Characterization of a flatworm inositol (1,4,5) trisphosphate receptor (IP?R) reveals a role in reproductive physiology.

ABSTRACT: Inositol 1,4,5-trisphosphate receptors (IP?Rs) are intracellular Ca²? channels that elevate cytoplasmic Ca²? in response to the second messenger IP3. Here, we describe the identification and in vivo functional characterization of the planarian IP?R, the first intracellular Ca²? channel to be defined in flatworms. A single IP?R gene in Dugesia japonica encoded a 2666 amino acid protein (Dj.IP?R) that shared well conserved structural features with vertebrate IP?R counterparts. Expression of an NH?-terminal Dj.IP?R region (amino acid residues 223-585) recovered high affinity ³H-IP? binding (0.9±0.1 nM) which was abolished by a single point mutation of an arginine residue (R495L) important for IP? coordination. In situ hybridization revealed that Dj.IP?R mRNA was most strongly expressed in the pharynx and optical nerve system as well as the reproductive system in sexualized planarians. Consistent with this observed tissue distribution, in vivo RNAi of Dj.IP?R resulted in a decreased egg-laying behavior suggesting Dj.IP?R plays an upstream role in planarian reproductive physiology.

SUBMITTER: Zhang D 

PROVIDER: S-EPMC3665645 | biostudies-literature | 2013 May-Jun

REPOSITORIES: biostudies-literature