Buehrer B M, Bardes E S, Bell R M
Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
Biochim Biophys Acta. 1996 Oct 18;1303(3):233-42. doi: 10.1016/0005-2760(96)00092-6.
Sphingosine kinase functions in both the catabolism of sphingosine and in signal transduction pathways utilizing sphingosine-1-phosphate. The regulation of sphingosine kinase activity in human erythroleukemia (HEL) cells was investigated by treatment with several bioactive agents. Treatment of HEL cells with phorbol 12-myristate 13-acetate (PMA) caused a time- and concentration-dependent increase in sphingosine kinase activity measured in vitro. Sphingosine kinase activity increased in a phorbol ester- and diacylglycerol-specific manner. Staurosporine and calphostin C, protein kinase C (PKC) inhibitors, blocked the increased in sphingosine kinase activity, suggesting a PKC-dependent regulation. The effects of PMA on sphingosine kinase were dependent on transcription and translation. Purified PKC had no direct effect on sphingosine kinase activity. However, these studies led to the observation that HEL cell sphingosine kinase activity is stimulated in vitro by phosphatidylserine. Interestingly, other inducers of HEL cell differentiation, dimethylsulfoxide and retinoic acid, did not affect sphingosine kinase activity. These results indicate a separate and distinct pathway of PKC-dependent sphingosine kinase activation, and suggest a role for sphingosine kinase in regulation of cell function.
鞘氨醇激酶在鞘氨醇的分解代谢以及利用1-磷酸鞘氨醇的信号转导途径中均发挥作用。通过用几种生物活性剂处理，研究了人红白血病（HEL）细胞中鞘氨醇激酶活性的调节。用佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）处理HEL细胞，导致体外测定的鞘氨醇激酶活性呈时间和浓度依赖性增加。鞘氨醇激酶活性以佛波酯和二酰基甘油特异性方式增加。蛋白激酶C（PKC）抑制剂星形孢菌素和钙泊三醇C可阻断鞘氨醇激酶活性的增加，提示其受PKC依赖性调节。PMA对鞘氨醇激酶的作用取决于转录和翻译。纯化的PKC对鞘氨醇激酶活性无直接影响。然而，这些研究发现，磷脂酰丝氨酸可在体外刺激HEL细胞鞘氨醇激酶活性。有趣的是，HEL细胞分化的其他诱导剂，如二甲基亚砜和视黄酸，并不影响鞘氨醇激酶活性。这些结果表明存在一条独立且独特的PKC依赖性鞘氨醇激酶激活途径，并提示鞘氨醇激酶在细胞功能调节中发挥作用。
