LRP16 gene protects mouse insulinoma MIN6 cells against fatty acid-induced apoptosis through Akt/FoxO1 signaling

Background  Pancreatic b cells are susceptible to fatty acid-induced apoptosis. The 17b-estradiol (E2) protects pancreatic b cells from apoptosis, mediated by the estrogen receptor-a (ERa). The mRNA level and promoter activity of leukemia-related protein (LRP) 16 were significantly increased by E2 in ER-a and LRP16 was a co-activator of ER-a. The aim of the study was to assess the effects of LRP16 on fatty acid-induced apoptosis in MIN6 cells.

Methods  Cells with over-expressing LRP16 were obtained by lipidosome transfection. Insulin content and glucose-stimulated insulin secretion (GSIS) were examined by radioimmunoassay. Western blotting was applied to detect protein expression. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and flow cytometry. The forkhead boxO1 (FoxO1) subcellular localization was determined by immunocytochemical analysis.

Results  MIN6-LRP16 cells with overexpression of LRP16 were successfully established, and protein expression of LRP16 was 2.29-fold of that of control cells (MIN6-3.1, P <0.05). Insulin content and GSIS in MIN6-LRP16 were substantially increased compared with those in control cells. When cells were stimulated with glucose, increased phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and serine-threonine kinase (Akt) were observed in MIN6-LRP16. When cells were under palmitate pressure, the TUNEL-positive rate in MIN6-LRP16 was (17.0±0.5)%, while it in MIN6-3.1 was (22.0±0.4)%. In palmitate-treated cells, attenuated Akt phosphorylation was observed, but the attenuation in Akt activity was partially restored in MIN6-LRP16 cells. Meanwhile, nuclear localization of FoxO1 in MIN6-LRP16 was apparently reduced compared with that in control cells.

Conclusions  LRP16 regulated insulin content and GSIS in MIN6 cells by ERK1/2 and Akt activated way. Meanwhile, LRP16 overexpression protected MIN6 cells from fatty acid-induced apoptosis by partially restoring Akt phosphorylation and inhibiting FoxO1 nuclear redistribution. Therefore, LRP16 played important roles not only in insulin content and GSIS but also in the antilipotoxic effect mediated by Akt /FoxO1 signaling.

     

Mechanism by which statins influence insulin signaling pathway

Recent studies have shown that statins can influence insulin resistance （IR） in animal models and inhumans.1.2 However, the mechanism by which statins influence the insulin signaling pathway （ISP） remains obscure. It has been proposed that the pleiotropic effects of statins might be involved in regulation of IR.The phosphatidylinositol 3-kinase （PI3K）-Akt/protein kinase B （PKB） pathway is the main ISE Insulin binding to insulin receptor initiates PI3K-Akt pathway by phosphorylates tyrosine residue of IR substrate proteins （IRSs） including IRS-1 and IRS-2. Activation of the PI3K leads to the accumulation of phosphatidylinositol 3,4,5-triphosphate （PIP3）. PIP3 activates serine/ threonine kinase （Akt）. Glucose transporter-4 （GLUT-4） translocates to plasma membrane from cytosol by serine phosphorylation of Akt and directly regulates glucose metabolism in liver, muscle and adipose tissue （Figure 1）. However, an overall mechanism by which statins influence ISP remained obscure.     

Genistein reverses free fatty acid-induced insulin resistance in HepG2 hepatocytes through targeting JNK

This study investigated the effects and molecular mechanisms of genistein in improving insulin resistance induced by free fatty acids (FFAs) in HepG2 hepatocytes. A model of insulin resistance in HepG2 cells was established by adding palmitic acid (0.5 mmol/L) to the culture medium and the cells were treated by genistein. Glucose consumption of HepG2 cells was determined by glucose oxidase method. The levels of c-jun N-terminal kinase (JNK) phosphorylation, insulin receptor substrate-1 (IRS-1) Ser307 phosphorylation, JNK, IRS-1, phosphatidylinositol-3-kinase p85 (PI-3K p85) and glucose transporter 1 (GLUT1) proteins were detected by Western blotting. The results showed that after the treatment with palmitic acid for 24 h, the insulin-stimulated glucose transport in HepG2 cells was inhibited, and the glucose consumption was substantially reduced. Meanwhile, the expressions of IRS-1, PI-3K p85 protein and GLUT1 were obviously reduced, while the levels of JNK phosphorylation and IRS-1 Ser307 phosphorylation and the expression of JNK protein were significantly increased, as compared with cells of normal control. However, the aforementioned indices, which indicated the existence of insulin resistance, were reversed by genistein at 1-4 μmol/L in a dose-dependent manner. It was concluded that insulin resistance induced by FFAs in HepG2 hepatocytes could be improved by genistein. Genistein might reverse FFAs-induced insulin resistance in HepG2 cells by targeting JNK.     

交泰丸通过骨骼肌磷脂酰肌醇(-3)激酶通路提高糖尿病大鼠胰岛素信号强度

Objective: To investigate the effect of Jiaotai Pill (交泰丸, JTP) at different constitutional proportions on insulin signaling through phosphatidylinositol 3-kinase (PI3K) pathway in the skeletal muscle of diabetic rats. Methods: The rat model of type 2 diabetes mellitus (T2DM) was established by intravenous injection of a small dose of streptozotoein plus high fat diet feeding. JTP at the same dosage of cinnamon and the increasing dosage of Coptis chinensis was administered to diabetic rats for nine weeks respectively. Plasma glucose and insulin levels were assayed. The expressions of proteins were determined by Western blot method. Results: All the three formulations of JTP decreased plasma glucose and fasting insulin levels as well as increased the protein expressions of insulin receptor β (InsRβ) subunit, insulin receptor substrate-1 (IRS-1), PI3K p85 subunit and glucose transporter 4 (GLUT4) in skeletal muscle. Meanwhile, JTP increased the tyrosine phosphorylation of InsRβ subunit and IRS-1, and reduced the serine phosphorylation of IRS-1 in skeletal muscle. Interestingly, the effect of JTP on improving insulin sensitivity was not dose-dependent. In contrast, JTP containing the least amount of Coptis chinensis exhibited the best effect. Conclusion: JTP at different constitutional proportions attenuates the development of diabetes in a rat model of T2DM. The mechanism might be associated with enhancing insulin signaling through PI3K pathway in the skeletal muscle.     

Chronic Hyperinsulinism Induced Down-regulation of Insulin Post-Recentor Signaling Transduction in Hep G2 Cells

Summary: To study the regulatory effect of acute and chronic insulin treatment on insulin post-re-ceptor signaling transduction pathway in a human hepatoma cell line (Hep G2), Hep G2 cells wereincubated in the presence or absence of insulin with different concentrations in serum free mediafor 16 h and then stimulated with 100 nmol/L insulin for 1 min. Protein levels of insulin receptorβ-subunit (IRβ), insulin receptor substrate-1 (IRS-1) and p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase) were determined in total cell lysates by Western-immunoblot. Phosphorylat-ed proteins IRβ, IRS-1 and interaction of PI 3-kinase with IRS-1 were determined by immunopre-cipitation. Results showed that 1-min insulin stimulation rapidly induced tyrosine phosphorylationof IRβ and IRS-l, which in turn, resulting in association of PI 3-kinase with IRS-1. 1-100 nmol/L chronic insulin treatment induced a dose-dependent decrease in the protein level of IRβ and aslight decrease in the protein level of IRS-1. There wass more marked reduction in the phospho-rylation of IRβ, IRS-1, reaching a nadir of 22 % (P＜0. 01) and 15 % (P＜0. 01) of control lev-els, respectively, after 16 h treatment with 100 nmol/L insulin. The association between IRS-1and PI 3-kinase was decreased by 66 % (P＜0. 01). There was no significant change in PI 3-ki-nase protein levels. These data suggest that chronic insulin treatment can induce alterations ofIRβ, IRS-1 and PI 3-kinase three early steps in insulin action, which contributes significantly toinsulin resistance, and may account for desensitization of insulin action.     

