RESUMO
Loss-of-function mutations in the GNAL gene are responsible for DYT-GNAL dystonia. However, how GNAL mutations contribute to synaptic dysfunction is still unclear. The GNAL gene encodes the Gαolf protein, an isoform of stimulatory Gαs enriched in the striatum, with a key role in the regulation of cAMP signaling. Here, we used a combined biochemical and electrophysiological approach to study GPCR-mediated AC-cAMP cascade in the striatum of the heterozygous GNAL (GNAL+/-) rat model. We first analyzed adenosine type 2 (A2AR), and dopamine type 1 (D1R) receptors, which are directly coupled to Gαolf, and observed that the total levels of A2AR were increased, whereas D1R level was unaltered in GNAL+/- rats. In addition, the striatal isoform of adenylyl cyclase (AC5) was reduced, despite unaltered basal cAMP levels. Notably, the protein expression level of dopamine type 2 receptor (D2R), that inhibits the AC5-cAMP signaling pathway, was also reduced, similar to what observed in different DYT-TOR1A dystonia models. Accordingly, in the GNAL+/- rat striatum we found altered levels of the D2R regulatory proteins, RGS9-2, spinophilin, Gß5 and ß-arrestin2, suggesting a downregulation of D2R signaling cascade. Additionally, by analyzing the responses of striatal cholinergic interneurons to D2R activation, we found that the receptor-mediated inhibitory effect is significantly attenuated in GNAL+/- interneurons. Altogether, our findings demonstrate a profound alteration in the A2AR/D2R-AC-cAMP cascade in the striatum of the rat DYT-GNAL dystonia model, and provide a plausible explanation for our previous findings on the loss of dopamine D2R-dependent corticostriatal long-term depression.
Assuntos
Distonia , Distúrbios Distônicos , Ratos , Animais , Adenilil Ciclases/genética , Adenilil Ciclases/metabolismo , Dopamina/metabolismo , AMP Cíclico/metabolismo , Distonia/genética , Transdução de Sinais/fisiologia , Corpo Estriado/metabolismo , Receptores Dopaminérgicos/metabolismo , Isoformas de Proteínas/metabolismoRESUMO
Polyglutamine (polyQ)-encoding CAG repeat expansions represent a common disease-causing mutation responsible for several dominant spinocerebellar ataxias (SCAs). PolyQ-expanded SCA proteins are toxic for cerebellar neurons, with Purkinje cells (PCs) being the most vulnerable. RNA interference (RNAi) reagents targeting transcripts with expanded CAG reduce the level of various mutant SCA proteins in an allele-selective manner in vitro and represent promising universal tools for treating multiple CAG/polyQ SCAs. However, it remains unclear whether the therapeutic targeting of CAG expansion can be achieved in vivo and if it can ameliorate cerebellar functions. Here, using a mouse model of SCA7 expressing a mutant Atxn7 allele with 140 CAGs, we examined the efficacy of short hairpin RNAs (shRNAs) targeting CAG repeats expressed from PHP.eB adeno-associated virus vectors (AAVs), which were introduced into the brain via intravascular injection. We demonstrated that shRNAs carrying various mismatches with the CAG target sequence reduced the level of polyQ-expanded ATXN7 in the cerebellum, albeit with varying degrees of allele selectivity and safety profile. An shRNA named A4 potently reduced the level of polyQ-expanded ATXN7, with no effect on normal ATXN7 levels and no adverse side effects. Furthermore, A4 shRNA treatment improved a range of motor and behavioral parameters 23 weeks after AAV injection and attenuated the disease burden of PCs by preventing the downregulation of several PC-type-specific genes. Our results show the feasibility of the selective targeting of CAG expansion in the cerebellum using a blood-brain barrier-permeable vector to attenuate the disease phenotype in an SCA mouse model. Our study represents a significant advancement in developing CAG-targeting strategies as a potential therapy for SCA7 and possibly other CAG/polyQ SCAs.
Assuntos
Ataxina-7 , Dependovirus , Modelos Animais de Doenças , Peptídeos , Fenótipo , RNA Interferente Pequeno , Ataxias Espinocerebelares , Expansão das Repetições de Trinucleotídeos , Animais , Ataxias Espinocerebelares/genética , Ataxias Espinocerebelares/terapia , Ataxias Espinocerebelares/metabolismo , Peptídeos/genética , Dependovirus/genética , Camundongos , Ataxina-7/genética , Ataxina-7/metabolismo , Expansão das Repetições de Trinucleotídeos/genética , RNA Interferente Pequeno/genética , Vetores Genéticos/genética , Vetores Genéticos/administração & dosagem , Células de Purkinje/metabolismo , Células de Purkinje/patologia , Camundongos Transgênicos , Cerebelo/metabolismo , Cerebelo/patologia , Humanos , Terapia Genética/métodos , AlelosRESUMO
Duchenne muscular dystrophy (DMD) is a severe progressive muscle disease that mainly affects boys due to X-linked recessive inheritance. In most affected individuals, MLPA or sequencing-based techniques detect deletions, duplications, or point mutations in the dystrophin-encoding DMD gene. However, in a small subset of patients clinically diagnosed with DMD, the molecular cause is not identified with these routine methods. Evaluation of the 60 DMD patients in our center revealed three cases without a known genetic cause. DNA samples of these patients were analyzed using whole-exome sequencing (WES) and, if unconclusive, optical genome mapping (OGM). WES led to a diagnosis in two cases: one patient was found to carry a splice mutation in the DMD gene that had not been identified during previous Sanger sequencing. In the second patient, we detected two variants in the fukutin gene (FKTN) that were presumed to be disease-causing. In the third patient, WES was unremarkable, but OGM identified an inversion disrupting the DMD gene (~1.28 Mb) that was subsequently confirmed with long-read sequencing. These results highlight the importance of reanalyzing unsolved cases using WES and demonstrate that OGM is a useful method for identifying large structural variants in cases with unremarkable exome sequencing.
Assuntos
Distrofia Muscular de Duchenne , Humanos , Masculino , Inversão Cromossômica , Mapeamento Cromossômico , Distrofina/genética , Sequenciamento do Exoma , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/genética , MutaçãoRESUMO
Spinocerebellar ataxia type 7 (SCA7) is an inherited neurodegenerative disease mainly characterized by motor incoordination because of progressive cerebellar degeneration. SCA7 is caused by polyglutamine expansion in ATXN7, a subunit of the transcriptional coactivator SAGA, which harbors histone modification activities. Polyglutamine expansions in specific proteins are also responsible for SCA1-SCA3, SCA6, and SCA17; however, the converging and diverging pathomechanisms remain poorly understood. Using a new SCA7 knock-in mouse, SCA7140Q/5Q, we analyzed gene expression in the cerebellum and assigned gene deregulation to specific cell types using published datasets. Gene deregulation affects all cerebellar cell types, although at variable degree, and correlates with alterations of SAGA-dependent epigenetic marks. Purkinje cells (PCs) are by far the most affected neurons and show reduced expression of 83 cell-type identity genes, including these critical for their spontaneous firing activity and synaptic functions. PC gene downregulation precedes morphologic alterations, pacemaker dysfunction, and motor incoordination. Strikingly, most PC genes downregulated in SCA7 have also decreased expression in SCA1 and SCA2 mice, revealing converging pathomechanisms and a common disease signature involving cGMP-PKG and phosphatidylinositol signaling pathways and LTD. Our study thus points out molecular targets for therapeutic development, which may prove beneficial for several SCAs. Furthermore, we show that SCA7140Q/5Q males and females exhibit the major disease features observed in patients, including cerebellar damage, cerebral atrophy, peripheral nerves pathology, and photoreceptor dystrophy, which account for progressive impairment of behavior, motor, and visual functions. SCA7140Q/5Q mice represent an accurate model for the investigation of different aspects of SCA7 pathogenesis.SIGNIFICANCE STATEMENT Spinocerebellar ataxia 7 (SCA7) is one of the several forms of inherited SCAs characterized by cerebellar degeneration because of polyglutamine expansion in specific proteins. The ATXN7 involved in SCA7 is a subunit of SAGA transcriptional coactivator complex. To understand the pathomechanisms of SCA7, we determined the cell type-specific gene deregulation in SCA7 mouse cerebellum. We found that the Purkinje cells are the most affected cerebellar cell type and show downregulation of a large subset of neuronal identity genes, critical for their spontaneous firing and synaptic functions. Strikingly, the same Purkinje cell genes are downregulated in mouse models of two other SCAs. Thus, our work reveals a disease signature shared among several SCAs and uncovers potential molecular targets for their treatment.
