Beta cell primary cilia mediate somatostatin responsiveness via SSTR3

Area of Science:

• Endocrinology
• Cell Biology
• Metabolic Research

Background:

• Somatostatin regulates insulin secretion and beta cell function, impacting glucose homeostasis.
• The precise mechanism of delta-to-beta cell communication via somatostatin is not fully understood.
• Primary cilia on islet cells act as signaling hubs, enriched with G-protein coupled receptors (GPCRs).

Purpose of the Study:

• To investigate the role of the ciliary somatostatin receptor 3 (SSTR3) in mediating somatostatin's effects on insulin secretion.
• To elucidate the mechanism of somatostatin-regulated beta cell calcium flux and its dependence on SSTR3 and primary cilia.

Main Methods:

• Utilized a mouse model with beta cell-specific GCaMP6f calcium reporter for quantitative calcium flux analysis.
• Investigated the impact of somatostatin signaling on beta cell calcium flux under physiologic glucose stimulation.
• Employed SSTR isoform antagonists in comparative in vitro studies to determine SSTR3's specific role.

Main Results:

• Somatostatin signaling, mediated by ciliary SSTR3, suppresses insulin secretion in mouse islets.
• Somatostatin alters beta cell calcium flux in a manner dependent on SSTR3 expression and intact primary cilia.
• SSTR3 plays a key role in somatostatin's regulation of insulin secretion.

Conclusions:

• Ciliary SSTR3 mediates a distinct delta-to-beta cell regulatory pathway.
• This pathway involves somatostatin's paracrine modulation of insulin secretion.
• SSTR3 represents a potential therapeutic target for modulating glucose homeostasis.