Aim To investigate the effect and mechanism of angiotensin Ⅱ(Ang Ⅱ)on ferroptosis in white adi-pocytes.Methods The 3T3-L1 preadipocytes were differentiated into white adipocytes by inducer stimulation.The experiment was divided into control group,Ang Ⅱ group,Ang Ⅱ+Fer-1(ferroptosis inhibitor)group and Ang Ⅱ+PFT-α(p53 inhibitor)group.Ang Ⅱ was used to treat cells.RT-qPCR and Western blot were used to detect the expression levels of ferroptosis factors and adipokines.JC-1 kit was used to detect mitochondrial membrane potential(MMP)level.Iron ion kit was used to detect intracellular iron content.Glutathione(GSH)kit was used to detect GSH content.Fer-1 and Ang Ⅱ were added to treat cells to detect the the changes of ferroptosis level.The expression of p53 and spermidine/spermine N1-acetyltransferase 1(SAT1)protein was detected.Subsequently,PFT-α and Ang Ⅱ were added to co-treat cells to detect the changes of p53 and SAT1 protein expression,and to observe the effect of inhibiting p53 expression on the expression levels of ferroptosis factors and adipokines.Results 3T3-L1 cells were successfully differentiated into white adipocytes by stimulator-induced differentiation.Ang Ⅱ induced ferroptosis in white adipocytes.RT-qPCR results showed that compared with control group,the mRNA expression of anti-ferroptosis factor glutathione peroxidase 4(GPX4),solute carrier family 7 member 11(SLC7A11)and iron regulatory protein 1(IRP-1)was down-regulated in Ang Ⅱ group,and the mRNA expression of pro-ferroptosis factor acyl-CoA synthetase of long-chain family member 4(ACSL4)was up-regulated.Western blot results showed that compared with control group,the protein expression of SLC7A11 and GPX4 was down-regulated in Ang Ⅱ group,and the protein expression of ACSL4 was up-regulated.Ang Ⅱ treatment increased the content of intracellular iron ions and decreased the levels of GSH and MMP.Compared with Ang Ⅱ group,the mRNA expression of IRP-1 and SLC7A11 was up-regulated in Ang Ⅱ+Fer-1 group.Ang Ⅱ induced changes in the expression profile of adipokines in white adipocytes.Western blot results showed that compared with control group,the protein ex-pression of pro-inflammatory adipokine leptin(LEP),resistin(RETN),interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)was up-regulated in Ang Ⅱ group,and the protein expression of anti-inflammatory adipokine adiponectin(AD-PN)and omentin 1(ITLN1)was down-regulated.In addition,Ang Ⅱ increased the protein expression of p53 and SAT1.Inhibition of p53 expression can improve the level of ferroptosis and adipokine expression in white adipocytes trea-ted with Ang Ⅱ.Western blot results showed that compared with Ang Ⅱ group,the protein expression of p53 and SAT1 was down-regulated in Ang Ⅱ+PFT-α group,the protein expression of SLC7A11 and GPX4 was up-regulated,and the protein expression of ACSL4 was down-regulated.The protein expression of ADPN was up-regulated in Ang Ⅱ+PFT-αgroup,and the protein expression of TNF-α,LEP and RETN was down-regulated.Conclusion Ang Ⅱ induces fer-roptosis in white adipocytes through activating the p53/SAT1 signaling pathway.

Aim To investigate the effect of hydrogen sulfide on macrophage calcification and its underlying mo-lecular mechanisms.Methods Oil red O staining was used to observe intracellular lipid accumulation,and von Kossa staining and atomic absorption spectroscopy were used for morphological and quantitative analysis of calcium deposition and intracellular calcium content in a mononuclear macrophage calcification model.Western blot and RT-PCR were used to detect the mRNA and protein expression of osteopontin(OPN)at different doses and treatment times of hydrogen sulfide.At the same time,Western blot was used to detect the expression changes of early growth response factor 1(EGR1),endo-plasmic reticulum stress-related markers C/EBP homologous protein(CHOP)and glucose-regulated protein 78(GRP78).Reactive oxygen species levels were evaluated by fluorescence probe staining,and the effect of hydrogen sulfide on macro-phage calcification was evaluated by combining von Kossa staining and calcium ion fluorescence probe staining.The mo-lecular mechanisms of hydrogen sulfide affecting macrophage calcification were explored by interfering with EGR1 expression and using endoplasmic reticulum stress inhibitor 4-phenylbutyric acid(4-PBA).Results Compared with oxidized low density lipoprotein(ox-LDL)group,β-glycerophosphate(β-GP)+40 g/L ox-LDL group showed a significant increase in intracellular lipid accumulation,while hydrogen sulfide significantly inhibited macrophage calcification in a con-centration-and time-dependent manner.Compared with the β-GP+ox LDL group,the most significant effect was observed after incubation with 100 μmol/L NaHS for 4 days.The hydrogen sulfide group showed a 66％decrease in intracellular calcium content(P＜0.01),a 71％decrease in intercellular calcium deposition(P＜0.01),and a 50％and 48％decrease in OPN mRNA and protein expression,respectively(P＜0.05).Hydrogen sulfide treatment upregulated the ex-pression of EGR1 by 21％,while downregulating the expression of CHOP and GRP78 by 58％and 59％,respectively(P＜0.01).The endoplasmic reticulum stress inhibitor 4-PBA could downregulate OPN expression by 73％(P＜0.01),while interfering with EGR1 expression completely counteracts the inhibitory effect of hydrogen sulfide on OPN expression and calcium deposition(P＜0.01).Conclusion Hydrogen sulfide significantly inhibits macrophage calcification by upregulating EGR1 expression and suppressing endoplasmic reticulum stress.

Aim To investigate the effect and mechanism of angiotensin Ⅱ(Ang Ⅱ)on ferroptosis in white adi-pocytes.Methods The 3T3-L1 preadipocytes were differentiated into white adipocytes by inducer stimulation.The experiment was divided into control group,Ang Ⅱ group,Ang Ⅱ+Fer-1(ferroptosis inhibitor)group and Ang Ⅱ+PFT-α(p53 inhibitor)group.Ang Ⅱ was used to treat cells.RT-qPCR and Western blot were used to detect the expression levels of ferroptosis factors and adipokines.JC-1 kit was used to detect mitochondrial membrane potential(MMP)level.Iron ion kit was used to detect intracellular iron content.Glutathione(GSH)kit was used to detect GSH content.Fer-1 and Ang Ⅱ were added to treat cells to detect the the changes of ferroptosis level.The expression of p53 and spermidine/spermine N1-acetyltransferase 1(SAT1)protein was detected.Subsequently,PFT-α and Ang Ⅱ were added to co-treat cells to detect the changes of p53 and SAT1 protein expression,and to observe the effect of inhibiting p53 expression on the expression levels of ferroptosis factors and adipokines.Results 3T3-L1 cells were successfully differentiated into white adipocytes by stimulator-induced differentiation.Ang Ⅱ induced ferroptosis in white adipocytes.RT-qPCR results showed that compared with control group,the mRNA expression of anti-ferroptosis factor glutathione peroxidase 4(GPX4),solute carrier family 7 member 11(SLC7A11)and iron regulatory protein 1(IRP-1)was down-regulated in Ang Ⅱ group,and the mRNA expression of pro-ferroptosis factor acyl-CoA synthetase of long-chain family member 4(ACSL4)was up-regulated.Western blot results showed that compared with control group,the protein expression of SLC7A11 and GPX4 was down-regulated in Ang Ⅱ group,and the protein expression of ACSL4 was up-regulated.Ang Ⅱ treatment increased the content of intracellular iron ions and decreased the levels of GSH and MMP.Compared with Ang Ⅱ group,the mRNA expression of IRP-1 and SLC7A11 was up-regulated in Ang Ⅱ+Fer-1 group.Ang Ⅱ induced changes in the expression profile of adipokines in white adipocytes.Western blot results showed that compared with control group,the protein ex-pression of pro-inflammatory adipokine leptin(LEP),resistin(RETN),interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)was up-regulated in Ang Ⅱ group,and the protein expression of anti-inflammatory adipokine adiponectin(AD-PN)and omentin 1(ITLN1)was down-regulated.In addition,Ang Ⅱ increased the protein expression of p53 and SAT1.Inhibition of p53 expression can improve the level of ferroptosis and adipokine expression in white adipocytes trea-ted with Ang Ⅱ.Western blot results showed that compared with Ang Ⅱ group,the protein expression of p53 and SAT1 was down-regulated in Ang Ⅱ+PFT-α group,the protein expression of SLC7A11 and GPX4 was up-regulated,and the protein expression of ACSL4 was down-regulated.The protein expression of ADPN was up-regulated in Ang Ⅱ+PFT-αgroup,and the protein expression of TNF-α,LEP and RETN was down-regulated.Conclusion Ang Ⅱ induces fer-roptosis in white adipocytes through activating the p53/SAT1 signaling pathway.

