title: Lipopolysaccharide stimulates Epac1-mediated Rap1/NF-kappaB pathway in Raw 264.7 murine macrophages.
abstract: Nuclear factor-kappa B (NF-kappaB) is regulated by various stimulants to show many physiological results. Lipopolysaccharide (LPS) activates NF-kappaB through toll-like receptor 4 (TLR4)-dependent signal transduction. LPS-treatment also produces cyclic AMP (cAMP) in Raw 264.7 murine macrophages. Two principal effector proteins for cAMP are protein kinase A (PKA) and cAMP-responsive guanine nucleotide exchange factor (Epac), a Rap GDP exchange factor. Here, we investigated whether NF-kappaB can be activated by cAMP production through Epac1-mediated Rap1 activation by using Epac-specific cAMP analogue, 8-(4-chloro-phenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (CPT). NF-kappaB activity was increased by the treatment with CPT but it was reduced by co-transfection with dominant negative of Rap1 (Rap1N17). In conclusion, NF-kappaB activation should be regulated through Epac1-mediated Rap1 stimulation for LPS-induced inflammatory responses in murine macrophages. It suggests that Epac1-mediated Rap1/NF-kappaB pathway could be helpful for interpretation on various cAMP-mediated physiological responses and it could be used as a target to control their pathological abnormalities.
authors.affiliation: Department of Bioscience and Biotechnology, Sejong University, Seoul 143-747, Republic of Korea. eunyimoon@sejong.ac.kr <eunyimoon@sejong.ac.kr>
authors.forename: Eun-Yi
authors.initials: EY
authors.lastname: Moon
authors.forename: Suhkneung
authors.initials: S
authors.lastname: Pyo
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D000242:Cyclic AMP; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D005822:Genetic Vectors; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D000242:Cyclic AMP; D020827:rap1 GTP-Binding Proteins