Molecular identification of insulin-related peptide receptor and its potential role in regulating development in Pinctada fucata

The insulin-like family is not only an important regulatory factor for animal growth, development, and metabolism, but also a mediator for initiating growth activity of growth hormone. It plays an important role in transferring transmembrane information and regulating cell function by binding to tyrosine kinase receptors (insulin receptors). To better understand the role of insulin-related peptide receptor (Pfirr) on the developmental regulation in Pinctada fucata, 5.326 kb encoding cDNAs for Pfirr have been cloned and functionally characterized. Pfirr displays significant homologies to Crassostrea gigas, and exhibits all the typical features of insulin receptors and tyrosine kinase domain structure, both of which are typical for the protein family sharing high similarity to other orthologs. Real-time PCR analyses show that Pfirr widely expresses in tissues and developmental stages of P. fucata. Expression of Pfirr mRNAs at different developmental stages (polar body stage, the trocophore stage and D-shaped larva stage) following treatment with agonist IGF-I(1, 2, 4 and 8 μM/L) and antagonist PQ401 (5, 15, 25, 50 and 100 μM/L) indicated that Pfirr may be involved in regulating the development of embryos in P. fucata. These results clearly demonstrate Pfirr is involved in regulating developmental process in P. fucata.