Aim To investigate the effect of hydrogen sulfide on macrophage calcification and its underlying mo-lecular mechanisms.Methods Oil red O staining was used to observe intracellular lipid accumulation,and von Kossa staining and atomic absorption spectroscopy were used for morphological and quantitative analysis of calcium deposition and intracellular calcium content in a mononuclear macrophage calcification model.Western blot and RT-PCR were used to detect the mRNA and protein expression of osteopontin(OPN)at different doses and treatment times of hydrogen sulfide.At the same time,Western blot was used to detect the expression changes of early growth response factor 1(EGR1),endo-plasmic reticulum stress-related markers C/EBP homologous protein(CHOP)and glucose-regulated protein 78(GRP78).Reactive oxygen species levels were evaluated by fluorescence probe staining,and the effect of hydrogen sulfide on macro-phage calcification was evaluated by combining von Kossa staining and calcium ion fluorescence probe staining.The mo-lecular mechanisms of hydrogen sulfide affecting macrophage calcification were explored by interfering with EGR1 expression and using endoplasmic reticulum stress inhibitor 4-phenylbutyric acid(4-PBA).Results Compared with oxidized low density lipoprotein(ox-LDL)group,β-glycerophosphate(β-GP)+40 g/L ox-LDL group showed a significant increase in intracellular lipid accumulation,while hydrogen sulfide significantly inhibited macrophage calcification in a con-centration-and time-dependent manner.Compared with the β-GP+ox LDL group,the most significant effect was observed after incubation with 100 μmol/L NaHS for 4 days.The hydrogen sulfide group showed a 66％decrease in intracellular calcium content(P＜0.01),a 71％decrease in intercellular calcium deposition(P＜0.01),and a 50％and 48％decrease in OPN mRNA and protein expression,respectively(P＜0.05).Hydrogen sulfide treatment upregulated the ex-pression of EGR1 by 21％,while downregulating the expression of CHOP and GRP78 by 58％and 59％,respectively(P＜0.01).The endoplasmic reticulum stress inhibitor 4-PBA could downregulate OPN expression by 73％(P＜0.01),while interfering with EGR1 expression completely counteracts the inhibitory effect of hydrogen sulfide on OPN expression and calcium deposition(P＜0.01).Conclusion Hydrogen sulfide significantly inhibits macrophage calcification by upregulating EGR1 expression and suppressing endoplasmic reticulum stress.

Aim To investigate the role and regulatory mechanism of CREB regulated transcription coactivator 2(CRTC2)in cardiomyocyte hypertrophy.Methods A pathological cardiomyocyte hypertrophy model was established in C57BL/6 mice by intraperitoneal injection of isoproterenol(ISO),the expression of CRTC2 in cardiac tissue was detec-ted by Western blot.The CRTC2 knockout mice model was constructed,the cardiac function of mice was detected by small animal echocardiography,the collagen fiber content in mice cardiac tissue was detected by Masson staining,the car-diomyocyte hypertrophy related proteins:skeletal muscle α1-actin(ACTA1)and brain natriuretic peptide(BNP),as well as ferroptosis related proteins:acyl-CoA synthetase long chain family member 4(ACSL4),solute carrier family 7 member 11(SLC7A11)and glutathione peroxidase 4(GPX4)in mice cardiac tissue were detected by Western blot,the iron ion content in mice cardiac tissue was detected by iron ion kit,to evaluate the correlation between CRTC2 and cardiomyocyte hypertrophy and ferroptosis.H9c2 cells were induced by ISO to construct an in vitro model of cardiomyocyte hypertrophy,the protein expressions of CRTC2,ACTA1,BNP,ACSL4,SLC7A11 and GPX4 were detected after intervention with fer-roptosis inhibitor ferrostatin-1(Fer-1).H9c2 cells with CRTC2 overexpression induced by ISO were used to construct an in vitro model of cardiomyocyte