Leptin promotes cell survival and activates Jurkat T lymphocytes by stimulation of mitogen-activated protein kinase
Leptin promotes cell survival and activates Jurkat T lymphocytes by stimulation of mitogen-activated protein kinase
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DOI：
10.1111/j.1365-2249.2007.03563.x
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发表时间：
2008-03-01
影响因子：
4.6
通讯作者：
Sanchez-Margalet, V.
中科院分区：
文献类型：
--
作者：
Fernandez-Riejos, P.;Goberna, R.;Sanchez-Margalet, V.
瘦素(Leptin，Ob)是一种非糖基化的多肽激素，不仅能集中调节能量稳态，而且还具有包括免疫功能调节在内的全身性作用。我们以前已经报道过，瘦素可以激活与植物血凝素(PHA)(4微克/毫升)共同刺激的人外周血淋巴细胞，从而阻止了信号通路的药物抑制剂的使用。在目前的研究中，我们使用Jurkat T细胞对瘦素做出反应，同时最小限度地联合刺激PHA(0.25微克/毫升)。瘦素受体的长亚型表达于Jurkat T细胞上，在瘦素刺激下，早期激活标记CD69的表达以剂量依赖的方式增加(0.1-10 nM)。我们还发现，瘦素可以激活Janus家族受体相关的信号转导和转录激活因子(JAK-STAT)、丝裂原激活的蛋白激酶(MAPK)和磷脂酰肌醇3激酶(PI3K)信号通路。此外，我们试图通过无血清培养来研究瘦素对Jurkat T细胞存活和凋亡的可能影响。我们用异硫氰酸荧光素(FITC)标记的膜联蛋白V(Annexin V)与碘化丙啶(PI)的染料排斥法同时检测细胞凋亡的早期阶段。此外，我们还用识别活性caspase-3的特异性抗体免疫印迹法检测了caspase-3的激活水平。我们发现瘦素抑制细胞凋亡的作用呈剂量依赖关系。通过使用药物抑制剂，我们发现瘦素在Jurkat T细胞中的刺激和抗凋亡作用依赖于MAPK激活，而不是PI3K途径，这为瘦素在T细胞中的作用机制提供了新的数据，这可能有助于更好地理解营养状况和免疫功能之间的关系。
Leptin (Ob) is a non-glycosylated peptide hormone that regulates energy homeostasis centrally, but also has systemic effects including the regulation of the immune function. We have reported previously that leptin activates human peripheral blood lymphocytes co-stimulated with phytohaemagglutinin (PHA) (4 mu g/ml), which prevented the employment of pharmacological inhibitors of signalling pathways. In the present study, we used Jurkat T cells that responded to leptin with minimal PHA co-stimulation (0.25 mu g/ml). The long isoform of leptin receptor is expressed on Jurkat T cells and upon leptin stimulation, the expression of early activation marker CD69 increases in a dose-dependent manner (0.1-10 nM). We have also found that leptin activates receptor-associated kinases of the Janus family-signal transucers and activators of transcription (JAK-STAT), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PI3K) signalling pathways. Moreover, we sought to study the possible effect of leptin on cell survival and apoptosis of Jurkat T cells by culture in serum-free conditions. We have assayed the early phases of apoptosis by flow cytometric detection of fluorescein isothiocyanate (FITC)-labelled annexin V simultaneously with dye exclusion of propidium iodide (PI). As well, we have assayed the activation level of caspase-3 by inmunoblot with a specific antibody that recognizes active caspase-3. We have found that leptin inhibits the apoptotic process dose-dependently. By using pharmacological inhibitors, we have found that the stimulatory and anti-apoptotic effects of leptin in Jurkat T cells are dependent on MAPK activation, rather than the PI3K pathway, providing new data regarding the mechanism of action of leptin in T cells, which may be useful to understand more clearly the association between nutritional status and the immune function.