Reproductive biology of the relaxin-like factor (RLF/INSL3)

Abstract

The relaxin-like factor (RLF), which is the product of the insulin-like factor 3 (INSL3) gene, is a new circulating peptide hormone of the relaxin-nsulin family. In male mammals, it is a major secretory product of the testicular Leydig cells, where it appears to be expressed constitutively but in a differentiation-dependent manner. In the adult testis, RLF expression is a good marker for fully differentiated adult-type Leydig cells, but it is only weakly expressed in prepubertal immature Leydig cells or in Leydig cells that have become hypertrophic or transformed. It is also an important product of the fetal Leydig cell population, where it has been demonstrated using knockout mice to be res..