Guanylin peptides: renal actions mediated by cyclic GMP

Area of Science:

• Endocrinology
• Molecular Biology
• Physiology

Background:

• The guanylin peptide family comprises three subclasses: ST, guanylin/uroguanylin, and lymphoguanylin, distinguished by disulfide bonds.
• These peptides activate cell-surface guanylate cyclase (GC) receptors, including intestinal GC-C and kidney OK-GC.
• Guanylin peptides play roles in regulating cGMP production, fluid secretion, and electrolyte balance.

Purpose of the Study:

• To elucidate the physiological roles of guanylin peptides in regulating cGMP and their impact on kidney and intestinal functions.
• To understand the mechanism by which guanylin peptides influence sodium homeostasis and fluid balance.
• To explore the potential endocrine axis between the digestive system and kidney involving uroguanylin and guanylin.

Main Methods:

• Analysis of guanylin peptide subclasses and their disulfide bond configurations.
• Identification and characterization of receptor guanylate cyclases (GC-C, OK-GC).
• In vivo and ex vivo studies on the effects of guanylin peptides on renal and intestinal cells.

Main Results:

• Guanylin peptides stimulate cGMP production, leading to diuresis, natriuresis, and kaliuresis in renal cells.
• Activation of intestinal GC-C receptors by guanylin peptides enhances Cl(-) and HCO(3)(-) secretion, increasing fluid and electrolyte secretion.
• Bacterial ST peptides mimic endogenous guanylins, causing diarrhea by activating intestinal GC-C.
• Uroguanylin and guanylin may form an endocrine axis influencing Na(+) homeostasis.
• Guanylin peptides may also act in intrarenal signaling pathways.

Conclusions:

• Guanylin peptides are key regulators of cGMP, influencing both renal and intestinal functions.
• These peptides are involved in a complex system for excreting excess NaCl, maintaining sodium balance.
• Uroguanylin is proposed as a potential