The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Victoria A Lawson - One of the best experts on this subject based on the ideXlab platform.
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prpc related signal transduction is influenced by copper membrane integrity and the Alpha Cleavage site
Cell Research, 2009Co-Authors: Cathryn L Haigh, Victoria Lewis, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A LawsonAbstract:PrP C -related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site
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PrP^C-related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site
Cell Research, 2009Co-Authors: Cathryn L Haigh, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A Lawson, Victoria A Lewis, Steven J. CollinsAbstract:The copper-binding, membrane-anchored, cellular prion protein (PrP^C) has two constitutive Cleavage sites producing distinct N- and C-terminal fragments (N1/C1 and N2/C2). Using RK13 cells expressing either human PrP^C, mouse PrP^C or mouse PrP^C carrying the 3F4 epitope, this study explored the influence of the PrP^C primary sequence on endoproteolytic Cleavage and one putative PrP^C function, MAP kinase signal transduction, in response to exogenous copper with or without a perturbed membrane environment. PrP^C primary sequence, especially that around the N1/C1 Cleavage site, appeared to influence basal levels of proteolysis at this location and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, with increased processing demonstrating an inverse relationship with basal ERK1/2 activation. Human PrP^C showed increased N1/C1 Cleavage in response to copper alone, accompanied by specific p38 and JNK/SAPK phosphorylation. Combined exposure to copper plus the cholesterol-sequestering antibiotic filipin resulted in a mouse PrP^C-specific substantial increase in signal protein phosphorylation, accompanied by an increase in N1/C1 Cleavage. Mouse PrP^C harboring the human N1/C1 Cleavage site assumed more human-like profiles basally and in response to copper and altered membrane environments. Our results demonstrate that the PrP^C primary sequence around the N1/C1 Cleavage site influences endoproteolytic processing at this location, which appears linked to MAP kinase signal transduction both basally and in response to copper. Further, the primary sequence appears to confer a mutual dependence of N1/C1 Cleavage and membrane integrity on the fidelity of PrP^C-related signal transduction in response to exogenous stimuli.
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PrPC-related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site.
Cell Research, 2009Co-Authors: Cathryn L Haigh, Victoria Lewis, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A Lawson, Steven J. CollinsAbstract:The copper-binding, membrane-anchored, cellular prion protein (PrP(C)) has two constitutive Cleavage sites producing distinct N- and C-terminal fragments (N1/C1 and N2/C2). Using RK13 cells expressing either human PrP(C), mouse PrP(C) or mouse PrP(C) carrying the 3F4 epitope, this study explored the influence of the PrP(C) primary sequence on endoproteolytic Cleavage and one putative PrP(C) function, MAP kinase signal transduction, in response to exogenous copper with or without a perturbed membrane environment. PrP(C) primary sequence, especially that around the N1/C1 Cleavage site, appeared to influence basal levels of proteolysis at this location and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, with increased processing demonstrating an inverse relationship with basal ERK1/2 activation. Human PrP(C) showed increased N1/C1 Cleavage in response to copper alone, accompanied by specific p38 and JNK/SAPK phosphorylation. Combined exposure to copper plus the cholesterol-sequestering antibiotic filipin resulted in a mouse PrP(C)-specific substantial increase in signal protein phosphorylation, accompanied by an increase in N1/C1 Cleavage. Mouse PrP(C) harboring the human N1/C1 Cleavage site assumed more human-like profiles basally and in response to copper and altered membrane environments. Our results demonstrate that the PrP(C) primary sequence around the N1/C1 Cleavage site influences endoproteolytic processing at this location, which appears linked to MAP kinase signal transduction both basally and in response to copper. Further, the primary sequence appears to confer a mutual dependence of N1/C1 Cleavage and membrane integrity on the fidelity of PrP(C)-related signal transduction in response to exogenous stimuli.
Atanasio Pandiella - One of the best experts on this subject based on the ideXlab platform.
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autocrine regulation of membrane transforming growth factor Alpha Cleavage
Journal of Biological Chemistry, 1996Co-Authors: Jose Baselga, John Mendelsohn, Atanasio PandiellaAbstract:Abstract Transforming growth factor α (TGF-α) is biosynthesized as a membrane-bound precursor protein, pro-TGF-α, that undergoes sequential endoproteolytic Cleavages to release a soluble form of the factor. In the present study, we have analyzed the biosynthesis and regulation of TGF-α production in human tumor-derived cell lines that endogenously express pro-TGF-α and the epidermal growth factor (EGF) receptor. These cells biosynthesized membrane-anchored forms of the TGF-α that accumulated on the cell surface. Membrane-bound pro-TGF-α interacted with the EGF receptor, and complexes of receptor and pro-TGF-α contained tyrosine-phosphorylated receptor. Activation of the EGF receptor by soluble EGF or TGF-α had a dual effect on TGF-α production: an increase in pro-TGF-α mRNA levels and an increase in pro-TGF-α Cleavage. These effects were largely prevented by preincubation with an anti-EGF receptor monoclonal antibody that blocked ligand binding. Growth factor autoinduction of Cleavage could be stimulated by several second messenger pathways that are activated by the EGF receptor, including protein kinase C and intracellular calcium, and by other alternative mechanisms. EGF-stimulated Cleavage of pro-TGF-α could be partially blocked by inhibition of these second messenger pathways. These results suggest that juxtacrine stimulation takes place in human tumor cells that coexpress both the EGF receptor and membrane-anchored TGF-α and that TGF-α is able to induce its own endoproteolytic Cleavage by activating the EGF receptor.
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Activated release of membrane-anchored TGF-Alpha in the absence of cytosol.
Journal of Cell Biology, 1993Co-Authors: Marcus W. Bosenberg, Atanasio Pandiella, Joan MassagueAbstract:The ectodomain of proTGF-Alpha, a membrane-anchored growth factor, is converted into soluble TGF-Alpha by a regulated cellular proteolytic system that recognizes proTGF-Alpha via the C-terminal valine of its cytoplasmic tail. In order to define the biochemical components involved in proTGF-Alpha Cleavage, we have used cells permeabilized with streptolysin O (SLO) that have been extensively washed to remove cytosol. PMA, acting through a Ca(2+)-independent protein kinase C, activates Cleavage as efficiently in permeabilized cells as it does in intact cells. ProTGF-Alpha Cleavage is also stimulated by GTP gamma S through a mechanism whose pharmacological properties suggest the involvement of a heterotrimeric G protein acting upstream of the PMA-sensitive Ca(2+)-independent protein kinase C. Activated proTGF-Alpha Cleavage is dependent on ATP hydrolysis, appears not to require vesicular traffic, and acts specifically on proTGF-Alpha that has reached the cell surface. These results indicate that proTGF-Alpha is cleaved from the cell surface by a regulated system whose signaling, recognition, and proteolytic components are retained in cells devoid of cytosol.
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multiple signals activate Cleavage of the membrane transforming growth factor Alpha precursor
Journal of Biological Chemistry, 1991Co-Authors: Atanasio Pandiella, Joan MassagueAbstract:Abstract Cleavage of the membrane-anchored precursor for transforming growth factor-Alpha (TGF-Alpha), a rate-limiting step in the generation of soluble TGF-Alpha, can be stimulated by phorbol esters acting via protein kinase C. In the present study, activators of other intracellular signaling pathways were tested for their ability to stimulate pro-TGF-Alpha Cleavage in Chinese hamster ovary cells transfected with a pro-TGF-Alpha cDNA. Treatment with the Ca2+ ionophore, A23187, rapidly increased the rate of pro-TGF-Alpha Cleavage over 25-fold. This effect of A23187 on pro-TGF-Alpha Cleavage was dependent on the influx of extracellular calcium and was largely independent of protein kinase C activation. In contrast, phorbol 12-myristate 13-acetate stimulation of pro-TGF-Alpha Cleavage via activation of protein kinase C did not require extracellular calcium. Stimulation of pro-TGF-Alpha Cleavage by serum was largely independent of both protein kinase C and extracellular calcium influx, whereas activators of protein kinase A and protein kinase G did not stimulate pro-TGF-Alpha Cleavage. These results suggest that regulation of pro-TGF-Alpha Cleavage is a complex process that can be controlled by extracellular agents via at least three distinct signal transduction pathways.
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Cleavage of the membrane precursor for transforming growth factor Alpha is a regulated process
Proceedings of the National Academy of Sciences of the United States of America, 1991Co-Authors: Atanasio Pandiella, Joan MassagueAbstract:Transforming growth factor Alpha (TGF-Alpha) is generated by Cleavage of a membrane-anchored precursor protein, proTGF-Alpha. ProTGF-Alpha is cleaved at a slow rate and accumulates on the cell surface, thereby mediating cell-cell adhesion and mitogenic stimulation. We show here that Cleavage of membrane proTGF-Alpha by an elastase-like enzyme constitutes an important regulatory step in the generation of soluble TGF-Alpha. Cleavage is activated in response to serum factors and tumor-promoting phorbol esters, leading to depletion of cell surface proTGF-Alpha, which disperses as soluble factor. Activation of proTGF-Alpha Cleavage is mediated by protein kinase C-dependent and -independent mechanisms. The results demonstrate the existence of mechanisms that control the switch of TGF-Alpha from a juxtacrine to a paracrine growth factor.
Cathryn L Haigh - One of the best experts on this subject based on the ideXlab platform.
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prpc related signal transduction is influenced by copper membrane integrity and the Alpha Cleavage site
Cell Research, 2009Co-Authors: Cathryn L Haigh, Victoria Lewis, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A LawsonAbstract:PrP C -related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site
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PrP^C-related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site
Cell Research, 2009Co-Authors: Cathryn L Haigh, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A Lawson, Victoria A Lewis, Steven J. CollinsAbstract:The copper-binding, membrane-anchored, cellular prion protein (PrP^C) has two constitutive Cleavage sites producing distinct N- and C-terminal fragments (N1/C1 and N2/C2). Using RK13 cells expressing either human PrP^C, mouse PrP^C or mouse PrP^C carrying the 3F4 epitope, this study explored the influence of the PrP^C primary sequence on endoproteolytic Cleavage and one putative PrP^C function, MAP kinase signal transduction, in response to exogenous copper with or without a perturbed membrane environment. PrP^C primary sequence, especially that around the N1/C1 Cleavage site, appeared to influence basal levels of proteolysis at this location and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, with increased processing demonstrating an inverse relationship with basal ERK1/2 activation. Human PrP^C showed increased N1/C1 Cleavage in response to copper alone, accompanied by specific p38 and JNK/SAPK phosphorylation. Combined exposure to copper plus the cholesterol-sequestering antibiotic filipin resulted in a mouse PrP^C-specific substantial increase in signal protein phosphorylation, accompanied by an increase in N1/C1 Cleavage. Mouse PrP^C harboring the human N1/C1 Cleavage site assumed more human-like profiles basally and in response to copper and altered membrane environments. Our results demonstrate that the PrP^C primary sequence around the N1/C1 Cleavage site influences endoproteolytic processing at this location, which appears linked to MAP kinase signal transduction both basally and in response to copper. Further, the primary sequence appears to confer a mutual dependence of N1/C1 Cleavage and membrane integrity on the fidelity of PrP^C-related signal transduction in response to exogenous stimuli.
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PrPC-related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site.
Cell Research, 2009Co-Authors: Cathryn L Haigh, Victoria Lewis, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A Lawson, Steven J. CollinsAbstract:The copper-binding, membrane-anchored, cellular prion protein (PrP(C)) has two constitutive Cleavage sites producing distinct N- and C-terminal fragments (N1/C1 and N2/C2). Using RK13 cells expressing either human PrP(C), mouse PrP(C) or mouse PrP(C) carrying the 3F4 epitope, this study explored the influence of the PrP(C) primary sequence on endoproteolytic Cleavage and one putative PrP(C) function, MAP kinase signal transduction, in response to exogenous copper with or without a perturbed membrane environment. PrP(C) primary sequence, especially that around the N1/C1 Cleavage site, appeared to influence basal levels of proteolysis at this location and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, with increased processing demonstrating an inverse relationship with basal ERK1/2 activation. Human PrP(C) showed increased N1/C1 Cleavage in response to copper alone, accompanied by specific p38 and JNK/SAPK phosphorylation. Combined exposure to copper plus the cholesterol-sequestering antibiotic filipin resulted in a mouse PrP(C)-specific substantial increase in signal protein phosphorylation, accompanied by an increase in N1/C1 Cleavage. Mouse PrP(C) harboring the human N1/C1 Cleavage site assumed more human-like profiles basally and in response to copper and altered membrane environments. Our results demonstrate that the PrP(C) primary sequence around the N1/C1 Cleavage site influences endoproteolytic processing at this location, which appears linked to MAP kinase signal transduction both basally and in response to copper. Further, the primary sequence appears to confer a mutual dependence of N1/C1 Cleavage and membrane integrity on the fidelity of PrP(C)-related signal transduction in response to exogenous stimuli.
Joan Massague - One of the best experts on this subject based on the ideXlab platform.
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Transforming growth factor-Alpha and beta-amyloid precursor protein share a secretory mechanism.
Journal of Cell Biology, 1995Co-Authors: Joaquín Arribas, Joan MassagueAbstract:Cleavage and release of membrane protein ectodomains, a regulated process that affects many cell surface proteins, remains largely uncharacterized. To investigate whether cell surface proteins are cleaved through a shared mechanism or through multiple independent mechanisms, we mutagenized Chinese hamster ovary (CHO) cells and selected clones that were unable to cleave membrane-anchored transforming growth factor Alpha (TGF-Alpha). The defect in TGF-Alpha Cleavage in these clones is most apparent upon cell treatment with the protein kinase C (PKC) activator PMA, which stimulates TGF-Alpha Cleavage in wild-type cells. The mutant clones do not have defects in TFG-Alpha expression, transport to the cell surface or turnover. Concomitant with the loss of TGF-Alpha Cleavage, these clones have lost the ability to cleave many structurally unrelated membrane proteins in response to PMA. These proteins include beta-amyloid precursor protein (beta-APP), whose Cleavage into a secreted form avoids conversion into the amyloidogenic peptide A beta, and a group of cell surface proteins whose release into the medium is stimulated by PMA in wild type CHO cells but not in mutants. The mutations prevent Cleavage by PKC-dependent as well as PKC-independent mechanisms, and thus affect an essential component that functions downstream of these various signaling mechanisms. We propose that regulated Cleavage and secretion of membrane protein ectodomains is mediated by a common system whose components respond to multiple activators and act on susceptible proteins of diverse structure and function.
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Activated release of membrane-anchored TGF-Alpha in the absence of cytosol.
Journal of Cell Biology, 1993Co-Authors: Marcus W. Bosenberg, Atanasio Pandiella, Joan MassagueAbstract:The ectodomain of proTGF-Alpha, a membrane-anchored growth factor, is converted into soluble TGF-Alpha by a regulated cellular proteolytic system that recognizes proTGF-Alpha via the C-terminal valine of its cytoplasmic tail. In order to define the biochemical components involved in proTGF-Alpha Cleavage, we have used cells permeabilized with streptolysin O (SLO) that have been extensively washed to remove cytosol. PMA, acting through a Ca(2+)-independent protein kinase C, activates Cleavage as efficiently in permeabilized cells as it does in intact cells. ProTGF-Alpha Cleavage is also stimulated by GTP gamma S through a mechanism whose pharmacological properties suggest the involvement of a heterotrimeric G protein acting upstream of the PMA-sensitive Ca(2+)-independent protein kinase C. Activated proTGF-Alpha Cleavage is dependent on ATP hydrolysis, appears not to require vesicular traffic, and acts specifically on proTGF-Alpha that has reached the cell surface. These results indicate that proTGF-Alpha is cleaved from the cell surface by a regulated system whose signaling, recognition, and proteolytic components are retained in cells devoid of cytosol.
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multiple signals activate Cleavage of the membrane transforming growth factor Alpha precursor
Journal of Biological Chemistry, 1991Co-Authors: Atanasio Pandiella, Joan MassagueAbstract:Abstract Cleavage of the membrane-anchored precursor for transforming growth factor-Alpha (TGF-Alpha), a rate-limiting step in the generation of soluble TGF-Alpha, can be stimulated by phorbol esters acting via protein kinase C. In the present study, activators of other intracellular signaling pathways were tested for their ability to stimulate pro-TGF-Alpha Cleavage in Chinese hamster ovary cells transfected with a pro-TGF-Alpha cDNA. Treatment with the Ca2+ ionophore, A23187, rapidly increased the rate of pro-TGF-Alpha Cleavage over 25-fold. This effect of A23187 on pro-TGF-Alpha Cleavage was dependent on the influx of extracellular calcium and was largely independent of protein kinase C activation. In contrast, phorbol 12-myristate 13-acetate stimulation of pro-TGF-Alpha Cleavage via activation of protein kinase C did not require extracellular calcium. Stimulation of pro-TGF-Alpha Cleavage by serum was largely independent of both protein kinase C and extracellular calcium influx, whereas activators of protein kinase A and protein kinase G did not stimulate pro-TGF-Alpha Cleavage. These results suggest that regulation of pro-TGF-Alpha Cleavage is a complex process that can be controlled by extracellular agents via at least three distinct signal transduction pathways.
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Cleavage of the membrane precursor for transforming growth factor Alpha is a regulated process
Proceedings of the National Academy of Sciences of the United States of America, 1991Co-Authors: Atanasio Pandiella, Joan MassagueAbstract:Transforming growth factor Alpha (TGF-Alpha) is generated by Cleavage of a membrane-anchored precursor protein, proTGF-Alpha. ProTGF-Alpha is cleaved at a slow rate and accumulates on the cell surface, thereby mediating cell-cell adhesion and mitogenic stimulation. We show here that Cleavage of membrane proTGF-Alpha by an elastase-like enzyme constitutes an important regulatory step in the generation of soluble TGF-Alpha. Cleavage is activated in response to serum factors and tumor-promoting phorbol esters, leading to depletion of cell surface proTGF-Alpha, which disperses as soluble factor. Activation of proTGF-Alpha Cleavage is mediated by protein kinase C-dependent and -independent mechanisms. The results demonstrate the existence of mechanisms that control the switch of TGF-Alpha from a juxtacrine to a paracrine growth factor.
Colin L Masters - One of the best experts on this subject based on the ideXlab platform.
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prpc related signal transduction is influenced by copper membrane integrity and the Alpha Cleavage site
Cell Research, 2009Co-Authors: Cathryn L Haigh, Victoria Lewis, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A LawsonAbstract:PrP C -related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site
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PrP^C-related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site
Cell Research, 2009Co-Authors: Cathryn L Haigh, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A Lawson, Victoria A Lewis, Steven J. CollinsAbstract:The copper-binding, membrane-anchored, cellular prion protein (PrP^C) has two constitutive Cleavage sites producing distinct N- and C-terminal fragments (N1/C1 and N2/C2). Using RK13 cells expressing either human PrP^C, mouse PrP^C or mouse PrP^C carrying the 3F4 epitope, this study explored the influence of the PrP^C primary sequence on endoproteolytic Cleavage and one putative PrP^C function, MAP kinase signal transduction, in response to exogenous copper with or without a perturbed membrane environment. PrP^C primary sequence, especially that around the N1/C1 Cleavage site, appeared to influence basal levels of proteolysis at this location and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, with increased processing demonstrating an inverse relationship with basal ERK1/2 activation. Human PrP^C showed increased N1/C1 Cleavage in response to copper alone, accompanied by specific p38 and JNK/SAPK phosphorylation. Combined exposure to copper plus the cholesterol-sequestering antibiotic filipin resulted in a mouse PrP^C-specific substantial increase in signal protein phosphorylation, accompanied by an increase in N1/C1 Cleavage. Mouse PrP^C harboring the human N1/C1 Cleavage site assumed more human-like profiles basally and in response to copper and altered membrane environments. Our results demonstrate that the PrP^C primary sequence around the N1/C1 Cleavage site influences endoproteolytic processing at this location, which appears linked to MAP kinase signal transduction both basally and in response to copper. Further, the primary sequence appears to confer a mutual dependence of N1/C1 Cleavage and membrane integrity on the fidelity of PrP^C-related signal transduction in response to exogenous stimuli.
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PrPC-related signal transduction is influenced by copper, membrane integrity and the Alpha Cleavage site.
Cell Research, 2009Co-Authors: Cathryn L Haigh, Victoria Lewis, Laura J Vella, Colin L Masters, Andrew F Hill, Victoria A Lawson, Steven J. CollinsAbstract:The copper-binding, membrane-anchored, cellular prion protein (PrP(C)) has two constitutive Cleavage sites producing distinct N- and C-terminal fragments (N1/C1 and N2/C2). Using RK13 cells expressing either human PrP(C), mouse PrP(C) or mouse PrP(C) carrying the 3F4 epitope, this study explored the influence of the PrP(C) primary sequence on endoproteolytic Cleavage and one putative PrP(C) function, MAP kinase signal transduction, in response to exogenous copper with or without a perturbed membrane environment. PrP(C) primary sequence, especially that around the N1/C1 Cleavage site, appeared to influence basal levels of proteolysis at this location and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, with increased processing demonstrating an inverse relationship with basal ERK1/2 activation. Human PrP(C) showed increased N1/C1 Cleavage in response to copper alone, accompanied by specific p38 and JNK/SAPK phosphorylation. Combined exposure to copper plus the cholesterol-sequestering antibiotic filipin resulted in a mouse PrP(C)-specific substantial increase in signal protein phosphorylation, accompanied by an increase in N1/C1 Cleavage. Mouse PrP(C) harboring the human N1/C1 Cleavage site assumed more human-like profiles basally and in response to copper and altered membrane environments. Our results demonstrate that the PrP(C) primary sequence around the N1/C1 Cleavage site influences endoproteolytic processing at this location, which appears linked to MAP kinase signal transduction both basally and in response to copper. Further, the primary sequence appears to confer a mutual dependence of N1/C1 Cleavage and membrane integrity on the fidelity of PrP(C)-related signal transduction in response to exogenous stimuli.
