MBNL1 associates with YB-1 in cytoplasmic stress granules.
The muscleblind-like (MBNL) protein family is thought to be involved in the molecular mechanism of myotonic dystrophy (DM). Although it has been shown to have splicing activity, a broader function in cellular RNA metabolism has been implicated. In this study, we attempted to find the binding proteins of MBNL1 in order to elucidate its physiological function. First, we performed a GST pull-down assay using GST-MBNL1-6xHis as bait. Several proteins were identified, including YB-1, a multifunctional DNA/RNA-binding protein, and DDX1, a DEAD box RNA helicase. MBNL1 formed an RNP complex with YB-1 and DDX1 in binding assays. YB-1 also showed a weak but significant effect on alpha-actinin splice site selection. Interestingly, in response to stress, MBNL1 moved to cytoplasmic stress granules, where it colocalized with YB-1, which was previously reported to be a component of stress granules. We found that DDX1 also colocalized with MBNL1 at stress granules. These results provide new insight into the dynamics of MBNL1 in response to stress, and they suggest a role for MBNL1 in mRNA metabolism in the cytoplasm.
Onishi
Hayato
H
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
Kino
Yoshihiro
Y
Morita
Tomoko
T
Futai
Eugene
E
Sasagawa
Noboru
N
Ishiura
Shoichi
S
D003594:Cytoplasmic Granules / Q000502:physiology*; D053487:DEAD-box RNA Helicases / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005784:Gene Amplification; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins; D011132:Polyribosomes / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D000074019:T-Cell Intracellular Antigen-1; D051840:Y-Box-Binding Protein 1
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C493663:MBNL1 protein, human; D009687:Nuclear Proteins; D039102:Poly(A)-Binding Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000074019:T-Cell Intracellular Antigen-1; C071558:TIA1 protein, human; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; C086252:DDX1 protein, human; D053487:DEAD-box RNA Helicases