MAGI3 Suppresses Glioma Cell Proliferation via Upregulation of PTEN Expression

Objective To investigate the role and molecular mechanism of membrane-associated guanylate kinase inverted 3 (MAGI3) in glioma cell proliferation.
Methods The expression levels of MAGI3 and PTEN were assessed in glioma samples by Western blotting. MAGI3 was stably transfected into C6 glioma cells to obtain C6-MAGI3 cells. Then, the proliferation, the expression levels of MAGI3 and PTEN, and Akt phosphorylation were evaluated in C6 and C6-MAGI3 cells. Xenograft tumor models were established by subcutaneous injection of C6 and C6-MAGI3 cells into nude mice, and the growth rates of xenografts in the mice were compared. The potential role of MAGI3 expression in PI3K/Akt signaling activation was further investigated by examining the correlation between MAGI3 expression and the expression of PI3K/Akt signaling downstream target genes in a glioma dataset using gene set enrichment analysis (GSEA).
Results Expression levels of MAGI3 and PTEN were significantly downregulated in gliomas. Overexpression of MAGI3 in the glioma C6 cell line upregulated PTEN protein expression, inhibited the phosphorylation of Akt, and suppressed cell proliferation. MAGI3 overexpression also inhibited the growth of C6 glioma tumor xenografts in nude mice. Analysis based on the GEO database confirmed the negative correlation between activation of PI3K/Akt pathway and MAGI3 mRNA levels in human glioma samples.
Conclusion The loss of MAGI3 expression in glioma may enhance the proliferation of glioma cells via downregulation of PTEN expression, leading to the activation of the PI3K/Akt pathway. MAGI3 is a potential glioma suppressor.     

Association of β3 Adrenergic Receptor and Peroxisome Proliferator-activated Receptor Gamma 2 Polymorphisms With Insulin Sensitivity： A Twin Study

Objective To study the effect of β3 adrenergic receptor(β3AR) Trp64Arg and peroxisome proliferator activated receptor gamma 2(PPARγ2) Pro12Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment(HOMA). PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method,identity by state(IBS) was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg,Trp64Arg,and Arg64Arg were 72.3%,23.8%,and 3.9%,respectively,while the genotype frequencies of Pro12Pro,Pro12Ala,and Ala12Ala were 89.9%,9.6%,and 0.5%,respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio(WHR),blood glucose(GLU),and insulin(INS),homeostasis model assessment insulin resistance index(HOMA-IR) of the twin pairs sharing 2 alleles of IBS were greater than those sharing 0-1 allele of IBS,and HOMA-IR had statistic significance. For PPARγ2 Pro12Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index(BMI),WHR,percent of body fat(PBF) and GLU,but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Conclusions β3AR Trp64Arg and PPARγ2 Pro12Ala polymorphisms might be associated with insulin resistance and obesity,and there might be slight synergistic effects between this two gene loci,and further studies are necessary to confirm this finding.     

Antihyperglycemic and antihyperlipidemic action of cinnamaldehyde in C57blks/j Db/db mice

OBJECTIVE:To investigate the effects of cinnamaldehyde(CA),an active and major compound in cinnamon,on glucose metabolism and insulin resistance in C57BLKS/J db/db mice.METHODS:Sixteen male C57BLKS db/db mice were randomly divided into control and CA treatment groups.CA was given(20 mg.kg-1.day-1,p.o.) for 4 weeks.Pure water was given to control and db/+ mice.Subsequently,the levels of fasting blood glucose(FBG),fasting serum insulin,triglyeride,cholesterol,low-density lipoprotein-cholesterol(LDL-C),high-density lipoprotein-cholesterol(HDL-C),and free fatty acids(FFA),as well as the mRNA content of adiponectin and tumor necrosis factor(TNF)-α in adipose tissue,glucose transporter type 4(GLUT-4) in skeletal muscle,and protein expressions of Akt,phospho-Akt(Thr308),AMPKα,phospho-AMPKα(Thr172) in skeletal muscle were measured.RESULTS:1) CA decreased serum levels of FBG and insulin as well as body weight in db/db mice;2) CA increased serum HDL-C levels;3) CA significantly decreased the mRNA expression of TNF-α in adipose tissue and upregulated mRNA expression of GLUT-4 in skeletal muscle;4) protein expression of p-Akt was increased in CA-treated mice,but Akt,AMPKα and p-AMPKα showed no change.CONCLUSION:CA has antihyperglycemic and antihyperlipidemic actions in db/db mice and could be useful in the treatment of type-2 diabetes.     

