The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
Ruth Furukawa - One of the best experts on this subject based on the ideXlab platform.
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de novo actin polymerization is required for model Hirano Body formation in dictyostelium
Biology Open, 2016Co-Authors: Yun Dong, Sonbol Shahidsalles, Dan Sherling, Nathan Fechheimer, Nathan Iyer, Lance Wells, Marcus Fechheimer, Ruth FurukawaAbstract:Hirano bodies are eosinophilic, actin-rich inclusions found in autopsied brains in numerous neurodegenerative diseases. The mechanism of Hirano Body formation is unknown. Mass spectrometry analysis was performed to identify proteins from partially purified model Hirano bodies from Dictyostelium This analysis identified proteins primarily belonging to ribosomes, proteasomes, mitochondria and cytoskeleton. Profilin, Arp/2/3 and WASH identified by mass spectrometry were found to colocalise with model Hirano bodies. Due to their roles in actin regulation, we selected these proteins for further investigation. Inhibition of the Arp2/3 complex by CK666 prevented formation of model Hirano bodies. Since Arp2/3 activation occurs via the WASH or WAVE complex, we next investigated how these proteins affect Hirano Body formation. Whereas model Hirano bodies could form in WASH-deficient cells, they failed to form in cells lacking HSPC300, a member of the WAVE complex. We identified other proteins required for Hirano Body formation that include profilin and VASP, an actin nucleation factor. In the case of VASP, both its G- and F-actin binding domains were required for model Hirano Body formation. Collectively, our results indicate that de novo actin polymerization is required to form model Hirano bodies.
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Hirano Body expression impairs spatial working memory in a novel mouse model
Acta neuropathologica communications, 2014Co-Authors: Matthew Furgerson, Marcus Fechheimer, Jason K Clark, Jonathon D Crystal, John J Wagner, Ruth FurukawaAbstract:Hirano bodies are actin-rich intracellular inclusions found in the brains of patients with neurodegenerative conditions such as Alzheimer's disease or frontotemporal lobar degeneration-tau. While Hirano Body ultrastructure and protein composition have been well studied, little is known about the physiological function of Hirano bodies in an animal model system. Utilizing a Cre/Lox system, we have generated a new mouse model which develops an age-dependent increase in the number of model Hirano bodies present in both the CA1 region of the hippocampus and frontal cortex. These mice develop normally and experience no overt neuron loss. Mice presenting model Hirano bodies have no abnormal anxiety or locomotor activity as measured by the open field test. However, mice with model Hirano bodies develop age-dependent impairments in spatial working memory performance assessed using a delayed win-shift task in an 8-arm radial maze. Synaptic transmission, short-term plasticity, and long-term plasticity was measured in the CA1 region from slices obtained from both the ventral and dorsal hippocampus in the same mice whose spatial working memory was assessed. Baseline synaptic responses, paired pulse stimulation and long-term potentiation measurements in the ventral hippocampus were indistinguishable from control mice. In contrast, in the dorsal hippocampus, synaptic transmission at higher stimulus intensities were suppressed in 3 month old mice with Hirano bodies as compared with control mice. In addition, long-term potentiation was enhanced in the dorsal hippocampus of 8 month old mice with Hirano bodies, concurrent with observed impairment of spatial working memory. Finally, an inflammatory response was observed at 8 months of age in mice with Hirano bodies as assessed by the presence of reactive astrocytes. This study shows that the presence of model Hirano bodies initiates an inflammatory response, alters hippocampal synaptic responses, and impairs spatial working memory in an age-dependent manner. This suggests that Hirano bodies may promote disease progression. This new model mouse provides a tool to investigate how Hirano bodies interact with other pathologies associated with Alzheimer's disease. Hirano bodies likely play a complex and region specific role in the brain during neurodegenerative disease progression.
