Auernhammer Christoph J, Isele Nicola B, Kopp Florian B, Spoettl Gerald, Cengic Neziha, Weber Matthias M, Senaldi Giorgio, Engelhardt Dieter
Department of Internal Medicine II, Klinikum Grosshadern, Ludwig-Maximilians-Universität, Munich 81366, Germany.
Endocrinology. 2003 Apr;144(4):1202-10. doi: 10.1210/en.2002-220933.
Novel neurotrophin-1/B cell-stimulating factor-3 (NNT-1/BSF-3) is a recently cloned gp130 cytokine, acting through the tripartite ciliary neurotrophic factor receptor (CNTFR) alpha/leukemia inhibitory factor receptor (LIFR)/gp130 receptor complex. The aim of the current study was to investigate the role of NNT-1/BSF-3 in corticotroph cell function and further characterize NNT-1/BSF-3 signaling pathways. Using RT-PCR, expression of ciliary neurotrophic factor receptor alpha, leukemia inhibitory factor receptor, and gp130 could be demonstrated in mRNA derived from murine corticotroph AtT-20 cells and murine pituitary tissue. Incubation of AtT-20 cells with 10 ng/ml recombinant human NNT-1/BSF-3 rapidly induced tyrosine-phosphorylation of signal transducer and activator of transcription (STAT)3 and STAT1 at 5 and 10 min. Proopiomelanocortin promoter activity and suppressor of cytokine signaling (SOCS)-3 promoter activity were significantly stimulated by NNT-1/BSF-3 4.0 +/- 0.3- and 5.9 +/- 0.2-fold, respectively. In comparison with untreated control, NNT-1/BSF-3 significantly stimulated ACTH secretion at 24 and 48 h 1.7 +/- 0.2-fold and 1.5 +/- 0.1-fold above baseline. In comparison with mock-transfected cells, stable overexpression of SOCS-3 in AtT-20 cells abolished NNT-1/BSF-3-induced STAT1 and STAT3 phosphorylation and almost completely inhibited STAT-dependent proopiomelanocortin promoter and SOCS-3 promoter activities. In addition, NNT-1/BSF-3-induced ACTH secretion at 48 h was significantly attenuated by SOCS-3 overexpression. In summary, we have shown that NNT-1/BSF-3 is a modulator of corticotroph cell function, which is negatively regulated by SOCS-3. Our data indicate that the activation of the Jak-STAT cascade is essential for corticotroph NNT-1/BSF-3 signaling. Further studies will have to investigate the possible in vivo role of NNT-1/BSF-3 as a neuroimmunoendocrine modulator of hypothalamus-pituitary-adrenal axis stress response.
新型神经营养因子-1/ B细胞刺激因子-3（NNT-1/ BSF-3）是最近克隆出的一种gp130细胞因子，通过三方睫状神经营养因子受体（CNTFR）α/白血病抑制因子受体（LIFR）/ gp130受体复合物发挥作用。本研究的目的是探讨NNT-1/ BSF-3在促肾上腺皮质激素细胞功能中的作用，并进一步阐明NNT-1/ BSF-3信号通路的特征。利用逆转录聚合酶链反应（RT-PCR），可在源自小鼠促肾上腺皮质激素AtT-20细胞和小鼠垂体组织的mRNA中检测到睫状神经营养因子受体α、白血病抑制因子受体和gp130的表达。用10 ng/ml重组人NNT-1/ BSF-3孵育AtT-20细胞，可在5分钟和10分钟时迅速诱导信号转导子和转录激活子（STAT）3和STAT1的酪氨酸磷酸化。阿黑皮素原启动子活性和细胞因子信号转导抑制因子（SOCS）-3启动子活性分别被NNT-1/ BSF-3显著刺激4.0±0.3倍和5.9±0.2倍。与未处理的对照相比，NNT-1/ BSF-3在24小时和48小时时显著刺激促肾上腺皮质激素（ACTH）分泌，分别比基线水平高1.7±0.2倍和1.5±0.1倍。与mock转染细胞相比，AtT-20细胞中SOCS-3的稳定过表达消除了NNT-1/ BSF-3诱导的STAT1和STAT3磷酸化，并几乎完全抑制了STAT依赖性阿黑皮素原启动子和SOCS-3启动子活性。此外，SOCS-3过表达显著减弱了NNT-1/ BSF-3在48小时时诱导的ACTH分泌。总之，我们已经表明NNT-1/ BSF-3是促肾上腺皮质激素细胞功能的调节剂，其受到SOCS-3的负调控。我们的数据表明，Jak-STAT级联的激活对于促肾上腺皮质激素细胞的NNT-1/ BSF-3信号传导至关重要。进一步的研究将不得不探讨NNT-1/ BSF-3作为下丘脑-垂体-肾上腺轴应激反应的神经免疫内分泌调节剂的可能体内作用。
