Document Type
Article
Language
eng
Format of Original
7 p.
Publication Date
5-2013
Publisher
American Physiological Society
Source Publication
American Journal of Physiology: Renal Physiology
Source ISSN
1931-857X
Abstract
The rate of urine secretion by insect Malpighian tubules (MTs) is regulated by multiple diuretic and antidiuretic hormones, often working either synergistically or antagonistically. In the Drosophila melanogaster MT, only diuretic factors have been reported. Two such agents are the biogenic amine tyramine (TA) and the peptide drosokinin (DK), both of which act on the stellate cells of the tubule to increase transepithelial chloride conductance. In the current study, TA and DK signaling was quantified by microelectrode recording of the transepithelial potential in isolated Drosophila MTs. Treatment of tubules with cGMP caused a significant reduction in the depolarizing responses to both TA and DK, while cAMP had no effect on these responses. To determine whether a specific cGMP-dependent protein kinase (PKG) was mediating this inhibition, PKG expression was knocked down by RNAi in either the principal cells or the stellate cells. Knockdown of Pkg21D in the stellate cells eliminated the modulation of TA and DK signaling. Knockdown of Pkg21D with a second RNAi construct also reduced the modulation of TA signaling. In contrast, knockdown of the expression of foraging or CG4839, which encodes a known and a putative PKG, respectively, had no effect. These data indicate that cGMP, acting through the Pkg21D gene product in the stellate cells, can inhibit signaling by the diuretic agents TA and DK. This represents a novel function for cGMP and PKG in the Drosophila MT and suggests the existence of an antidiuretic hormone in Drosophila.
Recommended Citation
Ruka, Kristen A.; Miller, Anna P.; and Blumenthal, Edward M., "Inhibition of Diuretic Stimulation of an Insect Secretory Epithelium by a cGMP-Dependent Protein Kinase" (2013). Biological Sciences Faculty Research and Publications. 257.
https://epublications.marquette.edu/bio_fac/257
Comments
Accepted version. American Journal of Physiology: Renal Physiology, Vol. 304, No. 9 (May 2013): 1210-1216. DOI. © 2013 American Physiological Society. Used with permission.