessarily mean that the disease will remain localized to the macular area. No definite prognosis can be made on one single ERG. In 3 cases with sector pigmentary retinopathy the photopic ERG was more affected than the scotopic ERG. However, these cases are probably primary cone-rod dystrophies. Although there is no electrophysiological control, our clinical impression is that the evolution, if possible, is very slow. PMID:1066593

  17. miR-526a regulates apoptotic cell growth in human carcinoma cells.

    PubMed

    Yang, Xiaoli; Wang, Cui; Xu, Changzhi; Yan, Zhifeng; Wei, Congwen; Guan, Kai; Ma, Shengli; Cao, Ye; Liu, Liping; Zou, Deyong; He, Xiang; Zhang, Buchang; Ma, Qingjun; Zheng, Zirui

    2015-09-01

    MicroRNAs (miRNAs) play vital roles in the regulation of cell cycle, cell growth, apoptosis, and tumorigenesis. Our previous studies showed that miR-526a positively regulated innate immune response by suppressing CYLD expression, however, the functional relevance of miR-526a expression and cell growth remains to be evaluated. In this study, miR-526a overexpression was found to promote cancer cell proliferation, migration, and anchor-independent colony formation. The molecular mechanism(s) of miR-526a-mediated growth stimulation is associated with rapid cell cycle progression and inhibition of cell apoptosis by targeting CYLD. Taken together, these results provide evidence to show the stimulatory role of miR-526a in tumor migration and invasion through modulation of the canonical NF-κB signaling pathway. PMID:26002288

  18. Laminin-511, inducer of hair growth, is down-regulated and its suppressor in hair growth, laminin-332 up-regulated in chemotherapy-induced alopecia

    PubMed Central

    Imanishi, Hisayoshi; Tsuruta, Daisuke; Tateishi, Chiharu; Sugawara, Koji; Paus, Ralf; Tsuji, Tsutomu; Ishii, Masamitsu; Ikeda, Kazuo; Kunimoto, Hiroyuki; Nakajima, Koichi; Jones, Jonathan C.R.; Kobayashi, Hiromi

    2010-01-01

    Background Chemotherapy-induced alopecia (CIA) has a devastating cosmetic effect, especially in the young. Recent data indicate that two major basement membrane components (laminin-332 and -511) of the skin have opposing effects on hair growth. Objective In this study, we examined the role and localization of laminin-332 and -511 in CIA. Methods We examined the expression of laminin-332 and -511 during the dystrophic catagen form of CIA induced in C57BL/6 mice by cyclophosphamide (CYP) treatment. Results Our data indicate that both laminin-332 and its receptor α6β4 integrin are up-regulated (both quantitatively and spatially) after mid to late dystrophic catagen around the outer root sheath (ORS) in the lower third of hair follicles in CIA. This up-regulation also occurs at the transcriptional level. In contrast, laminin-511 is down-regulated after mid dystrophic catagen at the protein level, with transcriptional inactivation of laminin-511 occurring transiently at the early dystrophic catagen stage in both epidermal and ORS keratinocytes. Laminin-511 expression correlates with expression of α3 integrin in CIA and we also demonstrate that laminin-511 can up-regulate the activity of the α3 integrin promoter in cultured keratinocytes. Injection of a laminin-511 rich protein extract, but not recombinant laminin-332, in the back skin of mice delays hair loss in CYP-induced CIA. Conclusions We propose that abrupt hair loss in CIA is, at least in part, caused by down-regulation of laminin-511 and up-regulation of laminin-332 at the transcriptional and translational levels. PMID:20211547

  19. Cell Wall Nonlinear Elasticity and Growth Dynamics: How Do Bacterial Cells Regulate Pressure and Growth?

    NASA Astrophysics Data System (ADS)

    Deng, Yi

    In my thesis, I study intact and bulging Escherichia coli cells using atomic force microscopy to separate the contributions of the cell wall and turgor pressure to the overall cell stiffness. I find strong evidence of power--law stress--stiffening in the E. coli cell wall, with an exponent of 1.22±0.12, such that the wall is significantly stiffer in intact cells (E = 23±8 MPa and 49±20 MPa in the axial and circumferential directions) than in unpressurized sacculi. These measurements also indicate that the turgor pressure in living cells E. coli is 29±3 kPa. The nonlinearity in cell elasticity serves as a plausible mechanism to balance the mechanical protection and tension measurement sensitivity of the cell envelope. I also study the growth dynamics of the Bacillus subtilis cell wall to help understand the mechanism of the spatiotemporal order of inserting new cell wall material. High density fluorescent markers are used to label the entire cell surface to capture the morphological changes of the cell surface at sub-cellular to diffraction-limited spatial resolution and sub-minute temporal resolution. This approach reveals that rod-shaped chaining B. subtilis cells grow and twist in a highly heterogeneous fashion both spatially and temporally. Regions of high growth and twisting activity have a typical length scale of 5 μm, and last for 10-40 minutes. Motivated by the quantification of the cell wall growth dynamics, two microscopy and image analysis techniques are developed and applied to broader applications beyond resolving bacterial growth. To resolve densely distributed quantum dots, we present a fast and efficient image analysis algorithm, namely Spatial Covariance Reconstruction (SCORE) microscopy that takes into account the blinking statistics of the fluorescence emitters. We achieve sub-diffraction lateral resolution of 100 nm from 5 to 7 seconds of imaging, which is at least an order of magnitude faster than single-particle localization based methods

  20. Shatter cones: Diagnostic impact signatures

    NASA Technical Reports Server (NTRS)

    Mchone, J. F.; Dietz, R. S.

    1988-01-01

    Uniquely fractured target rocks known as shatter cones are associated with more than one half the world's 120 or so presently known impact structures. Shatter cones are a form of tensile rock failure in which a positive conical plug separates from a negative outer cup or mold and delicate ornaments radiating from an apex are preserved on surfaces of both portions. Although distinct, shatter cones are sometimes confused with other striated geologic features such as ventifacts, stylolites, cone-in-cone, slickensides, and artificial blast plumes. Complete cones or solitary cones are rare, occurrences are usually as swarms in thoroughly fractured rock. Shatter cones may form in a zone where an expanding shock wave propagating through a target decays to form an elastic wave. Near this transition zone, the expanding primary wave may strike a pebble or other inhomogeneity whose contrasting transmission properties produce a scattered secondary wave. Interference between primary and secondary scattered waves produce conical stress fields with axes perpendicular to the plane of an advancing shock front. This model supports mechanism capable of producing such shatter cone properties as orientation, apical clasts, lithic dependence, and shock pressure zonation. Although formational mechanics are still poorly understood, shatter cones have become the simplest geologic field criterion for recognizing astroblemes (ancient terrestrial impact structures).

  1. Methoxychlor inhibits growth of antral follicles by altering cell cycle regulators

    SciTech Connect

    Gupta, Rupesh K. Meachum, Sharon Hernandez-Ochoa, Isabel Peretz, Jackye Yao, Humphrey H. Flaws, Jodi A.

    2009-10-01

    Methoxychlor (MXC) reduces fertility in female rodents, decreases antral follicle numbers, and increases atresia through oxidative stress pathways. MXC also inhibits antral follicle growth in vitro. The mechanism by which MXC inhibits growth of follicles is unknown. The growth of follicles is controlled, in part, by cell cycle regulators. Thus, we tested the hypothesis that MXC inhibits follicle growth by reducing the levels of selected cell cycle regulators. Further, we tested whether co-treatment with an antioxidant, N-acetyl cysteine (NAC), prevents the MXC-induced reduction in cell cycle regulators. For in vivo studies, adult cycling CD-1 mice were dosed with MXC or vehicle for 20 days. Treated ovaries were subjected to immunohistochemistry for proliferating cell nuclear antigen (PCNA) staining. For in vitro studies, antral follicles isolated from adult cycling CD-1 mouse ovaries were cultured with vehicle, MXC, and/or NAC for 48, 72 and 96 h. Levels of cyclin D2 (Ccnd2) and cyclin dependent kinase 4 (Cdk4) were measured using in vivo and in vitro samples. The results indicate that MXC decreased PCNA staining, and Ccnd2 and Cdk4 levels compared to controls. NAC co-treatment restored follicle growth and expression of Ccnd2 and Cdk4. Collectively, these data indicate that MXC exposure reduces the levels of Ccnd2 and Cdk4 in follicles, and that protection from oxidative stress restores Ccnd2 and Cdk4 levels. Therefore, MXC-induced oxidative stress may decrease the levels of cell cycle regulators, which in turn, results in inhibition of the growth of antral follicles.

  2. Eupolyphaga sinensis walker displays inhibition on hepatocellular carcinoma through regulating cell growth and metastasis signaling.

    PubMed

    Zhang, Yanmin; Zhan, Yingzhuan; Zhang, Dongdong; Dai, Bingling; Ma, Weina; Qi, Junpeng; Liu, Rui; He, Langchong

    2014-01-01

    Tumor growth and metastasis are responsible for most cancer patients' deaths. Here, we report that eupolyphaga sinensis walker has an essential role in resisting hepatocellular carcinoma growth and metastasis. Compared with proliferation, colony formation, transwell assay and transplantable tumor in nude mouse in vitro and vivo, eupolyphaga sinensis walker extract (ESWE) showed good inhibition on the SMMC-7721 cell growth and metastasis. Using genome-wide microarray analysis, we found the down-regulated growth and metastasis factors, and selected down-regulated genes were confirmed by real-time PCR. Knockdown of a checkpoint PKCβ by siRNA significantly attenuated tumor inhibition and metastasis effects of ESWE. Moreover, our results indicate ESWE inhibits HCC growth by not only downregulating the signaling of PKCβ, Akt, m-TOR, Erk1/2, MEK-2, Raf and JNK-1, but also increasing cyclin D1 protein levels and decreasing amount of cyclin E, cyclin B1 and cdc2 of the cycle proteins. At the same time, ESWE reduced MMP2, MMP9 and CXCR4, PLG, NFκB and P53 activities. Overall, our studies demonstrate that ESWE is a key factor in growth and metastasis signaling inhibitor targeting the PKC, AKT, MAPK signaling and related metastasis signaling, having potential in cancer therapy. PMID:24980220

  3. Increase in neuropilin-1 on the surface of growth cones and putative raft domains in neuronal NG108-15 cells co-cultured with vascular smooth muscle SM-3 cells.

    PubMed

    Yoshimura, Ryoichi; Kyuka, Ayumi; Jinno, Miwa; Nishio, Satomi; Matsusaka, Mamoru; Nishida, Tomoki; Endo, Yasuhisa

    2015-04-01

    The mechanisms underlying autonomic innervation to its targets involve various chemical factors, but have not yet been elucidated in detail. We constructed a co-culture system of neuronal cells and vascular smooth muscle cells to investigate the mechanisms underlying innervation of the vasculature. A co-culture with the vascular smooth muscle cell line, SM-3 significantly promoted cell viability, neurite extension, and neuropilin-1 (Nrp-1) mRNA expression in the cholinergic neuronal cell line, NG108-15. Furthermore, immunocytochemistry with or without a detergent treatment revealed that a co-culture with SM-3 cells or culturing with the conditioned medium of SM-3 cells translocated Nrp-1 onto the cell surface of growth cones rather than varicosities of NG108-15 cells. Immunofluorescent microscopy combined with a cold detergent treatment or cholesterol depletion revealed that Nrp-1 accumulated in putative raft domains in the plasma membrane of NG108-15 cells co-cultured with SM-3 cells. The results of the present study suggest that some soluble factors from smooth muscle cells may affect the localization of Nrp-1 in cholinergic neuronal cells, which may, in turn, be involved in the autonomic innervation of blood vessels. PMID:25416424

  4. Soybean Homologs of MPK4 Negatively Regulate Defense Responses and Positively Regulate Growth and Development1[W][OA

    PubMed Central

    Liu, Jian-Zhong; Horstman, Heidi D.; Braun, Edward; Graham, Michelle A.; Zhang, Chunquan; Navarre, Duroy; Qiu, Wen-Li; Lee, Yeunsook; Nettleton, Dan; Hill, John H.; Whitham, Steven A.

    2011-01-01

    Mitogen-activated protein kinase (MAPK) cascades play important roles in disease resistance in model plant species such as Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana tabacum). However, the importance of MAPK signaling pathways in the disease resistance of crops is still largely uninvestigated. To better understand the role of MAPK signaling pathways in disease resistance in soybean (Glycine max), 13, nine, and 10 genes encoding distinct MAPKs, MAPKKs, and MAPKKKs, respectively, were silenced using virus-induced gene silencing mediated by Bean pod mottle virus. Among the plants silenced for various MAPKs, MAPKKs, and MAPKKKs, those in which GmMAPK4 homologs (GmMPK4s) were silenced displayed strong phenotypes including stunted stature and spontaneous cell death on the leaves and stems, the characteristic hallmarks of activated defense responses. Microarray analysis showed that genes involved in defense responses, such as those in salicylic acid (SA) signaling pathways, were significantly up-regulated in GmMPK4-silenced plants, whereas genes involved in growth and development, such as those in auxin signaling pathways and in cell cycle and proliferation, were significantly down-regulated. As expected, SA and hydrogen peroxide accumulation was significantly increased in GmMPK4-silenced plants. Accordingly, GmMPK4-silenced plants were more resistant to downy mildew and Soybean mosaic virus compared with vector control plants. Using bimolecular fluorescence complementation analysis and in vitro kinase assays, we determined that GmMKK1 and GmMKK2 might function upstream of GmMPK4. Taken together, our results indicate that GmMPK4s negatively regulate SA accumulation and defense response but positively regulate plant growth and development, and their functions are conserved across plant species. PMID:21878550

  5. Growth Control in Colon Epithelial Cells: Gadolinium Enhances Calcium-Mediated Growth Regulation

    PubMed Central

    Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K.

    2013-01-01

    Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1–5 µM combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet. PMID:23008064

  6. The Nuclear Receptor DAF-12 Regulates Nutrient Metabolism and Reproductive Growth in Nematodes

    PubMed Central

    Wang, Zhu; Stoltzfus, Jonathan; You, Young-jai; Ranjit, Najju; Tang, Hao; Xie, Yang; Lok, James B.; Mangelsdorf, David J.; Kliewer, Steven A.

    2015-01-01

    Appropriate nutrient response is essential for growth and reproduction. Under favorable nutrient conditions, the C. elegans nuclear receptor DAF-12 is activated by dafachronic acids, hormones that commit larvae to reproductive growth. Here, we report that in addition to its well-studied role in controlling developmental gene expression, the DAF-12 endocrine system governs expression of a gene network that stimulates the aerobic catabolism of fatty acids. Thus, activation of the DAF-12 transcriptome coordinately mobilizes energy stores to permit reproductive growth. DAF-12 regulation of this metabolic gene network is conserved in the human parasite, Strongyloides stercoralis, and inhibition of specific steps in this network blocks reproductive growth in both of the nematodes. Our study provides a molecular understanding for metabolic adaptation of nematodes to their environment, and suggests a new therapeutic strategy for treating parasitic diseases. PMID:25774872

  7. In situ growth of juvenile zebra mussels in a regulated stream

    USGS Publications Warehouse

    French, John R. P., III; Nichols, S. Jerrine; Craig, Jaquelyn M.; Allen, Jeffery D.; Black, M. Glen

    2006-01-01

    We investigated the in situ growth of juvenile zebra mussels (Dreissena polymorpha) in a reach of the Huron River (southeast Michigan) below a dam with a control gate that regulates water levels. Growth was significantly different among sample dates over a five-month-long monitoring season. Mean growth of mussels generally decreased from 0.093 mm/day just above the dam to 0.067 mm/day 4 km downstream, then increased to 0.091 mm/day at end of the 17-km-long study area. Significant differences among sites were most numerous in August during a severe drought when discharges fell substantially. Growth was positively correlated with discharges (R2 = 0.94, p a levels in the study area, however, was weak (R2 = 0.69, p < 0.1). Our study suggests that discharge may be one controlling factor for dreissenid populations in small streams.

  8. Rab8, POSH, and TAK1 regulate synaptic growth in a Drosophila model of frontotemporal dementia

    PubMed Central

    West, Ryan J.H.; Lu, Yubing; Marie, Bruno; Gao, Fen-Biao

    2015-01-01

    Mutations in genes essential for protein homeostasis have been identified in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) patients. Why mature neurons should be particularly sensitive to such perturbations is unclear. We identified mutations in Rab8 in a genetic screen for enhancement of an FTD phenotype associated with ESCRT-III dysfunction. Examination of Rab8 mutants or motor neurons expressing a mutant ESCRT-III subunit, CHMP2BIntron5, at the Drosophila melanogaster neuromuscular junction synapse revealed synaptic overgrowth and endosomal dysfunction. Expression of Rab8 rescued overgrowth phenotypes generated by CHMP2BIntron5. In Rab8 mutant synapses, c-Jun N-terminal kinase (JNK)/activator protein-1 and TGF-β signaling were overactivated and acted synergistically to potentiate synaptic growth. We identify novel roles for endosomal JNK-scaffold POSH (Plenty-of-SH3s) and a JNK kinase kinase, TAK1, in regulating growth activation in Rab8 mutants. Our data uncover Rab8, POSH, and TAK1 as regulators of synaptic growth responses and point to recycling endosome as a key compartment for synaptic growth regulation during neurodegenerative processes. PMID:25800055

  9. CYCD3 D-type cyclins regulate cambial cell proliferation and secondary growth in Arabidopsis

    PubMed Central

    Collins, Carl; Maruthi, N. M.; Jahn, Courtney E.

    2015-01-01

    A major proportion of plant biomass is derived from the activity of the cambium, a lateral meristem responsible for vascular tissue formation and radial organ enlargement in a process termed secondary growth. In contrast to our relatively good understanding of the regulation of primary meristems, remarkably little is known concerning the mechanisms controlling secondary growth, particularly how cambial cell divisions are regulated and integrated with vascular differentiation. A genetic loss-of-function approach was used here to reveal a rate-limiting role for the Arabidopsis CYCLIN D3 (CYCD3) subgroup of cell-cycle genes in the control of cambial cell proliferation and secondary growth, providing conclusive evidence of a direct link between the cell cycle and vascular development. It is shown that all three CYCD3 genes are specifically expressed in the cambium throughout vascular development. Analysis of a triple loss-of-function CYCD3 mutant revealed a requirement for CYCD3 in promoting the cambial cell cycle since mutant stems and hypocotyls showed a marked reduction in diameter linked to reduced mitotic activity in the cambium. Conversely, loss of CYCD3 provoked an increase in xylem cell size and the expression of differentiation markers, showing that CYCD3 is required to restrain the differentiation of xylem precursor cells. Together, our data show that tight control of cambial cell division through developmental- and cell type-specific regulation of CYCD3 is required for normal vascular development, constituting part of a novel mechanism controlling organ growth in higher plants. PMID:26022252

  10. The DUSP26 phosphatase activator adenylate kinase 2 regulates FADD phosphorylation and cell growth

    NASA Astrophysics Data System (ADS)

    Kim, Hyunjoo; Lee, Ho-June; Oh, Yumin; Choi, Seon-Guk; Hong, Se-Hoon; Kim, Hyo-Jin; Lee, Song-Yi; Choi, Ji-Woo; Su Hwang, Deog; Kim, Key-Sun; Kim, Hyo-Joon; Zhang, Jianke; Youn, Hyun-Jo; Noh, Dong-Young; Jung, Yong-Keun

    2014-02-01

    Adenylate kinase 2 (AK2), which balances adenine nucleotide pool, is a multi-functional protein. Here we show that AK2 negatively regulates tumour cell growth. AK2 forms a complex with dual-specificity phosphatase 26 (DUSP26) phosphatase and stimulates DUSP26 activity independently of its AK activity. AK2/DUSP26 phosphatase protein complex dephosphorylates fas-associated protein with death domain (FADD) and regulates cell growth. AK2 deficiency enhances cell proliferation and induces tumour formation in a xenograft assay. This anti-growth function of AK2 is associated with its DUSP26-stimulating activity. Downregulation of AK2 is frequently found in tumour cells and human cancer tissues showing high levels of phospho-FADDSer194. Moreover, reconstitution of AK2 in AK2-deficient tumour cells retards both cell proliferation and tumourigenesis. Consistent with this, AK2+/- mouse embryo fibroblasts exhibit enhanced cell proliferation with a significant alteration in phospho-FADDSer191. These results suggest that AK2 is an associated activator of DUSP26 and suppresses cell proliferation by FADD dephosphorylation, postulating AK2 as a negative regulator of tumour growth.

  11. In Pichia pastoris, growth rate regulates protein synthesis and secretion, mating and stress response

    PubMed Central

    Rebnegger, Corinna; Graf, Alexandra B; Valli, Minoska; Steiger, Matthias G; Gasser, Brigitte; Maurer, Michael; Mattanovich, Diethard

    2014-01-01

    Protein production in yeasts is related to the specific growth rate μ. To elucidate on this correlation, we studied the transcriptome of Pichia pastoris at different specific growth rates by cultivating a strain secreting human serum albumin at μ = 0.015 to 0.15 h–1 in glucose-limited chemostats. Genome-wide regulation revealed that translation-related as well as mitochondrial genes were upregulated with increasing μ, while autophagy and other proteolytic processes, carbon source-responsive genes and other targets of the TOR pathway as well as many transcriptional regulators were downregulated at higher μ. Mating and sporulation genes were most active at intermediate μ of 0.05 and 0.075 h–1. At very slow growth (μ = 0.015 h–1) gene regulation differs significantly, affecting many transporters and glucose sensing. Analysis of a subset of genes related to protein folding and secretion reveals that unfolded protein response targets such as translocation, endoplasmic reticulum genes, and cytosolic chaperones are upregulated with increasing growth rate while proteolytic degradation of secretory proteins is downregulated. We conclude that a high μ positively affects specific protein secretion rates by acting on multiple cellular processes. PMID:24323948

  12. Prioritizing plant defence over growth through WRKY regulation facilitates infestation by non-target herbivores

    PubMed Central

    Li, Ran; Zhang, Jin; Li, Jiancai; Zhou, Guoxin; Wang, Qi; Bian, Wenbo; Erb, Matthias; Lou, Yonggen

    2015-01-01

    Plants generally respond to herbivore attack by increasing resistance and decreasing growth. This prioritization is achieved through the regulation of phytohormonal signaling networks. However, it remains unknown how this prioritization affects resistance against non-target herbivores. In this study, we identify WRKY70 as a specific herbivore-induced, mitogen-activated protein kinase-regulated rice transcription factor that physically interacts with W-box motifs and prioritizes defence over growth by positively regulating jasmonic acid (JA) and negatively regulating gibberellin (GA) biosynthesis upon attack by the chewing herbivore Chilo suppressalis. WRKY70-dependent JA biosynthesis is required for proteinase inhibitor activation and resistance against C. suppressalis. In contrast, WRKY70 induction increases plant susceptibility against the rice brown planthopper Nilaparvata lugens. Experiments with GA-deficient rice lines identify WRKY70-dependent GA signaling as the causal factor in N. lugens susceptibility. Our study shows that prioritizing defence over growth leads to a significant resistance trade-off with important implications for the evolution and agricultural exploitation of plant immunity. DOI: http://dx.doi.org/10.7554/eLife.04805.001 PMID:26083713

  13. Merlin inhibits growth hormone-regulated Raf-ERKs pathways by binding to Grb2 protein

    SciTech Connect

    Lim, Jung Yeon; Kim, Hongtae; Jeun, Sin-Soo . E-mail: ssjeun@catholic.ac.kr; Kang, Seok-Gu; Lee, Kyung-Jin

    2006-02-24

    Numerous studies have suggested that the NF2 protein merlin is involved in the regulation of abnormal cell growth and proliferation. In this study, to better understand the merlin's mechanisms that contribute to the inhibition of tumorigenesis, we examined the potential action of merlin on the cell proliferative signaling pathways in response to growth hormone (GH). Merlin effectively attenuated the GH-induced serum response element (SRE) and Elk-1-mediated transcriptional activation, as well as the endogenous SRE-regulated gene c-fos expression in NIH3T3 cells. In addition, merlin prevented the Raf-1 complex activation process, which resulted in the suppression of MAP kinase/ERK, extracellular signal-regulated kinase (ERKs), and Elk-1 phosphorylation, which are the downstream signals of Raf-1. Moreover, it was shown that merlin interacted with endogenous growth factor receptor bound 2 (Grb2) protein and inhibited its expression. These results suggest that merlin contributes, via its protein-to-protein interaction with Grb2 and consequent inhibition of the MAPK pathways, to the regulation of the abnormal cell proliferation, and this provides a further mechanism underlying the tumor suppressor function of merlin.

  14. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters

    PubMed Central

    Ramesh, Sunita A.; Tyerman, Stephen D.; Xu, Bo; Bose, Jayakumar; Kaur, Satwinder; Conn, Vanessa; Domingos, Patricia; Ullah, Sana; Wege, Stefanie; Shabala, Sergey; Feijó, José A.; Ryan, Peter R.; Gillham, Matthew

    2015-01-01

    The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms. PMID:26219411

  15. EBP1 regulates organ size through cell growth and proliferation in plants

    PubMed Central

    Horváth, Beatrix M; Magyar, Zoltán; Zhang, Yuexing; Hamburger, Anne W; Bakó, László; Visser, Richard G F; Bachem, Christian W B; Bögre, László

    2006-01-01

    Plant organ size shows remarkable uniformity within species indicating strong endogenous control. We have identified a plant growth regulatory gene, functionally and structurally homologous to human EBP1. Plant EBP1 levels are tightly regulated; gene expression is highest in developing organs and correlates with genes involved in ribosome biogenesis and function. EBP1 protein is stabilised by auxin. Elevating or decreasing EBP1 levels in transgenic plants results in a dose-dependent increase or reduction in organ growth, respectively. During early stages of organ development, EBP1 promotes cell proliferation, influences cell-size threshold for division and shortens the period of meristematic activity. In postmitotic cells, it enhances cell expansion. EBP1 is required for expression of cell cycle genes; CyclinD3;1, ribonucleotide reductase 2 and the cyclin-dependent kinase B1;1. The regulation of these genes by EBP1 is dose and auxin dependent and might rely on the effect of EBP1 to reduce RBR1 protein level. We argue that EBP1 is a conserved, dose-dependent regulator of cell growth that is connected to meristematic competence and cell proliferation via regulation of RBR1 level. PMID:17024182

  16. PINK1 Is a Negative Regulator of Growth and the Warburg Effect in Glioblastoma.

    PubMed

    Agnihotri, Sameer; Golbourn, Brian; Huang, Xi; Remke, Marc; Younger, Susan; Cairns, Rob A; Chalil, Alan; Smith, Christian A; Krumholtz, Stacey-Lynn; Mackenzie, Danielle; Rakopoulos, Patricia; Ramaswamy, Vijay; Taccone, Michael S; Mischel, Paul S; Fuller, Gregory N; Hawkins, Cynthia; Stanford, William L; Taylor, Michael D; Zadeh, Gelareh; Rutka, James T

    2016-08-15

    Proliferating cancer cells are characterized by high rates of glycolysis, lactate production, and altered mitochondrial metabolism. This metabolic reprogramming provides important metabolites for proliferation of tumor cells, including glioblastoma. These biological processes, however, generate oxidative stress that must be balanced through detoxification of reactive oxygen species (ROS). Using an unbiased retroviral loss-of-function screen in nontransformed human astrocytes, we demonstrate that mitochondrial PTEN-induced kinase 1 (PINK1) is a regulator of the Warburg effect and negative regulator of glioblastoma growth. We report that loss of PINK1 contributes to the Warburg effect through ROS-dependent stabilization of hypoxia-inducible factor-1A and reduced pyruvate kinase muscle isozyme 2 activity, both key regulators of aerobic glycolysis. Mechanistically, PINK1 suppresses ROS and tumor growth through FOXO3a, a master regulator of oxidative stress and superoxide dismutase 2. These findings highlight the importance of PINK1 and ROS balance in normal and tumor cells. PINK1 loss was observed in a significant number of human brain tumors including glioblastoma (n > 900) and correlated with poor patient survival. PINK1 overexpression attenuates in vivo glioblastoma growth in orthotopic mouse xenograft models and a transgenic glioblastoma model in Drosophila Cancer Res; 76(16); 4708-19. ©2016 AACR. PMID:27325644

  17. Spectral Tuning of Deep Red Cone Pigments†

    PubMed Central

    Amora, Tabitha L.; Ramos, Lavoisier S.; Galan, Jhenny F.; Birge, Robert R.

