Differential roles of PKA and Epac on the production of cytokines in the endotoxin-stimulated primary cultured microglia.
To further understand the anti-inflammatory effect of adenosine cyclic 3',5'-monophosphate (cAMP), we examined the effect of protein kinase A (PKA) and cAMP-responsive guanine nucleotide exchange factor (Epac) on the transcription and production of cytokines and on the activity of mitogen-activated protein kinases (MAPK) p38 and glycogen synthase kinase-3β (GSK-3β) in endotoxin-treated rat primary cultured microglia. The PKA specific agonist N6-benzoyladenosine-3,5-cAMP (6-Bnz-cAMP) not only inhibited the transcription and production of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) but also enhanced the transcription and expression of IL-10, while the Epac selective analog 8-(4-chlorophenylthio)-2-O-methyladenosine-3,5-cAMP (8-pCPT-2'-O-Me-cAMP) merely repressed the TNF-α expression. Western blots assays indicated that 6-Bnz-cAMP significantly inhibited lipopolysaccharide-induced activation of both p38 and GSK-3β in a dose-dependent manner; in contrast, 8-pCPT-2'-O-Me-cAMP only slightly repressed GSK-3β activity at large doses. Pretreatment with H-89, a specific PKA antagonist, could completely reverse the effect of 6-Bnz-cAMP on cytokines expressions and kinases activities but had no effect on the performance of 8-pCPT-2'-O-Me-cAMP. Our findings indicate that PKA and Epac exert differential effect on the expression of inflammatory cytokines such as TNF-α, IL-1β, and IL-10, possibly owing to the different effects on the downstream effectors, MAPK p38, and GSK-3β.
Liu
Jian
J
Department of Anesthesiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, 197 Ruijin Er Road, Shanghai, 200025, People's Republic of China.
Zhao
Xin
X
Cao
Jianping
J
Xue
Qingsheng
Q
Feng
Xiaomei
X
Liu
Xuesheng
X
Zhang
Fujun
F
Yu
Buwei
B
D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004731:Endotoxins / Q000494:pharmacology*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; D004731:Endotoxins; D020662:Guanine Nucleotide Exchange Factors; D053583:Interleukin-1beta; C526973:Rapgef3 protein, rat; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases