Cdkn2a/p16INK4A Loss affects hippocampal transcription in Young Adult Mice Independently of Alzheimer ’s-Associated Genetic Pathways
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE300348 | GEO | 2026/03/11
REPOSITORIES: GEO
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Project description:Detecting and understanding Alzheimer's disease (AD) in its early stages is essential for uncovering the initial mechanisms behind its neuropathology and devising effective interventions. In this study, we leveraged the humanized AppNL-G-F mouse which exhibits early-onset amyloid pathology along a predictable timeline, to investigate molecular changes in the hippocampus and blood before the onset of severe neuropathology and independent of aging. Employing a multi-omics approach, we identified alterations in chromatin accessibility, gene expression, and DNA methylation associated with early amyloidosis. Chromatin accessibility changes were prominent in excitatory neurons during early pathology, with a later shift to inhibitory neurons, potentially reflecting compensatory mechanisms to mitigate excitatory neuron dysregulation. Despite broadly comparable hippocampal cell composition, transcriptomic comparisons between wild-type and AppNL-G-F mice revealed major gene expression differences, particularly in pathways related to mitochondrial function and protein biosynthesis, preceding severe amyloid plaque deposition. In later stages, upregulation of immune and neuroinflammatory pathways was observed, aligning with established neuroinflammatory processes in AD. Additionally, we identified extensive DNA methylation differences in both the blood and hippocampus of AppNL-G-F mice during early and late stages of pathology. Many differentially methylated regions in the blood, even at early pathology stages, were associated with cis-regulatory elements in the brain and were located near differentially expressed genes in the hippocampus. These regions were enriched in pathways related to brain function, such as neuron development and synaptic processes, indicating a link between blood methylation patterns and brain function. This suggests the potential utility of blood methylation as a biomarker for early amyloidosis detection. Notably, we identified five candidate biomarker genes, including Rbfox1 and Camta1, with epigenetic dysregulation detectable in both the brain and blood prior to severe amyloid accumulation. Our study, leveraging a unique AD mouse model and a multi-omics approach, highlights epigenetic signatures of AD before the onset of clinical symptoms, providing a foundation for future research into early diagnosis and therapeutic strategies, as well as potential biomarkers.
2025-11-20 | GSE290305 | GEO
Project description:Detecting and understanding Alzheimer's disease (AD) in its early stages is essential for uncovering the initial mechanisms behind its neuropathology and devising effective interventions. In this study, we leveraged the humanized AppNL-G-F mouse which exhibits early-onset amyloid pathology along a predictable timeline, to investigate molecular changes in the hippocampus and blood before the onset of severe neuropathology and independent of aging. Employing a multi-omics approach, we identified alterations in chromatin accessibility, gene expression, and DNA methylation associated with early amyloidosis. Chromatin accessibility changes were prominent in excitatory neurons during early pathology, with a later shift to inhibitory neurons, potentially reflecting compensatory mechanisms to mitigate excitatory neuron dysregulation. Despite broadly comparable hippocampal cell composition, transcriptomic comparisons between wild-type and AppNL-G-F mice revealed major gene expression differences, particularly in pathways related to mitochondrial function and protein biosynthesis, preceding severe amyloid plaque deposition. In later stages, upregulation of immune and neuroinflammatory pathways was observed, aligning with established neuroinflammatory processes in AD. Additionally, we identified extensive DNA methylation differences in both the blood and hippocampus of AppNL-G-F mice during early and late stages of pathology. Many differentially methylated regions in the blood, even at early pathology stages, were associated with cis-regulatory elements in the brain and were located near differentially expressed genes in the hippocampus. These regions were enriched in pathways related to brain function, such as neuron development and synaptic processes, indicating a link between blood methylation patterns and brain function. This suggests the potential utility of blood methylation as a biomarker for early amyloidosis detection. Notably, we identified five candidate biomarker genes, including Rbfox1 and Camta1, with epigenetic dysregulation detectable in both the brain and blood prior to severe amyloid accumulation. Our study, leveraging a unique AD mouse model and a multi-omics approach, highlights epigenetic signatures of AD before the onset of clinical symptoms, providing a foundation for future research into early diagnosis and therapeutic strategies, as well as potential biomarkers.
2025-11-20 | GSE290154 | GEO
Project description:Detecting and understanding Alzheimer's disease (AD) in its early stages is essential for uncovering the initial mechanisms behind its neuropathology and devising effective interventions. In this study, we leveraged the humanized AppNL-G-F mouse which exhibits early-onset amyloid pathology along a predictable timeline, to investigate molecular changes in the hippocampus and blood before the onset of severe neuropathology and independent of aging. Employing a multi-omics approach, we identified alterations in chromatin accessibility, gene expression, and DNA methylation associated with early amyloidosis. Chromatin accessibility changes were prominent in excitatory neurons during early pathology, with a later shift to inhibitory neurons, potentially reflecting compensatory mechanisms to mitigate excitatory neuron dysregulation. Despite broadly comparable hippocampal cell composition, transcriptomic comparisons between wild-type and AppNL-G-F mice revealed major gene expression differences, particularly in pathways related to mitochondrial function and protein biosynthesis, preceding severe amyloid plaque deposition. In later stages, upregulation of immune and neuroinflammatory pathways was observed, aligning with established neuroinflammatory processes in AD. Additionally, we identified extensive DNA methylation differences in both the blood and hippocampus of AppNL-G-F mice during early and late stages of pathology. Many differentially methylated regions in the blood, even at early pathology stages, were associated with cis-regulatory elements in the brain and were located near differentially expressed genes in the hippocampus. These regions were enriched in pathways related to brain function, such as neuron development and synaptic processes, indicating a link between blood methylation patterns and brain function. This suggests the potential utility of blood methylation as a biomarker for early amyloidosis detection. Notably, we identified five candidate biomarker genes, including Rbfox1 and Camta1, with epigenetic dysregulation detectable in both the brain and blood prior to severe amyloid accumulation. Our study, leveraging a unique AD mouse model and a multi-omics approach, highlights epigenetic signatures of AD before the onset of clinical symptoms, providing a foundation for future research into early diagnosis and therapeutic strategies, as well as potential biomarkers.
2025-11-20 | GSE290397 | GEO
Project description:In Alzheimer’s disease (AD), pathophysiological changes in the hippocampus cause deficits in episodic memory formation, leading to cognitive impairment. Hippocampal hyperactivity and decreased sleep quality are associated with early AD, but their basis is poorly understood. We find that homeostatic mechanisms transiently counteract increased excitatory drive of hippocampal CA1 neurons in AppNL-G-F mice, but fail to stabilize it at control levels. Spatial transcriptomics (ST) analysis identifies the Pmch gene encoding Melanin-Concentrating Hormone (MCH) as part of the adaptive response in AppNL-G-F mice. Hypothalamic MCH peptide is produced in sleep-active lateral hypothalamic neurons that project to CA1 and modulate memory. We show that MCH downregulates synaptic transmission and modulates firing rate homeostasis in hippocampal neurons. Moreover, MCH reverses the increased excitatory drive of CA1 neurons in AppNL-G-F mice. Consistent with our finding that a reduced fraction of MCH-neurons is active in AppNL-G-F mice, these animals spend less time in rapid eye movement (REM) sleep. In addition, MCH-axons projecting to CA1 become progressively impaired in both AppNL-G-F mice and AD patients. Our findings identify the MCH-system as vulnerable in early AD and suggest that impaired MCH-system function contributes to aberrant excitatory drive and sleep defects, which can compromise hippocampal-dependent functions.
2023-09-07 | GSE225181 | GEO
Project description:Background Alzheimer's disease (AD) is intricately linked with neuroinflammation, with the complement system, particularly C3, emerging as a critical player. However, research has been hampered by the reliance on classical germline C3 knockout and APP overexpressing mouse models, which do not allow to study temporal and cell-specific C3 effects, and do not accurately reflect the complexity of AD pathology. Methods In this study, we investigated the impact of conditional C3 deficiency on neuroinflammation and AD pathology, by generating microglia-specific (C3mKO), astrocyte-specific (C3aKO), and inducible full-body (C3iKO) C3 knockout mice. To assess the role of C3 in both acute and chronic neuroinflammation, we employed an intracerebroventricular (ICV) LPS injection model in these mice alongside studies in the AppNL-G-F knock-in mouse model of AD upon aging and mild peripheral inflammation. Results Our results show that complement genes, including C3, are upregulated in microglia and astrocytes from 40 weeks old AppNL-G-F mice compared to their wildtype counterparts. Both microglia and astrocytes were shown to be significant sources of C3, as conditional C3 deficiency in either cell type led to decreased C3 expression and a dampened neuroinflammatory transcriptional response following ICV LPS injection. However, microglial- and astrocytic-specific C3 deficiency in AppNL-G-F mice did not affect total hippocampal C3 protein levels and amyloid plaque burden upon both 40 weeks of aging and in mild peripheral inflammation conditions. Also full-body C3 knockout, induced at the age of 8 weeks, did not alter Aβ pathology and glial activation, despite the complete removal of C3. Conclusions Our findings show that while C3 contributes to neuroinflammatory responses, its role in chronic AD-associated pathology is more complex than previously thought. Our study using novel cell-specific and inducible C3 knockout mice combined with the knock-in AppNL-G-F model provides new insights into the cell-specific roles of complement in AD, and highlights the need for further investigation into the complement system's involvement in neurodegenerative diseases.
2026-06-03 | GSE291239 | GEO
Project description:Alzheimer's disease (AD) is the most common neurodegenerative disorder affecting memory and cognition. The disease is accompanied by an abnormal deposition of ß-amyloid plaques in the brain that contributes to neurodegeneration and is known to induce glial inflammation. Studies in the APP/PS1 mouse model of ß-amyloid-induced neuropathology have suggested a role for inflammasome activation in ß-amyloid-induced neuroinflammation and neuropathology. Here, we evaluated the in vivo role of microglia-selective and full body inflammasome signalling in several mouse models of ß-amyloid-induced AD neuropathology. Unexpectedly, microglia-specific deletion of the inflammasome regulator A20 and inflammasome effector protease caspase-1 in the AppNL-G-F and APP/PS1 models failed to identify a prominent role for microglial inflammasome signalling in ß-amyloid-induced neuropathology. Moreover, global inflammasome inactivation through respectively full body deletion of caspases 1 and 11 in AppNL-G-F mice and Nlrp3 deletion in APP/PS1 mice, also failed to modulate amyloid pathology and disease progression. In agreement, single-cell RNA sequencing did not reveal an important role for Nlrp3 signalling in driving microglial activation and the transition into disease-associated states, both during homeostasis and upon amyloid pathology. Collectively, these results question a generalizable role for inflammasome activation in pre-clinical amyloid-only models of neuroinflammation.
2024-01-17 | GSE249611 | GEO
Project description:Alzheimer’s disease (AD), the leading cause of dementia, is characterized by early synaptic dysfunction that precedes overt cognitive decline. While amyloid-β and Tau remain central to AD pathogenesis, molecular triggers of synapse weakening remain unclear. Here, we investigated AETA, a novel brain-secreted peptide derived from amyloid precursor protein (APP), as a potential mediator of synapse dysfunction in AD. We previously identified AETA as a unique modulator of NMDA receptor activity in the healthy brain; however, its role in AD etiology was yet to be explored. Post-mortem analyses of human hippocampal and prefrontal cortex tissues revealed significantly elevated AETA levels in AD patients, particularly in females. To further explore the contribution of AETA to AD synaptic pathology, we analyzed a new mouse model, the AETA-m mouse, exhibiting chronically increased brain AETA expression. Hippocampi of female AETA-m mice display an increase in the number of astrocyte and microglia, but no overt neuroinflammation. RNA sequencing of female AETA-m hippocampi revealed alterations in synaptic gene expression that closely paralleled those observed in vulnerable human AD brain regions, most notably in the hippocampus. These two phenotypes were absent in males. Functionally, hippocampal neurons from AETA-m mice displayed impaired NMDA receptor signaling, dendritic spine loss, and memory deficits especially in females, mirroring early AD-associated synaptic dysfunction. Together, these findings identify AETA as a novel key contributor of synaptic vulnerability in AD and associated memory processing, especially in females. Targeting AETA signaling may, therefore, offer new therapeutic avenues for preventing or mitigating synaptic and cognitive decline in AD.
