高密度脂蛋白亚类与蛋白激酶C活性的关系

目的：观察高密度脂蛋白（HDL）亚类与外周细胞和肝细胞HDL受体结合活性及细胞PKC活性的关系。方法： 以纯化的前β1-HDL及不含apoE的HDL3为配体，分别与人动脉平滑肌细胞（SMC）和肝癌细胞系HepG2反应，观察两种细胞HDL受体结合活性及细胞PKC活性的变化。结果： 前β1-HDL与SMC HDL受体的亲和力不仅显著高于不含apoE的HDL3与SMC HDL受体的亲和力（P＜0.05），而且还显著高于它与HepG2细胞HDL受体的亲和力（P＜0.05）；前β1-HDL和不含apoE的HDL3分别与SMC反应后，均可激活细胞PKC信号传递途径，且前β1-HDL的作用较不含apoE的HDL3更为明显；而这二种HDL亚类分别与HepG2细胞反应后，细胞PKC活性均无明显变化。结论： 前β1-HDL似乎可以比不含apoE的HDL3更为有效的促进细胞胆固醇移出，而且血浆中前β1-HDL可能更多地作用于外周细胞如SMC，并通过外周细胞膜上的HDL受体介导激活PKC信号传递途径，从而促进外周细胞中过剩的胆固醇移出，而肝细胞HDL受体介导的胆固醇进入细胞可能与PKC信号途径无关。

High density lipoprotein subclasses and activities of protein kinase C

AIM: To investigate the relationship between high density lipoprotein (HDL) subclasses and the binding activities of hepatic cell and extra-hepatic cell HDL receptor and intracellular protein kinase C (PKC). METHODS: Using purified pre-β1 HDL and apoE-deficent HDL3 to react with human smooth muscle cells (SMC) and HepG2 cells, then the activities of pre-β1HDL and apoE-deficent HDL3 binding to SMC and HepG2 cells, and the effects of this two HDL subclasses on PKC activities in SMC and HepG2 cells were observed . RESULTS: The results showed that the value of Kd of pre-β1HDL binding to SMC HDL receptor was not only significantly lower than that of apoE-deficient HDL3 (P<0.05), but significantly lower than pre-β1 HDL binding to HepG2 HDL receptor (P<0.05). Cell PKC system was all activated by binding of the two HDL subclasses with SMC HDL receptor, and the effect of pre-β1HDL appeared to be stronger than apoE-deficent HDL3. No change in HepG2 cell PKC activity by binding the two HDL subclasses with HepG2 HDL receptor was observed. CONCLUSIONS: The results indicate that the ability of pre-β1HDL to promote efflux of cholesterol from extra-hepatic cells is stronger than that of apoE-deficent HDL3, and it seems that plasma pre-β1 HDL mainly interacts with extra-hepatic cell HDL receptor, subsequently, activates PKC signal transduction system and promotes the intracellular cholesterol efflux from cells.