Protein truncation is not required for c-myb proto-oncogene activity in neuroretina cells.
The v-myb oncogene of avian myeloblastosis virus (AMV) differs from its normal cellular counterpart by a truncation at both its amino and carboxyl termini and by a substitution of 11 amino acid residues. We had previously shown that v-myb-containing AMV, in the presence of basic fibroblast growth factor, transformed chicken neuroretina (CNR) cells. To understand the mechanism of c-myb activation, we have tested whether avian retroviruses that express the full-length c-Myb are also active on CNR cells. We have found that c-Myb, like v-Myb, strongly increases the basic fibroblast growth factor response of CNR cells and that these c-myb-expressing cells are able to grow in soft agar in the presence of the growth factor. We have also found that, in contrast to normal or v-myb-expressing AMV-transformed CNR cells, c-Myb-transformed cells express mim-1, a granulocyte-specific gene. However, normal v-Myb- and c-Myb-expressing CNR cells all express the pax-QNR gene, a newly described paired and homeobox-containing gene specifically expressed in the neuroretina. We conclude that, in contrast to what has been described for hematopoietic cells, overexpression of c-Myb is sufficient to activate gene expression and to induce an abnormal behavior of CNR cells.
Garrido
C
C
CNRS URA 1160, Institut Pasteur de Lille, France.
Grässer
F
F
Lipsick
J S
JS
Stehelin
D
D
Saule
S
S
D009189:Avian Myeloblastosis Virus / Q000235:genetics* / Q000378:metabolism; D002471:Cell Transformation, Neoplastic; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D012160:Retina / Q000382:microbiology*; D013329:Structure-Activity Relationship; D014162:Transfection; D014764:Viral Proteins / Q000096:biosynthesis
D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D014764:Viral Proteins; D016222:Fibroblast Growth Factor 2