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requirements for Hirano Body formation
Eukaryotic Cell, 2014Co-Authors: Paul Griffin, Ruth Furukawa, Cleveland Piggott, Andrew Maselli, Marcus FechheimerAbstract:Hirano bodies are paracrystalline F-actin-rich structures associated with diverse conditions, including neurodegeneration and aging. Generation of model Hirano bodies using altered forms of Dictyostelium 34-kDa actin-bundling protein allows studies of their physiological function and mechanism of formation. We describe a novel 34-kDa protein mutant, E60K, with a point mutation within the inhibitory domain of the 34-kDa protein. Expression of E60K in Dictyostelium induces the formation of model Hirano bodies. The E60K protein has activated actin binding and is calcium regulated, unlike other forms of the 34-kDa protein that induce Hirano bodies and that have activated actin binding but lack calcium regulation. Actin filaments in the presence of E60K in vitro show enhanced resistance to disassembly induced by latrunculin B. Actin filaments in model Hirano bodies are also protected from latrunculin-induced depolymerization. We used nocodazole and blebbistatin to probe the role of the microtubules and myosin II, respectively, in the formation of model Hirano bodies. In the presence of these inhibitors, model Hirano bodies can form but are smaller than controls at early times of formation. The ultrastructure of model Hirano bodies did not reveal any major difference in structure and organization in the presence of inhibitors. In summary, these results support the conclusion that formation of model Hirano bodies is promoted by gain-of-function actin filament bundling, which enhances actin filament stabilization. Microtubules and myosin II contribute to but are not required for formation of model Hirano bodies.
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Model Hirano Bodies do not protect against etoposide-induced cell death.
2012Co-Authors: Matthew Furgerson, Marcus Fechheimer, Ruth FurukawaAbstract:H4 cells were transfected with CT-GFP to induce Hirano Body formation (check bars) or GFP (black bars) as a control. Expression of CT-GFP or GFP alone caused very low levels of cell death in the absence of etoposide. In the presence of 100 µM etoposide, cell death was significantly increased (***p
Marcus Fechheimer - One of the best experts on this subject based on the ideXlab platform.
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de novo actin polymerization is required for model Hirano Body formation in dictyostelium
Biology Open, 2016Co-Authors: Yun Dong, Sonbol Shahidsalles, Dan Sherling, Nathan Fechheimer, Nathan Iyer, Lance Wells, Marcus Fechheimer, Ruth FurukawaAbstract:Hirano bodies are eosinophilic, actin-rich inclusions found in autopsied brains in numerous neurodegenerative diseases. The mechanism of Hirano Body formation is unknown. Mass spectrometry analysis was performed to identify proteins from partially purified model Hirano bodies from Dictyostelium This analysis identified proteins primarily belonging to ribosomes, proteasomes, mitochondria and cytoskeleton. Profilin, Arp/2/3 and WASH identified by mass spectrometry were found to colocalise with model Hirano bodies. Due to their roles in actin regulation, we selected these proteins for further investigation. Inhibition of the Arp2/3 complex by CK666 prevented formation of model Hirano bodies. Since Arp2/3 activation occurs via the WASH or WAVE complex, we next investigated how these proteins affect Hirano Body formation. Whereas model Hirano bodies could form in WASH-deficient cells, they failed to form in cells lacking HSPC300, a member of the WAVE complex. We identified other proteins required for Hirano Body formation that include profilin and VASP, an actin nucleation factor. In the case of VASP, both its G- and F-actin binding domains were required for model Hirano Body formation. Collectively, our results indicate that de novo actin polymerization is required to form model Hirano bodies.
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Hirano Body expression impairs spatial working memory in a novel mouse model
Acta neuropathologica communications, 2014Co-Authors: Matthew Furgerson, Marcus Fechheimer, Jason K Clark, Jonathon D Crystal, John J Wagner, Ruth FurukawaAbstract:Hirano bodies are actin-rich intracellular inclusions found in the brains of patients with neurodegenerative conditions such as Alzheimer's disease or frontotemporal lobar degeneration-tau. While Hirano Body ultrastructure and protein composition have been well studied, little is known about the physiological function of Hirano bodies in an animal model system. Utilizing a Cre/Lox system, we have generated a new mouse model which develops an age-dependent increase in the number of model Hirano bodies present in both the CA1 region of the hippocampus and frontal cortex. These mice develop normally and experience no overt neuron loss. Mice presenting model Hirano bodies have no abnormal anxiety or locomotor activity as measured by the open field test. However, mice with model Hirano bodies develop age-dependent impairments in spatial working memory performance assessed using a delayed win-shift task in an 8-arm radial maze. Synaptic transmission, short-term plasticity, and long-term plasticity was measured in the CA1 region from slices obtained from both the ventral and dorsal hippocampus in the same mice whose spatial working memory was assessed. Baseline synaptic responses, paired pulse stimulation and long-term potentiation measurements in the ventral hippocampus were indistinguishable from control mice. In contrast, in the dorsal hippocampus, synaptic transmission at higher stimulus intensities were suppressed in 3 month old mice with Hirano bodies as compared with control mice. In addition, long-term potentiation was enhanced in the dorsal hippocampus of 8 month old mice with Hirano bodies, concurrent with observed impairment of spatial working memory. Finally, an inflammatory response was observed at 8 months of age in mice with Hirano bodies as assessed by the presence of reactive astrocytes. This study shows that the presence of model Hirano bodies initiates an inflammatory response, alters hippocampal synaptic responses, and impairs spatial working memory in an age-dependent manner. This suggests that Hirano bodies may promote disease progression. This new model mouse provides a tool to investigate how Hirano bodies interact with other pathologies associated with Alzheimer's disease. Hirano bodies likely play a complex and region specific role in the brain during neurodegenerative disease progression.
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requirements for Hirano Body formation
Eukaryotic Cell, 2014Co-Authors: Paul Griffin, Ruth Furukawa, Cleveland Piggott, Andrew Maselli, Marcus FechheimerAbstract:Hirano bodies are paracrystalline F-actin-rich structures associated with diverse conditions, including neurodegeneration and aging. Generation of model Hirano bodies using altered forms of Dictyostelium 34-kDa actin-bundling protein allows studies of their physiological function and mechanism of formation. We describe a novel 34-kDa protein mutant, E60K, with a point mutation within the inhibitory domain of the 34-kDa protein. Expression of E60K in Dictyostelium induces the formation of model Hirano bodies. The E60K protein has activated actin binding and is calcium regulated, unlike other forms of the 34-kDa protein that induce Hirano bodies and that have activated actin binding but lack calcium regulation. Actin filaments in the presence of E60K in vitro show enhanced resistance to disassembly induced by latrunculin B. Actin filaments in model Hirano bodies are also protected from latrunculin-induced depolymerization. We used nocodazole and blebbistatin to probe the role of the microtubules and myosin II, respectively, in the formation of model Hirano bodies. In the presence of these inhibitors, model Hirano bodies can form but are smaller than controls at early times of formation. The ultrastructure of model Hirano bodies did not reveal any major difference in structure and organization in the presence of inhibitors. In summary, these results support the conclusion that formation of model Hirano bodies is promoted by gain-of-function actin filament bundling, which enhances actin filament stabilization. Microtubules and myosin II contribute to but are not required for formation of model Hirano bodies.
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Model Hirano Bodies do not protect against etoposide-induced cell death.
2012Co-Authors: Matthew Furgerson, Marcus Fechheimer, Ruth FurukawaAbstract:H4 cells were transfected with CT-GFP to induce Hirano Body formation (check bars) or GFP (black bars) as a control. Expression of CT-GFP or GFP alone caused very low levels of cell death in the absence of etoposide. In the presence of 100 µM etoposide, cell death was significantly increased (***p
Gustavo Egea - One of the best experts on this subject based on the ideXlab platform.