Assuntos
Cerebelo/patologia , Células de Purkinje/patologia , Ataxias Espinocerebelares/patologia , Animais , Regulação para Baixo , Feminino , Técnicas de Introdução de Genes , Masculino , Camundongos , TranscriptomaRESUMO
Huntington's disease (HD), a congenital neurodegenerative disorder, extends its pathological damages beyond the nervous system. The systematic manifestation of HD has been extensively described in numerous studies, including dysfunction in peripheral organs and peripheral inflammation. Gut dysbiosis and the gut-liver-brain axis have garnered greater emphasis in neurodegenerative research, and increased plasma levels of pro-inflammatory cytokines have been identified in HD patients and various in vivo models, correlating with disease progression. In the present study, we investigated hepatic pathological markers in the liver of R6/2 mice which convey exon 1 of the human mutant huntingtin gene. Furthermore, we evaluated the impact of intravenously administered Mesenchymal Stromal Cells (MSCs) on the liver enzymes, changes in hepatic inflammatory markers, as well as brain pathology and behavioral deficits in R6/2 mice. Our results revealed altered enzyme expression and increased levels of inflammatory mediators in the liver of R6/2 mice, which were significantly attenuated in the MSC-treated R6/2 mice. Remarkably, neuronal pathology and altered motor activities in the MSC-treated R6/2 mice were significantly ameliorated, despite the absence of MSCs in the postmortem brain. Our data highlight the importance of hepatic pathological changes in HD, providing a potential therapeutic approach. Moreover, the data open new perspectives for the search in blood biomarkers correlating with liver pathology in HD.
Assuntos
Doença de Huntington , Camundongos , Humanos , Animais , Doença de Huntington/metabolismo , Camundongos Transgênicos , Modelos Animais de Doenças , Encéfalo/metabolismo , Fígado/metabolismoRESUMO
While balanced reciprocal translocations are relatively common, they often remain clinically silent unless they lead to the disruption of functional genes. In this study, we present the case of a boy exhibiting developmental delay and mild intellectual disability. Initial karyotyping revealed a translocation t(5;6)(q13;q23) between chromosomes 5 and 6 with limited resolution. Optical genome mapping (OGM) enabled a more precise depiction of the breakpoint regions involved in the reciprocal translocation. While the breakpoint region on chromosome 6 did not encompass any known gene, OGM revealed the disruption of the RASGRF2 (Ras protein-specific guanine nucleotide releasing factor 2) gene on chromosome 5, implicating RASGRF2 as a potential candidate gene contributing to the observed developmental delay in the patient. Variations in RASGRF2 have so far not been reported in developmental delay, but research on the RASGRF2 gene underscores its significance in various aspects of neurodevelopment, including synaptic plasticity, signaling pathways, and behavioral responses. This study highlights the utility of OGM in identifying breakpoint regions, providing possible insights into the understanding of neurodevelopmental disorders. It also helps affected individuals in gaining more knowledge about potential causes of their conditions.