    2008-01-01

    Visual pigments are G-protein-coupled receptors that provide a critical interface between organisms and their external environment. Natural selection has generated vertebrate pigments that absorb light from the far-UV (360 nm) to the deep red (630 nm) while using a single chromophore, in either the A1 (11-cis-retinal) or A2 (11-cis-3,4-dehydroretinal) form. The fact that a single chromophore can be manipulated to have an absorption maximum across such an extended spectral region is remarkable. The mechanisms of wavelength regulation remain to be fully revealed, and one of the least well-understood mechanisms is that associated with the deep red pigments. We investigate theoretically the hypothesis that deep red cone pigments select a 6-s-trans conformation of the retinal chromophore ring geometry. This conformation is in contrast to the 6-s-cis ring geometry observed in rhodopsin and, through model chromophore studies, the vast majority of visual pigments. Nomographic spectral analysis of 294 A1 and A2 cone pigment literature absorption maxima indicates that the selection of a 6-s-trans geometry red shifts M/LWS A1 pigments by ~1500 cm−1 (~50 nm) and A2 pigments by ~2700 cm−1 (~100 nm). The homology models of seven cone pigments indicate that the deep red cone pigments select 6-s-trans chromophore conformations primarily via electrostatic steering. Our results reveal that the generation of a 6-s-trans conformation not only achieves a significant red shift but also provides enhanced stability of the chromophore within the deep red cone pigment binding sites. PMID:18370404

  18. Drosophila Spidey/Kar Regulates Oenocyte Growth via PI3-Kinase Signaling

    PubMed Central

    Cinnamon, Einat; Sawala, Annick; Tittiger, Claus; Paroush, Ze'ev

    2016-01-01

    Cell growth and proliferation depend upon many different aspects of lipid metabolism. One key signaling pathway that is utilized in many different anabolic contexts involves Phosphatidylinositide 3-kinase (PI3K) and its membrane lipid products, the Phosphatidylinositol (3,4,5)-trisphosphates. It remains unclear, however, which other branches of lipid metabolism interact with the PI3K signaling pathway. Here, we focus on specialized fat metabolizing cells in Drosophila called larval oenocytes. In the presence of dietary nutrients, oenocytes undergo PI3K-dependent cell growth and contain very few lipid droplets. In contrast, during starvation, oenocytes decrease PI3K signaling, shut down cell growth and accumulate abundant lipid droplets. We now show that PI3K in larval oenocytes, but not in fat body cells, functions to suppress lipid droplet accumulation. Several enzymes of fatty acid, triglyceride and hydrocarbon metabolism are required in oenocytes primarily for lipid droplet induction rather than for cell growth. In contrast, a very long chain fatty-acyl-CoA reductase (FarO) and a putative lipid dehydrogenase/reductase (Spidey, also known as Kar) not only promote lipid droplet induction but also inhibit oenocyte growth. In the case of Spidey/Kar, we show that the growth suppression mechanism involves inhibition of the PI3K signaling pathway upstream of Akt activity. Together, the findings in this study show how Spidey/Kar and FarO regulate the balance between the cell growth and lipid storage of larval oenocytes. PMID:27500738

  19. Drosophila Spidey/Kar Regulates Oenocyte Growth via PI3-Kinase Signaling.

    PubMed

    Cinnamon, Einat; Makki, Rami; Sawala, Annick; Wickenberg, Leah P; Blomquist, Gary J; Tittiger, Claus; Paroush, Ze'ev; Gould, Alex P

    2016-08-01

    Cell growth and proliferation depend upon many different aspects of lipid metabolism. One key signaling pathway that is utilized in many different anabolic contexts involves Phosphatidylinositide 3-kinase (PI3K) and its membrane lipid products, the Phosphatidylinositol (3,4,5)-trisphosphates. It remains unclear, however, which other branches of lipid metabolism interact with the PI3K signaling pathway. Here, we focus on specialized fat metabolizing cells in Drosophila called larval oenocytes. In the presence of dietary nutrients, oenocytes undergo PI3K-dependent cell growth and contain very few lipid droplets. In contrast, during starvation, oenocytes decrease PI3K signaling, shut down cell growth and accumulate abundant lipid droplets. We now show that PI3K in larval oenocytes, but not in fat body cells, functions to suppress lipid droplet accumulation. Several enzymes of fatty acid, triglyceride and hydrocarbon metabolism are required in oenocytes primarily for lipid droplet induction rather than for cell growth. In contrast, a very long chain fatty-acyl-CoA reductase (FarO) and a putative lipid dehydrogenase/reductase (Spidey, also known as Kar) not only promote lipid droplet induction but also inhibit oenocyte growth. In the case of Spidey/Kar, we show that the growth suppression mechanism involves inhibition of the PI3K signaling pathway upstream of Akt activity. Together, the findings in this study show how Spidey/Kar and FarO regulate the balance between the cell growth and lipid storage of larval oenocytes. PMID:27500738

  20. Fatty acid regulates gene expression and growth of human prostate cancer PC-3 cells

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.; Chen, Y.; Tjandrawinata, R. R.

    2001-01-01

    It has been proposed that the omega-6 fatty acids increase the rate of tumor growth. Here we test that hypothesis in the PC-3 human prostate tumor. We found that the essential fatty acids, linoleic acid (LA) and arachidonic acid (AA), and the AA metabolite PGE(2) stimulate tumor growth while oleic acid (OA) and the omega-3 fatty acid, eicosapentaenoic acid (EPA) inhibited growth. In examining the role of AA in growth response, we extended our studies to analyze changes in early gene expression induced by AA. We demonstrate that c-fos expression is increased within minutes of addition in a dose-dependent manner. Moreover, the immediate early gene cox-2 is also increased in the presence of AA in a dose-dependent manner, while the constitutive cox-1 message was not increased. Three hours after exposure to AA, the synthesis of PGE(2) via COX-2 was also increased. Previous studies have demonstrated that AA was primarily delivered by low density lipoprotein (LDL) via its receptor (LDLr). Since it is known that hepatomas, acute myelogenous leukemia and colorectal tumors lack normal cholesterol feedback, we examined the role of the LDLr in growth regulation of the PC-3 prostate cancer cells. Analysis of ldlr mRNA expression and LDLr function demonstrated that human PC-3 prostate cancer cells lack normal feedback regulation. While exogenous LDL caused a significant stimulation of cell growth and PGE(2) synthesis, no change was seen in regulation of the LDLr by LDL. Taken together, these data show that normal cholesterol feedback of ldlr message and protein is lost in prostate cancer. These data suggest that unregulated over-expression of LDLr in tumor cells would permit increased availability of AA, which induces immediate early genes c-fos and cox-2 within minutes of uptake.

  1. Regulation of cell surface receptors for different hematopoietic growth factors on myeloid leukemic cells.

    PubMed Central

    Lotem, J; Sachs, L

    1986-01-01

    There are clones of myeloid leukemic cells which are different from normal myeloid cells in that they have become independent of hematopoietic growth factor for cell viability and growth. The ability of these clones to bind three types of hematopoietic growth factors (MGI-1GM = GM-CSF, IL-3 = multi-CSF and MGI-1M = M-CSF = CSF-1) was measured using the method of quantitative absorption at 1 degree C and low pH elution of cell-bound biological activity. Results of binding to normal myeloid and lymphoid cells were similar to those obtained by radioreceptor assays. The results indicate that the number of receptors on different clones of these leukemic cells varied from 0 to 1,300 per cell. The receptors have a high binding affinity. Receptors for different growth factors can be independently expressed in different clones. There was no relationship between expression of receptors for these growth factors and the phenotype of the leukemic cells regarding their ability to be induced to differentiate. The number of receptors on the leukemic cells was lower than on normal mature macrophages. Myeloid leukemic cells induced to differentiate by normal myeloid cell differentiation factor MGI-2 (= DF), or by low doses of actinomycin D or cytosine arabinoside, showed an up-regulation of the number of MGI-1GM and IL-3 receptors. Induction of differentiation of leukemic cells by MGI-2 also induced production and secretion of the growth factor MGI-1GM, and this induced MGI-1GM saturated the up-regulated MGI-1GM receptors. It is suggested that up-regulation of these receptors during differentiation is required for the functioning of differentiated cells. PMID:3023059

  2. Nutrition regulation of male accessory gland growth and maturation in Tribolium castaneum.

    PubMed

    Xu, Jingjing; Anciro, Ashlee L; Palli, Subba Reddy

    2015-01-01

    Insulin/IGF-1 signaling (IIS) pathway is known to control growth, development and reproduction. Insulin-like peptide mediated body size plasticity in Drosophila melanogaster has been reported. Here, our studies showed that IIS pathway and nutrition regulate growth and maturation of the male accessory gland (MAG) in the red flour beetle, Tribolium castaneum. The size of MAG increased from day 1 to day 5 post-adult emergence (PAE). This increase in the size of MAG is contributed by an increase in cell size, but not cell number. The growth of MAG was impaired after double-stranded RNA (dsRNA)-mediated knockdown in the expression of genes coding for ILP3, InR, Chico, PI3k, AKT, and GATA1 involved in IIS pathway. Interestingly, starvation showed similar effects on the growth and maturation of MAG. The phenotypes observed in animals where IIS signaling pathway genes were knocked down are similar to the phenotypes observed after starving beetles for 5 days PAE. These data suggest that nutrition signals working through IIS pathway regulate maturation of MAG by promoting the growth of MAG cells. PMID:26035685

  3. Fatty acid esters produced by Lasiodiplodia theobromae function as growth regulators in tobacco seedlings.

    PubMed

    Uranga, Carla C; Beld, Joris; Mrse, Anthony; Córdova-Guerrero, Iván; Burkart, Michael D; Hernández-Martínez, Rufina

    2016-04-01

    The Botryosphaeriaceae are a family of trunk disease fungi that cause dieback and death of various plant hosts. This work sought to characterize fatty acid derivatives in a highly virulent member of this family, Lasiodiplodia theobromae. Nuclear magnetic resonance and gas chromatography-mass spectrometry of an isolated compound revealed (Z, Z)-9,12-ethyl octadecadienoate, (trivial name ethyl linoleate), as one of the most abundant fatty acid esters produced by L. theobromae. A variety of naturally produced esters of fatty acids were identified in Botryosphaeriaceae. In comparison, the production of fatty acid esters in the soil-borne tomato pathogen Fusarium oxysporum, and the non-phytopathogenic fungus Trichoderma asperellum was found to be limited. Ethyl linoleate, ethyl hexadecanoate (trivial name ethyl palmitate), and ethyl octadecanoate, (trivial name ethyl stearate), significantly inhibited tobacco seed germination and altered seedling leaf growth patterns and morphology at the highest concentration (0.2 mg/mL) tested, while ethyl linoleate and ethyl stearate significantly enhanced growth at low concentrations, with both still inducing growth at 98 ng/mL. This work provides new insights into the role of naturally esterified fatty acids from L. theobromae as plant growth regulators with similar activity to the well-known plant growth regulator gibberellic acid. PMID:26926564

  4. Regulation of body mass growth through activin type IIB receptor in teleost fish.

    PubMed

    Carpio, Yamila; Acosta, Jannel; Morales, Reynold; Santisteban, Yaimín; Sanchéz, Aniel; Estrada, Mario Pablo

    2009-01-15

    Myostatin is a TGF-beta family member that plays a key role in regulating skeletal muscle growth. Previous studies in mammals have demonstrated that myostatin is capable of binding the two activin type II receptors. Additionally, activin type II receptors have been shown to be capable of binding a number of other TGF-beta family members besides myostatin. An injection of a soluble form of activin type IIB receptor obtained from CHO cells into wild-type mice generated up to a 60% increase in muscle mass in 2 weeks. The knowledge on the role of activin receptors in fish is limited. In the present study, we examined the growth effect of administering a recombinant, soluble form of goldfish activin type IIB receptor extracellular domain to juvenile and larval goldfish (Carassius auratus), African catfish (Clarias gariepinus) larvae and tilapia (Oreochromis aureus) larvae. We have expressed the goldfish activin type IIB receptor extracellular domain in the yeast Pichia pastoris and we have demonstrated for the first time that this recombinant molecule stimulates growth in teleost fish in a dose-dependent manner. We provide evidence that this body weight increase is achieved by an increase in muscle mass and protein content. Histological analysis of the goldfish muscle revealed that treated fish exhibited hyperplasia as compared to controls. These findings contribute to the understanding of the mechanisms that regulate growth in non-mammalian vertebrates and suggest a powerful biotechnology approach to improving fish growth in aquaculture. PMID:19056390

  5. Inverse regulation of human ERBB2 and epidermal growth factor receptors by tumor necrosis factor alpha.

    PubMed Central

    Kalthoff, H; Roeder, C; Gieseking, J; Humburg, I; Schmiegel, W

    1993-01-01

    Recombinant human tumor necrosis factor (TNF) alpha decreased the expression of ERBB2 mRNA by stimulating p55 TNF receptors of pancreatic tumor cells. This decrease contrasts with an increase in epidermal growth factor receptor (EGFR) mRNA. Both effects were selectively achieved by TNF-alpha or -beta, whereas interferon alpha or gamma or transforming growth factor beta showed no such effects. The inverse regulatory effects of TNF on ERBB2 and EGFR mRNA levels were evoked by different signaling pathways of p55 TNF receptors. The TNF-mediated ERBB2 mRNA decrease was followed by a reduction in protein. Four of five pancreatic tumor cell lines exhibited this down-regulation. This decrease of ERBB2 is a singular example of a modulation of this growth factor receptor by TNF. Overexpression of ERBB2 has been reported to cause resistance to TNF and other cytotoxic cytokines. In our study we show that the TNF-mediated down-regulation of ERBB2 in pancreatic tumor cells is accompanied by an increase in growth inhibition at low doses of TNF. The simultaneous alteration of the ERBB2/EGFR balance by TNF represents a striking model of cytokine receptor transregulation in the growth control of malignant pancreatic epithelial cells. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8105469

  6. Arctiin induces cell growth inhibition through the down-regulation of cyclin D1 expression.

    PubMed

    Matsuzaki, Youichirou; Koyama, Makoto; Hitomi, Toshiaki; Yokota, Tomoya; Kawanaka, Mayumi; Nishikawa, Akiyoshi; Germain, Doris; Sakai, Toshiyuki

    2008-03-01

    Arctiin is a major lignan constituent of Arctium lappa and has anti-cancer properties in animal models. It was recently reported that arctiin induces growth inhibition in human prostate cancer PC-3 cells. However, the growth inhibitory mechanism of arctiin remains unknown. Herein we report that arctiin induces growth inhibition and dephosphorylates the tumor-suppressor retinoblastoma protein in human immortalized keratinocyte HaCaT cells. We also show that the growth inhibition caused by arctiin is associated with the down-regulation of cyclin D1 protein expression. Furthermore, the arctiin-induced suppression of cyclin D1 protein expression occurs in various types of human tumor cells, including osteosarcoma, lung, colorectal, cervical and breast cancer, melanoma, transformed renal cells and prostate cancer. Depletion of the cyclin D1 protein using small interfering RNA-rendered human breast cancer MCF-7 cells insensitive to the growth inhibitory effects of arctiin, implicates cyclin D1 as an important target of arctiin. Taken together, these results suggest that arctiin down-regulates cyclin D1 protein expression and that this at least partially contributes to the anti-proliferative effect of arctiin. PMID:18288407

  7. Phytohormone regulation of root growth triggered by P deficiency or Al toxicity.

    PubMed

    Sun, Lili; Tian, Jiang; Zhang, Haiyan; Liao, Hong

    2016-06-01

    Phosphorus (P) deficiency and aluminum (Al) toxicity often coexist and limit plant growth on acid soils. It has been well documented that both P deficiency and Al toxicity alter root growth, including inhibition of primary roots and promotion of lateral roots. This suggests that plants adapt to both stresses through a common regulation pathway. Although an expanding set of results shows that phytohormones play vital roles in controlling root responses to Pi starvation and Al toxicity, it remains largely unknown whether P and Al coordinately regulate root growth through interacting phytohormone biosynthesis and signal transduction pathways. This review provides a summary of recent results concerning the influences of P deficiency and Al toxicity on root growth through the action of phytohormones, most notably auxin and ethylene. The objective is to facilitate increasing insights into complex responses of plants to adverse factors common on acid soils, which can spur development of 'smart' cultivars with better root growth and higher yield on these globally distributed marginal soils. PMID:27190050

  8. Growth and the regulation of myotomal muscle mass in teleost fish.

    PubMed

    Johnston, Ian A; Bower, Neil I; Macqueen, Daniel J

    2011-05-15

    Teleost muscle first arises in early embryonic life and its development is driven by molecules present in the egg yolk and modulated by environmental stimuli including temperature and oxygen. Several populations of myogenic precursor cells reside in the embryonic somite and external cell layer and contribute to muscle fibres in embryo, larval, juvenile and adult stages. Many signalling proteins and transcription factors essential for these events are known. In all cases, myogenesis involves myoblast proliferation, migration, fusion and terminal differentiation. Maturation of the embryonic muscle is associated with motor innervation and the development of a scaffold of connective tissue and complex myotomal architecture needed to generate swimming behaviour. Adult muscle is a heterogeneous tissue composed of several cell types that interact to affect growth patterns. The development of capillary and lymphatic circulations and extramuscular organs--notably the gastrointestinal, endocrine, neuroendocrine and immune systems--serves to increase information exchange between tissues and with the external environment, adding to the complexity of growth regulation. Teleosts often exhibit an indeterminate growth pattern, with body size and muscle mass increasing until mortality or senescence occurs. The dramatic increase in myotomal muscle mass between embryo and adult requires the continuous production of muscle fibres until 40-50% of the maximum body length is reached. Sarcomeric proteins can be mobilised as a source of amino acids for energy metabolism by other tissues and for gonad generation, requiring the dynamic regulation of muscle mass throughout the life cycle. The metabolic and contractile phenotypes of muscle fibres also show significant plasticity with respect to environmental conditions, migration and spawning. Many genes regulating muscle growth are found as multiple copies as a result of paralogue retention following whole-genome duplication events in teleost

  9. Overview of OVATE FAMILY PROTEINS, A Novel Class of Plant-Specific Growth Regulators.

    PubMed

    Wang, Shucai; Chang, Ying; Ellis, Brian

    2016-01-01

    OVATE FAMILY PROTEINS (OFPs) are a class of proteins with a conserved OVATE domain. OVATE protein was first identified in tomato as a key regulator of fruit shape. OFPs are plant-specific proteins that are widely distributed in the plant kingdom including mosses and lycophytes. Transcriptional activity analysis of Arabidopsis OFPs (AtOFPs) in protoplasts suggests that they act as transcription repressors. Functional characterization of OFPs from different plant species including Arabidopsis, rice, tomato, pepper, and banana suggests that OFPs regulate multiple aspects of plant growth and development, which is likely achieved by interacting with different types of transcription factors including the KNOX and BELL classes, and/or directly regulating the expression of target genes such as Gibberellin 20 oxidase (GA20ox). Here, we examine how OVATE was originally identified, summarize recent progress in elucidation of the roles of OFPs in regulating plant growth and development, and describe possible mechanisms underpinning this regulation. Finally, we review potential new research directions that could shed additional light on the functional biology of OFPs in plants. PMID:27065353

  10. Overview of OVATE FAMILY PROTEINS, A Novel Class of Plant-Specific Growth Regulators

    PubMed Central

    Wang, Shucai; Chang, Ying; Ellis, Brian

    2016-01-01

    OVATE FAMILY PROTEINS (OFPs) are a class of proteins with a conserved OVATE domain. OVATE protein was first identified in tomato as a key regulator of fruit shape. OFPs are plant-specific proteins that are widely distributed in the plant kingdom including mosses and lycophytes. Transcriptional activity analysis of Arabidopsis OFPs (AtOFPs) in protoplasts suggests that they act as transcription repressors. Functional characterization of OFPs from different plant species including Arabidopsis, rice, tomato, pepper, and banana suggests that OFPs regulate multiple aspects of plant growth and development, which is likely achieved by interacting with different types of transcription factors including the KNOX and BELL classes, and/or directly regulating the expression of target genes such as Gibberellin 20 oxidase (GA20ox). Here, we examine how OVATE was originally identified, summarize recent progress in elucidation of the roles of OFPs in regulating plant growth and development, and describe possible mechanisms underpinning this regulation. Finally, we review potential new research directions that could shed additional light on the functional biology of OFPs in plants. PMID:27065353

  11. Enhanced light trapping in periodically truncated cone silicon nanowire structure

    NASA Astrophysics Data System (ADS)

    Kai, Qiu; Yuhua, Zuo; Tianwei, Zhou; Zhi, Liu; Jun, Zheng; Chuanbo, Li; Buwen, Cheng

    2015-10-01

    Light trapping plays an important role in improving the conversion efficiency of thin-film solar cells. The good wideband light trapping is achieved using our periodically truncated cone Si nanowire (NW) structures, and their inherent mechanism is analyzed and simulated by FDTD solution software. Ordered cylinder Si NW structure with initial size of 80 nm and length of 200 nm is grown by pattern transfer and selective epitaxial growth. Truncated cone Si NW array is then obtained by thermal oxidation treatment. Its mean reflection in the range of 300-900 nm is lowered to be 5% using 140 nm long truncated cone Si NW structure, compared with that of 20% using cylinder counterparts. It indicates that periodically truncated Si cone structures trap the light efficiently to enhance the light harvesting in a wide spectral range and have the potential application in highly efficient NW solar cells. Project supported by the National Natural Science Foundation of China (Nos. 51072194, 61021003, 61036001, 61376057).

  12. Loss-cone-driven ion cyclotron waves in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Denton, Richard E.; Hudson, Mary K.; Roth, Ilan

    1992-01-01

    The study examines the theoretical properties of linear ion cyclotron waves propagating in the magnetosphere at arbitrary angles to the background magnetic field. It is found that in some cases the linear wave growth of modes with oblique propagation can dominate that of the parallel propagating electromagnetic ion cyclotron (EMIC) wave. The growth rate of the loss-cone-driven mode depends strongly on the depth of the loss cone. A simple analytical theory which explains the scaling of the growth rate of the oblique mode with respect to various parameters is presented. The loss-cone-driven mode is an electromagnetic mode which is preferentially nearly linearly polarized. The wave field which results from the oblique mode in its perferentially nearly linearly polarized form are nearly perpendicular to B0 and are such that they may be difficult to distinguish from those of a linearly polarized parallel propgating EMIC wave.

  13. Exogenously Applied Plant Growth Regulators Enhance the Morpho-Physiological Growth and Yield of Rice under High Temperature.

    PubMed

    Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Ihsan, Zahid; Shah, Adnan N; Wu, Chao; Yousaf, Muhammad; Nasim, Wajid; Alharby, Hesham; Alghabari, Fahad; Huang, Jianliang

    2016-01-01

    A 2-year experiment was conducted to ascertain the effects of exogenously applied plant growth regulators (PGR) on rice growth and yield attributes under high day (HDT) and high night temperature (HNT). Two rice cultivars (IR-64 and Huanghuazhan) were subjected to temperature treatments in controlled growth chambers and four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA), and triazoles (Tr) were applied. High temperature severely affected rice morphology, and also reduced leaf area, above-, and below-ground biomass, photosynthesis, and water use efficiency, while increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more detrimental for grain formation and yield. The Huanghuazhan performed better than IR-64 under high temperature stress with better growth and higher grain yield. Exogenous application of PGRs was helpful in alleviating the adverse effects of high temperature. Among PGR combinations, the Vc+Ve+MejA+Br was the most effective treatment for both cultivars under high temperature stress. The highest grain production by Vc+Ve+MejA+Br treated plants was due to enhanced photosynthesis, spikelet fertility and grain filling, which compensated the adversities of high temperature stress. Taken together, these results will be of worth for further understanding the adaptation and survival mechanisms of rice to high temperature and will assist in developing heat-resistant rice germplasm in future. PMID:27625658

  14. Exogenously Applied Plant Growth Regulators Enhance the Morpho-Physiological Growth and Yield of Rice under High Temperature

    PubMed Central

    Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Ihsan, Zahid; Shah, Adnan N.; Wu, Chao; Yousaf, Muhammad; Nasim, Wajid; Alharby, Hesham; Alghabari, Fahad; Huang, Jianliang

    2016-01-01

    A 2-year experiment was conducted to ascertain the effects of exogenously applied plant growth regulators (PGR) on rice growth and yield attributes under high day (HDT) and high night temperature (HNT). Two rice cultivars (IR-64 and Huanghuazhan) were subjected to temperature treatments in controlled growth chambers and four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA), and triazoles (Tr) were applied. High temperature severely affected rice morphology, and also reduced leaf area, above-, and below-ground biomass, photosynthesis, and water use efficiency, while increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more detrimental for grain formation and yield. The Huanghuazhan performed better than IR-64 under high temperature stress with better growth and higher grain yield. Exogenous application of PGRs was helpful in alleviating the adverse effects of high temperature. Among PGR combinations, the Vc+Ve+MejA+Br was the most effective treatment for both cultivars under high temperature stress. The highest grain production by Vc+Ve+MejA+Br treated plants was due to enhanced photosynthesis, spikelet fertility and grain filling, which compensated the adversities of high temperature stress. Taken together, these results will be of worth for further understanding the adaptation and survival mechanisms of rice to high temperature and will assist in developing heat-resistant rice germplasm in future. PMID:27625658

  15. [Transforming growth factor beta-1: structure, function, and regulation mechanisms in cancer].

    PubMed

    Peralta-Zaragoza, O; Lagunas-Martínez, A; Madrid-Marina, V

    2001-01-01

    Transforming growth factor beta-1 (TGF-beta 1) is produced by several cell lineages such as lymphocytes, macrophages, and dendritic cells, and its expression serves in both autocrine and paracrine modes to control the differentiation, proliferation, and state of activation of these and other cells. In general, TGF-beta 1 has pleiotropic properties on the immune response during the development of infection diseases and cancer; however, the mechanisms of action and regulation of gene expression of this cytokine are poorly understood, in this review, the biological properties and the molecular mechanisms that regulate TGF-beta 1 gene expression are described, to understand the role of this cytokine in growth and cell differentiation. The knowledge of molecular mechanisms of gene expression of TGF-beta 1 may serve to develop new cancer therapies. The English version of this paper is available at: http://www.insp.mx/salud/index.html PMID:11547595

  16. Cone on Olympus Mons

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03078 Cone on Olympus Mons

    This image shows just a small part of the eastern flank of Olympus Mons. On the far left side of the image a small volcanic cone can be seen. The shadow helps to identify this feature.

    Image information: VIS instrument. Latitude 15.7N, Longitude 229.7E. 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  17. The Holographic Entropy Cone

    SciTech Connect

    Bao, Ning; Nezami, Sepehr; Ooguri, Hirosi; Stoica, Bogdan; Sully, James; Walter, Michael

    2015-09-21

    We initiate a systematic enumeration and classification of entropy inequalities satisfied by the Ryu-Takayanagi formula for conformal field theory states with smooth holographic dual geometries. For 2, 3, and 4 regions, we prove that the strong subadditivity and the monogamy of mutual information give the complete set of inequalities. This is in contrast to the situation for generic quantum systems, where a complete set of entropy inequalities is not known for 4 or more regions. We also find an infinite new family of inequalities applicable to 5 or more regions. The set of all holographic entropy inequalities bounds the phase space of Ryu-Takayanagi entropies, defining the holographic entropy cone. We characterize this entropy cone by reducing geometries to minimal graph models that encode the possible cutting and gluing relations of minimal surfaces. We find that, for a fixed number of regions, there are only finitely many independent entropy inequalities. To establish new holographic entropy inequalities, we introduce a combinatorial proof technique that may also be of independent interest in Riemannian geometry and graph theory.

  18. The Holographic Entropy Cone

    DOE PAGESBeta

    Bao, Ning; Nezami, Sepehr; Ooguri, Hirosi; Stoica, Bogdan; Sully, James; Walter, Michael

    2015-09-21

    We initiate a systematic enumeration and classification of entropy inequalities satisfied by the Ryu-Takayanagi formula for conformal field theory states with smooth holographic dual geometries. For 2, 3, and 4 regions, we prove that the strong subadditivity and the monogamy of mutual information give the complete set of inequalities. This is in contrast to the situation for generic quantum systems, where a complete set of entropy inequalities is not known for 4 or more regions. We also find an infinite new family of inequalities applicable to 5 or more regions. The set of all holographic entropy inequalities bounds the phasemore » space of Ryu-Takayanagi entropies, defining the holographic entropy cone. We characterize this entropy cone by reducing geometries to minimal graph models that encode the possible cutting and gluing relations of minimal surfaces. We find that, for a fixed number of regions, there are only finitely many independent entropy inequalities. To establish new holographic entropy inequalities, we introduce a combinatorial proof technique that may also be of independent interest in Riemannian geometry and graph theory.« less

  19. The holographic entropy cone

    NASA Astrophysics Data System (ADS)

    Bao, Ning; Nezami, Sepehr; Ooguri, Hirosi; Stoica, Bogdan; Sully, James; Walter, Michael

    2015-09-01

    We initiate a systematic enumeration and classification of entropy inequalities satisfied by the Ryu-Takayanagi formula for conformal field theory states with smooth holographic dual geometries. For 2, 3, and 4 regions, we prove that the strong subadditivity and the monogamy of mutual information give the complete set of inequalities. This is in contrast to the situation for generic quantum systems, where a complete set of entropy inequalities is not known for 4 or more regions. We also find an infinite new family of inequalities applicable to 5 or more regions. The set of all holographic entropy inequalities bounds the phase space of Ryu-Takayanagi entropies, defining the holographic entropy cone. We characterize this entropy cone by reducing geometries to minimal graph models that encode the possible cutting and gluing relations of minimal surfaces. We find that, for a fixed number of regions, there are only finitely many independent entropy inequalities. To establish new holographic entropy inequalities, we introduce a combinatorial proof technique that may also be of independent interest in Riemannian geometry and graph theory.

