Meeting Abstract

93.1  Sunday, Jan. 6  A newly identified IGFBP in crayfish: another piece in the insulin-like androgenic hormone’s puzzle? ROSEN, O.*; MANOR, R.; WEIL, S.; SAGI, A.; Ben Gurion University of the Negev; Ben Gurion University of the Negev; Ben Gurion University of the Negev; Ben Gurion University of the Negev roseno@post.bgu.ac.il

In malacosracan crustaceans, male sexual differentiation is known to be induced and also maintained by a secreted insulin-like androgenic gland hormone (IAG). The involvement of this peculiar insulin-like factor was thoroughly examined using RNAi in decapods in which silencing several IAG orthologs induced dramatic phenotypic changes ranging from de-masculinization to even male sex-reversal into fully functional female. As of this moment, binding proteins modulating this hormone’s signal (e.g., receptor, carrier etc.) were not documented in Crustacea. In the screening process of an AG cDNA library of the red claw crayfish, Cherax quadricarinatus, an EST encompassing a deduced insulin binding domain was identified. This transcript was found to be expressed in all examined tissues using RT-PCR. Upon full sequencing and bioinformatic analysis, it was found to encode an insulin-like growth factor binding protein (IGFBP) in this crayfish (Cq-IGFBP). Specifically, this deduced protein demonstrates structural homology to the seventh member of the IGFBP family (IGFBP-7). In many cases, members of this family were found to inhibit the action of their IGF-like ligand activity, possibly by their extreme specificity and selective binding which exceeds those of the corresponding insulin-like receptors by more the one/two orders of magnitude. Characterizing the potential link between the crayfish insulin-like androgenic hormone and the newly identified Cq-IGFBP was attempted both by RNAi and protein-protein interaction assays.