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Biology subjects

Alisch, R. S.

Publications and source records attributed to Alisch, R. S..

8 recordsLinked to original sources

A Multi-Omics Atlas of Naturally Occurring Myelomeningocele in a Large-Animal Model Reveals Heritable Architecture.

Neural tube closure relies on tightly coordinated morphogenetic programs integrating convergent extension, apical constriction of the neuroepithelium, and precise cell-cell interactions across germ layers. Disruption of these processes results in myelomeningocele, a severe complex congenital defect with lifelong multisystem consequences whose genetic and epigenetic determinants remain poorly defined. Using a sheep population with naturally occurring myelomeningocele, we quantified substantial heritability (0.42-0.68) and generated the first integrated multi-omics, multi-tissue atlas of this condition in any mammalian species. Genetic, transcriptomic, and whole-genome DNA methylation profiling across ectoderm- and mesoderm-derived tissues revealed shared and lineage-specific perturbations converging on cell-adhesion, cytoskeletal, migratory, inflammatory, and folate-responsive pathways. Chromosome 24 emerged as a multi-omics hotspot enriched for differentially expressed genes, differentially methylated regions, and candidate regulatory loci of GWAS signals, overlapping with human neurological and embryonic development trajectories. Cross-tissue network analyses highlighted coordinated disruption of neurulation-critical gene modules, establishing sheep as a robust translational model for mechanistic dissection of neural tube defect biology.

genetics↗

Epigenetic genes are differentially methylated in the blood of persons with mild cognitive impairment and Alzheimers disease

BackgroundEnvironmental factors play a role in AD pathology and are mediated by changes in DNA methylation levels. Methods and ResultsWe investigated whole genome methylation sequencing (WGMS) data from the blood of participants with mild cognitive impairment (MCI, N=99), late onset dementia due to Alzheimers disease (AD, N=109), and who are cognitively unimpaired (CU, N=174) to test for differential methylation in 812 genes with roles in epigenetic regulation (e.g., DNA methylation and demethylation, chromatin remodeling, histone modification, and RNA modification) curated from the EpiFactors 2.1 database. 71/812 genes were differentially methylated comprising 190 unique differentially methylated positions (DMPs) in MCI (MCI vs. CU pairwise comparison). 60/812 genes were differentially methylated comprising 220 DMPs in AD (AD vs. CU pairwise comparison). The majority of differentially methylated genes in both MCI (41/71) and AD (33/60) were histone modification genes and 23 differentially methylated genes were shared in both pairwise comparisons. 96 genes were differentially methylated comprising 243 DMPs between persons with MCI and AD (AD vs. MCI pairwise comparison). 10 differentially methylated genes were shared between the 3 pairwise comparisons, including CUGBP elav-like family member 2 (CELF2), histone deacetylase 9 (HDAC9), RNA binding fox-1 homolog 1 (RBFOX1), TATA-box binding protein associated factor 4 (TAF4), and thymine DNA glycosylase (TDG). ConclusionGenes that participate in the epigenetic regulation of gene expression, particularly histone modifications, are differentially methylated in blood between persons with and without MCI and AD, warranting further elucidation of their role in the molecular pathogenesis of cognitive decline.

genomics↗

Differential DNA methylation in blood in nuclear genes that encode mitochondrial proteins in mild cognitive impairment and Alzheimers disease

BackgroundAltered mitochondrial function contributes to the pathogenesis of mild cognitive impairment (MCI) and late-onset dementia due to Alzheimers disease (AD). ObjectiveTo test for differential methylation in nuclear genes that encode proteins that participate in mitochondrial function between cognitively unimpaired participants (CU) and those with MCI and AD. MethodsRecently published whole genome methylation sequencing (WGMS) in blood from CU participants (N=174), and those with MCI (N=99) and AD (N=109) was used to test for differential methylation in 1,121 nuclear genes that encode proteins that participate in mitochondrial function in the Human Protein Atlas. ResultsSeventy-four nuclear genes that encode proteins that participate in mitochondrial function were differentially methylated between persons with MCI and CU. Seventy-one genes were differentially methylated between persons with AD and CU, and 132 genes were differentially methylated between persons with MCI and AD. Thirteen differentially methylated genes shared between the 3 comparisons support contributions from disrupted metabolism and oxidative stress pathways in AD pathogenesis. ConclusionsNuclear genes that encode proteins that participate in mitochondrial glucose metabolism, fatty acid metabolism and oxidative stress pathways are differentially methylated between persons who are CU and those with MCI and AD.

genomics↗

Sex-Specific Differential DNA Methylation in Mild Cognitive Impairment and Alzheimers Disease

Sex differences in late-onset Alzheimers disease (AD) progression include accelerated decrements in cognitive status and greater amyloid and tau biomarker burdens in females. To identify sex-specific differentially methylated positions (DMPs) and genes in persons with mild cognitive impairment (MCI) and AD, we analyzed whole genome methylation sequencing on blood samples from participants with MCI (N=99, 52% female), AD (N=109, 43% female), and those cognitively unimpaired (CU; N=174, 52% female). Ninety-four percent of DMPs from MCI vs. CU, AD vs. CU, and AD vs. MCI pairwise comparisons were sex-specific. Female-specific DMPs were enriched in neurologic gene sets (e.g., synaptic membrane, ion channel complex), while male-specific DMPs showed limited enrichment. Sex-specific DMPs overlapped blood-specific enhancers, promoters, and transcription factor binding motifs, highlighting divergent epigenetic regulation by sex. These findings identify sex-specific genes and molecular pathways in MCI and AD and support that blood DNA methylation levels can distinguish cognitive status.

genomics↗

Telomere length and cognitive function among middle-aged and older participants from communities underrepresented in aging research: A preliminary study

