Palmitate Contributes to Insulin Resistance through Downregulation of the Src-Mediated Phosphorylation of Akt in C2C12 Myotubes

The mechanisms of free fatty acid (FFA)-induced peripheral insulin resistance remain elusive. This study aimed to investigate the effect of palmitate, a saturated fatty acid, on glucose metabolism in C2C12 myotubes, and to explore the underlying mechanisms. In it, palmitate decreased insulin-stimulated glucose uptake and consumption in a dose-dependent manner, and it reduced the insulin-stimulated phosphorylation of Akt at Thr308 and Ser473, but had no effect on the protein expression of PI3K-p85 or the activity of PI3K. Additionally, it inhibited the insulin-stimulated phosphorylation of Src at Tyr416, causing a reduction in the Src-mediated phosphorylation of Akt. Inhibition of Src by PP2 resulted in decreases in insulin-stimulated glucose uptake and phosphorylation of Src at Tyr416 and Akt at Thr308 and Ser473. The findings indicate that palmitate contributes to insulin resistance by inhibiting the Src-mediated phosphorylation of Akt in C2C12 myotubes, and this provides insight into the molecular mechanisms of FFA-induced insulin resistance.     

Renal improvement by zinc in diabetic mice is associated with glucose metabolism signaling mediated by metallothionein and Akt,but not Akt2

Human epidemiological and animal studies have shown the beneficial effect of zinc supplementation on mitigating diabetic nephropathy. However, the mechanism by which zinc protects the kidney from diabetes remains unknown. Here we demonstrate the therapeutic effects of zinc on diabetes-induced renal pathological and functional changes. These abnormalities were found in both transgenic OVE26 and Akt2-KO diabetic mouse models, accompanied by significant changes in glucose-metabolism-related regulators. The changes included significantly decreased phosphorylation of Akt and GSK-3β, increased phosphorylation of renal glycogen synthase, decreased expression of hexokinase II and PGC-1α, and increased expression of the Akt negative regulators PTEN, PTP1B, and TRB3. All of these were significantly prevented by zinc treatment for 3 months. Furthermore, zinc-stimulated changes in glucose metabolism mediated by Akt were actually found to be metallothionein dependent, but not Akt2 dependent. These results suggest that the therapeutic effects of zinc in diabetic nephropathy are mediated, in part, by the preservation of glucose-metabolism-related pathways via the prevention of diabetes-induced upregulation of Akt negative regulators. Given that zinc deficiency is very common in diabetics, this finding implies that regularly monitoring zinc levels in diabetic patients, as well as supplementing if low, is important in mitigating the development of diabetic nephropathy.     

Overexpression of STAMP2 suppresses atherosclerosis and stabilizes plaques in diabetic mice

Our research aims to evaluate the function of the STAMP2 gene, an important trigger in insulin resistance (IR), and explore its role in macrophage apoptosis in diabetic atherosclerotic vulnerable plaques. The characteristics of diabetic mice were measured by serial metabolite and pathology tests. The level of STAMP2 was measured by RT‐PCR and Western blot. The plaque area, lipid and collagen content of brachiocephalic artery plaques were measured by histopathological analyses, and the macrophage apoptosis was measured by TUNEL. Correlation of STAMP2/Akt signaling pathway and macrophage apoptosis was validated by Ad‐STAMP2 transfection and STAMP2 siRNA inhibition. The diabetic mice showed typical features of IR, hyperglycaemia. Overexpression of STAMP2 ameliorated IR and decreased serum glucose level. In brachiocephalic lesions, lipid content, macrophage quantity and the vulnerability index were significantly decreased by overexpression of STAMP2. Moreover, the numbers of apoptotic cells and macrophages in lesions were both significantly decreased. In vitro, both mRNA and protein expressions of STAMP2 were increased under high glucose treatment. P‐Akt was highly expressed and caspase‐3 was decreased after overexpression of STAMP2. However, expression of p‐Akt protein was decreased and caspase‐3 was increased when STAMP2 was inhibited by siRNA. STAMP2 overexpression could exert a protective effect on diabetic atherosclerosis by reducing IR and diminishing macrophage apoptosis.     

A high-fat diet catalyzes progression to hyperglycemia in mice with selective impairment of insulin action in Glut4-expressing tissues

Insulin resistance impairs postprandial glucose uptake through glucose transporter type 4 (GLUT4) and is the primary defect preceding type 2 diabetes. We previously generated an insulin-resistant mouse model with human GLUT4 promoter-driven insulin receptor knockout (GIRKO) in the muscle, adipose, and neuronal subpopulations. However, the rate of diabetes in GIRKO mice remained low prior to 6 months of age on normal chow diet (NCD), suggesting that additional factors/mechanisms are responsible for adverse metabolic effects driving the ultimate progression of overt diabetes. In this study, we characterized the metabolic phenotypes of the adult GIRKO mice acutely switched to high-fat diet (HFD) feeding in order to identify additional metabolic challenges required for disease progression. Distinct from other diet-induced obesity (DIO) and genetic models (e.g., db/db mice), GIRKO mice remained leaner on HFD feeding, but developed other cardinal features of insulin resistance syndrome. GIRKO mice rapidly developed hyperglycemia despite compensatory increases in β-cell mass and hyperinsulinemia. Furthermore, GIRKO mice also had impaired oral glucose tolerance and a limited glucose-lowering benefit from exendin-4, suggesting that the blunted incretin effect contributed to hyperglycemia. Secondly, GIRKO mice manifested severe dyslipidemia while on HFD due to elevated hepatic lipid secretion, serum triglyceride concentration, and lipid droplet accumulation in hepatocytes. Thirdly, GIRKO mice on HFD had increased inflammatory cues in the gut, which were associated with the HFD-induced microbiome alterations and increased serum lipopolysaccharide (LPS). In conclusion, our studies identified important gene/diet interactions contributing to diabetes progression, which might be leveraged to develop more efficacious therapies.     

Protection against diabetic cardiomyopathy is achieved using a combination of sulforaphane and zinc in type 1 diabetic OVE26 mice

Sulforaphane (SFN) can effectively induce nuclear factor E2–related factor 2 (Nrf2), and zinc (Zn) can effectively induce metallothionein (MT), both of which have been shown to protect against diabetic cardiomyopathy (DCM). However, it is unclear whether combined treatment with SFN and Zn offers better cardiac protection than either one alone. Here, we treated 5‐week‐old OVE mice that spontaneously develop type 1 diabetes with SFN and/or Zn for 18 weeks. Cardiac dysfunction, by echocardiography, and pathological alterations and remodelling, shown by cardiac hypertrophy, fibrosis, inflammation and oxidative damage, examined by histopathology, Western blotting and real‐time PCR, were observed in OVE mice. All these dysfunction and pathological abnormalities seen in OVE mice were attenuated in OVE mice with treatment of either SFN, Zn or SFN/Zn, and the combined treatment with SFN/Zn was better than single treatments at ameliorating DCM. In addition, combined SFN and Zn treatment increased Nrf2 function and MT expression in the heart of OVE mice to a greater extent than SFN or Zn alone. This indicates that the dual activation of Nrf2 and MT by combined treatment with SFN and Zn may be more effective than monotherapy at preventing the development of DCM via complementary, additive mechanisms.     

Pollen Typhae total flavone improves insulin resistance in high-fat diet and low-dose streptozotocin-induced type 2 diabetic rats

Pollen Typhae total flavone (PTF), the extract from Pollen Typhae, is reported to enhance glucose uptake in C2C12 myotubes in vitro, but the convincing evidence is lacking in vivo. In this study, PTF ameliorated insulin resistance and dyslipidemia, but failed to significantly increase body weight in type 2 diabetic rats induced by high-fat diet and low-dose streptozotocin.     

1型糖尿病小鼠肝脏的口服葡萄糖代谢及差异表达基因

目的：观察口服葡萄糖在1型糖尿病小鼠肝脏的代谢,比较1型糖尿病小鼠与正常小鼠口服葡萄糖后肝组织基因表达的差异。方法：链脲霉素（STZ）诱导C57雄性小鼠1型糖尿病模型为实验组（n=8）,正常C57雄性小鼠为对照组（n=8）。每组随机取2只,按50ml／kg给予4％葡萄糖生理盐水溶液灌胃,2h取肝组织检测基因表达谱（Mouse Genome 430 2．0Array）。每组另6只．同样剂量给予含14C标记葡萄糖。结果：糖尿病小鼠口服14C标记葡萄糖2h后,肝组织同位素水平是正常对照组的4倍。以正常对照组为参比,共有舛条基因的表达变化差异在2倍以上,其中上调基因61个,下调基因33个。根据功能基因组分析,11条差异表达基因与脂代谢、胆固醇代谢相关,其中7条上调基因与脂、胆固醇合成相关,1条下调基因与脂肪酸分解相关。结论：SIZ诱导的1型糖尿病小鼠口服葡糖后2h,肝脏脂、胆固醇合成相关基因表达增高。     

Ebselen enhances insulin sensitivity and decreases oxidative stress by inhibiting SHIP2 and protects from inflammation in diabetic mice

Ebselen, a multifunctional organoselenium compound, has been recognized as a potential treatment for diabetes-related disorders. However, the underlying mechanisms whereby ebselen regulates metabolic pathways remain elusive. We discovered that ebselen inhibits lipid phosphatase SHIP2 (Src homology 2 domain-containing inositol-5-phosphatase 2), an emerging drug target to ameliorate insulin resistance in diabetes. We found that ebselen directly binds to and inhibits the catalytic activity of the recombinant SHIP2 phosphatase domain and SHIP2 in cultured cells, the skeletal muscle and liver of the diabetic db/db mice, and the liver of the SHIP2 overexpressing (SHIP2-Tg) mice. Ebselen increased insulin-induced Akt phosphorylation in cultured myotubes, enhanced insulin sensitivity and protected liver tissue from lipid peroxidation and inflammation in the db/db mice, and improved glucose tolerance more efficiently than metformin in the SHIP2-Tg mice. SHIP2 overexpression abrogated the ability of ebselen to induce glucose uptake and reduce ROS production in myotubes and blunted the effect of ebselen to inhibit SHIP2 in the skeletal muscle of the SHIP2-Tg mice. Our data reveal ebselen as a potent SHIP2 inhibitor and demonstrate that the ability of ebselen to ameliorate insulin resistance and act as an antioxidant is at least in part mediated by the reduction of SHIP2 activity.     

In vivo therapeutic exploring for Mori folium extract against type 2 diabetes mellitus in rats

Background: The study was aimed to investigate the potential therapeutic effect of Mori folium aqueous extracts (MFAE) on type 2 diabetes mellitus (T2DM) in vivo.Methods and results: A rat model of T2DM was established with the combination of high sugar and high-fat diet (HSFD) and streptozotocin (STZ). The T2DM rats were administrated with low (2 g.kg⁻¹) and high (5 g.kg⁻¹) doses of MFAE for 60 consecutive days. The biochemical indices of glucose metabolism disorders, insulin resistance and oxidative stress were observed. The results indicated that MFAE significantly promoted the synthesis of hepatic glycogen, reduced the levels of fasting blood glucose and fasting blood insulin, and improved the insulin sensitivity index (ISI). MFAE administration also remarkably increased the levels of superoxide dismutase (SOD) and reduced the levels of malondialdehyde (MDA).Conclusion: MFAE showed a therapeutic effect on T2DM with the bioative effect of improve glucose metabolism disorders, decrease insulin resistance, and ameliorate the antioxidative ability.     

Autophagic adaptations in diabetic cardiomyopathy differ between type 1 and type 2 diabetes

Little is known about the association between autophagy and diabetic cardiomyopathy. Also unknown are possible distinguishing features of cardiac autophagy in type 1 and type 2 diabetes. In hearts from streptozotocin-induced type 1 diabetic mice, diastolic function was impaired, though autophagic activity was significantly increased, as evidenced by increases in microtubule-associated protein 1 light chain 3/LC3 and LC3-II/-I ratios, SQSTM1/p62 (sequestosome 1) and CTSD (cathepsin D), and by the abundance of autophagic vacuoles and lysosomes detected electron-microscopically. AMP-activated protein kinase (AMPK) was activated and ATP content was reduced in type 1 diabetic hearts. Treatment with chloroquine, an autophagy inhibitor, worsened cardiac performance in type 1 diabetes. In addition, hearts from db/db type 2 diabetic model mice exhibited poorer diastolic function than control hearts from db/+ mice. However, levels of LC3-II, SQSTM1 and phosphorylated MTOR (mechanistic target of rapamycin) were increased, but CTSD was decreased and very few lysosomes were detected ultrastructurally, despite the abundance of autophagic vacuoles. AMPK activity was suppressed and ATP content was reduced in type 2 diabetic hearts. These findings suggest the autophagic process is suppressed at the final digestion step in type 2 diabetic hearts. Resveratrol, an autophagy enhancer, mitigated diastolic dysfunction, while chloroquine had the opposite effects in type 2 diabetic hearts. Autophagy in the heart is enhanced in type 1 diabetes, but is suppressed in type 2 diabetes. This difference provides important insight into the pathophysiology of diabetic cardiomyopathy, which is essential for the development of new treatment strategies.     

