Responses of Regulator of G Protein Signaling Proteins and Circadian Clock Components to Sustained...

Regulators of G protein signaling (RGSs) are key modulators of β-cell function and stress adaptation. Similarly, circadian clock components are intricately implicated in the regulation of insulin secretion and β-cell physiology. However, their responses to sustained cellular stimulation under depolarizing conditions remain incompletely understood. MIN6 cells were subjected to prolonged potassium chloride (KCl) exposure to induce sustained membrane depolarization, mimicking conditions of chronic β-cell stimulation. The expression levels of RGSs and core clock genes were analyzed, and associated changes in cellular stress and differentiation markers were assessed.KCl treatment led to the upregulation of endoplasmic reticulum (ER) stress markers, including C/-EBP homologous protein (CHOP) and activating transcription factor 4 (ATF4), with no induction of oxidative stress. Expression of RGS2, RGS4, and RGS16 was elevated. RGS2 partially co-localized with eukaryotic initiation factor-2α (eIF2α), suggesting a role in translational control during stress. Furthermore, KCl-induced depolarization was associated with characteristic changes in β-cell differentiation markers and disallowed genes, indicative of a dedifferentiation-like state. Transcript levels of several circadian genes were altered, including significant downregulation of D-site binding protein (DBP) and upregulation of its repressor E4-binding Protein 4 (E4BP4). Notably, differentiated embryo-chondrocyte expressed gene-1 (DEC1), a clock gene known to be inducible by various external stimuli, was also upregulated, suggesting broader circadian disruption under depolarizing conditions.Sustained membrane depolarization induces ER stress and transcriptional remodeling in MIN6 β-cells, including the modulation of RGS proteins and key circadian regulators such as DBP, E4BP4, and DEC1. These alterations may contribute to functional impairment and a dedifferentiation-like state of β-cells under chronic stimulatory conditions.