hypertrophy,the related indicators of cardiomyocyte hypertrophy and ferroptosis were detec-ted to explore the mechanism of CRTC2 in cardiomyocyte hypertrophy.Results Compared with the control group,the expression of CRTC2 protein in the cardiac tissue of ISO induced cardiomyocyte hypertrophy mice was increased(P＜0.05).Compared with wild-type mice,CRTC2-/-mice showed worsened cardiac function,manifested as increased left ventricular end-diastolic diameter(LVEDD),left ventricular end-systolic diameter(LVESD),left ventricular posterior wall thickness(LVPWT),heart weight/tibia length(HW/TL)and heart weight/body weight(HW/BW),decreased short axis shortening(FS)and ejection fraction(EF),increased collagen fiber content in cardiac tissue,upregulated ex-pression of cardiomyocyte hypertrophy-related proteins ACTA1 and BNP,increased mRNA and protein expression of ferrop-tosis-related protein ACSL4,decreased mRNA and protein expression of SLC7A11 and GPX4,and elevated iron ion content in cardiac tissue(P＜0.05 or P＜0.01).In vitro experiments showed that compared with ISO group,the ISO+Fer-1 group had no significant change in CRTC2 protein expression(P＞0.05),the expression of ACTA1 and BNP protein decreased,the surface area of cardiomyocyte reduced,the expression of ACSL4 protein decreased,and the expression of SLC7A11 and GPX4 proteins increased(P＜0.05 or P＜0.01).Compared with the ISO group,the LV-CRTC2+ISO group showed a decrease in surface area of cardiomyocytes(P＜0.01),a decrease in ACTA1,BNP and ACSL4 protein ex-pression,an increase in SLC7A11 and GPX4 protein expression,and a decrease in ROS and iron ion content(P＜0.05 or P＜0.01).Conclusion CRTC2 alleviates cardiomyocyte hypertrophy and protect cardiac function by suppressing fer-roptosis in cardiomyocytes.

Objective:To understand the graduation destination of newly graduated medical master's students in China and analyze their employment status.Methods:A questionnaire survey was conducted on 15 942 medical master's students who graduated in 2023. Descriptive analysis, χ2 test, and Kruskal-Wallis rank-sum test were used to understand the current situation and differences in the graduation destinations, employment units, job positions, and starting salaries of different types of medical master's graduates. Results:The employment rate of medical master's graduates was 58.21% (9 280/15 942). In terms of graduation destinations, male graduates, professional degree holders, graduates from non-"Double First-Class" universities, and nursing majors had a high proportion of confirmed employment units. Male graduates, academic degree holders, graduates from "Double First-Class" universities, and basic medical science majors had a high proportion pursuing further studies domestically. In terms of employment, the highest proportion of medical master's graduates worked in hospitals (84.92%, 6 495/7 648) and the lowest proportion worked in primary-level medical and healthcare institutions (1.02%, 78/7 648). The majority (78.07%, 5 971/7 648) held professional technical positions. Starting salaries were relatively low and ranged between 3 001 and 5 000 yuan/month, accounting for 30.99% (2 370/7 648).Conclusions:The employment rate of medical master's graduates is low, with concentrated employment units and job positions, and there is a lack of talents in primary medical institutions. Colleges and universities and education management departments should adopt policy-driven approaches to support key demographic groups and encourage employment in primary healthcare. Training programs should be timely adjusted in response to market demands and focus on cultivating the comprehensive quality and job competence of medical master's graduates. Additionally, student-centered approaches should be used to strengthen the employment guidance and career planning services.

Objective:To understand the graduation destination of newly graduated medical master's students in China and analyze their employment status.Methods:A questionnaire survey was conducted on 15 942 medical master's students who graduated in 2023. Descriptive analysis, χ2 test, and Kruskal-Wallis rank-sum test were used to understand the current situation and differences in the graduation destinations, employment units, job positions, and starting salaries of different types of medical master's graduates. Results:The employment rate of medical master's graduates was 58.21% (9 280/15 942). In terms of graduation destinations, male graduates, professional degree holders, graduates from non-"Double First-Class" universities, and nursing majors had a high proportion of confirmed employment units. Male graduates, academic degree holders, graduates from "Double First-Class" universities, and basic medical science majors had a high proportion pursuing further studies domestically. In terms of employment, the highest proportion of medical master's graduates worked in hospitals (84.92%, 6 495/7 648) and the lowest proportion worked in primary-level medical and healthcare institutions (1.02%, 78/7 648). The majority (78.07%, 5 971/7 648) held professional technical positions. Starting salaries were relatively low and ranged between 3 001 and 5 000 yuan/month, accounting for 30.99% (2 370/7 648).Conclusions:The employment rate of medical master's graduates is low, with concentrated employment units and job positions, and there is a lack of talents in primary medical institutions. Colleges and universities and education management departments should adopt policy-driven approaches to support key demographic groups and encourage employment in primary healthcare. Training programs should be timely adjusted in response to market demands and focus on cultivating the comprehensive quality and job competence of medical master's graduates. Additionally, student-centered approaches should be used to strengthen the employment guidance and career planning services.

Aim To investigate the role and regulatory mechanism of CREB regulated transcription coactivator 2(CRTC2)in cardiomyocyte hypertrophy.Methods A pathological cardiomyocyte hypertrophy model was established in C57BL/6 mice by intraperitoneal injection of isoproterenol(ISO),the expression of CRTC2 in cardiac tissue was detec-ted by Western blot.The CRTC2 knockout mice model was constructed,the cardiac function of mice was detected by small animal echocardiography,the collagen fiber content in mice cardiac tissue was detected by Masson staining,the car-diomyocyte hypertrophy related proteins:skeletal muscle α1-actin(ACTA1)and brain natriuretic peptide(BNP),as well as ferroptosis related proteins:acyl-CoA synthetase long chain family member 4(ACSL4),solute carrier family 7 member 11(SLC7A11)and glutathione peroxidase 4(GPX4)in mice cardiac tissue were detected by Western blot,the iron ion content in mice cardiac tissue was detected by iron ion kit,to evaluate the correlation between CRTC2 and cardiomyocyte hypertrophy and ferroptosis.H9c2 cells were induced by ISO to construct an in vitro model of cardiomyocyte hypertrophy,the protein expressions of CRTC2,ACTA1,BNP,ACSL4,SLC7A11 and GPX4 were detected after intervention with fer-roptosis inhibitor ferrostatin-1(Fer-1).H9c2 cells with CRTC2 overexpression induced by ISO were used to construct an in vitro model of cardiomyocyte hypertrophy,the related indicators of cardiomyocyte hypertrophy and ferroptosis were detec-ted to explore the mechanism of CRTC2 in cardiomyocyte hypertrophy.Results Compared with the control group,the expression of CRTC2 protein in the cardiac tissue of ISO induced cardiomyocyte hypertrophy mice was increased(P＜0.05).Compared with wild-type mice,CRTC2-/-mice showed worsened cardiac function,manifested as increased left ventricular end-diastolic diameter(LVEDD),left ventricular end-systolic diameter(LVESD),left ventricular posterior wall thickness(LVPWT),heart weight/tibia length(HW/TL)and heart weight/body weight(HW/BW),decreased short axis shortening(FS)and ejection fraction(EF),increased collagen fiber content in cardiac tissue,upregulated ex-pression of cardiomyocyte hypertrophy-related proteins ACTA1 and BNP,increased mRNA and protein expression of ferrop-tosis-related protein ACSL4,decreased mRNA and protein expression of SLC7A11 and GPX4,and elevated iron ion content in cardiac tissue(P＜0.05 or P＜0.01).In vitro experiments showed that compared with ISO group,the ISO+Fer-1 group had no significant change in CRTC2 protein expression(P＞0.05),the expression of ACTA1 and BNP protein decreased,the surface area of cardiomyocyte reduced,the expression of ACSL4 protein decreased,and the expression of SLC7A11 and GPX4 proteins increased(P＜0.05 or P＜0.01).Compared with the ISO group,the LV-CRTC2+ISO group showed a decrease in surface area of cardiomyocytes(P＜0.01),a decrease in ACTA1,BNP and ACSL4 protein ex-pression,an increase in SLC7A11 and GPX4 protein expression,and a decrease in ROS and iron ion content(P＜0.05 or P＜0.01).Conclusion CRTC2 alleviates cardiomyocyte hypertrophy and protect cardiac function by suppressing fer-roptosis in cardiomyocytes.

Objective:To explore the changes in entero-insular axis function and its role in mice with severe burns.Methods:This study was an experimental study. Ninety C57BL/6J male mice aged 8-10 weeks were divided into sham injury group and burn group (with 45 mice in each group) according to the random number table. A full-thickness scald (hereinafter referred to as burn) wound of 30% of the total body surface area was created on the back of mice in burn group, and the mice in sham injury group were simulated to cause a sham injury. Twenty-four hours after injury, the fasting blood glucose was measured ( n=12), followed by intraperitoneal glucose tolerance test and oral glucose tolerance test; the curve of blood glucose concentration changes over time was plotted, and the area under the curve was calculated ( n=6); the blood was taken from the heart before intraperitoneal injection or gavage of glucose solution and at 30, 60, and 120 minutes after intraperitoneal injection or gavage of glucose solution for measuring the plasma insulin and glucagon like peptide-1 (GLP-1) levels using enzyme-linked immunosorbent assay (ELISA), with a sample number of 3; the ileal tissue was taken from 3 mice in each group for detecting the GLP-1 expression and apoptosis levels of intestinal L cells by immunofluorescence staining and TdT-mediated dUTP nick-end labeling staining; the pancreatic islets were collected from 6 mice in each group for glucose-stimulated insulin secretion experiments. After incubation with low glucose (2.8 mmol/L glucose) and high glucose (16.7 mmol/L glucose), the supernatant was taken and the insulin level was detected using ELISA. Thirty-six C57BL/6J male mice aged 8-10 weeks were divided into sham injury group, burn group, and burn+exendin-4 (Ex-4) group (with 12 mice in each group) according to the random number table. The mice in sham injury group and burn group were subjected to the same corresponding treatment as before. The mice in burn+Ex-4 group were injured in the same way as the burn group mice followed by treatment with GLP-1 receptor agonist Ex-4. Twenty-four hours after injury, mouse pancreatic islets were collected, the protein expressions of heavy-chain binding protein (BIP), protein kinase R-like endoplasmic reticulum kinase (PERK), phosphorylated PERK (p-PERK), eukaryotic translation initiation factor 2α (eIF2α), phosphorylated eIF2α (p-eIF2α), and CCAAT/enhancer-binding protein homologous protein (CHOP) were detected using Western blotting, and the p-PERK/PERK and p-eIF2α/eIF2α ratios were calculated ( n=3), the apoptosis rate of pancreatic islet cells was detected using flow cytometry ( n=3), the glucose stimulated insulin secretion experiment was conducted as before to detect insulin levels in the supernatant ( n=6). Results:Twenty-four hours after injury, the fasting blood glucose of mice in burn group was (7.3±1.0) mmol/L, which was significantly higher than (5.1±0.6) mmol/L in sham injury group ( t=6.36, P<0.05). Twenty-four hours after injury, in the intraperitoneal glucose tolerance test and oral glucose tolerance test, the areas under the curve of blood glucose concentration changes over time of mice in burn group were significantly larger than those in sham injury group (with t values of 4.32 and 6.03, respectively, P<0.05); compared with those in sham injury group, the plasma insulin levels of mice before intraperitoneal injection of glucose solution and the plasma GLP-1 levels of mice before intraperitoneal injection or gavage of glucose solution in burn group were significantly decreased ( P<0.05), and the plasma levels of insulin of mice at 30, 60, and 120 minutes after intraperitoneal injection or gavage of glucose solution, as well as the plasma levels of GLP-1 of mice at 30 and 60 minutes after gavage of glucose solution were significantly decreased in burn group ( P<0.05). Twenty-four hours after injury, compared with those in sham injury group, the GLP-1 expression level of intestinal L cells of mice in burn group was significantly decreased ( t=7.74, P<0.05), and the apoptosis level was significantly increased ( t=14.28, P<0.05). Twenty-four hours after injury, the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn group was (8.5±0.4) ng/mg, which was significantly lower than (15.7±0.3) ng/mg in sham injury group ( t=18.68, P<0.05). Twenty-four hours after injury, compared with those in sham injury group, the protein expression levels of BIP, p-PERK/PERK, p-eIF2α/eIF2α, and CHOP in the pancreatic islets of mice in burn group were significantly increased ( P<0.05); compared with those in burn group, the protein expression levels of BIP, p-PERK/PERK, p-eIF2α/eIF2α, and CHOP in the pancreatic islets of mice in burn+Ex-4 group were significantly decreased ( P<0.05). Twenty-four hours after injury, the apoptosis rate of pancreatic islet cells of mice in burn group was (32.0±3.0)%, which was significantly higher than (10.3±2.5)% in sham injury group ( P<0.05); the apoptosis rate of pancreatic islet cells of mice in burn+Ex-4 group was (20.0±3.6)%, which was significantly lower than that in burn group ( P<0.05). Twenty-four hours after injury, the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn group was significantly lower than that in sham injury group ( P<0.05), while the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn+Ex-4 group was significantly higher than that in burn group ( P<0.05). Conclusions:After severe burns, the mice display dysfunction of the entero-insular axis, increased apoptosis of intestinal L cells, decreased synthesis and secretion of GLP-1, endoplasmic reticulum stress and increased apoptosis in pancreatic islet cells and a decrease in glucose-stimulated insulin secretion. The GLP-1 receptor agonist Ex-4 can protect the function of pancreatic islet cells of mice with severe burns, reducing the apoptosis level of pancreatic islet cells and promoting insulin secretion possibly via the alleviation of endoplasmic reticulum stress.

AIM:To investigate the potential impact of mitoNEET[mitochondrial protein containing Asn-Glu-Glu-Thr(NEET)sequence]on mitochondrial metabolism in brown adipocytes,and to elucidate its underlying mecha-nism.METHODS:An in vitro model of primary mouse brown adipocytes was established.Western blot were utilized to detect relevant proteins,and iron ion and ATP content was measured using kits.Mitochondrial membrane potential and re-active oxygen species(ROS)were assessed by fluorescence microscopy and flow cytometry.RESULTS:The expression of the ferroptosis-related protein ACSL4 increased by 1.13 times in ferroptosis inducer erastin treatment group,whereas the expression of SLC7A11 and GPX4 decreased by 27.33%and 25.33%,respectively,compared with control group(P<0.05).The expression of Nrf1,PGC-1α,MFN2 and UCP1 proteins,related to mitochondrial energy metabolism,de-creased by 20.98%,15.17%,15.03%and 34.22%,respectively(P<0.05).Additionally,the mitoNEET protein con-tent was significantly reduced by 42.14%(P<0.05).The iron ion content in erastin group was substantially increased by 1.80 times compared with control group.However,a notable decrease in ATP content of 14.95%was seen(P<0.05).The results obtained from fluorescence microscopy and flow cytometry demonstrated a significant decrease in the mitochon-drial membrane potential of brown adipocytes in erastin group,with reductions of 52.18%and 61.31%(P<0.05),re-spectively.A substantial increase in mitochondrial ROS content of 80.97%was seen(P<0.05).Western blot analysis of overexpressed stable strains revealed a significant elevation in mitoNEET levels in brown adipocytes following lentivirus transfection,exhibiting an increase of 11.19 times(P<0.05),thus confirming successful transfection.The LV-mitoNEET group exhibited a significant decrease of 37.95%in the expression of ferroptosis-related protein ACSL4 in brown adipose cells compared with control group.Additionally,there was a notable increase of 77.82%and 66.3%in the expression of SLC7A11 and GPX4,respectively(P<0.05).Up-regulation was observed in the expression of MFN2(79.06%),PGC-1α(72.89%),Nrf1(40.14%),and UCP1(31.68%)(P<0.05).The test results demonstrated that the LV-mitoNEET group experienced a reduction of 43.5%in iron ion content compared with control group while exhibiting an increase of 33.5%in ATP content(P<0.05).The results obtained from fluorescence microscopy and flow cytometry demonstrated that mitoNEET overexpression led to a significant increase in the mitochondrial membrane potential of erastin-induced brown adipocytes,with increments of 17.61%and 96.05%,respectively.Additionally,mitoNEET overexpression effec-tively reduced the production of mitochondrial ROS by 24.48%(P<0.05).CONCLUSION:Our findings suggest that mitoNEET overexpression can effectively inhibit the disruption of mitochondrial energy metabolism caused by ferroptosis-induced death of brown adipocytes.