The Rbfox1 gene: expression analysis and study of the transcriptional regulation
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Abstract
The RBFOX1 gene, which is located on chromosome 16p13.2, encodes an RNA-binding protein that regulates pre-mRNA splicing events in specific cell types including neurons. In the mouse, the gene contains a large noncoding part in its 5' end with at least four alternative promoters, promoters 1B, 1C, 1D and 1E. Promoters 1B, 1C and 1D are brain specific and promoter 1E is muscle specific. The promoters drive the expression of the alternative Rbfox1 transcript isoforms, which differ in their 5'UTR but not in their coding exons. Copy number variants (CNVs) in the human RBFOX1 gene that are located in the 5'-noncoding part of the gene and that typically only affect some but not all RBFOX1 transcript isoforms, have been associated with a range of neurodevelopmental disorders such as autism spectrum disorder, intellectual disability, epilepsy, attention deficit hyperactivity disorder and schizophrenia.
In this thesis, I analyzed the expression of the three brain-specific Rbfox1 transcript isoforms controlled by the promoters 1B, 1C and 1D during embryonic development of the cerebral cortex as well as in various brain regions of the juvenile mouse. Furthermore, through in silico analysis and luciferase assays, I characterized the alternative Rbfox1 promoters and demonstrated that the expression of Rbfox1 in primary cortical neurons is driven by promoters 1B and 1C. I identified three transcription factors (C-MYC, NEUROD2 and TCF4) that regulate the expression of Rbfox1 in cortical neurons. Using transcript-specific studies, I was able to show that TCF4 regulates the expression of transcripts 1B and 1C, whereas NEUROD2 only controls the expression of transcript 1B.