  20. The Mycobacterium tuberculosis H37Ra gene MRA_1916 causes growth defects upon down-regulation.

    PubMed

    Singh, Kumar Sachin; Singh, Sudheer Kumar

    2015-01-01

    D-amino acid oxidases play an important role in converting D-amino acids to their corresponding α-keto acids. MRA_1916 of Mycobacterium tuberculosis H37Ra (Mtb-Ra) is annotated to be a D-amino acid oxidase (DAO). However, not much information is available about its physiological role during Mtb-Ra growth and survival. The present study was taken-up to understand the role of DAO during different stages of growth and effect of its down-regulation on growth. Recombinant Mtb-Ra strains with DAO and GlcB (malate synthase: MRA_1848) gene knockdown were developed and their growth was studied using Microtiter Alamar Blue Assay (MABA) with glycerol, acetate and glycine as a carbon source. Ethyl bromopyruvate (BrP) was used as an inhibitor of GlcB. MABA study showed inhibition of wild-type (WT) and knockdowns in the presence of BrP (2.5mM). However, growth inhibition of WT was less noticeable at lower concentrations of BrP. Mtb-Ra with DAO knockdown showed poor utilization of glycine in the presence of BrP. The DAO localization study showed its prominent distribution in cytosolic fraction and to some extent in cell wall and membrane fractions. Growth profile of WT under oxygen and nutritional stress showed changes in expression of DAO, GlcB, PckA (phosphoenolpyruvate carboxykinase: MRA_0219) and GlyA1 (serine hydroxymethyltransferase: MRA_1104). PMID:26531045

  1. The Mycobacterium tuberculosis H37Ra gene MRA_1916 causes growth defects upon down-regulation

    PubMed Central

    Singh, Kumar Sachin; Singh, Sudheer Kumar

    2015-01-01

    D-amino acid oxidases play an important role in converting D-amino acids to their corresponding α-keto acids. MRA_1916 of Mycobacterium tuberculosis H37Ra (Mtb-Ra) is annotated to be a D-amino acid oxidase (DAO). However, not much information is available about its physiological role during Mtb-Ra growth and survival. The present study was taken-up to understand the role of DAO during different stages of growth and effect of its down-regulation on growth. Recombinant Mtb-Ra strains with DAO and GlcB (malate synthase: MRA_1848) gene knockdown were developed and their growth was studied using Microtiter Alamar Blue Assay (MABA) with glycerol, acetate and glycine as a carbon source. Ethyl bromopyruvate (BrP) was used as an inhibitor of GlcB. MABA study showed inhibition of wild-type (WT) and knockdowns in the presence of BrP (2.5mM). However, growth inhibition of WT was less noticeable at lower concentrations of BrP. Mtb-Ra with DAO knockdown showed poor utilization of glycine in the presence of BrP. The DAO localization study showed its prominent distribution in cytosolic fraction and to some extent in cell wall and membrane fractions. Growth profile of WT under oxygen and nutritional stress showed changes in expression of DAO, GlcB, PckA (phosphoenolpyruvate carboxykinase: MRA_0219) and GlyA1 (serine hydroxymethyltransferase: MRA_1104). PMID:26531045

  2. Human mitochondrial transcription factor A functions in both nuclei and mitochondria and regulates cancer cell growth

    SciTech Connect

    Han, Bin; Izumi, Hiroto; Yasuniwa, Yoshihiro; Akiyama, Masaki; Yamaguchi, Takahiro; Fujimoto, Naohiro; Matsumoto, Tetsuro; Wu, Bin; Tanimoto, Akihide; Sasaguri, Yasuyuki; Kohno, Kimitoshi

    2011-04-29

    Highlights: {yields} Mitochondrial transcription factor A (mtTFA) localizes in nuclei and binds tightly to the nuclear chromatin. {yields} mtTFA contains two putative nuclear localization signals (NLS) in the HMG-boxes. {yields} Overexpression of mtTFA enhances the growth of cancer cells, whereas downregulation of mtTFA inhibits their growth by regulating mtTFA target genes, such as baculoviral IAP repeat-containing 5 (BIRC5; also known as survivin). {yields} Knockdown of mtTFA expression induces p21-dependent G1 cell cycle arrest. -- Abstract: Mitochondrial transcription factor A (mtTFA) is one of the high mobility group protein family and is required for both transcription from and maintenance of mitochondrial genomes. However, the roles of mtTFA have not been extensively studied in cancer cells. Here, we firstly reported the nuclear localization of mtTFA. The proportion of nuclear-localized mtTFA varied among different cancer cells. Some mtTFA binds tightly to the nuclear chromatin. DNA microarray and chromatin immunoprecipitation assays showed that mtTFA can regulate the expression of nuclear genes. Overexpression of mtTFA enhanced the growth of cancer cell lines, whereas downregulation of mtTFA inhibited their growth by regulating mtTFA target genes, such as baculoviral IAP repeat-containing 5 (BIRC5; also known as survivin). Knockdown of mtTFA expression induced p21-dependent G1 cell cycle arrest. These results imply that mtTFA functions in both nuclei and mitochondria to promote cell growth.

  3. Identification of genes regulating growth and fatness traits in pig through hypothalamic transcriptome analysis

    PubMed Central

    Madsen, Ole; Alves, Estefânia; Rodríguez, M. Carmen; Folch, Josep María; Noguera, José Luis; Groenen, Martien A. M.; Fernández, Ana I.

    2013-01-01

    Previous studies on Iberian × Landrace (IBMAP) pig intercrosses have enabled the identification of several quantitative trait locus (QTL) regions related to growth and fatness traits; however, the genetic variation underlying those QTLs are still unknown. These traits are not only relevant because of their impact on economically important production traits, but also because pig constitutes a widely studied animal model for human obesity and obesity-related diseases. The hypothalamus is the main gland regulating growth, food intake, and fat accumulation. Therefore, the aim of this work was to identify genes and/or gene transcripts involved in the determination of growth and fatness in pig by a comparison of the whole hypothalamic transcriptome (RNA-Seq) in two groups of phenotypically divergent IBMAP pigs. Around 16,000 of the ∼25.010 annotated genes were expressed in these hypothalamic samples, with most of them showing intermediate expression levels. Functional analyses supported the key role of the hypothalamus in the regulation of growth, fat accumulation, and energy expenditure. Moreover, 58,927 potentially new isoforms were detected. More than 250 differentially expressed genes and novel transcript isoforms were identified between the two groups of pigs. Twenty-one DE genes/transcripts that colocalized in previously identified QTL regions and/or whose biological functions are related to the traits of interest were explored in more detail. Additionally, the transcription factors potentially regulating these genes and the subjacent networks and pathways were also analyzed. This study allows us to propose strong candidate genes for growth and fatness based on expression patterns, genomic location, and network interactions. PMID:24280257

  4. Regulation of cardiac autophagy by insulin-like growth factor 1.

    PubMed

    Troncoso, Rodrigo; Díaz-Elizondo, Jessica; Espinoza, Sandra P; Navarro-Marquez, Mario F; Oyarzún, Alejandra P; Riquelme, Jaime A; Garcia-Carvajal, Ivonne; Díaz-Araya, Guillermo; García, Lorena; Hill, Joseph A; Lavandero, Sergio

    2013-07-01

    Insulin-like growth factor-1 (IGF-1) signaling is a key pathway in the control of cell growth and survival. Three critical nodes in the IGF-1 signaling pathway have been described in cardiomyocytes: protein kinase Akt/mammalian target of rapamycin (mTOR), Ras/Raf/extracellular signal-regulated kinase (ERK), and phospholipase C (PLC)/inositol 1,4,5-triphosphate (InsP3 )/Ca(2+) . The Akt/mTOR and Ras/Raf/ERK signaling arms govern survival in the settings of cardiac stress and hypertrophic growth. By contrast, PLC/InsP3 /Ca(2+) functions to regulate metabolic adaptability and gene transcription. Autophagy is a catabolic process involved in protein degradation, organelle turnover, and nonselective breakdown of cytoplasmic components during nutrient starvation or stress. In the heart, autophagy is observed in a variety of human pathologies, where it can be either adaptive or maladaptive, depending on the context. We proposed the hypothesis that IGF-1 protects the heart by rescuing the mitochondrial metabolism and the energetics state, reducing cell death and controls the potentially exacerbate autophagic response to nutritional stress. In light of the importance of IGF-1 and autophagy in the heart, we review here IGF-1 signaling and autophagy regulation in the context of cardiomyocyte nutritional stress. PMID:23671040

  5. The siRNA-Mediated Down-Regulation of Vascular Endothelial Growth Factor Receptor1

    PubMed Central

    Jafari Sani, Moslem; Yazdi, Foad; Masoomi Karimi, Masoomeh; Alizadeh, Javad; Rahmati, Majid; Zarei Mahmudabadi, Ali

    2016-01-01

    Background Angiogenesis is an important biological process involved in the proliferation of endothelial cells, tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is considered as a prominent regulator of angiogenesis which exerts the aforementioned effect(s) through its respective receptors (VEGFR1 and VEGFR2). VEGF receptors are targeted as a therapeutic candidate for cancer growth inhibition. RNAi as a new and promising strategy has provided a useful means to specifically suppress gene expression in cancer cells. Objectives The current study aimed to down-regulate expression of the VEGFR1 using siRNA. Materials and Methods This experimental study designed specific siRNAs against VEGFR1. Total RNA was extracted from human umbilical vain endothelial cell (HUVEC) and subsequently cDNA was synthetized. PCR was performed using specific primers to amplify the target gene. After double digestion and purification, the gene was cloned into pEFGP-N1 expression vector. Then, AGS cells were transfected with recombinant pEGFP-N1 using lipofectamin. The gene expression and down-regulation were evaluated by fluorescence scanning, reverse transcription PCR (RT-PCR) and Western blot techniques. Results Fluorescent scanning, RT-PCR (27.68%) and western blot analysis (31.06%) showed that the expression of VEGFR1 was suppressed effectively. Conclusions The results of the current study showed that specifically designed siRNA can be considered as an appropriate strategy to suppress gene expression and might be a promising tool to prevent angiogenesis. PMID:27275397

  6. Regulation of insulin-like growth factor-I in skeletal muscle and muscle cells.

    PubMed

    Frost, R A; Lang, C H

    2003-03-01

    Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are potent regulators of muscle mass. Transgenic mice that over-express these proteins exhibit dramatically enlarged skeletal muscles. In contrast, malnutrition, critical illness, sepsis, and aging are all associated with a dramatic reduction in muscle mass and function. The circulating concentration of IGF-I and the expression of IGF-I in skeletal muscle are also reduced during catabolic states. Consequently, GH has been used clinically to increase lean body mass in patients with muscle wasting. Likewise, delivery of IGF-I specifically into muscle has been proposed as a genetic therapy for muscle disorders. A better understanding of the regulation of IGF-I expression in skeletal muscle and muscle cells is therefore of importance. Yet, our knowledge in this area has been limited by a lack of GH responsive muscle cells. In addition the IGF-I gene spans over 90 kb of genomic DNA and it exhibits a very complex regulatory pattern. This review will summarize our knowledge of the control of muscle mass by GH, IGF-I, anabolic steroids, exercise and other growth enhancing hormones. We will also highlight recent advances in the regulation of IGF-I and signal transducers and activators of transcription (Stats) by GH. A special emphasis will be placed on the interaction of IGF-I and proinflammatory cytokines in skeletal muscle and muscle cells. PMID:12621363

  7. Discovery and characterization of nutritionally regulated genes associated with muscle growth in Atlantic salmon.

    PubMed

    Bower, Neil I; Johnston, Ian A

    2010-10-01

    A genomics approach was used to identify nutritionally regulated genes involved in growth of fast skeletal muscle in Atlantic salmon (Salmo salar L.). Forward and reverse subtractive cDNA libraries were prepared comparing fish with zero growth rates to fish growing rapidly. We produced 7,420 ESTs and assembled them into nonredundant clusters prior to annotation. Contigs representing 40 potentially unrecognized nutritionally responsive candidate genes were identified. Twenty-three of the subtractive library candidates were also differentially regulated by nutritional state in an independent fasting-refeeding experiment and their expression placed in the context of 26 genes with established roles in muscle growth regulation. The expression of these genes was also determined during the maturation of a primary myocyte culture, identifying 13 candidates from the subtractive cDNA libraries with putative roles in the myogenic program. During early stages of refeeding DNAJA4, HSPA1B, HSP90A, and CHAC1 expression increased, indicating activation of unfolded protein response pathways. Four genes were considered inhibitory to myogenesis based on their in vivo and in vitro expression profiles (CEBPD, ASB2, HSP30, novel transcript GE623928). Other genes showed increased expression with feeding and highest in vitro expression during the proliferative phase of the culture (FOXD1, DRG1) or as cells differentiated (SMYD1, RTN1, MID1IP1, HSP90A, novel transcript GE617747). The genes identified were associated with chromatin modification (SMYD1, RTN1), microtubule stabilization (MID1IP1), cell cycle regulation (FOXD1, CEBPD, DRG1), and negative regulation of signaling (ASB2) and may play a role in the stimulation of myogenesis during the transition from a catabolic to anabolic state in skeletal muscle. PMID:20663983

  8. Growth factor regulation of remyelination: behind the growing interest in endogenous cell repair of the CNS.

    PubMed

    Armstrong, Regina C

    2007-11-01

    Remyelination facilitates recovery of saltatory conduction along demyelinated axons and may help prevent axon damage in patients with demyelinating diseases, such as multiple sclerosis. The extent of remyelination in multiple sclerosis lesions varies dramatically, indicating a capacity for repair that is not fulfilled in lesions with poor remyelination. In experimental models of demyelinating disease, remyelination is limited by chronic disease that depletes the oligodendrocyte progenitor (OP) population, inhibits OP differentiation into remyelinating oligodendrocytes and/or perturbs cell survival in the lesion environment. Manipulating the activity of growth factor signaling pathways significantly improves the ability of endogenous OP cells to accomplish extensive remyelination. Specifically, growth factors have been identified that can regulate OP proliferation, differentiation and survival in demyelinated lesions. Therefore, growth factors may be key signals for strategies to improve conditions with poor remyelination. PMID:19079759

  9. RACK1 inhibits colonic cell growth by regulating Src activity at cell cycle checkpoints.

    PubMed

    Mamidipudi, V; Dhillon, N K; Parman, T; Miller, L D; Lee, K C; Cartwright, C A

    2007-05-01

    Previously, we showed that Src tyrosine kinases are activated early in the development of human colon cancer and are suppressed as intestinal cells differentiate. We identified RACK1 as an endogenous substrate, binding partner and inhibitor of Src. Here we show (by overexpressing RACK1, depleting Src or RACK1 and utilizing cell-permeable peptides that perturb RACK1's interaction with Src) that RACK1 regulates growth of colon cells by suppressing Src activity at G(1) and mitotic checkpoints, and consequently delaying cell cycle progression. Activated Src rescues RACK1-inhibited growth of HT-29 cells. Conversely, inhibiting Src abolishes growth promoted by RACK1 depletion in normal cells. Two potential mechanisms whereby RACK1 regulates mitotic exit are identified: suppression of Src-mediated Sam68 phosphorylation and maintenance of the cyclin-dependent kinase (CDK) 1-cyclin B complex in an active state. Our results reveal novel mechanisms of cell cycle control in G(1) and mitosis of colon cells. The significance of this work lies in the discovery of a mechanism by which the growth of colon cancer cells can be slowed, by RACK1 suppression of an oncogenic kinase at critical cell cycle checkpoints. Small molecules that mimic RACK1 function may provide a powerful new approach to the treatment of colon cancer. PMID:17072338

  10. Growth-Blocking Peptides As Nutrition-Sensitive Signals for Insulin Secretion and Body Size Regulation.

    PubMed

    Koyama, Takashi; Mirth, Christen K

    2016-02-01

    In Drosophila, the fat body, functionally equivalent to the mammalian liver and adipocytes, plays a central role in regulating systemic growth in response to nutrition. The fat body senses intracellular amino acids through Target of Rapamycin (TOR) signaling, and produces an unidentified humoral factor(s) to regulate insulin-like peptide (ILP) synthesis and/or secretion in the insulin-producing cells. Here, we find that two peptides, Growth-Blocking Peptide (GBP1) and CG11395 (GBP2), are produced in the fat body in response to amino acids and TOR signaling. Reducing the expression of GBP1 and GBP2 (GBPs) specifically in the fat body results in smaller body size due to reduced growth rate. In addition, we found that GBPs stimulate ILP secretion from the insulin-producing cells, either directly or indirectly, thereby increasing insulin and insulin-like growth factor signaling activity throughout the body. Our findings fill an important gap in our understanding of how the fat body transmits nutritional information to the insulin producing cells to control body size. PMID:26928023

  11. Growth-Blocking Peptides As Nutrition-Sensitive Signals for Insulin Secretion and Body Size Regulation

    PubMed Central

    Koyama, Takashi; Mirth, Christen K.

    2016-01-01

    In Drosophila, the fat body, functionally equivalent to the mammalian liver and adipocytes, plays a central role in regulating systemic growth in response to nutrition. The fat body senses intracellular amino acids through Target of Rapamycin (TOR) signaling, and produces an unidentified humoral factor(s) to regulate insulin-like peptide (ILP) synthesis and/or secretion in the insulin-producing cells. Here, we find that two peptides, Growth-Blocking Peptide (GBP1) and CG11395 (GBP2), are produced in the fat body in response to amino acids and TOR signaling. Reducing the expression of GBP1 and GBP2 (GBPs) specifically in the fat body results in smaller body size due to reduced growth rate. In addition, we found that GBPs stimulate ILP secretion from the insulin-producing cells, either directly or indirectly, thereby increasing insulin and insulin-like growth factor signaling activity throughout the body. Our findings fill an important gap in our understanding of how the fat body transmits nutritional information to the insulin producing cells to control body size. PMID:26928023

  12. DNA supercoiling and the anaerobic and growth phase regulation of tonB gene expression.

    PubMed Central

    Dorman, C J; Barr, G C; Bhriain, N N; Higgins, C F

    1988-01-01

    We show that several interacting environmental factors influence the topology of intracellular DNA. Negative supercoiling of DNA in vivo is increased by anaerobic growth and is also influenced by growth phase. The tonB promoter of Escherichia coli and Salmonella typhimurium was found to be highly sensitive to changes in DNA supercoiling. Expression was increased by novobiocin, an inhibitor of DNA gyrase, and was decreased by factors which increase DNA superhelicity. Expression of the plasmid-encoded tonB gene was enhanced by gamma delta insertions in cis in a distance- and orientation-independent fashion. Both the res site and the TnpR protein of gamma delta, which is known to function as a type I topoisomerase, were required for this activation. tonB expression increased during the growth cycle and was reduced by anaerobiosis. There was excellent correlation between tonB expression from a plasmid and the level of supercoiling of that plasmid under a wide range of conditions. The chromosomal tonB gene was regulated in a manner identical to that of the plasmid-encoded gene. Thus, the physiological regulation of tonB expression in response to anaerobiosis and growth phase appears to be mediated by environmentally induced changes in DNA superhelicity. Images PMID:2836373

  13. Vertebrate heart growth is regulated by functional antagonism between Gridlock and Gata5

    PubMed Central

    Jia, Haibo; King, Isabelle N.; Chopra, Sameer S.; Wan, Haiyan; Ni, Terri T.; Jiang, Charlie; Guan, Xiaoqun; Wells, Sam; Srivastava, Deepak; Zhong, Tao P.

    2007-01-01

    Embryonic organs attain their final dimensions through the generation of proper cell number and size, but the control mechanisms remain obscure. Here, we establish Gridlock (Grl), a Hairy-related basic helix–loop–helix (bHLH) transcription factor, as a negative regulator of cardiomyocyte proliferative growth in zebrafish embryos. Mutations in grl cause an increase in expression of a group of immediate-early growth genes, myocardial genes, and development of hyperplastic hearts. Conversely, cardiomyocytes with augmented Grl activity have diminished cell volume and fail to divide, resulting in a marked reduction in heart size. Both bHLH domain and carboxyl region are required for Grl negative control of myocardial proliferative growth. These Grl-induced cardiac effects are counterbalanced by the transcriptional activator Gata5 but not Gata4, which promotes cardiomyocyte expansion in the embryo. Biochemical analyses show that Grl forms a complex with Gata5 through the carboxyl region and can repress Gata5-mediated transcription via the bHLH domain. Hence, our studies suggest that Grl regulates embryonic heart growth via opposing Gata5, at least in part through their protein interactions in modulating gene expression. PMID:17715064

  14. Heparan sulfate sulfatase SULF2 regulates PDGFRα signaling and growth in human and mouse malignant glioma

    PubMed Central

    Phillips, Joanna J.; Huillard, Emmanuelle; Robinson, Aaron E.; Ward, Anna; Lum, David H.; Polley, Mei-Yin; Rosen, Steven D.; Rowitch, David H.; Werb, Zena

    2012-01-01

    Glioblastoma (GBM), a uniformly lethal brain cancer, is characterized by diffuse invasion and abnormal activation of multiple receptor tyrosine kinase (RTK) signaling pathways, presenting a major challenge to effective therapy. The activation of many RTK pathways is regulated by extracellular heparan sulfate proteoglycans (HSPG), suggesting these molecules may be effective targets in the tumor microenvironment. In this study, we demonstrated that the extracellular sulfatase, SULF2, an enzyme that regulates multiple HSPG-dependent RTK signaling pathways, was expressed in primary human GBM tumors and cell lines. Knockdown of SULF2 in human GBM cell lines and generation of gliomas from Sulf2–/– tumorigenic neurospheres resulted in decreased growth in vivo in mice. We found a striking SULF2 dependence in activity of PDGFRα, a major signaling pathway in GBM. Ablation of SULF2 resulted in decreased PDGFRα phosphorylation and decreased downstream MAPK signaling activity. Interestingly, in a survey of SULF2 levels in different subtypes of GBM, the proneural subtype, characterized by aberrations in PDGFRα, demonstrated the strongest SULF2 expression. Therefore, in addition to its potential as an upstream target for therapy of GBM, SULF2 may help identify a subset of GBMs that are more dependent on exogenous growth factor–mediated signaling. Our results suggest the bioavailability of growth factors from the microenvironment is a significant contributor to tumor growth in a major subset of human GBM. PMID:22293178

  15. Making An Impact: Shatter Cones

    ERIC Educational Resources Information Center

    Blank, Lisa M.; Plautz, Michael R.; Crews, Jeffrey W.

    2004-01-01

    In 1990, a group of geologists discovered a large number of shatter cones in southwestern Montana. Shatter cones are a type of metamorphosed rock often found in impact structures (the remains of a crater after a meteor impact and years of Earth activity). Scientists have discovered only 168 impact craters around the world. If rocks could talk,…

  16. Aerodynamic Rear Cone for Trucks

    NASA Technical Reports Server (NTRS)

    Bullman, J.

    1985-01-01

    Wind-inflated cone reduces turbulence that ordinarily occurs in air just behind square-back truck traveling at high speed. Wind around truck would enter slits in folded cone and automatically deploy it. Energy lost to air turbulence greatly reduced, and fuel consumed by truck reduced accordingly. In addition, less air turbulence means less disturbance to nearby vehicles on highway.

  17. Light capture by human cones.

    PubMed Central

    Chen, B; Makous, W

    1989-01-01

    1. The variation in visual efficiency of light with varying pupillary entry (the Stiles-Crawford effect) was measured to determine the proportion of light incident on the cones that escapes them without recovery by other cones. 2. The variation in detectability of interference fringes with varying pupillary entry of the interfering beams was measured to determine the proportion of incident light that was recaptured by cones in the dark stripes after escaping cones in the bright stripes of the fringes. 3. By exclusion, these observations determine the variation, with varying pupillary entry, in the proportion of incident light that was captured and absorbed by the first cones it entered. 4. Some 70-90% of the light absorbed by the cones when it passes through the centre of the pupil, is entirely lost to the visual system if it passes instead through the margin of the (dilated) pupil. 5. Over half the light that cones absorb when the light enters the margin of the pupil is light that has previously passed through other cones. 6. If the spread of recaptured light is assumed to be Gaussian, its standard deviation is at most one minute of visual angle. 7. Such recaptured light makes a previously unknown contribution to the various Stiles-Crawford effects. PMID:2607444

  18. Comparative analysis of some models of gene regulation in mixed-substrate microbial growth.

    PubMed

    Narang, Atul

    2006-09-21

    Mixed-substrate microbial growth is of fundamental interest in microbiology and bioengineering. Several mathematical models have been developed to account for the genetic regulation of such systems, especially those resulting in diauxic growth. In this work, we compare the dynamics of three such models (Narang, 1998a. The dynamical analogy between microbial growth on mixtures of substrates and population growth of competing species. Biotechnol. Bioeng. 59, 116-121; Thattai and Shraiman, 2003. Metabolic switching in the sugar phosphotransferase system of Escherichia coli. Biophys. J. 85(2), 744-754; Brandt et al., 2004. Modelling microbial adaptation to changing availability of substrates. Water Res. 38, 1004-1013). We show that these models are dynamically similar--the initial motion of the inducible enzymes in all the models is described by the Lotka-Volterra equations for competing species. In particular, the prediction of diauxic growth corresponds to "extinction" of one of the enzymes during the first few hours of growth. The dynamic similarity occurs because in all the models, the inducible enzymes possess properties characteristic of competing species: they are required for their own synthesis, and they inhibit each other. Despite this dynamic similarity, the models vary with respect to the range of dynamics captured. The Brandt et al. model always predicts the diauxic growth pattern, whereas the remaining two models exhibit both diauxic and non-diauxic growth patterns. The models also differ with respect to the mechanisms that generate the mutual inhibition between the enzymes. In the Narang model, mutual inhibition occurs because the enzymes for each substrate enhance the dilution of the enzymes for the other substrate. The Brandt et al. model superimposes upon this dilution effect an additional mechanism of mutual inhibition. In the Thattai and Shraiman model, the mutual inhibition is entirely due to competition for the phosphoryl groups. For quantitative

  19. Spartin Regulates Synaptic Growth and Neuronal Survival by Inhibiting BMP-Mediated Microtubule Stabilization

    PubMed Central

    Nahm, Minyeop; Lee, Min-Jung; Parkinson, William; Lee, Mihye; Kim, Haeran; Kim, Yoon-Jung; Kim, Sungdae; Cho, Yi Sul; Min, Byung-Moo; Bae, Yong Chul; Broadie, Kendal; Lee, Seungbok

    2013-01-01

    SUMMARY Troyer syndrome is a hereditary spastic paraplegia caused by human spartin (SPG20) gene mutations. We have generated a Drosophila disease model showing that Spartin functions presynaptically with endocytic adaptor Eps15 to regulate synaptic growth and function. Spartin inhibits bone morphogenetic protein (BMP) signaling by promoting endocytic degradation of BMP receptor wishful thinking (Wit). Drosophila fragile X mental retardation protein (dFMRP) and Futsch/MAP1B are downstream effectors of Spartin and BMP signaling in regulating microtubule stability and synaptic growth. Loss of Spartin or elevation of BMP signaling induces age-dependent progressive defects resembling hereditary spastic paraplegias, including motor dysfunction and brain neurodegeneration. Null spartin phenotypes are prevented by administration of the microtubule-destabilizing drug vinblastine. Together, these results demonstrate that Spartin regulates both synaptic development and neuronal survival by controlling microtubule stability via the BMP-dFMRP-Futsch pathway, suggesting that impaired regulation of microtubule stability is a core pathogenic component in Troyer syndrome. PMID:23439121

  20. MicroRNAs as growth regulators, their function and biomarker status in colorectal cancer

    PubMed Central

    Cekaite, Lina; Eide, Peter W.; Lind, Guro E.; Skotheim, Rolf I.; Lothe, Ragnhild A.

    2016-01-01

    Gene expression is in part regulated by microRNAs (miRNAs). This review summarizes the current knowledge of miRNAs in colorectal cancer (CRC); their role as growth regulators, the mechanisms that regulate the miRNAs themselves and the potential of miRNAs as biomarkers. Although thousands of tissue samples and bodily fluids from CRC patients have been investigated for biomarker potential of miRNAs (>160 papers presented in a comprehensive tables), none single miRNA nor miRNA expression signatures are in clinical use for this disease. More than 500 miRNA-target pairs have been identified in CRC and we discuss how these regulatory nodes interconnect and affect signaling pathways in CRC progression. PMID:26623728

  1. Conditional Cooperativity of Toxin - Antitoxin Regulation Can Mediate Bistability between Growth and Dormancy

    PubMed Central

    Cataudella, Ilaria; Sneppen, Kim; Gerdes, Kenn; Mitarai, Namiko

    2013-01-01

    Many toxin-antitoxin operons are regulated by the toxin/antitoxin ratio by mechanisms collectively coined “conditional cooperativity”. Toxin and antitoxin form heteromers with different stoichiometric ratios, and the complex with the intermediate ratio works best as a transcription repressor. This allows transcription at low toxin level, strong repression at intermediate toxin level, and then again transcription at high toxin level. Such regulation has two interesting features; firstly, it provides a non-monotonous response to the concentration of one of the proteins, and secondly, it opens for ultra-sensitivity mediated by the sequestration of the functioning heteromers. We explore possible functions of conditional regulation in simple feedback motifs, and show that it can provide bistability for a wide range of parameters. We then demonstrate that the conditional cooperativity in toxin-antitoxin systems combined with the growth-inhibition activity of free toxin can mediate bistability between a growing state and a dormant state. PMID:24009488

  2. Conditional cooperativity of toxin - antitoxin regulation can mediate bistability between growth and dormancy.

    PubMed

    Cataudella, Ilaria; Sneppen, Kim; Gerdes, Kenn; Mitarai, Namiko

    2013-01-01

    Many toxin-antitoxin operons are regulated by the toxin/antitoxin ratio by mechanisms collectively coined "conditional cooperativity". Toxin and antitoxin form heteromers with different stoichiometric ratios, and the complex with the intermediate ratio works best as a transcription repressor. This allows transcription at low toxin level, strong repression at intermediate toxin level, and then again transcription at high toxin level. Such regulation has two interesting features; firstly, it provides a non-monotonous response to the concentration of one of the proteins, and secondly, it opens for ultra-sensitivity mediated by the sequestration of the functioning heteromers. We explore possible functions of conditional regulation in simple feedback motifs, and show that it can provide bistability for a wide range of parameters. We then demonstrate that the conditional cooperativity in toxin-antitoxin systems combined with the growth-inhibition activity of free toxin can mediate bistability between a growing state and a dormant state. PMID:24009488

  3. Smad-Independent Transforming Growth Factor-β Regulation of Early Growth Response-1 and Sustained Expression in Fibrosis

    PubMed Central

    Bhattacharyya, Swati; Chen, Shu-Jen; Wu, Minghua; Warner-Blankenship, Matthew; Ning, Hongyan; Lakos, Gabriella; Mori, Yasuji; Chang, Eric; Nihijima, Chihiro; Takehara, Kazuhiro; Feghali-Bostwick, Carol; Varga, John

    2008-01-01

    Transforming growth factor-β (TGF-β) plays a key role in scleroderma pathogenesis. The transcription factor early growth response-1 (Egr-1) mediates the stimulation of collagen transcription elicited by TGF-β and is necessary for the development of pulmonary fibrosis in mice. Here, we report that TGF-β causes a time- and dose-dependent increase in Egr-1 protein and mRNA levels and enhanced transcription of the Egr-1 gene via serum response elements in normal fibroblasts. The ability of TGF-β to stimulate Egr-1 was preserved in Smad3-null mice and in explanted Smad3-null fibroblasts. The response was blocked by a specific mitogen-activated protein kinase kinase 1 (MEK1) inhibitor but not by an ALK5 kinase inhibitor. Furthermore, MEK1 was phosphorylated by TGF-β, which was sufficient to drive Egr-1 transactivation. Stimulation by TGF-β enhanced the transcriptional activity of Elk-1 via the MEK-extracellular signal-regulated kinase 1/2 pathway. Bleomycin-induced scleroderma in the mouse was accompanied by increased Egr-1 accumulation in lesional fibroblasts. Furthermore, biopsies of lesional skin and lung from patients with scleroderma showed increased Egr-1 levels, which were highest in early diffuse disease. Moreover, both Egr-1 mRNA and protein were elevated in explanted scleroderma skin fibroblasts in vitro. Together, these findings define a Smad-independent TGF-β signal transduction mechanism that underlies the stimulation of Egr-1, demonstrate for the first time sustained Egr-1 up-regulation in fibrotic lesions and suggests that Egr-1 has a role in the induction and progression of fibrosis. PMID:18772333

  4. Regulation of Tenon's Capsule Fibroblast Cell Proliferation by the Opioid Growth Factor and the Opioid Growth Factor Receptor Axis

    PubMed Central

    Klocek, Matthew S.; Sassani, Joseph W.; Donahue, Renee N.; McLaughlin, Patricia J.

