Regulation Of Insulin Sensitivity Research Articles

Effects of Chronic Administration of Pioglitazone on Learning and Memory in Rat Model of Streptozotocin-induced Alzheimer’s Disease

Background: Alzheimer’s Disease (AD) is a chronic neurodegenerative disease characterized by abnormal protein accumulation, synaptic dysfunction, and cognitive impairment. Peroxisome Proliferator-Activated Receptor-γ (PPARγ) play a crucial role in regulating insulin sensitivity and may serve as potential therapeutic targets for AD. Pioglitazone (PIOG), as a PPARγ agonist, reduces β-amyloid and tau proteins, and inhibits neuroinflammation. Objective: This study aims to evaluate the effects of PIOG chronic administration on learning and memory in rat model of Streptozotocin (STZ)-induced AD Methods: Forty-two male Wistar rats were divided into two groups: A. Normal rats divided into three subgroups of Control, Dimethyl Sulfoxide (DMSO), and PIOG; and B. AD rats divided into four subgroups of Vehicle, STZ, STZ+DMSO and STZ+PIOG. The last two AD subgroups received 0.2 mL DMSO and PIOG (10 mg/kg per day) for 21 days. For induction of AD, STZ (3 mg/kg, 10 μl per injection site) were administered into lateral ventricles. All rates were trained under the Morris water maze task. Findings: PIOG impaired the spatial learning and memory in normal rats. Intracerebroventricular injection of STZ significantly increased escape latency and swimming time to find the hidden platform compared to the control group (P<0.05). The amnesic effect of STZ was prevented by PIOG administration such that the escape latency and swimming time to find the hidden platform in the STZ+PIOG group were significantly lower than in the STZ+DMSO group (P<0.05). Conversely, the percentage of time spent and distance swimming in the target quadrant in the probe test in the STZ+ PIOG group rats were significantly higher than those in the STZ + DMSO group. Conclusion: PIOG administration impaired spatial learning and memory in normal rats, but improved learning and memory in rats with STZ-induced AD. It can be useful for treatment of cognitive impairment in AD patients.

Tankyrase inhibition augments neuronal insulin sensitivity and glucose uptake via AMPK-AS160 mediated pathway

Tankyrase, a member of poly (ADP-ribose) polymerase (PARP) family, regulates various cellular pathways including wnt signaling, telomere maintenance and mitosis, has become a prime target for the development of cancer therapeutics. Inhibition of tankyrase, which leads to its increased cellular accumulation, reveal the role of tankyrase in the regulation of Glucose transporter type 4 (GLUT4) translocation and glucose homeostasis in peripheral insulin responsive tissues. While in adipocytes inhibition of tankyrase improves insulin sensitivity and glucose uptake, its inhibition in skeletal muscle leads to development of insulin resistance. Evidently further studies are required to determine the broader perspective of tankyrase in other cellular systems in regulating insulin signaling and insulin resistance. Role of tankyrase in neuronal tissues/cells has not been tested. In the present study, we investigated the effect of tankyrase inhibition in insulin-sensitive and insulin-resistant Neuro-2a cells. Here, we report that XAV939 treatment, a tankyrase inhibitor, improves insulin-stimulated glucose uptake in insulin-sensitive as well as in insulin-resistant neuronal cells via AMP-activated protein kinase (AMPK) - AKT Substrate of 160 kDa (AS160) mediated pathway without affecting the phosphorylation/activation of AKT. AMPK inhibition by Compound C repressed XAV939 treatment mediated increase in glucose uptake, confirming the role of tankyrase in glucose uptake via AMPK. We show for the first time that inhibition of tankyrase significantly improves glucose uptake and insulin sensitivity of insulin-resistant neuronal cells via AMPK-AS160 mediated pathway. Our study demonstrates new mechanistic insights of tankyrase mediated regulation of insulin sensitivity as well as glucose uptake in neuronal cells.