可溶性环氧化合物水解酶抑制剂对脂肪细胞脂质代谢及分泌功能的影响

目的 观察可溶性环氧化合物水解酶抑制剂(tAUCB)对脂肪细胞摄取与降解氧化型低密度脂蛋白(ox-LDL)及分泌功能的影响.方法 分别用1、10、50和100μmol/L tAUCB干预已刺激分化成熟的脂肪细胞24 h,0 μmol/L tAUCB干预作为空白对照组,分别在加人tAUCB前1 h加入过氧化物酶体增殖物激活受体γ(PPARγ)拮抗剂(GW9662)5μmol/L.采用125Ⅰ放射配基法测定脂肪细胞对ox-LDL的摄取与降解;实时定量-PCR和Western印迹分别测定脂肪细胞PPARγ和CD36mRNA及蛋白的表达;ELISA检测脂肪细胞培养液中脂联素(ADP)、肿瘤坏死因子α(TNF-α)水平.结果 tAUCB呈剂量依赖性地促进ox-LDL的摄取与降解,tAUCB(10、50、100 μmol/L)干预,其摄取ox-LDL分别为(35.6±1.1)ng/mg、(39.8±1.6)ng/mg、(42.6±1.4)ng/mg;降解量为(2879±54)ng/mg、(3082±56)ng/mg、(3226±68)ng/mg,显著高于空白对照组[(28.9±1.2)ng/mg、(2791±54),ng/mg均P＜0.05];加入GW9662后,其ox-LDL摄取量分别下降为(30.6±1.3)ng/mg、(31.1±1.7)ng/mg、(32.1±1.8)ng/mg.降解量下降为(2788±53)ng/mg,(2824±70)ng/mg,(2874±70)ng/mg,与单独加入相应浓度tAUCB组相比差异有统计学意义(P＜0.05).tAUCB呈剂量依赖性地增加脂肪细胞CD36和PPARγmRNA及蛋白的表达,并且降低脂肪细胞分泌TNF-α,增加抗炎因子ADP的浓度,而GW9662明显抑制tAUCB的上述作用.结论 tAUCB可通过上调PPARγ促进脂肪细胞CD36的表达,从而增加细胞对ox-LDL的摄取与降解,同时可能通过上调PPARγ的表达而调节ADP,TNF-α等脂肪炎症因子的分泌.

