Tissue transglutaminase (TG2) acting as G protein protects hepatocytes against Fas-mediated cell death in mice.

Tissue transglutaminase (TG2) is a protein cross-linking enzyme known to be expressed by hepatocytes and to be induced during the in vivo hepatic apoptosis program. TG2 is also a G protein that mediates intracellular signaling by the alpha-1b-adrenergic receptor (AR) in liver cells. Fas/Fas ligand interaction plays a crucial role in various liver diseases, and administration of agonistic anti-Fas antibodies to mice causes both disseminated endothelial cell apoptosis and fulminant hepatic failure. Here we report that an intraperitoneal dose of anti-Fas antibodies, which is sublethal for wild-type mice, kills all the TG2 knock-out mice within 20 hours. Although TG2-/- thymocytes exposed to anti-Fas antibodies die at the same rate as wild-type mice, TG2-/- hepatocytes show increased sensitivity toward anti-Fas treatment both in vivo and in vitro, with no change in their cell surface expression of Fas, levels of FLIP(L) (FLICE-inhibitory protein), or the rate of I-kappaBalpha degradation, but a decrease in the Bcl-xL expression. We provide evidence that this is the consequence of the impaired AR signaling that normally regulates the levels of Bcl-xL in the liver. In conclusion, our data suggest the involvement of adrenergic signaling pathways in the hepatic regeneration program, in which Fas ligand-induced hepatocyte proliferation with a simultaneous inhibition of the Fas-death pathway plays a determinant role.

Helsinki 5.7.1924

Kirje

G-1 Appeal Activity in the Public Assistance Programs, August 2007

G-1 - Appeal Activity in the Public Assistance Programs - August 2007

G-1 Appeal Activity in the Public Assistance Programs, September 2007

G-1 - Appeal Activity in the Public Assistance Programs - September 2007

Un texte ethnographique inédit du XVIIIe siècle / par M. G. Marcel

Comprend : Les langues de Costa-Rica et les idiomes apparentés

Novas espécies e notas sinonímicas em Xystochroma Schmidt, 1924 (Coleoptera, Cerambycidae, Callichromatini)

Novas sinonímias propostas: X. neglectum (Gounelle, 1911) = Callichroma (Xystochroma) equestriforme Schmidt, 1924 syn. nov.; X. gracilipes (Bates, 1879) = Callichroma (Xystochroma) planipenne Schmidt, 1924 syn. nov. = Callichroma (Xystochroma) cuprisuturatum Zajciw, 1965 syn. nov. Novas espécies descritas do Brasil: X. femoratum sp. nov. (Minas Gerais e Rio Grande do Sul); X. echinatum sp. nov. (Rio de Janeiro e São Paulo); da Venezuela: X. incomptum sp. nov. (Amazonas). Chave para identificação das espécies de Xystochroma é fornecida.

G-1 Appeal Activity in the Public Assistance Programs, July 2007

G-1 - Appeal Activity in the Public Assistance Programs