Renin Cells Drive Kidney Neurovascular Development and Arterial Remodeling when Renin Activity is Deficient.

Renin cells synthesize and release the hormone-enzyme renin to regulate blood pressure and fluid-electrolyte homeostasis. Their function and identity depend on communication with surrounding cells and nerve fibers within complex kidney structure. Because renin cells are rare -0.01 % of kidney cells- conventional histological approaches cannot capture their interaction with nerve fibers and surrounding cells within the nephron and its vasculature. Using a novel ultrabright renin cell-specific tdTomato reporter mouse, high-resolution 3D imaging, and single-cell RNA-Seq, we mapped the interactions of renin cells with growing axons during normal kidney vascular development, in response to threats to homeostasis, and a severe arterial disease caused by a defective renin enzyme. During embryonic kidney development, stromal and renin cell progenitors assemble the arterioles, express axon attractants and neurotrophins that establish the precise innervation of renin cells and arterioles in a centrifugal pattern. Hypotension and sodium depletion led to an increase in the volume and number of renin cells along the arterioles. Renin enzymatic deficiency led to hypertrophy and endocrine transformation of renal arterioles, aberrant axon sprouting and sympathetic hyperinnervation suggesting a feed-forward mechanism whereby renin cells and axons co-induce each other, orchestrate neurovascular development and arteriolar remodeling when renin cells are over stimulated.