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Background/Aims: VCP-interacting membrane selenoprotein (VIMP), an ER resident selenoprotein, is highly expressed in β-cells, however, the role of VIMP in β-cells has not been characterized. In this study, we studied the relationship between VIMP deficiency and β-cell survival in MIN6 insulinoma cells. Methods: To determine the role of VIMP in β-cells, lentiviral VIMP shRNAs were used to knock down (KD) expression of VIMP in MIN6 cells. Cell death was quantified by propidium iodide (PI) staining followed by flow cytometric analyses using a FACS Caliber and FlowJo software. Cell apoptosis and proliferation were determined by TUNEL assay and Ki67 staining, respectively. Cell cycle was analyzed after PI staining. Results: The results show that 1) VIMP suppression induces β-cell apoptosis, which is associated with a decrease in Bcl-xL, and the β-cell apoptosis induced by VIMP suppression can be inhibited by overexpression of Bcl-xL; 2) VIMP knockdown (KD) decreases cell proliferation and G1 cell cycle arrest by accumulating p27 and decreasing E2F1; 3) VIMP KD suppresses unfolded protein response (UPR) activation by regulating the IRE1α and PERK pathways; 4) VIMP KD increases insulin secretion. Conclusion: These results suggest that VIMP may function as a novel regulator to modulate β-cell survival, proliferation, cell cycle, UPR and insulin secretion in MIN6 cells. [ABSTRACT FROM AUTHOR]

Abstract As the most conserved branch of the unfolded protein response (UPR), the inositol-requiring enzyme 1a (IRE1a)/X-box binding protein 1 (XBP1) pathway plays crucial roles in cell survival and cell death by upregulating UPR-associated genes involved in protein entry into the endoplasmic reticulum (ER) and ER-associated degradation (ERAD). Selenoprotein S (SelS) is localized to the ER membrane and involved in ERAD. Although SelS plays an important role in restoring ER stress, the SelS-dependent protective mechanisms against cell death remain unclear. Here, using an inducible SelS knockdown (KD) 3T3-L1 cell model, we showed that SelS KD resulted adipocyte death, which was associated with imbalance of the Bcl-2 family members. Furthermore, SelS KD decreased spliced XBP1 (sXBP1), increased IRE1α and p -JNK, suggesting a role of SelS in the modulation of the IRE1α-sXBP1 pathway. Moreover, adipocyte death induced by SelS suppression can be inhibited by overexpression of sXBP1. Thus, it is proposed that SelS promotes cell survival through the IRE1α-XBP1 signaling pathway. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction, partly induced by inflammatory mediators, is known to initiate and promote several cardiovascular diseases. Selenoprotein S (SelS) has been identified in endothelial cells and is associated with inflammation; however, its function in inflammation-induced endothelial dysfunction has not been described. We first demonstrated that the upregulation of SelS enhances the levels of nitric oxide and endothelial nitric oxide synthase in tumor necrosis factor- (TNF-) α-treated human umbilical vein endothelial cells (HUVECs). The levels of TNF-α-induced endothelin-1 and reactive oxygen species are also reduced by the upregulation of SelS. Furthermore, SelS overexpression blocks the TNF-α-induced adhesion of THP-1 cells to HUVECs and inhibits the increase in intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Moreover, SelS overexpression regulates TNF-α-induced inflammatory factors including interleukin-1β, interleukin-6, interleukin-8, and monocyte chemotactic protein-1 and attenuates the TNF-α-induced activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways. Conversely, the knockdown of SelS with siRNA results in an enhancement of TNF-α-induced injury in HUVECs. These findings suggest that SelS protects endothelial cells against TNF-α-induced dysfunction by inhibiting the activation of p38 MAPK and NF-κB pathways and implicates it as a possible modulator of vascular inflammatory diseases. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the impact of dynamic changes in inflammation on atherosclerosis in short-duration type 2 diabetes after multifactorial intervention.Methods: In this randomized controlled study, a total of 150 type 2 diabetes patients who had a mean age of 49.8±7.3years, 51% male, with disease duration <1year and without evidence of atherosclerosis were randomized into an intensive intervention group (IG), in which patients received multiple risk factors intervention by the special project team and tried to reach the pre-determined intervention goals, and a conventional group (CG), in which patients received standard diabetes care by the clinic doctor. All patients recieved intervention study for 7 years, then underwent a 3-year observational follow-up study. The primary endpoints were occurrence of subclinical atherosclerosis, defined as the intima-media thickness of the common carotid artery (CC-IMT)≥1.0mm or formation of atherosclerosis plaques, and the occurrence of cardiovascular events.Results: 68 patients in IG and 65 patients in CG completed the 10-year study. The cumulative incidence of subclinical atherosclerosis was 30.7% vs 57.3% (IG vs CG, HR 0.36, 95% CI 0.22-0.60, P<0.0001) and that of cardiovascular events was 12.0% vs 22.7% (IG vs CG, HR 0.46, 95% CI 0.21-0.98, P=0.0516). High sensitivity C-reactive protein (hs-CRP) reduction from baseline to the 10-year follow-up was -1.54mg/L (IG) and -0.67mg/L (CG) with difference (IG minus CG) of -0.87mg/L(95% CI -0.72 to -1.02, P=0.008) and the natural logarithm of serum amyloid A (SAA) reduction was -4.04 (IG) and -1.44 (CG) with difference (IG minus CG) of -2.60 (95% CI -2.30 to -2.90, P=0.002). The decrease in general score of inflammatory markers (combination of hs-CRP and SAA) was independently associated with subclinical atherosclerosis (OR=0.65, P=0.045) and cardiovascular events (OR=0.60, P=0.042).Conclusions: Dynamic changes in inflammation act as an important factor that affects the occurrence of atherosclerosis in type 2 diabetes patients. Multifactorial intensive intervention can reduce systemic low-grade inflammation and delay the occurrence of atherosclerosis in short-duration type 2 diabetes. [ABSTRACT FROM AUTHOR]

Objective To investigate the relationship between serum selenoprotein S (SelS) and obesity in patients with type 2 diabetes mellitus (T2DM). Methods Two hundred and nine T2DM patients who were managed by the National Metabolic Management Center (MMC) of the First Affiliated Hospital of Dalian Medical University from November 2017 to November 2019 and 55 healthy people as controls in the health examination center of our hospital were enrolled in the retrospective cross-sectional study. The general condition, biochemical indexes and obesity evaluation parameters were recorded. According to the serum SelS quartile, T2DM patients were divided into Q1 group: ≤95.10 ng/dl (53 cases), Q2 group: 95.12 to 111.62 ng/dl (52 cases), Q3 group: 112.46 to 130.97 ng/dl (52 cases), Q4 group: ≥131.33 ng/dl (52 cases). Analysis of variances, rank sum test and Chi-square test were used for comparison between groups. Multiple stepwise regression was used to analyze the influencing factors of obesity evaluation index. Results There was statistically significant difference in visceral fat index (VAI) among T2DM abdominal obesity group, non-abdominal obesity group and healthy control group (H=36.679, P<0.01), but there was no statistically significant difference in serum SelS. There was statistically significant difference in serum amyloid A (SAA) level among the SelS quartile groups (H=3.560, P<0.01), but there was no statistically significant difference in visceral fat area (VFA), subcutaneous fat area (SFA), visceral fat area to subcutaneous fat area ratio (VSR) and VAI. Serum SelS was positively correlated with VFA, VSR, VAI and SAA (r=0.158 to 0.448, all P<0.05). Serum SelS was an independent risk factor for VFA (β= 0.172, P=0.003), VSR (β=0.001, P=0.01) and VAI (β=0.009, P=0.038). Conclusion Serum SelS level in T2DM patients is positively correlated with VFA, VSR and VAI, which is an independent risk factor for abdominal obesity. [ABSTRACT FROM AUTHOR]

N6-methyladenosine (m6A) is the most abundant mRNA modification. However, the role of m6A in regulating β-cell function is unknown. To address the functional role of METTL14, a key component of the m6A methyltransferase complex, in β-cells, we generated an METTL14 β-cell specific knockout mouse in adult MIP-CreERT transgenic mice. 4 weeks after tamoxifen treatment (100 mg/kg for 3 times every other day), the feeding glucose of βKO mice were 55.1% higher in βKO mice. βKO mice are also glucose intolerant. The AUC was increased by 54.7% in βKO mice (P<0.01). The fasting glucose were 307.5 ± 24.3 mg/dl in βKO mice and 219.0 ± 7.8 mg/dl in control mice (P<0.001). The response to insulin was similar between βKO and control mice. The feeding insulin levels in βKO mice were significantly decreased by 58.9% (P<0.01). The serum insulin levels from βKO mice were significantly lower at 0, 15 and 30 minutes after glucose challenge. In addition, the insulin secretion from βKO islets was less than 50% of control islets after incubated at 16.7 mM glucose. Surprisingly, β-cell mass in βKO mice was 55.9% higher than that in control mice (P<0.05). In addition, we did not detect β-cell death in βKO islets. However, β-cell proliferation in βKO islets was increased by 1.3-fold. To understand the molecular mechanism, we performed RNA-seq to detect the gene expression in βKO and control islets from male mice 8 weeks after tamoxifen treatment. Among 106 altered genes in βKO islets, 104 genes were upregulated (P<0.001) and 2 genes were downregulated. The genes response to ER stress such as Pdia4, Itpr1, Thbs1, Ire1α and Igfbp5 were among the top up-regulated genes. We applied m6A-seq in MIN6 cells and confirmed that Ire1α was modified by m6A in its last exon and 3' UTR region. We further showed that both mRNA and protein of Ire1α and spliced XBP-1 were significantly increased in βKO islets. In conclusion, METTL14 plays an important role in regulating insulin secretion, and METTL14 deficiency in β-cells induces diabetes by increasing ER stress. Disclosure: L. Men: None. J. Sun: None. D. Ren: None. Funding: National Institutes of Health (P30DK020595) [ABSTRACT FROM AUTHOR]

The transport of materials and energy between rivers and riparian zones are driven by lateral hyporheic exchange and plays a vital role in regulating the ecological health of rivers. Owing to the limitations of models and methods, prior research has mainly focused on vertical hyporheic exchange in river systems. Combined with the collected riparian zone temperature and water level data, a 2D hydrothermal coupling model of the riparian zone was developed using the thermal conductivity model, and the fitting effects of the Lu et al. (2007) model and Su et al. (2016) model on temperature variations in riparian zone comparatively analyzed. Then, the dynamic variation characteristics of the riparian zone temperature and the lateral hyporheic exchange recharge pattern were investigated by the constructed models. The calibrated model could reasonably illustrate the variations in the riparian zone temperature, and the sensitivity analysis revealed that the hydraulic conductivity (Ks) is the most sensitive factor to the temperature variations. [ABSTRACT FROM AUTHOR]

Ren, J.; Chen, B.; Li, Y.; Dai, J., and Men, L., 2020. Dynamic variation characteristics of the riparian zone temperature distribution under fluctuating water levels: Field experiments and numerical modeling. Journal of Coastal Research, 36(6), 1178–1196. Coconut Creek (Florida), ISSN 0749-0208. Understanding the variations in water and heat transfer along the riparian zone under water-level fluctuations is essential for river water management, groundwater extraction, and ecosystem sustainability. The main purpose of this study is to describe the dynamics of the temperature field of the Dongting Lake beach under the fluctuation in the water level and to quantify its main influencing factors. Taking the section of Dongting Lake beach as the research object, an in situ monitoring device was used to monitor the water level, water temperature, and temperature at different depths of the beach in real time for 55 days, and the hydrothermal coupling model of the Dongting Lake beach was calibrated and verified. The main factors affecting the temperature field of the beach were determined by the global sensitivity analysis method. The results show that the fluctuation in the continental beach temperature field is small in the horizontal direction, the stratification phenomenon is obvious in the vertical direction, the temperature gradually rises with increasing depth, and the daily changes are weakened. During the high water level, the deep temperature of the beach has no obvious gradient change in the vertical direction, and as the water level of the river decreases, the external environmental temperature has a greater influence on the internal temperature field of the beach, resulting in a relatively pronounced gradient change in the deep temperature at the low water level. The results of the Morris one at a time global sensitivity analysis show that the permeability coefficient (Ks) has the greatest influence on the sensitivity of the model, followed by the porosity (n) and soil thermal conductivity (λs). The saturated moisture content (θs), residual moisture content (θr), and soil-specific heat capacity (Cs) have no significant effect on the model. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction is an initiating key step for diabetic macrovascular complications, and it is closely related to the hemodynamic microenvironment in vivo. However, diabetic patients usually coexist with other cardiovascular risk factors, and the more powerful targeting strategy for protecting endothelium is still limited. Selenoprotein S (SelS) was found in our previous study that could increase vascular endothelial cells resistance to oxidative stress associated with protein kinase C α (PKCα). Thus, in this study, we constructed a diabetic vascular endothelial bionic microenvironment mimicking hyperglycemia and/or hyperlipidemia based on microfludic chip through modulating the concentration of medium glucose and oxidized low density lipoproteins. Our results showed that under diabetic vascular endothelial bionic microenvironment, the upregulation of SelS enhanced nitric oxide synthase (eNOS) expression and reduced endothelin-1 level in human aortic endothelial cells (HAECs), accompany with increase in cell viability and SOD1 and SOD2 activity, and decrease in ROS. Furthermore, SelS overexpression attenuated the activation of PKCα, which subsequently promoted the activation of PI3K/Akt/eNOS pathway. Conversely, the knockdown of SelS resulted in an enhancement of endothelial injury. These findings suggest that SelS could protect endothelial cells from oxidative stress injury under diabetic vascular endothelial bionic microenvironment through PKCα and PI3K/Akt/eNOS pathway. Our results offer a promising and biomimetic platform for investigation on endothelial protection, and provide evidence of SelS as potential novel target to treat diabetic macrovascular complications. Disclosure: S. Yu: None. Y. Zhong: None. L. Men: None. J. Yao: None. J. Du: None. Funding: National Natural Science Foundation of China (81570727) [ABSTRACT FROM AUTHOR]

Defects in the development, maintenance or expansion of β-cell mass can result in impaired glucose metabolism and diabetes. N 6-methyladenosine affects mRNA stability and translation efficiency, and impacts cell differentiation and stress response. To determine if there is a role for m6A in β-cells, we investigated the effect of Mettl14 , a key component of the m6A methyltransferase complex, on β-cell survival and function using rat insulin-2 promoter-Cre-mediated deletion of Mettl14 mouse line (βKO). We found that βKO mice with normal chow exhibited glucose intolerance, lower levels of glucose-stimulated insulin secretion, increased β-cell death and decreased β-cell mass. In addition, HFD-fed βKO mice developed glucose intolerance, decreased β-cell mass and proliferation, exhibited lower body weight, increased adipose tissue mass, and enhanced insulin sensitivity due to enhanced AKT signaling and decreased gluconeogenesis in the liver. HFD-fed βKO mice also showed a decrease in de novo lipogenesis, and an increase in lipolysis in the liver. RNA sequencing in islets revealed that Mettl14 deficiency in β-cells altered mRNA expression levels of some genes related to cell death and inflammation. Together, we showed that Mettl14 in β-cells plays a key role in β-cell survival, insulin secretion and glucose homeostasis. • Mice with METTL14 deficiency showed glucose intolerance. • β-Cell mass was significantly decreased in β-cell METTL14 deficient mice. • Insulin secretion was decreased in METTL14 deficient mice. • METTL14 deficiency in β-cells impaired compensatory islet expansion on HFD. • Mettl14 deficiency in β-cells altered mRNA levels of cell death and inflammation genes. [ABSTRACT FROM AUTHOR]

As an environmental toxicant, arsenic exposure may cause insulin resistance (IR). Previous studies have shown that pyroptosis plays an important role in the occurrence and development of IR. Although gasdermin D (GSDMD) functions as an executor of pyroptosis, the relationship between GSDMD-mediated pyroptosis and hepatic IR remains unclear. Here, we observed that sodium arsenite (NaAsO 2) activated NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasomes, promoted GSDMD activation, induced pyroptosis and hepatic IR, while GSDMD knockdown attenuated pyroptosis and hepatic IR caused by NaAsO 2. However, GSDMD interference did not affect NLRP3 activation. Ubiquitination modification is widely involved in protein regulation and intracellular signal transduction, and whether it regulates GSDMD and affects its degradation, and exerts effects on arsenic-induced pyroptosis remain unclear. We observed that NaAsO 2 reduced the K48- and K63-linked ubiquitination of GSDMD, thereby inhibiting its degradation through the ubiquitin-proteasome system (UPS) and the autophagy-lysosome pathway (ALP), causing GSDMD to accumulate and lyse into GSDMD-N, which promoted pyroptosis. In summary, we demonstrated that GSDMD participated in arsenic-induced hepatic IR. Moreover, NaAsO 2 reduced GSDMD ubiquitination and decreased its intracellular degradation, aggravating pyroptosis and hepatic IR. We have revealed the molecular mechanism underpinning arsenic-induced IR, and we provide potential solutions for the prevention and treatment of type 2 diabetes (T2D). [Display omitted] • The reduction of GSDMD would attenuate the arsenic-induced pyroptosis and insulin resistance. • Exposure to NaAsO 2 would reduce the ubiquitination level of GSDMD. • Ubiquitinated GSDMD would be degraded by ubiquitin-proteasome system and autophagy-lysosome pathway. [ABSTRACT FROM AUTHOR]

Glucolipid metabolism disorder in diabetes mellitus (DM) causes human endothelial injury and autophagy dysfunction is an important cause of endothelial dysfunction (ED). Selenoprotein S (SelS) could protect endothelium from oxidative stress, inflammatory responses, and apoptosis. This study assessed the effect of SelS on autophagy in glucolipid metabolic disorders and protection of the resulted vascular endothelial injury. The results showed that high glucose (HG), high oxidized low-density lipoprotein (HL), and HG combined with HL (HGL) could reduce viability of human aortic endothelial cells (HAECs), induce HAECs injury and increase SelS expression in a time-dependent manner. HG, HL, and HGL also initially induced autophagy but later reduced it in HAECs, while activity of the Akt/mTOR signaling was inhibited, especially in HGL culture of HAECs. SelS overexpression reduced the endothelial injury and autophagy and activated the Akt/mTOR signaling in HG, HL and HGL-cultured HAECs, compared to the control. Conversely, knockdown of SelS expression had the opposite effects on HAECs. In conclusion, SelS demonstrated a protective effect on endothelial injury induced by high glucose and/or ox-LDL and the underlying molecular events might be related to its regulation of HAECs autophagy by activating the Akt/mTOR signaling. SelS could be a potential intervention target in prevention and treatment of diabetic vascular complications. • Glucolipid metabolism disorder had a synergistic effect on endothelial injury. • Selenoprotein S could attenuate endothelial injury in HAECs. • Selenoprotein S inhibited human aortic endothelial cell autophagy. • Selenoprotein S regulated autophagy through Akt/mTOR signaling. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction (ED) is a critical and initiating factor in the genesis of diabetic vascular complications whose occurrence and development is closely related to the complex intravascular microenvironment. However, currently, there is no dynamic model simulating the diabetic vascular endothelial microenvironment that can be used to investigate the mechanism underlying multifactor-induced ED. Here, we developed an integrated microfluidic chip as a new methodological platform to study vascular ED. Selenoprotein S (SELENOS) was found to be involved in the defense against oxidative stress-induced vascular endothelial injury in our previous studies. However, the regulatory signaling pathway underlying this process has not been described. With this chip, we demonstrated that multifactor-induced oxidative stress injury in human aortic endothelial cells (HAECs) has a synergistic effects and upregulates SELENOS expression. Subsequently, SELENOS was found to protect HAECs against multifactor-induced oxidative stress injury by regulating the PKCα/PI3K/Akt/eNOS pathway in the diabetic vascular endothelial microenvironment. Based on these data, our diabetic vascular chip provides a promising tool for studying vascular endothelial function, and SELENOS may be a novel target for prevention and treatment of diabetic macrovascular complications. • We constructed a diabetic vascular microfluidic chip to study the roles and mechanism of SELENOS in endothelial injury. • Multifactor-induced oxidative stress injury in HAECs has a synergistic effects and upregulates SELENOS expression. • SELENOS was found to protect HAECs against multifactor-induced oxidative stress injury via the PKCα/PI3K/Akt/eNOS pathway. [ABSTRACT FROM AUTHOR]