RESUMO
Objective:To investigate the effect of autophagy related gene Atg101 on white adipocyte senescence.Methods:An Atg101 knockdown model of 3T3-L1 mature adipocytes was constructed to probe the effect of Atg101 on autophagy-related proteins LC3 and p62 protein. The RNA-seq database of human subcutaneous adipose tissue was constructed and analyzed, and the co-expressed gene set was predicted based on the pearson correlation coefficient( R2>0.4, P<0.05) between FPKM values of Atg101 and other gene, followed by KEGG and Reactome enrichment analysis. Young mouse(8 weeks old) and old mouse(18 months old) models were established, and the expression levels of Atg101 in inguinal white adipose tissue and epididymal white adipose tissue were detected by quantitative real-time PCR(RT-qPCR) and Western blot. Furthermore, the differences in white adipocyte senescence-associated secretory phenotype(SASP), cell cycle and mitochondrial homeostasis-related genes were detected by RNA-seq, Western blot, and RT-qPCR to analyze the effects of Atg101 silencing on adipocyte senescence. Results:The autophagy-related protein LC3-Ⅱ expression was significantly decreased and p62 protein was induced after Atg101 was knockdowned in 3T3-L1 adipocytes, suggesting impaired cell autophagy. KEGG enrichment analysis revealed that Atg101 co-expressed gene set was mainly enriched in autophagy and senescence-related pathways; Reactome enrichment analysis revealed that this gene set was associated with multiple cell cycle signaling pathways. RT-qPCR and Western blot confirmed that both mRNA and protein levels of Atg101 were down-regulated in inguinal white adipose tissue of aging mice, and protein levels in epididymal white adipose tissue were also significantly reduced. Finally, it was further confirmed that SASP-related genes were induced after Atg101 knockdown in white adipocytes, and cell cycle-specific gene expression was restricted and cytokine-dependent protein kinase inhibitors p16 and p21 expressions were significantly increased, while mitochondrial homeostasis regulatory genes were also suppressed.Conclusions:Knockdown of Atg101 may regulate white adipocyte senescence by inhibiting autophagic activity, presenting impaired mitochondrial homeostasis.
RESUMO
Generally, human adipocytes can be broadly divided into white and brown fat cells. White fat cellsare specialized to store chemical energy and brownadipocytes can produce heat under external stimulation. Recent studies have demonstrated that when mice are exposed to cold or receive β-adrenergic stimulation, some brown-fat-like cells may appear in the subcutaneous white adipose depot, and these cells are called "beige cells". Beige cells have the characteristics of both white and brown fat cels and can transfer to each other. Biologically brown fat in adult humans is similar to beige cels. This paper is to review the research progress on beige cells.