神经生长因子通过TrkA信号途径促进肝细胞增殖

目的: 观察神经生长因子(NGF)及其受体(TrkA^NGFR和p75^NTR)在肝细胞中的表达,探讨外源性神经生长因子 β(NGF-β)对肝细胞的生物学作用。方法: 体外培养L02肝细胞,免疫细胞化学和荧光定量PCR法分别检测NGF、TrkA^NGFR和p75^NTR在L02细胞中的表达。XTT法检测外源性NGF-β、anti-NGF、anti-TrkA^NGFR和anti-p75^NTR对L02细胞增殖的作用,流式细胞术检测外源性NGF-β对L02细胞凋亡和细胞周期的影响。结果: L02细胞表达NGF及其受体TrkA^NGFR、p75^NTR,NGF主要位于细胞质和细胞核,TrkA^NGFR和p75^NTR位于细胞质和细胞 膜;外源性NGF-β上调L02细胞表达NGF和TrkA^NGFR。低剂量外源性NGF-β(12.5~200 μg/L) 通过调控L02细胞的S期,促进细胞增殖,抗细胞凋亡,高剂量(>400 μg/L)NGF-β不能促进L02细胞增殖;anti-NGF和anti-TrkA^NGFR抑制NGF-β诱导的L02细胞增殖,anti-p75^NTR并不影响NGF-β诱导的L02细胞增殖。结论: L02细胞表达NGF及其受体TrkA^NGFR、p75^NTR;合适剂量外源性NGF-β可能通过NGF/TrkA^NGFR信号途径促进L02细胞增殖。

Nerve growth factor promotes proliferation of hepatocytes in vitro via TrkANGFR signal pathway

AIM: To observe the expression and distribution of nerve growth factor(NGF),its high-affinity tyrosine kinase A receptor(TrkANGFR) and low-affinity p75 neurotrophin receptor(p75NTR) in hepatocytes(L02 cells),and to investigate the effects of exogenous recombinant human NGF-β on L02 cells.METHODS: L02 cell line was used in the experiment.The expression and intracellular distribution of NGF,TrkANGFR and p75NTR were detected by the methods of immunocytochemistry and fluorescent quantitative PCR.The proliferation of L02 cells after exposed to exogenous NGF-β,anti-NGF,anti-TrkANGFR and anti-p75NTR was detected by XTT {2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-(phenylamino) carbonyl]-2H-tetrazolium hydroxide} assay.The cell apoptosis and the change of cell cycle of L02 cells after exposed to exogenous NGF-β were determined by flow cytometry with Annexin V-FITC and PI staining.RESULTS: The expression of NGF was mainly localized in the cytoplasm and nuclei of L02 cells.The expression of TrkANGFR was highly and the expression of p75NTR was weakly detected in the cell membrane and cytoplasm of L02 cells.Exogenous NGF-β promoted the expression of NGF and TrkANGFR in L02 cells.Low dose of exogenous NGF-β(12.5-200 μg/L) promoted L02 cell proliferation and inhibited the cell apoptosis by affecting the cell cycle in S-phase.High dose of NGF-β(>400 μg/L) did not promote L02 cell proliferation.Specific neutralizing antibodies of NGF and TrkANGFR decreased the NGF-β-induced proliferation of L02 cells.However,blocking the binding of NGF to p75NTR by anti-p75NTR did not affect the NGF-β-induced proliferation of L02 cells.CONCLUSION: L02 cells express NGF,TrkANGFR and p75NTR.Exogenous recombinant human NGF-β at optimal dose promotes L02 cell proliferation in a dose-dependent manner possibly via NGF/TrkANGFR signal pathway.