Serum-stimulated alpha 1 type IV collagen gene transcription is mediated by TGF-beta and inhibited by estradiol.
We examined the hypothesis that fetal calf serum (FCS) stimulates murine mesangial cell alpha 1 type IV collagen (COL4A1) gene transcription by increasing autocrine production of transforming growth factor-beta (TGF-beta) through a platelet-derived growth factor (PDGF)-dependent mechanisms. PDGF-stimulated COL4A1 gene transcription was inhibited by neutralizing antibody to TGF-beta (119.3 +/- 3.6 vs. 106.0 +/- 6.2 relative luciferase units, expressed as a percentage of control untreated cells, P < 0.003). FCS-stimulated gene transcription was inhibited by neutralizing antibody to PDGF (148.3 +/- 4.1 vs. 136.7 +/- 0.3 relative luciferase units, P < 0.002) and by neutralizing antibody to TGF-beta (148.3 +/- 4.1 vs. 127.1 +/- 3.4 relative luciferase units, P < 0.036). The inhibitory effect of combined treatment with anti-PDGF and anti-TGF-beta antibody on gene transcription was no greater than that of anti-TGF-beta antibody alone [129.5 +/- 0.53 vs. 127.1 +/- 3.4 relative luciferase units, P = not significant (NS)]. FCS-stimulated gene transcription was also inhibited by estradiol (10(-7) M) (148.4 +/- 3.1 vs. 119.4 +/- 8.1 relative luciferase units, P < 0.019). In the presence of estradiol, anti-TGF-beta antibody failed to further reduce serum-stimulated gene transcription (119.4 +/- 8.1 vs. 115.6 +/- 9.8, P = NS), suggesting that estradiol reverses FCS-stimulated COL4A1 gene transcription by antagonizing the actions of TGF-beta. Measurement of type IV collagen synthesis by Western blotting confirmed that the intact gene responded in a manner analogous to the promoter construct.
Lei
J
J
Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York 10467, USA.
Silbiger
S
S
Ziyadeh
F N
FN
Neugarten
J
J
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western; D002417:Cattle; D002461:Cell Line, Transformed; D003094:Collagen / Q000235:genetics*; D003470:Culture Media; D004958:Estradiol / Q000494:pharmacology*; D005312:Fetal Blood; D005920:Glomerular Mesangium / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D051379:Mice; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011993:Recombinant Fusion Proteins; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D000906:Antibodies; D003470:Culture Media; D010982:Platelet-Derived Growth Factor; D011993:Recombinant Fusion Proteins; D016212:Transforming Growth Factor beta; D004958:Estradiol; D003094:Collagen; D008156:Luciferases