Russo V C, Metaxas S, Kobayashi K, Harris M, Werther G A
Centre for Hormone Research, Murdoch Childrens Research Institute, Parkville 3052, Victoria, Australia.
Endocrinology. 2004 Sep;145(9):4103-12. doi: 10.1210/en.2003-1767. Epub 2004 May 27.
Many factors regulate nervous system development, including complex cross-talk between local neuroendocrine systems. The adipocyte-secreted hormone leptin, mainly known for its key roles in nutrition and reproductive balance, may also be involved in neuroanatomical organization, myelination processes, and neuronal/glia maturation. SK-N-SH-SY5Y neuroblastoma cells were employed as an in vitro model of human neuronal cells to determine whether leptin exerts neuroprotective activities. We show that SH-SY5Y cells express leptin, the long and short isoforms of the leptin receptor (ObRl, ObRs). In SH-SY5Y cells, leptin induced signal transducer and activator of transcription (STAT)-3 phosphorylation and suppressor of cytokine signaling-3 mRNA expression. Leptin dose-dependently increased cell number (up to 200% at 1 microm by 48 h, P < 0.01), and at 24-48 h, leptin at 100 nm increased SH-SY5Y cell number by 30-50%, respectively. SH-SY5Y cell viability was reduced in serum-free conditions at 24 h, and addition of leptin at 100 nm significantly reduced apoptosis by approximately 20% (P < 0.001). Leptin's antiapoptotic activity required Janus kinase/STAT, MAPK, and phosphatidylinositol-3-kinase activation because the antiapoptotic effects of leptin were abolished, and caspase-3 immunoreactivity increased in the presence of the specific blockers AG490, U0126, or LY294002. Gene array demonstrated that leptin inhibits apoptosis via potent down-regulation of caspase-10 and TNF-related apoptosis-inducing ligand. Our data thus demonstrate, for the first time, that leptin stimulates, in a time- and dose-dependent manner, neuroblastoma cell proliferation and that the underlying mechanisms involve suppression of apoptosis via the Janus kinase-STAT, phosphatidylinositol-3 kinase, and MAPK pathways that culminate altogether in the down-regulation of the apoptotic factors caspase-10 and TNF-related apoptosis-inducing ligand.
许多因素调节神经系统发育，包括局部神经内分泌系统之间复杂的相互作用。脂肪细胞分泌的激素瘦素，主要因其在营养和生殖平衡中的关键作用而闻名，也可能参与神经解剖组织、髓鞘形成过程以及神经元/神经胶质细胞成熟。SK-N-SH-SY5Y神经母细胞瘤细胞被用作人类神经元细胞的体外模型，以确定瘦素是否发挥神经保护作用。我们发现SH-SY5Y细胞表达瘦素、瘦素受体的长、短异构体（ObRl、ObRs）。在SH-SY5Y细胞中，瘦素诱导信号转导和转录激活因子（STAT）-3磷酸化以及细胞因子信号抑制因子-3 mRNA表达。瘦素剂量依赖性地增加细胞数量（48小时时1微摩尔浓度下增加高达200%，P<0.01），在24至48小时时，100纳米浓度的瘦素分别使SH-SY5Y细胞数量增加30%至50%。在无血清条件下24小时时SH-SY5Y细胞活力降低，添加100纳米浓度的瘦素可使凋亡显著减少约20%（P<0.001）。瘦素的抗凋亡活性需要Janus激酶/STAT、丝裂原活化蛋白激酶（MAPK）和磷脂酰肌醇-3激酶激活，因为在特异性阻滞剂AG490、U0126或LY294002存在时，瘦素的抗凋亡作用被消除，且半胱天冬酶-3免疫反应性增加。基因芯片显示瘦素通过强力下调半胱天冬酶-10和肿瘤坏死因子相关凋亡诱导配体来抑制凋亡。因此，我们的数据首次证明，瘦素以时间和剂量依赖性方式刺激神经母细胞瘤细胞增殖，其潜在机制包括通过Janus激酶-STAT、磷脂酰肌醇-3激酶和MAPK途径抑制凋亡，这些途径共同导致凋亡因子半胱天冬酶-10和肿瘤坏死因子相关凋亡诱导配体的下调。
