Novel changes in NF-{kappa}B activity during progression and regression phases of hyperplasia: role of MEK, ERK, and p38.
Utilizing the Citrobacter rodentium-induced transmissible murine colonic hyperplasia (TMCH) model, we measured hyperplasia and NF-κB activation during progression (days 6 and 12 post-infection) and regression (days 20-34 post-infection) phases of TMCH. NF-κB activity increased at progression in conjunction with bacterial attachment and translocation to the colonic crypts and decreased 40% by day 20. NF-κB activity at days 27 and 34, however, remained 2-3-fold higher than uninfected control. Expression of the downstream target gene CXCL-1/KC in the crypts correlated with NF-κB activation kinetics. Phosphorylation of cellular IκBα kinase (IKK)α/β (Ser(176/180)) was elevated during progression and regression of TMCH. Phosphorylation (Ser(32/36)) and degradation of IκBα, however, contributed to NF-κB activation only from days 6 to 20 but not at later time points. Phosphorylation of MEK1/2 (Ser(217/221)), ERK1/2 (Thr(202)/Tyr(204)), and p38 (Thr(180)/Tyr(182)) paralleled IKKα/β kinetics at days 6 and 12 without declining with regressing hyperplasia. siRNAs to MEK, ERK, and p38 significantly blocked NF-κB activity in vitro, whereas MEK1/2-inhibitor (PD98059) also blocked increases in MEK1/2, ERK1/2, and IKKα/β thereby inhibiting NF-κB activity in vivo. Cellular and nuclear levels of Ser(536)-phosphorylated (p65(536)) and Lys(310)-acetylated p65 subunit accompanied functional NF-κB activation during TMCH. RSK-1 phosphorylation at Thr(359)/Ser(363) in cellular/nuclear extracts and co-immunoprecipitation with cellular p65-NF-κB overlapped with p65(536) kinetics. Dietary pectin (6%) blocked NF-κB activity by blocking increases in p65 abundance and nuclear translocation thereby down-regulating CXCL-1/KC expression in the crypts. Thus, NF-κB activation persisted despite the lack of bacterial attachment to colonic mucosa beyond peak hyperplasia. The MEK/ERK/p38 pathway therefore seems to modulate sustained activation of NF-κB in colonic crypts in response to C. rodentium infection.
Chandrakesan
Parthasarathy
P
From the Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Ahmed
Ishfaq
I
From the Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
Anwar
Tariq
T
Centre for Molecular Biosciences, University of Ulster, BT52 1SA Coleraine, United Kingdom.
Wang
Yu
Y
Departments of Internal Medicine, Galveston, Texas 77555.
Sarkar
Shubhashish
S
Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555.
Singh
Pomila
P
Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555.
Peleg
Sara
S
Department of Endocrine Neoplasia and Hormone Disorder Research, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.
Umar
Shahid
S
From the Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104. Electronic address: Shahid-Umar@ouhsc.edu.
D000818:Animals; D054360:Chemokine CXCL1 / Q000096:biosynthesis / Q000235:genetics; D044082:Citrobacter rodentium; D003106:Colon / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D003108:Colonic Diseases / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D004756:Enterobacteriaceae Infections / Q000235:genetics / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006965:Hyperplasia / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D054360:Chemokine CXCL1; C475895:Cxcl1 protein, mouse; D005419:Flavonoids; D020672:I-kappa B Proteins; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D000072000:NF-KappaB Inhibitor alpha; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C512964:Rps6ka1 protein, mouse; C496559:CHUK protein, human; D051550:I-kappa B Kinase; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482127:Map2k1 protein, mouse; C482129:Map2k2 protein, mouse; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one