RESUMO
Rho GTPases regulate diverse cellular functions including adhesion, cytokinesis and motility, as well as the activity of the transcription factors NF-kappaB, serum response factor and C/EBP. alpha-Catulin, an alpha-catenin-related protein that shares structural similarities with cytoskeletal linker proteins, facilitates Rho signalling by serving as a scaffold for the Rho-specific guanine nucleotide exchange factor Lbc. We report here that alpha-catulin also interacts with a key component of the NF-kappaB signalling pathway, namely the IkappaB kinase (IKK)-beta. In co-immunoprecipitations, alpha-catulin can bind IKK-beta and Lbc. Ectopic expression of alpha-catulin augmented NF-kappaB activity, promoted cell migration and increased resistance to apoptosis, whereas knockdown experiments showed the opposite effects. Together, these features suggest that alpha-catulin has tumorigenic potential.
Assuntos
Apoptose/genética , Quinase I-kappa B/metabolismo , NF-kappa B/metabolismo , alfa Catenina/metabolismo , alfa Catenina/fisiologia , Apoptose/efeitos dos fármacos , Movimento Celular/genética , Células Cultivadas , Meios de Cultura Livres de Soro/farmacologia , Citoproteção/genética , Células HeLa , Humanos , Mediadores da Inflamação/metabolismo , Ligação Proteica , Fator Rho/metabolismo , Fator Rho/fisiologia , Transdução de Sinais/fisiologia , Distribuição Tecidual , Transfecção , Fator de Necrose Tumoral alfa/farmacologia , alfa Catenina/genéticaRESUMO
We describe here the identification and initial characterization of a novel human gene termed IKIP (I kappa B kinase interacting protein) that is located on chromosome 12 in close proximity to APAF1 (apoptotic protease-activating factor-1). IKIP and APAF1 share a common 488 bp promoter from which the two genes are transcribed in opposite directions. Three IKIP transcripts are generated by differential splicing and alternative exon usage that do not show significant homology to other genes in the databases. Similar to APAF1, expression of IKIP is enhanced by X-irradiation, and both genes are dependent on p53. Moreover, IKIP promotes apoptosis when transfected into endothelial cells. We conclude that IKIP is a novel p53 target gene with proapoptotic function.
Assuntos
Apoptose/genética , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/metabolismo , Cromossomos Humanos Par 12/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas/genética , Proteína Supressora de Tumor p53/metabolismo , Processamento Alternativo/genética , Sequência de Aminoácidos/genética , Animais , Fator Apoptótico 1 Ativador de Proteases , Sequência de Bases/genética , Proteínas de Transporte/genética , Proteínas de Transporte/isolamento & purificação , Bovinos , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/isolamento & purificação , Linhagem Celular , Sequência Conservada/genética , DNA Complementar/análise , DNA Complementar/genética , Éxons/genética , Regulação da Expressão Gênica/genética , Humanos , Quinase I-kappa B , Camundongos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Isoformas de Proteínas/genética , Proteínas/metabolismo , Ratos , Transdução de Sinais/genética , Transcrição Gênica/genética , Transfecção , Regulação para Cima/genética , Regulação para Cima/efeitos da radiação , Raios X , XenopusRESUMO
Major receptor group common cold virus HRV89 was adapted to grow in HEp-2 cells, which are permissive for minor group human rhinoviruses (HRVs) but which only marginally support growth of major-group viruses. After 32 blind passages in these cells, each alternating with boosts of the recovered virus in HeLa cells, HRV89 acquired the capacity to effectively replicate in HEp-2 cells, attaining virus titers comparable to those in HeLa cells although no cytopathic effect was observed. Several clones were isolated and shown to replicate in HeLa cells whose ICAM-1 was blocked with monoclonal antibody R6.5 and in COS-7 cells, which are devoid of ICAM-1. Blocking experiments with recombinant very-low-density lipoprotein receptor fragments and enzyme-linked immunosorbent assays indicated that the mutants bound a receptor different from that used by minor-group viruses. Determination of the genomic RNA sequence encoding the capsid protein region revealed no changes in amino acid residues at positions equivalent to those involved in the interaction of HRV14 or HRV16 with ICAM-1. One mutation was within the footprint of a very-low-density lipoprotein receptor fragment bound to minor-group virus HRV2. Since ICAM-1 not only functions as a vehicle for cell entry but has also a "catalytic" function in uncoating, the use of other receptors must have important consequences for the entry pathway and demonstrates the plasticity of these viruses.
