RRC ID 39889
Author Kim JK, Ryll R, Ishizuka Y, Kato S.
Title Identification of cDNAs encoding two novel nuclear proteins, IMUP-1 and IMUP-2, upregulated in SV40-immortalized human fibroblasts.
Journal Gene
Abstract Using a model system of young, senescent and SV40-immortalized WI-38 fibroblasts, we identified two mRNAs upregulated in immortalized cells (imup-1, immortalization-upregulated protein 1, and imup-2). Compared to normal tissues, both genes were more frequently expressed in cancer cells. The open reading frame of imup-1 spans 321bp, coding for a 10.9 kDa protein of 106 amino acids, while an insertion of 59bp in the otherwise identical mRNA of imup-2 leads to a frameshift, resulting in an 8.5 kDa protein of 85 amino acids. Database searches identified these genes on chromosome 19, which could account for the cloned imup-1 and imup-2 transcripts by alternative splicing. Southern blot analysis of digested genomic DNA confirmed that both transcripts are derived from a single locus. The expressed proteins IMUP-1 and IMUP-2 share 46 identical N-terminal amino acids, whereas the C-termini are unrelated. Green fluorescent protein-fusions of both IMUP-1 and IMUP-2 accumulated in the nucleus of HeLa cells. The C-terminus of IMUP-1 contains a bipartite nuclear localization signal, the deletion of which impaired nuclear translocation. In-vitro translated proteins bound to poly(rG), but did not interact with single-stranded DNA or double-stranded DNA. The nuclear localization of IMUP-1 and IMUP-2 as well as the upregulation of both underlying mRNAs in immortalized cells suggest a function in immortalization.
Volume 257(2)
Pages 327-34
Published 2000-10-31
DOI 10.1016/s0378-1119(00)00414-5
PII S0378-1119(00)00414-5
PMID 11080599
MeSH Alternative Splicing Amino Acid Sequence Base Sequence Cell Line Cell Transformation, Viral DNA, Complementary / chemistry DNA, Complementary / genetics* DNA, Complementary / isolation & purification Female Fibroblasts / cytology Fibroblasts / metabolism* Gene Expression Regulation, Developmental Genes / genetics Green Fluorescent Proteins HeLa Cells Humans Luminescent Proteins / genetics Luminescent Proteins / metabolism Male Molecular Sequence Data Nuclear Proteins / genetics* Nuclear Proteins / metabolism Nucleic Acids / metabolism Poly G / metabolism Protein Binding Protein Biosynthesis Protein Isoforms / genetics RNA, Messenger / genetics RNA, Messenger / metabolism Recombinant Fusion Proteins / genetics Recombinant Fusion Proteins / metabolism Reverse Transcriptase Polymerase Chain Reaction Sequence Analysis, DNA Simian virus 40 / genetics Tissue Distribution Tumor Cells, Cultured
IF 2.984
Times Cited 13
Human and Animal Cells MRC-5 SV1 TG1(RCB0207) NB1RGB(RCB0222) PSV811(RCB023) W-V(RCB0252)