Jeng I, Klemm N
Neurochem Res. 1984 Sep;9(9):1193-210. doi: 10.1007/BF00973034.
We investigated the incorporation of radioactive precursors into cholesteryl ester in cultured glioblastoma cells. It was found that polar cholesterol derivatives and exogenous cholesterol contained in lipoprotein complexes greatly enhanced intracellular cholesteryl ester formation. The direct transfer of the acyl moiety from acyl-CoA to free cholesterol was demonstrated in broken cell preparations. Further evidence of the existence of the acyl-CoA:cholesterol acyltransferase (ACAT) in glioblastoma cells came from the conversion of radioactive cholesterol to cholesteryl ester by glial cell homogenates. The characteristics of the enzymic assay were studied in detail. This enzymic activity was greatly enhanced in homogenates prepared from 7-ketocholesterol-treated cells. Thus, cells more active in cholesterol esterification in cell-free preparations. The marked inhibition of intracellular cholesteryl ester formation in intact cells by progesterone is a strong argument for the exclusive role of ACAT in glioblastoma cells. Similar properties of cholesteryl ester biosynthesis have been observed in neuroblastoma cells and primary brain cell cultures. In conclusion, the same enzyme is involved in cholesteryl ester biosynthesis in all neural cells. Neural and nonneural cells share many fundamental characteristics of cholesteryl ester formation.
我们研究了放射性前体掺入培养的胶质母细胞瘤细胞中胆固醇酯的情况。结果发现，脂蛋白复合物中含有的极性胆固醇衍生物和外源性胆固醇能极大地增强细胞内胆固醇酯的形成。在破碎细胞制剂中证实了酰基部分从酰基辅酶A直接转移至游离胆固醇。胶质母细胞瘤细胞中存在酰基辅酶A：胆固醇酰基转移酶（ACAT）的进一步证据来自神经胶质细胞匀浆将放射性胆固醇转化为胆固醇酯。对酶促测定的特性进行了详细研究。在由7-酮胆固醇处理的细胞制备的匀浆中，这种酶活性大大增强。因此，在无细胞制剂中细胞在胆固醇酯化方面更具活性。孕酮对完整细胞内胆固醇酯形成的显著抑制有力地证明了ACAT在胶质母细胞瘤细胞中的独特作用。在神经母细胞瘤细胞和原代脑细胞培养物中也观察到了胆固醇酯生物合成的类似特性。总之，所有神经细胞中胆固醇酯生物合成涉及相同的酶。神经细胞和非神经细胞在胆固醇酯形成方面具有许多基本特征。
