Project description:SVA retrotransposon insertion-associated deletion represents a novel mutational mechanism underlying large genomic copy number changes with non-recurrent breakpoints
Project description:The mismatch repair (MMR) family is a highly conserved group of proteins that function in correcting base-base and insertion-deletion mismatches generated during DNA replication. To systematically investigate the mismatch repair pathway, we conducted a proteomic analysis and identified MMR-associated protein complexes using a tandem-affinity purification coupled with mass spectrometry (TAP-MS) method. In total, we identified 262 high-confidence candidate interaction proteins (HCIPs).
Project description:The mismatch repair (MMR) family is a highly conserved group of proteins that function in correcting base-base and insertion-deletion mismatches generated during DNA replication. To systematically investigate the mismatch repair pathway, we conducted a proteomic analysis and identified MMR-associated protein complexes using a tandem-affinity purification coupled with mass spectrometry (TAP-MS) method. In total, we identified 262 high-confidence candidate interaction proteins (HCIPs).
Project description:X-linked dystonia-parkinsonism is a neurodegenerative disease, which is caused by a SVA retrotransposon insertion within TAF1, gene encoding an integral component of the basal transcription factor TFIID. The SVA insertion has been shown to induce defects both in biosynthesis and in alternative splicing of TAF1 mRNA in various cell types. This includes the reduction of a neuron-specific isoform of TAF1 mRNA generated by inclusion of the evolutionary conserved microexon 34’ (TAF1-34’). In this study, we investigated the tissue distribution of TAF1-34’ mRNA and protein and the neuron-specific mechanism sustaining its alternative splicing. Using isoform-specific RNA probes and antibodies, we observe that canonical TAF1 and TAF1-34’ have different distributions in the brain. To our knowledge, this is the first in situ detection of a microexon. We find that the differential expression of these two isoforms distinguishes proliferating from post-mitotic neurons in vitro and in vivo. Knockdown and ectopic expression experiments in cell lines demonstrated that the neuron-specific splicing factor nSR100/SRRM4 is directing the inclusion of microexon 34’ into TAF1 mRNA. These results show that SRRM4 regulates temporal and spatial distribution of alternative TAF1 mRNAs to generate a neuron-specific isoform of basal transcription factor TFIID.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes