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fret based ca2 biosensor camelon d1er  (Addgene inc)


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    Addgene inc fret based ca2 biosensor camelon d1er
    FIGURE 1 Expression of the ER- resident GPx8 attenuates palmitate (PA)- mediated perturbation of intraorganellar <t>Ca2+</t> dynamics. (A) Average trace of time-dependent changes in cytosolic free Ca2+ in control and GPx8 expressing INS-1E cells perifused under basal conditions (KR + 3 mmol/L glucose + 1% FFA-free BSA), followed by 0.5 mmol/L PA-containing KR solution for 5 min. Bars on the right represent the average peak amplitude of cytosolic free Ca2+ in the presence of PA. (B) Average curve of ER luminal and (C) mitochondrial Ca2+ dynamics in control and GPx8 cells transfected with the site-specific <t>FRET-based</t> Ca2+ sensors <t>D1ER</t> or 4mtD3cpv before and after perifusion with 0.5 mmol/L PA. The respective bars show the average depletion of ER luminal Ca2+ and the average peak amplitude of mitochondrial Ca2+ levels in the presence of PA, respectively. Data are means ± SEM of 7–10 independent experiments; *p < .05, **p < .01, ***p < .001 compared with INS-1E control cells (Student's t-test, unpaired, two-tailed).
    Fret Based Ca2 Biosensor Camelon D1er, supplied by Addgene inc, used in various techniques. Bioz Stars score: 93/100, based on 43 PubMed citations. ZERO BIAS - scores, article reviews, protocol conditions and more
    https://www.bioz.com/product/fret+based+ca2+biosensor+camelon+d1er/pcDNA-D1ER+(Plasmid+%2336325)/10__1096_slash_fj__202201237r-59-13-29
    Average 93 stars, based on 43 article reviews
    fret based ca2 biosensor camelon d1er - by Bioz Stars, 2026-09
    93/100 stars

    Images

    1) Product Images from "Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells"

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    Journal: The FASEB Journal

    doi: 10.1096/fj.202201237r

    FIGURE 1 Expression of the ER- resident GPx8 attenuates palmitate (PA)- mediated perturbation of intraorganellar Ca2+ dynamics. (A) Average trace of time-dependent changes in cytosolic free Ca2+ in control and GPx8 expressing INS-1E cells perifused under basal conditions (KR + 3 mmol/L glucose + 1% FFA-free BSA), followed by 0.5 mmol/L PA-containing KR solution for 5 min. Bars on the right represent the average peak amplitude of cytosolic free Ca2+ in the presence of PA. (B) Average curve of ER luminal and (C) mitochondrial Ca2+ dynamics in control and GPx8 cells transfected with the site-specific FRET-based Ca2+ sensors D1ER or 4mtD3cpv before and after perifusion with 0.5 mmol/L PA. The respective bars show the average depletion of ER luminal Ca2+ and the average peak amplitude of mitochondrial Ca2+ levels in the presence of PA, respectively. Data are means ± SEM of 7–10 independent experiments; *p < .05, **p < .01, ***p < .001 compared with INS-1E control cells (Student's t-test, unpaired, two-tailed).
    Figure Legend Snippet: FIGURE 1 Expression of the ER- resident GPx8 attenuates palmitate (PA)- mediated perturbation of intraorganellar Ca2+ dynamics. (A) Average trace of time-dependent changes in cytosolic free Ca2+ in control and GPx8 expressing INS-1E cells perifused under basal conditions (KR + 3 mmol/L glucose + 1% FFA-free BSA), followed by 0.5 mmol/L PA-containing KR solution for 5 min. Bars on the right represent the average peak amplitude of cytosolic free Ca2+ in the presence of PA. (B) Average curve of ER luminal and (C) mitochondrial Ca2+ dynamics in control and GPx8 cells transfected with the site-specific FRET-based Ca2+ sensors D1ER or 4mtD3cpv before and after perifusion with 0.5 mmol/L PA. The respective bars show the average depletion of ER luminal Ca2+ and the average peak amplitude of mitochondrial Ca2+ levels in the presence of PA, respectively. Data are means ± SEM of 7–10 independent experiments; *p < .05, **p < .01, ***p < .001 compared with INS-1E control cells (Student's t-test, unpaired, two-tailed).

