Identification of putative c-Myc-responsive genes: characterization of rcl, a novel growth-related gene.
The c-Myc protein is a helix-loop-helix leucine zipper oncogenic transcription factor that participates in the regulation of cell proliferation, differentiation, and apoptosis. The biochemical function of c-Myc has been well described, yet the identities of downstream effectors are just beginning to emerge. We describe the identification of a set of c-Myc-responsive genes in the Rat1a fibroblast through the application of cDNA representational difference analysis (RDA) to cDNAs isolated from nonadherent Rat1a and Rat1a-myc cells. In this system, c-Myc overexpression is sufficient to induce the transformed phenotype of anchorage-independent growth. We identified 20 differentially expressed cDNAs, several of which represent novel cDNA sequences. We further characterized one of the novel cDNAs identified in this screen, termed rcl. rcl expression is (i) directly stimulated by c-Myc; (ii) stimulated in the in vivo growth system of regenerating rat liver, as is c-myc; and (iii) elevated in human lymphoid cells that overexpress c-myc. By using an anti-Rcl antibody, immunoblot analysis, and immunofluorescence microscopy, the Rcl protein was found to be a 23-kDa nuclear protein. Ectopic expression of the protein encoded by the rcl cDNA induces anchorage-independent growth in Rat1a fibroblasts, albeit to a diminished extent compared to ectopic c-Myc expression. These data suggest a role for rcl during cellular proliferation and c-Myc-mediated transformation.
Lewis
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BC
Department of Medicine, Program in Human Genetics and Molecular Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Shim
H
H
Li
Q
Q
Wu
C S
CS
Lee
L A
LA
Maity
A
A
Dang
C V
CV
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D005347:Fibroblasts / Q000166:cytology; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism; D016415:Sequence Alignment
D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D012260:Ribonucleases; C107935:DNPH1 protein, human; C518894:DNPH1 protein, rat; D009699:N-Glycosyl Hydrolases