Assuntos
Deficiências do Desenvolvimento , Translocação Genética , Humanos , Masculino , Deficiências do Desenvolvimento/genética , Deficiências do Desenvolvimento/patologia , Fatores ras de Troca de Nucleotídeo Guanina/genética , Mapeamento Cromossômico , Cromossomos Humanos Par 5/genética , Deficiência Intelectual/genética , Deficiência Intelectual/patologiaRESUMO
Individuals with ultrarare disorders pose a structural challenge for healthcare systems since expert clinical knowledge is required to establish diagnoses. In TRANSLATE NAMSE, a 3-year prospective study, we evaluated a novel diagnostic concept based on multidisciplinary expertise in Germany. Here we present the systematic investigation of the phenotypic and molecular genetic data of 1,577 patients who had undergone exome sequencing and were partially analyzed with next-generation phenotyping approaches. Molecular genetic diagnoses were established in 32% of the patients totaling 370 distinct molecular genetic causes, most with prevalence below 1:50,000. During the diagnostic process, 34 novel and 23 candidate genotype-phenotype associations were identified, mainly in individuals with neurodevelopmental disorders. Sequencing data of the subcohort that consented to computer-assisted analysis of their facial images with GestaltMatcher could be prioritized more efficiently compared with approaches based solely on clinical features and molecular scores. Our study demonstrates the synergy of using next-generation sequencing and phenotyping for diagnosing ultrarare diseases in routine healthcare and discovering novel etiologies by multidisciplinary teams.
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala , Fenótipo , Humanos , Feminino , Masculino , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Criança , Alemanha , Sequenciamento do Exoma/métodos , Adolescente , Estudos de Associação Genética/métodos , Testes Genéticos/métodos , Pré-Escolar , Estudos Prospectivos , Adulto , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/diagnóstico , Lactente , Adulto JovemRESUMO
New techniques in molecular genetic diagnostics now allow for accurate diagnosis in a large proportion of patients with muscular diseases. Nevertheless, many patients remain unsolved, although the clinical history and/or the muscle biopsy give a clear indication of the involved genes. In many cases, there is a strong suspicion that the cause must lie in unexplored gene areas, such as deep-intronic or other non-coding regions. In order to find these changes, next-generation sequencing (NGS) methods are constantly evolving, making it possible to sequence entire genomes to reveal these previously uninvestigated regions. Here, we present a young woman who was strongly suspected of having a so far genetically unsolved sarcoglycanopathy based on her clinical history and muscle biopsy. Using short read whole genome sequencing (WGS), a homozygous inversion on chromosome 13 involving SGCG and LINC00621 was detected. The breakpoint in intron 2 of SGCG led to the absence of γ-sarcoglycan, resulting in the manifestation of autosomal recessive limb-girdle muscular dystrophy 5 (LGMDR5) in the young woman.
Assuntos
Distrofia Muscular do Cíngulo dos Membros , Sarcoglicanas , Humanos , Feminino , Sarcoglicanas/genética , Cromossomos Humanos Par 13 , Distrofia Muscular do Cíngulo dos Membros/diagnóstico , Distrofia Muscular do Cíngulo dos Membros/genética , Homozigoto , Sequenciamento Completo do GenomaRESUMO
In acute myeloid leukemia (AML), treatment decisions are currently made according to the risk classification of the European LeukemiaNet (ELN), which is based on genetic alterations. Recently, optical genome mapping (OGM) as a novel method proved to yield a genome-wide and detailed cytogenetic characterization at the time of diagnosis. A young female patient suffered from a rather unexpected aggressive disease course under FLT3 targeted therapy in combination with induction chemotherapy. By applying a "next-generation diagnostic workup" strategy with OGM and whole-exome sequencing (WES), a DDX3X: MLLT10 gene fusion could be detected, otherwise missed by routine diagnostics. Furthermore, several aspects of lineage ambiguity not shown by standard diagnostics were unraveled such as deletions of SUZ12 and ARPP21, as well as T-cell receptor recombination. In summary, the detection of this particular gene fusion DDX3X: MLLT10 in a female AML patient and the findings of lineage ambiguity are potential explanations for the aggressive course of disease. Our study demonstrates that OGM can yield novel clinically significant results, including additional information helpful in disease monitoring and disease biology.
