RESUMO
A zoonotic A/sw/H1avN1 1C.2.2 influenza virus infection was detected in a German child that presented with influenza-like illness, including high fever. There was a history of close contact with pigs 3 days before symptom onset. The child recovered within 3 days. No other transmissions were observed. Serological investigations of the virus isolate revealed cross-reactions with ferret antisera against influenza A(H1N1)pdm09 virus, indicating a closer antigenic relationship with A(H1N1)pdm09 than with the former seasonal H1N1 viruses.
Assuntos
Variação Antigênica/genética , Furões/virologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A Subtipo H1N1/genética , Influenza Humana/diagnóstico , Infecções por Orthomyxoviridae/diagnóstico , Doenças dos Suínos/transmissão , Zoonoses/virologia , Animais , Anticorpos Antivirais/sangue , Variação Antigênica/imunologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Humanos , Vírus da Influenza A Subtipo H1N1/classificação , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Influenza Humana/transmissão , Influenza Humana/virologia , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/veterinária , Infecções por Orthomyxoviridae/virologia , Reação em Cadeia da Polimerase , Análise de Sequência , Suínos , Doenças dos Suínos/virologia , Zoonoses/transmissãoRESUMO
Bak and Bax are critical apoptotic mediators that naturally localize to both mitochondria and the endoplasmic reticulum (ER). Although it is generally accepted that mitochondrial expression of Bak or Bax suffices for apoptosis initiated by BH3-only homologues, it is currently unclear whether their reticular counterparts may have a similar potential. In this study, we show that cells exclusively expressing Bak in endoplasmic membranes undergo cytochrome c mobilization and mitochondrial apoptosis in response to BimEL and Puma, even when these BH3-only molecules are also targeted to the ER. Surprisingly, calcium was necessary but not sufficient to drive the pathway, despite normal ER calcium levels. We provide evidence that calcium functions coordinately with the ER-stress surveillance machinery IRE1alpha/TRAF2 to transmit apoptotic signals from the reticulum to mitochondria. These results indicate that BH3-only mediators can rely on reticular Bak to activate an ER-to-mitochondria signalling route able to induce cytochrome c release and apoptosis independently of the canonical Bak,Bax-dependent mitochondrial gateway, thus revealing a new layer of complexity in apoptotic regulation.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose , Retículo Endoplasmático/metabolismo , Fibroblastos/citologia , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Animais , Apoptose/efeitos dos fármacos , Proteína 11 Semelhante a Bcl-2 , Cálcio/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Linhagem Celular , Citocromos b5/metabolismo , Citocromos c/metabolismo , Retículo Endoplasmático/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Proteínas Serina-Treonina Quinases/metabolismo , Transporte Proteico/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Fator 2 Associado a Receptor de TNF/metabolismoRESUMO
Bcl-2 family members Bak and Bax constitute a mitochondrial gateway for multiple death pathways. Both proteins are also present in the endoplasmic reticulum where they control apoptosis through the regulation of calcium levels. We show here that reticular Bak has the additional capacity of modulating the structure of this organelle. Coexpression of Bak and Bcl-X(L) provokes extensive swelling and vacuolization of reticular cisternae. A Bak version lacking the BH3 domain suffices to induce this phenotype, and reticular targeting of this mutant retains the activity. Expression of upstream BH3-only activators in similar conditions recapitulates ER swelling and vacuolization if ryanodine receptor calcium channel activity is inhibited. Experiments with Bak and Bax-deficient mouse embryonic fibroblasts show that endogenous Bak mediates the effect, whereas Bax is mainly irrelevant. These results reveal a previously unidentified role of Bak in regulating reticular conformation. Because this activity is absent in Bax, it constitutes one of the first examples of functional divergence between the two multidomain homologues.
