title: TNF-α Modulation of Intestinal Tight Junction Permeability Is Mediated by NIK/IKK-α Axis Activation of the Canonical NF-κB Pathway.
abstract: Tumor necrosis factor (TNF)-α, a key mediator of intestinal inflammation, causes an increase in intestinal epithelial tight junction (TJ) permeability by activating myosin light chain kinase (MLCK; official name MYLK3) gene. However, the precise signaling cascades that mediate the TNF-α-induced activation of MLCK gene and increase in TJ permeability remain unclear. Our aims were to delineate the upstream signaling mechanisms that regulate the TNF-α modulation of intestinal TJ barrier function with the use of in vitro and in vivo intestinal epithelial model systems. TNF-α caused a rapid activation of both canonical and noncanonical NF-κB pathway. NF-κB-inducing kinase (NIK) and mitogen-activated protein kinase kinase-1 (MEKK-1) were activated in response to TNF-α. NIK mediated the TNF-α activation of inhibitory κB kinase (IKK)-α, and MEKK1 mediated the activation of IKK complex, including IKK-β. NIK/IKK-α axis regulated the activation of both NF-κB p50/p65 and RelB/p52 pathways. Surprisingly, the siRNA induced knockdown of NIK, but not MEKK-1, prevented the TNF-α activation of both NF-κB p50/p65 and RelB/p52 and the increase in intestinal TJ permeability. Moreover, NIK/IKK-α/NF-κB p50/p65 axis mediated the TNF-α-induced MLCK gene activation and the subsequent MLCK increase in intestinal TJ permeability. In conclusion, our data show that NIK/IKK-α/regulates the activation of NF-κB p50/p65 and plays an integral role in the TNF-α-induced activation of MLCK gene and increase in intestinal TJ permeability.
authors.affiliation: Department of Internal Medicine, University of New Mexico School of Medicine and Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico.
authors.forename: Rana
authors.initials: R
authors.lastname: Al-Sadi
authors.affiliation: Department of Internal Medicine, University of New Mexico School of Medicine and Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Guo
authors.affiliation: Department of Internal Medicine, University of New Mexico School of Medicine and Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Ye
authors.affiliation: Department of Internal Medicine, University of New Mexico School of Medicine and Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico.
authors.forename: Manmeet
authors.initials: M
authors.lastname: Rawat
authors.affiliation: Department of Internal Medicine, University of New Mexico School of Medicine and Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico. Electronic address: tma@salud.unm.edu.
authors.forename: Thomas Y
authors.initials: TY
authors.lastname: Ma
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002478:Cells, Cultured; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism*; D007421:Intestine, Small / Q000502:physiology; D048728:MAP Kinase Kinase Kinase 1 / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000502:physiology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000378:metabolism; D052003:NF-kappa B p52 Subunit / Q000378:metabolism; D010539:Permeability; D011401:Promoter Regions, Genetic / Q000502:physiology; D034741:RNA, Small Interfering / Q000378:metabolism; D019108:Tight Junctions / Q000502:physiology*; D051996:Transcription Factor RelA / Q000378:metabolism; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*
chemical_list: D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D052003:NF-kappa B p52 Subunit; D034741:RNA, Small Interfering; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D051550:I-kappa B Kinase; D009219:Myosin-Light-Chain Kinase; C524358:cardiac myosin light chain kinase, human; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human