Moxibustion Improves Hypothalamus Aqp4 Polarization in APP/PS1 Mice: Evidence from Spatial Transcriptomics
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ABSTRACT: Aquaporin-4 (AQP4) is highly polarized to perivascular astrocytic endfeet. Loss of AQP4 polarization is associated with many diseases. In Alzheimer's disease (AD), it is found that AQP4 loos its normal location and thus reduce the clearance of amyloid-β plaques and Tau protein. Clinical and experimental studies show that moxibustion can improve the learning and memory abilities of AD. In order to explore whether moxibustion can affect the polarization of AQP4 around blood brain barrier (BBB), we used spatial transcriptomics (ST) to analyze the expression and polarization of Aqp4 in wild type mice, APP/PS1 mice and APP/PS1 mice intervened by moxibustion. The results showed that moxibustion improved the loss of abnormal polarization of AQP4 in APP/PS1 mice, especially in the hypothalamic BBB. Besides, there are other 31 genes with Aqp4 as the core have the similar depolarization in APP/PS1 mice, most of which are also membrane proteins. The majority of them have been reversed by moxibustion. At the same time, we employed the cerebrospinal fluid circulation gene set, which was found being on a higher level in the group of APP/PS1 mice with moxibustion treatment. Finally, in order to further explore its mechanism, we analyzed the mitochondrial respiratory chain complex enzymes closely related to energy metabolism, and found that moxibustion can significantly increase the expression of mitochondrial respiratory chain enzymes such as Cox6a2 in the hypothalamus, which could provide energy for mRNA transport. Our research shows that increasing the polarization of hypothalamic Aqp4 through mitochondrial energy supply may be an important target for moxibustion to improve APP/PS1 mice’s cognitive impairment.
Project description:Blood-brain barrier (BBB) dysfunction is emerging as a key pathogenic factor in the progression of Alzheimer’s disease (AD), where increased microvascular endothelial permeability has been proposed to play an important role. However, the molecular mechanisms leading to increased brain microvascular permeability in AD are not fully understood. We observed that brain endothelial permeability in the APPswe/PS1DE9 (APP/PS1) transgenic mouse model of amyloid-beta (Ab) amyloidosis increases with aging in the areas with the greatest amyloid plaque deposition. We performed an unbiased bulk RNA-sequencing analysis of brain endothelial cells (BECs) in APP/PS1 transgenic mice. We observed that upregulation of interferon signaling gene expression pathways in BECs were among the most prominent transcriptomic signatures in the brain endothelium of APP/PS1 mice. Immunofluorescence analysis of isolated BECs from APP/PS1 mice demonstrated higher levels of the Type I interferon-stimulated gene IFIT2. Immunoblotting of APP/PS1 BECs showed downregulation of the adherens junction protein VE-cadherin. Stimulation of human brain endothelial cells with interferon-β decreased the levels of the adherens junction protein VE-cadherin as well as tight junction proteins Occludin and Claudin-5 and increased barrier leakiness. Depletion of the Type I interferon receptor in human brain endothelial cells prevented interferon-β-induced VE- cadherin downregulation and restored endothelial barrier integrity. Our study suggests that Type I interferon signaling contributes to brain endothelial dysfunction in AD.
Project description:Alzheimer’s disease (AD) is an age-related disease, with loss of integrity of the blood-brain barrier (BBB) being an early feature. Cellular senescence is one of the reported nine hallmarks of aging. Here we show for the first time the presence of senescent cells in the vasculature in AD patients and mouse models of AD. Senescent endothelial cells and pericytes are present in APP/PS1 transgenic mice but not in wild-type littermates at the time of amyloid deposition. In vitro, senescent endothelial cells display altered VE-cadherin expression and loss of cell junction formation and increased permeability. Consistent with this, senescent endothelial cells in APP/PS1 mice are present at areas of vascular leak that have decreased claudin-5 and VE-cadherin expression confirming BBB breakdown. Further, single cell sequencing of endothelial cells from APP/PS1 transgenic mice confirms that adhesion molecule pathways are among the most highly altered pathways in these cells. At the pre-plaque stage the vasculature shows significant signs of breakdown, with a general loss of VE-cadherin, leakage within the microcirculation, and obvious pericyte perturbation. Although senescent vascular cells were not directly observed at sites of vascular leak, senescent cells were close to the leak area. Thus, we would suggest in AD there is a progressive induction of senescence in constituents of the neurovascular unit contributing to an increasing loss of vascular integrity. Targeting the vasculature early in AD, either with senolytics or with drugs that improve the integrity of the BBB maybe valid therapeutic strategies.
Project description:The etiology of Alzheimer's disease (AD) has been intensively studied. However, little is known about the molecular alterations in early-stage and late-stage AD. Hence, we performed RNA sequencing and assessed differentially expressed genes (DEGs) in the hippocampus of 18-month and 7-month-old APP/PS1 mice. Moreover, the DEGs induced by treatment with nicotine, the nicotinic acetylcholine receptor agonist that is known to improve cognition in AD, were also analyzed in old and young APP/PS1 mice. When comparing old APP/PS1 mice with their younger littermates, we found an upregulation in genes associated with calcium overload, immune response, cancer, and synaptic function; the transcripts of 14 calcium ion channel subtypes were significantly increased in aged mice. In contrast, the downregulated genes in aged mice were associated with ribosomal components, mitochondrial respiratory chain complex, and metabolism. Through comparison with DEGs in normal aging from previous reports, we found that changes in calcium channel genes remained one of the prominent features in aged APP/PS1 mice. Nicotine treatment also induced changes in gene expression. Indeed, nicotine augmented glycerolipid metabolism, but inhibited PI3K and MAPK signaling in young mice. In contrast, nicotine affected genes associated with cell senescence and death in old mice. Our study suggests a potential network connection between calcium overload and cellular signaling, in which additional nicotinic activation might not be beneficial in late-stage AD
Project description:The assay for transposase-accessible chromatin by sequencing (ATAC-seq) was used to investigate the AD-associated chromatin reshaping in the APPswe/PS1dE9 (APP/PS1) mouse model. ATAC-seq data in the hippocampus of 8-month-old APP/PS1 mice were generated, and the relationship between chromatin accessibility and gene expression was analyzed in combination with RNA-sequencing.We identified 1690 increased AD-associated chromatin accessible regions in the hippocampal tissues of APP/PS1 mice and 1003 decreased chromatin accessible regions were considered to be related with declined AD-associated biological processes.In the APP/PS1 hippocampus, 1090 genes were found to be up-regulated and 1081 down-regulated. Interestingly, enhanced ATAC-seq signal was found in approximately 740 genes, with 43 exhibiting up-regulated mRNA levels.Our study reveals that alterations in chromatin accessibility may be an initial mechanism in AD pathogenesis.
Project description:The assay for transposase-accessible chromatin by sequencing (ATAC-seq) was used to investigate the AD-associated chromatin reshaping in the APPswe/PS1dE9 (APP/PS1) mouse model. ATAC-seq data in the hippocampus of 8-month-old APP/PS1 mice were generated, and the relationship between chromatin accessibility and gene expression was analyzed in combination with RNA-sequencing.We identified 1690 increased AD-associated chromatin accessible regions in the hippocampal tissues of APP/PS1 mice and 1003 decreased chromatin accessible regions were considered to be related with declined AD-associated biological processes.In the APP/PS1 hippocampus, 1090 genes were found to be up-regulated and 1081 down-regulated. Interestingly, enhanced ATAC-seq signal was found in approximately 740 genes, with 43 exhibiting up-regulated mRNA levels.Our study reveals that alterations in chromatin accessibility may be an initial mechanism in AD pathogenesis.
Project description:Glucose hypometabolism is one of the major characteristics of Alzheimer's disease (AD). The energy deficiency in AD brain has been at least partially attributed to accelerated mitochondrial dysfunction than normal aging. In earlier publications, we have shown that small molecule mitochondrial complex I inhibitor CP2 facilitated mitochondrial regeneration and rescued mitochondrial deficiency in familial AD mice model APP-PS1. Here in this study, we investigated whether a typical mitochondrial deficiency mouse model could recapitulate molecular expression signatures of AD brain and whether CP2 was able to rescue the AD brain phenotype. Ndufs4 is one of the regulatory subunits of mitochondria complex I. Knockout of Ndufs4 resulted in complex I assembly failure and approximately half mitochondrial function loss. Ndufs4-knockout mice are viable but are short in lifespan (up to about 90 days). This model has been previously used to study Leigh syndrome, a heritable mitochondrial deficiency disease. In this dataset, we performed RNAseq on brains of CP2 treated Ndufs4-knockout mice and examined the expression changes upon CP2 treatment.