Abstract：

Objective To observe the effects of soluble epoxide hydrolase inhibitors-tAUCB on the uptake and degradation of ox-LDL in adipocytes. Methods 3T3-L1 preadipocytes were induced into differentiation and maturation. After a 24-hour starvation, the cells were stimulated with 1O0 ng/ml LPS and then tAUCB at various concentrations(0-100 μmol/L)were added for 24 h, or preincubated with the PPARγ (peroxisome proliferators activated receptor gamma) antagonist GW9662 (5 μmol/L). And the 0 μ mol/LtAUCB-treated group was taken as the blank control group. Then the uptake and degradation of ox-LDL in cells were measured by radioligand assay. The mRNA expressions of PPARγ and CD36 were detected by real-time PCR ( polymerase chain reaction). And the intracellular levels of protein expression of PPARγand CD36 were detected by Western blot. While ADP and TNF-α in supernatant were detected by ELISA. Results tAUCB could dose-dependently increase the uptake and degradation of ox-LDL in adipocytes. When stimulated with 10, 50, 1O0 μmol/L tAUCB, the uptake levels of ox-LDL were (35. 6 ±1.1 ) ng/mg, (39. 8 ± 1.6) ng/mg, (42. 6 ± 1.4) ng/mg cell protein and the degradation levels of ox-LDL (2879 ±54)ng/mg, (3082 ± 56)ng/mg, (3226 ± 68 )ng/mg cell protein. And they were significantly higher than those of the control group ( 28.9 ± 1.2) ng/mg、 (2791 ± 54) ng/mg respectively ( all P ＜ 0.05 ).However, after preincubation of GW9662, the uptake of ox-LDL were decreased to (30.6 ± 1.3) ng/mg,(31. 1 ± 1.7)ng/mg, (32. 1 ± 1.8 ) ng/mg cell protein whereas the degradation of ox-LDL decreased to (2788 ± 53 ) ng/mg, ( 2824 ± 70 ) ng/mg, ( 2874 ± 70) ng/mg cell protein. And the difference was statistically significant when it was compared with the corresponding tAUCB-treated group. With the rising concentration of tAUCB, tAUCB could dose-dependently increase the mRNA and protein expression of CD36 and PPARγ. tAUCB could dose-dependently decrease the levels of TNF-α and increase the levels of ADP in adipocytes. GW9662 could significantly inhibit those effects of tAUCB and reduce the uptake and degradation of ox-LDL and the expression of PPARγand CD36 in adipocytes. Conclusion tAUCB can upregulate the PPARγ expression in adipocytes and promote the uptake and degradation of ox-LDL in adipocytes via PPARγ-CD36 pathway. Meanwhile, the levels of ADP and TNF-α may be mediated through the activation of PPARγ.     

3T3L1脂肪细胞对大鼠胰岛β细胞功能障碍的影响

Objective To investigate the integrated effects of adipocytes on rat beta-cells, differentiated 3T3L1 adipocytes and rat islet cells co-culture system was established. Methods There were two groups; control group ( SD rat islet cells) and co-culture group (islet cells and 3T3L1 adipocytes co-culture system). Islet cells were obtained for determination of (1) insulin secretion and insulin content; (2) mRNA expressions of GLUT2, GCK and Kir6. 2; (3) protein expressions of IR-β, IRS-1 and their tyrosine phosphorylation leveL Results (1) At low glucose, insulin secretion of co-culture group increased compared with that of control group (0.79±0.35) ng·h-1 · ml-1 islet vs (0.38±0.09 ) ng · h-1 · ml-1 · islet, P = 0. 028 . At high glucose, insulin secretion of those two groups was almost at the same level (P =0.760). Compared with control group (2. 84 ±0.92) , stimulation index (SI, insulin release at high glucose/ low glucose) of co-culture system decreased to (1. 57 ±0. 61, P =0.04). And the insulin content of the both groups was almost at the same level (P=0.102). (2) The mRNA of GCK, GLUT2 and Kir6. 2 in co-culture group downregulated to (0. 27 ±0. 11, P = 0. 01) , (0. 34 ±0. 24, P = 0. 009) and (0.41 ± 0. 09, P = 0. 003) compared with control group (mRNA = 1). ( 3) The protein levels of IR-β, IRS-1 and their tyrosine phosphorylation decreased in co-culture system. Conclusions 3T3L1 adipocytes are involved in beta-cell dysfunction, which may facilitate the development of type 2 diabetes. The effects may be mediated by multiple pathways, which include downregulation of GSIS related gene expressions and suppression of islet cell insulin signaling.     

