Molecular cloning, characterization and tissue specificity of the expression of the ovine CSRP2 and CSRP3 genes from Small-tail Han sheep (Ovis aries).

Two genes, cysteine- and glycine-rich protein 2 (CSRP2) and cysteine- and glycine-rich protein 3 (CSRP3), play important roles in tissue-specific cell growth and development. However, few CSRP2 and CSRP3 genes have been functionally characterized in sheep. In this study, the full-length cDNAs of the CSRP2 and CSRP3 genes were cloned from Small-tail Han sheep by rapid amplification of cDNA ends-PCR. The GenBank accession numbers of the full-length CSRP2 and CSRP3 cDNA sequences are KJ743957 and KJ743958, respectively. The full-length cDNA of ovine CSRP2 was 917bp, with a 582-bp open reading frame encoding 193 amino acids. The complete ovine CSRP3 cDNA was 917bp, with a 585-bp open reading frame encoding 194 amino acids. Alignment and phylogenetic analyses revealed that their amino acid sequences are highly similar to those of other vertebrates, all of which contain two conserved LIM-only domains and a relatively conserved nuclear targeting sequence. To further validate the functions of the two genes, their mRNA expression patterns were evaluated in various Small-tail Han and Dorper sheep tissues using qRT-PCR analyses. CSRP2 was mainly detected in the aorta, whereas CSRP3 was highly concentrated in the heart and the muscle. CSRP3 was expressed to a higher level in the hearts of Small-tail Han sheep than in Dorper sheep (P<0.05). However, the opposite was found in the muscle (the longissimus dorsi and biceps femoris); CSRP3 was expressed to a higher level in Dorper sheep than in Small-tail Han sheep (P<0.05). We quantified the CRP3 protein (coded by the CSRP3 gene) levels in different tissues in Small-tail Han and Dorper sheep. We also detected a putative isoform of the CRP3 protein in sheep, which was significantly different in the heart tissue of the two breeds (P<0.05). The expression patterns of the two genes' mRNAs and CRP3 protein showed clear tissue specificity in both sheep breeds.