AdipoRon对2型糖尿病小鼠肾脏损伤的干预作用

目的：研究脂联素受体激动剂（AdipoRon）对2型糖尿病小鼠肾脏损伤的干预作用。方法：将40只SPF级雄性C57/BL6小鼠随机分为正常对照组（n=10）和实验组（n=30）：实验组给予高糖、高脂饲料喂养,联合腹腔注射小剂量链脲佐菌素（STZ）建立2型糖尿病（T2DM）小鼠模型,再随机分为3组（n=10）：模型对照（DM）组、低剂量AdipoRon治疗（DM+L）组及高剂量AdipoRon治疗（DM+H）组。检测血清中葡萄糖含量的变化;采用酶联免疫法检测小鼠血清中胰岛素受体（INSR）、胰岛素受体底物-1（IRS-1）以及肿瘤坏死因子-α（TNF-α）的蛋白质含量;HE染色镜下观察肾组织形态学变化;实时荧光定量PCR法检测肾组织胰岛素促进因子-1（PDX-1）和胰岛素（insulin）mRNA的表达;Western blot检测肾组织内磷酸化胰岛素受体底物-1（p-IRS-1）蛋白质;ELISA试剂盒检测小鼠血胰岛素含量。结果：病理学检查表明,AdipoRon可减轻2型糖尿病所致小鼠肾脏损伤。与DM组小鼠比较,DM+H组和DM+L组小鼠血糖、TNF-α水平均显著降低（P<0.05）,INSR、IRS-1和p-IRS-1表达显著上升,PDX-1和insulin mRNA表达显著上升（P<0.05,P<0.01）。结论：给予AdipoRon治疗的小鼠血糖和血清TNF-α水平显著降低,INSR,IRS-1和p-IRS-1蛋白质含量,PDX-1和insulin mRNA表达均显著上升,表明AdipoRon对2型糖尿病小鼠肾脏损伤有一定的干预作用。     

Chronological approach of diet-induced alterations in muscle mitochondrial functions in rats

Objective: Mitochondrial dysfunction might predispose individuals to develop insulin resistance. Our objective was to determine whether mitochondrial dysfunction or insulin resistance was the primary event during high‐fat (HF) diet. Research Methods and Procedures: Rats were fed an HF diet for 0, 3, 6, 9, 14, 20, or 40 days and compared with control. Soleus and tibialis muscle mitochondrial activity were assessed using permeabilized fiber technique. Insulin [area under the curve for insulin (AUC_I)] and glucose [area under the curve for glucose (AUC_G)] responses to intraperitoneal glucose tolerance test as well as fasting plasma non‐esterified fatty acids (NEFAs), triglyceride, and glycerol concentrations were determined. Results: AUC_I and AUC_G were altered from Day 6 (p < 0.01 vs. Day 0). In soleus, oxidative phosphorylation (OXPHOS) activity was transiently enhanced by 26% after 14 days of HF diet (p < 0.05 vs. Day 0) conjointly with 62% increase in NEFA concentration (p < 0.05 vs. Day 0). This was associated with normalized AUC_G at Day 14 and with a decline of plasma NEFA concentration together with stabilization of intra‐abdominal adiposity at Day 20. Prolongation of HF diet again caused an increase in plasma NEFA concentration, intra‐abdominal adiposity, AUC_I, and AUC_G. At Day 40, significant decrease in OXPHOS activity was observed in soleus. Discussion: Mitochondria first adapt to overfeeding in oxidative muscle limiting excess fat deposition. This potentially contributes to maintain glucose homeostasis. Persistent overfeeding causes insulin resistance and results in a slow decline in oxidative muscle OXPHOS activity. This shows that the involvement of mitochondria in the predisposition to insulin resistance is mainly due to an inability to face prolonged excess fat delivery.     

Functionalized gadofullerene ameliorates impaired glycolipid metabolism in type 2 diabetic mice

The soaring global prevalence of diabetes makes it urgent to explore new drugs with high efficacy and safety. Nanomaterial-derived bioactive agents are emerging as one of the most promising candidates for biomedical application. In the present study, we investigated the anti-diabetic effects of a functionalized gadofullerene (GF) using obese db/db and non-obese mouse model of type 2 diabete mellitus (MKR) mouse type 2 diabetes mellitus (T2DM) models. In both mouse models, the diabetic phenotypes, including hyperglycemia, impaired glucose tolerance, and insulin sensitivity, were ameliorated after two or four weeks of intraperitoneal administration of GF. GF lowered blood glucose levels in a dose-dependent manner. Importantly, the restored blood glucose levels could persist ten days after withdrawal of GF treatment. The hepatic AKT/GSK3β/FoxO1 pathway is shown to be the main target of GF for rebalancing gluconeogenesis and glycogen synthesis in vivo and in vitro. Furthermore, GF treatment significantly reduced weight gain of db/db mice with reduced hepatic fat storage by the inhibition of de novo lipogenesis through mTOR/S6K/SREBP1 pathway. Our data provide compelling evidence to support the promising application of GF for the treatment of T2DM.     

Nicorandil alleviates apoptosis in diabetic cardiomyopathy through PI3K/Akt pathway

Nicorandil exerts myocardial protection through its antihypoxia and antioxidant effects. Here, we investigated whether it plays an anti‐apoptotic role in diabetic cardiomyopathy. Sprague‐Dawley rats were fed with high‐fat diet; then single intraperitoneal injection of streptozotocin was performed. Rats with fasting blood glucose (FBG) higher than 11.1 mmol/L were selected as models. Eight weeks after the models were built, rats were treated with nicorandil (7.5 mg/kg day and 15 mg/kg day respectively) for 4 weeks. H9c2 cardiomyocytes were treated with nicorandil and then stimulated with high glucose (33.3 mmol/L). TUNEL assay and level of bcl‐2, bax and caspase‐3 were measured. 5‐HD was used to inhibit nicorandil. Also, PI3K inhibitor (Miltefosine) and mTOR inhibitor (rapamycin) were used to inhibit PI3K/Akt pathway. The results revealed that nicorandil (both 7.5 mg/kg day and 15mg/kg day) treatment can increase the level of NO in the serum and eNOS in the heart of diabetic rats compared with the untreated diabetic group. Nicorandil can also improve relieve cardiac dysfunction and reduce the level of apoptosis. In vitro experiments, nicorandil (100 µmol) can attenuate the level of apoptosis stimulated by high glucose significantly in H9C2 cardiomyocyte compared with the untreated group. The effect of nicorandil on apoptosis was blocked by 5‐HD, and it was accompanied with inhibition of the phosphorylation of PI3K, Akt, eNOS, and mTOR. After inhibition of PI3K/Akt pathway, the protective effect of nicorandil is restrained. These results verified that as a NO donor, nicorandil can also inhibit apoptosis in diabetic cardiomyopathy which is mediated by PI3K/Akt pathway.     

有氧运动对2型糖尿病大鼠骨骼肌ERK1/2活性的影响

目的：观察有氧运动对2型糖尿病大鼠骨骼肌细胞外信号调节激酶（ERK1/2）活性的影响,探讨有氧运动对2型糖尿病的预防和调控机制。方法：将75只SD大鼠随机分为正常对照组（CON）、糖尿病对照1组（DC1）、糖尿病运动1组（DE1）、糖尿病对照2组（DC2）、糖尿病运动2组（DE2）5组（n=15）。正常对照组用普通饲料喂养,糖尿病组用高脂高糖配方饲料喂养。经过8周高脂高糖喂养后,糖尿病2组大鼠腹腔内注射链脲佐菌素（STZ）,诱发2型糖尿病;糖尿病运动1组游泳的最后1周初和糖尿病对照1组同时注射STZ,注射剂量为35 mg/kg,3 d后尾部取血测血糖≥ 16.7 mmol/L为造模成功。运动干预8周后,测定大鼠血清胰岛素、骨骼肌中ERK1/2蛋白表达等指标。结果：①与正常对照组比较,糖尿病各对照组血液中总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白（LDL-C）、游离脂肪酸（FFA）显著升高（P<0.05,P<0.01）,空腹血糖（FBG）、胰岛素（FIN）含量和胰岛素抵抗指数（HOMA-IR）显著升高（P<0.01）,ERK1/2磷酸化的蛋白表达显著下降（P<0.05）,糖尿病对照2组ERK1/2蛋白含量显著下降（P<0.05）;②8周游泳运动后,与糖尿病对照组比较,糖尿病运动组血液中TC、TG、FFA、LDL-C显著下降（P<0.05）,FBG、FIN、HOMA-IR显著下降（P<0.05,P<0.01）,ERK1/2磷酸化蛋白表达显著升高（P<0.05）。结论：长时间有氧运动,增加了骨骼肌ERK1/2磷酸化水平,改善了2型糖尿病大鼠胰岛素抵抗的状况,降低血糖。这可能是改善糖代谢紊乱,提高胰岛素敏感性的机制之一。     

