G Protein-Coupled Receptor 35 Suppresses Oxidative Stress Responsive Kinase 1 in Diabetic Wound Healing

G protein-coupled receptor 35 (GPR35) is a poorly characterized receptor with unclear intracellular mechanisms in endothelial cells (ECs). Oxidative stress responsive kinase 1 (OXSR1) is a serine/threonine protein kinase that modulates cell morphology and has recently been found to promote angiogenesis. We hypothesized that GPR35 inhibition promotes EC angiogenesis via augmenting OXSR1 activity and accelerating wound healing in diabetes. Here, we show that active GPR35 contributed to the impaired migration and tube formation of human dermal microvascular ECs from patients with type 2 diabetes (T2D) or ECs exposed to high glucose. Proximity labeling and coimmunoprecipitation identified OXSR1 as an interacting partner of GPR35 in ECs. GPR35 suppressed OXSR1 from translocating to nuclei to activate SMAD1/5, thereby inhibiting the transcription of angiogenic factors. Furthermore, enhanced wound angiogenic response and accelerated wound closures were observed in induced T2D mice with topical application of GPR35 siRNA, or in T2D models of transgenic mice with either global or endothelial-selective GPR35 deletion. Our data suggest that GPR35 suppresses OXSR1-dependent angiogenic activity in ECs, contributing to poor angiogenesis and delayed wound healing in T2D animals. This study provides both in vitro and in vivo evidence for GPR35 as a potential therapeutic target in tissue repair in patients with diabetes.

Endothelial cell dysfunction is a crucial feature of diabetic wound healing. The underlying molecular mechanisms are poorly understood. We investigated how G protein-coupled receptor 35 (GPR35) inhibition accelerates diabetic wound healing. We found that GPR35 modulated endothelial cell behavior in vitro and identified oxidative stress responsive 1 as its target. Inhibiting GPR35 rescued the healing process in animals with hyperglycemia. This study uncovers novel molecular mechanisms underlying the benefit of GPR35 inhibition on endothelial cell angiogenesis and provides proof-of-concept evidence for therapeutic strategies targeting GPR35 in the endothelium as a potential therapy for diabetic wound care.