A fission yeast homolog of Int-6, the mammalian oncoprotein and eIF3 subunit, induces drug resistance when overexpressed.

Journal article

Through a screen to identify genes that induce multi-drug resistance when overexpressed, we have identified a fission yeast homolog of Int-6, a component of the human translation initiation factor eIF3. Disruption of the murine Int-6 gene by mouse mammary tumor virus (MMTV) has been implicated previously in tumorigenesis, although the underlying mechanism is not yet understood. Fission yeast Int6 was shown to interact with other presumptive components of eIF3 in vivo, and was present in size fractions consistent with its incorporation into a 43S translation preinitiation complex. Drug resistance induced by Int6 overexpression was dependent on the AP-1 transcription factor Pap1, and was associated with increased abundance of Pap1-responsive mRNAs, but not with Pap1 relocalization. Fission yeast cells lacking the int6 gene grew slowly. This growth retardation could be corrected by the expression of full length Int6 of fission yeast or human origin, or by a C-terminal fragment of the fission yeast protein that also conferred drug resistance, but not by truncated human Int-6 proteins corresponding to the predicted products of MMTV-disrupted murine alleles. Studies in fission yeast may therefore help to explain the ways in which Int-6 function can be perturbed during MMTV-induced mammary tumorigenesis.

Authors: Crane, R; Craig, R; Murray, R; Dunand-Sauthier, I; Humphrey, T

• Publication status: Published
• Journal: Molecular biology of the cell
• Volume: 11
• Issue: 11
• Pages: 3993-4003
• Publication date: 2000-11-01
• DOI: 10.1091/mbc.11.11.3993
• EISSN: 1939-4586
• ISSN: 1059-1524
• Language: English
• Keywords: Schizosaccharomyces pombe Proteins; Carbamates; DNA-Binding Proteins; Drug Resistance, Microbial; Eukaryotic Initiation Factor-3; Proto-Oncogene Proteins; Amino Acid Sequence; Benzimidazoles; Gene Expression Regulation, Fungal; Prokaryotic Initiation Factor-3; Fungal Proteins; Up-Regulation; Peptide Initiation Factors; Humans; Cytoplasm; Base Sequence; Mammary Tumor Virus, Mouse; Basic-Leucine Zipper Transcription Factors; Sequence Homology, Amino Acid; Cell Division; Schizosaccharomyces; Molecular Sequence Data; Fungicides, Industrial