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Maternal choline supplementation protects against age-associated cholinergic and GABAergic basal forebrain neuron degeneration in the Ts65Dn mouse model of Down syndrome and Alzheimer's disease

Gautier, Megan K; Kelley, Christy M; Lee, Sang Han; Alldred, Melissa J; McDaid, John; Mufson, Elliott J; Stutzmann, Grace E; Ginsberg, Stephen D
Down syndrome (DS) is a genetic disorder caused by triplication of human chromosome 21. In addition to intellectual disability, DS is defined by a premature aging phenotype and Alzheimer's disease (AD) neuropathology, including septohippocampal circuit vulnerability and degeneration of basal forebrain cholinergic neurons (BFCNs). The Ts65Dn mouse model recapitulates key aspects of DS/AD pathology, namely age-associated atrophy of BFCNs and cognitive decline in septohippocampal-dependent behavioral tasks. We investigated whether maternal choline supplementation (MCS), a well-tolerated treatment modality, protects vulnerable BFCNs from age- and genotype-associated degeneration in trisomic offspring. We also examined the effect of trisomy, and MCS, on GABAergic basal forebrain parvalbumin neurons (BFPNs), an unexplored neuronal population in this DS model. Unbiased stereological analyses of choline acetyltransferase (ChAT)-immunoreactive BFCNs and parvalbumin-immunoreactive BFPNs were conducted using confocal z-stacks of the medial septal nucleus and the vertical limb of the diagonal band (MSN/VDB) in Ts65Dn mice and disomic (2N) littermates at 3-4 and 10-12 months of age. MCS trisomic offspring displayed significant increases in ChAT-immunoreactive neuron number and density compared to unsupplemented counterparts, as well as increases in the area of the MSN/VDB occupied by ChAT-immunoreactive neuropil. MCS also rescued BFPN number and density in Ts65Dn offspring, a novel rescue of a non-cholinergic cell population. Furthermore, MCS prevented age-associated loss of BFCNs and MSN/VDB regional area in 2N offspring, indicating genotype-independent neuroprotective benefits. These findings demonstrate MCS provides neuroprotection of vulnerable BFCNs and non-cholinergic septohippocampal BFPNs, indicating this modality has translational value as an early life therapy for DS, as well as extending benefits to the aging population at large.
PMID: 37890559
ISSN: 1095-953x
CID: 5608002

Basal forebrain cholinergic neurons are vulnerable in a mouse model of Down syndrome and their molecular fingerprint is rescued by maternal choline supplementation

Alldred, Melissa J; Pidikiti, Harshitha; Heguy, Adriana; Roussos, Panos; Ginsberg, Stephen D
Basal forebrain cholinergic neuron (BFCN) degeneration is a hallmark of Down syndrome (DS) and Alzheimer's disease (AD). Current therapeutics in these disorders have been unsuccessful in slowing disease progression, likely due to poorly understood complex pathological interactions and dysregulated pathways. The Ts65Dn trisomic mouse model recapitulates both cognitive and morphological deficits of DS and AD, including BFCN degeneration and has shown lifelong behavioral changes due to maternal choline supplementation (MCS). To test the impact of MCS on trisomic BFCNs, we performed laser capture microdissection to individually isolate choline acetyltransferase-immunopositive neurons in Ts65Dn and disomic littermates, in conjunction with MCS at the onset of BFCN degeneration. We utilized single population RNA sequencing (RNA-seq) to interrogate transcriptomic changes within medial septal nucleus (MSN) BFCNs. Leveraging multiple bioinformatic analysis programs on differentially expressed genes (DEGs) by genotype and diet, we identified key canonical pathways and altered physiological functions within Ts65Dn MSN BFCNs, which were attenuated by MCS in trisomic offspring, including the cholinergic, glutamatergic and GABAergic pathways. We linked differential gene expression bioinformatically to multiple neurological functions, including motor dysfunction/movement disorder, early onset neurological disease, ataxia and cognitive impairment via Ingenuity Pathway Analysis. DEGs within these identified pathways may underlie aberrant behavior in the DS mice, with MCS attenuating the underlying gene expression changes. We propose MCS ameliorates aberrant BFCN gene expression within the septohippocampal circuit of trisomic mice through normalization of principally the cholinergic, glutamatergic, and GABAergic signaling pathways, resulting in attenuation of underlying neurological disease functions.
PMID: 37191946
ISSN: 1530-6860
CID: 5503542

