Poss W B, Huecksteadt T P, Panus P C, Freeman B A, Hoidal J R
Department of Pediatrics, University of Utah School of Medicine, Salt Lake City 84132, USA.
Am J Physiol. 1996 Jun;270(6 Pt 1):L941-6. doi: 10.1152/ajplung.1996.270.6.L941.
The present study determined the effect of hypoxia on xanthine dehydrogenase (XDH) and xanthine oxidase (XO) activity and gene and protein expression in cultured bovine aortic endothelial cells (BAEC). BAEC were exposed to hypoxia (3% O2) or anoxia (0% O2) for 24 or 48 h and to 24 h of hypoxia followed by 24 h of reoxygenation. Hypoxia- and anoxia-exposed BAEC demonstrated a greater than twofold increase in XDH/XO activity at 24 and 48 h compared with timed controls. Hypoxic cells that were subsequently reoxygenated in 21% O2 also demonstrated a similar increase in XDH/XO activity vs. timed controls. No differences were seen in mRNA levels at any time point. Similarly, no difference was noted in XDH/XO protein expression after hypoxic exposure, as determined by Western blot analysis. The increase in XDH/XO activity was not prevented by cyclohexamide, indicating that protein synthesis was not required. Thus the increased XDH/XO activity observed in response to hypoxia in the present study was due to posttranslational modulation of the enzyme.
本研究确定了缺氧对培养的牛主动脉内皮细胞（BAEC）中黄嘌呤脱氢酶（XDH）和黄嘌呤氧化酶（XO）活性以及基因和蛋白质表达的影响。将BAEC暴露于缺氧（3% O₂）或无氧（0% O₂）环境24或48小时，以及先暴露于缺氧24小时然后再复氧24小时。与定时对照相比，暴露于缺氧和无氧环境的BAEC在24和48小时时XDH/XO活性增加了两倍以上。随后在21% O₂中复氧的缺氧细胞与定时对照相比，XDH/XO活性也有类似增加。在任何时间点，mRNA水平均未观察到差异。同样，通过蛋白质印迹分析确定，缺氧暴露后XDH/XO蛋白质表达也未观察到差异。环己酰亚胺未能阻止XDH/XO活性的增加，表明不需要蛋白质合成。因此，本研究中观察到的缺氧诱导的XDH/XO活性增加是由于该酶的翻译后调节。
