The Experts below are selected from a list of 36627 Experts worldwide ranked by ideXlab platform
George E. Davis - One of the best experts on this subject based on the ideXlab platform.
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an integrin and rho gtpase dependent pinocytic Vacuole mechanism controls capillary lumen formation in collagen and fibrin matrices
Microcirculation, 2003Co-Authors: George E. Davis, Kayla J BaylessAbstract:A major question that remains unanswered concerning endothelial cell (EC) morphogenesis is how lumens are formed in three-dimensional extracellular matrices (ECMs). Studies from many laboratories have revealed a critical role for an ECM-integrin-cytoskeletal signaling axis during EC morphogenesis. We have discovered a mechanism involving intracellular Vacuole formation and coalescence that is required for lumen formation in several in vitro models of morphogenesis. In addition, a series of studies have observed Vacuoles in vivo during angiogenic events. These Vacuoles form through an integrin-dependent pinocytic mechanism in either collagen or fibrin matrices. In addition, we have shown that the Cdc42 and Rac1 guanosine triphosphatases (GTPases), which control actin and microtubule cytoskeletal networks, are required for Vacuole and lumen formation. These GTPases are also known to regulate integrin signaling and are activated after integrin-matrix interactions. Furthermore, the expression of green fluorescent protein-Rac1 or -Cdc42 chimeric proteins in ECs results in the targeting of these fusion proteins to intracellular Vacuole membranes during lumen formation. Thus, a matrix-integrin-cytoskeletal signaling axis involving both the Cdc42 and Rac1 GTPases regulates the process of EC lumen formation in three-dimensional collagen or fibrin matrices.
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an α2β1 integrin dependent pinocytic mechanism involving intracellular Vacuole formation and coalescence regulates capillary lumen and tube formation in three dimensional collagen matrix
Experimental Cell Research, 1996Co-Authors: George E. Davis, Charles W CamarilloAbstract:Abstract Human endothelial cells, when suspended within three-dimensional collagen matrices, develop intracellular Vacuoles that coalesce to form capillary lumens and tubes. Vacuole and lumen formation are completely dependent on the collagen-binding integrin α2β1, while other endothelial cell integrins had no apparent influence. Vacuole formation occurs by a pinocytic process with internalization of plasma membrane and molecules from the extracellular space, such as fluorescent tracers. By immunofluorescence, Vacuole membranes were found to contain associated cell surface proteins, proteins involved in endosomal trafficking (i.e., caveolin and annexin II), and F-actin. Furthermore, some Vacuole compartments contained von Willebrand factor. Integrin-regulated Vacuole formation and coalescence are major mechanisms controlling capillary lumen and tube formation within a three-dimensional extracellular matrix.
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an alpha 2 beta 1 integrin dependent pinocytic mechanism involving intracellular Vacuole formation and coalescence regulates capillary lumen and tube formation in three dimensional collagen matrix
Experimental Cell Research, 1996Co-Authors: George E. Davis, Charles W CamarilloAbstract:Human endothelial cells, when suspended within three-dimensional collagen matrices, develop intracellular Vacuoles that coalesce to form capillary lumens and tubes. Vacuole and lumen formation are completely dependent on the collagen-binding integrin alpha 2 beta 1, while other endothelial cell integrins had no apparent influence. Vacuole formation occurs by a pinocytic process with internalization of plasma membrane and molecules from the extracellular space, such as fluorescent tracers. By immunofluorescence, Vacuole membranes were found to contain associated cell surface proteins, proteins involved in endosomal trafficking (i.e., caveolin and annexin II), and F-actin. Furthermore, some Vacuole compartments contained von Willebrand factor. Integrin-regulated Vacuole formation and coalescence are major mechanisms controlling capillary lumen and tube formation within a three-dimensional extracellular matrix.
Charles W Camarillo - One of the best experts on this subject based on the ideXlab platform.
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an α2β1 integrin dependent pinocytic mechanism involving intracellular Vacuole formation and coalescence regulates capillary lumen and tube formation in three dimensional collagen matrix
Experimental Cell Research, 1996Co-Authors: George E. Davis, Charles W CamarilloAbstract:Abstract Human endothelial cells, when suspended within three-dimensional collagen matrices, develop intracellular Vacuoles that coalesce to form capillary lumens and tubes. Vacuole and lumen formation are completely dependent on the collagen-binding integrin α2β1, while other endothelial cell integrins had no apparent influence. Vacuole formation occurs by a pinocytic process with internalization of plasma membrane and molecules from the extracellular space, such as fluorescent tracers. By immunofluorescence, Vacuole membranes were found to contain associated cell surface proteins, proteins involved in endosomal trafficking (i.e., caveolin and annexin II), and F-actin. Furthermore, some Vacuole compartments contained von Willebrand factor. Integrin-regulated Vacuole formation and coalescence are major mechanisms controlling capillary lumen and tube formation within a three-dimensional extracellular matrix.
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an alpha 2 beta 1 integrin dependent pinocytic mechanism involving intracellular Vacuole formation and coalescence regulates capillary lumen and tube formation in three dimensional collagen matrix
Experimental Cell Research, 1996Co-Authors: George E. Davis, Charles W CamarilloAbstract:Human endothelial cells, when suspended within three-dimensional collagen matrices, develop intracellular Vacuoles that coalesce to form capillary lumens and tubes. Vacuole and lumen formation are completely dependent on the collagen-binding integrin alpha 2 beta 1, while other endothelial cell integrins had no apparent influence. Vacuole formation occurs by a pinocytic process with internalization of plasma membrane and molecules from the extracellular space, such as fluorescent tracers. By immunofluorescence, Vacuole membranes were found to contain associated cell surface proteins, proteins involved in endosomal trafficking (i.e., caveolin and annexin II), and F-actin. Furthermore, some Vacuole compartments contained von Willebrand factor. Integrin-regulated Vacuole formation and coalescence are major mechanisms controlling capillary lumen and tube formation within a three-dimensional extracellular matrix.
Ikuya Nonaka - One of the best experts on this subject based on the ideXlab platform.
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apoptotic muscle fiber degeneration in distal myopathy with rimmed Vacuoles
Acta Neuropathologica, 2001Co-Authors: Koji Ikezoe, Ikuya NonakaAbstract:Rimmed Vacuole formation, tubulofilamentous nuclear inclusions and muscle fiber atrophy are the characteristic pathological findings in distal myopathy with rimmed Vacuoles (DMRV). Necrotic muscle fibers were few in number and did not appear to account for the muscle weakness, but the nuclear changes with myofibrillar degeneration followed by rimmed Vacuole formation appeared to be the major reason for the muscle fiber atrophy in DMRV. To determine whether the nuclear change in DMRV was related to apoptosis, we examined 15 muscle biopsy specimens immunohistochemically, and 7 of them ultrastructurally. The characteristic tubulofilamentous nuclear inclusions were found in 4 and the typical fragmented apoptotic nuclei in 3 of the 7 muscle biopsy samples examined by electron microscopy. TUNEL-positive nuclei reflecting apoptotic DNA fragmentation were found in 13 of 15 biopsies ranging from a few to approximately 1.5% of myonuclei. Apoptosis-specific protein was expressed in the sarcoplasm of atrophic fibers in 13 biopsies both with or without rimmed Vacuoles. These findings suggest that the apoptotic process plays a crucial role in myofibrillar degeneration followed by autophagocytosis, i.e., rimmed Vacuole formation, in DMRV.
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distal myopathy with rimmed Vacuoles
Neuromuscular Disorders, 1998Co-Authors: Ikuya Nonaka, Nobuyuki Murakami, Y. Suzuki, Mitsuru KawaiAbstract:Abstract Distal myopathy with rimmed Vacuoles is an autosomal recessively inherited disorder with preferential involvement of the anterior tibial muscle. Recently the gene was discovered to be mapped to chromosome 9, the same region as in familial inclusion body myopathy (rimmed Vacuole myopathy sparing the quadriceps). The onset of the disease was in young adults 20–40 years of age, averaging 26 years. The disease was progressive and most of the patients became non-ambulant within 12 years after the onset. The striking and common pathologic finding was the presence of rimmed Vacuoles in muscle fibers with little evidence of necrotic or regenerative processes. Nuclear change with tubulofilamentous inclusions probably induces focal myofibrillar degeneration which activates the lysosomal system, resulting in active autophagocytosis and myelin body formation, i.e. rimmed Vacuole formation.
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muscle fiber degeneration in distal myopathy with rimmed Vacuole formation
Acta Neuropathologica, 1995Co-Authors: Nobuyuki Murakami, Yasuo Ihara, Ikuya NonakaAbstract:In 11 patients with distal myopathy with rimmed Vacuole formation (DMRV), a well-known autosomal recessively inherited disorder, the rimmed Vacuole formation appears to be the main pathological change accounting for the progressive muscle fiber degeneration. To gain a better understanding of the pathophysiology of the Vacuole formation, we applied Congo red and immunohistochemical stains to muscle biopsies from these patients and the results were compared with those of patients with inclusion body myositis (IBM). The Vacuoles in DMRV contained Congophilic amyloid material and deposits immunoreactive for β-amyloid protein, both the NH2 and COOH termini of β-amyloid protein precursor, ubiquitin, and tau protein. These results were similar to those seen in our present cases of IBM as well as in previously reported cases. Therefore, there may be no pathogenetic differences in the formation of rimmed Vacuoles in DMRV and IBM. Nevertheless, the degenerative process involved in rimmed Vacuole formation in various diseases may share a common pathogenetic mechanism with that in amyloid-plaque formation in Alzheimer's disease brain as has been proposed previously.
