J. Lei et al., SERUM-STIMULATED ALPHA(1) TYPE-IV COLLAGEN GENE-TRANSCRIPTION IS MEDIATED BY TGF-BETA AND INHIBITED BY ESTRADIOL, American journal of physiology. Renal, fluid and electrolyte physiology, 43(2), 1998, pp. 252-258
We examined the hypothesis that fetal calf serum (FCS) stimulates muri
ne mesangial cell alpha(1) type IV collagen (COL4A1) gene transcriptio
n by increasing autocrine production of transforming growth factor-bet
a (TGF-beta) through a platelet-derived growth factor (PDGF)-dependent
mechanism. PDGF-stimulated COL4A1 gene transcription was inhibited by
neutralizing antibody to TGF-beta (119.3 +/- 3.6 vs. 106.0 +/- 6.2 re
lative luciferase units, expressed as a percentage of control untreate
d cells, P < 0.003). FCS-stimulated gene transcription was inhibited b
y neutralizing antibody to PDGF (145.3 +/- 4.1 vs. 136.7 +/- 0.3 relat
ive luciferase units, P < 0.002) and by neutralizing antibody to TGF-b
eta (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 a
nti-TGF-beta antibody on gene transcription was no greater than that o
f anti-TGF-beta antibody alone [129.5 +/- 0.53 as, 127.1 +/- 3.4 relat
ive luciferase units, P = not significant (NS)]. FCS-stimulated gene t
ranscription 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 prese
nce of estradiol, anti-TGF-beta antibody failed to further reduce seru
m-stimulated gene transcription (119.4 +/- 8.1 vs. 115.6 +/- 9.8, P =
NS), suggesting that estradiol reverses FCS-stimulated COL4A1 gene tra
nscription by antagonizing the actions of TGF-beta. Measurement of typ
e IV collagen synthesis by Western blotting confirmed that the intact
gene responded in a manner analogous to the promoter construct.