Project description:To investigate the role of srrm3 as a regulator of retina microexons (RetMICs) we have sequenced adult retina from WT animals, and enucleated eyes from 5 dpf larvae WT and KO for srrm3.
Project description:To investigate the role of MSI1, SRRM3 and SRRM4 as a regulator of retina microexons (RetMICs) in vitro in humans, we have ectopically expressed these genes in HEK293 cells and performed RNA-seq.
Project description:The mechanisms by which entire programs of gene regulation emerged during evolution are poorly understood. Neuronal microexons represent the most conserved class of alternative splicing in vertebrates and are critical for proper brain development and function. Here, we discover neural microexon programs in non-vertebrate species and trace their origin to bilaterian ancestors through the emergence of a previously uncharacterized ‘enhancer of microexons' (eMIC) protein domain. The eMIC domain originated as an alternative, neural-enriched splice isoform of the pan-eukaryotic Srrm2/SRm300 splicing factor gene, and subsequently became fixed in the vertebrate and neuronal-specific splicing regulator Srrm4/nSR100 and its paralog Srrm3. Remarkably, the eMIC domain is necessary and sufficient for microexon splicing, and functions by interacting with the earliest components required for exon recognition. The emergence of a novel domain with restricted expression in the nervous system thus resulted in the evolution of splicing programs that contributed to qualitatively expand neuronal molecular complexity in bilaterians.
Project description:Interrupted exons in the pre-mRNA transcripts are ligated together through RNA splicing, which plays critical roles in the regulation of gene expression. Exons with length ≤30 nt are defined as microexons that are unique in identifications and gene functions. However, due to difficulties in mapping short segments from sequencing reads, microexons especially shorter than 8 nt, have not been well studied in many organisms. Here, we analyzed mRNA-seq data from a variety of Drosophila samples by a new developed bioinformatic tool, ce-TopHat. In addition to the Flybase annotated, 465 new microexons were identified. Differentially alternatively spliced (AS) microexons were investigated between the Drosophila tissues (head, body and gonad) and genders. Most of the AS microexons are found in the head, as well as two AS microexons were identified in the sex-determination pathway gene fruitless.
Project description:The Bronx waltzer mutation in Srrm4, a gene that encodes a neuronal Ser/Arg (SR)-rich splicing factor, disrupts the expression of several alternative exons specifically in the inner ear. Here we show that the expression of SRRM3 in neurons limits the distribution of SRRM4-dependent splicing. In vitro, SRRM3 and SRRM4 regulated the same alternative exons, yet in vivo Srrm3 deficiency caused neuronal splicing alterations and motor dysfunction, indicating that SRRM3 has non-redundant functions. Mice harboring mutations in both Srrm3 and Srrm4 failed to breathe, and their neuromuscular junctions (NMJ) were malformed. Transcriptome-wide analysis revealed a large network of SRRM3/SRRM4-dependent splicing changes, including the skipping of key exons in the NMJ organizer Agrin. Furthermore, SRRM3/SRRM4 regulated gene expression through neuron-specific switches in chromatin regulatory complexes and by altering the reading frame in several mRNAs. Our findings reveal that the SRRM3/SRRM4 subfamily of SR proteins is central to regulation of the neuronal transcriptome. In this dataset, we include probe-set level data obtained from cerebellar samples. The processed data represent probe-set intensities that have been normalized to gene expression levels.
Project description:The Bronx waltzer mutation in Srrm4, a gene that encodes a neuronal Ser/Arg (SR)-rich splicing factor, disrupts the expression of several alternative exons specifically in the inner ear. Here we show that the expression of SRRM3 in neurons limits the distribution of SRRM4-dependent splicing. In vitro, SRRM3 and SRRM4 regulated the same alternative exons, yet in vivo Srrm3 deficiency caused neuronal splicing alterations and motor dysfunction, indicating that SRRM3 has non-redundant functions. Mice harboring mutations in both Srrm3 and Srrm4 failed to breathe, and their neuromuscular junctions (NMJ) were malformed. Transcriptome-wide analysis revealed a large network of SRRM3/SRRM4-dependent splicing changes, including the skipping of key exons in the NMJ organizer Agrin. Furthermore, SRRM3/SRRM4 regulated gene expression through neuron-specific switches in chromatin regulatory complexes and by altering the reading frame in several mRNAs. Our findings reveal that the SRRM3/SRRM4 subfamily of SR proteins is central to regulation of the neuronal transcriptome. In this dataset, we include probe-set level data obtained from brain cortex samples. The processed data represent probe-set intensities that have been normalized to gene expression levels.