    Techniques Used: Expressing, Control, Transfection, Two Tailed Test

    FIGURE 2 Oxidative metabolism of palmitate (PA) is required for the disruption of ER Ca2+ homeostasis. (A) Average trace of ER Ca2+ dynamics upon continuous perifusion with 0.5 mmol/L 2-BromoPA, followed by 0.5 mmol/L PA in INS-1E cells, and (B) after co-stimulation with 0.5 mmol/L 2-BromoPA +0.5 mmol/L PA. Data are means ± SEM of 3 independent experiments.
    Figure Legend Snippet: FIGURE 2 Oxidative metabolism of palmitate (PA) is required for the disruption of ER Ca2+ homeostasis. (A) Average trace of ER Ca2+ dynamics upon continuous perifusion with 0.5 mmol/L 2-BromoPA, followed by 0.5 mmol/L PA in INS-1E cells, and (B) after co-stimulation with 0.5 mmol/L 2-BromoPA +0.5 mmol/L PA. Data are means ± SEM of 3 independent experiments.

    Techniques Used: Disruption

    FIGURE 3 Expression of the ER-resident GPx8 has no impact on carbachol (CCH) or thapsigargin (TG)-evoked ER Ca2+ depletion. (A and C) Average trace of time-dependent changes in cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells perifused for 5 min under basal conditions (3 mmol/L glucose-containing KR), followed by 5 min perifusion with 0.25 μmol/L TG or 0.1 mmol/L CCH. Bars on the right represent the average peak amplitude of cytosolic free-Ca2+ in the presence of TG or CCH. (B and D) show the average curves of ER luminal free-Ca2+ under the same perifusion conditions. The respective bars show the average depletion of ER luminal Ca2+ in the presence of TG or CCH. Data are means ± SEM of 5–6 independent experiments.
    Figure Legend Snippet: FIGURE 3 Expression of the ER-resident GPx8 has no impact on carbachol (CCH) or thapsigargin (TG)-evoked ER Ca2+ depletion. (A and C) Average trace of time-dependent changes in cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells perifused for 5 min under basal conditions (3 mmol/L glucose-containing KR), followed by 5 min perifusion with 0.25 μmol/L TG or 0.1 mmol/L CCH. Bars on the right represent the average peak amplitude of cytosolic free-Ca2+ in the presence of TG or CCH. (B and D) show the average curves of ER luminal free-Ca2+ under the same perifusion conditions. The respective bars show the average depletion of ER luminal Ca2+ in the presence of TG or CCH. Data are means ± SEM of 5–6 independent experiments.

    Techniques Used: Expressing, Control

    FIGURE 4 Expression of the ER-resident GPx8 diminishes palmitate (PA)-mediated reduction of the Ca2+-ATPase activity. (A) Effects of PA pre-exposure on cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells. Control and GPx8 expressing INS-1E cells were pre-incubated with 0.5 mmol/L PA for 24 h, loaded with the ratiometric Ca2+ indicator Fura-2/AM, and then subjected to perifusion with 0.25 μmol/L TG for 5 min. Each point on the curve represents means ± SEM of 4–6 independent experiments. (B) INS-1E control and GPx8 expressing cells were incubated under control conditions or with PA (0.5 and 1.0 mmol/L). After 24 h, RNA was isolated and relative gene expression of SERCA2b was analyzed by RT-qPCR and normalized to the housekeeping genes ß-actin, peptidylprolyl isomerase A, and ribosomal protein L32. Data are means ± SEM of 4 independent experiments. (C) Representative trace of ER luminal Ca2+ upon perifusion under basal conditions, 1 μmol/L ionomycin for 5 min, 100 μmol/L EGTA for 3 min, followed by 5 min perifusion with 1 mmol/L Ca2+- containing KR in INS-1E control- and GPx8 expression before and after pre-incubation with PA for 4 and 24 h. (D) Half-time (t1/2) of ER Ca2+ reuptake in INS-1E control- and GPx8 expressing cells treated under basal conditions or with PA for 4 or 24 h. Data are means ± SEM of 4 independent experiments; *p < .05, compared with INS-1E control cells (ANOVA/Dunnett's-test).
    Figure Legend Snippet: FIGURE 4 Expression of the ER-resident GPx8 diminishes palmitate (PA)-mediated reduction of the Ca2+-ATPase activity. (A) Effects of PA pre-exposure on cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells. Control and GPx8 expressing INS-1E cells were pre-incubated with 0.5 mmol/L PA for 24 h, loaded with the ratiometric Ca2+ indicator Fura-2/AM, and then subjected to perifusion with 0.25 μmol/L TG for 5 min. Each point on the curve represents means ± SEM of 4–6 independent experiments. (B) INS-1E control and GPx8 expressing cells were incubated under control conditions or with PA (0.5 and 1.0 mmol/L). After 24 h, RNA was isolated and relative gene expression of SERCA2b was analyzed by RT-qPCR and normalized to the housekeeping genes ß-actin, peptidylprolyl isomerase A, and ribosomal protein L32. Data are means ± SEM of 4 independent experiments. (C) Representative trace of ER luminal Ca2+ upon perifusion under basal conditions, 1 μmol/L ionomycin for 5 min, 100 μmol/L EGTA for 3 min, followed by 5 min perifusion with 1 mmol/L Ca2+- containing KR in INS-1E control- and GPx8 expression before and after pre-incubation with PA for 4 and 24 h. (D) Half-time (t1/2) of ER Ca2+ reuptake in INS-1E control- and GPx8 expressing cells treated under basal conditions or with PA for 4 or 24 h. Data are means ± SEM of 4 independent experiments; *p < .05, compared with INS-1E control cells (ANOVA/Dunnett's-test).

    Techniques Used: Expressing, Activity Assay, Control, Incubation, Isolation, Gene Expression, Quantitative RT-PCR

    FIGURE 5 An intact GPx8 catalytic activity is required for protection against palmitate (PA)-induced ER Ca2+ dysregulation and toxicity. (A) Scheme depicting the Site-Directed Mutagenesis of GPx8 cysteine 79 by serine and cysteine 108 by alanine, respectively. (B) Immunoblot showing the expression of GPx8 mutant variants in stably transfected INS-1E cells compared to control cells. (C) Control INS-1E, GPx8-WT, GPx8C79S, and GPx8C79S/C108A transfected INS-1E cells were incubated under control conditions or with increasing PA concentrations for 24 h. Thereafter, viability was determined by MTT assay. Data are means ± SEM of 4–6 independent experiments; *p < .05, **p < .01, compared with control cells incubated under the same conditions (Student's t-test, unpaired, two-tailed). Average trace of time-dependent changes in ER- (D) and mitochondrial Ca2+ (E) in control and INS-1E cells expressing either GPx8C79S or GPx8C79S/C108A upon perifusion with PA. Data are means ± SEM of 3 independent experiments.
    Figure Legend Snippet: FIGURE 5 An intact GPx8 catalytic activity is required for protection against palmitate (PA)-induced ER Ca2+ dysregulation and toxicity. (A) Scheme depicting the Site-Directed Mutagenesis of GPx8 cysteine 79 by serine and cysteine 108 by alanine, respectively. (B) Immunoblot showing the expression of GPx8 mutant variants in stably transfected INS-1E cells compared to control cells. (C) Control INS-1E, GPx8-WT, GPx8C79S, and GPx8C79S/C108A transfected INS-1E cells were incubated under control conditions or with increasing PA concentrations for 24 h. Thereafter, viability was determined by MTT assay. Data are means ± SEM of 4–6 independent experiments; *p < .05, **p < .01, compared with control cells incubated under the same conditions (Student's t-test, unpaired, two-tailed). Average trace of time-dependent changes in ER- (D) and mitochondrial Ca2+ (E) in control and INS-1E cells expressing either GPx8C79S or GPx8C79S/C108A upon perifusion with PA. Data are means ± SEM of 3 independent experiments.

    Techniques Used: Activity Assay, Mutagenesis, Western Blot, Expressing, Stable Transfection, Transfection, Control, Incubation, MTT Assay, Two Tailed Test

    FIGURE 8 Summary illustration showing the role of luminal H2O2 in the dysregulation of ER Ca2+ homeostasis unteder lipotoxic conditions. Elevated palmitate concentrations contibuted to increased luminal H2O2 levels that promoted ER Ca2+ depletion by inhibiting SERCA pump actvity. Excessive ER Ca2+ effux affected mitochondrial function manifested by depolarized mitochondrial membrane potential and lowered ATP production. Scavenging of luminal H2O2 by ER-specific antioxidative enzyme GPx8 attanuated palmitate-induced pertubations of intraorganellar Ca2+ dynamics preserved insulin synthesis and mitochondrial function under lipotoxic conditions.
    Figure Legend Snippet: FIGURE 8 Summary illustration showing the role of luminal H2O2 in the dysregulation of ER Ca2+ homeostasis unteder lipotoxic conditions. Elevated palmitate concentrations contibuted to increased luminal H2O2 levels that promoted ER Ca2+ depletion by inhibiting SERCA pump actvity. Excessive ER Ca2+ effux affected mitochondrial function manifested by depolarized mitochondrial membrane potential and lowered ATP production. Scavenging of luminal H2O2 by ER-specific antioxidative enzyme GPx8 attanuated palmitate-induced pertubations of intraorganellar Ca2+ dynamics preserved insulin synthesis and mitochondrial function under lipotoxic conditions.

    Techniques Used: Membrane

    Related Articles

    Plasmid Preparation:

    Article Title: Luminal <scp> H <sub>2</sub> O <sub>2</sub> </scp> promotes <scp>ER</scp> Ca <sup>2+</sup> dysregulation and toxicity of palmitate in insulin‐secreting <scp>INS‐1E</scp> cells
    Article Snippet: .. ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)). .. 1 × 106 cells were nucleofected with 3 μg of the respective Ca2+ biosensor using the Neon Nucleofection System (Thermo Fisher Scientific) and cultured for 48 h prior to perifusion experiments.



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    Addgene inc fret based ca2 biosensor camelon d1er
    FIGURE 1 Expression of the ER- resident GPx8 attenuates palmitate (PA)- mediated perturbation of intraorganellar <t>Ca2+</t> dynamics. (A) Average trace of time-dependent changes in cytosolic free Ca2+ in control and GPx8 expressing INS-1E cells perifused under basal conditions (KR + 3 mmol/L glucose + 1% FFA-free BSA), followed by 0.5 mmol/L PA-containing KR solution for 5 min. Bars on the right represent the average peak amplitude of cytosolic free Ca2+ in the presence of PA. (B) Average curve of ER luminal and (C) mitochondrial Ca2+ dynamics in control and GPx8 cells transfected with the site-specific <t>FRET-based</t> Ca2+ sensors <t>D1ER</t> or 4mtD3cpv before and after perifusion with 0.5 mmol/L PA. The respective bars show the average depletion of ER luminal Ca2+ and the average peak amplitude of mitochondrial Ca2+ levels in the presence of PA, respectively. Data are means ± SEM of 7–10 independent experiments; *p < .05, **p < .01, ***p < .001 compared with INS-1E control cells (Student's t-test, unpaired, two-tailed).
    Fret Based Ca2 Biosensor Camelon D1er, supplied by Addgene inc, used in various techniques. Bioz Stars score: 93/100, based on 1 PubMed citations. ZERO BIAS - scores, article reviews, protocol conditions and more
    https://www.bioz.com/product/fret+based+ca2+biosensor+camelon+d1er/pcDNA-D1ER+(Plasmid+%2336325)/10__1096_slash_fj__202201237r-59-13-29
    Average 93 stars, based on 1 article reviews
    fret based ca2 biosensor camelon d1er - by Bioz Stars, 2026-09
    93/100 stars
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    FIGURE 1 Expression of the ER- resident GPx8 attenuates palmitate (PA)- mediated perturbation of intraorganellar Ca2+ dynamics. (A) Average trace of time-dependent changes in cytosolic free Ca2+ in control and GPx8 expressing INS-1E cells perifused under basal conditions (KR + 3 mmol/L glucose + 1% FFA-free BSA), followed by 0.5 mmol/L PA-containing KR solution for 5 min. Bars on the right represent the average peak amplitude of cytosolic free Ca2+ in the presence of PA. (B) Average curve of ER luminal and (C) mitochondrial Ca2+ dynamics in control and GPx8 cells transfected with the site-specific FRET-based Ca2+ sensors D1ER or 4mtD3cpv before and after perifusion with 0.5 mmol/L PA. The respective bars show the average depletion of ER luminal Ca2+ and the average peak amplitude of mitochondrial Ca2+ levels in the presence of PA, respectively. Data are means ± SEM of 7–10 independent experiments; *p < .05, **p < .01, ***p < .001 compared with INS-1E control cells (Student's t-test, unpaired, two-tailed).

    Journal: The FASEB Journal

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    doi: 10.1096/fj.202201237r

    Figure Lengend Snippet: FIGURE 1 Expression of the ER- resident GPx8 attenuates palmitate (PA)- mediated perturbation of intraorganellar Ca2+ dynamics. (A) Average trace of time-dependent changes in cytosolic free Ca2+ in control and GPx8 expressing INS-1E cells perifused under basal conditions (KR + 3 mmol/L glucose + 1% FFA-free BSA), followed by 0.5 mmol/L PA-containing KR solution for 5 min. Bars on the right represent the average peak amplitude of cytosolic free Ca2+ in the presence of PA. (B) Average curve of ER luminal and (C) mitochondrial Ca2+ dynamics in control and GPx8 cells transfected with the site-specific FRET-based Ca2+ sensors D1ER or 4mtD3cpv before and after perifusion with 0.5 mmol/L PA. The respective bars show the average depletion of ER luminal Ca2+ and the average peak amplitude of mitochondrial Ca2+ levels in the presence of PA, respectively. Data are means ± SEM of 7–10 independent experiments; *p < .05, **p < .01, ***p < .001 compared with INS-1E control cells (Student's t-test, unpaired, two-tailed).

    Article Snippet: ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)).

    Techniques: Expressing, Control, Transfection, Two Tailed Test

    FIGURE 2 Oxidative metabolism of palmitate (PA) is required for the disruption of ER Ca2+ homeostasis. (A) Average trace of ER Ca2+ dynamics upon continuous perifusion with 0.5 mmol/L 2-BromoPA, followed by 0.5 mmol/L PA in INS-1E cells, and (B) after co-stimulation with 0.5 mmol/L 2-BromoPA +0.5 mmol/L PA. Data are means ± SEM of 3 independent experiments.

    Journal: The FASEB Journal

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    doi: 10.1096/fj.202201237r

    Figure Lengend Snippet: FIGURE 2 Oxidative metabolism of palmitate (PA) is required for the disruption of ER Ca2+ homeostasis. (A) Average trace of ER Ca2+ dynamics upon continuous perifusion with 0.5 mmol/L 2-BromoPA, followed by 0.5 mmol/L PA in INS-1E cells, and (B) after co-stimulation with 0.5 mmol/L 2-BromoPA +0.5 mmol/L PA. Data are means ± SEM of 3 independent experiments.

    Article Snippet: ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)).

    Techniques: Disruption

    FIGURE 3 Expression of the ER-resident GPx8 has no impact on carbachol (CCH) or thapsigargin (TG)-evoked ER Ca2+ depletion. (A and C) Average trace of time-dependent changes in cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells perifused for 5 min under basal conditions (3 mmol/L glucose-containing KR), followed by 5 min perifusion with 0.25 μmol/L TG or 0.1 mmol/L CCH. Bars on the right represent the average peak amplitude of cytosolic free-Ca2+ in the presence of TG or CCH. (B and D) show the average curves of ER luminal free-Ca2+ under the same perifusion conditions. The respective bars show the average depletion of ER luminal Ca2+ in the presence of TG or CCH. Data are means ± SEM of 5–6 independent experiments.

    Journal: The FASEB Journal

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    doi: 10.1096/fj.202201237r

    Figure Lengend Snippet: FIGURE 3 Expression of the ER-resident GPx8 has no impact on carbachol (CCH) or thapsigargin (TG)-evoked ER Ca2+ depletion. (A and C) Average trace of time-dependent changes in cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells perifused for 5 min under basal conditions (3 mmol/L glucose-containing KR), followed by 5 min perifusion with 0.25 μmol/L TG or 0.1 mmol/L CCH. Bars on the right represent the average peak amplitude of cytosolic free-Ca2+ in the presence of TG or CCH. (B and D) show the average curves of ER luminal free-Ca2+ under the same perifusion conditions. The respective bars show the average depletion of ER luminal Ca2+ in the presence of TG or CCH. Data are means ± SEM of 5–6 independent experiments.

    Article Snippet: ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)).

    Techniques: Expressing, Control

    FIGURE 4 Expression of the ER-resident GPx8 diminishes palmitate (PA)-mediated reduction of the Ca2+-ATPase activity. (A) Effects of PA pre-exposure on cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells. Control and GPx8 expressing INS-1E cells were pre-incubated with 0.5 mmol/L PA for 24 h, loaded with the ratiometric Ca2+ indicator Fura-2/AM, and then subjected to perifusion with 0.25 μmol/L TG for 5 min. Each point on the curve represents means ± SEM of 4–6 independent experiments. (B) INS-1E control and GPx8 expressing cells were incubated under control conditions or with PA (0.5 and 1.0 mmol/L). After 24 h, RNA was isolated and relative gene expression of SERCA2b was analyzed by RT-qPCR and normalized to the housekeeping genes ß-actin, peptidylprolyl isomerase A, and ribosomal protein L32. Data are means ± SEM of 4 independent experiments. (C) Representative trace of ER luminal Ca2+ upon perifusion under basal conditions, 1 μmol/L ionomycin for 5 min, 100 μmol/L EGTA for 3 min, followed by 5 min perifusion with 1 mmol/L Ca2+- containing KR in INS-1E control- and GPx8 expression before and after pre-incubation with PA for 4 and 24 h. (D) Half-time (t1/2) of ER Ca2+ reuptake in INS-1E control- and GPx8 expressing cells treated under basal conditions or with PA for 4 or 24 h. Data are means ± SEM of 4 independent experiments; *p < .05, compared with INS-1E control cells (ANOVA/Dunnett's-test).

    Journal: The FASEB Journal

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    doi: 10.1096/fj.202201237r

    Figure Lengend Snippet: FIGURE 4 Expression of the ER-resident GPx8 diminishes palmitate (PA)-mediated reduction of the Ca2+-ATPase activity. (A) Effects of PA pre-exposure on cytosolic free-Ca2+ in control and GPx8 expressing INS-1E cells. Control and GPx8 expressing INS-1E cells were pre-incubated with 0.5 mmol/L PA for 24 h, loaded with the ratiometric Ca2+ indicator Fura-2/AM, and then subjected to perifusion with 0.25 μmol/L TG for 5 min. Each point on the curve represents means ± SEM of 4–6 independent experiments. (B) INS-1E control and GPx8 expressing cells were incubated under control conditions or with PA (0.5 and 1.0 mmol/L). After 24 h, RNA was isolated and relative gene expression of SERCA2b was analyzed by RT-qPCR and normalized to the housekeeping genes ß-actin, peptidylprolyl isomerase A, and ribosomal protein L32. Data are means ± SEM of 4 independent experiments. (C) Representative trace of ER luminal Ca2+ upon perifusion under basal conditions, 1 μmol/L ionomycin for 5 min, 100 μmol/L EGTA for 3 min, followed by 5 min perifusion with 1 mmol/L Ca2+- containing KR in INS-1E control- and GPx8 expression before and after pre-incubation with PA for 4 and 24 h. (D) Half-time (t1/2) of ER Ca2+ reuptake in INS-1E control- and GPx8 expressing cells treated under basal conditions or with PA for 4 or 24 h. Data are means ± SEM of 4 independent experiments; *p < .05, compared with INS-1E control cells (ANOVA/Dunnett's-test).

    Article Snippet: ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)).

