The Experts below are selected from a list of 1032 Experts worldwide ranked by ideXlab platform
Miriam Cnop - One of the best experts on this subject based on the ideXlab platform.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Abstract Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
Junying Yuan - One of the best experts on this subject based on the ideXlab platform.
-
icp34 5 dependent and independent activities of Salubrinal in herpes simplex virus 1 infected cells
Virology, 2008Co-Authors: Kevin F Bryant, Michael Boyce, Junying Yuan, Elizabeth R Macari, Natasha Malik, Donald M CoenAbstract:The small molecule Salubrinal has antiviral activity against herpes simplex virus-1 (HSV-1) and inhibits dephosphorylation of eIF2α mediated by the HSV-1 protein ICP34.5. We investigated whether Salubrinal's activities in infected cells depend on ICP34.5. An ICP34.5 deletion mutant was as sensitive as wild type HSV-1 to Salubrinal inhibition of plaque formation in Vero cells. However, Salubrinal induced formation of syncytia in infected Vero cells, which was enhanced by ICP34.5 mutations. Expression of HSV-1 US11 with immediate early kinetics, which is known to suppress the effects of ICP34.5 mutations, resulted in slight resistance to Salubrinal in murine embryonic fibroblasts, and substantial resistance in those cells when ICP34.5 was additionally mutated. ICP34.5 mutations, but not immediate early expression of US11, prevented Salubrinal's ability to increase phosphorylation of eIF2α during HSV-1 infection of Vero cells. Taken together, our data indicate that Salubrinal has both ICP34.5-dependent and -independent activities in HSV-1 infected cells.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Abstract Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
Michael Boyce - One of the best experts on this subject based on the ideXlab platform.
-
icp34 5 dependent and independent activities of Salubrinal in herpes simplex virus 1 infected cells
Virology, 2008Co-Authors: Kevin F Bryant, Michael Boyce, Junying Yuan, Elizabeth R Macari, Natasha Malik, Donald M CoenAbstract:The small molecule Salubrinal has antiviral activity against herpes simplex virus-1 (HSV-1) and inhibits dephosphorylation of eIF2α mediated by the HSV-1 protein ICP34.5. We investigated whether Salubrinal's activities in infected cells depend on ICP34.5. An ICP34.5 deletion mutant was as sensitive as wild type HSV-1 to Salubrinal inhibition of plaque formation in Vero cells. However, Salubrinal induced formation of syncytia in infected Vero cells, which was enhanced by ICP34.5 mutations. Expression of HSV-1 US11 with immediate early kinetics, which is known to suppress the effects of ICP34.5 mutations, resulted in slight resistance to Salubrinal in murine embryonic fibroblasts, and substantial resistance in those cells when ICP34.5 was additionally mutated. ICP34.5 mutations, but not immediate early expression of US11, prevented Salubrinal's ability to increase phosphorylation of eIF2α during HSV-1 infection of Vero cells. Taken together, our data indicate that Salubrinal has both ICP34.5-dependent and -independent activities in HSV-1 infected cells.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Abstract Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
Hiroki Yokota - One of the best experts on this subject based on the ideXlab platform.
-
Host protein tyrosine phosphatase 1B is important for Salubrinal-induced fusion.
2018Co-Authors: Jillian C. Carmichael, Hiroki Yokota, Rebecca C. Craven, Anthony Schmitt, John W. WillsAbstract:(A) Vero cells were infected with strain 17 (MOI = 3) and incubated in DMSO, 50 μM Salubrinal, or 50 μM guanabenz (GBZ) for 12 hours. Cell lysates were prepared in the presence of phosphatase inhibitors and probed via western blotting for total eIF2α and for phosphorylated eIF2α. (B) Cells were infected with KOS (MOI = 3) and incubated in DMSO, Salubrinal, or guanabenz. At 24 hpi, cell lysates and media were harvested, and viral titers (cell lysates + media) were measured. Data are the averages of 2 replicates with statistical significance determined by a student T-test. (C) Cells were infected with strain 17 (MOI = 3) and treated with 50 μM Salubrinal and increasing amounts of PTP1B inhibitors TCS-401 or XXII. At 12 hpi, the fusion ratio was determined by flow cytometry. Data are represented as the mean ±SD from 3 independent experiments, and a student T-test was used to determine statistical significance for samples compared to the Salubrinal-only control. (D) C10 cells were transfected with plasmids encoding gB, gD, gH, and gL in a 3:1:1:1 ratio and treated with DMSO, 50 μM Salubrinal, or 50 μM inhibitor XXII for 16 hours. The 10 largest syncytia per sample were measured by counting the number of nuclei per syncytium. A student T-test was used to compare samples to the DMSO-only control.
-
Differential effects of Salubrinal and inhibitor XXII on HSV-1 syncytial variants.
2018Co-Authors: Jillian C. Carmichael, Hiroki Yokota, Rebecca C. Craven, Anthony Schmitt, John W. WillsAbstract:(A and B) Vero cells were infected with mutant gB.A855V at MOIs of (A) 1 or (B) 0.1. Since this mutant prefers to drive fusion with neighboring uninfected cells, the baseline level is higher at the lower MOI. Cells were treated with increasing amounts of (A) Salubrinal or (B) inhibitor XXII, and at 12 hpi (A) or 24 hpi (B) the fusion ratios were determined by flow cytometry. The data are represented as the mean ±SD from 3 independent experiments, and a student T-test was used to determine statistical significance for samples compared to the DMSO control. (C and D) Cells were infected (MOI = 1) with mutants gK.L118Q or gK.A40V and treated with (C) Salubrinal or (D) inhibitor XXII. At 12 hpi, syncytia were analyzed as in (5A). (E and F) Cells were infected (MOI = 1) with mutant UL20.F222A and treated with (E) Salubrinal or (F) inhibitor XXII. At 12hpi, syncytia were analyzed as in (5A).
-
HSV-1 cell-to-cell spread is limited in PTP1B-/- MEFs.
2018Co-Authors: Jillian C. Carmichael, Hiroki Yokota, Rebecca C. Craven, Anthony Schmitt, John W. WillsAbstract:(A) Virus replication assays were performed in PTP1B+ and PTP1B-/- MEFs infected with strain 17 (MOI = 5). At 6-hour time points, duplicate samples were collected for measurements of the virus titers (cell lysate + medium), which were averaged and plotted. (B) To measure syncytia formation, PTP1B+ MEFs or PTP1B-/- MEFs were infected (MOI = 3) with strain 17 and treated with DMSO, 50 μM Salubrinal, or 50 μM Salubrinal + 30 μM inhibitor XXII. At 24 hpi, cells were immunostained for ZO-1 and DAPI-stained nuclei in syncytia were manually counted. 1000 nuclei were scored per image, and 2 replicates were averaged. (C) To assay for cell-to-cell spread, PTP1B+ MEFs or PTP1B-/- MEFs were infected (100 PFU/well) with strains KOS or 17, and the cells were incubated in medium containing 5 mg/ml pooled IgG. At 42 hpi, the cells were immunostained for VP5, and the areas of 10–15 plaques per sample were measured. Data are represented as mean ±SD from 3 independent experiments. A student T-test was used to determine statistical significance for the PTP1B-/- samples compared to the PTP1B+ control. (D and E) PTP1B+ MEFs or PTP1B-/- MEFs were infected with strain 17 (100 PFU/well) and incubated in medium containing 5 mg/ml of pooled human IgG along with either DMSO or 30 μM inhibitor XXII. At 42 hpi, cells were immunostained for VP5. (D) Representative plaques are shown. (E) To quantify the results, 10–15 plaques per sample were measured, and the mean plaque area was plotted from 2 independent experiments. A student T-test was used to determine statistical significance for samples compared to the PTP1B+ DMSO control. (F) To ascertain their ability to respond to Salubrinal, uninfected PTP1B+ MEFs or PTP1B-/- MEFs were incubated in medium containing DMSO, 50 μM Salubrinal, or 1 μM thapsigargin for 2 hours. Cell lysates were harvested in the presence of phosphatase inhibitors and probed via western blotting for total eIF2α and phosphorylated eIF2α. Duplicate samples were analyzed in the same western blot and band intensities were quantified.
-
Salubrinal-induced fusion of HSV-infected cells is dependent on accessory proteins.
2018Co-Authors: Jillian C. Carmichael, Hiroki Yokota, Rebecca C. Craven, Anthony Schmitt, John W. WillsAbstract:(A) Diagram of relevant HSV-1 proteins involved in cell-to-cell spread and syncytia formation. The core fusion proteins are blue (gB, gH/gL, and gD), and proteins that can be altered to create syncytial variants are purple (gK, UL20, UL24, and gB). Two of the accessory glycoproteins are green (gE and gI), and three of the accessory tegument proteins are yellow (UL11, UL16, and UL21). (B) Vero cells were infected (MOI = 1) with HSV-1 strains KOS or 17 and incubated in medium containing DMSO or 50 μM Salubrinal. At 12 hpi, the cells were immunostained for ZO-1 (red), and nuclei were stained with DAPI. Examples of syncytia are indicated (arrows). (C) Cells were infected with the KOS strain (MOI = 0.5) and incubated in the presence of Salubrinal, as indicated. At 18 hpi, the cells were immunostained for ZO-1, and DAPI-stained nuclei were scored as being inside syncytia or within single cells. 1000 nuclei were scored per image for 3 replicates. Data are represented as mean ±SD, and statistical significance was determined by a student T-test. (D) Cells were infected (MOI = 0.5) with WT, gEΔCT, or ΔUL16 viruses and incubated in the presence of 50 μM Salubrinal for 18 hours. DAPI-stained nuclei were scored as in (1C).
