Chloride-permeable channels in white adipocytes: their role in adipogenesis and membrane potential

Abstract

Ion fluxes, regulated by membrane potential (Vm), are vital to white fat adipocyte (WFA) function and adipogenesis. These processes present a novel target to intervene in obesity. To explore this possibility we applied transcriptomics, immunohistochemistry, electrophysiology and adipogenesis assays alongside siRNA and pharmacological tools to identify the chloride-permeable channel(s) that determine Vm of WFA and to test whether those channels: specifically SWELL1 (Lrrc8 family), TTYH2/3 and EAAT1 regulate adipocyte differentiation and adipogenesis. RNA sequencing and qPCR indicated confirmed the existence of Lrrc8a, Lrrc8b, Lrrc8c, Lrrc8d, Ttyh2, Ttyh3, Slc1a1 and Ano1 transcripts across different primary fat depots of rats, mouse, as well as a subset within 3T3-L1 adipocytes. The corresponding protein products: SWELL1 (Lrrc8x), TTYH2/3 (Ttyh2/3) and, EAAT1 (Slc1a1) were found in both the plasma-membrane and cytoplasm of primary and differentiated 3T3-L1 adipocytes whereas TMEM16A protein was only in primary adipocytes and undifferentiated 3T3-L1 pre-adipocytes. Functional studies showed that although siRNA knockdown or pharmacological blockade of SWELL1, TTYH2/3, or EAAT1 proteins did not affect Vm or electrophysiological characteristics, SWELL1 and TTYH2/3 knockdown significantly suppressed adipocyte differentiation and adipogenesis. Together, these findings reveal a role for SWELL1, TTYH2/3, and EAAT1 in adipogenesis and highlight their potential as targets for therapeutic strategies in obesity management. Although the precise chloride permeability responsible for adipocyte Vm remains to be defined, this work advances our understanding of adipocyte biology.