Molecular analysis of lipid rafts involved in T-cell acrivation

为了研究参与t细胞活化的脂质筏的分子基础，我们检查了脂质筏在t细胞受体信号的年龄相关下降中的变化。通过分析衰老对静息小鼠CD4^+ T细胞脂筏成分的影响，我们发现PAG（一种与鞘糖脂富集微域相关的磷酸化蛋白）显著的年龄依赖性减少。PAG通过将ssk （sks的负调节因子）募集到脂质筏中参与Src家族激酶（SFKs）的调节。这种减少是T细胞特有的，至少部分归因于其mRNA水平的降低。PAG的减少伴随着向脂质筏募集Csk的明显损伤，导致sfk活性失调。SFK负调控系统中的这种缺陷可能与t细胞受体信号的年龄依赖性下降有关。在上述分析的基础上，我们开发了一种方法来观察培养细胞中富含胆固醇的微结构域中的胆固醇。这种方法将有助于监测细胞信号传递过程中脂筏的动态行为。

To study the molecular basis of lipid rafts involved in T-cell activation, we examined the alterations of lipid rafts in an age-associated decline in T-cell receptor signaling. By analyzing the effect of aging on the constituents of lipid rafts in resting mouse CD4^+ T cells, we found a pronounced, age-dependent reduction in PAG (a phosphoprotein associated with glycosphingolipid-enriched microdomains). PAG is involved in the regulation of Src family kinases(SFKs) by recruiting Csk (a negative regulator of SFKs) to lipid rafts. This reduction is specific for T cells and is attributed, at least in part, to the reduction in its mRNA level. The reduction of PAG accompanies marked impairment in recruiting Csk to lipid rafts, resulting in dysregulation of SFKs' activities. This defect in a negative SFK regulatory system may be related to the age-dependent decline in T-cell receptor signaling. Along with the above analyses, we developed a method to visualize cholesterol in cholesterol-rich microdomains in cultured cells. This method will be useful to monitor the dynamic behavior of lipid rafts during cell signaling.