INVESTIGATING MOLECULAR PATHWAYS OF CELLULAR SENESCENCE IN PREADIPOCYTES

Abstract

Obesity promotes premature aging and dysfunction of white adipose tissue (WAT) through the accumulation of cellular senescence. Senescent cells burden in WAT has been linked to inflammation, insulin-resistance, and Type 2 Diabetes. There is limited knowledge about molecular mechanisms that sustain inflammation in obese states. Here, we described a robust in vitro system to trigger senescence in mouse 3T3-L1 preadipocytes and by employing transcriptomics analyses; we identified altered molecular pathways and potential key regulators of senescence and inflammation. We focused our investigations on 1) Examining the function of upregulated key transcription factors in regulating senescence-associated phenotypes and 2) Evaluating the loss of function of downregulated nuclear proteins in cellular senescence. In the first project, we studied mechanisms of STATs/interferon signaling in regulating senescence and inflammation in mouse preadipocytes. To test the relevance of STAT1/3 signaling to preadipocyte senescence, we used CRISPR/Cas9 technology to delete STAT1/3 discovered that STAT1 promoted growth arrest, which was cooperated with cGAS-STING that drove the expression of interferon signaling related genes. In contrast, we discovered that STAT3 was a negative regulator of STAT1/cGAS-STING signaling; it suppressed senescence and inflammation. The second arm of our investigations was focused on defining the function of KIF4A in regulating senescence-associated phenotype. By employing CRISPR/Cas9 technology to delete KIF4A, which resulted in senescence-like phenotype, growth arrest, and downregulation of interferon signaling related genes. Transcriptomics analysis for KIF4A deletion revealed activation of TRIM24, which downregulated STAT1 thereby inhibiting the expression of interferon signaling related genes. Interestingly, STAT3 was activated following KIF4A deletion as well. These data provide insights into how STAT1/STAT3 signaling coordinates senescence and inflammation in preadipocytes. Eventually, this study will enhance our understanding of key molecular mechanisms of senescence and inflammation, which will help in the development of effective therapeutic strategies for obese people living with diabetes.

Date of Award	2021
Original language	American English
Awarding Institution	HBKU College of Health & Life Sciences