Compound C induces the ramification of murine microglia in an AMPK-independent and small rhogtpase-dependent manner.
Microglial cells are the pivotal immune cells of the central nervous system. Adult microglia cells under physiological conditions are in a ramification state with extensively branched processes. Upon disease stimulation, they retract their processes and become activated. Induction of ramification is an attracting strategy to terminate the excessive activation of microglia. Here, we investigated the influence of compound C (CC) on microglial shape. Results showed that CC reversibly induced a ramification of murine microglia in both basal and inflammatory conditions. These pro-ramification effects were independent of adenosine 5'-monophosphate-activated protein kinase (AMPK) inhibition as both AMPKα1 and AMPKα2 silence failed to induce microglial ramification. The ramification state of microglia induced by CC was associated with a decrease in pro-inflammatory factors and an increase in brain-derived neurotrophic factors (BDNF) protein and phagocytic activity. Mechanistic studies confirmed that the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signal, extracellular signal-regulated kinase 1/2 (ERK1/2) or small RhoGTPase activation mediated the effect of CC on microglial shape change based on the following observations: (i) CC induced a significant activation of the small RhoGTPase Rac1 and Cdc42; (ii) CC promoted the phosphorylation of ERK1/2 and Akt; (iii) inhibition of Rac1, Cdc42, ERK1/2, or the PI3K-Akt signal abolished the effect of CC on microglial shape change. These signal mechanisms were also ascertained in primary microglia. Our results explore a potential agent that promotes microglial ramification, and provide an alternative explanation for the neuroprotective effects of CC in various disease models such as brain ischemia and subarachnoid hemorrhage.
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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Huang
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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Lu
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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Wang
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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Tong
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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Ling
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China.
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Jiang
Department of Anesthesiology, Affiliated Hospital of Nantong University, Jiangsu Province, #20 Xisi Road, Nantong, Jiangsu Province 226001, China. Electronic address: charliechao888888@163.com.
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Yang
Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China; Key Laboratory of Inflammation and Molecular Drug Target of Jiangsu Province, #19 Qixiu Road, Nantong, Jiangsu Province 226001, China. Electronic address: asicampa@aliyun.com.
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Zhang
D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D051379:Mice; D017628:Microglia / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D013997:Time Factors; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C535148:Mapk1 protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D055372:AMP-Activated Protein Kinases; D020741:rho GTP-Binding Proteins
AMPK; compound C; microglia; ramification