The V-type H + -ATPase is targeted in antidiuretic hormone control of the Malpighian "renal" tubules

• Published in: Proceedings of the National Academy of Sciences - PNAS 2023-12, Vol.120 (51), p.e2308602120
• Main Authors: Sajadi, Farwa, Vergara-Martínez, María Fernanda, Paluzzi, Jean-Paul V
• Format: Article
• Language: English
• Subjects: Aedes aegypti; Animals; Antidiuretics; Aquatic insects; Biological Sciences; Blood; Calcitonin; Dispersion; Diuresis; Diuretics; Diuretics - metabolism; Female; H+-transporting ATPase; Hormones; Immunoreactivity; Insects; Malpighian tubules; Malpighian Tubules - metabolism; Membranes; Mosquitoes; Neuropeptides - metabolism; Serotonin; Signal transduction; Vacuolar Proton-Translocating ATPases - metabolism; Vasopressins - metabolism
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2308602120

Like other insects, secretion by mosquito Malpighian tubules (MTs) is driven by the V-type H -ATPase (VA) localized in the apical membrane of principal cells. In , the antidiuretic neurohormone CAPA inhibits secretion by MTs stimulated by select diuretic hormones; however, the cellular effectors of this inhibitory signaling cascade remain unclear. Herein, we demonstrate that the VA inhibitor bafilomycin selectively inhibits serotonin (5HT)- and calcitonin-related diuretic hormone (DH )-stimulated secretion. VA activity increases in DH -treated MTs, whereas CAPA abolishes this increase through a NOS/cGMP/PKG signaling pathway. A critical feature of VA activation involves the reversible association of the cytosolic (V ) and membrane (V ) complexes. Indeed, higher V protein abundance was found in membrane fractions of DH -treated MTs, whereas CAPA significantly decreased V abundance in membrane fractions while increasing it in cytosolic fractions. V immunolocalization was observed strictly in the apical membrane of DH -treated MTs, whereas immunoreactivity was dispersed following CAPA treatment. VA complexes colocalized apically in female MTs shortly after a blood meal consistent with the peak and postpeak phases of diuresis. Comparatively, V immunoreactivity in MTs was more dispersed and did not colocalize with the V complex in the apical membrane at 3 h post blood meal, representing a time point after the late phase of diuresis has concluded. Therefore, CAPA inhibition of MTs involves reducing VA activity and promotes complex dissociation hindering secretion. Collectively, these findings reveal a key target in hormone-mediated inhibition of MTs countering diuresis that provides a deeper understanding of this critical physiological process necessary for hydromineral balance.