Cloning and Functional Identification of Novel Endothelin Receptor Type A Isoforms in Pituitary

Noriyuki Hatae, Nadia Aksentijevich, Hana W. Zemkova, Karla Kretschmannova, Melanija Tomić, Stanko S. Stojilkovic
2007 Molecular Endocrinology  
Mammalian endothelin (ET) receptors, termed ET A R and ET B R, are derived from two intron-containing genes and the functional splice variants of ET B R but not ET A R have been identified. Here, we report about the isolation of cDNAs of ET A R transcripts from rat anterior pituitary, which are generated by alternative RNA splicing. Deletion of exon 2 and insertion of fragments from intron 1 and 2 accounted for formation of three misplaced proteins, whereas the insertion of a fragment from
more » ... fragment from intron 6 resulted in generation of a functional plasma membrane receptor, termed ET A R-C13. In this splice variant, the C-terminal 382S-426N sequence of ET A R was substituted with a shorter 382A-399L sequence, resulting in alteration of the putative domains responsible for coupling to G q/11 and G s proteins and the endocytotic recycling, as well as in deletion of the predicted protein kinase C/casein kinase 2 phosphorylation sites. The mRNA transcripts for ET A R-C13 were identified in normal and immortalized pituitary cells and several other tissues. The pharmacological profiles of recombinant ET A R and ET A R-C13 were highly comparable, but the coupling of ET A R-C13 to the calcium-mobilizing signaling pathway was attenuated, causing a rightward shift in the potency for agonist. Furthermore, the efficacy of ET A R-C13 to stimulate adenylyl cyclase signaling pathway and to internalize was significantly reduced. These results indicate for the first time the presence of a novel ET A splice receptor, which could contribute to the functional heterogeneity among secretory pituitary cell types. (Molecular
doi:10.1210/me.2006-0343 pmid:17312275 fatcat:udarw4t3dzb3jbaldqjgtx3v6u