Evaluation of intracellular signalling pathways in response to insulin-like growth factor I in apoptotic-resistant activated human hepatic stellate cells.
Evaluation of intracellular signalling pathways in response to insulin-like growth factor I in apoptotic-resistant activated human hepatic stellate cells.
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DOI：
10.1186/1755-1536-2-1
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发表时间：
2009-01-30
期刊：
影响因子：
--
通讯作者：
Pinzani, Massimo
中科院分区：
文献类型：
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作者：
Gentilini, Alessandra;Lottini, Benedetta;Brogi, Marco;Caligiuri, Alessandra;Cosmi, Lorenzo;Marra, Fabio;Pinzani, Massimo
人类肝星状细胞已被证明是抗凋亡刺激。这可能依赖于这些细胞向肌纤维母细胞样细胞转变时抗凋亡途径的激活。特别是，以前的研究已经证明了在肝星状细胞表型从静止到肌纤维母细胞样细胞的转变过程中，抗凋亡蛋白Bcl-2的表达增加，促凋亡蛋白Bax的表达减少。然而，在慢性伤口愈合过程中所涉及的多肽生长因子引起的其他关键抗凋亡和存活途径的作用和表达仍有待阐明。特别是，胰岛素生长因子-I促进活化的人肝星状细胞的趋化和促有丝分裂作用，这些作用是由PI 3-K的活化介导的。胰岛素生长因子-I作为人肝星状细胞存活因子的作用有待证实。本研究的目的是评估其他关键的抗凋亡途径如PI-3 K/Akt/p-Bad对胰岛素生长因子-I的反应。胰岛素生长因子-I诱导Akt活化，随后在孵育15分钟后Bad磷酸化。这些作用是PI-3 k依赖性的，因为该分子的选择性抑制剂渥曼青霉素和LY 294002可以抑制Akt和Bad磷酸化。还研究了胰岛素生长因子-I对Akt活化的两个下游靶点即GSK 3和FHKR的活化的影响，这两个靶点都涉及促进细胞存活。孵育15分钟后，两种靶点都被磷酸化，这些作用也是PI-3 K依赖性的。尽管这种生存途径的激活，胰岛素生长因子-I没有显着的生物学效应，可能是因为其他胰岛素生长因子-I-独立的生存途径已经最大限度地激活肝星状细胞活化的过程中。然而，孵育后的细胞与一个强大的凋亡刺激，如Fas配体+放线菌酮，一小部分肝星状细胞经历程序性细胞死亡，胰岛素生长因子-I部分获救。除了Bcl-2，其他几种抗凋亡途径是负责人肝星状细胞抗凋亡。这些特征与人类肝纤维化的进展和有限的可逆性相关。
Human hepatic stellate cells have been shown to be resistant to apoptotic stimuli. This is likely dependent on the activation of anti-apoptotic pathways upon transition of these cells to myofibroblast-like cells. In particular, previous studies have demonstrated an increased expression of the anti-apoptotic protein Bcl-2 and a decreased expression of the pro-apoptotic protein Bax during the transition of the hepatic stellate cell phenotype from quiescent to myofibroblast-like cells. However, the role and expression of other key anti-apoptotic and survival pathways elicited by polypeptide growth factors involved in the chronic wound healing process remain to be elucidated. In particular, insulin growth factor-I promotes chemotactic and mitogenic effects in activated human hepatic stellate cells and these effects are mediated by the activation of PI 3-K. The role of insulin growth factor-I as a survival factor in human hepatic stellate cells needs to be substantiated. The aim of this study was to evaluate the involvement of other key anti-apoptotic pathways such as PI-3K/Akt/p-Bad in response to insulin growth factor-I. Insulin growth factor-I induced activation of Akt followed by Bad phosphorylation after 15 minutes of incubation. These effects were PI-3k dependent since selective inhibitors of this molecule, wortmannin and LY294002, inhibited both Akt and Bad phosphorylation. The effect of insulin growth factor-I on the activation of two downstream targets of Akt activation, that is, GSK3 and FHKR, both implicated in the promotion of cell survival was also investigated. Both targets became phosphorylated after 15 minutes of incubation, and these effects were also PI-3K-dependent. Despite the activation of this survival pathway insulin growth factor-I did not have a remarkable biological effect, probably because other insulin growth factor-I-independent survival pathways were already maximally activated in the process of hepatic stellate cell activation. However, after incubation of the cells with a strong apoptotic stimuli such as Fas ligand+cycloheximide, a small percentage of hepatic stellate cells underwent programmed cell death that was partially rescued by insulin growth factor-I. In addition to Bcl-2, several other anti-apoptotic pathways are responsible for human hepatic stellate cell resistance to apoptosis. These features are relevant for the progression and limited reversibility of liver fibrosis in humans.