Differential regulation of sphingosine kinases 1 and 2 in lung injury.
Differential regulation of sphingosine kinases 1 and 2 in lung injury.
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DOI：
10.1152/ajplung.90357.2008
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发表时间：
2009-04
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影响因子：
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通讯作者：
R. Wadgaonkar;V. Patel;Natalia Grinkina;Carol A Romano;Jing Liu;Yutong Zhao;S. Sammani;Joe G. N. Garcia-Joe
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文献类型：
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作者：
R. Wadgaonkar;V. Patel;Natalia Grinkina;Carol A Romano;Jing Liu;Yutong Zhao;S. Sammani;Joe G. N. Garcia-Joe
两种哺乳动物鞘氨醇激酶（SphK）异构体SphK1和SphK2具有相同的激酶结构域，但具有不同的动力学性质和亚细胞定位，这表明它们在鞘氨醇-1-磷酸（S1P）的产生中具有一个或多个特定的作用。尽管这两种激酶都使用鞘氨醇作为底物产生S1P，但在肺损伤过程中控制SphK激活和随后S1P生成的机制尚不完全清楚。本研究建立小鼠肺损伤模型，探讨lps诱导的SphK1敲除（SphK1(-/-)）和野生型（WT）小鼠肺损伤。我们发现SphK1（-/-）小鼠比WT小鼠更容易受到lps诱导的肺损伤，通过包括细胞因子诱导在内的多个参数进行量化。有趣的是，通过腺病毒载体将WT SphK1过表达到肺中，可以保护SphK1（-/-）小鼠免受肺损伤，并减轻对LPS反应的严重程度。然而，腺病毒在SphK1（-/-）小鼠肺中过度表达SphK1激酶死亡突变体（SphKKD）进一步加剧了对LPS的反应以及肺损伤的程度。WT SphK2腺病毒过表达也不能提供保护，事实上，增加了lps诱导的肺损伤程度。这表明，在血管损伤中，由SphK2激活产生的S1P与依赖sphk1的S1P的产生和生存信号相比起着明显不同的作用。对肺损伤过程中SphK1和SphK2表达水平的芯片和实时RT-PCR分析显示，在WT小鼠中，LPS处理可在6小时内显著提高SphK1表达水平（约5倍），并在处理后24小时回落至基线水平。相比之下，SphK2的表达在LPS处理后逐渐被诱导，并在24小时内升高。总的来说，我们的研究结果首次证明了两种SphK亚型在LPS诱导的肺损伤调节中的不同功能作用。
Two mammalian sphingosine kinase (SphK) isoforms, SphK1 and SphK2, possess identical kinase domains but have distinct kinetic properties and subcellular localizations, suggesting each has one or more specific roles in sphingosine-1-phosphate (S1P) generation. Although both kinases use sphingosine as a substrate to generate S1P, the mechanisms controlling SphK activation and subsequent S1P generation during lung injury are not fully understood. In this study, we established a murine lung injury model to investigate LPS-induced lung injury in SphK1 knockout (SphK1(-/-)) and wild-type (WT) mice. We found that SphK1(-/-) mice were much more susceptible to LPS-induced lung injury compared with their WT counterparts, quantified by multiple parameters including cytokine induction. Intriguingly, overexpression of WT SphK1 delivered by adenoviral vector to the lungs protected SphK1(-/-) mice from lung injury and attenuated the severity of the response to LPS. However, adenoviral overexpression of a SphK1 kinase-dead mutant (SphKKD) in SphK1(-/-) mouse lungs further exacerbated the response to LPS as well as the extent of lung injury. WT SphK2 adenoviral overexpression also failed to provide protection and, in fact, augmented the degree of LPS-induced lung injury. This suggested that, in vascular injury, S1P generated by SphK2 activation plays a distinctly separate role compared with SphK1-dependent S1P generation and survival signaling. Microarray and real-time RT-PCR analysis of SphK1 and SphK2 expression levels during lung injury revealed that, in WT mice, LPS treatment caused significantly enhanced SphK1 expression ( approximately 5x) levels within 6 h, which declined back to baseline levels by 24 h posttreatment. In contrast, expression of SphK2 was gradually induced following LPS treatment and was elevated within 24 h. Collectively, our results for the first time demonstrate distinct functional roles of the two SphK isoforms in the regulation of LPS-induced lung injury.