H-Ras-specific activation of NF-kappaB protects NIH 3T3 cells against stimulus-dependent apoptosis.
Ras signaling involves the activation of several downstream pathways that exhibit isoform specificity. In this study, the basal and tumor necrosis factor alpha (TNFalpha)-induced activation of NF-kappaB has been examined in cells overexpressing H-Ras, K-Ras or N-Ras. Cells expressing H-Ras exhibited a basal kappaB activity that correlated with sustained IkappaB kinase activation and lower steady-state levels of IkappaBalpha in the cytosol. Upon activation with TNFalpha, the cells expressing the distinct Ras isoforms behaved similarly in terms of binding of nuclear proteins to a kappaB sequence and induction of a kappaB-dependent reporter gene. The basal activation of NF-kappaB in cells expressing H-Ras impaired staurosporine-induced apoptosis in these cells, through a mechanism that was NF-kappaB-dependent and inhibitable in the presence of z-VAD. Moreover, titration of caspase activation in response to staurosporine showed a significant resistance in cells expressing H-Ras when compared with the void vector or the N-Ras counterparts. These results indicate that the distinct Ras proteins have specific effects on the NF-kappaB pathway and that this action contributes to protect cells against apoptosis.
Millán
Olga
O
Instituto de Bioquímica, Centro Mixto CSIC-UCM, Universidad Complutense, Madrid, Spain.
Ballester
Alicia
A
Castrillo
Antonio
A
Oliva
José Luis de la
JL
Través
Paqui G
PG
Rojas
José María
JM
Boscá
Lisardo
L
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D015689:Oncogene Protein p21(ras) / Q000502:physiology*; D010957:Plasmids; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D017931:DNA Primers; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D015689:Oncogene Protein p21(ras)