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Estrogen receptor α (ERα) action plays an important role in pancreatic β-cell function and survival; thus, it is considered a potential therapeutic target for the treatment of type 2 diabetes in women. However, the mechanisms underlying the protective effects of ERα remain unclear. Because ERα regulates mitochondrial metabolism in other cell types, we hypothesized that ERα may act to preserve insulin secretion and promote β-cell survival by regulating mitochondrial-endoplasmic reticulum (EndoRetic) function. We tested this hypothesis using pancreatic islet-specific ERα knockout (PERαKO) mice and Min6 β-cells in culture with Esr1 knockdown (KD). We found that Esr1-KD promoted reactive oxygen species production that associated with reduced fission/fusion dynamics and impaired mitophagy. Electron microscopy showed mitochondrial enlargement and a pro-fusion phenotype. Mitochondrial cristae and endoplasmic reticulum were dilated in Esr1-KD compared with ERα replete Min6 β-cells. Increased expression of Oma1 and Chop was paralleled by increased oxygen consumption and apoptosis susceptibility in ERα-KD cells. In contrast, ERα overexpression and ligand activation reduced both Chop and Oma1 expression, likely by ERα binding to consensus estrogen-response element sites in the Oma1 and Chop promoters. Together, our findings suggest that ERα promotes β-cell survival and insulin secretion through maintenance of mitochondrial fission/fusion-mitophagy dynamics and EndoRetic function, in part by Oma1 and Chop repression.

Estrogen receptor α (ERα) action plays an important role in pancreatic β-cell function and survival; thus, it is considered a potential therapeutic target for the treatment of type 2 diabetes in women. However, the mechanisms underlying the protective effects of ERα remain unclear. Because ERα regulates mitochondrial metabolism in other cell types, we hypothesized that ERα may act to preserve insulin secretion and promote β-cell survival by regulating mitochondrial-endoplasmic reticulum (EndoRetic) function. We tested this hypothesis using pancreatic islet-specific ERα knockout (PERαKO) mice and Min6 β-cells in culture with Esr1 knockdown (KD). We found that Esr1-KD promoted reactive oxygen species production that associated with reduced fission/fusion dynamics and impaired mitophagy. Electron microscopy showed mitochondrial enlargement and a pro-fusion phenotype. Mitochondrial cristae and endoplasmic reticulum were dilated in Esr1-KD compared with ERα replete Min6 β-cells. Increased expression of Oma1 and Chop was paralleled by increased oxygen consumption and apoptosis susceptibility in ERα-KD cells. In contrast, ERα overexpression and ligand activation reduced both Chop and Oma1 expression, likely by ERα binding to consensus estrogen-response element sites in the Oma1 and Chop promoters. Together, our findings suggest that ERα promotes β-cell survival and insulin secretion through maintenance of mitochondrial fission/fusion-mitophagy dynamics and EndoRetic function, in part by Oma1 and Chop repression.

AimsIn individuals with chronic kidney disease (CKD), including those undergoing maintenance hemodialysis (MHD), coronary artery calcification (CAC) is common. We hypothesized that, in MHD patients, intake of the calcium-free phosphate binder sevelamer is associated with lower CAC compared to calcium-based phosphate binders (CBPB).Material and methodsThis is a cross-sectional study of MHD patients, who underwent computerized tomography to assess coronary artery calcium scores (CACS). Patients were stratified into two mutually exclusive groups based on taking only a CBPB vs. sevelamer. Logistic regression was used to calculate adjusted odds ratio (OR) of CACS > or = 400, CACS 100 < or =; CACS < 400, 10 < or =; CACS < 100 vs. CACS < 10.Results117 MHD patients were either on a CBPB alone (n = 60) or sevelamer alone (n = 57). Despite increased prevalence of DM in the sevelamer group (58%) as compared to the CBPB group (35%), CACS was significantly lower with sevelamer use (283 + or - 83 vs. 494 + or - 94, p = 0.02). The OR of significant CACS > or =; 400 vs. CAC < 10 was 4.35 (95% confidence interval: 1.5 - 9.9, p = 0.008) for CBPB compared with sevelamer, after controlling for case-mix, cholesterol-lowering medication, DM, and inflammatory markers.ConclusionIn our cohort, significant CAC was significantly more prevalent among MHD patients taking CBPB as compared to sevelamer monotherapy.