JUP/plakoglobin is regulated by salt-inducible kinase 2, and is required for insulin-induced signalling and glucose uptake in adipocytes

BackgroundSalt-inducible kinase 2 (SIK2) is abundant in adipocytes, but downregulated in adipose tissue from individuals with obesity and insulin resistance. Moreover, SIK isoforms are required for normal insulin signalling and glucose uptake in adipocytes, but the underlying molecular mechanisms are currently not known. The adherens junction protein JUP, also termed plakoglobin or γ-catenin, has recently been reported to promote insulin signalling in muscle cells. ObjectiveThe objective of this study was to analyse if JUP is required for insulin signalling in adipocytes and the underlying molecular mechanisms of this regulation. MethodsCo-expression of SIK2 and JUP mRNA levels in adipose tissue from a human cohort was analysed. siRNA silencing and/or pharmacological inhibition of SIK2, JUP, class IIa HDACs and CRTC2 was employed in 3T3-L1- and primary rat adipocytes. JUP protein expression was analysed by western blot and mRNA levels by qPCR. Insulin signalling was evaluated by western blot as levels of phosphorylated PKB/Akt and AS160, and by monitoring the uptake of 3H-2-deoxyglucose. ResultsmRNA expression of SIK2 correlated with that of JUP in human adipose tissue. SIK2 inhibition or silencing resulted in downregulation of JUP mRNA and protein expression in 3T3-L1- and in primary rat adipocytes. Moreover, JUP silencing reduced the expression of PKB and the downstream substrate AS160, and consequently attenuated activity in the insulin signalling pathway, including insulin-induced glucose uptake. The known SIK2 substrates CRTC2 and class IIa HDACs were found to play a role in the SIK-mediated regulation of JUP expression. ConclusionsThese findings identify JUP as a novel player in the regulation of insulin sensitivity in adipocytes, and suggest that changes in JUP expression could contribute to the effect of SIK2 on insulin signalling in these cells.

Regulation of lymphatic function and injury by nitrosative stress in obese mice

ObjectiveObesity results in lymphatic dysfunction, but the cellular mechanisms that mediate this effect remain largely unknown. Previous studies in obese mice have shown that inducible nitric oxide synthase-expressing (iNOS+) inflammatory cells accumulate around lymphatic vessels. In the current study, we therefore tested the hypothesis that increased expression of iNOS results in nitrosative stress and injury to the lymphatic endothelial cells (LECs). In addition, we tested the hypothesis that lymphatic injury, independent of obesity, can modulate glucose and lipid metabolism. MethodsWe compared the metabolic changes and lymphatic function of wild-type and iNOS knockout mice fed a normal chow or high-fat diet for 16 weeks. To corroborate our in vivo findings, we analyzed the effects of reactive nitrogen species on isolated LECs. Finally, using a genetically engineered mouse model that allows partial ablation of the lymphatic system, we studied the effects of acute lymphatic injury on glucose and lipid metabolism in lean mice. ResultsThe mesenteric lymphatic vessels of obese wild-type animals were dilated, leaky, and surrounded by iNOS+ inflammatory cells with resulting increased accumulation of reactive nitrogen species when compared with lean wild-type or obese iNOS knockout animals. These changes in obese wild-type mice were associated with systemic glucose and lipid abnormalities, as well as decreased mesenteric LEC expression of lymphatic-specific genes, including vascular endothelial growth factor receptor 3 (VEGFR-3) and antioxidant genes as compared with lean wild-type or obese iNOS knockout animals. In vitro experiments demonstrated that isolated LECs were more sensitive to reactive nitrogen species than blood endothelial cells, and that this sensitivity was ameliorated by antioxidant therapies. Finally, using mice in which the lymphatics were specifically ablated using diphtheria toxin, we found that the interaction between metabolic abnormalities caused by obesity and lymphatic dysfunction is bidirectional. Targeted partial ablation of mesenteric lymphatic channels of lean mice resulted in increased accumulation of iNOS+ inflammatory cells and increased reactive nitrogen species. Lymphatic ablation also caused marked abnormalities in insulin sensitivity, serum glucose and insulin concentrations, expression of insulin-sensitive genes, lipid metabolism, and significantly increased systemic and mesenteric white adipose tissue (M-WAT) inflammatory responses. ConclusionsOur studies suggest that increased iNOS production in obese animals plays a key role in regulating lymphatic injury by increasing nitrosative stress. In addition, our studies suggest that obesity-induced lymphatic injury may amplify metabolic abnormalities by increasing systemic and local inflammatory responses and regulating insulin sensitivity. These findings suggest that manipulation of the lymphatic system may represent a novel means of treating metabolic abnormalities associated with obesity.

