Biology subjects

Szatmari, E. M.

Publications and source records attributed to Szatmari, E. M..

4 recordsLinked to original sources

bioRxiv2025

Lack of ADAP1/Centaurin-α1 Ameliorates Cognitive Impairment and Neuropathological Hallmarks in a Mouse Model of Alzheimer's Disease

ArfGAP, with dual PH domain-containing protein 1/Centaurin-1 (ADAP1CentA1), is a brain-enriched and highly conserved Arf6 GTPase-activating and Ras-anchoring protein. ADAP1 is involved in dendritic outgrowth and arborization, synaptogenesis, and axonal polarization by regulating the dynamics of the actin cytoskeleton. An increased level of ADAP1 and its association with amyloid plaques in the human Alzheimers disease (AD) brain suggest a role for this protein in AD progression. To understand the role of ADAP1/CentA1 in neurodegeneration, we crossbred CentA1 KO mice with the hAPP-J20 mouse model of AD (J20 x CentA1 KO). We then evaluated the gene expression profile and the behavioral and neuropathological hallmarks of AD to determine the impact of eliminating ADAP1/CentA1 expression on AD-related phenotypes. Spatial memory assessed by the Morris Water Maze test showed significant impairment in J20 mice, which was rescued by the deletion of CentA1. Neuropathological hallmarks of AD, such as deposits of amyloid plaques and neuroinflammation, were significantly reduced in the AD model mice with CentA1 KO background. To identify potential mediators of AD phenotype rescue, we analyzed differentially expressed genes (DEGs) between genotypes, by employing transcriptome profiling with Nanostring nCounter Neuropathology and Neuroinflammation panels. We found significant upregulation of genes associated with apoptosis and gliosis in the brain of J20 mice. However, many of these genes, including the pro-apoptotic gene, Bid, were restored in the brains of J20 x CentA1 KO mice compared to J20 mice. In summary, our data indicate that CentA1 is required for the progression of AD phenotypes and that targeting CentA1 signaling at mitochondria might have therapeutic potential for AD prevention or treatment. SIGNIFICANCE STATEMENTADAP1/Centaurin-1 (CentA1) is highly enriched in the brain and increased CentA1 level has been linked to Alzheimers disease (AD). However, the precise role of ADAP1 in the pathogenesis of AD is poorly understood. We found that genetic deletion of CentA1 in the AD model mice rescues the pathological hallmarks of AD, including loss of dendritic spines in the hippocampus, amyloid plaque deposition, neuroinflammation and spatial memory deficits. Transcriptome analysis of forebrain samples using NanoString nCounter panels for 880 genes, identified the pro-apoptotic protein, Bid, with significantly reduced expression in the J20 mice on ADAP1 KO background. These findings point towards a role of ADAP1 in the activation of the mitochondrial pathways of death associated with the progression of neurodegeneration.

neuroscience↗

bioRxiv2022

Disinhibition of Rab10 gates AMPAR insertion and spine enlargement during long-term potentiation

Rab-dependent membrane trafficking is critical for changing the structure and function of dendritic spines during synaptic plasticity. Here, we developed highly sensitive sensors to monitor Rab protein activity in single dendritic spines undergoing structural long-term potentiation (sLTP) in rodent organotypic hippocampal slices. During sLTP, Rab10 was persistently inactivated (>30 min) in the stimulated spines, whereas Rab4 was transiently activated over [~]5 min. Inhibiting or deleting Rab10 enhanced sLTP, electrophysiological LTP and AMPA receptor (AMPAR) trafficking during sLTP. In contrast, disrupting Rab4 impaired sLTP only in the first few minutes, and decreased AMPAR trafficking during sLTP. Thus, our results suggest that Rab10 and Rab4 oppositely regulate AMPAR trafficking during sLTP, and inactivation of Rab10 signaling facilitates the induction of LTP and associated spine structural plasticity.

neuroscience↗

bioRxiv2022

CRY-BARs: Versatile light-gated molecular tools for the remodeling of membrane architectures

BAR (Bin, Amphiphysin and Rvs) protein domains are responsible for the generation of membrane curvature and represent a critical mechanical component of cellular functions. Thus, BAR domains have great potential as components of membrane-remodeling tools for cell biologists. In this work, we describe the design and implementation of a family of versatile light-gated I-BAR domain containing tools ( CRY-BARs) with applications in the remodeling of membrane architectures and the control of cellular dynamics. By taking advantage of the intrinsic membrane binding propensity of the I-BAR domain, CRY-BARs can be used for spatial and temporal control of cellular processes that require induction of membrane protrusions. Using cell lines and primary neuron cultures, we demonstrate that the CRY-BAR optogenetic tool reports membrane dynamic changes associated with cellular activity. Moreover, we provide evidence that Ezrin acts as a relay between the plasma membrane and the actin cytoskeleton and therefore is an important mediator of switch function. Overall, CRY-BARs hold promise as a useful addition to the optogenetic toolkit to study membrane remodeling in live cells.

cell biology↗

bioRxiv2019

CofActor: A light and redox-gated optogenetic clustering tool to study abnormal cytoskeletal dynamics in stressed cells

The biochemical hallmarks of neurodegenerative diseases (neural fibrils, clumps, and tangles; heightened reactive oxygen species (ROS); cofilin-actin rods) have presented numerous challenges for development of in vivo diagnostic tools (1-7). Biomarkers such as amyloid beta (A{beta}) fibrils and Tau tangles in Alzheimers Disease (AD) are only accessible via invasive cerebrospinal fluid assay for peptide mass fingerprinting or post-mortem diagnosis (8-11), while ROS can be fleeting and thus challenging to monitor in vivo (12-15). While remaining a challenge for in vivo detection, the unique protein-protein interactions underlying these disease-specific biomarkers also present rich opportunities for the engineering of in vitro pathology-sensitive biosensors and bioactuators. These tools can be useful for the investigation of critical, early stage events in neurodegenerative diseases in both cellular and animal models (16, 17), while potentially leading to advanced detection reagents with clinical applications. In this report, we describe a light and redox-gated protein switch inspired by the phenomenon of cofilin-actin rod formation, which occurs in stressed neurons in the AD brain and following brain ischemia (18). By coupling the redox-sensitive interaction of cofilin and actin with the light responsive Cry2-CIB blue light switch, we accomplish both light- and ROS-gated control of this interaction. The resulting switch is referred to as the "CofActor" system. Site-directed mutagenesis of both cofilin and actin partners demonstrate which residues are critical for sustaining or abrogating the light and redox gated response. Furthermore, switch response varies depending on whether oxidative stress is generated via glycolytic inhibition or a combination of glycolytic inhibition and azide-induced oxidative stress. Finally, light and redox gated switch function was demonstrated in cultured hippocampal neurons. As a dual input biosensor, CofActor holds promise for the tracking of early stage events in neurodegeneration and the investigation of actin-binding protein interactions under oxidative stress.

neuroscience↗