AimsIn individuals with chronic kidney disease (CKD), including those undergoing maintenance hemodialysis (MHD), coronary artery calcification (CAC) is common. We hypothesized that, in MHD patients, intake of the calcium-free phosphate binder sevelamer is associated with lower CAC compared to calcium-based phosphate binders (CBPB).Material and methodsThis is a cross-sectional study of MHD patients, who underwent computerized tomography to assess coronary artery calcium scores (CACS). Patients were stratified into two mutually exclusive groups based on taking only a CBPB vs. sevelamer. Logistic regression was used to calculate adjusted odds ratio (OR) of CACS > or = 400, CACS 100 < or =; CACS < 400, 10 < or =; CACS < 100 vs. CACS < 10.Results117 MHD patients were either on a CBPB alone (n = 60) or sevelamer alone (n = 57). Despite increased prevalence of DM in the sevelamer group (58%) as compared to the CBPB group (35%), CACS was significantly lower with sevelamer use (283 + or - 83 vs. 494 + or - 94, p = 0.02). The OR of significant CACS > or =; 400 vs. CAC < 10 was 4.35 (95% confidence interval: 1.5 - 9.9, p = 0.008) for CBPB compared with sevelamer, after controlling for case-mix, cholesterol-lowering medication, DM, and inflammatory markers.ConclusionIn our cohort, significant CAC was significantly more prevalent among MHD patients taking CBPB as compared to sevelamer monotherapy.

IntroductionCardiovascular disease accounts for almost half of all deaths in individuals with chronic kidney disease stage 5 despite advances in both dialysis treatment and cardiology. A combination of lipid-lowering and anti-inflammatory effects along with avoidance of hypercalcemia should be taken into account when choosing phosphorus binders for maintenance hemodialysis (MHD) patients.MethodsWe examined the association of sevelamer versus calcium-based phosphorus binders with lipid profile, inflammatory markers including C-reactive protein (CRP), and mineral metabolism in MHD patients who participated in the Nutritional and Inflammatory Evaluation of Dialysis Patients (NIED) study from October 2001 to July 2005.ResultsOf the 787 MHD patients in the NIED study, 697 were on either sevelamer, a calcium-based binder, or both and eligible for this study. We compared the groups based on taking sevelamer monotherapy (n = 283) or calcium binder monotherapy (n = 266) for serum phosphate control. There were no differences between the groups on dialysis vintage. There were significant differences in age, serum calcium and phosphorus levels, as well as intact parathyroid hormone levels. Using a logistic regression models, the sevelamer group had a higher odds of serum CRP

IntroductionCardiovascular disease accounts for almost half of all deaths in individuals with chronic kidney disease stage 5 despite advances in both dialysis treatment and cardiology. A combination of lipid-lowering and anti-inflammatory effects along with avoidance of hypercalcemia should be taken into account when choosing phosphorus binders for maintenance hemodialysis (MHD) patients.MethodsWe examined the association of sevelamer versus calcium-based phosphorus binders with lipid profile, inflammatory markers including C-reactive protein (CRP), and mineral metabolism in MHD patients who participated in the Nutritional and Inflammatory Evaluation of Dialysis Patients (NIED) study from October 2001 to July 2005.ResultsOf the 787 MHD patients in the NIED study, 697 were on either sevelamer, a calcium-based binder, or both and eligible for this study. We compared the groups based on taking sevelamer monotherapy (n = 283) or calcium binder monotherapy (n = 266) for serum phosphate control. There were no differences between the groups on dialysis vintage. There were significant differences in age, serum calcium and phosphorus levels, as well as intact parathyroid hormone levels. Using a logistic regression models, the sevelamer group had a higher odds of serum CRP