3T3L1脂肪细胞对大鼠胰岛β细胞功能障碍的影响

Objective To investigate the integrated effects of adipocytes on rat beta-cells, differentiated 3T3L1 adipocytes and rat islet cells co-culture system was established. Methods There were two groups; control group ( SD rat islet cells) and co-culture group (islet cells and 3T3L1 adipocytes co-culture system). Islet cells were obtained for determination of (1) insulin secretion and insulin content; (2) mRNA expressions of GLUT2, GCK and Kir6. 2; (3) protein expressions of IR-β, IRS-1 and their tyrosine phosphorylation leveL Results (1) At low glucose, insulin secretion of co-culture group increased compared with that of control group (0.79±0.35) ng·h-1 · ml-1 islet vs (0.38±0.09 ) ng · h-1 · ml-1 · islet, P = 0. 028 . At high glucose, insulin secretion of those two groups was almost at the same level (P =0.760). Compared with control group (2. 84 ±0.92) , stimulation index (SI, insulin release at high glucose/ low glucose) of co-culture system decreased to (1. 57 ±0. 61, P =0.04). And the insulin content of the both groups was almost at the same level (P=0.102). (2) The mRNA of GCK, GLUT2 and Kir6. 2 in co-culture group downregulated to (0. 27 ±0. 11, P = 0. 01) , (0. 34 ±0. 24, P = 0. 009) and (0.41 ± 0. 09, P = 0. 003) compared with control group (mRNA = 1). ( 3) The protein levels of IR-β, IRS-1 and their tyrosine phosphorylation decreased in co-culture system. Conclusions 3T3L1 adipocytes are involved in beta-cell dysfunction, which may facilitate the development of type 2 diabetes. The effects may be mediated by multiple pathways, which include downregulation of GSIS related gene expressions and suppression of islet cell insulin signaling.     

Decrease in myostatin by ladder-climbing training is associated with insulin resistance in diet-induced obese rats

Background Suppression of myostatin （MSTN） has been associated with skeletal muscle atrophy and insulin resistance （IR）.However,few studies link MSTN suppression by ladder-climbing training （LCT） and IR.Therefore,we intended to identify the correlation with IR between LCT and to analyze the signaling pathways through which MSTN suppression by LCT regulates IR.Methods The rats were randomly assigned to two types of diet：normal pellet diet （NPD,n=8） and high-fat diet （HFD,n=16）.After 8 weeks,the HFD rats were randomly re-assigned to two groups （n=8 for each group）：HFD sedentary （HFD-S） and high-fat diet ladder-climbing training （HFD-LCT）.HFD-LCT rats were assigned to LCT for 8 weeks.Western blotting,immunohistochemistry and enzyme assays were used to measure expression levels and activities of MSTN,GLUT4,PI3K,Akt and Akt-activated targets （mTOR,FoxO1 and GSK-3β）.Results The LCT significantly improved IR and whole-body insulin sensitivity in HDF-fed rats.MSTN protein levels decreased in matching serum （42％,P=0.007） and muscle samples （25％,P=0.035） and its receptor mRNA expression also decreased （16％,P=0.041） from obese rats after LCT.But the mRNA expression of insulin receptor had no obvious changes in LCT group compared with NPD and HFD-S groups （P=0.074）.The ladder-climbing training significantly enhanced PI3K activity （1.7-fold,P=0.024） and Akt phosphorylation （83.3％,P=0.022） in HFD-fed rats,significantly increased GLUT4 protein expression （84.5％,P=-0.036）,enhanced phosphorylation of mTOR （4.8-fold,P ＜0.001） and inhibited phosphorylation of FoxO1 （57.7％,P=0.020）,but did not affect the phosphorylation of GSK-3β.Conclusions The LCT significantly reduced IR in diet-induced obese rats.MSTN may play an important role in regulating IR and fat accumulation by LCT via PI3K/Akt/mTOR and PI3K/Akt/FoxO1 signaling pathway in HFD-fed rats.     

多囊卵巢综合征合并胰岛素抵抗患者子宫内膜胰岛素受体底物1、2蛋白的表达及酪氨酸磷酸化

目的 研究多囊卵巢综合征(polycystie ovarian syndrome,PCOS)患者子宫内膜胰岛素受体底物(insulin re-ceptor substrate IRS)1 和 2 蛋白的表达及酪氨酸磷酸化的程度.探讨 PCOS 子宫内膜胰岛素抵抗的分子机制.方法 于月经周期第 1 天刮取 PCOS 合并胰岛素抵抗患者(PCOS组,15 例)和正常妇女(对照组,10 例)子宫内膜,行病理切片观察及免疫组化染色,计算机图像分析系统分析子宫内膜 IRS-1 和 IRS-2 蛋白的表达及酪氨酸磷酸化程度.结果 ①PCOS 组和对照组 IRS-1 蛋白表达的灰度值分别为(121.94±16.00)和(55.35±0.98),IRS-2 蛋白分别为(169.35±13.00)和(111.65±8.02),两组比较差异有显著性意义(P<0.01,P<0.05),PCOS 组子宫内膜 IRS-1 和 IRS-2 蛋白的表达明显降低;②PCOS 组子宫内膜 IRS 酪氨酸磷酸化的程度明显低于对照组,其灰度值分别为(141.98±22.50)、(102.72±9.78),两组比较差异有显著性意义(P<0.05).结论 PCOS 合并胰岛素抵抗患者子宫内膜组织的 IRS-1 和IRS-2 蛋白表达及酪氨酸磷酸化的程度异常所导致的受体后信号传导障碍,可能是发生胰岛素抵抗机制之一.     

