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Query: UMLS:C1849193 (PSS)
 2,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many bioactive peptides are initially synthesized via larger precursors from which they are released by proteolytic cleavage at basic amino acids. Some precursors contain more than one final product peptide, multiple copies of a single peptide, or both. Different product peptides can be produced from a common precursor in different tissues. It is not currently known whether this cell-type specific production of bioactive peptides is mediated by different, specific propeptide converting enzymes (PCEs) or by a small number of similar PCEs. To resolve this issue for the conversion of prosomatostatin, the processing of prosomatostatin-I (aPSS-I) and prosomatostatin-II (aPSS-II) to either somatostatin-14 (SS-14) or somatostatin-28 (aSS-28), respectively, was examined in anglerfish islets. Two distinct forms of PSS PCE activity were detected using a rapid, sensitive, and specific assay. Examination of the specificity of these two enzyme activities showed that one proteolytic activity performs the aPSS-I to SS-14 conversion, while the other protease liberates aSS-28 from aPSS-II. The SS-14-generating PCE also cleaves aPSS-II to produce [Tyr7,Gly10]SS-14 (a tetra-decapeptide analog of SS-14) and converts proinsulin to insulin. The aSS-28-generating PCE does not process proinsulin. These results provide direct evidence that different, specific PCEs are required for liberation of SS-14 and aSS-28 from their precursors.
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PMID:Direct evidence for two distinct prosomatostatin converting enzymes. Detection using a rapid, sensitive, and specific assay for propeptide converting enzymes. 288 85

Recent advances in the fields of molecular cloning and peptide purification necessitate a reappraisal of our views concerning the evolution of the genes encoding somatostatin-related peptides. The currently widely held view that the genomes of tetrapods contain only the preprosomatostatin-I (PSS-I) gene, encoding somatostatin-14, with a second preprosomatostatin gene being expressed only in teleost fish is no longer tenable. Identification of genes encoding both somatostatin-14 and the somatostatin-related peptide, cortistatin in mammals, identification of the PSS-I and PSS-II preprosomatostatin genes in amphibia, and the isolation of gene products from at least two non-allelic preprosomatostatin genes in lampreys suggests the alternative hypothesis that duplication of the PSS-I gene occurred early in evolution, predating or concomitant with the appearance of the chordates. We speculate that at least two somatostatin genes are expressed in all classes of vertebrates but these genes have evolved at very different rates. It is probable that the preprosomatostatin-II (PSS-II) gene, encoding [Tyr7, Gly10] somatostatin-14 or a related peptide, arose from a second independent duplication of the PSS-I gene in the ancestor of present-day teleost fish at a time after the divergence of the teleost stock from the line of evolution leading to tetrapods. The recent isolation of urotensin II, a peptide which contains a region of structural similarity but is not evolutionarily related to somatostatin-14, from the central nervous systems of lampreys, elasmobranchs and amphibia necessitates that we modify the accepted view that urotensin II is exclusively a product of the caudal neurosecretory system of teleost fish.
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PMID:Somatostatin- and urotensin II-related peptides: molecular diversity and evolutionary perspectives. 917 52

In goldfish, growth hormone (GH) transiently rises 30 min after meals, returning to baseline at 1 h postmeal. Somatostatin (SRIF) is the major inhibitor of GH release. Three cDNAs encoding pre-pro-SRIF (PSS) have been previously cloned from goldfish brain: PSS-I, which encodes SRIF-14; PSS-II, which is potentially processed into gSRIF-28 that has [Glu(1),Tyr(7)(,)Gly(10)]SRIF-14 at the COOH terminus; and PSS-III, which encodes [Pro(2)]SRIF-14 at its COOH terminus. In goldfish, bombesin (BBS), mimicking the endogenous gastrin-releasing peptide (GRP), acutely suppresses food intake and also stimulates GH release. Ghrelin was recently characterized in goldfish as a GH secretagogue and an orexigen. In this paper, we studied the changes in SRIF mRNA levels during feeding and analyzed the influences of BBS and ghrelin peptides on forebrain PSS expression. The results showed a 60% reduction in PSS-II mRNA after meals, but no changes in the expression of PSS-I and PSS-III were found. Intraperitoneal injections of 100 ng/g body wt of BBS increased GH secretion and decreased PSS-I and PSS-II gene expression. Intraperitoneal injection of goldfish ghrelin (100 ng/g body wt) transiently increased the serum GH levels and increased PSS-I, while decreasing PSS-II mRNA levels. Ghrelin (50 ng/g body wt) blocked the effects of BBS (100 ng/g body wt) on PSS-I but not on PSS-II expression. Coadministration of BBS and ghrelin decreased only the PSS-II gene expression. We conclude that the interactions between BBS/GRP and ghrelin can account for the postprandial variations in serum GH levels and the forebrain expression of PSS-II. Furthermore, we demonstrate that intraperitoneal administration of BBS reduces the ghrelin expression levels in the gut. Thus the inhibition of production of ghrelin in the gut may contribute to the satiety effects of BBS/GRP peptides.
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PMID:Periprandial changes in growth hormone release in goldfish: role of somatostatin, ghrelin, and gastrin-releasing peptide. 1574 4