2026-06-10 | GSE333329 | GEO
Project description:Elucidating the intricate molecular mechanisms of Alzheimer's disease (AD) requires a multidimensional analysis incorporating various omics data. In this study, we employed transcriptome and proteome profiling of AppNL-G-F, a human APP knock-in model of amyloidosis, at the early and mid-stages of amyloid-beta (Aβ) pathology, to delineate the impacts of Aβ deposition on brain cells. By contrasting AppNL-G-F mice with TREM2 (Triggering receptor expressed on myeloid cells 2) knockout models, our study further investigates the role of TREM2, a well-known AD risk gene, in influencing microglial responses to Aβ pathology. Our results highlight microglial activation as a central feature of Aβ pathology, characterized by the significant upregulation of microglia-specific genes related to immune responses such as complement system and antigen presentation, and catabolic pathways such as phagosome formation and lysosome biogenesis. The absence of TREM2 markedly diminishes the induction of these genes, impairs Aβ clearance, and exacerbates dystrophic neurite formation. Importantly, TREM2 is required for the microglial engagement with Aβ plaques and the formation of compact Aβ plaque cores. Furthermore, this study reveals substantial disruptions in energy metabolism and protein synthesis, signaling a shift from anabolism to catabolism in response to Aβ deposition. This metabolic alteration, coupled with a decrease in synaptic protein abundance, occurs independently of TREM2, suggesting the direct effects of Aβ deposition on synaptic integrity and plasticity. In summary, our findings demonstrate significant microglial activation and metabolic disruption following Aβ deposition, offering mechanistic insights into Aβ pathology and highlighting the potential of targeting these pathways in AD therapy.
2024-10-14 | GSE279164 | GEO
Project description:We had previously performed comparative gene expression profiling of human postmortem Alzheimer’s disease (AD) brains donated for the Hisayama study. The hippocampi from AD brains showed the most significant alteration in gene expression profile [PMID: 23595620]. In the present study, in order to identify molecular pathological alterations in AD hippocampus, we applied human transcriptome array and RNA-sequencing to the same samples and reanalyzed the gene array data, and performed integrative analysis of all 3 methods. We also applied gene array to hippocampus of 6-month-old AppNL-G-F/NL-G-F knock-in AD model mice as a preclinical AD stage model, and at last we performed the interspecies comparison. Functional annotation clustering with the results of all 3 or at least 2 methods in human, showed synapse, cell junction, calmodulin binding, ion transport and glycoproteins as the top affected terms. In hippocampi of AppNL-G-F/NL-G-F mice which exhibit significant amyloidosis but not neuronal degeneration, we found that expression of genes categorized in signaling specially signaling peptides with disulfide bond or glycoproteins, together with the innate immune response and lysosome of cells are upregulated. Comparing the extended human data with mouse data, we found and confirmed by qRT-PCR, 2 common up-regulated genes, Clec7a and C4b, which induce innate immune response and synapse elimination. We also found and confirmed by qRT-PCR, 2 common down-regulated genes, one is Slc17a6, which can affect synaptic transmission of glutamate, and second one is Rxfp1, which is involved in gene transcription. Amyloid-beta accumulation is the major hallmark of AD at 6 month-old AppNL-G-F/NL-G-F mice, therefore our data suggests that amyloid-beta accumulation induces innate immune response, synapse elimination, besides it can decreases glutamate transmission, and affect gene transcription in early stage of hippocampal AD brain, prior to neuronal degeneration.
2024-12-31 | GSE173954 | GEO
Project description:We had previously performed comparative gene expression profiling of human postmortem Alzheimer’s disease (AD) brains donated for the Hisayama study. The hippocampi from AD brains showed the most significant alteration in gene expression profile [PMID: 23595620]. In the present study, in order to identify molecular pathological alterations in AD hippocampus, we applied human transcriptome array and RNA-sequencing to the same samples and reanalyzed the gene array data, and performed integrative analysis of all 3 methods. We also applied gene array to hippocampus of 6-month-old AppNL-G-F/NL-G-F knock-in AD model mice as a preclinical AD stage model, and at last we performed the interspecies comparison. Functional annotation clustering with the results of all 3 or at least 2 methods in human, showed synapse, cell junction, calmodulin binding, ion transport and glycoproteins as the top affected terms. In hippocampi of AppNL-G-F/NL-G-F mice which exhibit significant amyloidosis but not neuronal degeneration, we found that expression of genes categorized in signaling specially signaling peptides with disulfide bond or glycoproteins, together with the innate immune response and lysosome of cells are upregulated. Comparing the extended human data with mouse data, we found and confirmed by qRT-PCR, 2 common up-regulated genes, Clec7a and C4b, which induce innate immune response and synapse elimination. We also found and confirmed by qRT-PCR, 2 common down-regulated genes, one is Slc17a6, which can affect synaptic transmission of glutamate, and second one is Rxfp1, which is involved in gene transcription. Amyloid- accumulation is the major hallmark of AD at 6 month-old AppNL-G-F/NL-G-F mice, therefore our data suggests that amyloid- accumulation induces innate immune response, synapse elimination, besides it can decreases glutamate transmission, and affect gene transcription in early stage of hippocampal AD brain, prior to neuronal degeneration.
2021-12-23 | GSE173955 | GEO