Negative autoregulation of BMP dependent transcription by SIN3B splicing reveals a role for RBM39.
BMP signalling is negatively autoregulated by several genes including SMAD6, Noggin and Gremlin, and autoregulators are possible targets for enhancing BMP signalling in disorders such as fibrosis and pulmonary hypertension. To identify novel negative regulators of BMP signalling, we used siRNA screening in mouse C2C12 cells with a BMP-responsive luciferase reporter. Knockdown of several splicing factors increased BMP4-dependent transcription and target gene expression. Knockdown of RBM39 produced the greatest enhancement in BMP activity. Transcriptome-wide RNA sequencing identified a change in Sin3b exon usage after RBM39 knockdown. SIN3B targets histone deacetylases to chromatin to repress transcription. In mouse, Sin3b produces long and short isoforms, with the short isoform lacking the ability to recruit HDACs. BMP4 induced a shift in SIN3B expression to the long isoform, and this change in isoform ratio was prevented by RBM39 knockdown. Knockdown of long isoform SIN3B enhanced BMP4-dependent transcription, whereas knockdown of the short isoform did not. We propose that BMP4-dependent transcription is negatively autoregulated in part by SIN3B alternative splicing, and that RBM39 plays a role in this process.
Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
Noel
N
Faherty
Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.|Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
Matthew
M
Benson
Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.|Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
Eshita
E
Sharma
Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
Angela
A
Lee
Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.|Target Discovery Institute, University of Oxford, Oxford, United Kingdom.
Alison
A
Howarth
Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.|Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
Helen
H
Lockstone
Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.|Target Discovery Institute, University of Oxford, Oxford, United Kingdom.
Daniel
D
Ebner
Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
Shoumo
S
Bhattacharya
D017398:Alternative Splicing; D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics*; D045744:Cell Line, Tumor; D002843:Chromatin / Q000235:genetics; D025461:Feedback, Physiological; D005355:Fibrosis; D006655:Histone Deacetylases / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D006976:Hypertension, Pulmonary / Q000235:genetics* / Q000378:metabolism; D008168:Lung / Q000473:pathology*; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics*; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics*; D015398:Signal Transduction; D051905:Smad6 Protein / Q000235:genetics
C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D002843:Chromatin; C084105:HCC1 autoantigen; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C115812:Sin3b protein, mouse; D051905:Smad6 Protein; C497803:Smad6 protein, mouse; D006655:Histone Deacetylases