Argininosuccinate synthetase: Localization in astrocytes and role in the production of glial nitric oxide

✍ Scribed by Andreas Schmidlin; and Heinrich Wiesinger

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 291 KB
• Volume: 24
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/(sici)1098-1136(199812)24:4<428::aid-glia8>3.0.co;2-1

✦ Synopsis

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-␥, 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.