Selective translational repression of truncated proteins from frameshift mutation-derived mRNAs in tumors.
Frameshift and nonsense mutations are common in tumors with microsatellite instability, and mRNAs from these mutated genes have premature termination codons (PTCs). Abnormal mRNAs containing PTCs are normally degraded by the nonsense-mediated mRNA decay (NMD) system. However, PTCs located within 50-55 nucleotides of the last exon-exon junction are not recognized by NMD (NMD-irrelevant), and some PTC-containing mRNAs can escape from the NMD system (NMD-escape). We investigated protein expression from NMD-irrelevant and NMD-escape PTC-containing mRNAs by Western blotting and transfection assays. We demonstrated that transfection of NMD-irrelevant PTC-containing genomic DNA of MARCKS generates truncated protein. In contrast, NMD-escape PTC-containing versions of hMSH3 and TGFBR2 generate normal levels of mRNA, but do not generate detectable levels of protein. Transfection of NMD-escape mutant TGFBR2 genomic DNA failed to generate expression of truncated proteins, whereas transfection of wild-type TGFBR2 genomic DNA or mutant PTC-containing TGFBR2 cDNA generated expression of wild-type protein and truncated protein, respectively. Our findings suggest a novel mechanism of gene expression regulation for PTC-containing mRNAs in which the deleterious transcripts are regulated either by NMD or translational repression.
You
Kwon Tae
KT
Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
Li
Long Shan
LS
Kim
Nam-Gyun
NG
Kang
Hyun Ju
HJ
Koh
Kwi Hye
KH
Chwae
Yong-Joon
YJ
Kim
Kyoung Mi
KM
Kim
Yoon Ki
YK
Park
Sung Mi
SM
Jang
Sung Key
SK
Kim
Hoguen
H
D020413:3' Untranslated Regions / Q000502:physiology; D017766:Acid Anhydride Hydrolases; D045744:Cell Line, Tumor; D018388:Codon, Terminator / Q000502:physiology*; D015179:Colorectal Neoplasms / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D016368:Frameshift Mutation / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000096:biosynthesis; D053842:Microsatellite Instability; D000074081:MutS Homolog 3 Protein; D020125:Mutation, Missense; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009363:Neoplasm Proteins / Q000032:analysis; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020413:3' Untranslated Regions; D018388:Codon, Terminator; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C000619710:MARCKS protein, human; C078444:MSH3 protein, human; D008565:Membrane Proteins; D000074081:MutS Homolog 3 Protein; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes