Mammalian follicle-stimulating hormone and insulin-like growth factor I (IGF-I) up-regulate IGF-I gene expression in organ culture of newt testis.
We previously showed that porcine follicle-stimulating hormone (pFSH) and human recombinant insulin-like growth factor (rhIGF-I) promote the differentiation of secondary spermatogonia into primary spermatocytes in organ cultures of newt testes, respectively. To elucidate the molecular action of FSH and IGF-I, we cloned cDNAs for newt IGF-I and IGF-I receptor (IGF-IR), and examined their mRNA expression in organ culture during newt spermatogenesis. Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses revealed that IGF-I mRNA was highly expressed in somatic cells (mostly Sertoli cells) at the secondary spermatogonial stage but barely in germ cells, and that IGF-IR mRNA was expressed in both germ and somatic cells at all stages examined. The addition of pFSH to newt testis markedly increased IGF-I mRNA expression. Also, rhIGF-I increased IGF-I mRNA expression, whereas IGF-IR mRNA expression declined slightly. These results suggest that the ability of FSH to promote the differentiation of secondary spermatogonia is at least partly mediated by somatic cell-derived IGF-I, and that IGF-I mRNA expression in somatic cells is auto-upregulated.
Yamamoto
T
T
Department of Biological Science, Faculty of Science, Kumamoto University, Kumamoto, Japan.
Nakayama
Y
Y
Abé
S I
SI
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003001:Cloning, Molecular; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics; D012455:Salamandridae; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013091:Spermatogenesis / Q000235:genetics; D013552:Swine; D013737:Testis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D014981:Xenopus
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D017526:Receptor, IGF Type 1