Molecular cloning and tissue distribution profiles of the chicken R-spondin1 gene.

Rspo1 belongs to the Rspo family, which is composed of 4 members (Rspo1-4) that share 40 to 60% sequence homology and similar domain organizations, and regulate the WNT signaling pathway via a common mechanism. Rspo1 plays a key role in vertebrate development and is an effective mitogenic factor of gastrointestinal epithelial cells. We report the cloning of chicken Rspo1 and its gene expression distribution among tissues. It contained an open reading frame of 783 bp encoding a protein of 260 amino acids, and its molecular weight was predicted to be 28.80 kDa. Reverse transcription-polymerase chain reaction-based gene expression analysis indicated that chicken Rspo1 was highly expressed in the stomach muscle tissue, but was expressed at low levels in the lung, brain, jejunum, cecum, ileum, spleen, pancreas, kidney, and glandular stomach. These results suggest that Rspo1 plays a major role in muscular immune protection.