Study on insulin resistance and genetic polymorphisms in essential hypertension patients of two different kinds of TCM constitution

Objective:To investigate the relationship of insulin resistance and the polymorphisms of insulin receptor-related genes in essential hypertension patients of two different kinds of TCM constitution.Methods:Oral glucose tolerance test (OGTT) and insulin release test (InRT) were conducted in 217 essential hypertensive patients of either sluggish meticulous (SM) constitution (139 cases) or prosperous impetuous (PI) constitution (78 cases),and the polymorphism of three genes, including insulin-like growth factor-1 receptor (IGF-1R),insulin receptor substrate-1 (IRS-1) and 2 (IRS-2) genes were detected.Results:(1) OGTT,InRT and insulin resistance index (Homa-IR) were higher and insulin sensitive index (ISI) was lower in the patients of SM constitution than those in patients of PI constitution.(2) Significant difference of ISI and Homa-IR was shown in patients of both constitutions with genotype G of the 3 genes.Conclusion:Decrease of insulin sensitivity and increase of insulin resistance are more obvious in hypertensive patients with genotype G of the 3 genes of SM constitution than in those of PI constitution.Therefore,the difference in constitution might be one of the genetic characteristics for insulin resistance in hypertensive patients.     

Reversal of Multidrug Resistance and Inhibition of Phosphorylation of AKT in Human Ovarian Cancer Cell Line by Wild-type PTEN Gene

The reversing effect of wild-type PTEN gene on resistance of C13K cells to cisplatin and its inhibitory effect on the phosphorylation of protein kinase B (AKT) were studied. The expression of PTEN mRNA and protein in OV2008 cells and C13K cells were semi-quantitatively detected by using RT-PCR and Western blotting. Recombinant eukaryotic expression plasmid containing human wild-type PTEN gene was transfected into C13K cells by lipofectamine2000. The expression of PTEN mRNA was monitored by RT-PCR and the expression of PTEN, Akt, p-Akt protein were ana- lyzed by Western blotting in PTEN-transfected and non-transfected C13K cells. Proliferation and chemosensitivity of cells to DDP were measured by MTT, and cell apoptosis was detected by flow cytometry after treatment with cisplatin. The expression of PTEN mRNA and protein in OV2008 cells were significantly higher than those in C13K cells. After transfection with PTEN gene for 48 h, the expression of PTEN mRNA and protein in C13K cells were 2.04±0.10, 0.94±0.04 respectively and the expression of p-Akt protein ( 0.94±0.07) was lower than those in control groups (1.68±0.14, 1.66±0.10) (P< 0.05). The IC50 of DDP to C13K cells transfected with PTEN (7.2±0.3 μmol/L) was obviously lower than those of empty-vector transfected cells and non-transfected cells (12.7±0.4 μmol/l, 13.0±0.3 μmol/L) (P<0.05). The apopototis ratio of wild-type PTEN-transfected, empty vector transfected and non-transfected C13K cells were (41.65±0.87)%, (18.61±0.70)% and (15.28 ±0.80)% respectively, and the difference was statistically significant (P<0.05). PTEN gene plays an important role in ovarian cancer multidrug resistance. Transfection of PTEN could increase the ex- pression of PTEN and restore drug sensitivity to cisplatin in human ovarian cancer cell line C13K with multidrug-resistance by decreasing the expression of p-Akt.