Pathological tau aggregates form distinct polymorphic species across diseases and even across Alzheimer's disease (AD) patients. However, tau aggregate polymorphism across the apolipoprotein E isoform Show more
Pathological tau aggregates form distinct polymorphic species across diseases and even across Alzheimer's disease (AD) patients. However, tau aggregate polymorphism across the apolipoprotein E isoforms (APOE ε2, ε3, ε4), the strongest predictors of late-onset AD development, is unknown. This study assessed the conformational and bioactivity properties of tau oligomers from 14 patients with varying APOE genotypes. Tau oligomers differ in proteolytic stability and cleavage site profiles across the APOE isoforms, indicating conformationally distinct polymorphs. APOE isoform-associated tau oligomers affect synaptic plasticity differently, with ε4-associated oligomers having the highest potency and strongest impact on synaptic functioning. Bioactivity assays reveal that ε4-associated oligomers demonstrate particularly high seeding activity. Interestingly, tau oligomer synaptotoxicity and seeding activity are independent characteristics. The APOE isoforms are associated with distinct tau oligomer polymorphs with varying bioactivity, underscoring the importance of considering APOE status when generating AD therapies. Polymorph-specific targeting of pathological tau species could provide a novel method of combating AD. Conformational and bioactivity distinctions of tau oligomers have not yet been investigated across the APOE isoforms (ε2, ε3, ε4). Tau oligomers differ in conformational properties across the APOE isoforms. APOE ε4-relevant tau oligomers strongly impair synaptic plasticity and demonstrate high tau seeding activity. APOE ε4-relevant tau oligomers exist as a particularly toxic species, making them an ideal target for tau-based AD therapies. Show less
Background Heart attacks and stroke often result from occlusive thrombi following the rupture of vulnerable atherosclerotic plaques. Vascular smooth muscle cells (VSMCs) play a pivotal role in plaque Show more
Background Heart attacks and stroke often result from occlusive thrombi following the rupture of vulnerable atherosclerotic plaques. Vascular smooth muscle cells (VSMCs) play a pivotal role in plaque vulnerability because of their switch towards a proinflammatory/macrophage-like phenotype when in the context of atherosclerosis. The prometastatic transcription factor Slug/Snail2 is a critical regulator of cell phenotypic transition. Here, we aimed to investigate the role of Slug in the transdifferentiation process of VSMCs occurring during atherogenesis. Methods and Results In rat and human primary aortic smooth muscle cells, Slug protein expression is strongly and rapidly increased by platelet-derived growth factor-BB (PDGF-BB). PDGF-BB increases Slug protein without affecting mRNA levels indicating that this growth factor stabilizes Slug protein. Immunocytochemistry and subcellular fractionation experiments reveal that PDGF-BB triggers a rapid accumulation of Slug in VSMC nuclei. Using pharmacological tools, we show that the PDGF-BB-dependent mechanism of Slug stabilization in VSMCs involves the extracellular signal-regulated kinase 1/2 pathway. Immunohistochemistry experiments on type V and type VI atherosclerotic lesions of human carotids show smooth muscle-specific myosin heavy chain-/Slug-positive cells surrounding the prothrombotic lipid core. In VSMCs, Slug siRNAs inhibit prostaglandin E2 secretion and prevent the inhibition of cholesterol efflux gene expression mediated by PDGF-BB, known to be involved in plaque vulnerability and/or thrombogenicity. Conclusions Our results highlight, for the first time, a role of Slug in aortic smooth muscle cell transdifferentiation and enable us to consider Slug as an actor playing a role in the atherosclerotic plaque progression towards a life-threatening phenotype. This also argues for common features between acute cardiovascular events and cancer. Show less