Direct stimulatory effects of insulin-like growth factor-I (IGF-I) on nuclear RNA polymerase II activity and overall protein synthesis in immature rat Sertoli cells.
A large body of evidence support the existence of an intratesticular Insulin-like Growth Factor I (IGF-I) system that can be viewed as a positive regulator of testicular functions. IGF-I may act at the testis level as a paracrine and autocrine differentiating factor. In the present study the role of IGF-I on Sertoli cell protein synthesis at transcriptional level has been investigated by evaluating the effect of IGF-I on nuclear RNA polymerase II activity as well as on total protein synthesis. Sertoli cells isolated from midpubertal rats and cultured in the presence of physiological doses of IGF-I showed a significant increase in nuclear RNA polymerase II activity (+80%) which appears to be correlated with a 50% increase in overall protein synthesis and a 40% increase in Androgen Binding Protein (ABP) production. These data provide the first evidence for a conceivable role of IGF-I in the modulation of Sertoli cell development through a direct action at the transcriptional level resulting in augmented protein synthesis.
Palmero
S
S
Istituto di Fisiologia Generale, Università degli Studi di Genova.
Bardi
G
G
Bolla
F
F
Fugassa
E
E
D000727:Androgen-Binding Protein / Q000096:biosynthesis*; D000818:Animals; D015415:Biomarkers; D002467:Cell Nucleus / Q000187:drug effects* / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D004789:Enzyme Activation; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008297:Male; D012319:RNA Polymerase II / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012708:Sertoli Cells / Q000187:drug effects* / Q000378:metabolism
D000727:Androgen-Binding Protein; D015415:Biomarkers; D007334:Insulin-Like Growth Factor I; D012319:RNA Polymerase II