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clearance of a Hirano Body like f actin aggresome generated by jasplakinolide
Autophagy, 2008Co-Authors: Francisco Lazarodieguez, Erwin Knecht, Gustavo EgeaAbstract:We have reported in a variety of mammalian cells the reversible formation of a filamentous actin (F-actin)-enriched aggresome generated by the actin toxin jasplakinolide (Lazaro-Dieguez et al., J Cell Sci 2008; 121:1415-25). Notably, this F-actin aggresome (FAG) resembles in many aspects the pathological Hirano Body, which frequently appears in some diseases such as Alzheimer's and alcoholism. Using selective inhibitors, we examined the molecular and subcellular mechanisms that participate in the clearance of the FAG. Chaperones, microtubules, proteasomes and autophagosomes all actively participate to eliminate the FAG. Here we compile and compare these results and discuss the involvement of each process. Because of its simplicity and high reproducibility, our cellular model could help to test pharmacological agents designed to interfere with the mechanisms involved in the clearance of intracellular bodies and, in particular, of those enriched in F-actin.
Francisco Lazarodieguez - One of the best experts on this subject based on the ideXlab platform.
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clearance of a Hirano Body like f actin aggresome generated by jasplakinolide
Autophagy, 2008Co-Authors: Francisco Lazarodieguez, Erwin Knecht, Gustavo EgeaAbstract:We have reported in a variety of mammalian cells the reversible formation of a filamentous actin (F-actin)-enriched aggresome generated by the actin toxin jasplakinolide (Lazaro-Dieguez et al., J Cell Sci 2008; 121:1415-25). Notably, this F-actin aggresome (FAG) resembles in many aspects the pathological Hirano Body, which frequently appears in some diseases such as Alzheimer's and alcoholism. Using selective inhibitors, we examined the molecular and subcellular mechanisms that participate in the clearance of the FAG. Chaperones, microtubules, proteasomes and autophagosomes all actively participate to eliminate the FAG. Here we compile and compare these results and discuss the involvement of each process. Because of its simplicity and high reproducibility, our cellular model could help to test pharmacological agents designed to interfere with the mechanisms involved in the clearance of intracellular bodies and, in particular, of those enriched in F-actin.
Paul Griffin - One of the best experts on this subject based on the ideXlab platform.
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requirements for Hirano Body formation
Eukaryotic Cell, 2014Co-Authors: Paul Griffin, Ruth Furukawa, Cleveland Piggott, Andrew Maselli, Marcus FechheimerAbstract:Hirano bodies are paracrystalline F-actin-rich structures associated with diverse conditions, including neurodegeneration and aging. Generation of model Hirano bodies using altered forms of Dictyostelium 34-kDa actin-bundling protein allows studies of their physiological function and mechanism of formation. We describe a novel 34-kDa protein mutant, E60K, with a point mutation within the inhibitory domain of the 34-kDa protein. Expression of E60K in Dictyostelium induces the formation of model Hirano bodies. The E60K protein has activated actin binding and is calcium regulated, unlike other forms of the 34-kDa protein that induce Hirano bodies and that have activated actin binding but lack calcium regulation. Actin filaments in the presence of E60K in vitro show enhanced resistance to disassembly induced by latrunculin B. Actin filaments in model Hirano bodies are also protected from latrunculin-induced depolymerization. We used nocodazole and blebbistatin to probe the role of the microtubules and myosin II, respectively, in the formation of model Hirano bodies. In the presence of these inhibitors, model Hirano bodies can form but are smaller than controls at early times of formation. The ultrastructure of model Hirano bodies did not reveal any major difference in structure and organization in the presence of inhibitors. In summary, these results support the conclusion that formation of model Hirano bodies is promoted by gain-of-function actin filament bundling, which enhances actin filament stabilization. Microtubules and myosin II contribute to but are not required for formation of model Hirano bodies.