Affiliation:
1. Department of Biology, York University, Toronto, ON M3J 1P3, Canada
2. Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México City, 04510, México
Abstract
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
Aedes aegypti
, 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
31
)-stimulated secretion. VA activity increases in DH
31
-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
1
) and membrane (V
o
) complexes. Indeed, higher V
1
protein abundance was found in membrane fractions of DH
31
-treated MTs, whereas CAPA significantly decreased V
1
abundance in membrane fractions while increasing it in cytosolic fractions. V
1
immunolocalization was observed strictly in the apical membrane of DH
31
-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
1
immunoreactivity in MTs was more dispersed and did not colocalize with the V
o
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.
Funder
Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada
MDECEC | Ontario Ministry of Research and Innovation
Publisher
Proceedings of the National Academy of Sciences
Cited by
1 articles.
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