NF-kappaB stimulates inducible nitric oxide synthase to protect mouse hepatocytes from TNF-alpha- and Fas-mediated apoptosis.

Hepatocyte apoptosis is induced by tumor necrosis factor alpha (TNF-alpha) and Fas ligand. Although nuclear factor-kappaB (NF-kappaB) activation protects hepatocytes from TNF-alpha-mediated apoptosis, the NF-kappaB responsive genes that protect hepatocytes are unknown. Our aim was to study the role of NF-kappaB activation and inducible nitric oxide synthases (iNOSs) in TNF-alpha- and Fas-mediated apoptosis in hepatocytes. Primary cultures of hepatocytes from wild-type and iNOS knockout mice were treated with TNF-alpha, the Fas agonistic antibody Jo2, a nitric oxide (NO) donor (S-nitroso-N-acetylpenicillamine), an NO inhibitor (N(G)-methyl-L-arginine acetate), and/or adenovirus-expressing NF-kappaB inhibitors. The IkappaB superrepressor and a dominant-negative form of IkappaB kinase beta (IKKbeta) inhibited NF-kappaB binding activity by TNF-alpha or Jo2 and sensitized hepatocytes to TNF-alpha- and Jo2-mediated apoptosis. TNF-alpha and Jo2 induced iNOS messenger RNA and protein levels through the induction of NF-kappaB. S-nitroso-N-acetylpenicillamine inhibited Bid cleavage, the mitochondrial permeability transition, cytochrome c release, and caspase-8 and -3 activity, and reduced TNF-alpha- and Fas-mediated death in hepatocytes expressing IkappaB superrepressor. N(G)-methyl-L-arginine acetate partially sensitized hepatocytes to TNF-alpha- and Fas-mediated cell killing. TNF-alpha alone or Jo2 alone induced moderate cell death in hepatocytes from iNOS(-)/(-) mice. NO protects hepatocytes from TNF-alpha- and Fas-mediated apoptosis. Endogenous iNOS, which is activated by NF-kappaB via IKKbeta, provides partial protection from apoptosis.

被引量：51 发表：2001

Organization of intestinal pacemakers.

被引量：1 发表：2001

Colorectal cancer: not an equal opportunity cancer.

被引量：- 发表：2001

A mutation of the Wilson disease protein, ATP7B, is degraded in the proteasomes and forms protein aggregates.

BACKGROUND & AIMS:Wilson disease is a genetic disorder characterized by the accumulation of copper in the body as a result of a defect of copper excretion from hepatocytes. The intracellular localization of the Wilson disease gene product, ATP7B, was recently identified as the late endosomes. Various mutations have been documented in patients with Wilson disease. The clinical manifestations vary greatly among the patients; however, there is little information on the genotype-phenotype correlation. METHODS:We investigated the distribution of a common ATP7B mutant His1069Gln and a mutant Asp1270Ser by expressing the mutants tagged with green fluorescent protein in Huh7 and HEK293 cells. Intracellular organelles were visualized by fluorescence microscopy. RESULTS:Although the wild-type ATP7B and Asp1270Ser mutant localized in the late endosomes, His1069Gln mutant did not locate in the late endosomes and was degraded by the proteasomes in the cytoplasm. Furthermore, His1069Gln formed aggresomes composed of the degradates and intermediate filaments at the microtubule-organizing center. These aggresomes were similar to Mallory bodies on electron microscopy. CONCLUSIONS:The different protein properties of ATP7B mutants may explain the variety of clinical spectrums in patients with Wilson disease.

被引量：13 发表：2001

Prevalence of high-grade dysplasia and cancer in the anal canal in human papillomavirus-infected individuals.

BACKGROUND & AIMS:The incidence of anal cancer is higher in patients with anal canal condyloma, a sexually transmitted disease, than in the general population. We determined the prevalence of anal dysplasia and cancer in patients with anal canal condyloma with respect to human immunodeficiency virus (HIV) status, immunity status, and human papillomavirus types. METHODS:In 174 consecutive patients (114 HIV positive, 60 HIV negative) with anal canal condyloma, lesions were cured, and the patients were then followed up prospectively. Langerhans cells (LCs) in normal anal mucosa were quantified, and viruses (Epstein-Barr virus, cytomegalovirus, human simplex virus 1, and various human papillomavirus [HPV] types) were characterized on inclusion. During follow-up (median 26 months), relapsed condylomas were resected and examined histologically. HIV load and CD4 T-lymphocyte counts in serum were determined at each visit. RESULTS:Several factors differed significantly between HIV-positive and HIV-negative patients: LCs/mm anal tissue (15 vs. 30), oncogenic HPV (27% vs. 13%), other current anal infections (44% vs. 0%), and sex ratio (93% vs. 73% male). During follow-up, condylomas relapsed in 75% of the HIV-positive patients, with 19 high-grade dysplasias (HGDs) and 1 invasive carcinoma, but in only 6% of HIV-negative patients, with 1 HGD. Male sex, HIV positivity, and <15 LCs/mm tissue were independent risk factors for condyloma relapse. HIV positivity, HGD before inclusion, and condyloma relapse were independent risk factors for HGD and cancer. Serum HIV load was associated with relapse, whereas CD4 T-lymphocyte counts were not. CONCLUSIONS:The prevalence of HGD and carcinoma is higher in HIV-positive than in HIV-negative patients, probably because of HPV activity. HIV-positive patients with high serum HIV load and/or a history of anal dysplasia should be examined by anoscopy, and condylomas should be analyzed histologically.

被引量：12 发表：2001