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Abstract Proteomic profiling of brain cell types using isolation-based strategies pose limitations in resolving cellular phenotypes representative of their native state. We describe a mouse line for cell type-specific expression of biotin ligase TurboID, for in vivo biotinylation of proteins. Using adenoviral and transgenic approaches to label neurons, we show robust protein biotinylation in neuronal soma and axons throughout the brain, allowing quantitation of over 2000 neuron-derived proteins spanning synaptic proteins, transporters, ion channels and disease-relevant druggable targets. Next, we contrast Camk2a-neuron and Aldh1l1-astrocyte proteomes and identify brain region-specific proteomic differences within both cell types, some of which might potentially underlie the selective vulnerability to neurological diseases. Leveraging the cellular specificity of proteomic labeling, we apply an antibody-based approach to uncover differences in neuron and astrocyte-derived signaling phospho-proteins and cytokines. This approach will facilitate the characterization of cell-type specific proteomes in a diverse number of tissues under both physiological and pathological states.
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Native-state proteomics of Parvalbumin interneurons identifies unique molecular signatures and vulnerabilities to early Alzheimer’s pathology
Abstract Dysfunction in fast-spiking parvalbumin interneurons (PV-INs) may represent an early pathophysiological perturbation in Alzheimer’s Disease (AD). Defining early proteomic alterations in PV-INs can provide key biological and translationally-relevant insights. We used cell-type-specific in-vivo biotinylation of proteins (CIBOP) coupled with mass spectrometry to obtain native-state PV-IN proteomes. PV-IN proteomic signatures include high metabolic and translational activity, with over-representation of AD-risk and cognitive resilience-related proteins. In bulk proteomes, PV-IN proteins were associated with cognitive decline in humans, and with progressive neuropathology in humans and the 5xFAD mouse model of Aβ pathology. PV-IN CIBOP in early stages of Aβ pathology revealed signatures of increased mitochondria and metabolism, synaptic and cytoskeletal disruption and decreased mTOR signaling, not apparent in whole-brain proteomes. Furthermore, we demonstrated pre-synaptic defects in PV-to-excitatory neurotransmission, validating our proteomic findings. Overall, in this study we present native-state proteomes of PV-INs, revealing molecular insights into their unique roles in cognitive resiliency and AD pathogenesis.
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- Award ID(s):
- 1944053
- PAR ID:
- 10525489
- Publisher / Repository:
- Nature Communications/NCBI
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2041-1723
- Subject(s) / Keyword(s):
- Alzheimer's disease, proteomics
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract While the link between amyloid β (Aβ) accumulation and synaptic degradation in Alzheimer’s disease (AD) is known, the consequences of this pathology on population coding remain unknown. We found that the entropy, a measure of the diversity of network firing patterns, was lower in the dorsal CA1 region in the APP/PS1 mouse model of Aβ pathology, relative to controls, thereby reducing the population’s coding capacity. Our results reveal a network level signature of the deficits Aβ accumulation causes to the computations performed by neural circuits.more » « less
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Abstract BACKGROUNDLimited research has explored the effect of cardiovascular risk and amyloid interplay on cognitive decline in East Asians. METHODSVascular burden was quantified using Framingham's General Cardiovascular Risk Score (FRS) in 526 Korean Brain Aging Study (KBASE) participants. Cognitive differences in groups stratified by FRS and amyloid positivity were assessed at baseline and longitudinally. RESULTSBaseline analyses revealed that amyloid‐negative (Aβ–) cognitively normal (CN) individuals with high FRS had lower cognition compared to Aβ– CN individuals with low FRS (p < 0.0001). Longitudinally, amyloid pathology predominantly drove cognitive decline, while FRS alone had negligible effects on cognition in CN and mild cognitive impairment (MCI) groups. CONCLUSIONOur findings indicate that managing vascular risk may be crucial in preserving cognition in Aβ– individuals early on and before the clinical manifestation of dementia. Within the CN and MCI groups, irrespective of FRS status, amyloid‐positive individuals had worse cognitive performance than Aβ– individuals. HighlightsVascular risk significantly affects cognition in amyloid‐negative older Koreans.Amyloid‐negative CN older adults with high vascular risk had lower baseline cognition.Amyloid pathology drives cognitive decline in CN and MCI, regardless of vascular risk.The study underscores the impact of vascular health on the AD disease spectrum.more » « less
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null (Ed.)Tau pathology in Alzheimer's disease (AD) preferentially afflicts the limbic and recently enlarged association cortices, causing a progression of mnemonic and cognitive deficits. Although genetic mouse models have helped reveal mechanisms underlying the rare, autosomal-dominant forms of AD, the etiology of the more common, sporadic form of AD remains unknown, and is challenging to study in mice due to their limited association cortex and lifespan. It is also difficult to study in human brains, as early-stage tau phosphorylation can degrade postmortem. In contrast, rhesus monkeys have extensive association cortices, are long-lived, and can undergo perfusion fixation to capture early-stage tau phosphorylation in situ. Most importantly, rhesus monkeys naturally develop amyloid plaques, neurofibrillary tangles comprised of hyperphosphorylated tau, synaptic loss, and cognitive deficits with advancing age, and thus can be used to identify the early molecular events that initiate and propel neuropathology in the aging association cortices. Studies to date suggest that the particular molecular signaling events needed for higher cognition—for example, high levels of calcium to maintain persistent neuronal firing- lead to tau phosphorylation and inflammation when dysregulated with advancing age. The expression of NMDAR-NR2B (GluN2B)—the subunit that fluxes high levels of calcium—increases over the cortical hierarchy and with the expansion of association cortex in primate evolution, consistent with patterns of tau pathology. In the rhesus monkey dorsolateral prefrontal cortex, spines contain NMDAR-NR2B and the molecular machinery to magnify internal calcium release near the synapse, as well as phosphodiesterases, mGluR3, and calbindin to regulate calcium signaling. Loss of regulation with inflammation and/or aging appears to be a key factor in initiating tau pathology. The vast expansion in the numbers of these synapses over primate evolution is consistent with the degree of tau pathology seen across species: marmoset < rhesus monkey < chimpanzee < human, culminating in the vast neurodegeneration seen in humans with AD.more » « less
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Background: Sex differences impact Alzheimer’s disease (AD) neuropathology, but cell-to-network level dysfunctions in the prodromal phase are unclear. Alterations in hippocampal excitation-inhibition balance (EIB) have recently been linked to early AD pathology. Objective: Examine how AD risk factors (age, APOE ɛ4, amyloid-β) relate to hippocampal EIB in cognitively normal males and females using connectome-level measures. Methods: Individuals from the OASIS-3 cohort (age 42–95) were studied (N = 437), with a subset aged 65+ undergoing neuropsychological testing (N = 231). Results: In absence of AD risk factors (APOE ɛ4/Aβ+), whole-brain EIB decreases with age more significantly in males than females (p = 0.021, β= –0.007). Regression modeling including APOE ɛ4 allele carriers (Aβ–) yielded a significant positive AGE-by-APOE interaction in the right hippocampus for females only (p = 0.013, β= 0.014), persisting with inclusion of Aβ+ individuals (p = 0.012, β= 0.014). Partial correlation analyses of neuropsychological testing showed significant associations with EIB in females: positive correlations between right hippocampal EIB with categorical fluency and whole-brain EIB with the Trail Making Test (p < 0.05). Conclusions: Sex differences in EIB emerge during normal aging and progresses differently with AD risk. Results suggest APOE ɛ4 disrupts hippocampal balance more than amyloid in females. Increased excitation correlates positively with neuropsychological performance in the female group, suggesting a duality in terms of potential beneficial effects prior to cognitive impairment. This underscores the translational relevance of APOE ɛ4 related hyperexcitation in females, potentially informing therapeutic targets or early interventions to mitigate AD progression in this vulnerable population.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41467-024-47028-7
