Similar Datasets
Project description:De novo germline histone H3.3 amino acid substitutions, including H3.3G34R/V, cause severe neurodevelopmental syndromes. To understand how these mutations impact brain development, we generated heterozygous H3.3G34R/V/W direct knock-in mutant mice and identified strikingly distinct developmental defects for each amino acid substitution. H3.3G34R-mutant mice uniquely exhibited progressive microcephaly and neurodegeneration, associated with abnormal accumulation of damage-associated microglia and astrocytes, and concurrent neuronal depletion in postnatal brains. On the mutant H3.3 tail, G34R severely decreased H3K36me2, impairing recruitment of DNA methyltransferase DNMT3A and promoting its redistribution on chromatin. This results in loss of CH methylation at complement and other innate immune genes promoting their sustained expression, and, aberrant CG methylation at neuronal gene promoters and undue silencing. Persistent complement expression in G34R neurons led to excessive synaptic pruning, neuroinflammation, and neuronal damage accounting for progressive neurodegeneration. Our study reveals H3.3G34-substitutions have differential impact on chromatin, which underlie the diverse phenotypes observed. Notably, we uncover unappreciated roles for H3K36me2 and DNMT3A-dependent CH-methylation in modulating pruning and neuroinflammation in post-natal brains.
2023-03-16 | GSE199883 | GEO
Project description:Germline histone H3.3 amino acid substitutions, including H3.3G34R/V, cause severe neurodevelopmental syndromes. To understand how these mutations impact brain development, we generated H3.3G34R/V/W knock-in mice and identified strikingly distinct developmental defects for each mutation. H3.3G34R-mutants uniquely exhibited progressive microcephaly and neurodegeneration, with abnormal accumulation of disease-associated microglia and concurrent neuronal depletion. G34R severely decreased H3K36me2 on the mutant H3.3 tail, impairing recruitment of DNA methyltransferase DNMT3A. Redistribution of DNMT3A on chromatin promoted sustained expression of complement and other innate immune genes through loss of non-CG (CH) methylation, and silencing of neuronal gene promoters through aberrant CG methylation. Persistent complement expression in G34R neurons led to neuroinflammation possibly accounting for progressive neurodegeneration. Our study reveals that H3.3G34-substitutions have differential impact on the epigenome, which underlie the diverse phenotypes observed, and uncovers unappreciated roles for H3K36me2 and DNMT3A-dependent CH-methylation in modulating synaptic pruning and neuroinflammation in post-natal brains.
2023-03-16 | GSE211387 | GEO
Project description:De novo germline histone H3.3 amino acid substitutions, including H3.3G34R/V, cause severe neurodevelopmental syndromes. To understand how these mutations impact brain development, we generated heterozygous H3.3G34R/V/W direct knock-in mutant mice and identified strikingly distinct developmental defects for each amino acid substitution. H3.3G34R-mutant mice uniquely exhibited progressive microcephaly and neurodegeneration, associated with abnormal accumulation of damage-associated microglia and astrocytes, and concurrent neuronal depletion in postnatal brains. On the mutant H3.3 tail, G34R severely decreased H3K36me2, impairing recruitment of DNA methyltransferase DNMT3A and promoting its redistribution on chromatin. This results in loss of CH methylation at complement and other innate immune genes promoting their sustained expression, and, aberrant CG methylation at neuronal gene promoters and undue silencing. Persistent complement expression in G34R neurons led to excessive synaptic pruning, neuroinflammation, and neuronal damage accounting for progressive neurodegeneration. Our study reveals H3.3G34-substitutions have differential impact on chromatin, which underlie the diverse phenotypes observed. Notably, we uncover unappreciated roles for H3K36me2 and DNMT3A-dependent CH-methylation in modulating pruning and neuroinflammation in post-natal brains.
2023-03-16 | GSE199884 | GEO
Project description:De novo germline histone H3.3 amino acid substitutions, including H3.3G34R/V, cause severe neurodevelopmental syndromes. To understand how these mutations impact brain development, we generated heterozygous H3.3G34R/V/W direct knock-in mutant mice and identified strikingly distinct developmental defects for each amino acid substitution. H3.3G34R-mutant mice uniquely exhibited progressive microcephaly and neurodegeneration, associated with abnormal accumulation of damage-associated microglia and astrocytes, and concurrent neuronal depletion in postnatal brains. On the mutant H3.3 tail, G34R severely decreased H3K36me2, impairing recruitment of DNA methyltransferase DNMT3A and promoting its redistribution on chromatin. This results in loss of CH methylation at complement and other innate immune genes promoting their sustained expression, and, aberrant CG methylation at neuronal gene promoters and undue silencing. Persistent complement expression in G34R neurons led to excessive synaptic pruning, neuroinflammation, and neuronal damage accounting for progressive neurodegeneration. Our study reveals H3.3G34-substitutions have differential impact on chromatin, which underlie the diverse phenotypes observed. Notably, we uncover unappreciated roles for H3K36me2 and DNMT3A-dependent CH-methylation in modulating pruning and neuroinflammation in post-natal brains.
