scholarly journals Transcriptional signature in microglia isolated from an Alzheimers disease mouse model treated with scanning ultrasound

2021 ◽  
Author(s):  
Gerhard Leinenga ◽  
Liviu-Gabriel Bodea ◽  
Jan Schroder ◽  
Giuzhi Sun ◽  
Yi Chen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mouse Model ◽  
Microglial Cells ◽  
Wild Type ◽  
Bioinformatics Pipeline ◽  
Transcriptional Signature ◽  
App23 Mouse ◽  
Differential Gene ◽  
Model Versus ◽  
Ad Mouse Model

Rationale: Intracranial scanning ultrasound combined with intravenously injected microbubbles (SUS+MB) transiently opens the blood-brain barrier and reduces amyloid-beta (Abeta) pathology in the APP23 mouse model of Alzheimer disease (AD). This has been accomplished, at least in part, through the activation of microglial cells; however, their response to the SUS treatment is only incompletely understood. Methods: Wild-type (WT) and APP23 mice were subjected to SUS+MB, using non-SUS+MB-treated mice as sham controls. After 48 hours, the APP23 mice were injected with methoxy-XO4 to label Abeta aggregates, followed by microglial isolation into XO4+ and XO4- populations using flow cytometry. Both XO4+ and XO4- cells were subjected to RNA sequencing and their transcriptome was analyzed through a bioinformatics pipeline. Results: The transcriptomic analysis of the microglial cells revealed a clear segregation depending on genotype (AD model versus WT mice), as well as treatment (SUS+MB versus sham) and Abeta internalization (XO4+ versus XO4- microglia). Differential gene expression analysis detected 278 genes that were significantly changed by SUS+MB in the XO4+ cells (248 up/30 down) and 242 in XO- cells (225 up/17 down). Not surprisingly given previous findings of increased phagocytosis of plaques following SUS+MB, the pathway analysis highlighted that the treatment induced an enrichment in genes related to the phagosome pathway in XO4+ microglia; however, when comparing SUS+MB to sham, the analysis revealed an enrichment in genes involved in the cell cycle in both the XO4+ and XO4- microglial population. Conclusion: Our data provide a comprehensive analysis of microglia in an AD mouse model subjected to ultrasound treatment as a function of Abeta internalization, one of the defining hallmarks of AD. Several differentially expressed genes are highlighted, pointing to an ultrasound-induced activation of cell cycle mechanisms in microglial cells isolated from APP23 mice treated with SUS+MB.

BCL-2 Inhibition with ABT-737 Prolongs Survival in an NRAS/BCL2-Mediated MOUSE MODEL of Myelodyspastic Syndrome (MDS) Progressing to ACUTE Myelogenous Leukemia (AML) by Targeting Leukemia Initiating CELLS

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 678-678
Author(s):  
Petra Gorombei ◽  
Beurlet Stephanie ◽  
Nader Omidvar ◽  
Krief Patricia ◽  
Le Pogam Carole ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Bone Marrow ◽  
Stem Cell ◽  
High Risk ◽  
Mouse Model ◽  
Transgenic Mouse Model ◽  
Wild Type ◽  
Double Transgenic Mouse ◽  
Apoptotic Genes

