Chan, Yee Kwan; Sung, Hye Kyoung; Jahng, James Won Suk; Kim, Grace Ha Eun; Han, Meng; Sweeney, Gary
Lipocalin-2 (Lcn2; also known as neutrophil gelatinase associated lipocalin, NGAL) levels are increased in obesity and diabetes and associate with insulin resistance. Correlations exist between Lcn2 levels and various forms or stages of heart failure. Insulin resistance and autophagy both play well-established roles in cardiomyopathy. However, little is known about the impact of Lcn2 on insulin signaling in cardiomyocytes. In this study, we treated H9c2 cells with recombinant Lcn2 for 1 h followed by dose- and time-dependent insulin treatment and found that Lcn2 attenuated insulin signaling assessed via phosphorylation of Akt and p70S6K. We used multiple assays to demonstrate that Lcn2 reduced autophagic flux. First, Lcn2 reduced pULK1 S555, increased pULK1 S757 and reduced LC3-II levels determined by Western blotting. We validated the use of DQ-BSA to assess autolysosomal protein degradation and this together with MagicRed cathepsin B assay indicated that Lcn2 reduced lysosomal degradative activity. Furthermore, we generated H9c2 cells stably expressing tandem fluorescent RFP/GFP-LC3 and this approach verified that Lcn2 decreased autophagic flux. We also created an autophagy-deficient H9c2 cell model by overexpressing a dominant-negative Atg5 mutant and found that reduced autophagy levels also induced insulin resistance. Adding rapamycin after Lcn2 could stimulate autophagy and recover insulin sensitivity. In conclusion, our study indicated that acute Lcn2 treatment caused insulin resistance and use of gain and loss of function approaches elucidated a causative link between autophagy inhibition and regulation of insulin sensitivity by Lcn2. PMID:27090568
Ma, Guixin; Luo, Weiwei; Lu, Jinjian; Ma, Dik-Lung; Leung, Chung-Hang; Wang, Yitao; Chen, Xiuping
Cucurbitacin E (CuE) is a triterpenoid with potent anticancer activities while the underlying mechanisms remain elusive. In the present study, the anticancer effects of CuE on 95D lung cancer cells were investigated. CuE decreased cell viability, inhibited colony formation, and increased reactive oxygen species (ROS) in a concentration-dependent manner, which were reversed by N-acetyl-l-cysteine (NAC). CuE induced apoptosis as determined by JC-1 staining, expression of Bcl-2 family proteins, cleavage of caspases, and TUNEL staining. NAC and Ac-DEVD-CHO partially reversed CuE-induced cleavage of caspase-3, caspase-7, and PARP. Furthermore, CuE caused accumulation of autophagic vacuoles and concentration- and time-dependent expression of LC3II protein. Autophagy inhibitors chloroquine and bafilomycin A1 enhanced CuE-induced LC3II expression and cell death. CuE-triggered protein expression of p-AKT, p-mTOR, Beclin-1, and p-ULK1 was partially reversed by NAC pretreatment. In addition, CuE treatment damaged F-actin without affecting β-tubulin as confirmed by immunofluorescence. In conclusion, CuE induced ROS-dependent apoptosis through Bcl-2 family and caspases in 95D lung cancer cells. Furthermore, CuE induced protective autophagy mediated by ROS through AKT/mTOR pathway. This study provides novel roles of ROS in the anticancer effect of CuE. PMID:27106530
Lindeberg, M; Collmer, A
Many extracellular proteins produced by Erwinia chrysanthemi require the out gene products for transport across the outer membrane. In a previous report (S. Y. He, M. Lindeberg, A. K. Chatterjee, and A. Collmer, Proc. Natl. Acad. Sci. USA 88:1079-1083, 1991) cosmid pCPP2006, sufficient for secretion of Erwinia chrysanthemi extracellular proteins by Escherichia coli, was partially sequenced, revealing four out genes sharing high homology with pulH through pulK from Klebsiella oxytoca. The nucleotide sequence of eight additional out genes reveals homology with pulC through pulG, pulL, pulM, pulO, and other genes involved in secretion by various gram-negative bacteria. Although signal sequences and hydrophobic regions are generally conserved between Pul and Out proteins, four out genes contain unique inserts, a pulN homolog is not present, and outO appears to be transcribed separately from outC through outM. The sequenced region was subcloned, and an additional 7.6-kb region upstream was identified as being required for secretion in E. coli. out gene homologs were found on Erwinia carotovora cosmid clone pAKC651 but were not detected in E. coli. The outC-through-outM operon is weakly induced by polygalacturonic acid and strongly expressed in the early stationary phase. The out and pul genes are highly similar in sequence, hydropathic properties, and overall arrangement but differ in both transcriptional organization and the nature of their induction. Images PMID:1429461
Waagen, Elizabeth O.
V834 CAR = Nova Car 2012 = TCP J10502000-6406480 was discovered by John Seach, Chatsworth Island, NSW, Australia, at magnitude 10.2 on 3 images with digital SLR, 50 mm f/1.0 lens on 2012 February 26.543 UT. The discovery was confirmed by Arto Oksanen, Muurame, Finland, and Caisey Harlingten at V=10.4 from CCD images taken 2012 March 1.1552 UT with a 0.50-m telescope in San Pedro de Atacama, Chile. Coordinates (from Oksanen and Harlingten): RA 10 50 19.66 Dec. -64 06 46.7 (J2000.0). Red spectra by F. M. Walter, Stony Brook University, and M. Hernandez, Cerro Tololo Interamerican Observatory, taken Mar. 7.01 UT with the SMARTS 1.5-m telescope (+ RC spectrograph) indicate the object appears to be a classical Fe II nova near maximum. N. N. Samus, on behalf of the GCVS team, reports that the name V834 Car has been assigned to this nova. The object was listed on Central Bueau for Astronomical Telegrams Transient Objects Confirmation Page (TOCP) as TCP J10502000-6406480. The discovery was initially announced in AAVSO Special Notice #266 (Waagen); additional information was published in IAU CBET 3040 (Daniel W. E. Green, ed.) and IAU Circular 9251 (Green, ed.). Finder charts and over 3,200 visual and photometric observations of V834 Car are available from the AAVSO (http://www.aavso.org). AAVSO International Database observations show that from its discovery at magnitude 10.4 on 2012 Mar. 1-2 UT, the nova has declined to magnitude 12.2 as of 2012 Mar. 15-16 UT.