    2010-01-01

    Purpose. Glaucoma filtration surgery often fails because of the fibrotic reaction from Tenon's capsule fibroblasts (TCFs). This study examined whether the interaction of the opioid growth factor (OGF) [Met5]-enkephalin with its receptor (OGFr) is a regulator of TCF proliferation. Methods. The presence of OGF and its receptor (OGFr) was determined in rabbit TCFs (RTCFs) by immunocytochemistry. The kinetics of OGFr were established in receptor binding assays. The ability of OGF to inhibit RTCF proliferation was assessed with dose–response, receptor mediation, and reversibility studies. Dependence on OGF and OGFr was ascertained by antibody neutralization and siRNA studies, respectively. The mechanism of action of the OGF–OGFr axis on survival (apoptosis, necrosis) and DNA synthesis of RTCFs was elucidated. Results. OGF and OGFr were detected in RTCF cells, and specific and saturable binding to OGFr was recorded. Exogenous OGF had a dose-dependent, reversible, and receptor-mediated inhibitory effect on cell proliferation. Endogenous OGF was found to be constitutively produced and tonically active in cell replication, with neutralization of this peptide causing acceleration of cell proliferation. The silencing of OGFr by using siRNA technology stimulated cell replication, validating OGFr's integral role. The mechanism of OGF–OGFr action was not related to cell survival, but rather to DNA synthesis—specifically, the cyclin-dependent kinase inhibitory pathway. Knockdown of p16 or p21 eliminated OGF's inhibitory effect on growth. Conclusions. The OGF–OGFr system is a native biological regulator of cell proliferation in RTCFs and may offer a means of improving the success of glaucoma filtration surgery in a safe and nontoxic manner. PMID:20463323

  5. NGL-2 Regulates Pathway-Specific Neurite Growth and Lamination, Synapse Formation, and Signal Transmission in the Retina

    PubMed Central

    Watkins, Kelly L.; Johnson, Robert E.; Schottler, Frank

    2013-01-01

    Parallel processing is an organizing principle of many neural circuits. In the retina, parallel neuronal pathways process signals from rod and cone photoreceptors and support vision over a wide range of light levels. Toward this end, rods and cones form triad synapses with dendrites of distinct bipolar cell types, and the axons or dendrites, respectively, of horizontal cells (HCs). The molecular cues that promote the formation of specific neuronal pathways remain largely unknown. Here, we discover that developing and mature HCs express the leucine-rich repeat (LRR)-containing protein netrin-G ligand 2 (NGL-2). NGL-2 localizes selectively to the tips of HC axons, which form reciprocal connections with rods. In mice with null mutations in Ngl-2 (Ngl-2−/−), many branches of HC axons fail to stratify in the outer plexiform layer (OPL) and invade the outer nuclear layer. In addition, HC axons expand lateral territories and increase coverage of the OPL, but establish fewer synapses with rods. NGL-2 can form transsynaptic adhesion complexes with netrin-G2, which we show to be expressed by photoreceptors. In Ngl-2−/− mice, we find specific defects in the assembly of presynaptic ribbons in rods, indicating that reverse signaling of complexes involving NGL-2 regulates presynaptic maturation. The development of HC dendrites and triad synapses of cone photoreceptors proceeds normally in the absence of NGL-2 and in vivo electrophysiology reveals selective defects in rod-mediated signal transmission in Ngl-2−/− mice. Thus, our results identify NGL-2 as a central component of pathway-specific development in the outer retina. PMID:23864682

  6. Regulation and expression of a growth arrest-specific gene (gas5) during growth, differentiation, and development.

    PubMed Central

    Coccia, E M; Cicala, C; Charlesworth, A; Ciccarelli, C; Rossi, G B; Philipson, L; Sorrentino, V

    1992-01-01

    The growth arrest-specific gas5 gene was isolated from mouse genomic DNA and structurally characterized. The transcriptional unit is divided into 12 exons that span around 7 kb. An alternative splicing mechanism gives rise to two mature mRNAs which contain either 11 or 12 exons, and both are found in the cytoplasm of growth-arrested cells. In vivo, the gas5 gene is ubiquitously expressed in mouse tissues during development and adult life. In Friend leukemia and NIH 3T3 cells, the levels of gas5 gene mRNA were high in saturation density-arrested cells and almost undetectable in actively growing cells. Run-on experiments indicated that the gas5 gene is transcribed at the same level in both growing and arrested cells. On the other hand, in dimethyl sulfoxide-induced differentiating cells a sharp decrease in the rate of transcription was observed shortly before the cells reached the postmitotic stage. These results indicate that in density-arrested cells accumulation of gas5 mRNA is controlled at the posttranscriptional level while in differentiating cells expression is regulated transcriptionally. Images PMID:1630459

  7. Brg1 Enables Rapid Growth of the Early Embryo by Suppressing Genes That Regulate Apoptosis and Cell Growth Arrest.

    PubMed

    Singh, Ajeet P; Foley, Julie F; Rubino, Mark; Boyle, Michael C; Tandon, Arpit; Shah, Ruchir; Archer, Trevor K

    2016-08-01

    SWI/SNF (switching/sucrose nonfermenting)-dependent chromatin remodeling establishes coordinated gene expression programs during development, yet important functional details remain to be elucidated. We show that the Brg1 (Brahma-related gene 1; Smarca4) ATPase is globally expressed at high levels during postimplantation development and its conditional ablation, beginning at gastrulation, results in increased apoptosis, growth retardation, and, ultimately, embryonic death. Global gene expression analysis revealed that genes upregulated in Rosa26CreERT2; Brg1(flox/flox) embryos (here referred to as Brg1(d/d) embryos to describe embryos with deletion of the Brg1(flox/flox) alleles) negatively regulate cell cycle progression and cell growth. In addition, the p53 (Trp53) protein, which is virtually undetectable in early wild-type embryos, accumulated in the Brg1(d/d) embryos and activated the p53-dependent pathways. Using P19 cells, we show that Brg1 and CHD4 (chromodomain helicase DNA binding protein 4) coordinate to control target gene expression. Both proteins physically interact and show a substantial overlap of binding sites at chromatin-accessible regions adjacent to genes differentially expressed in the Brg1(d/d) embryos. Specifically, Brg1 deficiency results in reduced levels of the repressive histone H3 lysine K27 trimethylation (H3K27me3) histone mark and an increase in the amount of open chromatin at the regulatory region of the p53 and p21 (Cdkn1a) genes. These results provide insights into the mechanisms by which Brg1 functions, which is in part via the p53 program, to constrain gene expression and facilitate rapid embryonic growth. PMID:27185875

  8. Geological constraints on the dynamic emplacement of cone-sheets - The Ardnamurchan cone-sheet swarm, NW Scotland

    NASA Astrophysics Data System (ADS)

    Mathieu, Lucie; Burchardt, Steffi; Troll, Valentin R.; Krumbholz, Michael; Delcamp, Audray

    2015-11-01

    Cone-sheets are a significant constituent of many central volcanoes, where they contribute to volcano growth by intrusion and through flank eruptions, although the exact emplacement mechanisms are still controversially discussed. In particular, it is not yet fully resolved whether cone-sheets propagate as magma-driven, opening-mode fractures or as shear fractures, and to what extent pre-existing host-rock structures and different stress fields influence cone-sheet emplacement. To shed further light on the role of these parameters in cone-sheet emplacement, we use detailed field and remote sensing data of the classic Ardnamurchan cone-sheet swarm in NW-Scotland, and we show that the cone-sheets primarily propagated as opening-mode fractures in the σ1-σ2 plane of the volcanic stress field. In addition, more than one third of the Ardnamurchan cone-sheet segments are parallel to lineaments that form a conjugate set of NNW and WNW striking fractures and probably reflect the regional NW-SE orientation of σ1 during emplacement in the Palaeogene. Cone-sheets exploit these lineaments within the NE and SW sectors of the Ardnamurchan central complex, which indicates that the local volcanic stress field dominated during sheet propagation and only allowed exploitation of host-rock discontinuities that were approximately parallel to the sheet propagation path. In addition, outcrop-scale deflections of cone-sheets into sills and back into cone-sheets (also referred to as "staircase" geometry) are explained by the interaction of stresses at the propagating sheet tip with variations in host-rock strength, as well as the influence of sheet-induced strain. As a consequence, cone-sheets associated with sill-like segments propagate as mixed-mode I/II fractures. Hence, cone-sheet emplacement requires a dynamic model that takes into account stress fields at various scales and the way propagating magma interacts with the host rock and its inherent variations in rock strength.

  9. FAK regulates platelet extravasation and tumor growth after antiangiogenic therapy withdrawal.

    PubMed

    Haemmerle, Monika; Bottsford-Miller, Justin; Pradeep, Sunila; Taylor, Morgan L; Choi, Hyun-Jin; Hansen, Jean M; Dalton, Heather J; Stone, Rebecca L; Cho, Min Soon; Nick, Alpa M; Nagaraja, Archana S; Gutschner, Tony; Gharpure, Kshipra M; Mangala, Lingegowda S; Rupaimoole, Rajesha; Han, Hee Dong; Zand, Behrouz; Armaiz-Pena, Guillermo N; Wu, Sherry Y; Pecot, Chad V; Burns, Alan R; Lopez-Berestein, Gabriel; Afshar-Kharghan, Vahid; Sood, Anil K

    2016-05-01

    Recent studies in patients with ovarian cancer suggest that tumor growth may be accelerated following cessation of antiangiogenesis therapy; however, the underlying mechanisms are not well understood. In this study, we aimed to compare the effects of therapy withdrawal to those of continuous treatment with various antiangiogenic agents. Cessation of therapy with pazopanib, bevacizumab, and the human and murine anti-VEGF antibody B20 was associated with substantial tumor growth in mouse models of ovarian cancer. Increased tumor growth was accompanied by tumor hypoxia, increased tumor angiogenesis, and vascular leakage. Moreover, we found hypoxia-induced ADP production and platelet infiltration into tumors after withdrawal of antiangiogenic therapy, and lowering platelet counts markedly inhibited tumor rebound after withdrawal of antiangiogenic therapy. Focal adhesion kinase (FAK) in platelets regulated their migration into the tumor microenvironment, and FAK-deficient platelets completely prevented the rebound tumor growth. Additionally, combined therapy with a FAK inhibitor and the antiangiogenic agents pazopanib and bevacizumab reduced tumor growth and inhibited negative effects following withdrawal of antiangiogenic therapy. In summary, these results suggest that FAK may be a unique target in situations in which antiangiogenic agents are withdrawn, and dual targeting of FAK and VEGF could have therapeutic implications for ovarian cancer management. PMID:27064283

  10. Nutrient/TOR-dependent regulation of RNA polymerase III controls tissue and organismal growth in Drosophila.

    PubMed

    Marshall, Lynne; Rideout, Elizabeth J; Grewal, Savraj S

    2012-04-18

    The nutrient/target-of-rapamycin (TOR) pathway has emerged as a key regulator of tissue and organismal growth in metazoans. The signalling components of the nutrient/TOR pathway are well defined; however, the downstream effectors are less understood. Here, we show that the control of RNA polymerase (Pol) III-dependent transcription is an essential target of TOR in Drosophila. We find that TOR activity controls Pol III in growing larvae via inhibition of the repressor Maf1 and, in part, via the transcription factor Drosophila Myc (dMyc). Moreover, we show that loss of the Pol III factor, Brf, leads to reduced tissue and organismal growth and prevents TOR-induced cellular growth. TOR activity in the larval fat body, a tissue equivalent to vertebrate fat or liver, couples nutrition to insulin release from the brain. Accordingly, we find that fat-specific loss of Brf phenocopies nutrient limitation and TOR inhibition, leading to decreased systemic insulin signalling and reduced organismal growth. Thus, stimulation of Pol III is a key downstream effector of TOR in the control of cellular and systemic growth. PMID:22367393

  11. Substrate flexibility regulates growth and apoptosis of normal but not transformed cells

    NASA Technical Reports Server (NTRS)

    Wang, H. B.; Dembo, M.; Wang, Y. L.

    2000-01-01

    One of the hallmarks of oncogenic transformation is anchorage-independent growth (27). Here we demonstrate that responses to substrate rigidity play a major role in distinguishing the growth behavior of normal cells from that of transformed cells. We cultured normal or H-ras-transformed NIH 3T3 cells on flexible collagen-coated polyacrylamide substrates with similar chemical properties but different rigidity. Compared with cells cultured on stiff substrates, nontransformed cells on flexible substrates showed a decrease in the rate of DNA synthesis and an increase in the rate of apoptosis. These responses on flexible substrates are coupled to decreases in cell spreading area and traction forces. In contrast, transformed cells maintained their growth and apoptotic characteristics regardless of substrate flexibility. The responses in cell spreading area and traction forces to substrate flexibility were similarly diminished. Our results suggest that normal cells are capable of probing substrate rigidity and that proper mechanical feedback is required for regulating cell shape, cell growth, and survival. The loss of this response can explain the unregulated growth of transformed cells.

  12. N-docosahexaenoylethanolamine regulates Hedgehog signaling and promotes growth of cortical axons

    PubMed Central

    Kharebava, Giorgi; Rashid, Mohammad A.; Lee, Ji-Won; Sarkar, Sarmila; Kevala, Karl; Kim, Hee-Yong

    2015-01-01

    ABSTRACT Axonogenesis, a process for the establishment of neuron connectivity, is central to brain function. The role of metabolites derived from docosahexaenoic acid (DHA, 22:6n-3) that is specifically enriched in the brain, has not been addressed in axon development. In this study, we tested if synaptamide (N-docosahexaenoylethanolamine), an endogenous metabolite of DHA, affects axon growth in cultured cortical neurons. We found that synaptamide increased the average axon length, inhibited GLI family zinc finger 1 (GLI1) transcription and sonic hedgehog (Shh) target gene expression while inducing cAMP elevation. Similar effects were produced by cyclopamine, a regulator of the Shh pathway. Conversely, Shh antagonized elevation of cAMP and blocked synaptamide-mediated increase in axon length. Activation of Shh pathway by a smoothened (SMO) agonist (SAG) or overexpression of SMO did not inhibit axon growth mediated by synaptamide or cyclopamine. Instead, adenylate cyclase inhibitor SQ22536 abolished synaptamide-mediated axon growth indicating requirement of cAMP elevation for this process. Our findings establish that synaptamide promotes axon growth while Shh antagonizes synaptamide-mediated cAMP elevation and axon growth by a SMO-independent, non-canonical pathway. PMID:26545965

  13. FAK regulates platelet extravasation and tumor growth after antiangiogenic therapy withdrawal

    PubMed Central

    Haemmerle, Monika; Bottsford-Miller, Justin; Pradeep, Sunila; Taylor, Morgan L.; Hansen, Jean M.; Dalton, Heather J.; Stone, Rebecca L.; Cho, Min Soon; Nick, Alpa M.; Nagaraja, Archana S.; Gutschner, Tony; Gharpure, Kshipra M.; Mangala, Lingegowda S.; Han, Hee Dong; Zand, Behrouz; Armaiz-Pena, Guillermo N.; Wu, Sherry Y.; Pecot, Chad V.; Burns, Alan R.; Lopez-Berestein, Gabriel; Afshar-Kharghan, Vahid; Sood, Anil K.

    2016-01-01

    Recent studies in patients with ovarian cancer suggest that tumor growth may be accelerated following cessation of antiangiogenesis therapy; however, the underlying mechanisms are not well understood. In this study, we aimed to compare the effects of therapy withdrawal to those of continuous treatment with various antiangiogenic agents. Cessation of therapy with pazopanib, bevacizumab, and the human and murine anti-VEGF antibody B20 was associated with substantial tumor growth in mouse models of ovarian cancer. Increased tumor growth was accompanied by tumor hypoxia, increased tumor angiogenesis, and vascular leakage. Moreover, we found hypoxia-induced ADP production and platelet infiltration into tumors after withdrawal of antiangiogenic therapy, and lowering platelet counts markedly inhibited tumor rebound after withdrawal of antiangiogenic therapy. Focal adhesion kinase (FAK) in platelets regulated their migration into the tumor microenvironment, and FAK-deficient platelets completely prevented the rebound tumor growth. Additionally, combined therapy with a FAK inhibitor and the antiangiogenic agents pazopanib and bevacizumab reduced tumor growth and inhibited negative effects following withdrawal of antiangiogenic therapy. In summary, these results suggest that FAK may be a unique target in situations in which antiangiogenic agents are withdrawn, and dual targeting of FAK and VEGF could have therapeutic implications for ovarian cancer management. PMID:27064283

  14. Cyclin G Functions as a Positive Regulator of Growth and Metabolism in Drosophila.

    PubMed

    Fischer, Patrick; La Rosa, Martina K; Schulz, Adriana; Preiss, Anette; Nagel, Anja C

    2015-08-01

    In multicellular organisms, growth and proliferation is adjusted to nutritional conditions by a complex signaling network. The Insulin receptor/target of rapamycin (InR/TOR) signaling cascade plays a pivotal role in nutrient dependent growth regulation in Drosophila and mammals alike. Here we identify Cyclin G (CycG) as a regulator of growth and metabolism in Drosophila. CycG mutants have a reduced body size and weight and show signs of starvation accompanied by a disturbed fat metabolism. InR/TOR signaling activity is impaired in cycG mutants, combined with a reduced phosphorylation status of the kinase Akt1 and the downstream factors S6-kinase and eukaryotic translation initiation factor 4E binding protein (4E-BP). Moreover, the expression and accumulation of Drosophila insulin like peptides (dILPs) is disturbed in cycG mutant brains. Using a reporter assay, we show that the activity of one of the first effectors of InR signaling, Phosphoinositide 3-kinase (PI3K92E), is unaffected in cycG mutants. However, the metabolic defects and weight loss in cycG mutants were rescued by overexpression of Akt1 specifically in the fat body and by mutants in widerborst (wdb), the B'-subunit of the phosphatase PP2A, known to downregulate Akt1 by dephosphorylation. Together, our data suggest that CycG acts at the level of Akt1 to regulate growth and metabolism via PP2A in Drosophila. PMID:26274446

  15. The Yeast Sks1p Kinase Signaling Network Regulates Pseudohyphal Growth and Glucose Response

    PubMed Central

    Johnson, Cole; Kweon, Hye Kyong; Sheidy, Daniel; Shively, Christian A.; Mellacheruvu, Dattatreya; Nesvizhskii, Alexey I.; Andrews, Philip C.; Kumar, Anuj

    2014-01-01

    The yeast Saccharomyces cerevisiae undergoes a dramatic growth transition from its unicellular form to a filamentous state, marked by the formation of pseudohyphal filaments of elongated and connected cells. Yeast pseudohyphal growth is regulated by signaling pathways responsive to reductions in the availability of nitrogen and glucose, but the molecular link between pseudohyphal filamentation and glucose signaling is not fully understood. Here, we identify the glucose-responsive Sks1p kinase as a signaling protein required for pseudohyphal growth induced by nitrogen limitation and coupled nitrogen/glucose limitation. To identify the Sks1p signaling network, we applied mass spectrometry-based quantitative phosphoproteomics, profiling over 900 phosphosites for phosphorylation changes dependent upon Sks1p kinase activity. From this analysis, we report a set of novel phosphorylation sites and highlight Sks1p-dependent phosphorylation in Bud6p, Itr1p, Lrg1p, Npr3p, and Pda1p. In particular, we analyzed the Y309 and S313 phosphosites in the pyruvate dehydrogenase subunit Pda1p; these residues are required for pseudohyphal growth, and Y309A mutants exhibit phenotypes indicative of impaired aerobic respiration and decreased mitochondrial number. Epistasis studies place SKS1 downstream of the G-protein coupled receptor GPR1 and the G-protein RAS2 but upstream of or at the level of cAMP-dependent PKA. The pseudohyphal growth and glucose signaling transcription factors Flo8p, Mss11p, and Rgt1p are required to achieve wild-type SKS1 transcript levels. SKS1 is conserved, and deletion of the SKS1 ortholog SHA3 in the pathogenic fungus Candida albicans results in abnormal colony morphology. Collectively, these results identify Sks1p as an important regulator of filamentation and glucose signaling, with additional relevance towards understanding stress-responsive signaling in C. albicans. PMID:24603354

  16. Regulation of fibroblast growth factor receptor signalling and trafficking by Src and Eps8

    PubMed Central

    Auciello, Giulio; Cunningham, Debbie L.; Tatar, Tulin; Heath, John K.; Rappoport, Joshua Z.

    2013-01-01

    Summary Fibroblast growth factor receptors (FGFRs) mediate a wide spectrum of cellular responses that are crucial for development and wound healing. However, aberrant FGFR activity leads to cancer. Activated growth factor receptors undergo stimulated endocytosis, but can continue to signal along the endocytic pathway. Endocytic trafficking controls the duration and intensity of signalling, and growth factor receptor signalling can lead to modifications of trafficking pathways. We have developed live-cell imaging methods for studying FGFR dynamics to investigate mechanisms that coordinate the interplay between receptor trafficking and signal transduction. Activated FGFR enters the cell following recruitment to pre-formed clathrin-coated pits (CCPs). However, FGFR activation stimulates clathrin-mediated endocytosis; FGF treatment increases the number of CCPs, including those undergoing endocytosis, and this effect is mediated by Src and its phosphorylation target Eps8. Eps8 interacts with the clathrin-mediated endocytosis machinery and depletion of Eps8 inhibits FGFR trafficking and immediate Erk signalling. Once internalized, FGFR passes through peripheral early endosomes en route to recycling and degredative compartments, through an Src- and Eps8-dependent mechanism. Thus Eps8 functions as a key coordinator in the interplay between FGFR signalling and trafficking. This work provides the first detailed mechanistic analysis of growth factor receptor clustering at the cell surface through signal transduction and endocytic trafficking. As we have characterised the Src target Eps8 as a key regulator of FGFR signalling and trafficking, and identified the early endocytic system as the site of Eps8-mediated effects, this work provides novel mechanistic insight into the reciprocal regulation of growth factor receptor signalling and trafficking. PMID:23203811

  17. Extracellular matrix density regulates the rate of neovessel growth and branching in sprouting angiogenesis.

    PubMed

    Edgar, Lowell T; Underwood, Clayton J; Guilkey, James E; Hoying, James B; Weiss, Jeffrey A

    2014-01-01

    Angiogenesis is regulated by the local microenvironment, including the mechanical interactions between neovessel sprouts and the extracellular matrix (ECM). However, the mechanisms controlling the relationship of mechanical and biophysical properties of the ECM to neovessel growth during sprouting angiogenesis are just beginning to be understood. In this research, we characterized the relationship between matrix density and microvascular topology in an in vitro 3D organ culture model of sprouting angiogenesis. We used these results to design and calibrate a computational growth model to demonstrate how changes in individual neovessel behavior produce the changes in vascular topology that were observed experimentally. Vascularized gels with higher collagen densities produced neovasculatures with shorter vessel lengths, less branch points, and reduced network interconnectivity. The computational model was able to predict these experimental results by scaling the rates of neovessel growth and branching according to local matrix density. As a final demonstration of utility of the modeling framework, we used our growth model to predict several scenarios of practical interest that could not be investigated experimentally using the organ culture model. Increasing the density of the ECM significantly reduced angiogenesis and network formation within a 3D organ culture model of angiogenesis. Increasing the density of the matrix increases the stiffness of the ECM, changing how neovessels are able to deform and remodel their surroundings. The computational framework outlined in this study was capable of predicting this observed experimental behavior by adjusting neovessel growth rate and branching probability according to local ECM density, demonstrating that altering the stiffness of the ECM via increasing matrix density affects neovessel behavior, thereby regulated vascular topology during angiogenesis. PMID:24465500

  18. Effects of chronic growth hormone overexpression on appetite-regulating brain gene expression in coho salmon.

    PubMed

    Kim, Jin-Hyoung; Leggatt, Rosalind A; Chan, Michelle; Volkoff, Hélène; Devlin, Robert H

    2015-09-15

    Organisms must carefully regulate energy intake and expenditure to balance growth and trade-offs with other physiological processes. This regulation is influenced by key pathways controlling appetite, feeding behaviour and energy homeostasis. Growth hormone (GH) transgenesis provides a model where food intake can be elevated, and is associated with dramatic modifications of growth, metabolism, and feeding behaviour, particularly in fish. RNA-Seq and qPCR analyses were used to compare the expression of multiple genes important in appetite regulation within brain regions and the pituitary gland (PIT) of GH transgenic (fed fully to satiation or restricted to a wild-type ration throughout their lifetime) and wild-type coho salmon (Oncorhynchus kisutch). RNA-Seq results showed that differences in both genotype and ration levels resulted in differentially expressed genes associated with appetite regulation in transgenic fish, including elevated Agrp1 in hypothalamus (HYP) and reduced Mch in PIT. Altered mRNA levels for Agrp1, Npy, Gh, Ghr, Igf1, Mch and Pomc were also assessed using qPCR analysis. Levels of mRNA for Agrp1, Gh, and Ghr were higher in transgenic than wild-type fish in HYP and in the preoptic area (POA), with Agrp1 more than 7-fold higher in POA and 12-fold higher in HYP of transgenic salmon compared to wild-type fish. These data are consistent with the known roles of orexigenic factors on foraging behaviour acting via GH and through MC4R receptor-mediated signalling. Igf1 mRNA was elevated in fully-fed transgenic fish in HYP and POA, but not in ration-restricted fish, yet both of these types of transgenic animals have very pronounced feeding behaviour relative to wild-type fish, suggesting IGF1 is not playing a direct role in appetite stimulation acting via paracrine or autocrine mechanisms. The present findings provide new insights on mechanisms ruling altered appetite regulation in response to chronically elevated GH, and on potential pathways by which

  19. mTORC1 regulates PTHrP to coordinate chondrocyte growth, proliferation and differentiation.

