L-carnitine and taurine synergistically inhibit the proliferation and osteoblastic differentiation of vascular smooth muscle cells.
OBJECTIVE
To investigate the synergistic action of L-carnitine (LC) and taurine (TAU) on the proliferation and osteoblastic differentiation of vascular smooth muscle cells (VSMCs).


METHODS
DNA and protein synthesis of VSMCs were assessed using scintillation counting. Alkaline phosphatase (ALP) activity and calcium content were determined to investigate the effects of LC and TAU on the osteoblastic differentiation and mineralization of VSMCs. TAU uptake by VSMCs was assayed. RNA interference was used to down-regulate the expression of the TAU transporter (TAUT) in rat VSMCs.


RESULTS
LC and TAU synergistically inhibited the proliferation and beta-glycerophosphate (beta-GP)-induced osteoblastic differentiation of VSMCs as evidenced by the decreased [(3)H]thymidine incorporation, ALP activity and calcium deposition. Furthermore, LC stimulated the TAU uptake and TAUT expression in VSMCs. Suppression of TAUT with short hairpin RNA (shRNA) abolished the synergistic action of LC and TAU in VSMCs.


CONCLUSIONS
The synergistic inhibitory action of LC and TAU on the proliferation and osteoblastic differentiation of VSMCs is attributable to the up-regulation of TAUT expression and TAU uptake by LC.
Xie
Hui
H
Institute of Metabolism and Endocrinology, the Second Xiang-Ya Hospital, Central South University, Changsha, China.
Yang
Bing
B
Zhou
Xin-min
XM
Song
Feng-lin
FL
Li
Jian-ming
JM
Zhou
Kang
K
Hu
Wen
W
Peng
Yi-qun
YQ
Tang
Si-yuan
SY
Yuan
Ling-qing
LQ
Xiong
Si-yuan
SY
Liao
Xiao-bo
XB
D000818:Animals; D050197:Atherosclerosis / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002331:Carnitine / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007930:Leucine / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology; D051381:Rats; D013654:Taurine / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism; D000099247:Taurine Transporters
D002118:Calcium; D002331:Carnitine; D004247:DNA; D007930:Leucine; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D013654:Taurine; D013936:Thymidine; D000099247:Taurine Transporters