Jd. Kittilson et al., Polygenic expression of somatostatin in rainbow trout, Oncorhynchus mykiss: Evidence of a preprosomatostatin encoding somatostatin-14, GEN C ENDOC, 114(1), 1999, pp. 88-96
Previously we reported the existence of two distinct cDNAs in rainbow trout
that encode for separate preprosomatostatins (PPSS), each containing [Tyr(
7), Gly(10)]-somatostatin-14. In the present study, we used rainbow trout t
o further characterize the polygenic origin of somatostatins (SSs), a pepti
de hormone important in the regulation of growth, development, and metaboli
sm of vertebrates. A two-phase rapid amplification of cDNA ends (RACE)-PCR
was used for the isolation of selected cDNAs. We amplified and sequenced a
ca. 350-bp 3' RACE-PCR fragment. Based upon this sequence we designed a sec
ond gene-specific primer for 5' RACE-PCR which yielded a 452-bp fragment. S
equence analysis revealed a 745-bp cDNA containing the complete 5'-untransl
ated region, a single initiation site 118 bases from the most 5' end, and a
single putative polyadenylation site 17 bases from the most. 3' end that w
as terminated with a polyadenylated tail. The deduced protein is a 114-amin
o acid PPSS molecule that contains a number of putative processing sites, p
otentially yielding a 26-amino acid peptide that could be processed further
to a 14-amino acid peptide identical in structure to mammalian SS-14. Nort
hern analysis revealed that PPSS-I was expressed in the pancreas, stomach,
intestine, and brain of rainbow trout. These results suggest a polygenic or
igin of SS, possibly resulting from gene duplication events prior to the di
vergence of teleosts. (C) 1999 Academic Press.