Olmos Gemma, Conde Isabel, Arenas Isabel, Del Peso Luis, Castellanos Carmen, Landazuri Manuel O, Lucio-Cazana Javier
Departamento de Fisiología, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, 28871 Madrid, Spain.
Cell Signal. 2007 Oct;19(10):2098-105. doi: 10.1016/j.cellsig.2007.06.004. Epub 2007 Jun 21.
15-deoxy-Delta(12,14)-prostaglandin-J(2) (15d-PGJ(2)) is a peroxisome-activated proliferator receptor-gamma (PPARgamma) agonist which contains an alpha,beta-unsaturated electrophilic ketone involved in nucleophilic addition reactions to thiols. Here we studied its effect on hypoxia-inducible factor-1alpha (HIF-1alpha) in human proximal tubular cells HK-2. 15d-PGJ(2) induced stabilization of HIF-1alpha protein, without affecting HIF-1alpha mRNA levels or proteasome activity, leading to its nuclear accumulation and activation of HIF-induced transcription. Accumulation of HIF-1alpha was unaffected by selective PPARgamma blockade nor mimicked by the PPARgamma agonists ciglitazone and 9,10-dihydro-15d-PGJ(2). N-acetylcysteine, reduced glutathione (GSH) or dithiothreitol (i.e. agents that act as thiol reducing agents and/or increase the GSH content), but not reactive oxygen species (ROS) scavengers, prevented 15d-PGJ(2)-induced HIF-1alpha accumulation whereas the inhibitor of GSH synthesis buthionine sulfoximine cooperated with 15d-PGJ(2) to accumulate HIF-1alpha. Finally, HIF-1alpha expression was increased by the electrophilic alpha,beta-unsaturated compounds acrolein and PGA(2), but not by 9,10-dihydro-15d-PGJ(2), which lacks the electrophilic cyclopentenone moiety. Taken together, these results point out to a new mechanism to increase pharmacologically the cell levels of HIF-1alpha through the electrophilic reaction of alpha,beta-unsaturated ketones with thiol groups.
15-脱氧-Δ(12,14)-前列腺素-J₂（15d-PGJ₂）是一种过氧化物酶体激活增殖受体-γ（PPARγ）激动剂，它含有一个α,β-不饱和亲电酮，可参与与硫醇的亲核加成反应。在此，我们研究了其对人近端肾小管细胞HK-2中缺氧诱导因子-1α（HIF-1α）的影响。15d-PGJ₂诱导HIF-1α蛋白的稳定，而不影响HIF-1α mRNA水平或蛋白酶体活性，导致其核内积累并激活HIF诱导的转录。HIF-1α的积累不受选择性PPARγ阻断的影响，也未被PPARγ激动剂吡格列酮和9,10-二氢-15d-PGJ₂模拟。N-乙酰半胱氨酸、还原型谷胱甘肽（GSH）或二硫苏糖醇（即作为硫醇还原剂和/或增加GSH含量的试剂），而非活性氧（ROS）清除剂，可阻止15d-PGJ₂诱导的HIF-1α积累，而GSH合成抑制剂丁硫氨酸亚砜胺则与15d-PGJ₂协同作用使HIF-1α积累。最后，亲电α,β-不饱和化合物丙烯醛和PGA₂可增加HIF-1α的表达，但缺乏亲电环戊烯酮部分的9,10-二氢-15d-PGJ₂则不能。综上所述，这些结果指出了一种通过α,β-不饱和酮与硫醇基团的亲电反应在药理学上增加细胞内HIF-1α水平的新机制。
