Coexpression of the CUG-binding protein reduces DM protein kinase expression in COS cells.
Myotonic dystrophy (DM) is the most common form of adult onset muscular dystrophy. Patients have a large CTG repeat expansion in the 3' untranslated region of the DMPK gene, which encodes DM protein kinase. RNA trans-dominant models, which hypothesize that the expanded CUG trinucleotide repeat on DMPK mRNA sequesters a factor or disrupts the RNA metabolism of the DMPK mRNA itself and other mRNAs in a trans dominant manner, have been proposed. A candidate for the sequestered factor, termed CUG-binding protein (CUG-BP), exists in several alternatively spliced isoforms. We found a human isoform with a twelve base insertion (deduced amino acids Leu-Tyr-Leu-Gln) and an isoform with a three base insertion (deduced amino acid Ala) insertion. In order to elucidate the effects of CUG-BP on DMPK expression, we introduced CUG-BP and DMPK cDNA transiently into COS-7 cells. Cotransfection of CUG-BP did not significantly affect the expression of either wild type or mutant DMPK at the mRNA level. On the other hand, cotransfection of CUG-BP significantly affected the expression of both the wild type and mutant DMPKs at the protein level. This reduction was remarkable when the mutant DMPK construct was used.
Takahashi
N
N
Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Sasagawa
N
N
Usuki
F
F
Kino
Y
Y
Kawahara
H
H
Sorimachi
H
H
Maeda
T
T
Suzuki
K
K
Ishiura
S
S
D000818:Animals; D001483:Base Sequence; D000067879:CELF1 Protein; D019556:COS Cells; D002522:Chlorocebus aethiops; D015536:Down-Regulation; D015870:Gene Expression; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009223:Myotonic Dystrophy / Q000235:genetics; D065636:Myotonin-Protein Kinase; D011061:Poly A / Q000235:genetics; D014176:Protein Biosynthesis; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D016601:RNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D012261:Ribonucleoproteins / Q000096:biosynthesis* / Q000235:genetics; D014018:Tissue Distribution; D018911:Trinucleotide Repeats / Q000235:genetics
D000067879:CELF1 Protein; C102843:CELF1 protein, human; C585517:DMPK protein, human; C585516:DMPK protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D011061:Poly A; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases