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TGS1 controls snRNA 3' end processing, prevents neurodegeneration and ameliorates SMN-dependent neurological phenotypes in vivo (Illumina)

ABSTRACT: Trimethylguanosine synthase 1 (TGS1) is a highly conserved enzyme that converts the 5' mono-methylguanosine cap of snRNAs to a trimethylguanosine cap. Here, we show that loss of TGS1 in C. elegans, D. melanogaster and D. rerio results in neurological phenotypes similar to those caused by Survival Motor Neuron (SMN) deficiency. Importantly, expression of human TGS1 ameliorates the SMN-dependent neurological phenotypes in both flies and worms, revealing that TGS1 can partly counteract the effects of SMN deficiency. TGS1 loss in HeLa cells leads to the accumulation of immature U2 and U4atac snRNAs with long 3' tails that are often uridylated. snRNAs with defective 3' terminations also accumulate in Drosophila Tgs1 mutants. Consistent with defective snRNA maturation, TGS1 and SMN mutant cells also exhibit partially overlapping transcriptome alterations that include aberrantly spliced and readthrough transcripts. Together, these results identify a neuroprotective function for TGS1 and reinforce the view that defective snRNA maturation affects neuronal viability and function.

ORGANISM(S): Homo sapiens

PROVIDER: GSE189413 | GEO | 2022/07/15

REPOSITORIES: GEO

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TGS1 controls snRNA 3' end processing, prevents neurodegeneration and ameliorates SMN-dependent neurological phenotypes in vivo (Nanopore)

Project description:Trimethylguanosine synthase 1 (TGS1) is a highly conserved enzyme that converts the 5' mono-methylguanosine cap of snRNAs to a trimethylguanosine cap. Here, we show that loss of TGS1 in C. elegans, D. melanogaster and D. rerio results in neurological phenotypes similar to those caused by Survival Motor Neuron (SMN) deficiency. Importantly, expression of human TGS1 ameliorates the SMN-dependent neurological phenotypes in both flies and worms, revealing that TGS1 can partly counteract the effects of SMN deficiency. TGS1 loss in HeLa cells leads to the accumulation of immature U2 and U4atac snRNAs with long 3' tails that are often uridylated. snRNAs with defective 3' terminations also accumulate in Drosophila Tgs1 mutants. Consistent with defective snRNA maturation, TGS1 and SMN mutant cells also exhibit partially overlapping transcriptome alterations that include aberrantly spliced and readthrough transcripts. Together, these results identify a neuroprotective function for TGS1 and reinforce the view that defective snRNA maturation affects neuronal viability and function.

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Loss of the RNA trimethylguanosine cap is compatible with nuclear accumulation of spliceosomal snRNAs but not pre-mRNA splicing or snRNA processing during animal development

Project description:The 2,2,7-trimethylguanosine (TMG) cap is synthesized by the conserved Tgs1 enzyme, which is abundantly present on snRNAs essential for pre-mRNA splicing. In our study, we characterize new mutations in the Drosophila tgs1 gene and studied their effects on development and on splicing. Utilizing a hypomorphic tgs1 mutation, we uncovered a prominent role of Tgs1 in pre-mRNA splicing, particularly of introns with smaller sizes and weaker splice sites. Remarkably, stronger tgs1 mutations generated by CRISPR-Cas9 cause lethality without disrupting splicing, likely due to the preponderance of a maternal contribution and stable TMG capped snRNAs maintaining a near normal level of TMG modified snRNAs, which further proved that the TMG modification is important in splicing.

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2024-05-16 | GSE191019 | GEO

TGS1 controls snRNA 3' end processing, prevents neurodegeneration and ameliorates SMN-dependent neurological phenotypes in vivo (Nanopore)

Project description:TGS1 controls snRNA 3' end processing, prevents neurodegeneration and ameliorates SMN-dependent neurological phenotypes in vivo (Nanopore)

| PRJNA781631 | ENA

TGS1 controls snRNA 3' end processing, prevents neurodegeneration and ameliorates SMN-dependent neurological phenotypes in vivo (Illumina)

Project description:TGS1 controls snRNA 3' end processing, prevents neurodegeneration and ameliorates SMN-dependent neurological phenotypes in vivo (Illumina)

| PRJNA782971 | ENA

Hypermethylated capped selenoprotein mRNAs in mammals

Project description:Mammalian mRNAs are generated by complex and coordinated biogenesis pathways and acquire 5'-end m7G caps that play fundamental roles in processing and translation. Here we show that several selenoprotein mRNAs are not recognized efficiently by translation initiation factor eIF4E because they bear a hypermethylated cap. This cap modification is acquired via a 5’end maturation pathway similar to that of the small nucle(ol)ar RNAs (sn- and snoRNAs). Our findings also establish that the trimethylguanosine synthase 1 (Tgs1) interacts with selenoprotein mRNAs for cap hypermethylation and that assembly chaperones and core proteins devoted to sn- and snoRNP maturation contribute to recruiting Tgs1 to selenoprotein mRNPs. We further demonstrate that the hypermethylated-capped selenoprotein mRNAs localize to the cytoplasm, are associated with polysomes and thus translated. Moreover, we found that the activity of Tgs1, but not of eIF4E, is required for the synthesis of the GPx1 selenoprotein in vivo.

2014-05-14 | GSE57625 | GEO

Compound heterozygous mutations in the noncoding RNU4ATAC gene affect the homeostasis and function of the Integrator complex

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2022-12-01 | GSE197344 | GEO

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