Mode of action of allatostatins in the regulation of juvenile hormone biosynthesis in the cockroach, Diploptera punctata

Abstract

The FGLamide allatostatins (FGL/ASTs) are a family of neuropeptides with pleiotropic functions, including the inhibition of juvenile hormone (JH) biosynthesis, vitellogenesis and muscle contraction. In the cockroach, Diploptera punctata, thirteen FGLa/ASTs and one allatostatin receptor (AstR) have been identified. However, the mode of action of ASTs in regulation of JH biosynthesis remains unclear. Here, we determined the tissue distribution of Dippu-AstR. And we expressed Dippu-AstR in vertebrate cell lines, and activated the receptor with the Dippu-ASTs. Our results show that all thirteen ASTs activated Dippu-AstR in a dose dependent manner, albeit with different potencies. Functional analysis of AstR in multiple cell lines demonstrated that activation of the AstR receptor resulted in elevated levels of Ca(2+) and cAMP, which suggests that Dippu-AstR can act through the Gαq and Gαs protein pathways. The study on the target of AST action reveals that FGL/AST affects JH biosynthesis prior to the entry of acetyl-CoA into the JH biosynthetic pathway.

Omics approaches to study juvenile hormone synthesis

“…AST-C inhibits JH synthesis by blocking the citrate carrier (CIC) that transports citrate from the mitochondria to the cytosol, obstructing the production of cytoplasmic acetyl-CoA that sustains JH synthesis in the CA of mosquitoes. Similar results were reported for the AST-A inhibition of JH synthesis in cockroaches [69]. Most studies on the activities of JH synthesis regulators have been done in vitro ; validation of these results in vivo will be facilitated by the development of CA-specific expression system that could enable a tissue-specific and time dependent manipulation of gene expression.…”

“…ODEs underscored that in the active CA enzymatic activities were not limiting [77]. Stimulation of JH synthesis with exogenous precursors has been reported for the CA of many insect species [68,69], and it seems that having an excess of enzymes is common in most insects studied.…”

Allatostatin-C reversibly blocks the transport of citrate out of the mitochondria and inhibits juvenile hormone synthesis in mosquitoes

“…The fact that all the enzymes were fully functional revealed that in mosquitoes the Aea AST-C target is located before the entry of acetyl-CoA in the JH pathway. Recently, Huang et al (2014) showed that FGLamide AST inhibits JH III synthesis in D. punctata without modifying transcript levels of enzymes in the JH III biosynthetic pathway. The inhibitory effect was overridden by the addition of acetyl-CoA, mevalonate, diphosphomevalonate or farnesol, confirming that the effect is prior to the entry of precursors into the JH biosynthetic pathway (Huang et al, 2014).…”

“…Recently, Huang et al (2014) showed that FGLamide AST inhibits JH III synthesis in D. punctata without modifying transcript levels of enzymes in the JH III biosynthetic pathway. The inhibitory effect was overridden by the addition of acetyl-CoA, mevalonate, diphosphomevalonate or farnesol, confirming that the effect is prior to the entry of precursors into the JH biosynthetic pathway (Huang et al, 2014). Our results exposed that FGLamide and PISCF ASTs may well have similar mechanisms of action.…”

A potential insect growth regulator for cockroach control: design, synthesis and bioactivity of N‐terminal‐modified allatostatin analogues

“…Chinese hamster ovary (CHO) WTA11 (Euroscreen, Gosselies, Belgium) were cultured as described previously. 25 Transfections with pcDNA3.1D-Dippu-AstR or empty pcDNA3.1D vector (control) were carried out in T75 flasks at 60-80% confluency. After transfection, cells were incubated overnight and an additional 10 mL of culture medium was added.…”