Regulation of hepatic insulin signaling and glucose homeostasis by sphingosine kinase 2

Sphingolipid dysregulation is often associated with insulin resistance, while the enzymes controlling sphingolipid metabolism are emerging as therapeutic targets for improving insulin sensitivity. We report herein that sphingosine kinase 2 (SphK2), a key enzyme in sphingolipid catabolism, plays a critical role in the regulation of hepatic insulin signaling and glucose homeostasis both in vitro and in vivo. Hepatocyte-specific Sphk2 knockout mice exhibit pronounced insulin resistance and glucose intolerance. Likewise, SphK2-deficient hepatocytes are resistant to insulin-induced activation of the phosphoinositide 3-kinase (PI3K)-Akt-FoxO1 pathway and elevated hepatic glucose production. Mechanistically, SphK2 deficiency leads to the accumulation of sphingosine that, in turn, suppresses hepatic insulin signaling by inhibiting PI3K activation in hepatocytes. Either reexpressing functional SphK2 or pharmacologically inhibiting sphingosine production restores insulin sensitivity in SphK2-deficient hepatocytes. In conclusion, the current study provides both experimental findings and mechanistic data showing that SphK2 and sphingosine in the liver are critical regulators of insulin sensitivity and glucose homeostasis.

Sex dimorphism in the associations of gestational diabetes with cord blood adiponectin and retinol-binding protein 4

IntroductionGestational diabetes (GD) is associated with impaired insulin sensitivity in newborns. Adiponectin and retinol-binding protein 4 (RBP-4) are involved in regulating insulin sensitivity. Females are more likely to develop diabetes...

Oleic Acid Protects Against Insulin Resistance by Regulating the Genes Related to the PI3K Signaling Pathway.

Background: The effects of different types of fatty acids on the gene expression of key players in the IRS1/PI3K signaling pathway have been poorly studied. Material and Methods: We analyzed IRS1, p85α, and p110β mRNA expression and the fatty acid composition of phospholipids in visceral adipose tissue from patients with morbid obesity and from non-obese patients. Moreover, we analyzed the expression of those genes in visceral adipocytes incubated with oleic, linoleic, palmitic and dosahexaenoic acids. Results: We found a reduced IRS1 expression in patients with morbid obesity, independent of insulin resistance, and a reduced p110β expression in those with lower insulin resistance. A positive correlation was found between p85α and stearic acid, and between IRS1 and p110β with palmitic and dosahexaenoic acid. In contrast, a negative correlation was found between p85α and oleic acid, and between IRS1 and p110β with linoleic, arachidonic and adrenic acid. Incubation with palmitic acid decreased IRS1 expression. p85α was down-regulated after incubation with oleic and dosahexaenoic acid and up-regulated with palmitic acid. p110β expression was increased and decreased after incubation with oleic and palmitic acid, respectively. The ratio p85α/p110β was decreased by oleic and dosahexaenoic acid and increased by palmitic acid. Conclusions: Our in vitro results suggest a detrimental role of palmitic acid on the expression of gene related to insulin signaling pathway, with oleic acid being the one with the higher and more beneficial effects. DHA had a slight beneficial effect. Fatty acid-induced regulation of genes related to the IRS1/PI3K pathway may be a novel mechanism by which fatty acids regulate insulin sensitivity in visceral adipocytes.

Role of Histone Deacetylases in Skeletal Muscle Physiology and Systemic Energy Homeostasis: Implications for Metabolic Diseases and Therapy.

Skeletal muscle is the largest metabolic organ in the human body and is able to rapidly adapt to drastic changes during exercise. Histone acetyltransferases (HATs) and histone deacetylases (HDACs), which target histone and non-histone proteins, are two major enzyme families that control the biological process of histone acetylation and deacetylation. Balance between these two enzymes serves as an essential element for gene expression and metabolic and physiological function. Genetic KO/TG murine models reveal that HDACs possess pivotal roles in maintaining skeletal muscles’ metabolic homeostasis, regulating skeletal muscles motor adaptation and exercise capacity. HDACs may be involved in mitochondrial remodeling, insulin sensitivity regulation, turn on/off of metabolic fuel switching and orchestrating physiological homeostasis of skeletal muscles from the process of myogenesis. Moreover, many myogenic factors and metabolic factors are modulated by HDACs. HDACs are considered as therapeutic targets in clinical research for treatment of cancer, inflammation, and neurological and metabolic-related diseases. This review will focus on physiological function of HDACs in skeletal muscles and provide new ideas for the treatment of metabolic diseases.