Russell L Jones - One of the best experts on this subject based on the ideXlab platform.
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from storage compartment to lytic organelle the metamorphosis of the aleurone protein storage Vacuole
Annals of Botany, 1998Co-Authors: Paul C Bethke, Sarah J Swanson, Stefan Hillmer, Russell L JonesAbstract:Abstract Protein storage Vacuoles are found in a variety of tissues but are especially abundant in the storage organs of fruits and seeds. In this review, we focus on the protein storage Vacuoles of cereal aleurone. In the mature grain, these organelles are repositories for reserve nitrogen, carbon and minerals. Following imbibition, protein storage Vacuoles of cereal aleurone change from storage compartments to lytic organelles. Changes in protein storage Vacuole structure and enzymatic activity during this transition are discussed. It is emphasized that protein storage Vacuoles are poised for reserve mobilization, and that gibberellin perception by the aleurone cell initiates a signalling cascade that promotes acidification of the Vacuole lumen and activation of enzymes and transporters.
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barley aleurone cells contain two types of Vacuoles characterization of lytic organelles by use of fluorescent probes
The Plant Cell, 1998Co-Authors: Sarah J Swanson, Paul C Bethke, Russell L JonesAbstract:Light microscopy was used to study the structure and function of Vacuoles in living protoplasts of barley ( Hordeum vulgare cv Himalaya) aleurone. Light microscopy showed that aleurone protoplasts contain two distinct types of Vacuole: the protein storage Vacuole and a lysosome-like organelle, which we have called the secondary Vacuole. Fluorescence microscopy using pH-sensitive fluorescent probes and a fluorogenic substrate for cysteine proteases showed that both protein storage Vacuoles and secondary Vacuoles are acidic, lytic organelles. Ratio imaging showed that the pH of secondary Vacuoles was lower in aleurone protoplasts incubated in gibberellic acid than in those incubated in abscisic acid. Uptake of fluorescent probes into intact, isolated protein storage Vacuoles and secondary Vacuoles required ATP and occurred via at least two types of vanadate-sensitive, ATP-dependent tonoplast transporters. One transporter catalyzed the accumulation of glutathione-conjugated probes, and another transported probes not conjugated to glutathione.
John C Rogers - One of the best experts on this subject based on the ideXlab platform.
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tonoplast intrinsic protein isoforms as markers for vacuolar functions
The Plant Cell, 1999Co-Authors: Guangyuh Jauh, Thomas E Phillips, John C RogersAbstract:Plant cell Vacuoles may have storage or lytic functions, but biochemical markers specific for the tonoplasts of functionally distinct Vacuoles are poorly defined. Here, we use antipeptide antibodies specific for the tonoplast intrinsic proteins alpha-TIP, gamma-TIP, and delta-TIP in confocal immunofluorescence experiments to test the hypothesis that different TIP isoforms may define different Vacuole functions. Organelles labeled with these antibodies were also labeled with antipyrophosphatase antibodies, demonstrating that regardless of their size, they had the expected characteristics of Vacuoles. Our results demonstrate that the storage Vacuole tonoplast contains delta-TIP, protein storage Vacuoles containing seed-type storage proteins are marked by alpha- and delta- or alpha- and delta- plus gamma-TIP, whereas Vacuoles storing vegetative storage proteins and pigments are marked by delta-TIP alone or delta- plus gamma-TIP. In contrast, those marked by gamma-TIP alone have characteristics of lytic Vacuoles, and results from other researchers indicate that alpha-TIP alone is a marker for autophagic Vacuoles. In root tips, relatively undifferentiated cells that contain Vacuoles labeled separately for each of the three TIPs have been identified. These results argue that plant cells have the ability to generate and maintain three separate Vacuole organelles, with each being marked by a different TIP, and that the functional diversity of the vacuolar system may be generated from different combinations of the three basic types.
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δ tonoplast intrinsic protein defines unique plant Vacuole functions
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Guangyuh Jauh, Andreas M Fischer, Howard D Grimes, Clarence A Ryan, John C RogersAbstract:Plant cell Vacuoles may have either storage or degradative functions. Vegetative storage proteins (VSPs) are synthesized in response to wounding and to developmental switches that affect carbon and nitrogen sinks. Here we show that VSPs are stored in a unique type of Vacuole that is derived from degradative central Vacuoles coincident with insertion of a new tonoplast intrinsic protein (TIP), δ-TIP, into their membranes. This finding demonstrates a tight coupling between the presence of δ-TIP and acquisition of a specialized storage function and indicates that TIP isoforms may determine Vacuole identity.
