23rd Conference of European Comparative Endocrinologists edition:23 location:Manchester, UK date:29th August - 2nd September 2006
Neuroparsins (NPs) are members of a peptide family designated as parsins, a category of small neurosecretory proteins intitially discovered from locust pars intercerebralis-corpora cardiaca extracts. We have cloned four desert locust cDNAs each coding for a different neuroparsin precursor (Scg-NPP). Locust neuroparsins display sequence similarities with related peptides in a variety of other arthropod species, as well as with the conserved N-terminal part of vertebrate IGF-binding proteins (IGFBPs). To study the transcriptional regulation of the corresponding genes in several tissues and under different physiological conditions, we have performed 'quantitative real-time RT-PCR' assays. Scg-NPP gene expression appears to be regulated in a tissue-, stage-, gender-, hormone-, and phase-dependent manner. A temporal correlation between the levels of Scg-NPP transcripts and important physiological changes during the hormonally controlled reproduction cycle was revealed in adult locusts. In order to further study the possible functional relationship between NP and insulin-related peptides (IRP), we have produced and purified recombinant Scg-NP4. In addition, and endogenous S. gregaria insulin-related peptide (Scg-IRP) was purified from corpora cardiaca extracts by HPLC. Subsequently, a preliminary binding assay supported our hypothesis that Scg-IRP and Scg-NP4 may be interacting partners. Based on this finding, we propose a new possible model for the insulin-signalling pathway.