A NOVEL PEPTIDE FROM THE GROWTH-HORMONE RELEASING HORMONE GENE STIMULATES SERTOLI-CELL ACTIVITY

The growth hormone releasing hormone (GHRH) gene is believed to produc e a single functional peptide, GHRH (1). Although GHRH mRNA and peptid e have been identified in various tissues, the only accepted function of GHRH is the stimulation of pituitary growth hormone. We have discov ered that the GHRH mRNA encodes a second peptide that is abundant in t esticular germ cells and specifically activates Sertoli cell expressio n of stem cell factor (SCF), a factor crucial for the normal progressi on of spermatogenesis (2). These observations suggest that the GHRH ge ne produces two distinct peptides, each with tissue-specific activitie s.