肝再生是可控的程序性修复过程，血窦内皮细胞既是信号的响应者，也调控自身与肝实质细胞的增殖，在肝再生中起重要作用。我们前期血窦内皮细胞质膜差异蛋白质组数据显示，肝切除不同时期内皮细胞质膜上特定受体与Src激酶、PKA及PKC依次激活，相应功能蛋白发生量的改变，与已有研究结果Src激酶主要与内皮细胞增殖相关，而PKA可通过激活Src的激酶使之失活并促进血管生成相符。为了深入研究肝再生过程中肝血窦内皮细胞动态调控的信号途径及机制，本项目拟在前期基础上，对肝切除后不同时期的内皮祖细胞进行分泌组研究，以确定血窦内皮细胞上游刺激信号的差异；同时结合免疫印迹、激酶或受体特异性抑制，确定激酶活性与肝再生特定时段的相关性；最后鉴定肝血窦内皮细胞磷酸化蛋白组，以确定关键激酶下游的功能分子靶标及相互关系。从而对肝再生过程中不同阶段肝血窦内皮细胞介导的信号通路上、中、下游与肝再生血管生成可控性的关系进行全面探讨。

Liver regeneration is a controllable repairing process. Liver sinusoidal endothelial cells (LSEC) plays important role in liver regeneration since they are not only the signal responsors and also the initiators of signals. They could regulate the proliferation of hepatocyte and themselves. Our previous work on the plasma membrane protein of LSEC at different stages of liver regeneration showed that, after partial hepatectomy for 36 h, 48 h and 72 h, specific receptors and Src kinase, PKA and PKC on the plasma membrane of LSEC were highly expressed alternatively, accompanied by corresponding changes in the functional proteins. Most importantly, this data is in accordance with published results, i.e., Src is contribute to the proliferation of endothelial cells whereas PKA could inactivate Src through activate the kinase of Src and promote the formation of endothelial vessel. Thus, we speculated that the alternative activation of these signal pathway might direct the progress of liver regeneration. Based on the previous data, we intend to profile the secreted proteins of endothelial progenitor cells, and compare the differentiated expressed mRNA to find out its upstream signals; then using kinase activity assay and the administration of kinase inhibitor in vivo, to investigate the relativity between certain kinase and the specific stage of liver; finally, the phosphoproteomics study of LSEC and bioinformatic analysis might clarify their downstream signaling network and target functional protein. In summary, we plan to clarify the upstream signal, middle key kinases and downstream network of LSEC at different stage of liver regeneration and investigate these signal pathways on the angiogenesis in liver regeneration. We expected that this study might provide clues for the clarification of the controllability of liver regeneration.