    PubMed

    Yan, Bo; Zhang, Zhongmin; Jin, Dadi; Cai, Chen; Jia, Chunhong; Liu, Wen; Wang, Ting; Li, Shengfa; Zhang, Haiyan; Huang, Bin; Lai, Pinglin; Wang, Hua; Liu, Anling; Zeng, Chun; Cai, Daozhang; Jiang, Yu; Bai, Xiaochun

    2016-01-01

    Precise coordination of cell growth, proliferation and differentiation is essential for the development of multicellular organisms. Here, we report that although the mechanistic target of rapamycin complex 1 (mTORC1) activity is required for chondrocyte growth and proliferation, its inactivation is essential for chondrocyte differentiation. Hyperactivation of mTORC1 via TSC1 gene deletion in chondrocytes causes uncoupling of the normal proliferation and differentiation programme within the growth plate, resulting in uncontrolled cell proliferation, and blockage of differentiation and chondrodysplasia in mice. Rapamycin promotes chondrocyte differentiation and restores these defects in mutant mice. Mechanistically, mTORC1 downstream kinase S6K1 interacts with and phosphorylates Gli2, and releases Gli2 from SuFu binding, resulting in nuclear translocation of Gli2 and transcription of parathyroid hormone-related peptide (PTHrP), a key regulator of bone development. Our findings demonstrate that dynamically controlled mTORC1 activity is crucial to coordinate chondrocyte proliferation and differentiation partially through regulating Gli2/PTHrP during endochondral bone development. PMID:27039827

  20. Forkhead box transcription factor FoxC1 preserves corneal transparency by regulating vascular growth

    PubMed Central

    Seo, Seungwoon; Singh, Hardeep P.; Lacal, Pedro M.; Sasman, Amy; Fatima, Anees; Liu, Ting; Schultz, Kathryn M.; Losordo, Douglas W.; Lehmann, Ordan J.; Kume, Tsutomu

    2012-01-01

    Normal vision requires the precise control of vascular growth to maintain corneal transparency. Here we provide evidence for a unique mechanism by which the Forkhead box transcription factor FoxC1 regulates corneal vascular development. Murine Foxc1 is essential for development of the ocular anterior segment, and in humans, mutations have been identified in Axenfeld–Rieger syndrome, a disorder characterized by anterior segment dysgenesis. We show that FOXC1 mutations also lead to corneal angiogenesis, and that mice homozygous for either a global (Foxc1−/−) or neural crest (NC)-specific (NC-Foxc1−/−) null mutation display excessive growth of corneal blood and lymphatic vessels. This is associated with disorganization of the extracellular matrix and increased expression of multiple matrix metalloproteinases. Heterozygous mutants (Foxc1+/− and NC-Foxc1+/−) exhibit milder phenotypes, such as disrupted limbal vasculature. Moreover, environmental exposure to corneal injury significantly increases growth of both blood and lymphatic vessels in both Foxc1+/− and NC-Foxc1+/− mice compared with controls. Notably, this amplification of the angiogenic response is abolished by inhibition of VEGF receptor 2. Collectively, these findings identify a role for FoxC1 in inhibiting corneal angiogenesis, thereby maintaining corneal transparency by regulating VEGF signaling. PMID:22171010

  1. mTORC1 regulates PTHrP to coordinate chondrocyte growth, proliferation and differentiation

    PubMed Central

    Yan, Bo; Zhang, Zhongmin; Jin, Dadi; Cai, Chen; Jia, Chunhong; Liu, Wen; Wang, Ting; Li, Shengfa; Zhang, Haiyan; Huang, Bin; Lai, Pinglin; Wang, Hua; Liu, Anling; Zeng, Chun; Cai, Daozhang; Jiang, Yu; Bai, Xiaochun

    2016-01-01

    Precise coordination of cell growth, proliferation and differentiation is essential for the development of multicellular organisms. Here, we report that although the mechanistic target of rapamycin complex 1 (mTORC1) activity is required for chondrocyte growth and proliferation, its inactivation is essential for chondrocyte differentiation. Hyperactivation of mTORC1 via TSC1 gene deletion in chondrocytes causes uncoupling of the normal proliferation and differentiation programme within the growth plate, resulting in uncontrolled cell proliferation, and blockage of differentiation and chondrodysplasia in mice. Rapamycin promotes chondrocyte differentiation and restores these defects in mutant mice. Mechanistically, mTORC1 downstream kinase S6K1 interacts with and phosphorylates Gli2, and releases Gli2 from SuFu binding, resulting in nuclear translocation of Gli2 and transcription of parathyroid hormone-related peptide (PTHrP), a key regulator of bone development. Our findings demonstrate that dynamically controlled mTORC1 activity is crucial to coordinate chondrocyte proliferation and differentiation partially through regulating Gli2/PTHrP during endochondral bone development. PMID:27039827

  2. Regulation of Intracellular Structural Tension by Talin in the Axon Growth and Regeneration.

    PubMed

    Dingyu, Wang; Fanjie, Meng; Zhengzheng, Ding; Baosheng, Huang; Chao, Yang; Yi, Pan; Huiwen, Wu; Jun, Guo; Gang, Hu

    2016-09-01

    Intracellular tension is the most important characteristic of neuron polarization as well as the growth and regeneration of axons, which can be generated by motor proteins and conducted along the cytoskeleton. To better understand this process, we created Förster resonance energy transfer (FRET)-based tension probes that can be incorporated into microfilaments to provide a real-time measurement of forces in neuron cytoskeletons. We found that our probe could be used to assess the structural tension of neuron polarity. Nerve growth factor (NGF) upregulated structural forces, whereas the glial-scar inhibitors chondroitin sulfate proteoglycan (CSPG) and aggrecan weakened such forces. Notably, the tension across axons was distributed uniformly and remarkably stronger than that in the cell body in NGF-stimulated neurons. The mechanosensors talin/vinculin could antagonize the effect of glial-scar inhibitors via structural forces. However, E-cadherin was closely associated with glial-scar inhibitor-induced downregulation of structural forces. Talin/vinculin was involved in the negative regulation of E-cadherin transcription through the nuclear factor-kappa B pathway. Collectively, this study clarified the mechanism underlying intracellular tension in the growth and regeneration of axons which, conversely, can be regulated by talin and E-cadherin. PMID:26298665

  3. E. coli 6S RNA: a universal transcriptional regulator within the centre of growth adaptation.

    PubMed

    Geissen, René; Steuten, Benedikt; Polen, Tino; Wagner, Rolf

    2010-01-01

    Bacterial 6S RNA has been shown to bind with high affinity to σ(70)-containing RNA polymerase, suppressing σ(70)-dependent transcription during stationary phase, when 6S RNA concentrations are highest. We recently reported a genome-wide transcriptional comparison of wild-type and 6S RNA deficient E. coli strains. Contrary to the expected σ(70)- and stationary phase-specific regulatory effect of 6S RNA it turned out that mRNA levels derived from many alternative sigma factors, including σ(38) or σ(32), were affected during exponential and stationary growth. Among the most noticeably down-regulated genes at stationary growth are ribosomal proteins and factors involved in translation. In addition, a striking number of mRNA levels coding for enzymes involved in the purine metabolism, for transporters and stress regulators are altered both during log- and stationary phase. During the study we discovered a link between 6S RNA and the general stress alarmone ppGpp, which has a higher basal level in cells deficient in 6S RNA. This finding points to a functional interrelation of 6S RNA and the global network of stress and growth adaptation. PMID:20930516

  4. Thyroid hormone regulation of epidermal growth factor receptor levels in mouse mammary glands

    SciTech Connect

    Vonderhaar, B.K.; Tang, E.; Lyster, R.R.; Nascimento, M.C.

    1986-08-01

    The specific binding of iodinated epidermal growth factor ((/sup 125/I)iodo-EGF) to membranes prepared from the mammary glands and spontaneous breast tumors of euthyroid and hypothyroid mice was measured in order to determine whether thyroid hormones regulate the EGF receptor levels in vivo. Membranes from hypothyroid mammary glands of mice at various developmental ages bound 50-65% less EGF than those of age-matched euthyroid controls. Treatment of hypothyroid mice with L-T4 before killing restored binding to the euthyroid control level. Spontaneous breast tumors arising in hypothyroid mice also bound 30-40% less EGF than tumors from euthyroid animals even after in vitro desaturation of the membranes of endogenous growth factors with 3 M MgCl2 treatment. The decrease in binding in hypothyroid membranes was due to a decrease in the number of binding sites, not to a change in affinity of the growth factor for its receptor, as determined by Scatchard analysis of the binding data. Both euthyroid and hypothyroid membranes bound EGF primarily to a single class of high affinity sites (dissociation constant (Kd) = 0.7-1.8 nM). Euthyroid membranes bound 28.4 +/- (SE) 0.6 fmol/mg protein, whereas hypothyroid membranes bound 15.5 +/- 1.0 fmol/mg protein. These data indicate that EGF receptor levels in normal mammary glands and spontaneous breast tumors in mice are subject to regulation by thyroid status.

  5. Caloric Restriction Normalizes Obesity-Induced Alterations on Regulators of Skeletal Muscle Growth Signaling.

    PubMed

    Dungan, Cory M; Li, Ji; Williamson, David L

    2016-08-01

    The objective of this study was to establish the impact of caloric restriction on high fat diet-induced alterations on regulators of skeletal muscle growth. We hypothesized that caloric restriction would reverse the negative effects of high fat diet-induced obesity on REDD1 and mTOR-related signaling. Following an initial 8 week period of HF diet-induced obesity, caloric restriction (CR ~30 %) was employed while mice continued to consume either a low (LF) or high fat (HF) diet for 8 weeks. Western analysis of skeletal muscle showed that CR reduced (p < 0.05) the obesity-related effects on the lipogenic protein, SREBP1. Likewise, CR reduced (p < 0.05) the obesity-related effects on the hyperactivation of mTORC1 and ERK1/2 signaling to levels comparable to the LF mice. CR also reduced (p < 0.05) obesity-induced expression of negative regulators of growth, REDD1 and cleaved caspase 3. These findings have implications for on the reversibility of dysregulated growth signaling in obese skeletal muscle, using short-term caloric restriction. PMID:27289530

  6. Lysyl oxidase binds transforming growth factor-beta and regulates its signaling via amine oxidase activity.

    PubMed

    Atsawasuwan, Phimon; Mochida, Yoshiyuki; Katafuchi, Michitsuna; Kaku, Masaru; Fong, Keith S K; Csiszar, Katalin; Yamauchi, Mitsuo

    2008-12-01

    Lysyl oxidase (LOX), an amine oxidase critical for the initiation of collagen and elastin cross-linking, has recently been shown to regulate cellular activities possibly by modulating the functions of growth factors. In this study, we investigated the interaction between LOX and transforming growth factor-beta1 (TGF-beta1), a potent growth factor abundant in bone, the effect of LOX on TGF-beta1 signaling, and its potential mechanism. The specific binding between mature LOX and mature TGF-beta1 was demonstrated by immunoprecipitation and glutathione S-transferase pulldown assay in vitro. Both proteins were colocalized in the extracellular matrix in an osteoblastic cell culture system, and the binding complex was identified in the mineral-associated fraction of bone matrix. Furthermore, LOX suppressed TGF-beta1-induced Smad3 phosphorylation likely through its amine oxidase activity. The data indicate that LOX binds to mature TGF-beta1 and enzymatically regulates its signaling in bone and thus may play an important role in bone maintenance and remodeling. PMID:18835815

  7. ROCK1 via LIM kinase regulates growth, maturation and actin based functions in mast cells

    PubMed Central

    Kapur, Reuben; Shi, Jianjian; Ghosh, Joydeep; Munugalavadla, Veerendra; Sims, Emily; Martin, Holly; Wei, Lei; Mali, Raghuveer Singh

    2016-01-01

    Understanding mast cell development is essential due to their critical role in regulating immunity and autoimmune diseases. Here, we show how Rho kinases (ROCK) regulate mast cell development and can function as therapeutic targets for treating allergic diseases. Rock1 deficiency results in delayed maturation of bone marrow derived mast cells (BMMCs) in response to IL-3 stimulation and reduced growth in response to stem cell factor (SCF) stimulation. Further, integrin-mediated adhesion and migration, and IgE-mediated degranulation are all impaired in Rock1-deficient BMMCs. To understand the mechanism behind altered mast cell development in Rock1−/− BMMCs, we analyzed the activation of ROCK and its downstream targets including LIM kinase (LIMK). We observed reduced activation of ROCK, LIMK, AKT and ERK1/2 in Rock1-deficient BMMCs in response to SCF stimulation. Further, loss of either Limk1 or Limk2 also demonstrated altered BMMC maturation and growth; combined deletion of both Limk1 and Limk2 resulted in further reduction in BMMC maturation and growth. In passive cutaneous anaphylaxis model, deficiency of Rock1 or treatment with ROCK inhibitor Fasudil protected mice against IgE-mediated challenge. Our results identify ROCK/LIMK pathway as a novel therapeutic target for treating allergic diseases involving mast cells. PMID:26943578

  8. Mxi1 regulates cell proliferation through insulin-like growth factor binding protein-3

    SciTech Connect

    Ko, Je Yeong; Yoo, Kyung Hyun; Lee, Han-Woong; Park, Jong Hoon

    2011-11-11

    Highlights: Black-Right-Pointing-Pointer Mxi1 regulates cell proliferation. Black-Right-Pointing-Pointer Expression of IGFBP-3 is regulated by Mxi1. Black-Right-Pointing-Pointer Inactivation of Mxi1 reduces IGFBP-3 expression in vitro and in vivo. -- Abstract: Mxi1, a member of the Myc-Max-Mad network, is an antagonist of the c-Myc oncogene and is associated with excessive cell proliferation. Abnormal cell proliferation and tumorigenesis are observed in organs of Mxi1-/- mice. However, the Mxi1-reltaed mechanism of proliferation is unclear. The present study utilized microarray analysis using Mxi1 mouse embryonic fibroblasts (MEFs) to identify genes associated with cell proliferation. Among these genes, insulin-like growth factor binding protein-3 (IGFBP-3) was selected as a candidate gene for real-time PCR to ascertain whether IGFBP-3 expression is regulated by Mxi1. Expression of IGFBP-3 was decreased in Mxi1-/- MEFs and Mxi1-/- mice, and the gene was regulated by Mxi1 in Mxi1 MEFs. Furthermore, proliferation pathways related to IGFBP-3 were regulated in Mxi1-/- mice compared to Mxi1+/+ mice. To determine the effect of Mxi1 inactivation on the induction of cell proliferation, a proliferation assay is performed in both Mxi1 MEFs and Mxi1 mice. Cell viability was regulated by Mxi1 in Mxi1 MEFs and number of PCNA-positive cells was increased in Mxi1-/- mice compared to Mxi1+/+ mice. Moreover, the IGFBP-3 level was decreased in proliferation defect regions in Mxi1-/- mice. The results support the suggestion that inactivation of Mxi1 has a positive effect on cell proliferation by down-regulating IGFBP-3.

  9. Plasma membrane H+-ATPase regulation is required for auxin gradient formation preceding phototropic growth

    PubMed Central

    Hohm, Tim; Demarsy, Emilie; Quan, Clément; Allenbach Petrolati, Laure; Preuten, Tobias; Vernoux, Teva; Bergmann, Sven; Fankhauser, Christian

    2014-01-01

    Phototropism is a growth response allowing plants to align their photosynthetic organs toward incoming light and thereby to optimize photosynthetic activity. Formation of a lateral gradient of the phytohormone auxin is a key step to trigger asymmetric growth of the shoot leading to phototropic reorientation. To identify important regulators of auxin gradient formation, we developed an auxin flux model that enabled us to test in silico the impact of different morphological and biophysical parameters on gradient formation, including the contribution of the extracellular space (cell wall) or apoplast. Our model indicates that cell size, cell distributions, and apoplast thickness are all important factors affecting gradient formation. Among all tested variables, regulation of apoplastic pH was the most important to enable the formation of a lateral auxin gradient. To test this prediction, we interfered with the activity of plasma membrane H+-ATPases that are required to control apoplastic pH. Our results show that H+-ATPases are indeed important for the establishment of a lateral auxin gradient and phototropism. Moreover, we show that during phototropism, H+-ATPase activity is regulated by the phototropin photoreceptors, providing a mechanism by which light influences apoplastic pH. PMID:25261457

  10. Identifying growth hormone-regulated enhancers in the Igf1 locus.

    PubMed

    Alzhanov, Damir; Mukherjee, Aditi; Rotwein, Peter

    2015-11-01

    Growth hormone (GH) plays a central role in regulating somatic growth and in controlling multiple physiological processes in humans and other vertebrates. A key agent in many GH actions is the secreted peptide, IGF-I. As established previously, GH stimulates IGF-I gene expression via the Stat5b transcription factor, leading to production of IGF-I mRNAs and proteins. However, the precise mechanisms by which GH-activated Stat5b promotes IGF-I gene transcription have not been defined. Unlike other GH-regulated genes, there are no Stat5b sites near either of the two IGF-I gene promoters. Although dispersed GH-activated Stat5b binding elements have been mapped in rodent Igf1 gene chromatin, it is unknown how these distal sites might function as potential transcriptional enhancers. Here we have addressed mechanisms of regulation of IGF-I gene transcription by GH by generating cell lines in which the rat Igf1 chromosomal locus has been incorporated into the mouse genome. Using these cells we find that physiological levels of GH rapidly and potently activate Igf1 gene transcription while stimulating physical interactions in chromatin between inducible Stat5b-binding elements and the Igf1 promoters. We have thus developed a robust experimental platform for elucidating how dispersed transcriptional enhancers control Igf1 gene expression under different biological conditions. PMID:26330488

  11. The Ret receptor regulates sensory neuron dendrite growth and integrin mediated adhesion

    PubMed Central

    Soba, Peter; Han, Chun; Zheng, Yi; Perea, Daniel; Miguel-Aliaga, Irene; Jan, Lily Yeh; Jan, Yuh Nung

    2015-01-01

    Neurons develop highly stereotyped receptive fields by coordinated growth of their dendrites. Although cell surface cues play a major role in this process, few dendrite specific signals have been identified to date. We conducted an in vivo RNAi screen in Drosophila class IV dendritic arborization (C4da) neurons and identified the conserved Ret receptor, known to play a role in axon guidance, as an important regulator of dendrite development. The loss of Ret results in severe dendrite defects due to loss of extracellular matrix adhesion, thus impairing growth within a 2D plane. We provide evidence that Ret interacts with integrins to regulate dendrite adhesion via rac1. In addition, Ret is required for dendrite stability and normal F-actin distribution suggesting it has an essential role in dendrite maintenance. We propose novel functions for Ret as a regulator in dendrite patterning and adhesion distinct from its role in axon guidance. DOI: http://dx.doi.org/10.7554/eLife.05491.001 PMID:25764303

  12. 14-3-3 proteins regulate Tctp-Rheb interaction for organ growth in Drosophila.

    PubMed

    Le, Thao Phuong; Vuong, Linh Thuong; Kim, Ah-Ram; Hsu, Ya-Chieh; Choi, Kwang-Wook

    2016-01-01

    14-3-3 family proteins regulate multiple signalling pathways. Understanding biological functions of 14-3-3 proteins has been limited by the functional redundancy of conserved isotypes. Here we provide evidence that 14-3-3 proteins regulate two interacting components of Tor signalling in Drosophila, translationally controlled tumour protein (Tctp) and Rheb GTPase. Single knockdown of 14-3-3ɛ or 14-3-3ζ isoform does not show obvious defects in organ development but causes synergistic genetic interaction with Tctp and Rheb to impair tissue growth. 14-3-3 proteins physically interact with Tctp and Rheb. Knockdown of both 14-3-3 isoforms abolishes the binding between Tctp and Rheb, disrupting organ development. Depletion of 14-3-3s also reduces the level of phosphorylated S6 kinase, phosphorylated Thor/4E-BP and cyclin E (CycE). Growth defects from knockdown of 14-3-3 and Tctp are suppressed by CycE overexpression. This study suggests a novel mechanism of Tor regulation mediated by 14-3-3 interaction with Tctp and Rheb. PMID:27151460

  13. 14-3-3 proteins regulate Tctp–Rheb interaction for organ growth in Drosophila

    PubMed Central

    Le, Thao Phuong; Vuong, Linh Thuong; Kim, Ah-Ram; Hsu, Ya-Chieh; Choi, Kwang-Wook

    2016-01-01

    14-3-3 family proteins regulate multiple signalling pathways. Understanding biological functions of 14-3-3 proteins has been limited by the functional redundancy of conserved isotypes. Here we provide evidence that 14-3-3 proteins regulate two interacting components of Tor signalling in Drosophila, translationally controlled tumour protein (Tctp) and Rheb GTPase. Single knockdown of 14-3-3ɛ or 14-3-3ζ isoform does not show obvious defects in organ development but causes synergistic genetic interaction with Tctp and Rheb to impair tissue growth. 14-3-3 proteins physically interact with Tctp and Rheb. Knockdown of both 14-3-3 isoforms abolishes the binding between Tctp and Rheb, disrupting organ development. Depletion of 14-3-3s also reduces the level of phosphorylated S6 kinase, phosphorylated Thor/4E-BP and cyclin E (CycE). Growth defects from knockdown of 14-3-3 and Tctp are suppressed by CycE overexpression. This study suggests a novel mechanism of Tor regulation mediated by 14-3-3 interaction with Tctp and Rheb. PMID:27151460

  14. Transcriptional and posttranslational regulation of insulin-like growth factor binding protein-3 by Akt3

    PubMed Central

    Jin, Quanri; Lee, Hyo-Jong; Min, Hye-Young; Smith, John Kendal; Hwang, Su Jung; Whang, Young Mi; Kim, Woo-Young; Kim, Yeul Hong; Lee, Ho-Young

    2014-01-01

    Insulin-like growth factor (IGF)-dependent and -independent antitumor activities of insulin-like growth factor binding protein-3 (IGFBP-3) have been proposed in human non-small cell lung cancer (NSCLC) cells. However, the mechanism underlying regulation of IGFBP-3 expression in NSCLC cells is not well understood. In this study, we show that activation of Akt, especially Akt3, plays a major role in the mRNA expression and protein stability of IGFBP-3 and thus antitumor activities of IGFBP-3 in NSCLC cells. When Akt was activated by genomic or pharmacologic approaches, IGFBP-3 transcription and protein stability were decreased. Conversely, suppression of Akt increased IGFBP-3 mRNA levels and protein stability in NSCLC cell lines. Characterization of the effects of constitutively active form of each Akt subtype (HA-Akt-DD) on IGFBP-3 expression in NSCLC cells and a xenograft model indicated that Akt3 plays a major role in the Akt-mediated regulation of IGFBP-3 expression and thus suppression of Akt effectively enhances the antitumor activities of IGFBP-3 in NSCLC cells with Akt3 overactivation. Collectively, these data suggest a novel function of Akt3 as a negative regulator of IGFBP-3, indicating the possible benefit of a combined inhibition of IGFBP-3 and Akt3 for the treatment of patients with NSCLC. PMID:24942865

  15. Differentially Phased Leaf Growth and Movements in Arabidopsis Depend on Coordinated Circadian and Light Regulation[W

    PubMed Central

    Dornbusch, Tino; Michaud, Olivier; Xenarios, Ioannis; Fankhauser, Christian

    2014-01-01

    In contrast to vastly studied hypocotyl growth, little is known about diel regulation of leaf growth and its coordination with movements such as changes in leaf elevation angle (hyponasty). We developed a 3D live-leaf growth analysis system enabling simultaneous monitoring of growth and movements. Leaf growth is maximal several hours after dawn, requires light, and is regulated by daylength, suggesting coupling between growth and metabolism. We identify both blade and petiole positioning as important components of leaf movements in Arabidopsis thaliana and reveal a temporal delay between growth and movements. In hypocotyls, the combination of circadian expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5 and their light-regulated protein stability drives rhythmic hypocotyl elongation with peak growth at dawn. We find that PIF4 and PIF5 are not essential to sustain rhythmic leaf growth but influence their amplitude. Furthermore, EARLY FLOWERING3, a member of the evening complex (EC), is required to maintain the correct phase between growth and movement. Our study shows that the mechanisms underlying rhythmic hypocotyl and leaf growth differ. Moreover, we reveal the temporal relationship between leaf elongation and movements and demonstrate the importance of the EC for the coordination of these phenotypic traits. PMID:25281688

  16. Transonic Flow Past Cone Cylinders

    NASA Technical Reports Server (NTRS)

    Solomon, George E

    1955-01-01

    Experimental results are presented for transonic flow post cone-cylinder, axially symmetric bodies. The drag coefficient and surface Mach number are studied as the free-stream Mach number is varied and, wherever possible, the experimental results are compared with theoretical predictions. Interferometric results for several typical flow configurations are shown and an example of shock-free supersonic-to-subsonic compression is experimentally demonstrated. The theoretical problem of transonic flow past finite cones is discussed briefly and an approximate solution of the axially symmetric transonic equations, valid for a semi-infinite cone, is presented.

  17. Growth Regulator Changes in Cotton Associated with Defoliation Caused by Verticillium albo-atrum.

    PubMed

    Wiese, M V; Devay, J E

    1970-03-01

    Cotton plants, variety Acala 4-42 family 77 (Gossypium hirsutum L.,), were stem puncture-inoculated with either a defoliating isolate (T9) or a nondefoliating isolate (SS4) of Verticillium albo-atrum (Reinke and Berth.). As symptoms developed, growth regulators were assayed in diseased plants to discern their importance in the disease syndrome.An Avena coleoptile straight growth bioassay demonstrated the presence of several growth-regulatory compounds in cotton tissue extracts. Indoleacetic acid was among the compounds whose effects on coleoptile growth were influenced by disease development. Coleoptile growth due to indoleacetic acid was greater in extracts of diseased stems and leaves than in extracts of comparable healthy tissues. During the defoliation period the T9 and SS4 isolates appeared equally effective in increasing indoleacetic acid and reducing indoleacetic acid decarboxylation. Preceding defoliation, however, in plants showing equivalent symptoms the degradation of auxin was reduced more by infection with T9, the defoliating isolate. The reduced auxin degradation appeared to be releated to concomitant increases in caffeic acid and other indoleacetic acid-oxidase inhibitors in the affected tissues.Abscisic acid in tissue extracts strongly inhibited coleoptile growth. During the defoliation period gas-liquid chromatographic and ultraviolet absorption measurements revealed that abscisic acid levels were approximately doubled in T9-infected leaves but were relatively unaffected in leaves infected with the nondefoliating isolate and in stems infected with either isolate.The onset of epinasty and especially defoliation was also accompanied by increased ethylene production in diseased plants. Ethylene in gas samples taken from jars confining plants infected with SS4 or T9, respectively, was increased 2- and 5-fold over uninoculated controls. Ethylene supplied exogenously to healthy plants in concentrations as low as 0.2 microliter per liter induced both the

  18. Growth Regulator Changes in Cotton Associated with Defoliation Caused by Verticillium albo-atrum1

    PubMed Central

    Wiese, M. V.; Devay, J. E.

    1970-01-01

    Cotton plants, variety Acala 4-42 family 77 (Gossypium hirsutum L.,), were stem puncture-inoculated with either a defoliating isolate (T9) or a nondefoliating isolate (SS4) of Verticillium albo-atrum (Reinke and Berth.). As symptoms developed, growth regulators were assayed in diseased plants to discern their importance in the disease syndrome. An Avena coleoptile straight growth bioassay demonstrated the presence of several growth-regulatory compounds in cotton tissue extracts. Indoleacetic acid was among the compounds whose effects on coleoptile growth were influenced by disease development. Coleoptile growth due to indoleacetic acid was greater in extracts of diseased stems and leaves than in extracts of comparable healthy tissues. During the defoliation period the T9 and SS4 isolates appeared equally effective in increasing indoleacetic acid and reducing indoleacetic acid decarboxylation. Preceding defoliation, however, in plants showing equivalent symptoms the degradation of auxin was reduced more by infection with T9, the defoliating isolate. The reduced auxin degradation appeared to be releated to concomitant increases in caffeic acid and other indoleacetic acid-oxidase inhibitors in the affected tissues. Abscisic acid in tissue extracts strongly inhibited coleoptile growth. During the defoliation period gas-liquid chromatographic and ultraviolet absorption measurements revealed that abscisic acid levels were approximately doubled in T9-infected leaves but were relatively unaffected in leaves infected with the nondefoliating isolate and in stems infected with either isolate. The onset of epinasty and especially defoliation was also accompanied by increased ethylene production in diseased plants. Ethylene in gas samples taken from jars confining plants infected with SS4 or T9, respectively, was increased 2- and 5-fold over uninoculated controls. Ethylene supplied exogenously to healthy plants in concentrations as low as 0.2 microliter per liter induced both

  19. Application of photoremovable protecting group for controlled release of plant growth regulators by sunlight.

    PubMed

    Atta, Sanghamitra; Ikbal, Mohammed; Kumar, Ashutosh; Pradeep Singh, N D

    2012-06-01

    We report a novel technique for controlled release of plant growth regulators (PGRs) by sunlight using photoremovable protecting group (PRPG) as a delivery device. In the present work, carboxyl-containing PGRs of the auxin group [indoleacetic acid (IAA) and naphthoxyacetic acid (NOAA)] were chemically caged using PRPGs of coumarin derivatives. Photophysical studies showed that caged PGRs exhibited good fluorescence properties. Irradiation of caged PGRs by sunlight in both aqueous ethanol and soil media resulted in controlled release of PGRs. The results of the bioactivity experiments indicated that caged PGRs showed better enhancement in the root and shoot length growth of Cicer arietinum compared to PGRs after 10days of sunlight exposure. Our results indicated that use of PRPG as a delivery device for controlled release of PGRs by sunlight in soil holds great interest for field application since it can overcome the rapid loss of PGRs in environmental conditions. PMID:22513094

  20. Oligosaccharins, brassinolides, and jasmonates: nontraditional regulators of plant growth, development, and gene expression.

    PubMed Central

    Creelman, R A; Mullet, J E

    1997-01-01

    Each of the nontraditional plant hormones reviewed in this article, oligosaccharins, brassinolides, and JA, can exert major effects on plant growth and development. However, in many cases, the mechanisms by which these compounds are involved in the endogenous regulation of morphogenesis remain to be established. Nevertheless, the use of mutant or transgenic plants with altered levels or perception of these hormones is leading to phenomenal increases in our understanding of the roles they play in the life cycle of plants. It is likely that in the future, novel modulators of plant growth and development will be identified; some will perhaps be related to the peptide encoded by ENOD40 (Van de Sande et al., 1996), which modifies the action of auxin. PMID:9254935

  1. Polycomb repressive complex 2 regulates skeletal growth by suppressing Wnt and TGF-β signalling.

    PubMed

    Mirzamohammadi, Fatemeh; Papaioannou, Garyfallia; Inloes, Jennifer B; Rankin, Erinn B; Xie, Huafeng; Schipani, Ernestina; Orkin, Stuart H; Kobayashi, Tatsuya

    2016-01-01

    Polycomb repressive complex 2 (PRC2) controls maintenance and lineage determination of stem cells by suppressing genes that regulate cellular differentiation and tissue development. However, the role of PRC2 in lineage-committed somatic cells is mostly unknown. Here we show that Eed deficiency in chondrocytes causes severe kyphosis and a growth defect with decreased chondrocyte proliferation, accelerated hypertrophic differentiation and cell death with reduced Hif1a expression. Eed deficiency also causes induction of multiple signalling pathways in chondrocytes. Wnt signalling overactivation is responsible for the accelerated hypertrophic differentiation and kyphosis, whereas the overactivation of TGF-β signalling is responsible for the reduced proliferation and growth defect. Thus, our study demonstrates that PRC2 has an important regulatory role in lineage-committed tissue cells by suppressing overactivation of multiple signalling pathways. PMID:27329220

  2. Nerve growth factor regulates synaptophysin expression in developing trigeminal ganglion neurons in vitro.

    PubMed

    Tarsa, L; Balkowiec, A

    2009-02-01

    The role of neuronal growth factors in synaptic maturation of sensory neurons, including trigeminal ganglion (TG) neurons, remains poorly understood. Here, we show that nerve growth factor (NGF) regulates the intracellular distribution of the synaptic vesicle protein synaptophysin (Syp) in newborn rat TG neurons in vitro. While reducing the number of Syp-positive cell bodies, NGF dramatically increases Syp immunoreactivity in both proximal and distal segments of the neurite. Intriguingly, the increase in Syp immunoreactivity occurs only in neuron-enriched cultures, in which the number of non-neuronal cells is significantly reduced. Together, our data indicate that NGF is a candidate molecule involved in early postnatal maturation of TG neurons, including control of presynaptic assembly, and thereby formation of synaptic connections. PMID:19019428

  3. Nerve Growth Factor Regulates Synaptophysin Expression In Developing Trigeminal Ganglion Neurons In Vitro

    PubMed Central

    Tarsa, L.; Balkowiec, A.

