Interaction of muscleblind, CUG-BP1 and hnRNP H proteins in DM1-associated aberrant IR splicing.
In myotonic dystrophy (DM1), both inactivation of muscleblind proteins and increased levels of CUG-BP1 are reported. These events have been shown to contribute independently to aberrant splicing of a subset RNAs. We demonstrate that steady-state levels of the splice regulator, hnRNP H, are elevated in DM1 myoblasts and that increased hnRNP H levels in normal myoblasts results in the inhibition of insulin receptor (IR) exon 11 splicing in a manner similar to that observed in DM1. In normal myoblasts, overexpression of either hnRNP H or CUG-BP1 results in the formation of an RNA-dependent suppressor complex consisting of both hnRNP H and CUG-BP1, which is required to maximally inhibit IR exon 11 inclusion. Elevated levels of MBNL1 show RNA-independent interaction with hnRNP H and dampen the inhibitory activity of increased hnRNP H levels on IR splicing in normal myoblasts. In DM1 myoblasts, overexpression of MBNL1 in conjunction with si-RNA mediated depletion of hnRNP H contributes to partial rescue of the IR splicing defect. These data demonstrate that coordinated physical and functional interactions between hnRNP H, CUG-BP1 and MBNL1 dictate IR splicing in normal and DM1 myoblasts.
Paul
Sharan
S
Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
Dansithong
Warunee
W
Kim
Dongho
D
Rossi
John
J
Webster
Nicholas J G
NJ
Comai
Lucio
L
Reddy
Sita
S
D001483:Base Sequence; D000067879:CELF1 Protein; D002478:Cells, Cultured; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D046912:Multiprotein Complexes; D032446:Myoblasts / Q000378:metabolism; D009223:Myotonic Dystrophy / Q000235:genetics / Q000378:metabolism; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism*; D012326:RNA Splicing; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011972:Receptor, Insulin / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D000067879:CELF1 Protein; C102843:CELF1 protein, human; C585517:DMPK protein, human; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; C493663:MBNL1 protein, human; D046912:Multiprotein Complexes; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D011972:Receptor, Insulin; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases