Role of TGF-beta1 in bone matrix production in vascular smooth muscle cells induced by a high-phosphate environment.
OBJECTIVE
We demonstrated a relationship between transforming growth factor-beta(1) (TGF-beta(1)) and production of bone matrix in vascular smooth muscle cells (VSMCs) induced by a high-phosphate environment.


METHODS
Rat VSMCs were incubated in a high-phosphate (2.5 or 3.5 mM) or TGF-beta(1) (2 or 5 ng/ml) environment. TGF-beta(1) monoclonal neutralization antibody (50 microg/ml) was added to inhibit the TGF-beta(1) signal in high-phosphate medium. Production of TGF-beta(1) was analyzed by Western blot and real-time PCR. Core binding factor a1 (Cbfa1), osteopontin (OP), collagen type I (Col I) and osteocalcin (OC) was investigated by Western blot and immunofluorescence staining. Mineral deposition was assessed by von Kossa staining and o-cresolphthalein complexone method.


RESULTS
VSMCs transformation induced by high phosphate occurs via an autocrine loop of TGF-beta(1). First, high phosphate stimulated the production of TGF-beta(1) in VSMCs. Second, TGF-beta(1) could induce increased expression of osteoblast-specific transcription factor Cbfa1 and osteogenic molecule in VSMCs. Third, the TGF-beta(1) neutralization antibody largely attenuated the upregulation of Cbfa1 and bone matrix in high-phosphate-stimulated cells. However, neutralization of TGF-beta(1) could not inhibit high-phosphate-induced VSMCs calcification, indicating that TGF-beta(1) was not necessary for the deposition of calcium.


CONCLUSIONS
TGF-beta(1) plays a crucial role in bone matrix production but not calcium deposition in VSMCs induced by a high-phosphate environment, and the blockade of TGF-beta(1) signaling may thus be a therapeutic strategy for use with vascular disease in a high-phosphate environment.
Wang
Ningning
N
Renal Division, Department of Internal Medicine, The First Affiliated Hospital with Nanjing Medical University,Nanjing, PR China. nn_wang@163.com
Wang
Xiaoyun
X
Xing
Changying
C
Sun
Bin
B
Yu
Xiangbao
X
Hu
Jianming
J
Liu
Jia
J
Zeng
Ming
M
Xiong
Mingxia
M
Zhou
Shuqin
S
Yang
Junwei
J
D000818:Animals; D001857:Bone Matrix / Q000378:metabolism; D002113:Calcification, Physiologic / Q000187:drug effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D015675:Osteocalcin / Q000096:biosynthesis; D053495:Osteopontin / Q000096:biosynthesis; D010710:Phosphates / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D015854:Up-Regulation
D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D010710:Phosphates; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D053495:Osteopontin