Inhibition of HMGB1 reduced high glucose-induced BMSCs apoptosis via activation of AMPK and regulation of mitochondrial functions

Abstract

High mobility group box-1 (HMGB1) participates actively in oxidative stress damage, and the latter relates closely to diabetes and diabetic complications including osteoporosis, though the underlying mechanisms are elusive. This study aimed to investigate the effect of high glucose on bone marrow stromal cells (BMSCs) apoptosis and the role of HMGB1 in this process. BMSCs were isolated from 2-week-old Sprague-Dawley rats and cultured in medium containing normal glucose (NG), high glucose (HG), high glucose + glycyrrhizin (HMGB1 inhibitor, HG+GL), and high glucose + glycyrrhizin + dorsomorphin (AMPK inhibitor, HG+GL+Dm), respectively. Cell apoptosis, expression of HMGB1, AMPK, apoptotic markers, and mitochondrial functions were detected. By these approaches, we demonstrated that HG treatment significantly upregulated the expression of HMGB1 in BMSCs, which could be attenuated by GL treatment. Inhibiting HMGB1 by GL improved AMPK activation, decreased mitochondrial ROS levels, increased mitochondrial membrane potential, normalized mitochondrial fission/fusion balance, and consequently reduced apoptosis of BMSCs under HG condition. The addition of AMPK inhibitor dorsomorphin hampered this protective effect. Taken together, our data show that inhibition of HMGB1 can be an effective approach to alleviate HG-induced BMSCs apoptosis by activation of AMPK pathway and relieving mitochondrial dysfunction.

Keywords: AMP-activated protein kinase (AMPK); Apoptosis; High mobility group box 1 (HMGB1); Mitochondria; Reactive oxygen species.