Rbfox1 Is Expressed in the Mouse Brain in the Form of Multiple Transcript Variants and Contains Functional E Boxes in Its Alternative Promoters

The RNA-binding protein RBFOX1 is an important regulator of neuron development and neuronal excitability. Rbfox1 is a dosage-sensitive gene and in both mice and humans, decreased expression of Rbfox1 has been linked to neurodevelopmental disorders. Alternative promoters drive expression of Rbfox1 transcript isoforms that encode an identical protein. The tissue- and developmental stage-specific expression of these isoforms, as well as the underlying regulatory mechanisms, are, however, unclear. Here, we set out to capture all of the Rbfox1 transcript isoforms and identify transcriptional mechanisms that regulate brain-specific Rbfox1 expression. Isoform sequencing identified multiple alternative Rbfox1 transcript variants in the mouse cerebral cortex, including transcripts with novel first exons, alternatively spliced exons and 3′-truncations. Quantitative RT-PCR determined the expression of the alternative first exons in the developing cerebral cortex and different subregions of the juvenile brain. Alternative first exons were found to be highly stage- and subregion specific in their expression patterns suggesting that they fulfill specific functions during cortex development and in different brain regions. Using reporter assays we found that the promoter regions of the two first exons E1B and E1C/E1C.1 contain several functional E-boxes. Together, we provide an extensive picture of Rbfox1 isoform expression. We further identified important regulatory mechanisms that drive neuron-specific Rbfox1 expression. Thus, our study forms the basis for further research into the mechanisms that ensure physiological Rbfox1 expression in the brain. It also helps to understand why, in patients with neurodevelopmental disorders deletion of individual RBFOX1 transcript isoforms could affect brain function.

Identification of a classic nuclear localization signal at the N terminus that regulates the subcellular localization of Rbfox2 isoforms during differentiation of NMuMG and P19 cells

Nuclear localization of the alternative splicing factor Rbfox2 is achieved by a C-terminal nuclear localization signal (NLS) which can be excluded from some Rbfox2 isoforms by alternative splicing. While this predicts nuclear and cytoplasmic localization, Rbfox2 is exclusively nuclear in some cell types. Here, we identify a second NLS in the N terminus of Rbfox2 isoform 1A that is not included in Rbfox2 isoform 1F. Rbfox2 1A isoforms lacking the C-terminal NLS are nuclear, whereas equivalent 1F isoforms are cytoplasmic. A shift in Rbfox2 expression toward cytoplasmic 1F isoforms occurs during epithelial to mesenchymal transition (EMT) and could be important in regulating the activity and function of Rbfox2.

[Soft neurological signs: are they of any value in the assessment and diagnosis of attention deficit hyperactivity disorder?]

INTRODUCTION

The association between difficulties on motor skills, visual-hand coordination and excess motor activity was described previously of being established the attention-deficit/hyperactivity disorder (ADHD) as a diagnostic category. These disorders have been grouped under different terminologies, being one of them the soft neurological signs (SNS). Traditionally, the European scientific community has put more attention on the SNS than the American one. However, nowadays there are a lot of neuropediatrician and community pediatrician that continue to think that those deficits, together with inattention and hyperactivity, form part of the same disorder.

DEVELOPMENT

In this article we have tried to do a neurobiological revision of the movement and the possible relationship between motor problems and cognitive processes from different points of view: neuroanatomical, findings on different clinical examination tests and neuropsychological experimental models.

CONCLUSION

Most of the revised articles conclude that the SNS prevalence is greater in ADHD children compared with control. Therefore we recommend to include the SNS in the evaluation and diagnosis protocols of these disorders in order to improve the sensitivity and specificity of the diagnosis and to be able to evaluate the real needs of the ADHD patients.