Specific DNA hypomethylation of the lncRNA PANDAR leads to senescence of APC in obesity and T2D

Obesity accelerates aging, reduces lifespan, and increases the risk of type 2 diabetes (T2D). Obesity, T2D, and aging are also driven by common molecular mechanisms, including the functional decline of adipocyte precursor cells (APC) and the accumulation of senescent cells in the adipose tissue. However, the mechanisms involved in these alterations remain unclear. LncRNAs regulate cell senescence and may contribute to these abnormalities in obesity and T2D. Through a transcriptomic approach in APC from individuals with obesity and T2D (O-T2D) and from nonobese subjects (non-O), we identified the lncRNA PANDAR (PANDAR) as the top-ranked differentially expressed lncRNA. Here, we characterized the senescence phenotype of APC from individuals with obesity and with different glucose tolerance statuses and addressed whether PANDAR promotes senescence of APC in obesity and T2D. APC from individuals with obesity, particularly in those who had T2D, revealed increases in multiple senescence markers compared to nonobese. Q-PCR determination of PANDAR levels confirmed the up-regulation of the lncRNA in O-APC, which reached a 2.4-fold increase in O-T2D compared to the non-O APC (p<0.001). Bisulfite sequencing and luciferase reporter assays also revealed that the CpG -1317 within PANDAR promoter is hypo-methylated in O-APCs, especially in O-T2D, and is detrimental to the modulation of PANDAR expression. Notably, silencing of PANDAR in O-T2D APC promotes exit from cell senescence, as also indicated by a 60% reduction in the percentage of SA-β-gal positive cells (p<0.05) compared to the non-silenced cells. Both the expression of PANDAR and the percentage of methylation at the CpG -1317 in O- and non-O APC correlate with the percentage of SA-β-gal-positive cells. Finally, Q-PCR assay in blood cells revealed that PANDAR is also up-regulated 2.4-fold (p<0.001) in individuals with obesity compared to nonobese and that its levels might be modulated, as indicated by 35% decreased expression (p<0.05) in subjects who underwent bariatric surgery. In conclusion, we have demonstrated that the modulation of PANDAR expression by specific hypomethylation of the CpG -1317 characterizes the APC in obesity and T2D and leads to senescence of these cells. Also, our data provide evidence that the targeting of PANDAR reverts the senescence phenotype in APC, potentially mitigating disease progression.