Alzheimer's disease (AD) and other age-related disorders associated with demyelination exhibit sex differences. In this work, we used single-nuclei transcriptomics to dissect the contributions of sex chromosomes and gonads in demyelination and AD. In a mouse model of demyelination, we identified the roles of sex chromosomes and gonads in modifying microglia and oligodendrocyte responses before and after myelin loss.
View Article and Find Full Text PDFWe previously showed that the anticancer drug imatinib mesylate (IMT, trade name: Gleevec) and a chemically distinct compound, DV2-103 (a kinase-inactive derivative of the potent Abl and Src kinase inhibitor, PD173955) lower Aβ levels at low micromolar concentrations primarily through a lysosome-dependent mechanism that renders APP less susceptible to proteolysis by BACE1 without directly inhibiting BACE1 enzymatic activity, or broadly inhibiting the processing of other BACE1 substrates. Additionally, IMT indirectly inhibits γ-secretase and stimulates autophagy, and thus may decrease Aβ levels through multiple pathways. In two recent studies we demonstrated similar effects on APP metabolism caused by derivatives of IMT and DV2-103.
View Article and Find Full Text PDFThe prefrontal cortex (PFC) is a key neural node mediating behavioral responses to stress and the actions of ketamine, a fast-acting antidepressant. The molecular mechanisms underlying these processes, however, are not fully understood. Our recent study revealed a pivotal role of hippocampal Ahnak as a regulator of cellular and behavioral adaptations to chronic stress.
View Article and Find Full Text PDFThe Christchurch mutation (R136S) on the () gene is associated with low tau pathology and slowdown of cognitive decline despite the causal mutation and high levels of amyloid beta pathology in the carrier. However, the molecular effects enabling mutation to confer protection remain unclear. Here, we replaced mouse Apoe with wild-type human or on a tauopathy background.
View Article and Find Full Text PDFNeurons from layer II of the entorhinal cortex (ECII) are the first to accumulate tau protein aggregates and degenerate during prodromal Alzheimer's disease. Gaining insight into the molecular mechanisms underlying this vulnerability will help reveal genes and pathways at play during incipient stages of the disease. Here, we use a data-driven functional genomics approach to model ECII neurons in silico and identify the proto-oncogene DEK as a regulator of tau pathology.
View Article and Find Full Text PDFThe strongest risk factors for Alzheimer's disease (AD) include the χ4 allele of apolipoprotein E (APOE), the variant of triggering receptor expressed on myeloid cells 2 (TREM2), and female sex. Here, we combine and ( ) in female tauopathy mice to identify the pathways activated when AD risk is the strongest, thereby highlighting disease-causing mechanisms. We find that the variant induces neurodegeneration in female mice without impacting hippocampal tau load.
View Article and Find Full Text PDFAlzheimer's disease (AD) is a debilitating neurodegenerative disorder characterized by the accumulation of β-amyloid (Aβ), C99, and Tau in vulnerable areas of the brain. Despite extensive research, current strategies to lower Aβ levels have shown limited efficacy in slowing the cognitive decline associated with AD. Recent findings suggest that C99 may also play a crucial role in the pathogenesis of AD.
View Article and Find Full Text PDFDNA sensing is a pivotal component of the innate immune system that is responsible for detecting mislocalized DNA and triggering downstream inflammatory pathways. Among the DNA sensors, cyclic GMP-AMP synthase (cGAS) is a primary player in detecting cytosolic DNA, including foreign DNA from pathogens and self-DNA released during cellular damage, culminating in a type I interferon (IFN-I) response through stimulator of interferon genes (STING) activation. IFN-I cytokines are essential in mediating neuroinflammation, which is widely observed in CNS injury, neurodegeneration, and aging, suggesting an upstream role for the cGAS DNA sensing pathway.
View Article and Find Full Text PDFPathological hallmarks of Alzheimer's disease (AD) precede clinical symptoms by years, indicating a period of cognitive resilience before the onset of dementia. Here, we report that activation of cyclic GMP-AMP synthase (cGAS) diminishes cognitive resilience by decreasing the neuronal transcriptional network of myocyte enhancer factor 2c (MEF2C) through type I interferon (IFN-I) signaling. Pathogenic tau activates cGAS and IFN-I responses in microglia, in part mediated by cytosolic leakage of mitochondrial DNA.
View Article and Find Full Text PDFMixed Lineage Kinase 3 (MLK3) is a viable target for neoplastic diseases; however, it is unclear whether its activators or inhibitors can act as anti-neoplastic agents. We reported that the MLK3 kinase activity was higher in triple-negative (TNBC) than in hormone receptor-positive human breast tumors, where estrogen inhibited MLK3 kinase activity and provided a survival advantage to ER breast cancer cells. Herein, we show that in TNBC, the higher MLK3 kinase activity paradoxically promotes cancer cell survival.
View Article and Find Full Text PDFThe hemizygous R47H variant of triggering receptor expressed on myeloid cells 2 (), a microglia-specific gene in the brain, increases risk for late-onset Alzheimer’s disease (AD). Using transcriptomic analysis of single nuclei from brain tissues of patients with AD carrying the R47H mutation or the common variant (CV)–, we found that R47H-associated microglial subpopulations had enhanced inflammatory signatures reminiscent of previously identified disease-associated microglia (DAM) and hyperactivation of AKT, one of the signaling pathways downstream of TREM2. We established a tauopathy mouse model with heterozygous knock-in of the human with the R47H mutation or CV and found that R47H induced and exacerbated TAU-mediated spatial memory deficits in female mice.
View Article and Find Full Text PDFMAP4K4 is a Ste20 member and reported to play important roles in various pathologies, including in cancer. However, the mechanism by which MAP4K4 promotes pancreatic cancer is not fully understood. It is suggested that MAP4K4 might function as a cancer promoter via specific downstream target(s) in an organ-specific manner.
View Article and Find Full Text PDFThe transcription factor Glioma-Associated Oncogene Homolog 1 (GLI1) is activated by sonic hedgehog (SHH) cascade and is an established driver of pancreatic ductal adenocarcinoma (PDAC). However, therapies targeting upstream hedgehog signaling have shown little to no efficacy in clinical trials. Here, we identify Mixed Lineage Kinase 3 (MLK3) as a druggable regulator of oncogenic GLI1.
View Article and Find Full Text PDFTafamidis, , a potent transthyretin kinetic stabilizer, weakly inhibits the γ-secretase enzyme . We have synthesized four amide derivatives of . These compounds reduce production of the Aβ peptide in N2a695 cells but do not inhibit the γ-secretase enzyme in cell-free assays.
View Article and Find Full Text PDFAmyloid-beta peptides generated by β-secretase- and γ-secretase-mediated successive cleavage of amyloid precursor protein are believed to play a causative role in Alzheimer's disease. Thus, reducing amyloid-beta generation by modulating γ-secretase remains a promising approach for Alzheimer's disease therapeutic development. Here, we screened fruit extracts of Ait.
View Article and Find Full Text PDFBackground: Parvalbumin (PV)-expressing interneurons are important for cognitive and emotional behaviors. These neurons express high levels of p11, a protein associated with depression and action of antidepressants.
Methods: We characterized the behavioral response to subthreshold stress in mice with conditional deletion of p11 in PV cells.
Mixed lineage kinase 3 (MLK3), also known as MAP3K11, was initially identified in a megakaryocytic cell line and is an emerging therapeutic target in cancer, yet its role in immune cells is not known. Here, we report that loss or pharmacological inhibition of MLK3 promotes activation and cytotoxicity of T cells. MLK3 is abundantly expressed in T cells, and its loss alters serum chemokines, cytokines, and CD28 protein expression on T cells and its subsets.
View Article and Find Full Text PDFCompound , DV2-103, is a kinase inactive analogue of a potent Abl1/Src kinase inhibitor, PD173955, . Both compounds, and , are known to reduce production of beta amyloid (Aβ) peptide in cells and animal models. We have now prepared and evaluated a series of PD-173955 analogues, several of which reduced Aβ production potently.
View Article and Find Full Text PDFImatinib mesylate, 1a, inhibits production of β-amyloid (Aβ) peptides both in cells and in animal models. It reduces both the β-secretase and γ-secretase cleavages of the amyloid precursor protein (APP) and mediates a synergistic effect, when combined with a β-secretase inhibitor, BACE IV. Toward developing more potent brain-permeable leads, we have synthesized and evaluated over 75 1a-analogues.
View Article and Find Full Text PDFAlzheimer's disease (AD) is characterized by accumulation of the β-amyloid peptide (Aβ), which is generated through sequential proteolysis of the amyloid precursor protein (APP), first by the action of β-secretase, generating the β-C-terminal fragment (βCTF), and then by the Presenilin 1 (PS1) enzyme in the γ-secretase complex, generating Aβ. γ-Secretase is an intramembranous protein complex composed of Aph1, Pen2, Nicastrin, and Presenilin 1. Although it has a central role in the pathogenesis of AD, knowledge of the mechanisms that regulate PS1 function is limited.
View Article and Find Full Text PDFMixed Lineage Kinase 3 (MLK3), also called as MAP3K11 is a tightly regulated MAP3K member but its cellular function is still not fully understood. Earlier we reported post-translational regulation of MLK3 by estrogen (E2) that inhibited the kinase activity and favored survival of ER+ breast cancer cells. Here we report that MLK3 is also transcriptionally downregulated by E2 in ER+ breast cancer cells.
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