    Techniques: Expressing, Activity Assay, Control, Incubation, Isolation, Gene Expression, Quantitative RT-PCR

    FIGURE 5 An intact GPx8 catalytic activity is required for protection against palmitate (PA)-induced ER Ca2+ dysregulation and toxicity. (A) Scheme depicting the Site-Directed Mutagenesis of GPx8 cysteine 79 by serine and cysteine 108 by alanine, respectively. (B) Immunoblot showing the expression of GPx8 mutant variants in stably transfected INS-1E cells compared to control cells. (C) Control INS-1E, GPx8-WT, GPx8C79S, and GPx8C79S/C108A transfected INS-1E cells were incubated under control conditions or with increasing PA concentrations for 24 h. Thereafter, viability was determined by MTT assay. Data are means ± SEM of 4–6 independent experiments; *p < .05, **p < .01, compared with control cells incubated under the same conditions (Student's t-test, unpaired, two-tailed). Average trace of time-dependent changes in ER- (D) and mitochondrial Ca2+ (E) in control and INS-1E cells expressing either GPx8C79S or GPx8C79S/C108A upon perifusion with PA. Data are means ± SEM of 3 independent experiments.

    Journal: The FASEB Journal

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    doi: 10.1096/fj.202201237r

    Figure Lengend Snippet: FIGURE 5 An intact GPx8 catalytic activity is required for protection against palmitate (PA)-induced ER Ca2+ dysregulation and toxicity. (A) Scheme depicting the Site-Directed Mutagenesis of GPx8 cysteine 79 by serine and cysteine 108 by alanine, respectively. (B) Immunoblot showing the expression of GPx8 mutant variants in stably transfected INS-1E cells compared to control cells. (C) Control INS-1E, GPx8-WT, GPx8C79S, and GPx8C79S/C108A transfected INS-1E cells were incubated under control conditions or with increasing PA concentrations for 24 h. Thereafter, viability was determined by MTT assay. Data are means ± SEM of 4–6 independent experiments; *p < .05, **p < .01, compared with control cells incubated under the same conditions (Student's t-test, unpaired, two-tailed). Average trace of time-dependent changes in ER- (D) and mitochondrial Ca2+ (E) in control and INS-1E cells expressing either GPx8C79S or GPx8C79S/C108A upon perifusion with PA. Data are means ± SEM of 3 independent experiments.

    Article Snippet: ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)).

    Techniques: Activity Assay, Mutagenesis, Western Blot, Expressing, Stable Transfection, Transfection, Control, Incubation, MTT Assay, Two Tailed Test

    FIGURE 8 Summary illustration showing the role of luminal H2O2 in the dysregulation of ER Ca2+ homeostasis unteder lipotoxic conditions. Elevated palmitate concentrations contibuted to increased luminal H2O2 levels that promoted ER Ca2+ depletion by inhibiting SERCA pump actvity. Excessive ER Ca2+ effux affected mitochondrial function manifested by depolarized mitochondrial membrane potential and lowered ATP production. Scavenging of luminal H2O2 by ER-specific antioxidative enzyme GPx8 attanuated palmitate-induced pertubations of intraorganellar Ca2+ dynamics preserved insulin synthesis and mitochondrial function under lipotoxic conditions.

    Journal: The FASEB Journal

    Article Title: Luminal H 2 O 2 promotes ER Ca 2+ dysregulation and toxicity of palmitate in insulin‐secreting INS‐1E cells

    doi: 10.1096/fj.202201237r

    Figure Lengend Snippet: FIGURE 8 Summary illustration showing the role of luminal H2O2 in the dysregulation of ER Ca2+ homeostasis unteder lipotoxic conditions. Elevated palmitate concentrations contibuted to increased luminal H2O2 levels that promoted ER Ca2+ depletion by inhibiting SERCA pump actvity. Excessive ER Ca2+ effux affected mitochondrial function manifested by depolarized mitochondrial membrane potential and lowered ATP production. Scavenging of luminal H2O2 by ER-specific antioxidative enzyme GPx8 attanuated palmitate-induced pertubations of intraorganellar Ca2+ dynamics preserved insulin synthesis and mitochondrial function under lipotoxic conditions.

    Article Snippet: ER- luminal and mitochondrial Ca2+ fluctuations were measured by site- specific genetically encoded FRET- based Ca2+ biosensor Camelon D1ER and 4mtD3cpv (kind gift from Amy Palmer & Roger Tsien (Addgene plasmid #36325; http://n2t.net/addge ne:36325; RRID: Addgene_36325 and Addgene plasmid #36324; http:// n2t.net/addge ne:36324; RRID: Addgene_36324)).

    Techniques: Membrane