    2008-01-01

    The role of neuronal growth factors in synaptic maturation of sensory neurons, including trigeminal ganglion (TG) neurons, remains poorly understood. Here, we show that nerve growth factor (NGF) regulates the intracellular distribution of the synaptic vesicle protein synaptophysin (Syp) in newborn rat TG neurons in vitro. While reducing the number of Syp-positive cell bodies, NGF dramatically increases Syp immunoreactivity in both proximal and distal segments of the neurite. Intriguingly, the increase in Syp immunoreactivity occurs only in neuron-enriched cultures, in which the number of non-neuronal cells is significantly reduced. Together, our data indicate that NGF is a candidate molecule involved in early postnatal maturation of TG neurons, including control of presynaptic assembly, and thereby formation of synaptic connections. PMID:19019428

  4. Polycomb repressive complex 2 regulates skeletal growth by suppressing Wnt and TGF-β signalling

    PubMed Central

    Mirzamohammadi, Fatemeh; Papaioannou, Garyfallia; Inloes, Jennifer B.; Rankin, Erinn B.; Xie, Huafeng; Schipani, Ernestina; Orkin, Stuart H.; Kobayashi, Tatsuya

    2016-01-01

    Polycomb repressive complex 2 (PRC2) controls maintenance and lineage determination of stem cells by suppressing genes that regulate cellular differentiation and tissue development. However, the role of PRC2 in lineage-committed somatic cells is mostly unknown. Here we show that Eed deficiency in chondrocytes causes severe kyphosis and a growth defect with decreased chondrocyte proliferation, accelerated hypertrophic differentiation and cell death with reduced Hif1a expression. Eed deficiency also causes induction of multiple signalling pathways in chondrocytes. Wnt signalling overactivation is responsible for the accelerated hypertrophic differentiation and kyphosis, whereas the overactivation of TGF-β signalling is responsible for the reduced proliferation and growth defect. Thus, our study demonstrates that PRC2 has an important regulatory role in lineage-committed tissue cells by suppressing overactivation of multiple signalling pathways. PMID:27329220

  5. PDK1 regulates growth through Akt and S6K in Drosophila

    PubMed Central

    Rintelen, Felix; Stocker, Hugo; Thomas, George; Hafen, Ernst

    2001-01-01

    The insulin/insulin-like growth factor-1 signaling pathway promotes growth in invertebrates and vertebrates by increasing the levels of phosphatidylinositol 3,4,5-triphosphate through the activation of p110 phosphatidylinositol 3-kinase. Two key effectors of this pathway are the phosphoinositide-dependent protein kinase 1 (PDK1) and Akt/PKB. Although genetic analysis in Caenorhabditis elegans has implicated Akt as the only relevant PDK1 substrate, cell culture studies have suggested that PDK1 has additional targets. Here we show that, in Drosophila, dPDK1 controls cellular and organism growth by activating dAkt and S6 kinase, dS6K. Furthermore, dPDK1 genetically interacts with dRSK but not with dPKN, encoding two substrates of PDK1 in vitro. Thus, the results suggest that dPDK1 is required for dRSK but not dPKN activation and that it regulates insulin-mediated growth through two main effector branches, dAkt and dS6K. PMID:11752451

  6. The angiogenesis regulator vasohibin-1 inhibits ovarian cancer growth and peritoneal dissemination and prolongs host survival.

    PubMed

    Takahashi, Yoshifumi; Saga, Yasushi; Koyanagi, Takahiro; Takei, Yuji; Machida, Sizuo; Taneichi, Akiyo; Mizukami, Hiroaki; Sato, Yasufumi; Matsubara, Shigeki; Fujiwara, Hiroyuki

    2015-12-01

    Vasohibin-1 (VASH1) is expressed in vascular endothelial cells stimulated by several angiogenic growth factors and displays autocrine activity to regulate angiogenesis via a negative feedback mechanism. In this study, we investigated the effect of VASH1 on ovarian cancer progression using VASH1-expressing ovarian cancer cells in vitro and in vivo. The growth ability of ovarian cancer cells engineered to express the VASH1 gene remained unchanged in vitro. However, we showed that VASH1 secretion by tumor cells inhibited the growth of human umbilical vein endothelial cells. Further, animal experiments showed that VASH1 expression inhibited tumor angiogenesis and growth. In a murine model of peritoneal dissemination of ovarian cancer cells, VASH1 inhibited peritoneal dissemination and ascites, resulting in significantly prolonged survival in mice. This indicates that VASH1 exerts an antitumor effect on ovarian cancer by inhibiting angiogenesis in the tumor environment. These findings suggest that a novel therapy based on VASH1 could be a useful therapeutic strategy for ovarian cancer. PMID:26460696

  7. The angiogenesis regulator vasohibin-1 inhibits ovarian cancer growth and peritoneal dissemination and prolongs host survival

    PubMed Central

    TAKAHASHI, YOSHIFUMI; SAGA, YASUSHI; KOYANAGI, TAKAHIRO; TAKEI, YUJI; MACHIDA, SIZUO; TANEICHI, AKIYO; MIZUKAMI, HIROAKI; SATO, YASUFUMI; MATSUBARA, SHIGEKI; FUJIWARA, HIROYUKI

    2015-01-01

    Vasohibin-1 (VASH1) is expressed in vascular endothelial cells stimulated by several angiogenic growth factors and displays autocrine activity to regulate angiogenesis via a negative feedback mechanism. In this study, we investigated the effect of VASH1 on ovarian cancer progression using VASH1-expressing ovarian cancer cells in vitro and in vivo. The growth ability of ovarian cancer cells engineered to express the VASH1 gene remained unchanged in vitro. However, we showed that VASH1 secretion by tumor cells inhibited the growth of human umbilical vein endothelial cells. Further, animal experiments showed that VASH1 expression inhibited tumor angiogenesis and growth. In a murine model of peritoneal dissemination of ovarian cancer cells, VASH1 inhibited peritoneal dissemination and ascites, resulting in significantly prolonged survival in mice. This indicates that VASH1 exerts an antitumor effect on ovarian cancer by inhibiting angiogenesis in the tumor environment. These findings suggest that a novel therapy based on VASH1 could be a useful therapeutic strategy for ovarian cancer. PMID:26460696

  8. PKC alpha mediates maternal touch regulation of growth-related gene expression in infant rats.

    PubMed

    Schanberg, Saul M; Ingledue, Vickie F; Lee, Joanna Y; Hannun, Yusuf A; Bartolome, Jorge V

    2003-06-01

    During short-term periods of separation of rat pups from their mothers, the loss of certain sensory signals suppresses the increase in ornithine decarboxylase (ODC) gene expression induced by the growth-promoting hormones prolactin (PRL) and growth hormone (GH). Here, we identify a molecular mechanism through which maternal separation (MS) curtails ODC expression. Our results demonstrate that the absence of specific tactile stimuli provided by the mother limits PRL-evoked stimulation of ODC biosynthesis by interfering with sn-1,2-diacylglycerol's (DAG) ability to activate protein kinase Calpha (PKCalpha) and consequently c-myc mRNA and max mRNA expression. The proteins encoded by these proto-oncogenes function as direct transactivators of the ODC gene. As ODC activity is obligatory for normal cell replication and differentiation, PKCalpha activation by DAG represents an important control point at which 'nurturing touch' regulates growth and development of the neonate. Such a mechanism can explain the maladaptive consequences of disrupting mother-infant tactile interactions as occurs in isolated premature babies. Also, it could provide a basis for developing therapeutic interventions to maximize growth potential in children failing-to-thrive despite normal maternal care. PMID:12700701

  9. Protein tyrosine phosphatase mu regulates glioblastoma cell growth and survival in vivo

    PubMed Central

    Kaur, Harpreet; Burden-Gulley, Susan M.; Phillips-Mason, Polly J.; Basilion, James P.; Sloan, Andrew E.; Brady-Kalnay, Susann M.

    2012-01-01

    Glioblastoma multiforme (GBM) is the most lethal primary brain tumor. Extensive proliferation and dispersal of GBM tumor cells within the brain limits patient survival to approximately 1 year. Hence, there is a great need for the development of better means to treat GBM. Receptor protein tyrosine phosphatase (PTP)µ is proteolytically cleaved in GBM to yield fragments that promote dispersal of GBM cells. While normal brain tissue retains expression of full-length PTPµ, low-grade human astrocytoma samples have varying amounts of full-length PTPµ and cleaved PTPµ. In the highest-grade astrocytomas (i.e., GBM), PTPµ is completely proteolyzed into fragments. We demonstrate that short hairpin RNA mediated knockdown of full-length PTPµ and PTPµ fragments reduces glioma cell growth and survival in vitro. The reduction in growth and survival following PTPµ knockdown is enhanced when cells are grown in the absence of serum, suggesting that PTPµ may regulate autocrine signaling. Furthermore, we show for the first time that reduction of PTPµ protein expression decreases the growth and survival of glioma cells in vivo using mouse xenograft flank and i.c. tumor models. Inhibitors of PTPµ could be used to reduce the growth and survival of GBM cells in the brain, representing a promising therapeutic target for GBM. PMID:22505657

  10. Regulation of phosphorus stoichiometry and growth rate of consumers: theoretical and experimental analyses with Daphnia.

    PubMed

    Shimizu, Yuichiro; Urabe, Jotaro

    2008-02-01

    Initial theories of ecological stoichiometry were based on the assumption that the mass-specific content of key nutrient elements (such as P), changes little within a consumer species. However, evidence has shown that this content changes substantially according to feeding conditions. To clarify how the specific P content (S (P)) of a consumer species depends on food conditions and relates to the growth rate, we constructed a multiple mass-balance model incorporating feeding and metabolic costs and stoichiometrically regulated releases for C and P. The validity of the model was then tested experimentally by examining the growth rates and S (P) of Daphnia pulicaria under various food conditions. The experimental observation agreed qualitatively well with the model, showing that the S (P) of consumers relates positively to growth rate at high food C:P ratios but negatively at low food C:P ratios. Thus, within a consumer species, individuals with high S (P) do not necessarily grow at high rates. The concordance in results between the model and our observation suggests that maintenance costs for both P and C are substantial regardless of food conditions and play crucial roles in determining the relationship between the S (P) and growth rate of consumers. PMID:17989999

  11. Checkpoint Kinase 2 Negatively Regulates Androgen Sensitivity and Prostate Cancer Cell Growth.

    PubMed

    Ta, Huy Q; Ivey, Melissa L; Frierson, Henry F; Conaway, Mark R; Dziegielewski, Jaroslaw; Larner, James M; Gioeli, Daniel

    2015-12-01

    Prostate cancer is the second leading cause of cancer death in American men, and curing metastatic disease remains a significant challenge. Nearly all patients with disseminated prostate cancer initially respond to androgen deprivation therapy (ADT), but virtually all patients will relapse and develop incurable castration-resistant prostate cancer (CRPC). A high-throughput RNAi screen to identify signaling pathways regulating prostate cancer cell growth led to our discovery that checkpoint kinase 2 (CHK2) knockdown dramatically increased prostate cancer growth and hypersensitized cells to low androgen levels. Mechanistic investigations revealed that the effects of CHK2 were dependent on the downstream signaling proteins CDC25C and CDK1. Moreover, CHK2 depletion increased androgen receptor (AR) transcriptional activity on androgen-regulated genes, substantiating the finding that CHK2 affects prostate cancer proliferation, partly, through the AR. Remarkably, we further show that CHK2 is a novel AR-repressed gene, suggestive of a negative feedback loop between CHK2 and AR. In addition, we provide evidence that CHK2 physically associates with the AR and that cell-cycle inhibition increased this association. Finally, IHC analysis of CHK2 in prostate cancer patient samples demonstrated a decrease in CHK2 expression in high-grade tumors. In conclusion, we propose that CHK2 is a negative regulator of androgen sensitivity and prostate cancer growth, and that CHK2 signaling is lost during prostate cancer progression to castration resistance. Thus, perturbing CHK2 signaling may offer a new therapeutic approach for sensitizing CRPC to ADT and radiation. PMID:26573794

  12. Growth Regulator Induced Movement of Photosynthetic Products Into Fruits of `Black Corinth' Grapes 1

    PubMed Central

    Weaver, Robert J.; Shindy, Wasfy; Kliewer, W. Mark

    1969-01-01

    The effect of exogenous growth regulators on movement of assimilates into flowers and young fruits of `Black Corinth' grapes was studied. Clusters were treated with growth regulator and after 0.5 hr to 5 days the leaves above the clusters were exposed to 14CO2. Control shoots received 14CO2 but no growth regulator. At harvest, counting and radioautographic techniques were used to ascertain amount and distribution of activity in clusters. Clusters were dipped in 4-CPA (4-chlorophenoxyacetic acid), GA3 (gibberellic acid), or BA (benzyladenine). All berries were heavier than controls within 3 days. Total counts in the fruits were increased by 4-CPA, and the distribution of radioactivity among the sugar, organic acid, and amino acid fractions was usually altered by all treatments. In a time series experiment, within 6 hr after treatment of fruits with GA3 there was almost an 8-fold increase in total counts relative to the control. After 12 hr there was about a 9-fold and 6-fold increase in counts in tartaric and malic acids, respectively, and in γ-aminobutyric acid, pipecolic acid, and valine increases of 56, 150, and 330%. Radioactivity in fructose was increased 70% in gibberellin-treated clusters over the controls. After 96 hr there were only about 1000 cmp per g fr wt in controls, but there were about 31,000 cpm counts in treated clusters. Treatment of clusters with gibberellin attracted less assimilates into the fruits when shoots had also been sprayed with gibberellin. Dipping portions of clusters in gibberellin increased the movement of 14C assimilates into the treated portions. Hormonal control of mobilization is discussed. PMID:16657043

  13. Dynamic Regulation of Platelet-Derived Growth Factor Receptor α Expression in Alveolar Fibroblasts during Realveolarization

    PubMed Central

    Chen, Leiling; Acciani, Thomas; Le Cras, Tim; Lutzko, Carolyn

    2012-01-01

    Although the importance of platelet-derived growth factor receptor (PDGFR)-α signaling during normal alveogenesis is known, it is unclear whether this signaling pathway can regulate realveolarization in the adult lung. During alveolar development, PDGFR-α–expressing cells induce α smooth muscle actin (α-SMA) and differentiate to interstitial myofibroblasts. Fibroblast growth factor (FGF) signaling regulates myofibroblast differentiation during alveolarization, whereas peroxisome proliferator-activated receptor (PPAR)-γ activation antagonizes myofibroblast differentiation in lung fibrosis. Using left lung pneumonectomy, the roles of FGF and PPAR-γ signaling in differentiation of myofibroblasts from PDGFR-α–positive precursors during compensatory lung growth were assessed. FGF receptor (FGFR) signaling was inhibited by conditionally activating a soluble dominant-negative FGFR2 transgene. PPAR-γ signaling was activated by administration of rosiglitazone. Changes in α-SMA and PDGFR-α protein expression were assessed in PDGFR-α–green fluorescent protein (GFP) reporter mice using immunohistochemistry, flow cytometry, and real-time PCR. Immunohistochemistry and flow cytometry demonstrated that the cell ratio and expression levels of PDGFR-α–GFP changed dynamically during alveolar regeneration and that α-SMA expression was induced in a subset of PDGFR-α–GFP cells. Expression of a dominant-negative FGFR2 and administration of rosiglitazone inhibited induction of α-SMA in PDGFR-α–positive fibroblasts and formation of new septae. Changes in gene expression of epithelial and mesenchymal signaling molecules were assessed after left lobe pneumonectomy, and results demonstrated that inhibition of FGFR2 signaling and increase in PPAR-γ signaling altered the expression of Shh, FGF, Wnt, and Bmp4, genes that are also important for epithelial–mesenchymal crosstalk during early lung development. Our data demonstrate for the first time that a comparable

  14. Regulation of insulin-like growth factor II receptors by growth hormone and insulin in rat adipocytes.

    PubMed Central

    Lönnroth, P; Assmundsson, K; Edén, S; Enberg, G; Gause, I; Hall, K; Smith, U

    1987-01-01

    The acute and long-term effects of growth hormone (GH) on the binding of insulin-like growth factor II (IGF-II) were evaluated in adipose cells from hypophysectomized rats given replacement therapy with thyroxine and hydrocortisone and in cells from their sham-operated littermates. After the cells were incubated with insulin and/or GH, the recycling of IGF-II receptors was metabolically inhibited by treating the cells with KCN. IGF-II binding was 100 +/- 20% higher in cells from GH-deficient animals when compared with sham-operated controls. These GH-deficient cells also showed an increased sensitivity for insulin as compared with control cells (the EC50 for insulin was 0.06 ng/ml in GH-deficient cells and 0.3 ng/ml in control cells). However, the maximal incremental effect of insulin on IGF-II binding was reduced approximately 27% by hypophysectomy. GH added to the incubation medium increased the number of IGF-II binding sites by 100 +/- 18% in cells from hypophysectomized animals. This increase was rapidly induced (t1/2, approximately 10 min), but the time course was slower than that for the stimulatory effect of insulin. Half-maximal effect of GH on IGF-II binding was obtained at approximately equal to 10 ng/ml. Thus, GH added in vitro exerted a rapid insulin-like effect on the number of IGF-II receptors. GH also appears to play a regulating role for maintaining the cellular number of IGF-II receptors and, in addition, modulates the stimulatory effect of insulin on IGF-II binding. PMID:2954159

  15. Joint action of Beauveria bassiana and the insect growth regulators diflubenzuron and novaluron, on the migratory locust, Locusta migratoria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beauveria bassiana (Balsamo) Vuillemin and sublethal concentrations of the insect growth regulators (IGR) diflubenzuron and novaluron were applied simultaneously and sequentially to second instar Locusta migratoria migratorioides (Sauss.) to determine the interaction between these materials and an e...

  16. SYNTHESIS OF HAPTENS AND POTENTIAL RADIOLIGANDS AND DEVELOPMENT OF ANTIBODIES TO INSECT GROWTH REGULATORS DIFLUBENZURON AND BAY SIR 8514

    EPA Science Inventory

    A variety of synthetic approaches were undertaken, leading to potential haptens and radioligands for the benzoylphenylurea insect growth regulators diflubenzuron and BAY SIR 8514. One successful approach involved derivatization of the aniline nitrogen by ethyl 4-bromobutyrate fol...

  17. BRCA1 proteins regulate growth of ovarian cancer cells by tethering Ubc9

    PubMed Central

    Qin, Yunlong; Xu, Jingyao; Aysola, Kartik; Oprea, Gabriela; Reddy, Avinash; Matthews, Roland; Okoli, Joel; Cantor, Alan; Grizzle, William E; Partridge, Edward E; Reddy, E Shyam P; Landen, Charles; Rao, Veena N

    2012-01-01

    Mutation in the BRCA1 gene is associated with increased risk for hereditary breast and ovarian cancers. In sporadic ovarian tumors, BRCA1 dysfunction is thought to be common. BRCA1 is a nuclear-cytoplasm shuttling protein. Our group has previously reported that BRCA1 proteins, unlike K109R and cancer-predisposing mutant C61G BRCA1 proteins, bind the sole SUMO E2-conjugating enzyme Ubc9. In this study, we examined the result of altered Ubc9 binding and knockdown on the sub-cellular localization and growth inhibitory function of BRCA1 proteins in ovarian cancer cells. Using live imaging of YFP, RFP-tagged BRCA1 and BRCA1a proteins, our results show enhanced cytoplasmic localization of K109R and C61G mutant BRCA1 proteins in ES-2, NIHOVCAR3 and UWB 1.289 ovarian cancer cells. Down-regulation of Ubc9 in ovarian cancer cells using Ubc9 siRNA resulted in cytoplasmic localization of BRCA1 and BRCA1a proteins. These mutant BRCA1a proteins were impaired in their capacity to inhibit growth of ES-2 ovarian cancer cells. Several ovarian cancer cells, including a BRCA1-null ovarian cancer cell line, showed higher levels of expression of Ubc9. This is the first study demonstrating the physiological link between loss of Ubc9 binding and loss of growth suppression of disease-associated mutant BRCA1a proteins in ovarian cancer cells. BRCA1, by turning off or on Ubc9 binding, regulates growth of ovarian cancers. PMID:22957306

  18. Origins of Small Volcanic Cones on Mars

    NASA Technical Reports Server (NTRS)

    Fagents, S. A.; Pace, K.; Greeley, R.

    2002-01-01

    Studies of volcanic cones identified in the MGS data indicate a range of possible origins, from primary vent constructs (cinder cones, tuff cones) to rootless cones formed by lava-ice interaction. Additional information is contained in the original extended abstract.

  19. MYC Regulation of Cell Growth through Control of Transcription by RNA Polymerases I and III

    PubMed Central

    Campbell, Kirsteen J.; White, Robert J.

    2014-01-01

    MYC’s tumorigenic potential involves increased ribosome biogenesis and translational capacity, which supply the cell with protein required for enhanced cell growth and subsequent cell division. In addition to activation of protein-encoding genes transcribed by RNA polymerase II, MYC must stimulate transcription by RNA polymerase I and RNA polymerase III to meet this synthetic demand. In the past decade our knowledge of the mechanisms and importance of MYC regulation of RNA polymerases I and III has flourished. Here we discuss MYC’s influence on transcription by these “odd” RNA polymerases and the physiological impact of this regulation is evaluated with relevance to cancer development and treatment. PMID:24789877

  20. Adiponectin Regulates Vascular Endothelial Growth Factor-C Expression in Macrophages via Syk-ERK Pathway

    PubMed Central

    Hu, Di; Fukuhara, Atsunori; Miyata, Yugo; Yokoyama, Chieko; Otsuki, Michio; Kihara, Shinji; Shimomura, Iichiro

    2013-01-01

    Adiponectin is exclusively expressed in adipose tissues and exhibits protective effects against cardiovascular and metabolic diseases. It enhances AMP-activated kinase (AMPK) and peroxisome proliferator-activated receptor α (PPARα) signaling in the liver and skeletal muscles, however, its signaling pathways in macrophages remain to be elucidated. Here, we show that adiponectin upregulated the expression of vascular endothelial growth factor (VEGF)-C, and induced phosphorylation of extracellular signal-regulated kinase (ERK) in macrophages. Inhibition of Syk abrogated adiponectin-induced VEGF-C expression and ERK phosphorylation. Furthermore, inhibition of ERK blocked the induction of VEGF-C gene. Inhibition of Syk, but not that of ERK, abrogated adiponectin-induced expression of cyclooxygenase (COX)-2, tissue inhibitor of metalloproteinase (TIMP)-1, and interleukin (IL)-6. These results indicate that adiponectin regulates VEGF-C expression via Syk-ERK pathway in macrophages. PMID:23424645

  1. CYLD negatively regulates transforming growth factor-β-signalling via deubiquitinating Akt

    PubMed Central

    Lim, Jae Hyang; Jono, Hirofumi; Komatsu, Kensei; Woo, Chang-Hoon; Lee, Jiyun; Miyata, Masanori; Matsuno, Takashi; Xu, Xiangbin; Huang, Yuxian; Zhang, Wenhong; Park, Soo Hyun; Kim, Yu-Il; Choi, Yoo-Duk; Shen, Huahao; Heo, Kyung-Sun; Xu, Haodong; Bourne, Patricia; Koga, Tomoaki; Xu, Haidong; Yan, Chen; Wang, Binghe; Chen, Lin-Feng; Feng, Xin-Hua; Li, Jian-Dong

    2012-01-01

    Lung injury, whether induced by infection or caustic chemicals, initiates a series of complex wound-healing responses. If uncontrolled, these responses may lead to fibrotic lung diseases and loss of function. Thus, resolution of lung injury must be tightly regulated. The key regulatory proteins required for tightly controlling the resolution of lung injury have yet to be identified. Here we show that loss of deubiquitinase CYLD led to the development of lung fibrosis in mice after infection with Streptococcus pneumoniae. CYLD inhibited transforming growth factor-β-signalling and prevented lung fibrosis by decreasing the stability of Smad3 in an E3 ligase carboxy terminus of Hsc70-interacting protein-dependent manner. Moreover, CYLD decreases Smad3 stability by deubiquitinating K63-polyubiquitinated Akt. Together, our results unveil a role for CYLD in tightly regulating the resolution of lung injury and preventing fibrosis by deubiquitinating Akt. These studies may help develop new therapeutic strategies for preventing lung fibrosis. PMID:22491319

  2. Synthesis of octadecyl esters of histidine-containing tripeptides as potential regulators of plant growth

    SciTech Connect

    Ogrel, A.A.; Zvonkova, E.N.; Gafurov, R.G.

    1995-08-01

    Octadecyl esters of dipeptides and tripeptides of the type Phe-His, Val-His, Phe-Val-His and Val-Phe-His were synthesized using different methods. The minimum energy conformations of these peptides were calculated with computer minimization programs and compared with those of paclobutrazol, a well-known regulator of plant growth. It was demonstrated that the elongation of the peptide chain leads to a higher topochemical correspondence between paclobutrazol and the peptide derivatives than between paclobutrazol and amino acid derivatives. 9 refs., 2 figs., 3 tabs.

  3. Downward regulation of photosynthesis and growth at high CO sub 2 levels

    SciTech Connect

    Idso, S.B.; Kimball, B.A. )

    1991-07-01

    Numerous photosynthesis and growth measurements of sour orange (Citrus aurantium L.) trees maintained in ambient air and air enriched with an extra 300 microliters per liter of Co{sub 2} have revealed the Co{sub 2}-enriched trees to have consistently sequestered approximately 2.8 times more carbon than the control trees over a period of three full years. Under field conditions in the natural environment, plants may not experience the downward regulation of photosynthetic capacity typically observed in long-term CO{sub 2} enrichment experiments with plants growing in pots.

  4. Stability and Hopf bifurcation for a regulated logistic growth model with discrete and distributed delays

    NASA Astrophysics Data System (ADS)

    Fang, Shengle; Jiang, Minghui

    2009-12-01

    In this paper, we investigate the stability and Hopf bifurcation of a new regulated logistic growth with discrete and distributed delays. By choosing the discrete delay τ as a bifurcation parameter, we prove that the system is locally asymptotically stable in a range of the delay and Hopf bifurcation occurs as τ crosses a critical value. Furthermore, explicit algorithm for determining the direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions is derived by normal form theorem and center manifold argument. Finally, an illustrative example is also given to support the theoretical results.

  5. Design and synthesis of benzoylphenylureas with fluorinated substituents on the aniline ring as insect growth regulators.

    PubMed

    Sun, Ranfeng; Liu, Yuxiu; Zhang, Yonglin; Xiong, Lixia; Wang, Qingmin

    2011-03-23

    Enormous numbers of synthetic fluorine-containing compounds have been widely used in a variety of fields, especially in drug and pesticide design. To find novel insect growth regulators, a series of benzoylphenylureas with fluorinated substituents were designed and synthesized. The results of larvicidal activities of those novel fluoro-substituted benzoylphenylureas against oriental armyworm and mosquito revealed that most compounds exhibited excellent activities. It is worth mentioning that compounds 3 and 6 exhibited higher activities against oriental armyworm and mosquito than commercial Hexaflumuron. It can be further seen that the insecticidal activities would increase significantly by introducing fluorinated substituents into the structure of the designed benzoylphenylureas. PMID:21366291

  6. Effect of plant growth regulators on fatty acids composition in Jatropha curcas L. callus culture.

    PubMed

    Hernandez, Ludwi Rodríguez; Mendiola, Martha A Rodríguez; Castro, Carlos Arias; Gutiérrez-Miceli, Federico A

    2015-01-01

    The influence of Naphtaleneacetic acid (NAA) and 6-Benzylaminopurine (BAP) on callus formation, its morphology and fatty acids profile were examined from Jatropha curcas L. Embryo from seeds of J. curcas L. were sown in Murashige and skoog (MS) medium with NAA and BAP. All treatments induced callus formation, however callus morphology was different in most of the treatments. Higher callus biomass was presented with 1.0 NAA + 0.5 BAP mg/L. Plant growth regulators modifies the fatty acids profile in callus of J. curcas L. BAP was induced linoleic and linolenic acids. PMID:25757437

  7. An approach for the conquest of the sugi pollinosis using plant growth regulation.

    PubMed

    Honma, Tamaki

    2003-06-01

    The sugi (Cryptomeria japonica) pollinosis becomes representative allergic disease in early spring in Japan. However, effective treatment for the sugi pollinosis and countermeasure against pollen of C. japonica at its source have not been developed in a practical sense. In this paper, the research aiming to prevent dispersion of pollen of the C. japonica is introduced on application and practical application to the field from the laboratory using the growth regulation of the plant. We found that formation of male flower bud in C. japonica could be suppressed by TNE, since the 3 beta-hydroxylase is inhibited by the action of Trinexysapacethyl, TNE. PMID:12897460

  8. Cell Cycle-Independent Phospho-Regulation of Fkh2 during Hyphal Growth Regulates Candida albicans Pathogenesis

    PubMed Central

    Greig, Jamie A.; Sudbery, Ian M.; Richardson, Jonathan P.; Naglik, Julian R.; Wang, Yue; Sudbery, Peter E.

