Trophic interactions directing proper kidney development

Univ Of North Carolina Chapel Hill, Chapel Hill NC

Investigators

Linked publications, trials & patents

Abstract

Abstract Vascular and neuronal networks permeate tissues throughout the body, perfusing them with oxygen and nutrients and enabling crosstalk with the central nervous system. A tight association between nerves and vessels is vital for reciprocal communication that maintains homeostasis. During development and regeneration, nerves and vessels grow and expand together, and, in many cases, vessels guide nerves to their targets. Recent investigations have uncovered novel roles for nerves in modulating developmental processes and regeneration in several organs. An ever-expanding repertoire of additional nerve functions is continuously being uncovered. However, there is a significant gap in our understanding of the neuro-vascular interplay within the developing kidney and whether nerves play active roles in kidney development. Therefore, we set out to begin addressing these deficiencies. We found nerve fibers first innervate the kidney at E13.5 through a strict association with vascular smooth muscle cells (VSMCs) of the maturing arteries. This association expands the nerve network alongside the arterial tree throughout development. Disrupting the arterial pattern also disrupts the nerve network, highlighting a reliance on the vasculature for guidance. Sympathetic and sensory neurons both innervate the kidney and associate with developing and mature nephrons. Strikingly, genetic ablation of kidney innervation leads to a deficit in postnatal nephron numbers. Based on our novel findings, we hypothesize that VSMCs guide kidney innervation to direct proper nephron differentiation. To test this, we will leverage our expertise in imaging and transcriptomics to interrogate phenotypes, identify pathways of cellular crosstalk, and gain mechanistic insights. In our first Aim, we will genetically ablate VSMCs to parse apart the reliance of nerves on VSMCs for initial kidney innervation versus continued guidance to developmental targets. Kidney VSMCs will be isolated at embryonic and postnatal stages for single-cell (sc)RNA-seq to determine the signaling pathway(s) required for neuro-vascular associations. By employing Translating Ribosome Affinity Purification (TRAP) to isolate transcripts actively translated in kidney axons, we will identify neuronal receptors critical for VSMC-nerve crosstalk. In our second Aim, we will genetically ablate sympathetic and sensory neurons independently or in combination to determine which neurons modulate nephrogenesis. We will employ light-sheet and confocal imaging, along with quantitative metrics, to interrogate nephron differentiation in our models and track phenotypes across development. To garner mechanistic insights into cellular programs that are disrupted by the absence of innervation, we will perform scRNA-seq on denervated kidneys, comparing the results to our phenotypic analyses to help identify the pathways involved. Additionally, we will interrogate the axonal transcriptome to determine signaling factors mediating nerve-kidney crosstalk. These studies will generate novel resources and insights into how nerves rely on the vasculature for proper guidance enabling them to modulate nephrogenesis. Our findings will support and enhance regenerative efforts and tissue replacement strategies.