What’s new in pontocerebellar hypoplasia? An update on genes and subtypes

Dijk, Tessa van; Baas, Frank; Barth, Peter; Poll-Thé, Bwee Tien

doi:10.1186/s13023-018-0826-2

Cited by 126 publications

(137 citation statements)

References 111 publications

(202 reference statements)

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“…There is no curative treatment for PCH and patients rarely survive to adulthood (36). PCH is grouped into 11 subtypes based on phenotypic characteristics such as severe hypoplasia, trouble swallowing, progressive microcephaly, and motor and cognitive impairments (37). A mutation within CLP1 is linked to class PCH10 (34,38,39), while mutations in TSEN2, TSEN15, TSEN34, and TSEN54 are associated with PCH2, PCH4, and PCH5 (32,40).…”

Section: Introductionmentioning

confidence: 99%

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Reconstitution of the Human tRNA Splicing Endonuclease Complex: insight into the regulation of pre-tRNA cleavage

Hayne

Schmidt²,

Matera³

et al. 2019

Preprint

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The splicing of tRNA introns is a critical step in pre-tRNA maturation. In archaea and eukaryotes, tRNA intron removal is catalyzed by the tRNA splicing endonuclease (TSEN) complex. Eukaryotic TSEN is comprised of four core subunits (TSEN54, TSEN2, TSEN34, and TSEN15). The human TSEN complex additionally co-purifies with the polynucleotide kinase CLP1; however, CLP1's role in tRNA splicing remains unclear. Mutations in genes encoding all four TSEN subunits, as well as CLP1, are known to cause neurodegenerative disorders, yet the mechanisms underlying the pathogenesis of these disorders are unknown. Here, we developed a recombinant system that produces active TSEN complex. Co-expression of all four TSEN subunits is required for efficient formation and function of the complex. We show that human CLP1 associates with the active TSEN complex, but is not required for tRNA intron cleavage in vitro. Moreover, RNAi knockdown of the Drosophila CLP1 orthologue, cbc, promotes biogenesis of mature tRNAs and circularized tRNA introns (tricRNAs) in vivo. Collectively, these and other findings suggest that CLP1/cbc plays a regulatory role in tRNA splicing by serving as a negative modulator of the direct tRNA ligation pathway in animal cells.We thank Drs. Andrew Sikkema and Marcos Morgan as well as members of the Stanley Lab for their critical reading of this manuscript. We would like to acknowledge Robert Petrovich and the NIEHS Protein Expression Facility for assistance with protein expression in HEK293 suspension cultures and for supplying the anti-GFP resin. We also thank Robert Dutcher for his assistance with running SEC-MALS.

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Section: Introductionmentioning

confidence: 99%

“…The other PCH subtypes are linked to mutations in other genes, many of which are associated with RNA processing and maturation (37,(41)(42)(43). The underlying cause of PCH is unknown, but the association of PCH with several RNA processing enzymes suggests a link between disruption of RNA processing and neurological disorders.…”

Section: Introductionmentioning

confidence: 99%

Reconstitution of the Human tRNA Splicing Endonuclease Complex: insight into the regulation of pre-tRNA cleavage

Hayne

Schmidt²,

Matera³

et al. 2019

Preprint

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“…The majority of PCH cases have been linked to mutations in genes important for tRNA metabolism. In particular, 60% for all genetically defined cases of PCH are caused by mutations in the genes encoding for protein subunits of the TSEN complex (31,33,34,35,36). The main function accomplished by the TSEN complex is to produce mature and functional tRNAs by removing an intron.…”

Section: Biorxivmentioning

confidence: 99%

X-ray 3D imaging of gene expression in whole-mount murine brain by microCT, implication for functional analysis of tRNA endonuclease 54 gene mutated in pontocerebellar hypoplasia

Ermakova

Orsini

Fruscoloni

et al. 2019

Preprint

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Ermakova O et al.,BioRxiv 1 X-ray 3D imaging of gene expression in whole-mount murine brain by microCT, implication for functional analysis of tRNA endonuclease 54 gene mutated in pontocerebellar hypoplasia. AbstractAcquisition of detailed structural and molecular information from intact biological samples, while preserving cellular three-dimensional structures, still represents a challenge for biological studies aiming to unravel system functions.Here we describe a novel X-ray-based methodology for analysis of gene expression pattern in intact murine brain ex vivo by microCT. The method relays on detection of bromine molecules in the products of enzymatic reaction generated by the -galactosidase (lacZ) gene reporter. To demonstrate the feasibility of the method, the analysis of the expression pattern of tRNA endonuclease 54 (Tsen54)-lacZ reporter gene in the whole-mount murine brain in semi-quantitative manner is performed. Mutations in Tsen54 gene causes pontocerebellar hypoplasia (PCH), severe neurodegenerative disorder with both mental and motor deficits. Comparing relative levels of Tsen54 gene expression, we have demonstrated that highest Tsen54 expression observed in anatomical brain substructures important for the normal motor and memory functions in mice. In the forebrain strong expression in perirhinal, retrosplenial and secondary motor areas was observed. In olfactory area Tsen54 is highly expressed in the nucleus of the lateral olfactory tract, anterior olfactory and bed nuclei, while in hypothalamus in lateral mammillary nucleus and preoptic area. In hindbrain Tsen54 is expressed in the reticular, cuneate and trigeminal nuclei of medulla, and in pontine gray of pons and in cerebellum, in the molecular and Purkinje cell layers. Delineating anatomical brain regions in which Tsen54 is strongly expressed will allow functionally address the role Tsen54 gene in normal physiology and in PCH disease. Ermakova O et al., BioRxiv 3 Significance Statement.Characterization of gene expression pattern in the brain of model organisms is critical for unravelling the gene function in normal physiology and disease. It is performed by optical imaging of the two-dimensional brain sections which then assembled in volume images. Here we applied microCT platform, which allows three-dimensional imaging of non transparent samples, for analysis of gene expression. This method based on detection by X-ray the bromine molecules presented in the products generated by enzymatic activity of b-galactosidase reporter gene. With this method we identify anatomical brain substructures in which Tsen54 gene, mutated in pontocerebellar hypoplasia disease, is expressed.