Abstract Abstract 678 Background and aims: BCL-2 activation plays a role in the progression of MDS to AML and BCL 2 inhibition may represent a therapeutic target in such patients. Using our double transgenic mouse model MRP8[NRASD12/BCL2], in which the transgenes induce MDS progressing to AML with dysplasia (Omidvar Cancer Res, 2007), we assessed the effect of ABT-737, a small molecule and mimetic inhibitor binding the BH3 domain of the BCL-2 family of proteins, on survival and leukemia initiating cells (LIC) in this mouse model. Methods: In this MRP8[NRASD12/hBCL2] double transgenic mouse model 2-week old mice have MDS with a mean of 6% bone marrow (BM) blasts (compared with 3% in the normal wild type littermates), while adult mice have AML, with a mean of 60% marrow blasts. In the present study, double transgenic mice were treated just after weaning and genotyping at 3 weeks of age with 75 mg/kg dose of ABT-737 (MDA & Abbott) 3 times weekly for 30 days. A cohort of mice (60 untreated and 35 treated) was followed for survival. Mice were sacrificed and BM harvested after treatment and Giemsa stained for BM analysis by microscopy (n=6 in each group), for LICs characterized as part of the lineage negative (Lin-)/Sca1+/cKit+ (LSK) population by flow cytometry (in 8 treated and 12 untreated mice), and for progenitor assays (n=4 in each group). Hematoxylin and eosin stained liver sections were examined and apoptosis assessed by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) assays of liver sections (n=4 per group). RNA was extracted from Sca+ enriched spleen cells from untreated and treated mice (n=3 from each group) and assayed for gene expression profiling using exon specific arrays (Affymetrix). Results: Survival from birth of 35 treated mice was significantly longer than for 60 untreated mice (p<0.0001) underscoring drug efficacy and tolerance (Fig. 1). This correlated with a reduction of bone marrow blasts (19%±7% in treated versus 60%±6% in untreated mice, p<0.0001). After ABT-737 treatment, the proportion of BM LSK cell population decreased to nearly normal levels (normal wild type littermates mean of 3%, n=4) (12.9±1.4 in untreated versus 6.4±1.1 in treated, p<0.005)) with a complete restoration of colony growth to normal range (40±10 in wild type normal mice, 79.6±7.0 in untreated versus 48.6±13.5 in treated, p<0.01). Decreased invasion of the liver and spleen was observed due to increased apoptosis (3±2 in untreated to 50±12% in treated, p<0.001). Exon specific gene expression arrays with Sca1+ enriched splenocytes showed that 997 genes were differentially expressed between the treated and the untreated mice; 764 and 233 genes were upregulated and downregulated respectively amongst which were upregulated genes important for stem cell development, maintenance and differentiation such as TCF712 (or TCF4), PIWII2, BRMPR1a and Spp1. This may reflect the partial restoration of normal stem cell function, which is consistent with the reduced LSK and progenitor numbers. Downregulation of anti-apoptotic genes such as BCL-2a1b or upregulation of pro-apoptotic genes such as PARP4, CALPAIN2, TNFR, and CARD was observed, consistent with the TUNEL data. Restoration of normal hematopoiesis was confirmed by the upregulation of myeloid differentiation genes (CD14, CSF1, RARalpha) and down regulation of genes implicated in cell cycle (Hsp60, MYC and E2F1). Conclusions: ABT-737 extends lifespan in NRASD12/BCL2 transgenic mice, a preclinical model of high risk MDS/AML. ABT-737 targets the leukemia initiating cell, and regulates, amongst several, cell cycle (proliferation), differentiation and apoptosis pathways. These data suggest that clinical trials in high risk MDS and AML patients are warranted. Disclosures: Grange: Genosplice Technology: Employment.

A Mouse Model of Hematopoietic Stem Cell Failure Associated with p53-Loss and Defective Fbw7-Dependent Cyclin E Regulation.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2297-2297
Author(s):  
Ka Tat Siu ◽  
Yanfei Xu ◽  
Mitra Bhattacharyya ◽  
Alexander C. Minella
Keyword(s):  
Cell Cycle ◽  
Mouse Model ◽  
Conflicts Of Interest ◽  
Cyclin E ◽  
Cell Cycle Control ◽  
Control Mechanisms ◽  
Wild Type ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract Abstract 2297 Recent findings have challenged the notion that increased proliferation of hematopoietic stem cells (HSCs) necessarily restricts their self-renewal capacity. We have studied the physiologic consequences to HSCs of ablating a key cell cycle regulatory mechanism, Fbw7-dependent cyclin E ubiquitination, using germline knock-in of a cyclin ET74A T393A allele. Fbw7 is a tumor suppressor that regulates the abundance of several oncoprotein substrates by ubiquitin-mediated proteolysis, including cyclin E, Notch, and c-Myc. Cyclin E overexpression in vivo is associated with increased proliferation in some cellular contexts as well as a variety of deleterious consequences, including genomic instability, senescence, or apoptosis. In HSCs, Fbw7-loss has been shown to induce self-renewal and multi-lineage reconstitution defects, and the effect of Fbw7-loss in HSCs has been ascribed to dysregulated Myc and Notch expression. Using the cyclin ET74A T393A mouse model, we tested the hypothesis that impaired Fbw7-mediated regulation of cyclin E, specifically, promotes HSC exhaustion due to loss of self-renewal capacity. We first examined bone marrow HSC counts and their cell cycle kinetics in cyclin E knock-in and wild-type control mice at steady state and following hematologic injury induced by 5-fluorouracil treatment. We found that cyclin E dysregulation reduces numbers of quiescent HSCs and increases cells in S/G2/M-phases, while decreasing total numbers of HSCs, phenotypes made more severe after recovery from hematologic stress. Using bromodeoxyuridine labeling studies, we found that excess cyclin E activity causes DNA hyper-replication in cyclin ET74A T393A HSCs in a cell autonomous manner. By enumerating multi-potent progenitors (MPPs), we ruled out increased rate of transit from HSC-to-MPP as a cause of the apparent exhaustion of cyclin E knock-in HSCs. Thus, dysregulated cyclin E in HSCs promotes both increased proliferation and depletion of the HSC pool. Serial transplantation further revealed peripheral blood reconstitution defects associated with cyclin ET74A T393A HSCs. Recently, we have found that p53 is activated by dysregulated cyclin E in hematopoietic cells in vivo, in association with phosphorylation of both p53 and Chk1 proteins, resembling a DNA damage-type response. Interestingly, p53-loss has been found to be associated with a gain of HSC self-renewal activity. We therefore hypothesized that p53-loss would rescue the self-renewal defect of cyclin E knock-in HSCs. Surprisingly, we discovered that cyclin ET74A T393A; p53-null HSCs showed evidence of significantly worse self-renewal and peripheral reconstitution, compared to p53-null HSCs, defects that are more severe than those associated with impaired Fbw7-mediated cyclin E control in the setting of wild-type p53 (Chi-squared test, p<0.0001). Thus, our data are consistent with the concept that intact p53 function, in the setting of oncogenic insult, can preserve partial HSC self-renewal capacity, and its loss in vivo is detrimental to HSC viability when accompanied by defects in cell cycle control mechanisms. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Ganoderic Acid A Promotes Amyloid-β Clearance (In Vitro) and Ameliorates Cognitive Deficiency in Alzheimer’s Disease (Mouse Model) Through Autophagy Induced by Activating Axl

2021 ◽  
Vol 22 (11) ◽  
pp. 5559
Author(s):  
Li-Feng-Rong Qi ◽  
Shuai Liu ◽  
Yu-Ci Liu ◽  
Ping Li ◽  
Xiaojun Xu
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Β ◽  
Microglial Cells ◽  
Confocal Laser ◽  
Ganoderic Acid ◽  
Aβ Clearance ◽  
Cognitive Deficiency ◽  
Ad Mouse Model

Alzheimer’s disease (AD) is thought to be caused by amyloid-β (Aβ) accumulation in the central nervous system due to deficient clearance. The aim of the present study was to investigate the effect of ganoderic acid A (GAA) on Aβ clearance in microglia and its anti-AD activity. Aβ degradation in BV2 microglial cells was determined using an intracellular Aβ clearance assay. GAA stimulated autophagosome formation via the Axl receptor tyrosine kinase (Axl)/RAC/CDC42-activated kinase 1 (Pak1) pathway was determined by Western blot analyses, and fluorescence-labeled Aβ42 was localized in lysosomes in confocal laser microscopy images. The in vivo anti-AD activity of GAA was evaluated by object recognition and Morris water maze (MWM) tests in an AD mouse model following intracerebroventricular injection of aggregated Aβ42. The autophagy level in the hippocampus was assayed by immunohistochemical assessment against microtubule-associated proteins 1A/1B light-chain 3B (LC3B). Intracellular Aβ42 levels were significantly reduced by GAA treatment in microglial cells. Additionally, GAA activated autophagy according to increased LC3B-II levels, with this increased autophagy stimulated by upregulating Axl and Pak1 phosphorylation. The effect of eliminating Aβ by GAA through autophagy was reversed by R428, an Axl inhibitor, or IPA-3, a Pak1 inhibitor. Consistent with the cell-based assay, GAA ameliorated cognitive deficiency and reduced Aβ42 levels in an AD mouse model. Furthermore, LC3B expression in the hippocampus was up-regulated by GAA treatment, with these GAA-specific effects abolished by R428. GAA promoted Aβ clearance by enhancing autophagy via the Axl/Pak1 signaling pathway in microglial cells and ameliorated cognitive deficiency in an AD mouse model.

