1. Catalytic-independent function of PARP-1 is essential in regulating human islet-cell differentiation from stem cells
- Author
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Nidheesh Dadheech, Abhay Srivast, Rashmi G. Shah, Girish M. Shah, and Sarita Gupta
- Abstract
Poly (ADP) Ribose Polymerase-1 (PARP-1), a fundamental DNA repair enzyme is known to regulate β cell death, replication, and insulin secretion. PARP-1 knockout (KO) mice are resistant to diabetes while PARP-1 overactivation contributes to β cell death. Additionally, PARP-1 inhibition improves diabetes complications in patients with type-2 diabetes. Despite these beneficial effects, the use of PARP-1 modulating agents in diabetes treatment are largely neglected, primarily due to the poorly studied mechanistic action of PARP-1 catalytic function in human β cell development. In the present study, we evaluated PARP-1 regulatory action in human β cell differentiation using the human pancreatic stem cell line, PANC-1. We surveyed islet census and histology from PARP-1 wild-type versus KO mice pancreas in head-to-head comparison with PARP-1 regulatory action for in-vitro β cell differentiation following either PARP-1 depletion or its pharmacological inhibition in PANC-1-differentiated islet cells. shRNA mediated PARP-1 depleted (SiP), or control replete (U6) PANC-1 cells were differentiated into islet-like clusters using established protocols. We observed complete abrogation of new β cell formation with absolute PARP-1 depletion while its catalytic inactivation using the strong inhibitor, PJ34, promoted the endocrine β cell differentiation and maturation. Immunohistochemistry and proteomics for key endocrine differentiation factors in addition to β cell maturation markers highlighted potential regulatory and augmented β cell differentiation due to non-catalytic function of PARP-1 elicited p-38 MAPK phosphorylation and Neurogenin-3 (Ngn3) re-activation. In summary, the study reestablishes a novel ability of catalytic independent action of PARP-1 in regulating islet cell differentiation and potential avenues for pilot clinical testing of PARP-1 inhibitors for β cell replacement therapies for the treatment of diabetes.
- Published
- 2022