title: Type IV collagen induces down-regulation of steroidogenic response to gonadotropins in adult rat Leydig cells involving mitogen-activated protein kinase.
abstract: We have previously shown that type IV collagen (alpha1 (IV) and alpha2 (IV) collagen chains) (Col-IV) inhibits testosterone (T) production by Leydig cells (LC). The aim of this study was to analyze mechanism/s by which Col-IV exerts this effect. No significant differences in the specific binding of hCG to LH/hCG receptors in LC cultured on uncoated or Col-IV coated plates were observed. An inhibition of cAMP production in hCG-stimulated LC cultured on Col-IV was detected. The inhibition exerted by Col-IV on T production in response to hCG was also observed when cells were stimulated with 8Bromo-cAMP. In addition, conversion of steroid precursors to T in LC cultured on uncoated and Col-IV coated plates was similar. On the other hand, we detected an increase of ERK1/2 phosphorylation in hCG-stimulated LC cultured on Col-IV. Genistein added to LC cultures reduced the ability of Col-IV to increase ERK1/2 phosphorylation and reverted the inhibitory effect of Col-IV on T production. An inhibitor of MEK, PD98059 added to LC cultures also reverted the inhibitory effect of Col-IV on T production. A decrease of steroidogenic acute regulatory protein (StAR) expression in hCG-stimulated LC cultured on Col-IV coated plates that could be reverted by addition of PD98059 to the cultures was also demonstrated. All together these results suggest that Col-IV inhibits T production in LC by binding to integrins, activating ERK1/2, decreasing cAMP production and decreasing StAR expression.
authors.affiliation: Centro de Investigaciones en Reproducción, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, (C 1121 ABG) Buenos Aires, Argentina.
authors.forename: Emilce S
authors.initials: ES
authors.lastname: Diaz
authors.forename: Eliana
authors.initials: E
authors.lastname: Pellizzari
authors.forename: Marta
authors.initials: M
authors.lastname: Casanova
authors.forename: Selva B
authors.initials: SB
authors.lastname: Cigorraga
authors.forename: Berta
authors.initials: B
authors.lastname: Denduchis
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism; D024141:Collagen Type IV / Q000494:pharmacology*; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006062:Gonadotropins / Q000378:metabolism*; D006801:Humans; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D011974:Receptors, LH / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D006063:Chorionic Gonadotropin; D024141:Collagen Type IV; D005419:Flavonoids; D006062:Gonadotropins; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D011974:Receptors, LH; D013256:Steroids; D000098682:Steroidogenic Acute Regulatory Protein; D013739:Testosterone; D019833:Genistein; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one