title: NF-κB plays an important role in indoxyl sulfate-induced cellular senescence, fibrotic gene expression, and inhibition of proliferation in proximal tubular cells.
abstract: We previously demonstrated that indoxyl sulfate induces senescence and dysfunction of proximal tubular cells by activating p53 expression. However, little is known about the role of nuclear factor (NF)-κB in these processes. The present study examines whether activation (phosphorylation) of NF-κB by indoxyl sulfate promotes senescence and dysfunction in human proximal tubular cells (HK-2 cells). Indoxyl sulfate induced phosphorylation of NF-κB p65 on Ser-276, which was suppressed by N-acetylcysteine, an antioxidant. Furthermore, indoxyl sulfate induced NF-κB p65 expression. Inhibitors of NF-κB (pyrrolidine dithiocarbamate and isohelenin) and NF-κB p65 small interfering RNA (siRNA) suppressed indoxyl sulfate-induced senescence-associated β-galactosidase activity and expression of p53, transforming growth factor (TGF)-β1, and α-smoothe muscle actin (SMA). The induction of p53 expression and p53 promoter activity by indoxyl sulfate were inhibited by pifithrin-α, p-nitro, an inhibitor of p53, whereas p53-transfected cells showed enhanced p53 promoter activity. NF-κB inhibitors suppressed indoxyl sulfate-induced p21 expression, whereas NF-κB p65 siRNA enhanced its expression. NF-κB inhibitors partially alleviated indoxyl sulfate-induced inhibition of cellular proliferation. NF-κB p65 siRNA-transfected cells showed less proliferation in the presence of indoxyl sulfate than control cells. Phosphorylated NF-κB p65 was expressed and colocalized with p53, p21, β-galactosidase, TGF-β1, and α-SMA in the kidneys of chronic renal failure (CRF) rats. AST-120, which reduces serum indoxyl sulfate level, suppressed their expression in the CRF rat kidneys. Taken together, NF-κB plays an important role in indoxyl sulfate-induced cellular senescence, fibrotic gene expression, and inhibition of proliferation in proximal tubular cells. More notably, indoxyl sulfate accelerates proximal tubular cell senescence with progression of CRF through reactive oxygen species-NF-κB-p53 pathway.
authors.affiliation: Department of Advanced Medicine for Uremia, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Japan.
authors.forename: Hidehisa
authors.initials: H
authors.lastname: Shimizu
authors.forename: Dilinaer
authors.initials: D
authors.lastname: Bolati
authors.forename: Ayinuer
authors.initials: A
authors.lastname: Adijiang
authors.forename: Gulinuer
authors.initials: G
authors.lastname: Muteliefu
authors.forename: Atsushi
authors.initials: A
authors.lastname: Enomoto
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Nishijima
authors.forename: Minori
authors.initials: M
authors.lastname: Dateki
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Niwa
mesh_terms: D000199:Actins / Q000378:metabolism; D058186:Acute Kidney Injury / Q000188:drug therapy / Q000378:metabolism; D000818:Animals; D052160:Benzothiazoles / Q000494:pharmacology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D006801:Humans; D007200:Indican / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000187:drug effects; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011759:Pyrrolidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012717:Sesquiterpenes / Q000494:pharmacology; D013859:Thiocarbamates / Q000494:pharmacology; D014050:Toluene / Q000031:analogs & derivatives / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D052160:Benzothiazoles; C493956:CDKN1A protein, human; C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016328:NF-kappa B; D011759:Pyrrolidines; D034741:RNA, Small Interfering; D012717:Sesquiterpenes; D013859:Thiocarbamates; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53; C103906:isohelenin; C020972:pyrrolidine dithiocarbamic acid; D014050:Toluene; C121565:pifithrin; D001616:beta-Galactosidase; D007200:Indican