Kivatinitz S C, Grabois V R, Quiroga S
Departamento de Química Biológica-CIQUIBIC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
J Neurochem. 1995 Aug;65(2):775-81. doi: 10.1046/j.1471-4159.1995.65020775.x.
We have previously described a thermostable inhibitor of the UDP-N-acetylgalactosamine:GM3,N-acetylgalactosaminyltransferase (GM2 synthase) purified from chicken blood serum. Some properties of the GM2 synthase inhibitory preparation (IP) resemble those of high-density lipoprotein (HDL), i.e., both have a MW of 200,000 in native conditions and are resistant to denaturation by heat. These and other facts prompted us to test the possibility that lipoproteins regulate ganglioside biosynthesis in the CNS. For this purpose, serum lipoprotein fractions were isolated from chicken serum by flotation and were assayed as inhibitors of GM2 synthase activity and of neuron differentiation in culture. HDL (in contrast to fractions containing very low-density or low-density lipoprotein) inhibited GM2 synthase with the same specific activity as IP and inhibited neuron cell differentiation in culture in a similar way. Furthermore, these two preparations also share several other characteristics; i.e., both have the same cholesterol content, the same floating behavior on KBr gradients, and the same polypeptide pattern as detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and staining with Coomassie Blue, or after western blot and revealing with an antibody prepared against IP, which is able to diminish the inhibitory effect of this preparation. The results described indicate identity between HDL and IP and suggest that HDL (particularly apolipoprotein A) could play an important role on ganglioside biosynthesis modulation during CNS development. The antineuritogenic effect of HDL described in this study could be of physiological relevance during CNS development and response to injury.
我们之前曾描述过一种从鸡血清中纯化得到的UDP-N-乙酰半乳糖胺：GM3，N-乙酰半乳糖胺基转移酶（GM2合酶）的热稳定抑制剂。GM2合酶抑制制剂（IP）的一些特性与高密度脂蛋白（HDL）相似，即在天然条件下两者的分子量均为200,000，且都耐热变性。这些及其他事实促使我们去测试脂蛋白调节中枢神经系统中神经节苷脂生物合成的可能性。为此，通过浮选从鸡血清中分离出血清脂蛋白组分，并将其作为GM2合酶活性及培养中神经元分化的抑制剂进行检测。HDL（与含有极低密度或低密度脂蛋白的组分不同）抑制GM2合酶的比活性与IP相同，并以类似方式抑制培养中的神经元细胞分化。此外，这两种制剂还具有其他一些共同特征；即两者具有相同的胆固醇含量、在KBr梯度上相同的漂浮行为，以及通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和考马斯亮蓝染色，或在蛋白质免疫印迹后用针对IP制备的抗体进行显色检测时呈现相同的多肽图谱，该抗体能够减弱该制剂的抑制作用。所述结果表明HDL与IP相同，并提示HDL（尤其是载脂蛋白A）可能在中枢神经系统发育过程中对神经节苷脂生物合成的调节中发挥重要作用。本研究中描述的HDL的抗神经原性作用在中枢神经系统发育及对损伤的反应过程中可能具有生理相关性。
