Al-Dailami Areej N, Lange Angela B, Orchard Ian
Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada, L5L 1C6.
J Exp Biol. 2024 Dec 15;227(24). doi: 10.1242/jeb.249357. Epub 2024 Dec 10.
In the hemipteran Rhodnius prolixus, successful post-prandial diuresis is accomplished through the synergistic actions of the peptidergic diuretic hormone RhoprCRF/DH and the biogenic amine 5-hydroxytryptamine (5-HT), and by an antidiuretic hormone RhoprCAPA-2 that terminates diuresis by inhibiting this synergy. Lateral neurosecretory cells (NSCs) in the mesothoracic ganglionic mass release RhoprCRF/DH, while midline NSCs release RhoprCAPA-2 during blood feeding. These NSCs co-express GPA2/GPB5, a conserved glycoprotein hormone involved in various physiological processes across bilaterians. This study investigated the influence of GPA2/GPB5 signaling on Malpighian tubule (MT) fluid secretion in R. prolixus. GPB5-like immunoreactivity in lateral and midline NSCs decreased following a blood meal, suggesting release and a role in diuresis. Downregulating the GPA2/GPB5 receptor LGR1 via RNA interference resulted in an increased basal fluid secretion rate in MTs, which was inhibited by the antidiuretic hormone RhoprCAPA-2. dsLGR1 treatment reduced the effects of RhoprCRF/DH and 5-HT on MT secretion and eliminated their synergism. RT-qPCR revealed that the expression of the diuretic and antidiuretic hormone receptors decreased in MTs of dsLGR1-injected insects, indicating that GPA2/GPB5 influences the expression of these other receptors. Downregulating LGR1 resulted in a smaller blood meal size and disrupted the normal time course of diuresis. As LGR1 is the most abundantly expressed G protein-coupled receptor gene in R. prolixus MTs, our results suggest that GPA2/GPB5 signaling has a critical role in regulating the timing and success of water retention in the unfed state, and in the complex processes associated with feeding and diuresis in R. prolixus.
在半翅目昆虫红带锥蝽（Rhodnius prolixus）中，餐后成功的利尿过程是通过肽能利尿激素RhoprCRF/DH和生物胺5-羟色胺（5-HT）的协同作用实现的，同时一种抗利尿激素RhoprCAPA-2通过抑制这种协同作用来终止利尿。中胸神经节团中的外侧神经分泌细胞（NSCs）释放RhoprCRF/DH，而中线NSCs在取食血液期间释放RhoprCAPA-2。这些NSCs共表达GPA2/GPB5，这是一种保守的糖蛋白激素，参与两侧对称动物的各种生理过程。本研究调查了GPA2/GPB5信号传导对红带锥蝽马氏管（MT）液体分泌的影响。取食血液后，外侧和中线NSCs中类似GPB5的免疫反应性降低，表明其释放并在利尿中起作用。通过RNA干扰下调GPA2/GPB5受体LGR1导致MTs的基础液体分泌速率增加，但被抗利尿激素RhoprCAPA-2抑制。dsLGR1处理降低了RhoprCRF/DH和5-HT对MT分泌的影响，并消除了它们的协同作用。RT-qPCR显示，在注射dsLGR1的昆虫的MTs中，利尿和抗利尿激素受体的表达降低，表明GPA2/GPB5影响这些其他受体的表达。下调LGR1导致取食血液量减小，并扰乱了正常的利尿时间进程。由于LGR1是红带锥蝽MTs中表达最丰富的G蛋白偶联受体基因，我们的结果表明，GPA2/GPB5信号传导在调节未进食状态下保水的时间和成功以及红带锥蝽与取食和利尿相关的复杂过程中起关键作用。
