Reelin operates through canonical and non-canonical pathways that mediate several aspects of brain development and function. Reelin's dimeric central fragment (CF), generated through proteolytic cleavage, is required for the lipoprotein-receptor-dependent canonical pathway activation. Here, we analyze the signaling properties of a variety of Reelin fragments and measure the differential binding affinities of monomeric and dimeric CF fragments to lipoprotein receptors to investigate the mode of canonical signal activation. We also present the cryoelectron tomography-solved dimeric structure of Reelin CF and support it using several other biophysical techniques. Our findings suggest that Reelin CF forms a covalent parallel dimer with some degree of flexibility between the two protein chains. As a result of this conformation, Reelin binds to lipoprotein receptors in a manner inaccessible to its monomeric form and is capable of stimulating canonical pathway signaling.
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http://dx.doi.org/10.1016/j.str.2021.05.012 | DOI Listing |
Alzheimers Dement
December 2024
University of Michigan, Ann Arbor, MI, USA.
Background: Inhibitory interneurons normally regulate neural networks underlying memory and cognition, but are disrupted in Alzheimer's disease. Proper interneuron activity reduces amyloid-beta, whereas hyperexcitability elevates amyloid levels. Still, the underlying pathologic processes mediating interneuron dysfunction remain unknown.
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December 2024
Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA.
Background: Alzheimer's disease (AD) hallmarks are amyloid plaques and tau tangles. APOE and TREM2 are the strongest genetic risk factors for AD. Triggering receptor expressed on myeloid cells 2 (TREM2) is increasingly recognized to play a central role in amyloid beta clearance and microglia activation in AD.
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December 2024
Georgia Institute of Technology, Atlanta, GA, USA.
Background: Mitogen activated protein kinase (MAPK) signaling is a critical regulator of microglial phenotype, including phagocytic function, cytokine expression, and motility, among others. Importantly, both canonical and non-canonical MAPK signaling is directly activated by RTKs, including Interestingly, CSF1R, is activated by two agonists, CSF1 and IL-34, which have been shown to activate the receptor in different ways that can lead to However, little is known about how the affect microglial MAPK signaling, and whether their effects are dependent on disease state/Aβ exposure. In this study, we hypothesized that IL-34 and CSF-1 elicit distinct patterns of MAPK signaling activation in microglia and MAPK activation would be dependent on whether the cells were exposed to Aβ.
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December 2024
Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Background: The apolipoprotein E (APOE) ε4 allele is the strongest genetic risk factor for Alzheimer's disease (AD), increasing risk from 3-12-fold relative to the common ε3 allele. Seminal studies have revealed that age-related changes in blood-CNS communication regulate cognitive function. More recently, youth-associated blood-borne proteins revitalize the aged brain, improving hippocampal function and increasing adult neurogenesis and dendritic spine plasticity.
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December 2024
Physiopathology in Aging Laboratory (LIM-22), University of São Paulo Medical School, São Paulo, São Paulo, Brazil.
Background: Understanding the molecular mechanisms underlying selective neuronal vulnerability is crucial for developing effective treatments for Alzheimer's disease (AD). Our group has shown that RORB/CDH9-positive excitatory neurons in the entorhinal cortex (EC) display selective vulnerability as early as Braak stage (BB) 2. However, not all RORB/CDH9-positive neurons are vulnerable.
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