ALCAT1 Deficiency Attenuates Obesity Induced Cellular Senescence in P16‐3MR Transgenic Mice

Abstract

IntroductionWorldwide, obesity is one of the underlying determinant of chronic metabolic diseases, including cardiovascular diseases, neurodegenerative diseases, and type II diabetes. Recent research points to an increasingly clear connection between accumulation of senescence cells and pathogenesis of the aforementioned diseases. Interestingly, senescence cells appear to mediate the above diseases even in the young. Accordingly, eliminating senescence cells pharmacologically or by exercise intervention may attenuate many of the pathologies associated with obesity. Our lab identified a novel pathway that links development of chronic metabolic diseases with mitochondrial dysfunction. We discovered that deletion of an Acyl CoA Lysocardiolipin Acyltransferase 1 (ALCAT1) gene in mice renders them resistant to a number of metabolic diseases. Here, using a comprehensive approach, we investigated whether ALCAT1 causes diet induced obesity by promoting accumulation of senescence cells.MethodsIn this study, we established ALCAT1 knockout (KO) mice using a recently published transgenic mouse model. This transgenic model makes possible assessing senescence in live mice by means of bioluminescence imaging. Wild type (WT) and ALCAT1 knockout (KO) mice both containing a transgenic expression of the trimodality reporter (3MR) fusion protein driven by the p16 promoter (p16‐3MR) were used for the study. Mice were fed either control diet or high‐fat diet for 12 weeks. IVIS spectrum whole‐body imaging system was used to assess senescence in live mice. Protein expression, ELISA, histology, enzymatic assays, bioenergetics, and microscopy experiments were conducted following standard protocols.ResultsWT mice on high‐fat diet (WT‐HF) had significantly increased body weight and fasting blood glucose levels. In vivo imagining and western blots revealed that WT‐HF had increased bioluminescence and expression of ALCAT1 and P16. Senescence associated beta‐galactosidase (SA‐β‐gal) staining was detected in the fat biopsies of WT‐HF. Senescence associated secretory associated phenotype (SASP) factors such as IL‐6 and MCP‐1 were significantly increased in the tissue, primary cells, conditional medium, and blood plasma of WT‐HF. Moreover, oxidative stress, bioenergetics dysfunctions, reduced EdU incorporation and impaired lipid droplet accumulation, were found in preadipocytes isolated from WT‐HF.ConclusionsThe p16‐3MR mice revealed that ablation of ALCAT1 prevents the onset of high‐fat diet induced obesity through depletion of senescent cells in the adipose tissue. Together, our work provides vital molecular insights onto the mechanism by which ALCAT1 may promote cellular senescence. Because ALCAT1 is an enzyme, future work may establish small molecule inhibitors, which would offer great potential for translational applications.Support or Funding InformationLive Mouse Bioluminescence studies were conducted in the UT Health Core Optical Imaging Facility which is supported by UTHSCSA, NIH‐NCI P30 CA54174 CTRC and NIH‐NIA P01AG19316. This work was funded by NIH 2R01DK076685‐06A1), ADA 1‐14‐BS‐185, and support from a T32 training grant from Dr. Nicolas Musi through the Biology of Aging (T32 AG021890, supporting K.S.M starting May 2016 – April 2019).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.