Role of motor protein myosin VI in subcellular distribution of NHE3 in the renal proximal tubule

• Grant number: 21/14045-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2022
• End date: January 31, 2024
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Adriana Castello Costa Girardi
• Grantee: Marcos Vinícius Caetano
• Host Institution: Instituto do Coração Professor Euryclides de Jesus Zerbini (INCOR). Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
• Associated research grant: 16/22140-7 - Molecular bases of renal tubular function and dysfunction, AP.TEM

Abstract

The Na+ /H+ exchanger isoform 3 (NHE3) is responsible for a large part of the reabsorption of NaCl, NaHCO3, and, consequently, water, in the renal proximal tubule. As such, this transporter plays an essential role in volume homeostasis, acid-base balance, and blood pressure control. The modulation of NHE3 activity is mediated by a series of molecular mechanisms, including the redistribution of the transporter among the microdomains of the apical membrane of the proximal tubule. Although the physiological, pharmacological, and pathophysiological importance of the subcellular distribution of NHE3 is very well established in the literature, the mechanisms involved in the translocation of this transporter from the body to the base of the microvilli and vice versa remain unclear. Evidence obtained from in vivo stationary microperfusion experiments showed that the activity of myosin VI, the only identified myosin that moves towards the end ( - ) of an actin filament, is essential to mediate NHE3 inhibition in response to parathyroid hormone, activation of the cAMP/PKA pathway and the biased angiotensin II receptor agonist, TRV (unpublished data). This project aims to elucidate the molecular mechanisms involved in the redistribution of NHE3 along the apical membrane subcompartments of the renal proximal tubule under conditions of sodium reabsorption inhibition in this nephron segment. To this end, we will perform immunoprecipitation assays to test the hypothesis that NHE3 physically interacts with myosin VI in the renal proximal tubule. Additionally, Blue Native-PAGE assays will be carried out to assess whether the NHE3-myosin VI protein complex is modulated in response to TRV. The knowledge obtained in this project can enable and improve therapeutic and pharmacological strategies for diseases such as hypertension arterial.(AU)