Zebrafish mesonephric renin cells are functionally conserved and comprise two distinct morphological populations

Area of Science:

• Comparative physiology
• Renal biology
• Endocrinology

Background:

• The renin-angiotensin system (RAS) is crucial for blood pressure and fluid homeostasis.
• Zebrafish offer a unique vertebrate model for studying renal development and function.
• Understanding teleost RAS regulation provides insights into vertebrate kidney evolution.

Purpose of the Study:

• To investigate the phenotype and regulation of renin-expressing cells in zebrafish kidneys.
• To assess the functional conservation of the renin-angiotensin system in zebrafish.
• To determine if renin transcription serves as a marker for renal injury and repair in zebrafish.

Main Methods:

• Utilized transgenic zebrafish with fluorescent reporters for renin (ren), acta2, and pdgfrb.
• Analyzed renin-expressing cell morphology and secretory ultrastructure using electron microscopy.
• Examined whole kidney ren transcription in response to altered salinity, RAS inhibition, and renal injury.

Main Results:

• Mesonephric renin cells were located in preglomerular arteries and afferent arterioles, forming granular clusters.
• Renin cells in efferent arterioles were thin-bodied and lacked secretory granules.
• Whole kidney ren transcription responded to physiological challenges, indicating a functional RAS and its role in renal injury and repair.

Conclusions:

• Zebrafish possess a functional renin-angiotensin system with conserved regulatory mechanisms across vertebrates.
• Renin-expressing cells exhibit distinct morphologies, suggesting specialized functions.
• Renin transcription is a reliable marker for monitoring renal injury and repair in zebrafish kidneys.