    2015-01-01

    The opportunistic human fungal pathogen, Candida albicans, undergoes morphological and transcriptional adaptation in the switch from commensalism to pathogenicity. Although previous gene-knockout studies have identified many factors involved in this transformation, it remains unclear how these factors are regulated to coordinate the switch. Investigating morphogenetic control by post-translational phosphorylation has generated important regulatory insights into this process, especially focusing on coordinated control by the cyclin-dependent kinase Cdc28. Here we have identified the Fkh2 transcription factor as a regulatory target of both Cdc28 and the cell wall biosynthesis kinase Cbk1, in a role distinct from its conserved function in cell cycle progression. In stationary phase yeast cells 2D gel electrophoresis shows that there is a diverse pool of Fkh2 phospho-isoforms. For a short window on hyphal induction, far before START in the cell cycle, the phosphorylation profile is transformed before reverting to the yeast profile. This transformation does not occur when stationary phase cells are reinoculated into fresh medium supporting yeast growth. Mass spectrometry and mutational analyses identified residues phosphorylated by Cdc28 and Cbk1. Substitution of these residues with non-phosphorylatable alanine altered the yeast phosphorylation profile and abrogated the characteristic transformation to the hyphal profile. Transcript profiling of the phosphorylation site mutant revealed that the hyphal phosphorylation profile is required for the expression of genes involved in pathogenesis, host interaction and biofilm formation. We confirmed that these changes in gene expression resulted in corresponding defects in pathogenic processes. Furthermore, we identified that Fkh2 interacts with the chromatin modifier Pob3 in a phosphorylation-dependent manner, thereby providing a possible mechanism by which the phosphorylation of Fkh2 regulates its specificity. Thus, we have

  9. Glucose and glucosamine regulate growth factor gene expression in vascular smooth muscle cells.

    PubMed Central

    McClain, D A; Paterson, A J; Roos, M D; Wei, X; Kudlow, J E

    1992-01-01

    We have investigated the regulation of the expression of two growth factors found in vascular smooth muscle, transforming growth factor alpha (TGF alpha) and basic fibroblast growth factor (bFGF). Cells cultured in medium containing 30 mM glucose exhibited a 2-fold increase in TGF alpha mRNA and a 3-fold increase in bFGF mRNA compared with cells grown in normal (5.5 mM) glucose. Glucosamine was more potent than glucose, leading to a 6-fold increase in TGF alpha mRNA. TGF alpha protein levels were also increased by glucosamine treatment, and the predominant species present was the membrane-bound precursor form of TGF alpha. To examine further the regulation of growth factors by sugars, cultured rat aortic smooth muscle cells were transfected with a plasmid construct consisting of a 1.2-kilobase-pair fragment of the TGF alpha promoter linked to a luciferase reporter gene. Increasing the concentration of glucose in the culture medium from 5.5 mM to 30 mM led to a rapid, 1.7-fold increase in the activity of the TGF alpha promoter. Glucosamine was much more potent than glucose in this stimulation, with 2 mM glucosamine causing a 12-fold increase in TGF alpha promoter activity. Insulin had no effect on luciferase activity in either the presence or the absence of added sugars. The glucose response element of the TGF alpha gene maps to a 130-base-pair segment that includes three potential binding sites for the transcription factor Sp1. We conclude that high glucose concentrations such as are reached in diabetes mellitus can stimulate the transcription of the genes for growth factors in vascular smooth muscle cells. This signaling pathway apparently involves the metabolism of glucose to glucosamine. This effect could be representative of nutritional regulation of a family of genes and could contribute to the toxicity of hyperglycemia and the vascular complications of diabetes. Images PMID:1518840

  10. Flower synchrony, growth and yield enhancement of small type bitter gourd (Momordica charantia L.) through plant growth regulators and NPK fertilization.

    PubMed

    Mia, Baset M A; Islam, Md Serajul; Miah, Md Yunus; Das, M R; Khan, H I

    2014-02-01

    Assessment of growth regulator and NPK fertilization effects are important tools for flower stimulation and yield improvement in cucurbits. This investigation demonstrates the comparative male-female flower induction and fruit yield of small sized bitter gourd treated with NPK fertilizers and plant growth regulators. Namely, two experiments having three replicates were conducted in a Randomized Complete Block Design (RCBD) with NPK fertilization and plant growth regulators-GA3, NAA and Ethophon application on small sized bitter gourd-genotype BG5 at the research field of the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU). In experiment 1, different doses of NPK fertilizers comprised of 10 treatments and in that of experiment 2, different levels of plant growth regulators indicated 10 treatments. The results indicated that application of different doses of NPK fertilizer and plant growth regulators significantly (< or = 0.05) influenced over the flower initiation and fruit setting. The application of N90-P45-K60 fertilizer along with Ethophon spraying resulted in the better yield of small sized bitter gourd. PMID:24897796

  11. Long Non-coding RNAs (LncRNA) Regulated by Transforming Growth Factor (TGF) β

    PubMed Central

    Richards, Edward J.; Zhang, Gu; Li, Zhu-Peng; Permuth-Wey, Jennifer; Challa, Sridevi; Li, Yajuan; Kong, William; Dan, Su; Bui, Marilyn M.; Coppola, Domenico; Mao, Wei-Min; Sellers, Thomas A.; Cheng, Jin Q.

    2015-01-01

    Long noncoding RNAs (lncRNAs) are emerging as key regulators in various biological processes. Epithelial-to-mesenchymal transition (EMT) is a developmental process hijacked by tumor cells to depart from the primary tumor site, invade surrounding tissue, and establish distant metastases. Transforming growth factor β (TGFβ) signaling has been shown to be a major inducer of EMT and to facilitate breast cancer metastasis. However, the role of lncRNAs in this process remains largely unknown. Here we report a genome-wide lncRNA profile in mouse mammary epithelial NMuMG cells upon TGFβ induction of EMT. Among 10,802 lncRNAs profiled, over 600 were up-regulated and down-regulated during the EMT, respectively. Furthermore, we identify that lncRNA-HIT (HOXA transcript induced by TGFβ) mediates TGFβ function, i.e. depletion of lncRNA-HIT inhibits TGFβ-induced migration, invasion, and EMT in NMuMG. LncRNA-HIT is also significantly elevated in the highly metastatic 4T1 cells. Knockdown of lncRNA-HIT in 4T1 results in decrease of cell migration, invasion, tumor growth, and metastasis. E-cadherin was identified as a major target of lncRNA-HIT. Moreover, lncRNA-HIT is conserved in humans and elevated expression associates with more invasive human primary breast carcinoma. Collectively, these data suggest that a subset of lncRNAs such as lncRNA-HIT play a significant role in regulation of EMT and breast cancer invasion and metastasis, and could be potential therapeutic targets in breast cancers. PMID:25605728

  12. PACT is a negative regulator of p53 and essential for cell growth and embryonic development.

    PubMed

    Li, Li; Deng, Binwei; Xing, Guichun; Teng, Yan; Tian, Chunyan; Cheng, Xuan; Yin, Xiushan; Yang, Juntao; Gao, Xue; Zhu, Yunping; Sun, Qihong; Zhang, Lingqiang; Yang, Xiao; He, Fuchu

    2007-05-01

    The tumor suppressor p53 regulates cell cycle progression and apoptosis in response to various types of stress, whereas excess p53 activity creates unwanted effects. Tight regulation of p53 is essential for maintaining normal cell growth. p53-associated cellular protein-testes derived (PACT, also known as P2P-R, RBBP6) is a 250-kDa Ring finger-containing protein that can directly bind to p53. PACT is highly up-regulated in esophageal cancer and may be a promising target for immunotherapy. However, the physiological role of the PACT-p53 interaction remains largely unclear. Here, we demonstrate that the disruption of PACT in mice leads to early embryonic lethality before embryonic day 7.5 (E7.5), accompanied by an accumulation of p53 and widespread apoptosis. p53-null mutation partially rescues the lethality phenotype and prolonged survival to E11.5. Endogenous PACT can interact with Hdm2 and enhance Hdm2-mediated ubiquitination and degradation of p53 as a result of the increase of the p53-Hdm2 affinity. Consequently, PACT represses p53-dependent gene transcription. Knockdown of PACT significantly attenuates the p53-Hdm2 interaction, reduces p53 polyubiquitination, and enhances p53 accumulation, leading to both apoptosis and cell growth retardation. Taken together, our data demonstrate that the PACT-p53 interaction plays a critical role in embryonic development and tumorigenesis and identify PACT as a member of negative regulators of p53. PMID:17470788

  13. Androgen Receptor Coactivators in Regulation of Growth and Differentiation in Prostate Cancer.

    PubMed

    Culig, Zoran

    2016-02-01

    Androgen receptor (AR) is a key factor in regulation of growth and differentiation in normal and malignant prostate. Endocrine therapies for prostate cancer include inhibition of androgen production either by analogs of luteinizing hormone releasing hormone or abiraterone acetate and/or use of anti-androgens such as hydroxyflutamide, bicalutamide, and enzalutamide. Castration therapy-resistant cancer develops inevitably in patients who undergo treatment. AR coactivators are proteins which interact with one or more regions of the AR thus enhancing its function. Although several functions of AR coactivators may be redundant, specific functions have been identified and analyzed. The p160 group of coactivators, SRC-1, -2, and -3 not only potentiate the activation of the AR, but are also implicated in potentiation of function of insulin-like growth factor-I and activation of the Akt pathway. Transcriptional integrators p300 and CBP are up-regulated by androgen ablation and may influence antagonist/agonist balance of non-steroidal anti-androgens. A therapy approach designed to target p300 in prostate cancer revealed its role in regulation of proliferation of migration of androgen-sensitive and -insensitive prostate cancer cells. Coactivators p300 and SRC-1 are required for AR activation by interleukin-6 (IL-6), a cytokine that is overexpressed in castration therapy-resistant prostate cancer. Some coactivators, such as Vav3, are involved in regulation of transcriptional activity of truncated AR, which emerge during endocrine thrapy. Stimulation of cellular migration and invasion by AR coactivators has also been described. Translational studies with aim to introduce anti-AR coactivator therapy have not been successfully implemented in the clinic so far. PMID:26201947

  14. Cytokinins negatively regulate the root iron uptake machinery in Arabidopsis through a growth-dependent pathway.

    PubMed

    Séguéla, Mathilde; Briat, Jean-François; Vert, Grégory; Curie, Catherine

    2008-07-01

    Plants display a number of biochemical and developmental responses to low iron availability in order to increase iron uptake from the soil. The ferric-chelate reductase FRO2 and the ferrous iron transporter IRT1 control iron entry from the soil into the root epidermis. In Arabidopsis, expression of IRT1 and FRO2 is tightly controlled to maintain iron homeostasis, and involves local and long-distance signals, as well as transcriptional and post-transcriptional events. FIT encodes a putative basic helix-loop-helix (bHLH) transcription factor that regulates iron uptake responses in Arabidopsis. Here, we uncover a new regulation of the root iron uptake genes. We show that IRT1, FRO2 and FIT are repressed by the exogenous addition of cytokinins (CKs), and that this repression acts at the level of transcript accumulation, and depends on the AHK3 and CRE1 CK receptors. The CKs and iron-deficiency signals act through distinct pathways to regulate the soil iron uptake genes, as (i) CK repression is independent of the iron status, (ii) IRT1 and FRO2 downregulation is unchanged in a fit loss-of-function mutant, indicating that FIT does not mediate CK repression, and (iii) the iron-regulated genes AtNRAMP3 and AtNRAMP4 are not downregulated by CKs. We show that root growth-inhibitory conditions, such as abiotic stresses (mannitol, NaCl) and hormonal treatments (auxin, abscissic acid), repress the iron starvation response genes. We propose that CKs control the root iron uptake machinery through a root growth dependent pathway in order to adapt nutrient uptake to the demand of the plant. PMID:18397377

  15. Minireview: Roles of Fibroblast Growth Factors 19 and 21 in Metabolic Regulation and Chronic Diseases.

    PubMed

    Zhang, Fangfang; Yu, Lechu; Lin, Xiufei; Cheng, Peng; He, Luqing; Li, Xiaokun; Lu, Xuemian; Tan, Yi; Yang, Hong; Cai, Lu; Zhang, Chi

    2015-10-01

    Fibroblast growth factor (FGF)19 and FGF21 are hormones that regulate metabolic processes particularly during feeding or starvation, thus ultimately influencing energy production. FGF19 is secreted by the intestines during feeding and negatively regulates bile acid synthesis and secretion, whereas FGF21 is produced in the liver during fasting and plays a crucial role in regulating glucose and lipid metabolism, as well as maintaining energy homeostasis. FGF19 and FGF21 are regarded as late-acting hormones because their functions are only used after insulin and glucagon have completed their actions. Although FGF19 and FGF21 are activated under different conditions, they show extensively functional overlap in terms of improving glucose tolerance, insulin sensitivity, weight loss, and lipid, and energy metabolism, particularly in pathological conditions such as diabetes, obesity, metabolic syndrome, and cardiovascular and renal diseases. Most patients with these metabolic diseases exhibit reduced serum FGF19 levels, which might contribute to its etiology. In addition, the simultaneous increase in serum FGF21 levels is likely a compensatory response to reduced FGF19 levels, and the 2 proteins concertedly maintain metabolic homeostasis. Here, we review the physiological and pharmacological cross talk between FGF19 and FGF21 in relation to the regulation of endocrine metabolism and various chronic diseases. PMID:26308386

  16. Synergistic interaction between insulin-like growth factors-I and -II in central regulation of pulsatile growth hormone secretion.

    PubMed

    Harel, Z; Tannenbaum, G S

    1992-08-01

    Insulin-like growth factor (IGF)-I and -II peptides, receptors, mRNAs, and binding proteins are widely distributed in the central nervous system (CNS), yet their physiological role in the brain remains largely unknown. While earlier in vivo studies in the rat suggested that IGF-I may participate in feedback regulation of GH secretion at a CNS level, the preparations used were only partially pure. The recent availability of purified recombinant IGF-I and -II peptides prompted us to reexamine the involvement of the IGFs in vivo in central regulation of pulsatile GH secretion. Five groups of free-moving adult male rats bearing chronic intracerebroventricular (icv) and intracardiac venous cannulae were icv administered IGF-I (in doses of 0.5, 2, 3, and 10 micrograms) or the acid-saline vehicle; an additional group received 1 microgram of the potent IGF-I analog, long R3 IGF-I. Spontaneous 6-h plasma GH secretory profiles were obtained from all groups. Vehicle-injected control animals exhibited the typical pulsatile pattern of GH secretion, with most peak GH values above 150 ng/ml and trough levels below 1.2 ng/ml. Central administration of IGF-I alone or long R3 IGF-I at all doses tested failed to alter the pulsatile pattern of GH release; there were no significant differences in GH peak amplitude, GH trough level, GH interpeak interval, or mean 6-h plasma GH level compared to those in vehicle-injected controls. In a second study, designed to determine the effects of central administration of IGF-I and IGF-II, in combination, icv injection of 1 microgram IGF-I and 1 microgram IGF-II resulted in a marked suppression in the amplitude of spontaneous GH secretory bursts approximately 3 h after injection; both GH pulse amplitude (43.5 +/- 5.6 vs. 130.6 +/- 14.6 ng/ml; P less than 0.001) and mean plasma GH level (16.3 +/- 1.9 vs. 35.2 +/- 1.8 ng/ml; P less than 0.001) were severely reduced 3-6 h after injection compared to those in vehicle-injected controls. These results

  17. Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth

    PubMed Central

    Gasperini, Debora; Chételat, Aurore; Acosta, Ivan F.; Goossens, Jonas; Pauwels, Laurens; Goossens, Alain; Dreos, René; Alfonso, Esteban; Farmer, Edward E.

    2015-01-01

    Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA) signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots. Regulatory JA signalling components were then manipulated to delineate their relative impacts on root growth. The new transcription factor mutant myc2-322B was isolated. In vitro transcription assays and whole-plant approaches revealed that myc2-322B is a dosage-dependent gain-of-function mutant that can amplify JA growth responses. Moreover, myc2-322B displayed extreme hypersensitivity to JA that totally suppressed root elongation. The mutation weakly reduced root growth in undamaged plants but, when the upstream negative regulator NINJA was genetically removed, myc2-322B powerfully repressed root growth through its effects on cell division and cell elongation. Furthermore, in a JA-deficient mutant background, ninja1 myc2-322B still repressed root elongation, indicating that it is possible to generate JA-responses in the absence of JA. We show that NINJA forms a broadly expressed regulatory layer that is required to inhibit JA signalling in the apex of roots grown under basal conditions. By contrast, MYC2, MYC3 and MYC4 displayed cell layer-specific localisations and MYC3 and MYC4 were expressed in mutually exclusive regions. In nature, growing roots are likely subjected to constant mechanical stress during soil penetration that could lead to JA production and subsequent detrimental effects on growth. Our data reveal how distinct negative regulatory layers, including both NINJA-dependent and -independent mechanisms, restrain JA responses to allow normal root growth. Mechanistic insights from this work underline the importance of mapping JA signalling components to specific

  18. Overview of Genomic Insights into Chicken Growth Traits Based on Genome-Wide Association Study and microRNA Regulation

    PubMed Central

    Xu, Zhenqiang; Nie, Qinghua; Zhang, Xiquan

    2013-01-01

    Over the two past decades, a significant number of studies have observed animal growth traits to examine animal genetic mechanisms due to their ease of measurement and high heritability. Chicken which has a significant impact on fundamental biology is a major source of protein worldwide, making it an ideal model for examining animal growth trait development. The genetic mechanisms of chicken growth traits have been studied using quantitative trait loci mapping through genome-scan and candidate gene approaches, genome-wide association studies (GWAS), comparative genomic strategies, microRNA (miRNA) regulation of growth development analysis, and epigenomic analysis. This review focuses on chicken GWAS and miRNA regulation of growth traits. Several recently published GWAS reports showed that most genome-wide significant single nucleotide polymorphisms are located on chromosomes 1 and 4 in chickens. Chicken growth, particularly skeletal muscle growth and development, is greatly regulated by miRNA. Using dwarf and normal chickens, let-7b was found to be involved in determining chicken dwarf phenotypes by regulating growth hormone receptor gene expression. PMID:24082823

  19. Harzianolide, a novel plant growth regulator and systemic resistance elicitor from Trichoderma harzianum.

    PubMed

    Cai, Feng; Yu, Guanghui; Wang, Ping; Wei, Zhong; Fu, Lin; Shen, Qirong; Chen, Wei

    2013-12-01

    A detailed understanding of the effect of natural products on plant growth and protection will underpin new product development for plant production. The isolation and characterization of a known secondary metabolite named harzianolide from Trichoderma harzianum strain SQR-T037 were described, and the bioactivity of the purified compound as well as the crude metabolite extract in plant growth promotion and systemic resistance induction was investigated in this study. The results showed that harzianolide significantly promoted tomato seedling growth by up to 2.5-fold (dry weight) at a concentration of 0.1 ppm compared with the control. The result of root scan suggested that Trichoderma secondary metabolites may influence the early stages of plant growth through better root development for the enhancement of root length and tips. Both of the purified harzianolide and crude metabolite extract increased the activity of some defense-related enzymes to response to oxidative stress. Examination of six defense-related gene expression by real-time reverse transcription-PCR analysis revealed that harzianolide induces the expression of genes involved in the salicylic acid (PR1 and GLU) and jasmonate/ethylene (JERF3) signaling pathways while crude metabolite extract inhibited some gene expression (CHI-II and PGIP) related to basal defense in tomato plants. Further experiment showed that a subsequent challenge of harzianolide-pretreated plants with the pathogen Sclerotinia sclerotiorum resulted in higher systemic resistance by the reduction of lesion size. These results indicate that secondary metabolites of Trichoderma spp., like harzianolide, may play a novel role in both plant growth regulation and plant defense responses. PMID:24080397

  20. MARCKS Regulates Growth, Radiation Sensitivity and is a Novel Prognostic Factor for Glioma

    PubMed Central

    Jarboe, John S.; Anderson, Joshua C.; Duarte, Christine W.; Mehta, Tapan; Nowsheen, Somaira; Hicks, Patricia H.; Whitley, Alexander C.; Rohrbach, Timothy D.; McCubrey, Raymond O.; Chiu, Sherard; Burleson, Tamara M.; Bonner, James A.; Gillespie, G. Yancey; Yang, Eddy S.; Willey, Christopher D.

    2013-01-01

    Purpose This study assessed whether Myristoylated Alanine Rich C-Kinase Substrate (MARCKS) can regulate glioblastoma (GBM) growth, radiation sensitivity and clinical outcome. Experimental Design MARCKS protein levels were analyzed in five GBM explant cell lines and eight patient-derived xenograft tumors by immunoblot, and these levels were correlated to proliferation rates and intracranial growth rates, respectively. Manipulation of MARCKS protein levels was assessed by lentiviral-mediated shRNA knockdown in the U251 cell line and MARCKS over-expression in the U87 cell line. The effect of manipulation of MARCKS on proliferation, radiation sensitivity and senescence was assessed. MARCKS gene expression was correlated with survival outcomes in the Repository of Molecular Brain Neoplasia Data (REMBRANDT) Database and The Cancer Genome Atlas (TCGA). Results MARCKS protein expression was inversely correlated with GBM proliferation and intracranial xenograft growth rates. Genetic silencing of MARCKS promoted GBM proliferation and radiation resistance, while MARCKS overexpression greatly reduced GBM growth potential and induced senescence. We found MARCKS gene expression to be directly correlated with survival in both the REMBRANDT and TCGA databases. Specifically, patients with high MARCKS expressing tumors of the Proneural molecular subtype had significantly increased survival rates. This effect was most pronounced in tumors with unmethylated O6-methylguanine DNA methyltransferase (MGMT) promoters, a traditionally poor prognostic factor. Conclusions MARCKS levels impact GBM growth and radiation sensitivity. High MARCKS expressing GBM tumors are associated with improved survival, particularly with unmethylated MGMT promoters. These findings suggest the use of MARCKS as a novel target and biomarker for prognosis in the Proneural subtype of GBM. PMID:22619307

  1. Rictor/TORC2 regulates fat metabolism, feeding, growth, and life span in Caenorhabditis elegans.

    PubMed

    Soukas, Alexander A; Kane, Elizabeth A; Carr, Christopher E; Melo, Justine A; Ruvkun, Gary

    2009-02-15

    Rictor is a component of the target of rapamycin complex 2 (TORC2). While TORC2 has been implicated in insulin and other growth factor signaling pathways, the key inputs and outputs of this kinase complex remain unknown. We identified mutations in the Caenorhabditis elegans homolog of rictor in a forward genetic screen for increased body fat. Despite high body fat, rictor mutants are developmentally delayed, small in body size, lay an attenuated brood, and are short-lived, indicating that Rictor plays a critical role in appropriately partitioning calories between long-term energy stores and vital organismal processes. Rictor is also necessary to maintain normal feeding on nutrient-rich food sources. In contrast to wild-type animals, which grow more rapidly on nutrient-rich bacterial strains, rictor mutants display even slower growth, a further reduced body size, decreased energy expenditure, and a dramatically extended life span, apparently through inappropriate, decreased consumption of nutrient-rich food. Rictor acts directly in the intestine to regulate fat mass and whole-animal growth. Further, the high-fat phenotype of rictor mutants is genetically dependent on akt-1, akt-2, and serum and glucocorticoid-induced kinase-1 (sgk-1). Alternatively, the life span, growth, and reproductive phenotypes of rictor mutants are mediated predominantly by sgk-1. These data indicate that Rictor/TORC2 is a nutrient-sensitive complex with outputs to AKT and SGK to modulate the assessment of food quality and signal to fat metabolism, growth, feeding behavior, reproduction, and life span. PMID:19240135

  2. Differential Expression of Cell Cycle Regulators During Hyperplastic and Hypertrophic Growth of Broiler Subcutaneous Adipose Tissue.

    PubMed

    Zhang, J; Suh, Y; Choi, Y M; Chen, P R; Davis, M E; Lee, K

    2015-10-01

    Hyperplastic growth and hypertrophic growth within adipose tissue is tightly associated with cell cycle activity. In this study, CCNG2 and CDKN2C were found to be correlated with cell cycle inhibition during fat cell differentiation, whereas CCND3, CCNA1, and ANAPC5 were positively associated with cell cycle activity during fat cell proliferation after selection based on GEO datasets available on the NCBI website. The findings were validated through comparison of expressions of these genes among different tissues/fractions in broiler chickens and time points during primary cell culture using quantitative real-time PCR. Development of broiler subcutaneous adipose tissue was investigated on embryonic days 15 and 17 and on post-hatch days 0, 5, 11, and 33 using H&E staining and PCNA immunostaining with DAPI counter stain. In addition, mRNA expressions of five cell cycle regulators as well as precursor cell and adipocyte markers were measured at those time points. The results suggest that cellular proliferation activity decreased as the fat pad grows, but a population of precursor cells seemed to be maintained until post-hatch day 5 despite increasing differentiation activity. Hypertrophic growth gradually intensified despite a slight cessation on post-hatch day 0 due to increased energy expenditure during hatching and delayed food access. From post-hatch day 5 to day 11, most of the precursor cells may become differentiated. After post-hatch day 11, hyperplastic growth seemed to slow, while hypertrophic growth may become dominant. This study provides further understanding about broiler fat tissue development which is imperative for effective control of fat deposition. PMID:26017028

  3. Regulation of adult cardiocyte growth: effects of active and passive mechanical loading

    NASA Technical Reports Server (NTRS)

    Decker, M. L.; Janes, D. M.; Barclay, M. M.; Harger, L.; Decker, R. S.

    1997-01-01

    Fluctuations in hemodynamic load have been documented to modulate contractile protein turnover and myofibrillar structure in the heart; however, the relative importance of active and passive loading in regulating adult cardiocyte growth remains unresolved. To address this issue at the cellular level, adult feline cardiocytes were cultured either on Silastic membranes or plastic surfaces. Cardiocyte-laden membranes were stretched 10% of their rest length to enhance passive loading, whereas heart cells cultured on plastic or Silastic were field stimulated at 1 Hz to mimic active loading. Turnover of contractile proteins and structural integrity of the contractile-cytoskeletal apparatus were monitored for periods ranging from 4 to 72 h. Active and passive loading elevated contractile protein synthesis nearly equally (approximately 50%) and promoted the attachment of remodeled myofibrils to vinculin-positive focal contacts and/or costameres during the first 24 h of loading. Thereafter, rates of contractile protein synthesis returned to control values in passively stretched heart cells but remained elevated in field-stimulated cultures. The fractional rate of growth was increased significantly (approximately 8%/day) in electrically paced cells, whereas in passively stretched cardiocytes the growth rate rose only modestly (approximately 2%/day). Changes in the rate of myocyte growth appeared more closely correlated with the development of focal contacts and myofibril remodeling than with changes in myofibrillar protein turnover per se. 2,3-Butanedione monoxime, nifedipine, and, to a lesser extent, ryanodine blocked field-stimulated contractile protein synthesis and myofibrillar remodeling but had no impact on protein turnover or myofibril reassembly in passively loaded cardiocytes. The results of these experiments imply that both active and passive loading stimulate contractile protein turnover and myofibril remodeling, but the generation of active tension accelerates

  4. Rictor/TORC2 regulates fat metabolism, feeding, growth, and life span in Caenorhabditis elegans

    PubMed Central

    Soukas, Alexander A.; Kane, Elizabeth A.; Carr, Christopher E.; Melo, Justine A.; Ruvkun, Gary

    2009-01-01

    Rictor is a component of the target of rapamycin complex 2 (TORC2). While TORC2 has been implicated in insulin and other growth factor signaling pathways, the key inputs and outputs of this kinase complex remain unknown. We identified mutations in the Caenorhabditis elegans homolog of rictor in a forward genetic screen for increased body fat. Despite high body fat, rictor mutants are developmentally delayed, small in body size, lay an attenuated brood, and are short-lived, indicating that Rictor plays a critical role in appropriately partitioning calories between long-term energy stores and vital organismal processes. Rictor is also necessary to maintain normal feeding on nutrient-rich food sources. In contrast to wild-type animals, which grow more rapidly on nutrient-rich bacterial strains, rictor mutants display even slower growth, a further reduced body size, decreased energy expenditure, and a dramatically extended life span, apparently through inappropriate, decreased consumption of nutrient-rich food. Rictor acts directly in the intestine to regulate fat mass and whole-animal growth. Further, the high-fat phenotype of rictor mutants is genetically dependent on akt-1, akt-2, and serum and glucocorticoid-induced kinase-1 (sgk-1). Alternatively, the life span, growth, and reproductive phenotypes of rictor mutants are mediated predominantly by sgk-1. These data indicate that Rictor/TORC2 is a nutrient-sensitive complex with outputs to AKT and SGK to modulate the assessment of food quality and signal to fat metabolism, growth, feeding behavior, reproduction, and life span. PMID:19240135

  5. NFAT1 Directly Regulates IL8 and MMP3 to Promote Melanoma Tumor Growth and Metastasis.

    PubMed

    Shoshan, Einav; Braeuer, Russell R; Kamiya, Takafumi; Mobley, Aaron K; Huang, Li; Vasquez, Mayra E; Velazquez-Torres, Guermarie; Chakravarti, Nitin; Ivan, Cristina; Prieto, Victor; Villares, Gabriel J; Bar-Eli, Menashe

    2016-06-01

    Nuclear factor of activated T cell (NFAT1, NFATC2) is a transcription factor that binds and positively regulates IL2 expression during T-cell activation. NFAT1 has important roles in both innate and adaptive immune responses, but its involvement in cancer is not completely understood. We previously demonstrated that NFAT1 contributes to melanoma growth and metastasis by regulating the autotaxin gene (Enpp2). Here, we report a strong correlation between NFAT1 expression and metastatic potential in melanoma cell lines and tumor specimens. To elucidate the mechanisms underlying NFAT1 overexpression during melanoma progression, we conducted a microarray on a highly metastatic melanoma cell line in which NFAT1 expression was stably silenced. We identified and validated two downstream targets of NFAT1, IL8, and MMP3. Accordingly, NFAT1 depletion in metastatic melanoma cell lines was associated with reduced IL8 and MMP3 expression, whereas NFAT1 overexpression in a weakly metastatic cell line induced expression of these targets. Restoration of NFAT1 expression recovered IL8 and MMP3 expression levels back to baseline, indicating that both are direct targets of NFAT1. Moreover, in vivo studies demonstrated that NFAT1 and MMP3 promoted melanoma tumor growth and lung metastasis. Collectively, our findings assign a new role for NFAT1 in melanoma progression, underscoring the multifaceted functions that immunomodulatory factors may acquire in an unpredictable tumor microenvironment. Cancer Res; 76(11); 3145-55. ©2016 AACR. PMID:27013197

  6. The murine stanniocalcin 2 gene is a negative regulator of postnatal growth.

    PubMed

    Chang, Andy C-M; Hook, Jeff; Lemckert, Frances A; McDonald, Michelle M; Nguyen, Mai-Anh T; Hardeman, Edna C; Little, David G; Gunning, Peter W; Reddel, Roger R

    2008-05-01

    Stanniocalcin (STC), a secreted glycoprotein, was first studied in fish as a classical hormone with a role in regulating serum calcium levels. There are two closely related proteins in mammals, STC1 and STC2, with functions that are currently unclear. Both proteins are expressed in numerous mammalian tissues rather than being secreted from a specific endocrine gland. No phenotype has been detected yet in Stc1-null mice, and to investigate whether Stc2 could have compensated for the loss of Stc1, we have now generated Stc2(-/-) and Stc1(-/-) Stc2(-/-) mice. Although Stc1 is expressed in the ovary and lactating mouse mammary glands, like the Stc1(-/-) mice, the Stc1(-/-) Stc2(-/-) mice had no detected decrease in fertility, fecundity, or weight gain up until weaning. Serum calcium and phosphate levels were normal in Stc1(-/-) Stc2(-/-) mice, indicating it is unlikely that the mammalian stanniocalcins have a major physiological role in mineral homeostasis. Mice with Stc2 deleted were 10-15% larger and grew at a faster rate than wild-type mice from 4 wk onward, and the Stc1(-/-) Stc2(-/-) mice had a similar growth phenotype. This effect was not mediated through the GH/IGF-I axis. The results are consistent with STC2 being a negative regulator of postnatal growth. PMID:18258678

  7. Acetylbritannilactone Modulates Vascular Endothelial Growth Factor Signaling and Regulates Angiogenesis in Endothelial Cells

    PubMed Central

    Zhao, Jingshan; Niu, Honglin; Li, Aiying; Nie, Lei

    2016-01-01

    The present study was conducted to determine the effects of 1-O-acetylbritannilactone (ABL), a compound extracted from Inula britannica L., on vascular endothelial growth factor (VEGF) signaling and angiogenesis in endothelial cells (ECs). We showed that ABL promotes VEGF-induced cell proliferation, growth, migration, and tube formation in cultured human ECs. Furthermore, the modulatory effect of ABL on VEGF-induced Akt, MAPK p42/44, and p38 phosphorylation, as well as on upstream VEGFR-2 phosphorylation, were associated with VEGF-dependent Matrigel angiogenesis in vivo. In addition, animals treated with ABL (26 mg/kg/day) recovered blood flow significantly earlier than control animals, suggesting that ABL affects ischemia-mediated angiogenesis and arteriogenesis in vivo. Finally, we demonstrated that ABL strongly reduced the levels of VEGFR-2 on the cell surface, enhanced VEGFR-2 endocytosis, which consistent with inhibited VE-cadherin, a negative regulator of VEGF signaling associated with VEGFR-2 complex formation, but did not alter VE-cadherin or VEGFR-2 expression in ECs. Our results suggest that ABL may serve as a novel therapeutic intervention for various cardiovascular diseases, including chronic ischemia, by regulating VEGF signaling and modulating angiogenesis. PMID:26863518

  8. Genetic Analysis of Growth-Regulator-Induced Parthenocarpy in Arabidopsis1

    PubMed Central

    Vivian-Smith, Adam; Koltunow, Anna M.