Microisolation of Spatially Characterized Single Populations of Neurons for RNA Sequencing from Mouse and Postmortem Human Brain Tissues

Alldred, Melissa J; Ginsberg, Stephen D
Single-cell and single-population RNA sequencing (RNA-seq) is a rapidly evolving new field of intense investigation. Recent studies indicate unique transcriptomic profiles are derived based on the spatial localization of neurons within circuits and regions. Individual neuronal subtypes can have vastly different transcriptomic fingerprints, well beyond the basic excitatory neuron and inhibitory neuron designations. To study single-population gene expression profiles of spatially characterized neurons, we have developed a methodology combining laser capture microdissection (LCM), RNA purification of single populations of neurons, and subsequent library preparation for downstream applications, including RNA-seq. LCM provides the benefit of isolating single neurons characterized by morphology or via transmitter-identified and/or receptor immunoreactivity and enables spatial localization within the sample. We utilize unfixed human postmortem and mouse brain tissue that is frozen to preserve RNA quality in order to isolate the desired neurons of interest. Microisolated neurons are then pooled for RNA purification utilizing as few as 250 individual neurons from a tissue section, precluding extraneous nonspecific tissue contaminants. Library preparation is performed from picogram RNA quantities extracted from LCM-captured neurons. Single-population RNA-seq analysis demonstrates that microisolated neurons from both postmortem human and mouse brain tissues are viable for transcriptomic profiling, including differential gene expression assessment and bioinformatic pathway inquiry.
PMCID:10179294
PMID: 37176744
ISSN: 2077-0383
CID: 5544672

Application of robust regression in translational neuroscience studies with non-Gaussian outcome data

Malek-Ahmadi, Michael; Ginsberg, Stephen D; Alldred, Melissa J; Counts, Scott E; Ikonomovic, Milos D; Abrahamson, Eric E; Perez, Sylvia E; Mufson, Elliott J
Linear regression is one of the most used statistical techniques in neuroscience, including the study of the neuropathology of Alzheimer's disease (AD) dementia. However, the practical utility of this approach is often limited because dependent variables are often highly skewed and fail to meet the assumption of normality. Applying linear regression analyses to highly skewed datasets can generate imprecise results, which lead to erroneous estimates derived from statistical models. Furthermore, the presence of outliers can introduce unwanted bias, which affect estimates derived from linear regression models. Although a variety of data transformations can be utilized to mitigate these problems, these approaches are also associated with various caveats. By contrast, a robust regression approach does not impose distributional assumptions on data allowing for results to be interpreted in a similar manner to that derived using a linear regression analysis. Here, we demonstrate the utility of applying robust regression to the analysis of data derived from studies of human brain neurodegeneration where the error distribution of a dependent variable does not meet the assumption of normality. We show that the application of a robust regression approach to two independent published human clinical neuropathologic data sets provides reliable estimates of associations. We also demonstrate that results from a linear regression analysis can be biased if the dependent variable is significantly skewed, further indicating robust regression as a suitable alternate approach.
PMCID:10847267
PMID: 38328735
ISSN: 1663-4365
CID: 5632352

Single-Nucleus Transcriptomic Analysis of the Prefrontal Cortex During Development and Early-Life Stress [Meeting Abstract]

Menezes, E; Abreu, F; Alldred, M; Teixeira, C
Background: The brain contains interconnected circuits which are neither completed at birth or invariant across life. This neuronal plasticity is essential for life-long adaptive features like continuous learning and memory. However, this plasticity, especially when associated with severe adverse factors during early-life, can lead to the derailment of normative brain development and contribute to the etiology of behavioral deficits and psychiatric disorders. One of the most influential environmental factors during early-life is parental/caregiver care. Childhood adversity has been estimated to account for a significant percentage of adult-onset mental health disorders. In extreme cases of childhood adversity, institutional rearing where the infants were deprived of caregiver contact, cognitive deficits and dysregulated prefrontal cortex (PFC) function were found. In this study we hypothesize that earlylife adversity, in the form of maternal separation, leads to longlasting changes in the transcriptome of specific PFC cell populations leading to a dysregulation of PFC function.
Method(s): Here, we use a mouse model of maternal separation. The brains of pups and adults of normal reared or maternal separated (MS) animals were collected. In one set, we performed single-nucleus RNAseq with hashing to contrast the PFC transcriptome of these groups. In a separate cohort, we recorded whole slice voltage dye (VSD) responses to explore how changes in receptors identified by snRNAseq altered PFC responses.
Result(s): Using snRNAseq, as expected, we observed that the changes between ages were much more accentuated than changes between treatments. We also observed that the proportion of oligodendrocytes in adult-MS animals was similar to infant animals. Furthermore, we found that most of the differential gene expression between MS and standard reared animals was in interneurons, affecting pathways related to GABAergic, glutamatergic, and serotonergic functions. Using VSD we observed that adult-MS responses to GABAergic and serotonergic agonists were similar to the responses of more immature normal-reared animals.
Conclusion(s): This study suggests that MS leads to an immature PFC that may be linked to the behavioral deficits observed in animals and humans exposed to poor early-life care
EMBASE:639855716
ISSN: 1740-634x
CID: 5511602

Correction to: Profiling Basal Forebrain Cholinergic Neurons Reveals a Molecular Basis for Vulnerability Within the Ts65Dn Model of Down Syndrome and Alzheimer's Disease

Alldred, Melissa J; Penikalapati, Sai C; Lee, Sang Han; Heguy, Adriana; Roussos, Panos; Ginsberg, Stephen D
PMID: 34837629
ISSN: 1559-1182
CID: 5063972

Expression and proteolytic processing of the amyloid precursor protein is unaffected by the expression of the three human apolipoprotein E alleles in the brains of mice

Novy, Mariah J; Newbury, Samantha F; Liemisa, Braison; Morales-Corraliza, Jose; Alldred, Melissa J; Ginsberg, Stephen D; Mathews, Paul M
The 3 human apolipoprotein E (APOE) gene alleles modify an individual's risk of developing Alzheimer's disease (AD): compared to the risk-neutral APOE ε3 allele, the ε4 allele (APOE4) is strongly associated with increased AD risk while the ε2 allele is protective. Multiple mechanisms have been shown to link APOE4 expression and AD risk, including the possibility that APOE4 increases the expression of the amyloid precursor protein (APP) (Y-W.A. Huang, B. Zhou, A.M. Nabet, M. Wernig, T.C. Südhof, 2019). In this study, we investigated the impact of APOE genotype on the expression, and proteolytic processing of endogenously expressed APP in the brains of mice humanized for the 3 APOE alleles. In contrast to prior studies using neuronal cultures, we found in the brain that both App gene expression, and the levels of APP holoprotein were not affected by APOE genotype. Additionally, our analysis of APP fragments showed that APOE genotype does not impact APP processing in the brain: the levels of both α- and β-cleaved soluble APP fragments (sAPPs) were similar across genotypes, as were the levels of the membrane-associated α- and β-cleaved C-terminal fragments (CTFs) of APP. Lastly, APOE genotype did not impact the level of soluble amyloid beta (Aβ). These findings argue that the APOE-allele-dependent AD risk is independent of the brain expression and processing of APP.
PMID: 34875506
ISSN: 1558-1497
CID: 5099572

Profiling Basal Forebrain Cholinergic Neurons Reveals a Molecular Basis for Vulnerability Within the Ts65Dn Model of Down Syndrome and Alzheimer's Disease

