REGULATION OF ZINC PROTEINS AND CELLULAR ZINC HOMEOSTASIS

共面多氯联苯的毒性表现被认为是由芳香烃受体介导的。然而，共面多氯联苯对蛋白表达的抑制作用尚不清楚。我们在这里报告了共面多氯联苯处理对细胞质蛋白的抑制，并提出了毒性的新方面。雄性Wistar大鼠灌胃单药（25 mg/kg, ig）。自由喂养组和配对喂养组分别给予载虫治疗。第5天，制备肝细胞质溶胶。通过SDS-PAGE和二维RAGE （2D-PAGE）比较三组胞质蛋白。大鼠肝细胞内40-kDa和27-kDa蛋白表达水平明显受到pb - b处理的抑制。通过对其内部肽的氨基酸测序，鉴定其为醛缩酶B （Ald B）和醇脱氢酶（ADH） I类。27 kda蛋白也被鉴定为碳酸酐酶III （CA II）。小鼠肝细胞内Ald和ADH活性显著降低，分别为对照组的50%和60%左右。sD-PAGE后的免疫印迹显示，铅笔处理明显抑制了Ald B，而Ald A的变化很小。免疫印迹也证实了铅笔处理对ADH的减少。利用CAⅲ选择性抗体进行免疫印迹分析，证实了铅笔b对大鼠肝脏CAⅲ的显著抑制作用。Ald在糖酵解和糖异生途径中起重要作用。此外，ADH还催化磷酸三糖转化为甘油-3-磷酸。Ald B和ADH的抑制可能是ppb治疗引起的中间代谢紊乱的关键生化损害，并应被认为是导致消耗综合征的原因，而消耗综合征是有毒共面多氯联苯的严重毒性效应。CA III具有酪氨酸磷酸酶活性，因此，其抑制可以解释有毒共面多氯联苯对信号转导的影响。

Toxic manifestation of coplanar PCB is thought to be mediated by aromatic hydrocarbon (Ah)-receptor. However, the suppression of protein expression by coplanar PCBs is scarcely clarified. We report here the suppression of cytosolic proteins by a coplanar PCB-treatment and propose new aspects of the toxicity. Male Wistar rats were treated with PenCB (single 25 mg/kg, i. p.). Free- and pair-fed control groups were treated with vehicle. At the day 5, the liver cytosol was prepared. The cytosolic proteins were compared among three groups by SDS-PAGE and two-dimensional RAGE (2D-PAGE). Expression level of cytosolic 40-kDa and 27-kDa proteins in rat liver were markedly suppressed by PenCB-treatment. The 40-kDa proteins were identified as aldolase B (Ald B) and alcohol dehydrogenase (ADH) class I by amino acid sequencing of the internal peptides. The 27-kDa protein was also identified as carbonic anhydrase III (CA II). The liver cytosolic Ald and ADH activities were significantly reduced to about 50% and 60% of both control groups by PenCB-treatment. Immunoblotting after sD-PAGE demonstrated that Ald B was markedly suppressed by PenCB-treatment, while change in Ald A was slight. The reduction of ADH by PenCB-treatment was also verified by immunoblotting. The significant suppression of CA III by PenCB-treatment in rat liver was demonstrated by immunoblotting using CA III-selective antibody. Ald plays an important role in glycolytic and gluconeogenetic pathways. In addition, ADH catalyzes biotransformation of triose phosphate to glycerol-3-phosphate. Sippression of Ald B and ADH may be a key biochemical lesion for disordered intermediary metabolism occurring by PenCB-treatment and should be taken into an account as a cause of the wasting syndrom which is a severe toxic effect of toxic coplanar PCBs. CA III possesses tyrosine phosphatase activity, therefore, its suppression could account for the effects on signal transduction by toxic coplanar PCBs.