Luis Albasanz José, Fernandez Mercedes, Martín Mairena
Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Universidad de Castilla-La Mancha, Avda Camilo José Cela, 10, 13071 Ciudad Real, Spain.
Brain Res Mol Brain Res. 2002 Feb 28;99(1):54-66. doi: 10.1016/s0169-328x(02)00103-1.
C6 glioma cells were treated for hours with 100 microM L-glutamate, quisqualate or trans-ACPD. In all cases, phospholipase C-coupled metabotropic glutamate receptors (mGluRs) present in these cells are down-regulated after this agonist treatment. Cell surface metabotropic glutamate receptor density was minimum at 6 h of agonist treatment and reached near control values after 30 h of treatment. This recovery was associated with a progressive increase in mGluR1 and mGluR1a mRNA level between 6 and 24 h and was not due to agonist removal. Specific L-[3H]glutamate or 3Htrans-ACPD binding decrease detected in C6 cells after 6 h of 100 microM L-glutamate treatment was associated with a remarkable increase of specific L-[3H]glutamate binding detected in clathrin-coated vesicles isolated from these treated cells. Moreover, this decrease was blocked in the presence of 0.5 M sucrose or 1 microM phenylarsine oxide, suggesting that desensitization and down-regulation of mGluR can be due to an endocytosis process through clathrin-coated pits and vesicles.
用100微摩尔/升的L-谷氨酸、quisqualate或反式-ACPD处理C6胶质瘤细胞数小时。在所有情况下，这些细胞中存在的与磷脂酶C偶联的代谢型谷氨酸受体（mGluRs）在这种激动剂处理后下调。激动剂处理6小时时细胞表面代谢型谷氨酸受体密度最低，处理30小时后接近对照值。这种恢复与6至24小时之间mGluR1和mGluR1a mRNA水平的逐渐增加有关，且不是由于激动剂的去除。在100微摩尔/升L-谷氨酸处理6小时后，C6细胞中检测到的特异性L-[3H]谷氨酸或3H反式-ACPD结合减少，与从这些处理过的细胞中分离出的网格蛋白包被小泡中检测到的特异性L-[3H]谷氨酸结合显著增加有关。此外，在存在0.5 M蔗糖或1微摩尔/升氧化苯胂的情况下，这种减少被阻断，这表明mGluR的脱敏和下调可能是由于通过网格蛋白包被凹陷和小泡的内吞作用过程。
