Differential splicing and expression of the relaxin-like factor gene in reproductive tissues of the marmoset monkey (Callithrix jacchus)

The relaxin-like factor (RLF) is a novel member of the insulin/relaxin/insu lin-like growth factor family of growth factors and hormones that is expres sed predominantly in the reproductive system, with highest expression in th e Leydig cells of the testis. Using a combination of molecular and immunolo gical techniques, we have characterized the structure and expression of the RLF gene from a primate model, the marmoset monkey, with the intention of comparing this with recent results on the closely related hormone relaxin i n this species. As in other species, including the human, RLF gene products can be detected maximally in Leydig cells and in the follicular theca inte rna cells and corpora lutea of the ovary. Reverse transcription-polymerase chain reaction analysis confirmed this expression and showed that in the co rpus luteum, testis, and epididymis, a second, alternative RLF gene transcr ipt was present that is expressed at low levels and that appears to be deri ved by differential splicing of a novel exon. Analysis of genomic DNA from the marmoset showed that in this species, the single-copy gene contains a l onger intronic region separating the two exons described for the human. Alt ernative splicing introduces a novel exon 1A between exons 1 and 2, which l eads to an altered open reading frame, with a new stop codon, such that if translated, the novel transcript will encode a truncated polypeptide compri sing a C-terminally extended B-domain.