pp6在T细胞发育和自身免疫病中的作用

Impairment of T-cell development and function frequently results in pathogeneses such as autoimmune diseases endangering human health. Mammalian pp6 gene encodes a catalytic subunit of Ser/Thr protein phosphotase. Researches in lower organisms and with cell lines in past two decades have revealed that pp6 gene plays important roles in the control of cell cycle, apoptosis and DNA damage repair etc. However, the physiological function of pp6 in mammals is not known at all. To investigate the physiological role of mammalian pp6 gene, we have deleted pp6 in mice by gene-targeting. Our preliminary studies have shown that pp6 homozygous mutants are embryonic lethal and conditional deletion of pp6 in thymocytes impairs development function of T cells. The number of αβ T cells is severely reduced due enhance apoptosis while the number of γδ T cells is dramatically increased in pp6F/F;Lck-Cre mice, which display severevery autoimmune diseases. We have also found that pp6 negatively regulates MAPK and NFκB signaling downstream of TCR. To better understand the physiological role of mammalian pp6, we will further, using pp6F/F;Lck-Cre mice as a model, investigate the function of pp6 in the regulation of development and function of γδ T cells, and the molecular mechanisms by which pp6 negatively regulates TCR signaling. We will also further characterize the autoimmune phenotypes of pp6F/F;Lck-Cre mice and elucidate the role of pp6-deficient γδ T cells in the development of autoimmunity in pp6F/F;Lck-Cre mice. The discovery of our study will further our understanding the cause for human autoimmune diseases and shed a light on new diagnostic and therapeutic strategies for autoimmune diseases.

T细胞发育和功能失调常会导致包括自身免疫病等危害人类生命健康的疾病。哺乳动物pp6基因编码Ser/Thr蛋白磷酸酶6催化亚基。过去低等生物和细胞株中的研究揭示pp6基因对细胞周期、凋亡和DNA损伤修复具有重要作用。但pp6在哺乳动物的生理功能一无所知。我们应用基因打靶技术在小鼠中剔除了pp6基因。前期研究显示纯合pp6突变早期胚胎致死，而T细胞条件性剔除pp6导致小鼠胸腺细胞发育失调、外周αβ T细胞因凋亡大量减少而γδ T细胞大量增加，并易患自身免疫病。前期研究还揭示pp6负调控TCR下游MAPK和NFκB信号传导。我们将以T细胞条件性敲除pp6突变小鼠为模型，进一步深入研究pp6对γδ T细胞发育和功能的调控作用，阐明pp6负调控TCR下游信号传导的分子机制，以及pp6缺陷γδ T细胞在自身免疫病中的作用。上述研究将加深自身免疫病发病机制的了解，并为自身免疫病诊疗的新策略提供理论依据。

T细胞发育和功能失调常会导致包括自身免疫病等危害人类生命健康的疾病。哺乳动物pp6基因编码Ser/Thr蛋白磷酸酶6催化亚基。pp6在哺乳动物的生理功能一无所知。我们应用基因打靶技术我们在小鼠中剔除了pp6基因。我们的研究显示纯合pp6突变早期胚胎致死，而T细胞条件性剔除pp6导致小鼠(pp6F/F; Lck-Cre)胸腺细胞发育失调、外周αβ T细胞因凋亡大量减少而γδ T细胞大量增加。以 pp6F/F; Lck-Cre小鼠为模型我们深入研究了pp6 基因在αβ T细胞和γδ T细胞发育中的功能以及作用的机制。我们的研究显示：(1)pp6 基因缺陷导致T细胞中TCR远端信号如MAPK和NF−κB等信号通路的过激活;(2)TCR远端信号上调导致αβ T细胞发育过程中的正选择和负选择作用都增强，从而导致αβ T细胞数急剧下降。同时TCR远端信号上调还促进T细胞的前体细胞向γδ T细胞分化和增殖，从而导致γδ T细胞数大量增加；(3)pp6 缺陷还导致ART-mTor信号通路的信号上调，从而导致αβ T细胞的过度激活以及存活力降低；(4)pp6F/F; Lck-Cre小鼠易患自身免疫病，该小鼠的调节性T细胞(Tregs)的数量和比例都急剧减少；(5) 应用蛋白质质谱分析发现了一批PP6蛋白磷酸酶的互作蛋白，并用IP-Western验证其中两个分子与PP6蛋白的互作。我们的研究揭示pp6在T细胞发育中的功能，初步阐述了pp6负调控TCR信号传导的分子机制。我们的研究还为进一步研究pp6基因在自身免疫病中的作用提供了一个新的动物模型。进一步研究将加深对自身免疫病发病机制的了解，并可能为自身免疫病诊疗的新策略提供理论依据。