肝细胞Ca2+和STAT3信号通路介导“通道酶”TRPM7调控部分肝切除术后肝再生

The loss of regenerative capacity, a common feature of end stage liver diseases, is a leading cause of therapeutic failure. Activation of signal transducer and activator of transcription 3 (STAT3) promotes hepatocyte proliferationafter partial hepatectomy (PHx).The reducedintracellularCa2+ impairs hepatocyte proliferation, whichdelays liver regeneration.Transient receptor potential melastatin 7 (TRPM7) channel is a widely expressed divalent cation channel with protein serine/threonine kinase activity, which is involved in cell proliferation and embryonic development processes. However, the exactly role of TRPM7 in liver regeneration is unclear.Our previous studies showed that The loss of regenerative capacity, a common feature of end stage liver diseases, is a leading cause of therapeutic failure. Transient receptor potential melastatin 7 (TRPM7) channel is a widely expressed divalent cation channel with protein serine/threonine kinase activity, which is involved in kinds of cell proliferation via regulating phosphorylation of signal transducer and activator of transcription 3 (STAT3) and Ca2+. However, the functional role of TRPM7 in hepatocyte proliferation and liver regeneration is unexplored. Our previous studies showed that the enforced high TRPM7 expression promotes hepatocyte proliferation in vitro and TRPM7 mRNA expression is correlated with the proliferation of hepatocyte after PHx in vivo. Activation of STAT3 pathway was elevated the ability of liver regeneration. Moreover, Ca2+ was variated with hepatocyte generation cycle during liver regeneration. Therefore, we hypothesize that TRPM7 promotes hepatocyte proliferation via Ca2+ and STAT3 signaling pathway, enhances liver regeneration. In this proposal, TRPM7 current will be recorded by patch clamp technique after PHx, and the correlation between hepatocyte proliferation and TRPM7 current will also be analyzed. The effects of TRPM7 on liver regeneration will be assessed using mice with lower or higher TRPM7 level in their livers mediated by adenovirus vectors. Moreover, to further investigate the possible mechanisms of TRPM7 function in liver regeneration, hepatocyte Ca2+ and STAT3 signaling pathway will be detected. Taken together, completion of this proposal will characterize the critical function of TRPM7 in liver regeneration, which may provide a novel therapeutic target for the end stage of liver diseases.

肝细胞再生能力不足是晚期肝病的共同特征，也是治疗的难点。TRPM7是一同时具有离子通道和蛋白激酶双重结构的膜蛋白，又名“通道酶”，可直接或间接调控转录因子磷酸化（如STAT3）和/或细胞内Ca2+，促进多种类型的细胞增殖。但其在肝细胞增殖和肝再生中的作用尚不明确。项目组前期研究发现体外过表达TRPM7可促进肝细胞增殖，部分肝切除术（PHx）后TRPM7表达与肝细胞增殖呈正相关，激活STAT3可提高PHx后肝再生，且有报道，肝再生过程中肝细胞Ca2+浓度随增殖周期变化。据此，我们推测TRPM7可能通过调控STAT3或Ca2+信号促进肝细胞增殖，进而提高肝再生。本项目拟采用PHx肝再生动物模型，全细胞膜片钳记录PHx后不同时间点肝细胞中TRPM7电生理特征，应用腺病毒/慢病毒为载体改变TRPM7表达，揭示TRPM7在肝再生的作用及其机制。探索提高肝再生的新靶点，为临床晚期肝病治疗提供新思路。

肝细胞再生能力不足是晚期肝病的共同特征，也是治疗的难点。TRPM7是一同时具有离子通道和蛋白激酶双重结构的膜蛋白，又名“通道酶”，可直接或间接调控转录因子磷酸化和/或细胞内Ca2+，促进多种类型的细胞增殖。但其在肝细胞增殖和肝再生中的作用尚不明确。本项目应用部分肝切除术小鼠肝再生模型，探讨TRPM7调节肝再生的作用以及机制。结果发现，肝再生过程中肝细胞增殖与TRPM7呈正相关，体外过表达TRPM7可促进肝细胞增殖，相反阻断TRPM7通道则抑制肝细胞增殖。进一步研究发现，STAT3磷酸化参与TRPM7调控肝细胞增殖过程，沉默肝细胞TRPM7降低了磷酸化STAT3蛋白水平，而抑制STAT3磷酸化能够进一步减少TRPM7的表达，并抑制肝细胞增殖。。以上研究结果提示TRPM7调控STAT3磷酸化影响肝细胞增殖和肝再生，揭示了TRPM7在肝再生的作用及其机制，为寻找提高肝再生的治疗靶点提供新思路，为晚期肝病的治疗提供新策略。