Tokuda H, Niwa M, Ishisaki A, Nakajima K, Ito H, Kato K, Kozawa O
Department of Pharmacology, Gifu University School of Medicine, Gifu 500-8705, Japan.
Prostaglandins Leukot Essent Fatty Acids. 2004 May;70(5):441-7. doi: 10.1016/j.plefa.2003.09.006.
We have reported that prostaglandin F2(alpha) (PGF2(alpha)) activates p44/p42 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells, and that p44/p42 MAP kinase plays a role in the PGF2(alpha)-induced heat shock protein 27 (HSP27). In the present study, we investigated the involvement of stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), a member of the MAP kinase superfamily, in PGF2(alpha)-induced HSP27 in MC3T3-E1 cells. PGF2(alpha) time dependently induced the phosphorylation of SAPK/JNK. SP600125, a specific inhibitor of SAPK/JNK, markedly reduced the PGF2(alpha)-stimulated HSP27 accumulation. The inhibitory effect of SP600125 was dose dependent in the range between 0.1 and 30 microM. SP600125 reduced the PGF2(alpha)-increased level of HSP27 mRNA. SP600125 suppressed the phosphorylation of SAPK/JNK induced by PGF2(alpha), but did not affect the PGF2(alpha)-induced phosphorylation of p44/p42 MAP kinase. On the other hand, PD98059, a specific inhibitor of the upstream kinase of p44/p42 MAP kinase, which reduced the phosphorylation of p44/p42 MAP kinase stimulated by PGF2(alpha), had little effect on the PGF2(alpha)-induced phosphorylation of SAPK/JNK. These results strongly suggest that SAPK/JNK plays a part in PGF2(alpha)-induced HSP27 in addition to p44/p42 MAP kinase in osteoblasts.
我们曾报道过，前列腺素F2α（PGF2α）可激活成骨细胞样MC3T3-E1细胞中的p44/p42丝裂原活化蛋白（MAP）激酶，且p44/p42 MAP激酶在PGF2α诱导的热休克蛋白27（HSP27）中发挥作用。在本研究中，我们调查了丝裂原活化蛋白激酶超家族成员之一的应激激活蛋白激酶（SAPK）/c-Jun氨基末端激酶（JNK）在PGF2α诱导MC3T3-E1细胞产生HSP27过程中的作用。PGF2α可时间依赖性地诱导SAPK/JNK磷酸化。SP600125是一种SAPK/JNK的特异性抑制剂，它能显著降低PGF2α刺激引起的HSP27积累。SP600125的抑制作用在0.1至30微摩尔范围内呈剂量依赖性。SP600125降低了PGF2α升高的HSP27 mRNA水平。SP600125抑制了PGF2α诱导的SAPK/JNK磷酸化，但不影响PGF2α诱导的p44/p42 MAP激酶磷酸化。另一方面，PD98059是p44/p42 MAP激酶上游激酶的特异性抑制剂，它能降低PGF2α刺激引起的p44/p42 MAP激酶磷酸化，但对PGF2α诱导的SAPK/JNK磷酸化影响很小。这些结果有力地表明，在成骨细胞中，除了p44/p42 MAP激酶外，SAPK/JNK在PGF2α诱导HSP27过程中也发挥作用。