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“…A number of missense mutations that cause single amino acid substitutions in conserved regions of EXOSC3 have been linked to PCH1b [6]. Of note, clinical reports indicate that the severity of PCH1b pathology is influenced by EXOSC3 allelic heterogeneity, suggesting a genotype-phenotype correlation [6,[21][22][23]. These observations indicate that EXOSC3 plays a critical role in the brain and suggest specific functional consequences for amino acid changes linked to disease.…”

Section: Introductionmentioning

confidence: 97%

ADrosophilaModel of Pontocerebellar Hypoplasia Reveals a Critical Role for the RNA Exosome in Neurons

Morton

Jalloh

Kim

et al. 2019

Preprint

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6Co-corresponding Authors Phone: 770-289-9986 (DJM) and Running title: Analysis of RNA exosome disease-linked substitutions in Drosophila EXOSC3 ortholog AbstractThe RNA exosome is an evolutionarily-conserved ribonuclease complex critically important for precise processing and/or complete degradation of a variety of cellular RNAs. The recent discovery that mutations in genes encoding structural RNA exosome subunits cause tissue-specific diseases makes defining the role of this complex within specific tissues critically important. Mutations in the RNA exosome component 3 (EXOSC3) gene cause Pontocerebellar Hypoplasia Type 1b (PCH1b), an autosomal recessive neurologic disorder. The majority of disease-linked mutations are missense mutations that alter evolutionarily-conserved regions of EXOSC3. The tissue-specific defects caused by these amino acid changes in EXOSC3 are challenging to understand based on current models of RNA exosome function with only limited analysis of the complex in any multicellular model in vivo. The goal of this study is to provide insight into how mutations in EXOSC3 impact the function of the RNA exosome. To assess the tissue-specific roles and requirements for the Drosophila ortholog of EXOSC3 termed Rrp40, we utilized tissue-specific RNAi drivers. Depletion of Rrp40 in different tissues reveals a general requirement for Rrp40 in the development of many tissues including the brain, but also highlight an agedependent requirement for Rrp40 in neurons. To assess the functional consequences of the specific amino acid substitutions in EXOSC3 that cause PCH1b, we used CRISPR/Cas9 gene editing technology to generate flies that model this RNA exosome-linked disease. These flies show reduced viability; however, the surviving animals exhibit a spectrum of behavioral and morphological phenotypes. RNA-seq analysis of these Drosophila Rrp40 mutants reveals increases in the steady-state levels of specific mRNAs and ncRNAs, some of which are central to neuronal function. In particular, Arc1 mRNA, which encodes a key regulator of synaptic plasticity, is increased in the Drosophila Rrp40 mutants. Taken together, this study defines a requirement for the RNA exosome in specific tissues/cell types and provides insight into how defects in RNA exosome function caused by specific amino acid substitutions that occur in PCH1b can contribute to neuronal dysfunction. Morton et al. 3 Author SummaryPontocerebellar Hypoplasia Type 1b (PCH1b) is a devastating genetic neurological disorder that preferentially affects specific regions of the brain. Typically, children born with PCH1b have structural defects in regions of the brain including those associated with key autonomic functions. Currently, there is no cure or treatment for the disease. PCH1b is caused by mutations in the RNA exosome component 3 (EXOSC3) gene, which encodes a structural component of the ubiquitous and essential multi-subunit RNA exosome complex.The RNA exosome is critical for both precise processing and turnover of multiple classes of RNAs. To el...

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What’s new in pontocerebellar hypoplasia? An update on genes and subtypes

Cited by 126 publications

References 111 publications

Reconstitution of the Human tRNA Splicing Endonuclease Complex: insight into the regulation of pre-tRNA cleavage

Reconstitution of the Human tRNA Splicing Endonuclease Complex: insight into the regulation of pre-tRNA cleavage

X-ray 3D imaging of gene expression in whole-mount murine brain by microCT, implication for functional analysis of tRNA endonuclease 54 gene mutated in pontocerebellar hypoplasia

ADrosophilaModel of Pontocerebellar Hypoplasia Reveals a Critical Role for the RNA Exosome in Neurons

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