ObjectiveAccelerated biological aging is a plausible and modifiable determinant of dementia burden facing minoritized communities, but is not well-studied in these historically underrepresented populations. Our objective was to preliminarily characterize relationships between telomere length and cognitive health among American Indian/Alaska Native (AI/AN) and Black/African American (B/AA) middle-aged and older adults. MethodsThis study included data on telomere length and cognitive test performance from 187 participants, enrolled in one of two community-based cognitive aging cohorts and who identified their primary race as AI/AN or B/AA. ResultsNested multivariable regression models revealed preliminary evidence for associations between telomere length and cognitive performance, and these associations were partially independent of chronological age. DiscussionSmall sample size limited estimate precision, however, findings suggest future work on telomere length and cognitive health in underrepresented populations at high risk for dementia is feasible and valuable as a foundation for social and behavioral intervention research.

neuroscience↗

Whole genome methylation sequencing in blood from persons with mild cognitive impairment and dementia due to Alzheimer's disease identifies cognitive status

INTRODUCTIONWhole genome methylation sequencing (WGMS) in blood identifies differential DNA methylation in persons with late-onset dementia due to Alzheimers disease (AD) but has not been tested in persons with mild cognitive impairment (MCI). METHODSWe used WGMS to compare DNA methylation levels at 25,244,219 CpG loci in 382 blood samples from 99 persons with MCI, 109 with AD, and 174 who are cognitively unimpaired (CU). RESULTSWGMS identified 9,756 differentially methylated positions (DMPs) in persons with MCI, including 1,743 differentially methylated genes encoding proteins in biological pathways related to synapse organization, dendrite development, and ion transport. 447 DMPs exhibit progressively increasing or decreasing DNA methylation levels between CU, MCI, and AD that correspond to cognitive status. DISCUSSIONWGMS identifies DMPs in known and newly detected genes in blood from persons with MCI and AD that support blood DNA methylation levels as candidate biomarkers of cognitive status.

genomics↗

Gene by environment interaction mouse model reveals a functional role for 5-hydroxymethylcytosine in neurodevelopmental disorders

Mouse knockouts of Cntnap2 exhibit altered neurodevelopmental behavior and a genome-wide disruption of 5-hydroxymethylcytosine (5hmC). Here we examined whether adult Cntnap2 heterozygous mice (Cntnap2+/-, lacking behavioral or neuropathological abnormalities) subjected to a prenatal stress would have disruptions in brain 5hmC levels and exhibit altered behaviors similar to the knockout mice. Adult prenatally stressed Cntnap2+/- female mice showed repetitive behaviors and altered sociability, similar to the homozygote phenotype. Genomic profiling revealed disruptions in hippocampal and striatal 5hmC levels that were correlated to altered transcript levels of genes linked to these phenotypes (e.g., Reln, Dst, Trio and Epha5). Chromatin-immunoprecipitation coupled with high-throughput sequencing and hippocampal nuclear lysate pull-down data indicated that 5hmC abundance alters the binding of the transcription factor CLOCK near the promoters of differentially expressed genes (e.g., Palld, Gigyf1, and Fry), providing a mechanistic role for 5hmC (disruption of transcription factor binding) in gene regulation of developmentally important genes.

genetics↗

Peripheral blood DNA methylation and autism spectrum disorder

Background\n\nSeveral reports have suggested a role for epigenetic mechanisms in ASD etiology. Epigenome-wide association studies (EWAS) in autism spectrum disorder (ASD) may shed light on particular biological mechanisms. However, studies of ASD cases versus controls have been limited by post-mortem timing and severely small sample sizes. Reports from in-life sampling of blood or saliva have also been very limited in sample size, and/or genomic coverage. We present the largest case-control EWAS for ASD to date, combining data from population-based case-control and case-sibling pair studies.\n\nMethods\n\nDNA from 968 blood samples from children in the Study to Explore Early Development (SEED 1) was used to generate epigenome-wide array DNA methylation (DNAm) data at 485,512 CpG sites for 453 cases and 515 controls, using the Illumina 450K Beadchip. The Simons Simplex Collection (SSC) provided 450K array DNAm data on an additional 343 cases and their unaffected siblings. We performed EWAS meta-analysis across results from the two data sets, with adjustment for sex and surrogate variables that reflect major sources of biological variation and technical confounding such as cell type, batch, and ancestry. We compared top EWAS results to those from a previous brain-based analysis. We also tested for enrichment of ASD EWAS CpGs for being targets of meQTL associations using available SNP genotype data in the SEED sample.\n\nFindings\n\nIn this meta-analysis of blood-based DNA from 796 cases and 858 controls, no single CpG met a Bonferroni discovery threshold of p < 1.12x10-7. Seven CpGs showed differences at p < 1x10-5 and 48 at 1x10-4. Of the top 7, 5 showed brain-based ASD associations as well, often with larger effect sizes, and the top 48 overall showed modest concordance (r = 0.31) in direction of effect with cerebellum samples. Finally, we observed suggestive evidence for enrichment of CpG sites controlled by SNPs (meQTL targets) among the EWAS CpGs hits, which was consistent across EWAS and meQTL discovery p-value thresholds.\n\nConclusions\n\nWe report the largest case-control EWAS study of ASD to date. No single CpG site showed a large enough DNAm difference between cases and controls to achieve epigenome-wide significance in this sample size. However, our results suggest the potential to observe disease associations from blood-based samples. Among the 7 sites achieving suggestive statistical significance, we observed consistent, and stronger, effects at the same sites among brain samples. Discovery-oriented EWAS for ASD using blood samples will likely need even larger samples and unified genetic data to further understand DNAm differences in ASD.

genomics↗