    1999-01-01

    In Arabidopsis, seedless silique development or parthenocarpy can be induced by the application of various plant growth regulators (PGRs) to unfertilized pistils. Ecotype-specific responses were observed in the Arabidopsis ecotypes Columbia and Landsberg relative to the type of PGR and level applied. The parthenocarpic response was greatest in ecotype Landsberg, and comparisons of fruit growth and morphology were studied primarily in this ecotype. Gibberellic acid application (10 μmol pistil−1) caused development similar to that in pollinated pistils, while benzyladenine (1 μmol pistil−1) and naphthylacetic acid (10 μmol pistil−1) treatment produced shorter siliques. Naphthylacetic acid primarily modified mesocarp cell expansion. Arabidopsis mutants were employed to examine potential dependencies on gibberellin biosynthesis (ga1-3, ga4-1, and ga5-1) and perception (spy-4 and gai) during parthenocarpic silique development. Emasculated spy-4 pistils were neither obviously parthenocarpic nor deficient in PGR perception. By contrast, emasculated gai mutants did not produce parthenocarpic siliques following gibberellic acid application, but silique development occurred following pollination or application of auxin and cytokinin. Pollinated gai siliques had decreased cell numbers and morphologically resembled auxin-induced parthenocarpic siliques. This shows that a number of independent and possibly redundant pathways can direct hormone-induced parthenocarpy, and that endogenous gibberellins play a role in regulating cell expansion and promoting cell division in carpels. PMID:10517835

  9. AMPK is a negative regulator of the Warburg Effect and suppresses tumor growth in vivo

    PubMed Central

    Faubert, Brandon; Boily, Gino; Izreig, Said; Griss, Takla; Samborska, Bozena; Dong, Zhifeng; Dupuy, Fanny; Chambers, Christopher; Fuerth, Benjamin J.; Viollet, Benoit; Mamer, Orval A.; Avizonis, Daina; DeBerardinis, Ralph J.; Siegel, Peter M.; Jones, Russell G.

    2012-01-01

    Summary AMPK is a metabolic sensor that helps maintain cellular energy homeostasis. Despite evidence linking AMPK with tumor suppressor functions, the role of AMPK in tumorigenesis and tumor metabolism is unknown. Here we show that AMPK negatively regulates aerobic glycolysis (the Warburg effect) in cancer cells, and suppresses tumor growth in vivo. Genetic ablation of the α1 catalytic subunit of AMPK accelerates Myc-induced lymphomagenesis. Inactivation of AMPKα in both transformed and non-transformed cells promotes a metabolic shift to aerobic glycolysis, increased allocation of glucose carbon into lipids, and biomass accumulation. These metabolic effects require normoxic stabilization of the hypoxia-inducible factor-1α (HIF-1α), as silencing HIF-1α reverses the shift to aerobic glycolysis and the biosynthetic and proliferative advantages conferred by reduced AMPKα signaling. Together our findings suggest that AMPK activity opposes tumor development, and its loss fosters tumor progression in part by regulating cellular metabolic pathways that support cell growth and proliferation. PMID:23274086

  10. Identification of microtubule growth deceleration and its regulation by conserved and novel proteins.

    PubMed

    Lacroix, Benjamin; Ryan, Joël; Dumont, Julien; Maddox, Paul S; Maddox, Amy S

    2016-05-01

    Microtubules (MTs) are cytoskeletal polymers that participate in diverse cellular functions, including cell division, intracellular trafficking, and templating of cilia and flagella. MTs undergo dynamic instability, alternating between growth and shortening via catastrophe and rescue events. The rates and frequencies of MT dynamic parameters appear to be characteristic for a given cell type. We recently reported that all MT dynamic parameters vary throughout differentiation of a smooth muscle cell type in intact Caenorhabditis elegans. Here we describe local differences in MT dynamics and a novel MT behavior: an abrupt change in growth rate (deceleration) of single MTs occurring in the cell periphery of these cells. MT deceleration occurs where there is a decrease in local soluble tubulin concentration at the cell periphery. This local regulation of tubulin concentration and MT deceleration are dependent on two novel homologues of human cylicin. These novel ORFs, which we name cylc-1 and -2, share sequence homology with stathmins and encode small, very basic proteins containing several KKD/E repeats. The TOG domain-containing protein ZYG-9(TOGp) is responsible for the faster polymerization rate within the cell body. Thus we have defined two contributors to the molecular regulation for this novel MT behavior. PMID:26985017

  11. Genetic variation in circadian regulation of nocturnal stomatal conductance enhances carbon assimilation and growth.

    PubMed

    Resco de Dios, Víctor; Loik, Michael E; Smith, Renee; Aspinwall, Michael J; Tissue, David T

    2016-01-01

    Circadian resonance, whereby a plant's endogenous rhythms are tuned to match environmental cues, has been repeatedly shown to be adaptive, although the underlying mechanisms remain elusive. Concomitantly, the adaptive value of nocturnal transpiration in C3 plants remains unknown because it occurs without carbon assimilation. These seemingly unrelated processes are interconnected because circadian regulation drives temporal patterns in nocturnal stomatal conductance, with maximum values occurring immediately before dawn for many species. We grew individuals of six Eucalyptus camaldulensis genotypes in naturally lit glasshouses and measured sunset, predawn and midday leaf gas exchange and whole-plant biomass production. We tested whether sunrise anticipation by the circadian clock and subsequent increases in genotype predawn stomatal conductance led to rapid stomatal opening upon illumination, ultimately affecting genotype differences in carbon assimilation and growth. We observed faster stomatal responses to light inputs at sunrise in genotypes with higher predawn stomatal conductance. Moreover, early morning and midday stomatal conductance and carbon assimilation, leaf area and total plant biomass were all positively correlated with predawn stomatal conductance across genotypes. Our results lead to the novel hypothesis that genotypic variation in the circadian-regulated capacity to anticipate sunrise could be an important factor underlying intraspecific variation in tree growth. PMID:26147129

  12. Endothelial Snail Regulates Capillary Branching Morphogenesis via Vascular Endothelial Growth Factor Receptor 3 Expression

    PubMed Central

    Park, Jeong Ae; Kim, Dong Young; Kim, Young-Myeong; Kwon, Young-Guen

    2015-01-01

    Vascular branching morphogenesis is activated and maintained by several signaling pathways. Among them, vascular endothelial growth factor receptor 2 (VEGFR2) signaling is largely presented in arteries, and VEGFR3 signaling is in veins and capillaries. Recent reports have documented that Snail, a well-known epithelial-to-mesenchymal transition protein, is expressed in endothelial cells, where it regulates sprouting angiogenesis and embryonic vascular development. Here, we identified Snail as a regulator of VEGFR3 expression during capillary branching morphogenesis. Snail was dramatically upregulated in sprouting vessels in the developing retinal vasculature, including the leading-edged vessels and vertical sprouting vessels for capillary extension toward the deep retina. Results from in vitro functional studies demonstrate that Snail expression colocalized with VEGFR3 and upregulated VEGFR3 mRNA by directly binding to the VEGFR3 promoter via cooperating with early growth response protein-1. Snail knockdown in postnatal mice attenuated the formation of the deep capillary plexus, not only by impairing vertical sprouting vessels but also by downregulating VEGFR3 expression. Collectively, these data suggest that the Snail-VEGFR3 axis controls capillary extension, especially in vessels expressing VEGFR2 at low levels. PMID:26147525

  13. Ral-Arf6 crosstalk regulates Ral dependent exocyst trafficking and anchorage independent growth signalling.

    PubMed

    Pawar, Archana; Meier, Jeremy A; Dasgupta, Anwesha; Diwanji, Neha; Deshpande, Neha; Saxena, Kritika; Buwa, Natasha; Inchanalkar, Siddhi; Schwartz, Martin Alexander; Balasubramanian, Nagaraj

    2016-09-01

    Integrin dependent regulation of growth factor signalling confers anchorage dependence that is deregulated in cancers. Downstream of integrins and oncogenic Ras the small GTPase Ral is a vital mediator of adhesion dependent trafficking and signalling. This study identifies a novel regulatory crosstalk between Ral and Arf6 that controls Ral function in cells. In re-adherent mouse fibroblasts (MEFs) integrin dependent activation of RalA drives Arf6 activation. Independent of adhesion constitutively active RalA and RalB could both however activate Arf6. This is further conserved in oncogenic H-Ras containing bladder cancer T24 cells, which express anchorage independent active Ral that supports Arf6 activation. Arf6 mediates active Ral-exocyst dependent delivery of raft microdomains to the plasma membrane that supports anchorage independent growth signalling. Accordingly in T24 cells the RalB-Arf6 crosstalk is seen to preferentially regulate anchorage independent Erk signalling. Active Ral we further find uses a Ral-RalBP1-ARNO-Arf6 pathway to mediate Arf6 activation. This study hence identifies Arf6, through this regulatory crosstalk, to be a key downstream mediator of Ral isoform function along adhesion dependent pathways in normal and cancer cells. PMID:27269287

  14. Stress Regulates Aquaporin-8 Permeability to Impact Cell Growth and Survival

    PubMed Central

    Medraño-Fernandez, Iria; Bestetti, Stefano; Bertolotti, Milena; Bienert, Gerd P.; Bottino, Cinzia; Laforenza, Umberto; Rubartelli, Anna

    2016-01-01

    Abstract Aquaporin-8 (AQP8) allows the bidirectional transport of water and hydrogen peroxide across biological membranes. Depending on its concentration, H2O2 exerts opposite roles, amplifying growth factor signaling in physiological conditions, but causing severe cell damage when in excess. Thus, H2O2 permeability is likely to be tightly controlled in living cells. Aims: In this study, we investigated whether and how the transport of H2O2 through plasma membrane AQP8 is regulated, particularly during cell stress. Results: We show that diverse cellular stress conditions, including heat, hypoxia, and ER stress, reversibly inhibit the permeability of AQP8 to H2O2 and water. Preventing the accumulation of intracellular reactive oxygen species (ROS) during stress counteracts AQP8 blockade. Once inhibition is established, AQP8-dependent transport can be rescued by reducing agents. Neither H2O2 nor water transport is impaired in stressed cells expressing a mutant AQP8, in which cysteine 53 had been replaced by serine. Cells expressing this mutant are more resistant to stress-, drug-, and radiation-induced growth arrest and death. Innovation and Conclusion: The control of AQP8-mediated H2O2 transport provides a novel mechanism to regulate cell signaling and survival during stress. Antioxid. Redox Signal. 24, 1031–1044. PMID:26972385

  15. Identification of microtubule growth deceleration and its regulation by conserved and novel proteins

    PubMed Central

    Lacroix, Benjamin; Ryan, Joël; Dumont, Julien; Maddox, Paul S.; Maddox, Amy S.

    2016-01-01

    Microtubules (MTs) are cytoskeletal polymers that participate in diverse cellular functions, including cell division, intracellular trafficking, and templating of cilia and flagella. MTs undergo dynamic instability, alternating between growth and shortening via catastrophe and rescue events. The rates and frequencies of MT dynamic parameters appear to be characteristic for a given cell type. We recently reported that all MT dynamic parameters vary throughout differentiation of a smooth muscle cell type in intact Caenorhabditis elegans. Here we describe local differences in MT dynamics and a novel MT behavior: an abrupt change in growth rate (deceleration) of single MTs occurring in the cell periphery of these cells. MT deceleration occurs where there is a decrease in local soluble tubulin concentration at the cell periphery. This local regulation of tubulin concentration and MT deceleration are dependent on two novel homologues of human cylicin. These novel ORFs, which we name cylc-1 and -2, share sequence homology with stathmins and encode small, very basic proteins containing several KKD/E repeats. The TOG domain–containing protein ZYG-9TOGp is responsible for the faster polymerization rate within the cell body. Thus we have defined two contributors to the molecular regulation for this novel MT behavior. PMID:26985017

  16. Characterization and regulation of insulin-like growth factor binding proteins in human hepatic stellate cells.

    PubMed

    Gentilini, A; Feliers, D; Pinzani, M; Woodruff, K; Abboud, S

    1998-02-01

    Cultured hepatic stellate cells (HSCs), the cell type primarily involved in the progression of liver fibrosis, secrete insulin-like growth factor-I (IGF-I) and IGF binding protein (IGFBP) activity. IGF-I exerts a mitogenic effect on HSCs, thus potentially contributing to the fibrogenic process in an autocrine fashion. However, IGF-I action is modulated by the presence of specific IGFBPs that may inhibit and/or enhance its biologic effects. Therefore, we examined IGFBP-1 through IGFBP-6 mRNA and protein expression in HSCs isolated from human liver and activated in culture. Regulation of IGFBPs in response to IGF-I and other polypeptide growth factors involved in the hepatic fibrogenic process was also assessed. RNase protection assays and ligand blot analysis demonstrated that HSCs express IGFBP-2 through IGFBP-6 mRNAs and release detectable levels of IGFBP-2 through IGFBP-5. Because IGF-I, platelet-derived growth factor-BB (PDGF-BB), and transforming growth factor-beta (TGF-beta) stimulate HSC proliferation and/or matrix production, we tested their effect on IGFBPs released by HSCs. IGF-I induced IGFBP-3 and IGFBP-5 proteins in a time-dependent manner without an increase in the corresponding mRNAs. IGFBP-4 protein levels decreased in response to IGF-I. TGF-beta stimulated IGFBP-3 mRNA and protein but decreased IGFBP-5 mRNA and protein. In contrast, PDGF-BB failed to regulate IGFBPs compared with controls. Recombinant human IGFBP-3 (rhIGFBP-3) was then tested for its effect on IGF-I-induced mitogenesis in HSCs. rhIGFBP-3 inhibited IGF-I-stimulated DNA synthesis in a dose-dependent manner, with a peak effect observed at 25 nM IGFBP-3. Because TGF-beta is highly expressed in cirrhotic liver tissue, we determined whether IGFBP-3 mRNA expression is increased in liver biopsies obtained from patients with an active fibroproliferative response due to viral-induced chronic active hepatitis. In the majority of these samples, IGFBP-3 mRNA was increased compared with normal

  17. Differential Regulation of Vascular Endothelial Growth Factors by Promoter-targeted shRNAs.

    PubMed

    Laham-Karam, Nihay; Lalli, Marianne; Leinonen, Nastasia; Ylä-Herttuala, Seppo

    2015-01-01

    Vascular endothelial growth factors (VEGFs) and their receptors (VEGF-R) are central regulators of vasculogenesis, angiogenesis, and lymphangiogenesis. They contribute to many vascular-related pathologies, and hence VEGF-targeted therapies have been widely sought after. In this study, the authors investigated the ability of promoter-targeted small hairpin RNAs (shRNAs) to regulate VEGF-A, VEGF-C and VEGF-R1 in different cell lines. The authors identified shRNAs that can upregulate hVEGF-C at both the mRNA and protein levels, and differentially regulate hVEGF-A depending on the cell type. Likewise, the authors identified shRNA that downregulated VEGF-R1 gene expression. Hence, promoter-targeted shRNAs can affect endogenous gene expression not only bimodally, but also differentially in a cell-type specific manner. Importantly, all three genes tested were regulated by at least one shRNA, supporting the idea that nuclear RNA interference is a widespread phenomenon. The level of regulation across the panel of shRNAs varied maximally from a 2.2-fold increase to a 4-fold decrease. This level of change should be useful in fine-tuning and modulating target gene expression, which for potent molecules, such as VEGF-A and VEGF-C, can be very beneficial. These promoter-targeted shRNAs may facilitate the design and development of targeted, context-dependent strategies for both pro- and antiangiogenic therapies for the treatment of vascular-related pathologies. PMID:25988242

  18. Differential Regulation of Vascular Endothelial Growth Factors by Promoter-targeted shRNAs

    PubMed Central

    Laham-Karam, Nihay; Lalli, Marianne; Leinonen, Nastasia; Ylä-Herttuala, Seppo

    2015-01-01

    Vascular endothelial growth factors (VEGFs) and their receptors (VEGF-R) are central regulators of vasculogenesis, angiogenesis, and lymphangiogenesis. They contribute to many vascular-related pathologies, and hence VEGF-targeted therapies have been widely sought after. In this study, the authors investigated the ability of promoter-targeted small hairpin RNAs (shRNAs) to regulate VEGF-A, VEGF-C and VEGF-R1 in different cell lines. The authors identified shRNAs that can upregulate hVEGF-C at both the mRNA and protein levels, and differentially regulate hVEGF-A depending on the cell type. Likewise, the authors identified shRNA that downregulated VEGF-R1 gene expression. Hence, promoter-targeted shRNAs can affect endogenous gene expression not only bimodally, but also differentially in a cell-type specific manner. Importantly, all three genes tested were regulated by at least one shRNA, supporting the idea that nuclear RNA interference is a widespread phenomenon. The level of regulation across the panel of shRNAs varied maximally from a 2.2-fold increase to a 4-fold decrease. This level of change should be useful in fine-tuning and modulating target gene expression, which for potent molecules, such as VEGF-A and VEGF-C, can be very beneficial. These promoter-targeted shRNAs may facilitate the design and development of targeted, context-dependent strategies for both pro- and antiangiogenic therapies for the treatment of vascular-related pathologies. PMID:25988242

  19. MicroRNA miR-8 regulates multiple growth factor hormones produced from Drosophila fat cells.

    PubMed

    Lee, G J; Jun, J W; Hyun, S

    2015-06-01

    Metabolic organs such as the liver and adipose tissue produce several peptide hormones that influence metabolic homeostasis. Fat bodies, the Drosophila counterpart of liver and adipose tissues, have been thought to analogously secrete several hormones that affect organismal physiology, but their identity and regulation remain poorly understood. Previous studies have indicated that microRNA miR-8, functions in the fat body to non-autonomously regulate organismal growth, suggesting that fat body-derived humoral factors are regulated by miR-8. Here, we found that several putative peptide hormones known to have mitogenic effects are regulated by miR-8 in the fat body. Most members of the imaginal disc growth factors and two members of the adenosine deaminase-related growth factors are up-regulated in the absence of miR-8. Drosophila insulin-like peptide 6 (Dilp6) and imaginal morphogenesis protein-late 2 (Imp-L2), a binding partner of Dilp, are also up-regulated in the fat body of miR-8 null mutant larvae. The fat body-specific reintroduction of miR-8 into the miR-8 null mutants revealed six peptides that showed fat-body organ-autonomous regulation by miR-8. Amongst them, only Imp-L2 was found to be regulated by U-shaped, the miR-8 target for body growth. However, a rescue experiment by knockdown of Imp-L2 indicated that Imp-L2 alone does not account for miR-8's control over the insect's growth. Our findings suggest that multiple peptide hormones regulated by miR-8 in the fat body may collectively contribute to Drosophila growth. PMID:25492518

  20. PTHrP regulates the modeling of cortical bone surfaces at fibrous insertion sites during growth.

    PubMed

    Wang, Meina; VanHouten, Joshua N; Nasiri, Ali R; Johnson, Randy L; Broadus, Arthur E

    2013-03-01

    The sites that receive ligament and tendon insertions (entheses) on the cortical surfaces of long bones are poorly understood, particularly regarding modeling and regulation. Entheses are classified as either fibrocartilaginous or fibrous based on their structures. Fibrous entheses typically insert into the metaphysis or diaphysis of a long bone, bear a periosteal component, and are modeled during long-bone growth. This modeling forms a root system by which the insertions attach to the cortical surface. In the case of the medial collateral ligament, modeling drives actual migration of the ligament along the cortical surface in order to accommodate linear growth, whereas in other sites modeling may excavate a deep cortical root system (eg, the teres major insertion) or a shallow root system with a large footprint (eg, the latissimus dorsi insertion). We report here that conditionally deleting parathyroid hormone-related protein (PTHrP) in fibrous entheses via Scleraxis-Cre targeting causes modeling to fail in these three iterations of osteoclast-driven enthesis excavation or migration. These iterations appear to represent formes frustes of a common modeling strategy, presumably differing from each other as a consequence of differences in biomechanical control. In sites in which PTHrP is not induced, either physiologically or because of conditional deletion, modeling does not take place and fibrocartilage is induced. These findings represent the initial genetic evidence that PTHrP regulates periosteal/intramembranous bone cell activity on cortical bone surfaces and indicate that PTHrP serves as a load-induced modeling tool in fibrous insertion sites during linear growth. PMID:23109045

  1. Human neural progenitors express functional lysophospholipid receptors that regulate cell growth and morphology

    PubMed Central

    Hurst, Jillian H; Mumaw, Jennifer; Machacek, David W; Sturkie, Carla; Callihan, Phillip; Stice, Steve L; Hooks, Shelley B

    2008-01-01

    Background Lysophospholipids regulate the morphology and growth of neurons, neural cell lines, and neural progenitors. A stable human neural progenitor cell line is not currently available in which to study the role of lysophospholipids in human neural development. We recently established a stable, adherent human embryonic stem cell-derived neuroepithelial (hES-NEP) cell line which recapitulates morphological and phenotypic features of neural progenitor cells isolated from fetal tissue. The goal of this study was to determine if hES-NEP cells express functional lysophospholipid receptors, and if activation of these receptors mediates cellular responses critical for neural development. Results Our results demonstrate that Lysophosphatidic Acid (LPA) and Sphingosine-1-phosphate (S1P) receptors are functionally expressed in hES-NEP cells and are coupled to multiple cellular signaling pathways. We have shown that transcript levels for S1P1 receptor increased significantly in the transition from embryonic stem cell to hES-NEP. hES-NEP cells express LPA and S1P receptors coupled to Gi/o G-proteins that inhibit adenylyl cyclase and to Gq-like phospholipase C activity. LPA and S1P also induce p44/42 ERK MAP kinase phosphorylation in these cells and stimulate cell proliferation via Gi/o coupled receptors in an Epidermal Growth Factor Receptor (EGFR)- and ERK-dependent pathway. In contrast, LPA and S1P stimulate transient cell rounding and aggregation that is independent of EGFR and ERK, but dependent on the Rho effector p160 ROCK. Conclusion Thus, lysophospholipids regulate neural progenitor growth and morphology through distinct mechanisms. These findings establish human ES cell-derived NEP cells as a model system for studying the role of lysophospholipids in neural progenitors. PMID:19077254

  2. TOR signaling regulates planarian stem cells and controls localized and organismal growth.

    PubMed

    Peiris, T Harshani; Weckerle, Frank; Ozamoto, Elyse; Ramirez, Daniel; Davidian, Devon; García-Ojeda, Marcos E; Oviedo, Néstor J

    2012-04-01

    Target of Rapamycin (TOR) controls an evolutionarily conserved signaling pathway that modulates cellular growth and division by sensing levels of nutrients, energy and stress. As such, TOR signaling is a crucial component of tissues and organs that translates systemic signals into cellular behavior. The ubiquitous nature of TOR signaling, together with the difficulty of analyzing tissue during cellular turnover and repair, have limited our understanding of how this kinase operates throughout the body. Here, we use the planarian model system to address TOR regulation at the organismal level. The planarian TOR homolog (Smed-TOR) is ubiquitously expressed, including stem cells (neoblasts) and differentiated tissues. Inhibition of TOR with RNA interference severely restricts cell proliferation, allowing the study of neoblasts with restricted proliferative capacity during regeneration and systemic cell turnover. Strikingly, TOR signaling is required for neoblast response to amputation and localized growth (blastema). However, in the absence of TOR signaling, regeneration takes place only within differentiated tissues. In addition, TOR is essential for maintaining the balance between cell division and cell death, and its dysfunction leads to tissue degeneration and lack of organismal growth in the presence of nutrients. Finally, TOR function is likely to be mediated through TOR Complex 1 as its disruption recapitulates signs of the TOR phenotype. Our data reveal novel roles for TOR signaling in controlling adult stem cells at a systemic level and suggest a new paradigm for studying TOR function during physiological turnover and regeneration. PMID:22427692

  3. CXCR2 signaling regulates KRAS(G12D)-induced autocrine growth of pancreatic cancer

    PubMed Central

    Purohit, Abhilasha; Varney, Michelle; Rachagani, Satyanarayana; Ouellette, Michel M.; Batra, Surinder K.; Singh, Rakesh K.

    2016-01-01

    Pharmacological inhibition of RAS, the master regulator of pancreatic ductal adenocarcinoma (PDAC), continues to be a challenge. Mutations in various isoforms of RAS gene, including KRAS are known to upregulate CXC chemokines; however, their precise role in KRAS-driven pancreatic cancer remains unclear. In this report, we reveal a previously unidentified tumor cell-autonomous role of KRAS(G12D)-induced CXCR2 signaling in mediating growth of neoplastic PDAC cells. Progressively increasing expression of mCXCR2 and its ligands was detected in the malignant ductal cells of Pdx1-cre;LSL-Kras(G12D) mice. Knocking-down CXCR2 in KRAS(G12D)-bearing human pancreatic duct-derived cells demonstrated a significant decrease in the in vitro and in vivo tumor cell proliferation. Furthermore, CXCR2 antagonists showed selective growth inhibition of KRAS(G12D)-bearing cells in vitro. Intriguingly, both genetic and pharmacological inhibition of CXCR2 signaling in KRAS(G12D)-bearing pancreatic ductal cells reduced the levels of KRAS protein, strongly implying the presence of a KRAS-CXCR2 feed-forward loop. Together, these data demonstrate the role of CXCR2 signaling in KRAS(G12D)-induced growth transformation and progression in PDAC. PMID:26771140

  4. Aptamer-functionalized superporous hydrogels for sequestration and release of growth factors regulated via molecular recognition.

    PubMed

    Battig, Mark R; Huang, Yike; Chen, Niancao; Wang, Yong

    2014-09-01

    While the discovery of highly potent biologics has led to the development of promising therapies for various human diseases, biologics can cause severe toxicity if delivered inappropriately. Thus, great efforts have been made to synthesize polymeric systems for safe and efficient delivery of biologics. However, the application of polymeric delivery systems is often limited by problems such as harsh reaction conditions, low drug sequestration efficiency, and difficult drug release regulation. This study was aimed at developing a superporous material system with a hydrogel and an aptamer to overcome these challenges. The results have shown that the superporous hydrogel is capable of instantaneously and fully sequestering a large amount of growth factors, owing to the presence of superporous architectures and aptamers. Moreover, the sequestering and loading procedure does not involve any harsh conditions. The release kinetics of growth factors can be molecularly modulated by either changing the binding affinity of the aptamer or by using a triggering effector. Therefore, this study presents a promising superporous material for the delivery of highly potent biologics such as growth factors for clinical applications. PMID:24954732

  5. Vascular Endothelial Growth Factor A Regulates the Secretion of Different Angiogenic Factors in Lung Cancer Cells.

    PubMed

    Frezzetti, Daniela; Gallo, Marianna; Roma, Cristin; D'Alessio, Amelia; Maiello, Monica R; Bevilacqua, Simona; Normanno, Nicola; De Luca, Antonella

    2016-07-01

    Vascular endothelial growth factor A (VEGFA) is one of the main mediators of angiogenesis in non-small cell lung cancer (NSCLC). Recently, it has been described an autocrine feed-forward loop in NSCLC cells in which tumor-derived VEGFA promoted the secretion of VEGFA itself, amplifying the proangiogenic signal. In order to investigate the role of VEGFA in lung cancer progression, we assessed the effects of recombinant VEGFA on proliferation, migration, and secretion of other angiogenic factors in A549, H1975, and HCC827 NSCLC cell lines. We found that VEGFA did not affect NSCLC cell proliferation and migration. On the other hand, we demonstrated that VEGFA not only produced a strong and persistent increase of VEGFA itself but also significantly induced the secretion of a variety of angiogenic factors, including follistatin (FST), hepatocyte growth factor (HGF), angiopoietin-2 (ANGPT2), granulocyte-colony stimulating factor (G-CSF), interleukin (IL)-8, leptin (LEP), platelet/endothelial cell adhesion molecule 1 (PECAM-1), and platelet-derived growth factor bb (PDGF-BB). PI3K/AKT, RAS/ERK, and STAT3 signalling pathways were found to mediate the effects of VEGFA in NSCLC cell lines. We also observed that VEGFA