Alldred, Melissa J; Penikalapati, Sai C; Lee, Sang Han; Heguy, Adriana; Roussos, Panos; Ginsberg, Stephen D
Basal forebrain cholinergic neuron (BFCN) degeneration is a hallmark of Down syndrome (DS) and Alzheimer's disease (AD). Current therapeutics have been unsuccessful in slowing disease progression, likely due to complex pathological interactions and dysregulated pathways that are poorly understood. The Ts65Dn trisomic mouse model recapitulates both cognitive and morphological deficits of DS and AD, including BFCN degeneration. We utilized Ts65Dn mice to understand mechanisms underlying BFCN degeneration to identify novel targets for therapeutic intervention. We performed high-throughput, single population RNA sequencing (RNA-seq) to interrogate transcriptomic changes within medial septal nucleus (MSN) BFCNs, using laser capture microdissection to individually isolate ~500 choline acetyltransferase-immunopositive neurons in Ts65Dn and normal disomic (2N) mice at 6 months of age (MO). Ts65Dn mice had unique MSN BFCN transcriptomic profiles at ~6 MO clearly differentiating them from 2N mice. Leveraging Ingenuity Pathway Analysis and KEGG analysis, we linked differentially expressed gene (DEG) changes within MSN BFCNs to several canonical pathways and aberrant physiological functions. The dysregulated transcriptomic profile of trisomic BFCNs provides key information underscoring selective vulnerability within the septohippocampal circuit. We propose both expected and novel therapeutic targets for DS and AD, including specific DEGs within cholinergic, glutamatergic, GABAergic, and neurotrophin pathways, as well as select targets for repairing oxidative phosphorylation status in neurons. We demonstrate and validate this interrogative quantitative bioinformatic analysis of a key dysregulated neuronal population linking single population transcript changes to an established pathological hallmark associated with cognitive decline for therapeutic development in human DS and AD.
PMID: 34263425
ISSN: 1559-1182
CID: 4937542

Adiponectin Modulation by Genotype and Maternal Choline Supplementation in a Mouse Model of Down Syndrome and Alzheimer's Disease

Alldred, Melissa J; Lee, Sang Han; Ginsberg, Stephen D
Down syndrome (DS) is a genetic disorder caused by the triplication of human chromosome 21, which results in neurological and physiological pathologies. These deficits increase during aging and are exacerbated by cognitive decline and increase of Alzheimer's disease (AD) neuropathology. A nontoxic, noninvasive treatment, maternal choline supplementation (MCS) attenuates cognitive decline in mouse models of DS and AD. To evaluate potential underlying mechanisms, laser capture microdissection of individual neuronal populations of MCS offspring was performed, followed by RNA sequencing and bioinformatic inquiry. Results at ~6 months of age (MO) revealed DS mice (the well-established Ts65Dn model) have significant dysregulation of select genes within the Type 2 Diabetes Mellitus (T2DM) signaling pathway relative to normal disomic (2N) littermates. Accordingly, we interrogated key T2DM protein hormones by ELISA assay in addition to gene and encoded protein levels in the brain. We found dysregulation of adiponectin (APN) protein levels in the frontal cortex of ~6 MO trisomic mice, which was attenuated by MCS. APN receptors also displayed expression level changes in response to MCS. APN is a potential biomarker for AD pathology and may be relevant in DS. We posit that changes in APN signaling may be an early marker of cognitive decline and neurodegeneration.
PMCID:8267749
PMID: 34279477
ISSN: 2077-0383
CID: 4947912

Mitovesicles are a novel population of extracellular vesicles of mitochondrial origin altered in Down syndrome

D'Acunzo, Pasquale; Pérez-González, Rocío; Kim, Yohan; Hargash, Tal; Miller, Chelsea; Alldred, Melissa J; Erdjument-Bromage, Hediye; Penikalapati, Sai C; Pawlik, Monika; Saito, Mitsuo; Saito, Mariko; Ginsberg, Stephen D; Neubert, Thomas A; Goulbourne, Chris N; Levy, Efrat
Mitochondrial dysfunction is an established hallmark of aging and neurodegenerative disorders such as Down syndrome (DS) and Alzheimer's disease (AD). Using a high-resolution density gradient separation of extracellular vesicles (EVs) isolated from murine and human DS and diploid control brains, we identify and characterize a previously unknown population of double-membraned EVs containing multiple mitochondrial proteins distinct from previously described EV subtypes, including microvesicles and exosomes. We term these newly identified mitochondria-derived EVs "mitovesicles." We demonstrate that brain-derived mitovesicles contain a specific subset of mitochondrial constituents and that their levels and cargo are altered during pathophysiological processes where mitochondrial dysfunction occurs, including in DS. The development of a method for the selective isolation of mitovesicles paves the way for the characterization in vivo of biological processes connecting EV biology and mitochondria dynamics and for innovative therapeutic and diagnostic strategies.
PMID: 33579698
ISSN: 2375-2548
CID: 4786222