The truncation that generated the v-cbl oncogene reveals an ability for nuclear transport, DNA binding and acute transformation.
The v-cbl oncogene is the transforming gene of the murine Cas NS-1 retrovirus which induces pre-B cell lymphomas and myeloid leukaemias. Sequencing of c-cbl has revealed that v-cbl was generated by a large truncation that removed 60% of the C-terminus of the corresponding protein. In this study we prepared antibodies to cbl and found that c-cbl encodes a 120 kDa protein which is localized in the cytoplasm with a cytosolic and cytoskeletal distribution. Immunofluorescence studies show a striking pattern of brightly staining vesicles in mitotic cells similar to that observed with cytokeratin antibodies. In contrast to p120c-cbl, which is exclusively cytoplasmic, the p100gag-v-cbl encoded by Cas NS-1 is localized in both the cytoplasm and the nucleus. This redistribution to the nucleus correlates with the ability of cbl to induce acute transformation. Furthermore the truncated protein encoded by v-cbl can bind DNA, unlike the full-length protein. These results suggest that the C-terminus of cbl is involved in the retention of p120c-cbl in the cytoplasm and the inhibition of DNA binding. The findings also suggest that a truncated protein encoded by c-cbl exists in the nucleus of normal cells.
Blake
T J
TJ
Hanson Centre for Cancer Research, IMVS, Adelaide, Australia.
Heath
K G
KG
Langdon
W Y
WY
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D002467:Cell Nucleus / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D050722:Oncogene Protein v-cbl; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology; D050721:Proto-Oncogene Proteins c-cbl; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
D000906:Antibodies; D050722:Oncogene Protein v-cbl; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D015682:Retroviridae Proteins, Oncogenic; D004247:DNA; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; C067419:CBL protein, human; C493849:Cbl protein, mouse