Metabolic flexibility is conserved in diabetic myotubes

The purpose of this study was to test the hypothesis that metabolic inflexibility is an intrinsic defect. Glucose and lipid oxidation were studied in human myotubes established from healthy lean and obese subjects and patients with type 2 diabetes (T2D). In lean myotubes, glucose oxidation is raised by increasing glucose concentrations (0-20 mmol/l) and acute insulin stimulation (P < 0.05), whereas it is inhibited by palmitate (PA). PA oxidation is raised by increasing PA concentrations (0-0.6 mmol/l), whereas 1.0 mmol/l PA inhibits its own oxidation (P < 0.05). Furthermore, PA oxidation is increased by acute insulin stimulation (P < 0.05) and inhibited by glucose. Even 0.05 mM PA and 2.5 mM glucose significantly reduce glucose and PA oxidation (P < 0.05), respectively. Glucose and PA oxidation are insulin-sensitive in myotubes established from lean (46% and 17% glucose and PA oxidation, respectively; P < 0.05 vs. basal), obese (31% and 14%; P < 0.05), and T2D (17% and 8%; P < 0.05) subjects. PA supplementation reduces both basal and insulin-stimulated glucose oxidation by 33-44% (P < 0.05), and myotubes are still insulin-sensitive in all three groups (P < 0.05). Therefore, the metabolic inflexibility described in obese and diabetic patients is not an intrinsic defect; rather, it is based on an extramuscular mechanism (i.e., the inability to vary extracellular fatty acid concentrations during insulin stimulation). Thus, skeletal muscles are metabolic-flexible per se.     

Acute insulin secretion as a predictor of weight gain in healthy humans

Objective: We sought to determine the role of the acute insulin secretory response to glucose (AIRg) in predicting weight gain in normoglycemic persons with no family history of diabetes, who are at low risk for development of disease. Research Methods and Procedures: One hundred five individuals (64 men and 41 women) who underwent measures of weight and AIRg and insulin sensitivity index (S_I) by intravenous glucose tolerance test between 1963 and 1983 were surveyed again for weight between 1994 and 1999, with a mean follow‐up of 26 ± 4 years. Results: Mean change in weight was 8 ± 10 kg. Annualized weight change was calculated as change in kilograms divided by change in year and averaged 0.27 ± 0.04 kg/yr. Dividing the cohort by either median AIRg or median S_I demonstrated no association of either AIRg or S_I with total or annualized weight gain. Subgroup analysis by ideal body weight or gender did not alter the association. Furthermore, no association between AIRg and weight gain rate was seen within insulin‐sensitive or ‐resistant subgroups, although younger age at entry was associated with greater rates of weight gain. Discussion: Our data suggest that neither AIRg nor S_I plays a role in predicting weight gain in normoglycemic individuals with no family history of diabetes.     

过表达磷脂酶D3影响成肌细胞中Akt磷酸化水平

磷脂酶D(PLD)催化卵磷脂(Phosphatidylc holine,PC)水解产生胆碱(Choline)和磷脂酸(Phosphatidic acid,PA),其代谢产物参与调控细胞内许多生理和生化过程。在过表达磷脂酶D3(PLD3)的成肌细胞(C2C12细胞)中,研究了PLD3对胰岛素刺激后Akt通路激活的影响。研究结果表明,PLD3过表达细胞的Akt磷酸化水平比对照组低,并且不受胰岛素浓度变化的调控。虽然PLD3过表达细胞中Akt磷酸化水平随胰岛素刺激时间的延长而有所增加,但磷酸化总水平比对照组低。磷脂酶D抑制剂丁-1醇能够抑制对照组胰岛素刺激下Akt磷酸化,却不能抑制PLD3过表达细胞的Akt磷酸化,并且PLD3过表达细胞Akt磷酸化水平比对照组高6倍。用磷脂酸(PA)做刺激时,对照组的Akt磷酸化明显增加,而PLD3过表达细胞株的Akt磷酸化没有显著变化;用PA和胰岛素同时刺激时,PLD3过表达株和对照组的Akt磷酸化均比PA单独刺激时降低。这说明PLD3的过表达抑制成肌细胞内胰岛素信号的传导。