Project description:Alzheimer’s disease (AD) is an age-related neurodegenerative disorder characterized by accumulation of amyloid β-peptide (Aβ) plaques in the brain and decreased cognitive function leading to dementia. We determined if hydroxyurea (HU), a ribonucleotide reductase inhibitor known to activate adaptive cellular stress responses in fibroblasts, could protect rat hippocampal neurons against oxidative-, excitatory-, mitochondrial-, and Aβ-induced stress and if HU treatment could improve learning and memory in a mouse model of AD (APP/PS1 double mutant transgenic mice). HU treatment attenuated the loss of cell viability induced by treatment of hippocampal neurons with hydrogen peroxide, glutamate, rotenone, and Aβ1-42. HU treatment also attenuated reductions of mitochondrial reserve capacity, maximal respiration, and cellular ATP content induced by hydrogen peroxide treatment. In vivo, treatment of APP/PS1 AD mice with HU (45 mg/kg/day) improved spatial memory performance in the hippocampus-dependent Morris water maze task. In summary, HU provides neuroprotection against toxic insults, improves mitochondrial bioenergetics, and improves spatial memory in a mouse model of AD. HU may offer a new therapeutic approach to delay cognitive decline in AD.
Project description:Alzheimer’s disease (AD) is an age-related neurodegenerative disorder characterized by accumulation of amyloid β-peptide (Aβ) plaques in the brain and decreased cognitive function leading to dementia. We determined if hydroxyurea (HU), a ribonucleotide reductase inhibitor known to activate adaptive cellular stress responses in fibroblasts, could protect rat hippocampal neurons against oxidative-, excitatory-, mitochondrial-, and Aβ-induced stress and if HU treatment could improve learning and memory in a mouse model of AD (APP/PS1 double mutant transgenic mice). HU treatment attenuated the loss of cell viability induced by treatment of hippocampal neurons with hydrogen peroxide, glutamate, rotenone, and Aβ1-42. HU treatment also attenuated reductions of mitochondrial reserve capacity, maximal respiration, and cellular ATP content induced by hydrogen peroxide treatment. In vivo, treatment of APP/PS1 AD mice with HU (45 mg/kg/day) improved spatial memory performance in the hippocampus-dependent Morris water maze task. In summary, HU provides neuroprotection against toxic insults, improves mitochondrial bioenergetics, and improves spatial memory in a mouse model of AD. HU may offer a new therapeutic approach to delay cognitive decline in AD.
Project description:Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. So far, there is no effective treatment for this condition. Tetramethylpyrazine (TMP) is an alkaloid extracted from traditional Chinese medicine chuanxiong, which is mainly used in the treatment of ischemic stroke some related diseases. In this study, we studied the potential effects of TMP on AD progression by using two AD mouse models. 8-month-old 3xTg-AD mice received TMP treatment (10mg/kg/d) for 1 month, and 4-month-old APP/PS1-AD mice received TMP treatment (10mg/kg/d) for 2 months. The behavioral tests by step-down passive avoidance test (SDA), new object recognition (NOR) and Morris water maze (MWM) showed that TMP significantly improved the learning and memory impairment of two AD transgenic mice. In addition, TMP reduced Aß levels and tau phosphorylation. Venny analysis showed that 116 differentially expressed proteins were commonly changed in 3xTg mice vs WT mice and TMP treated mice vs untreated mice. The same, 130 differentially expressed proteins were commonly changed in APP/PS1 mice vs WT mice and TMP treated mice vs untreated mice. The functions of the common proteins modified by TMP in the two models were mainly related to mitochondrial function, synaptic function, cytoskeleton, GTP binding, ATP binding. Mitochondrial omics analysis revealed 21 and 20 differentially expressed mitochondrial proteins modified by TMP in 3xTg-AD mice and APP/PS1 mice, respectively. These differential proteins were located in mitochondrial inner membrane, mitochondrial outer membrane, mitochondrial gap and mitochondrial matrix, and the function of some proteins is closely related to oxidative phosphorylation of (OXPHOS). Western-blot further validated that TMP changed the expression of OXPHOS complex proteins (sdhb, ndufa10, uqcrfs1, cox5b, atp5a) in the hippocampus of the two AD mice. Taken together, our study demonstrated that TMP improved the cognitive impairment and AD-like pathology, and modified hippocampal proteome in the two AD mice models. The improvement of the behavioral and pathology might be associated with modification of mitochondrial protein profile by TMP. Our study suggested that TMP had the potential for the treatment of AD.