[Effect of BMP-7 on the transdifferentiation of cultured human tubular epithelial cell induced by TGF-beta1].
OBJECTIVE
To observe the effect of bone morphogenetic protein-7 (BMP-7) on the transdifferentiation of cultured human tubular epithelial cell (HKC) induced by TGF-beta1 and to elucidate its possible mechanism.


METHODS
The cultured HKC cells were divided into 5 groups: serum-free group (negative control); single TGF-beta1 treated group (positive control); single BMP-7 treated group; combined TGF-beta1 and BMP-7 treated group; and BMP-7 pre-treated group. Expression of keratin of HKC cells was assessed by indirect enzyme immunohistochemistry (IEI), expression of alpha-smooth muscle actin (alpha-SMA) and E-cadherin by immunohistological method, percentage of alpha-SMA positive HKC cells by flow cytometry, and mRNA expression of alpha-SMA, TGF-beta1, and TGF-beta type II receptor by reverse transcription PCR.


RESULTS
The expression of alpha-SMA and the percentage of alpha-SMA positive HKC cells markedly increased after having been treated by TGF-beta1 while the expression of E-cadherin and keratin decreased. In the group pre-treated with BMP-7 (50 ng/ml) and then added with TGF-beta1 (8 ng/ml), expression of alpha-SMA was significantly lower than in the positive control group, while expression of E-cadherin and keratin significantly higher than in the positive control group. Measurement of the percentage of alpha-SMA positive HKC found significant deference between the combined TGF-beta1 and BMP-7 treated group and the positive control group (9.7% vs 19.8%; 5.8% vs 19.8%; P < 0.05). Significant difference existed between the BMP-7 (50 ng/ml) pre-treated group and the positive control group (8.7% vs 19.8%, P < 0.05). mRNA expression of alpha-SMA was measured by RT-PCR and the results showed that it significantly decreased in the group treated or pre-treated with BMP-7 (50 ng/ml) (15% and 12% of the results in the positive control group, respectively). The mRNA expression levels of both TGF-beta1 and its type II receptor significantly decreased (28% and 19%; 47% and 36%, compared with the positive control group, respectively).


CONCLUSIONS
Transdifferentiation of cultured renal epithelial cell induced by TGF-beta1 can be inhibittd by certain levels of BMP-7, cultured together with TGF-beta1 or pretreated. BMP-7 can prevent and inhibit the mRNA expression of TGF-beta1 and its type II receptor, which may be an important mechanism by which BMP-7 inhibit the transdifferentiation of renal tubular epithelial cell.
Tan
Xiao-yue
XY
Department of Nephrology, PUMC Hospital, CAMS and PUMC, Beijing 100730, China.
Zheng
Fa-lei
FL
Yang
Ji-hong
JH
Duan
Lin
L
Li
Yan
Y
Zhou
Qiu-gen
QG
D000199:Actins / Q000096:biosynthesis / Q000235:genetics; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology*; D006801:Humans; D007684:Kidney Tubules / Q000166:cytology* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
D000199:Actins; C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D012333:RNA, Messenger; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1