Abstract: Differentiation of pancreatic progenitor cells (PPCs) into insulin-producing cells offers a promising approach for regenerating β cells and treating diabetes. Autophagy, essential for pancreatic β-cell development, plays a regulatory role in cellular differentiation. This study aims to investigate the role of SIRT1 in the differentiation of human PPCs/islet-like cell clusters (ICCs) and the molecular mechanism by which SIRT1 regulates autophagy.
Our results showed that SIRT1 translocated from the nucleus in PPCs to the cytoplasm in ICCs, accompanied by increased SIRT1 mRNA levels during differentiation. Overexpression of SIRT1 or SIRT1 activator SRT1720 significantly enhanced the levels of pancreatic endocrine differentiation markers (NGN3, NKX2.2, NKX6.1), maturation markers (INSULIN, PDX-1, GLUCAGON), and insulin content in ICCs. Conversely, SIRT1 knockdown or inhibition with EX527 had no such effects, indicating SIRT1 promotes PPCs/ICCs differentiation. Additionally, SIRT1 overexpression in ICCs enhanced their in vivo functionality to ameliorate progressive hyperglycemia in diabetic mouse model.
Mechanistically, autophagy levels increased during differentiation, with SRT1720 elevating autophagy markers (LC3-II and p62) and phosphorylation levels of ULK1 and AMP-activated protein kinase (AMPK). Inhibition of AMPK signaling by Compound C abrogated the differentiation-promoting effects of SRT1720, reducing insulin levels, autophagosome-positive cells, and phosphorylation of autophagy-related proteins. Knockdown of autophagy-related gene ATG16L1 abolished the inhibitory effect of SRT1720 on NOTCH signaling, eliminating its differentiation-promoting effect.
These findings highlight SIRT1 as a key regulator of PPCs differentiation via autophagy-mediated degradation of NOTCH signaling. This study advances our understanding of the transcriptional regulation of pancreatic stem cell differentiation by SIRT1 and provides new insights into its potential application in β-cell regeneration for diabetes therapy.
Funding Source: This work was supported by Medical Scientific Research Foundation of Guangdong Province (A2024424), National Natural Science Foundation of China (82000739) and Guangdong Basic Research Fund (2019A1515110128).
