Fernández-Martínez Ana B, Lucio Cazaña Francisco J
Departamento de Biología de Sistemas, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
Departamento de Biología de Sistemas, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
Biochim Biophys Acta. 2014 Sep;1843(9):1997-2004. doi: 10.1016/j.bbamcr.2014.05.013. Epub 2014 Jun 2.
The pharmacological modulation of putative renoprotective factors hypoxia-inducible factor-1α (HIF-1α) and HIF-1α-regulated vascular endothelial growth factor-A (VEGF-A) in the kidney has therapeutic interest. In human renal proximal tubular HK2 cells, prostaglandin E2 (PGE2) up-regulates HIF-1α and VEGF-A through epidermal growth factor receptor (EGFR)-dependent up-regulation of retinoic acid receptor-β (RARβ). Here we studied the role of mitogen-activated protein kinases (MAPKs) ERK1/2 and p38 and their target kinase, mitogen- and stress activated kinase-1 (MSK1), in the signaling cascade. Treatment of HK2 cells with PGE2 resulted in increased phosphorylation of EGFR, the three studied kinases and the histone H3 (Ser10) at the RARβ gene promoter (the latter has been proposed as a molecular signature of the activated RARβ gene promoter). Prevention of the phosphorylation of EGFR, ERK1/2, p38 MAPK or MSK1 is by incubating, respectively, with AG1478, PD98059, SB203580 or H89 allowed to elucidate the precise phosphorylation order in the signaling cascade triggered by PGE2: first, EGFR; then, ERK1/2 and p38 MAPK and, finally, MSK1. Phosphorylation of MSK1 led to that of Ser10 in histone H3 and to activation of RARβ gene transcription (and the consequent increase in the expression of HIF-1α and VEGF-A), which was suppressed by H89 or by transfecting cells with a vector encoding for a dominant-negative mutant of MSK1. These results highlight the relevance of MSK1 in the up-regulation of RARβ by PGE2. They also may contribute to new therapeutic approaches based upon the pharmacological control of HIF-1α/VEGF-A in the proximal tubule through the modulation of the PGE2/EGFR/MAPK/MSK1/RARβ pathway.
对肾脏中假定的肾保护因子缺氧诱导因子-1α（HIF-1α）和HIF-1α调节的血管内皮生长因子-A（VEGF-A）进行药理学调节具有治疗意义。在人肾近端小管HK2细胞中，前列腺素E2（PGE2）通过表皮生长因子受体（EGFR）依赖性上调视黄酸受体-β（RARβ）来上调HIF-1α和VEGF-A。在此，我们研究了丝裂原活化蛋白激酶（MAPK）ERK1/2和p38及其靶激酶丝裂原和应激激活激酶-1（MSK1）在信号级联反应中的作用。用PGE2处理HK2细胞导致EGFR、三种研究的激酶以及RARβ基因启动子处的组蛋白H3（Ser10）磷酸化增加（后者被认为是活化的RARβ基因启动子的分子标志）。分别用AG1478、PD98059、SB203580或H89孵育可阻止EGFR、ERK1/2、p38 MAPK或MSK1的磷酸化，从而阐明PGE2触发的信号级联反应中的精确磷酸化顺序：首先是EGFR；然后是ERK1/2和p38 MAPK，最后是MSK1。MSK1的磷酸化导致组蛋白H3中Ser10的磷酸化以及RARβ基因转录的激活（以及随后HIF-1α和VEGF-A表达的增加），这被H89或用编码MSK1显性负突变体的载体转染细胞所抑制。这些结果突出了MSK1在PGE2上调RARβ中的相关性。它们也可能有助于基于通过调节PGE2/EGFR/MAPK/MSK1/RARβ途径对近端小管中HIF-1α/VEGF-A进行药理学控制的新治疗方法。