2023-03-16 | GSE199882 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2018-12-10 | GSE103008 | GEO
Project description:Blood pressure regulation is crucial for the maintenance of health, and hypertension is a risk factor for myocardial infarction, heart failure, stroke and renal disease. Nitric oxide (NO) and prostacyclin trigger well-defined vasodilator pathways; however, substantial vasorelaxation in response to agents such as acetylcholine persists when the synthesis of these molecules is prevented. This remaining vasorelaxation activity, termed endothelium-derived hyperpolarizing factor (EDHF), is more prevalent in resistance than in conduit blood vessels and is considered a major mechanism for blood pressure control. Hydrogen peroxide (H2O2) has been shown to be a major component of EDHF in several vascular beds in multiple species, including in humans. H2O2 causes the formation of a disulfide bond between the two ? subunits of protein kinase G I-? (PKGI-?), which activates the kinase independently of the NO-cyclic guanosine monophosphate (cGMP) pathway and is coupled to vasodilation. To test the importance of PKGI-? oxidation in the EDHF mechanism and blood pressure control in vivo, we generated a knock-in mouse expressing only a C42S 'redox-dead' version of PKGI-?. This amino acid substitution, a single-atom change (an oxygen atom replacing a sulfur atom), blocked the vasodilatory action of H2O2 on resistance vessels and resulted in hypertension in vivo.
| S-EPMC3276848 | biostudies-literature
Project description:The DNA methyltransferase DNMT3A R882H mutation is observed in 25% of all AML patients. DNMT3A is active as tetramer and the R882H mutation is located in one of the subunit/subunit interfaces. Previous work has reported that formation of mixed wildtype/R882H complexes leads to a strong loss of catalytic activity observed in in vitro DNA methylation assays (Russler-Germain et al., 2014, Cancer Cell 25:442-454). To investigate this effect further, we have prepared mixed wildtype/R882H DNMT3A complexes by incubation of individually purified subunits of the DNMT3A catalytic domain and full-length DNMT3A2. In addition, we have used a double affinity tag approach and specifically purified mixed catalytic domain complexes formed after co-expression of R882H and wildtype subunits in E. coli cells. Afterwards, we determined the catalytic activity of the mixed complexes and compared it to that of purified complexes only consisting of one subunit type. In both settings, the expected catalytic activities of mixed R882H/wildtype complexes were observed demonstrating an absence of a dominant negative effect of the R882H mutation in purified DNMT3A enzymes. This result suggests that heterocomplex formation of DNMT3A and R882H is unlikely to cause dominant negative effects in human cells as well. The limitations of this conclusion and its implications are discussed.
| S-EPMC6125428 | biostudies-literature
Project description:Hereditary retinal degenerative diseases, such as retinitis pigmentosa (RP), are characterized by the progressive loss of rod photoreceptors followed by loss of cones. While retinal gene therapy clinical trials demonstrated temporary improvement in visual function, this approach has yet to achieve sustained functional and anatomical rescue after disease onset in patients. The lack of sustained benefit could be due to insufficient transduction efficiency of viral vectors ("too little") and/or because the disease is too advanced ("too late") at the time therapy is initiated. Here, we tested the latter hypothesis and developed a mouse RP model that permits restoration of the mutant gene in all diseased photoreceptor cells, thereby ensuring sufficient transduction efficiency. We then treated mice at early, mid, or late disease stages. At all 3 time points, degeneration was halted and function was rescued for at least 1 year. Not only do our results demonstrate that gene therapy effectively preserves function after the onset of degeneration, our study also demonstrates that there is a broad therapeutic time window. Moreover, these results suggest that RP patients are treatable, despite most being diagnosed after substantial photoreceptor loss, and that gene therapy research must focus on improving transduction efficiency to maximize clinical impact.
| S-EPMC4588299 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2018-11-26 | GSE120558 | GEO
Project description:LonP1 is crucial for maintaining mitochondrial proteostasis and mitigating cell stress. We identified a novel homozygous missense LONP1 variant, c.2282 C > T, (p.Pro761Leu), by whole-exome and Sanger sequencing in two siblings born to healthy consanguineous parents. Both siblings presented with stepwise regression during infancy, profound hypotonia and muscle weakness, severe intellectual disability and progressive cerebellar atrophy on brain imaging. Muscle biopsy revealed the absence of ragged-red fibers, however, scattered cytochrome c oxidase-negative staining and electron dense mitochondrial inclusions were observed. Primary cultured fibroblasts from the siblings showed normal levels of mtDNA and mitochondrial transcripts, and normal activities of oxidative phosphorylation complexes I through V. Interestingly, fibroblasts of both siblings showed glucose-repressed oxygen consumption compared to their mother, whereas galactose and palmitic acid utilization were similar. Notably, the siblings' fibroblasts had reduced pyruvate dehydrogenase (PDH) activity and elevated intracellular lactate:pyruvate ratios, whereas plasma ratios were normal. We demonstrated that in the siblings' fibroblasts, PDH dysfunction was caused by increased levels of the phosphorylated E1? subunit of PDH, which inhibits enzyme activity. Blocking E1? phosphorylation activated PDH and reduced intracellular lactate concentrations. In addition, overexpressing wild-type LonP1 in the siblings' fibroblasts down-regulated phosphoE1?. Furthermore, in vitro studies demonstrated that purified LonP1-P761L failed to degrade phosphorylated E1?, in contrast to wild-type LonP1. We propose a novel mechanism whereby homozygous expression of the LonP1-P761L variant leads to PDH deficiency and energy metabolism dysfunction, which promotes severe neurologic impairment and neurodegeneration.
| S-EPMC6322071 | biostudies-literature