Identification, Expression, and Functions of the Somatostatin Gene Family in Spotted Scat (Scatophagus argus)

Peizhe Feng,Siping Deng,Guangli Li,Changxu Tian,Hongjuan Shi,Huapu Chen,Dongneng Jiang,Xinghua Lin,Chunhua Zhu

doi:10.3390/genes11020194

Abstract

Somatostatins (SSTs) are a family of proteins consisting of structurally diverse polypeptides that play important roles in the growth regulation in vertebrates. In the present study, four somatostatin genes (SST1, SST3, SST5, and SST6) were identified and characterized in the spotted scat (Scatophagus argus). The open reading frames (ORFs) of SST1, SST3, SST5, and SST6 cDNA consist of 372, 384, 321, and 333 bp, respectively, and encode proteins of 123, 127, 106, and 110 amino acids, respectively. Amino acid sequence alignments indicated that all SST genes contained conserved somatostatin signature motifs. Real-time PCR analysis showed that the SST genes were expressed in a tissue specific manner. When liver fragments were cultured in vitro with synthetic peptides (SST1, SST2, or SST6 at 1 μM or 10 μM) for 3 h or 6 h, the expression of insulin-like growth factor 1 and 2 (Igf-1 and Igf-2) in the liver decreased significantly. Treatment with SST5 had no significant effect on Igf-1 and Igf-2 gene expression. This study provides an enhanced understanding of the gene structure and expression patterns of the SST gene family in S. argus. Furthermore, this study provides a foundation for future exploration into the role of SST genes in growth and development.

Highlights

Somatostatins (SSTs) are cyclic regulatory peptides that play an important role in reproduction, metabolism, and the growth of vertebrates [1]
Four genes SST1, SST3, SST5, and SST6 were successfully identified in S. argus
The theoretical isoelectric points for these proteins were predicted to be between 5.14 and 9.06 (Table 1). Both SST1 and SST3 were located on linkage group 4 (Table 1), whereas SST5 and SST6 were located on linkage group 23 and linkage group 8, respectively

Summary

Introduction

Somatostatins (SSTs) are cyclic regulatory peptides that play an important role in reproduction, metabolism, and the growth of vertebrates [1]. The expression of SST peptides is predominantly localized to the central nervous system and peripheral nerves, and secondarily in the intestine, stomach, and pancreas. These proteins function as both a hormone and a neurotransmitter [2]. First isolated from an ovine hypothalamus extract by Brazeau in 1973, the SS-14 amino acid was observed to inhibit the secretion of growth hormone (Gh) from the pituitary of rats [3]. In salmon (Salmo salar), secretion of SS-14 from the hypothalamus can inhibit the expression of Igf-1 in the liver [5,6]. In rainbow trout (Oncorhynchus mykiss), the expression of Igf-1 in plasma and liver was reduced by injection of SS-14 [6], Genes 2020, 11, 194; doi:10.3390/genes11020194 www.mdpi.com/journal/genes

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