-
The HSV-1 mechanisms of cell-to-cell spread and fusion are critically dependent on host PTP1B
2018Co-Authors: Jillian C. Carmichael, Hiroki Yokota, Rebecca C. Craven, Anthony Schmitt, John W. WillsAbstract:All herpesviruses have mechanisms for passing through cell junctions, which exclude neutralizing antibodies and offer a clear path to neighboring, uninfected cells. In the case of herpes simplex virus type 1 (HSV-1), direct cell-to-cell transmission takes place between epithelial cells and sensory neurons, where latency is established. The spreading mechanism is poorly understood, but mutations in four different HSV-1 genes can dysregulate it, causing neighboring cells to fuse to produce syncytia. Because the host proteins involved are largely unknown (other than the virus entry receptor), we were intrigued by an earlier discovery that cells infected with wild-type HSV-1 will form syncytia when treated with Salubrinal. A biotinylated derivative of this drug was used to pull down cellular complexes, which were analyzed by mass spectrometry. One candidate was a protein tyrosine phosphatase (PTP1B), and although it ultimately proved not to be the target of Salubrinal, it was found to be critical for the mechanism of cell-to-cell spread. In particular, a highly specific inhibitor of PTP1B (CAS 765317-72-4) blocked Salubrinal-induced fusion, and by itself resulted in a dramatic reduction in the ability of HSV-1 to spread in the presence of neutralizing antibodies. The importance of this phosphatase was confirmed in the absence of drugs by using PTP1B-/- cells. Importantly, replication assays showed that virus titers were unaffected when PTP1B was inhibited or absent. Only cell-to-cell spread was altered. We also examined the effects of Salubrinal and the PTP1B inhibitor on the four Syn mutants of HSV-1, and strikingly different responses were found. That is, both drugs individually enhanced fusion for some mutants and reduced fusion for others. PTP1B is the first host factor identified to be specifically required for cell-to-cell spread, and it may be a therapeutic target for preventing HSV-1 reactivation disease.
Laurence Ladriere - One of the best experts on this subject based on the ideXlab platform.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic beta-cell apoptosis and may contribute to beta-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2alpha phosphorylation trigger beta-cell failure and diabetes. Salubrinal selectively inhibits eIF2alpha dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a beta-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary beta-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2alpha phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2alpha branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2alpha phosphorylation is poorly tolerated by beta-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2alpha phosphorylation in beta-cells and must be taken into consideration when designing therapies to protect beta-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2 alpha dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic beta cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Miriam Cnop, Michael Boyce, Junying Yuan, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Decio L EizirikAbstract:Abstract Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
-
selective inhibition of eukaryotic translation initiation factor 2α dephosphorylation potentiates fatty acid induced endoplasmic reticulum stress and causes pancreatic β cell dysfunction and apoptosis
Journal of Biological Chemistry, 2006Co-Authors: Michael Boyce, Miriam Cnop, Laurence Ladriere, Paul Hekerman, Fernanda Ortis, Alessandra K Cardozo, Zeynep Dogusan, Daisy Flamez, Junying YuanAbstract:Free fatty acids cause pancreatic β-cell apoptosis and may contribute to β-cell loss in type 2 diabetes via the induction of endoplasmic reticulum stress. Reductions in eukaryotic translation initiation factor (eIF) 2α phosphorylation trigger β-cell failure and diabetes. Salubrinal selectively inhibits eIF2α dephosphorylation, protects other cells against endoplasmic reticulum stress-mediated apoptosis, and has been proposed as a β-cell protector. Unexpectedly, Salubrinal induced apoptosis in primary β-cells, and it potentiated the deleterious effects of oleate and palmitate. Salubrinal induced a marked eIF2α phosphorylation and potentiated the inhibitory effects of free fatty acids on protein synthesis and insulin release. The synergistic activation of the PERK-eIF2α branch of the endoplasmic reticulum stress response, but not of the IRE1 and activating transcription factor-6 pathways, led to a marked induction of activating transcription factor-4 and the pro-apoptotic transcription factor CHOP. Our findings demonstrate that excessive eIF2α phosphorylation is poorly tolerated by β-cells and exacerbates free fatty acid-induced apoptosis. This modifies the present paradigm regarding the beneficial role of eIF2α phosphorylation in β-cells and must be taken into consideration when designing therapies to protect β-cells in type 2 diabetes.