RESUMO
Intrastriatal administration of mesenchymal stem cells (MSCs) has shown beneficial effects in rodent models of Huntington disease (HD). However, the invasive nature of surgical procedure and its potential to trigger the host immune response may limit its clinical use. Hence, we sought to evaluate the non-invasive intranasal administration (INA) of MSC delivery as an effective alternative route in HD. GFP-expressing MSCs derived from bone marrow were intranasally administered to 4-week-old R6/2 HD transgenic mice. MSCs were detected in the olfactory bulb, midbrain and striatum five days post-delivery. Compared to phosphate-buffered saline (PBS)-treated littermates, MSC-treated R6/2 mice showed an increased survival rate and attenuated circadian activity disruption assessed by locomotor activity. MSCs increased the protein expression of DARPP-32 and tyrosine hydroxylase (TH) and downregulated gene expression of inflammatory modulators in the brain 7.5 weeks after INA. While vehicle treated R6/2 mice displayed decreased Iba1 expression and altered microglial morphology in comparison to the wild type littermates, MSCs restored both, Iba1 level and the thickness of microglial processes in the striatum of R6/2 mice. Our results demonstrate significantly ameliorated phenotypes of R6/2 mice after MSCs administration via INA, suggesting this method as an effective delivering route of cells to the brain for HD therapy.
Assuntos
Dopamina/metabolismo , Doença de Huntington/fisiopatologia , Doença de Huntington/terapia , Inflamação/patologia , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Transmissão Sináptica , Administração Intranasal , Animais , Encéfalo/patologia , Encéfalo/fisiopatologia , Rastreamento de Células , Ritmo Circadiano , Modelos Animais de Doenças , Fosfoproteína 32 Regulada por cAMP e Dopamina/metabolismo , Regulação da Expressão Gênica , Humanos , Doença de Huntington/genética , Inflamação/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/metabolismo , Microglia/patologia , Atividade Motora , Fatores de Crescimento Neural/metabolismo , Sono , Análise de Sobrevida , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Huntington disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by a CAG repeat expansion in the gene coding for the huntingtin protein (HTT). Mutant HTT (mHTT) has been proposed to cause neuronal dysfunction and neuronal loss through multiple mechanisms. Transcriptional changes may be a core pathogenic feature of HD. Utilizing the Affymetrix platform we performed a genome-wide RNA expression analysis in two BACHD transgenic rat lines (TG5 and TG9) at 12 months of age, both of which carry full-length human mHTT but with different expression levels. By defining the threshold of significance at p < 0.01, we found 1608 genes and 871 genes differentially expressed in both TG5 and TG9 rats when compared to the wild type littermates, respectively. We only chose the highly up-/down-regulated genes for further analysis by setting an additional threshold of 1.5 fold change. Comparing gene expression profiles of human HD brains and BACHD rats revealed a high concordance in both functional and IPA (Ingenuity Pathway Analysis) canonical pathways relevant to HD. In addition, we investigated the causes leading to gene expression changes at molecular and protein levels in BACHD rats including the involvement of polyQ-containing transcription factors TATA box-binding protein (TBP), Sp1 and CBP as well as the chromatin structure. We demonstrate that the BACHD rat model recapitulates the gene expression changes of the human disease supporting its role as a preclinical research animal model. We also show for the first time that TFIID complex formation is reduced, while soluble TBP is increased in an HD model. This finding suggests that mHTT is a competitor instead of a recruiter of polyQ-containing transcription factors in the transcription process in HD.