Involvement of Rho-kinase in sphingosine 1-phosphate-stimulated HSP27 induction in osteoblasts.
We previously reported that sphingosine 1-phosphate induces heat shock protein 27 (HSP 27) via activation of phosphatidylinositol 3-kinase (PI3K)/Akt and p38 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether Rho-kinase is implicated in sphingosine 1-phosphate-stimulated induction of HSP27 in MC3T3-E1 cells. Sphingosine 1-phosphate time-dependently induced the phosphorylation of myosin phosphatase targeting subunit (MYPT-1), a Rho-kinase substrate. Y27632, a specific Rho-kinase inhibitor, significantly reduced sphingosine 1-phosphate-stimulated HSP27 induction, as well as MYPT-1 phosphorylation. Fasudil, another inhibitor of Rho-kinase, also suppressed sphingosine 1-phosphate-stimulated HSP27 induction. Y27632, as well as fasudil, attenuated sphingosine 1-phosphate-induced phosphorylation of p38 MAP kinase. However, Akt phosphorylation induced by sphingosine 1-phosphate was not affected by either Rho-kinase inhibitor. These results strongly suggest that Rho-kinase regulates sphingosine 1-phosphate-stimulated induction of HSP27 at a point upstream of p38 MAP kinase in osteoblasts.
Minamitani
Chiho
C
Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
Otsuka
Takanobu
T
Takai
Shinji
S
Matsushima-Nishiwaki
Rie
R
Adachi
Seiji
S
Hanai
Yoshiteru
Y
Mizutani
Jun
J
Tokuda
Haruhiko
H
Kozawa
Osamu
O
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D055551:HSP27 Heat-Shock Proteins / Q000096:biosynthesis*; D008246:Lysophospholipids / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase; D010006:Osteoblasts / Q000378:metabolism*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000577:Amides; D055551:HSP27 Heat-Shock Proteins; C486699:Hspb2 protein, mouse; D008246:Lysophospholipids; D011725:Pyridines; C108830:Y 27632; C060506:sphingosine 1-phosphate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D048051:p38 Mitogen-Activated Protein Kinases; D043263:Myosin-Light-Chain Phosphatase; C510645:Ppp1r12a protein, mouse; D013110:Sphingosine; C049347:fasudil