Locally produced nerve growth factor is a novel regulator of (juxta)glomerular and collecting duct functions in the kidney
Authors: Trogen Greta , Izuhara Audrey , Becerra Calderon Alejandra , Deepak Sachin , Gyarmati Georgina , Peti-Peterdi Janos 
Published: May 2024

The dense network of sympathetic efferent and sensory afferent nerves innervating the kidney is well recognized, however the elements and the functional importance of neurotrophin signaling in renal tissues are much less known. Peripherally innervated tissues are known to produce and release nerve growth factor (NGF) which belongs to the neurotrophin family of neuronal signaling proteins and is essential for the growth and survival of peripheral sensory and sympathetic nerves. This study aimed to characterize the expression and role of NGF in the kidney. We hypothesized that NGF is produced by multiple renal tubular and vascular cell types and helps to maintain hemodynamic and tubular transport functions. Local NGF expression was studied using histological sections of kidneys harvested from NGF-GFP reporter mice. To address the functional importance of NGF signaling, a new mouse model was generated by crossing Ren1d-Cre and NGF-floxed mice and Cre/lox-mediated knockout of NGF from cells of the renin lineage co-labeled with the multicolor reporter Confetti (Ren1d-Confetti-NGF KO). WT and NGF KO mice were placed in metabolic cages for urine collections and analysis, and systolic blood pressure (SBP) was measured with tail-cuff pletysmography. Intercalated cells of the collecting duct (CD) showed by far the highest NGF expression among all renal cell types based on the reporter signal in NGF-GFP mice, in addition to select cells in the renal interstitium including juxtaglomerular (JG) renin cells. Since both CD cells and JG cells are part of the renin lineage, the applied genetic strategy using Ren1d-Confetti-NGF KO mice was ideal, and showed diminished NGF expression compared to WT. Urine excretion rate and albuminuria were 3-fold increased in Ren1d-Confetti-NGF KO vs. WT mice, while there was no difference in SBP between WT and KO groups. Immunohistochemistry showed aberrant CD structure with multiple small, undifferentiated cells with apparently lost polarity and reduced AQP2 labeling in CD principal cells in Ren1d-Confetti-NGF KO mice compared to WT. In addition, the characteristic strong apical membrane AQP2 (in principal cells) and H+-ATPase (in intercalated cells) labeling in WT mice was diminished in Ren1d-Confetti-NGF KO mice. JG renin cell number per nephron was significantly reduced in Ren1d-Confetti-NGF KO (2.5±1.0) vs. WT mice (6.2±1.5, n=4 mice each). In summary, our results suggest high level of NGF expression in the adult kidney that plays important physiological functional roles in maintaining collecting duct water and electrolyte reabsorption and acid secretion, and intrarenal renin production. Deficient intrarenal NGF production may cause kidney disease, suggesting the importance of altered renal neurotrophin signaling in pathology development. DK064234, DK123564, DK135290. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.