scholarly journals Distinct Chronology of Neuronal Cell Cycle Re-Entry and Tau Pathology in the 3xTg-AD Mouse Model and Alzheimer's Disease Patients

2014 ◽  
Vol 43 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Alex C. Hradek ◽  
Hyun-Pil Lee ◽  
Sandra L. Siedlak ◽  
Sandy L. Torres ◽  
Wooyoung Jung ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Cell Cycle ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Neuronal Cell ◽  
Tau Pathology ◽  
Ad Mouse Model

scholarly journals Neuronal Cell Cycle Re-Entry Enhances Neuropathological Features in App NLF Knock-In Mice

2021 ◽  
pp. 1-20
Author(s):  
Tomás Barrett ◽  
Katherine A. Stangis ◽  
Takashi Saito ◽  
Takaomi Saido ◽  
Kevin H.J. Park
Keyword(s):  
Cell Cycle ◽  
Mouse Model ◽  
Dna Damage Response ◽  
Neuronal Cell ◽  
Leukocyte Infiltration ◽  
Pathogenic Role ◽  
Aberrant Cell ◽  
Damage Response ◽  
Ad Mouse Model

Background: Aberrant cell cycle re-entry is a well-documented process occurring early in Alzheimer’s disease (AD). This is an early feature of the disease and may contribute to disease pathogenesis. Objective: To assess the effect of forced neuronal cell cycle re-entry in mice expressing humanized Aβ, we crossed our neuronal cell cycle re-entry mouse model with App NLF knock-in (KI) mice. Methods: Our neuronal cell cycle re-entry (NCCR) mouse model is bitransgenic mice heterozygous for both Camk2a-tTA and TRE-SV40T. The NCCR mice were crossed with App NLF KI mice to generate NCCR-App NLF animals. Using this tet-off system, we triggered NCCR in our animals via neuronal expression of SV40T starting at 1 month of age. The animals were examined at the following time points: 9, 12, and 18 months of age. Various neuropathological features in our mice were evaluated by image analysis and stereology on brain sections stained using either immunofluorescence or immunohistochemistry. Results: We show that neuronal cell cycle re-entry in humanized Aβ plaque producing App NLF KI mice results in the development of additional AD-related pathologies, namely, pathological tau, neuroinflammation, brain leukocyte infiltration, DNA damage response, and neurodegeneration. Conclusion: Our findings show that neuronal cell cycle re-entry enhances AD-related neuropathological features in App NLF mice and highlight our unique AD mouse model for studying the pathogenic role of aberrant cell cycle re-entry in AD.

scholarly journals Oral Administration of Gintonin Protects the Brains of Mice against Aβ-Induced Alzheimer Disease Pathology: Antioxidant and Anti-Inflammatory Effects

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Muhammad Ikram ◽  
Min Gi Jo ◽  
Tae Ju Park ◽  
Min Woo Kim ◽  
Ibrahim Khan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mouse Model ◽  
Amyloid Β ◽  
Microglial Cells ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Protective Effects ◽  
Biochemical Tests ◽  
Proinflammatory Mediators ◽  
Ad Mouse Model

The study was aimed at analyzing the protective effects of gintonin in an amyloid beta- (Aβ-) induced Alzheimer’s disease (AD) mouse model. For the development of the Aβ-induced AD mouse model, the amyloid-β (Aβ1-42) peptide was stereotaxically injected into the brains of mice. Subsequently, gintonin was administered at a dose of 100 mg/kg/day/per oral (p.o) for four weeks daily, and its effects were evaluated by using western blotting, fluorescence analysis of brain sections, biochemical tests, and memory-related behavioral evaluations. To elucidate the effects of gintonin at the mechanistic level, the activation of endogenous antioxidant mechanisms, as well as the activation of astrocytes, microglia, and proinflammatory mediators such as nuclear factor erythroid 2-related factor 2 (NRF-2) and heme oxygenase-1 (HO-1), was evaluated. In addition, microglial cells (BV-2 cells) were used to analyze the effects of gintonin on microglial activation and signaling mechanisms. Collectively, the results suggested that gintonin reduced elevated oxidative stress by improving the expression of NRF-2 and HO-1 and thereby reducing the generation of reactive oxygen species (ROS) and lipid peroxidation (LPO). Moreover, gintonin significantly suppressed activated microglial cells and inflammatory mediators in the brains of Aβ-injected mice. Our findings also indicated improved synaptic and memory functions in the brains of Aβ-injected mice after treatment with gintonin. These results suggest that gintonin may be effective for relieving AD symptoms by regulating oxidative stress and inflammatory processes in a mouse model of AD. Collectively, the findings of this preclinical study highlight and endorse the potential, multitargeted protective effects of gintonin against AD-associated oxidative damage, neuroinflammation, cognitive impairment, and neurodegeneration.

scholarly journals BACE1 SUMOylation increases its stability and escalates the protease activity in Alzheimer’s disease

2018 ◽  
Vol 115 (15) ◽  
pp. 3954-3959 ◽  
Author(s):  
Jian Bao ◽  
Min Qin ◽  
Yacoubou Abdoul Razak Mahaman ◽  
Bin Zhang ◽  
Fang Huang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Protease Activity ◽  
Senile Plaque ◽  
Critical Role ◽  
Wild Type ◽  
Rate Limiting ◽  
Aβ Production ◽  
Ad Mouse Model

Amyloid beta (Aβ) is a major pathological marker in Alzheimer’s disease (AD), which is principally regulated by the rate-limiting β-secretase (i.e., BACE1) cleavage of amyloid precursor protein (APP). However, how BACE1 activity is posttranslationally regulated remains incompletely understood. Here, we show that BACE1 is predominantly SUMOylated at K501 residue, which escalates its protease activity and stability and subsequently increases Aβ production, leading to cognitive defect seen in the AD mouse model. Compared with a non-SUMOylated K501R mutant, injection of wild-type BACE1 significantly increases Aβ production and triggers cognitive dysfunction. Furthermore, overexpression of wild-type BACE1, but not non-SUMOylated K501R mutant, facilitates senile plaque formation and aggravates the cognitive deficit seen in the APP/PS1 AD mouse model. Together, our data strongly suggest that K501 SUMOylation on BACE1 plays a critical role in mediating its stability and enzymatic activity.

scholarly journals The MAO Inhibitor Tranylcypromine Alters LPS- and Aβ-Mediated Neuroinflammatory Responses in Wild-type Mice and a Mouse Model of AD

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1982
Author(s):  
HyunHee Park ◽  
Kyung-Min Han ◽  
Hyongjun Jeon ◽  
Ji-Soo Lee ◽  
Hyunju Lee ◽  
...  
Keyword(s):  
Mouse Model ◽  
Proinflammatory Cytokine ◽  
Microglial Activation ◽  
Microglial Cells ◽  
Wild Type ◽  
Mao Inhibitor ◽  
Cytokine Levels ◽  
Bv2 Microglial Cells

Monoamine oxidase (MAO) has been implicated in neuroinflammation, and therapies targeting MAO are of interest for neurodegenerative diseases. The small-molecule drug tranylcypromine, an inhibitor of MAO, is currently used as an antidepressant and in the treatment of cancer. However, whether tranylcypromine can regulate LPS- and/or Aβ-induced neuroinflammation in the brain has not been well-studied. In the present study, we found that tranylcypromine selectively altered LPS-induced proinflammatory cytokine levels in BV2 microglial cells but not primary astrocytes. In addition, tranylcypromine modulated LPS-mediated TLR4/ERK/STAT3 signaling to alter neuroinflammatory responses in BV2 microglial cells. Importantly, tranylcypromine significantly reduced microglial activation as well as proinflammatory cytokine levels in LPS-injected wild-type mice. Moreover, injection of tranylcypromine in 5xFAD mice (a mouse model of AD) significantly decreased microglial activation but had smaller effects on astrocyte activation. Taken together, our results suggest that tranylcypromine can suppress LPS- and Aβ-induced neuroinflammatory responses in vitro and in vivo.

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