Yun Bogeon, Lee HeeJung, Jayaraja Sabarirajan, Suram Saritha, Murphy Robert C, Leslie Christina C
From the Department of Pediatrics, National Jewish Health, Denver, Colorado 80206 and.
the Departments of Pharmacology and.
J Biol Chem. 2016 Mar 25;291(13):7070-86. doi: 10.1074/jbc.M116.714873. Epub 2016 Feb 3.
In Candida albicans-infected resident peritoneal macrophages, activation of group IVA cytosolic phospholipase A2(cPLA2α) by calcium- and mitogen-activated protein kinases triggers the rapid production of prostaglandins I2 and E2 through cyclooxygenase (COX)-1 and regulates gene expression by increasing cAMP. InC. albicans-infected cPLA2α(-/-)or COX-1(-/-)macrophages, expression ofI l10,Nr4a2, and Ptgs2 was lower, and expression ofTnfα was higher, than in wild type macrophages. Expression was reconstituted with 8-bromo-cAMP, the PKA activator 6-benzoyl-cAMP, and agonists for prostaglandin receptors IP, EP2, and EP4 in infected but not uninfected cPLA2α(-/-)or COX-1(-/-)macrophages. InC. albicans-infected cPLA2α(+/+)macrophages, COX-2 expression was blocked by IP, EP2, and EP4 receptor antagonists, indicating a role for both prostaglandin I2 and E2 Activation of ERKs and p38, but not JNKs, by C. albicansacted synergistically with prostaglandins to induce expression of Il10,Nr4a2, and Ptgs2. Tnfα expression required activation of ERKs and p38 but was suppressed by cAMP. Results using cAMP analogues that activate PKA or Epacs suggested that cAMP regulates gene expression through PKA. However, phosphorylation of cAMP-response element-binding protein (CREB), the cAMP-regulated transcription factor involved inIl10,Nr4a2,Ptgs2, andTnfα expression, was not mediated by cAMP/PKA because it was similar inC. albicans-infected wild type and cPLA2α(-/-)or COX-1(-/-)macrophages. CREB phosphorylation was blocked by p38 inhibitors and induced by the p38 activator anisomycin but not by the PKA activator 6-benzoyl-cAMP. Therefore, MAPK activation inC. albicans-infected macrophages plays a dual role by promoting the cPLA2α/prostaglandin/cAMP/PKA pathway and CREB phosphorylation that coordinately regulate immediate early gene expression.
在白色念珠菌感染的驻留腹膜巨噬细胞中,钙和丝裂原激活的蛋白激酶对IVA组胞质磷脂酶A2(cPLA2α)的激活,通过环氧化酶(COX)-1触发前列腺素I2和E2的快速产生,并通过增加cAMP来调节基因表达。在白色念珠菌感染的cPLA2α(-/-)或COX-1(-/-)巨噬细胞中,与野生型巨噬细胞相比,Il10、Nr4a2和Ptgs2的表达较低,而Tnfα的表达较高。在感染但未感染的cPLA2α(-/-)或COX-1(-/-)巨噬细胞中,用8-溴-cAMP、PKA激活剂6-苯甲酰-cAMP以及前列腺素受体IP、EP2和EP4的激动剂可使表达恢复。在白色念珠菌感染的cPLA2α(+/+)巨噬细胞中,COX-2的表达被IP、EP2和EP4受体拮抗剂阻断,表明前列腺素I2和E2均起作用。白色念珠菌对细胞外调节蛋白激酶(ERK)和p38的激活,但不包括应激活化蛋白激酶(JNK),与前列腺素协同诱导Il10、Nr4a2和Ptgs2的表达。Tnfα的表达需要ERK和p38的激活,但被cAMP抑制。使用激活PKA或交换蛋白直接激活剂(Epac)的cAMP类似物的结果表明,cAMP通过PKA调节基因表达。然而,参与Il10、Nr4a2、Ptgs2和Tnfα表达的cAMP调节转录因子——cAMP反应元件结合蛋白(CREB)的磷酸化,并非由cAMP/PKA介导,因为在白色念珠菌感染的野生型和cPLA2α(-/-)或COX-1(-/-)巨噬细胞中,其磷酸化情况相似。CREB磷酸化被p38抑制剂阻断,并被p38激活剂茴香霉素诱导,但未被PKA激活剂6-苯甲酰-cAMP诱导。因此,白色念珠菌感染的巨噬细胞中丝裂原活化蛋白激酶(MAPK)的激活通过促进cPLA2α/前列腺素/cAMP/PKA途径和CREB磷酸化发挥双重作用,从而协调调节立即早期基因表达。