Cholesterol-Dependent Dynamics of the Serotonin_1A Receptor Utilizing Single Particle Tracking: Analysis of Diffusion Modes

Abstract

G protein-coupled receptors (GPCRs) are signaling hubs in cell membranes that regulate a wide range of physiological processes and are popular drug targets. Serotonin1A receptors are important members of the GPCR family and are implicated in neuropsychiatric disorders. Cholesterol is a key constituent of higher eukaryotic membranes and is believed to contribute to the segregated distribution of membrane constituents into domains. To explore the role of cholesterol in lateral dynamics of GPCRs, we utilized single particle tracking (SPT) to monitor diffusion of serotonin1A receptors under acute and chronic cholesterol-depleted conditions. Our results show that the short-term diffusion coefficient of the receptor decreases upon cholesterol depletion, irrespective of the method of cholesterol depletion. Analysis of SPT trajectories revealed that relative populations of receptors undergoing various modes of diffusion change upon cholesterol depletion. Notably, in cholesterol-depleted cells, we observed an increase in the confined population of the receptor accompanied by a reduction in diffusion coefficient for chronic cholesterol depletion. These results are supported by our recent work and present observations that show polymerization of G-actin in response to chronic cholesterol depletion. Taken together, our results bring out the interdependence of cholesterol and actin cytoskeleton in regulating diffusion of GPCRs in membranes.

Molecular mapping and functional validation of GLP-1R cholesterol binding sites in pancreatic beta cells

“…Cholesterol, in particular, has been identified as an allosteric modulator for certain GPCRs, due to its direct binding to (21, 22) and modulation of GPCR activation, trafficking, and signalling patterns (23, 24). A previous study from our laboratory established that the GLP-1R function in pancreatic beta cells is also modulated by cholesterol.…”

Interplay of Cholesterol and Actin in Neurotransmitter GPCR Signaling: Insights from Chronic Cholesterol Depletion Using Statin

“…Consequently, receptor dynamics (lateral diffusion) in membranes determines overall efficacy of the signal transduction process. − In this overall context, measurement of live cell membrane dynamics, with the objective of correlating it with receptor signaling, assumes relevance. Interestingly, the actin cytoskeleton has emerged as a modulator of mobility (lateral diffusion) of membrane proteins in the plasma membrane − and dynamic reorganization of the actin cytoskeleton has been shown to modulate GPCR signaling. , …”