Schmidlin A, Wiesinger H
Physiologisch-Chemisches Institut der Universität, Tübingen, Germany.
Glia. 1998 Dec;24(4):428-36.
An antiserum raised against the peptide representing the partial sequence 196-222 of mouse liver argininosuccinate synthetase (ASS) was used to detect and localize the enzyme in cells of neural primary cultures. No ASS immunoreactivity was detected by Western blotting in homogenates of mouse pure astroglial cultures and rat astroglia-rich cultures. However, when the cultures had been treated with bacterial lipopolysaccharide, interferon-gamma, or a combination of both, ASS immunoreactivity was disclosed. Immunocytochemical examination of rat astroglia-rich cultures revealed a colocalization of ASS with the astroglial marker glial fibrillary acidic protein (GFAP) in many cells. However, there were some GFAP-positive cells showing no specific staining for ASS, and vice versa. Colocalization of ASS with the inducible isoform of nitric oxide synthase in the same cell was shown only occasionally; nitric oxide synthase was predominantly expressed in microglial cells. In rat neuron-rich primary cultures astroglial cells as well as neurons expressed ASS. Cells of mouse pure astroglial cultures were able to synthesize arginine and, consequently, nitric oxide from citrulline, but not from ornithine. The findings demonstrate that ASS is expressed in astroglial cells under conditions that stimulate long-lasting production of nitric oxide; a functional role of this enzyme in the latter process is implicated.
用针对代表小鼠肝脏精氨琥珀酸合成酶（ASS）196 - 222部分序列的肽段制备的抗血清，来检测和定位神经原代培养细胞中的该酶。在小鼠纯星形胶质细胞培养物和大鼠富含星形胶质细胞的培养物的匀浆中，通过蛋白质免疫印迹法未检测到ASS免疫反应性。然而，当培养物用细菌脂多糖、γ干扰素或两者组合处理后，ASS免疫反应性被揭示出来。对大鼠富含星形胶质细胞的培养物进行免疫细胞化学检查发现，在许多细胞中ASS与星形胶质细胞标志物胶质纤维酸性蛋白（GFAP）共定位。然而，有一些GFAP阳性细胞对ASS无特异性染色，反之亦然。ASS与一氧化氮合酶的诱导型同工型在同一细胞中的共定位仅偶尔出现；一氧化氮合酶主要在小胶质细胞中表达。在大鼠富含神经元的原代培养物中，星形胶质细胞和神经元都表达ASS。小鼠纯星形胶质细胞培养物的细胞能够从瓜氨酸合成精氨酸，进而合成一氧化氮，但不能从鸟氨酸合成。这些发现表明，在刺激一氧化氮长期产生的条件下，ASS在星形胶质细胞中表达；该酶在后者过程中的功能作用也被暗示。