In utero low-protein-diet-programmed type 2 diabetes in adult offspring is mediated by sex hormones in rats†.

Sex steroids regulate insulin sensitivity and glucose metabolism. We had characterized a lean type 2 diabetes (T2D) rat model using gestational low-protein (LP) diet programming. Our objective was to identify if endocrine dysfunction leading to decreased sex hormone levels will precede the development of T2D and if steroid replacement will prevent the onset of the disease. Pregnant rats were fed control or isocaloric LP diet from gestational day 4 until delivery. Normal diet was given to all mothers after delivery and to pups after weaning. LP offspring developed glucose intolerance and insulin resistance at 4months. We measured sex steroid hormone profiles and expression of key genes involved in steroidogenesis in testis and ovary. Furthermore, one-month old rats were implanted with 90-day slow release T and E2 pellets for males and females, respectively. Glucose tolerance test (GTT) and euglycemic hyperinsulinemic clamp was performed at 4months. LP-programmed T2D males had low T levels and females had low E2 levels due to dysregulated gene expression during steroidogenesis in gonads. GTT and euglycemic hyperinsulinemic clamp showed that LP males and females were glucose intolerant and insulin resistant; however, steroid supplementation prevented the onset of glucose intolerance and insulin resistance. Rats that developed T2D by LP programming have compromised gonadal steroidogenesis leading to low T and E2 in males and females, respectively. Sex steroid supplementation prevented the onset of glucose intolerance and insulin resistance indicating low sex steroid levels could cause compromised glucose metabolism ultimately leading to T2D.

Towards an Insulin Resistant Adipose Model on a Chip.

Adipose tissue and adipocytes are primary regulators of insulin sensitivity and energy homeostasis. Defects in insulin sensitivity of the adipocytes predispose the body to insulin resistance (IR) that could lead to diabetes. However, the mechanisms mediating adipocyte IR remain elusive, which emphasizes the need to develop experimental models that can validate the insulin signaling pathways and discover new mechanisms in the search for novel therapeutics. Currently in vitro adipose organ-chip devices show superior cell function over conventional cell culture. However, none of these models represent disease states. Only when these in vitro models can represent both healthy and disease states, they can be useful for developing therapeutics. Here, we establish an organ-on-chip model of insulin-resistant adipocytes, as well as characterization in terms of insulin signaling pathway and lipid metabolism. We differentiated, maintained, and induced insulin resistance into primary adipocytes in a microfluidic organ-on-chip. We then characterized IR by looking at the insulin signaling pathway and lipid metabolism, and validated by studying a diabetic drug, rosiglitazone. We confirmed the presence of insulin resistance through reduction of Akt phosphorylation, Glut4 expression, Glut4 translocation and glucose uptake. We also confirmed defects of disrupted insulin signaling through reduction of lipid accumulation from fatty acid uptake and elevation of glycerol secretion. Testing with rosiglitazone showed a significant improvement in insulin sensitivity and fatty acid metabolism as suggested by previous reports. The adipose-chip exhibited key characteristics of IR and can serve as model to study diabetes and facilitate discovery of novel therapeutics.

홍삼추출물(KGC05P0)이 고인슐린혈증 제2형 당뇨병 마우스에서 인슐린 민감성, 인슐린 분비량 및 혈당 조절에 미치는 영향

본 연구에서는 홍삼 비사포닌 분획 추출물(KGC05P0)이 인슐린 민감성 향상과 아디포넥틴의 연관성 및 그에 따른 혈당변화에 미치는 영향을 확인하기 위하여 고인슐린혈증 및 제2형 당뇨 동물모델에서 간조직의 인슐린 민감도 활성 단백질, 혈중 포도당 수치, 혈중 인슐린 수치, 혈중 아디포넥틴 수치의 변화를 살펴보았다. 그 결과 인슐린 민감성을 향상시키는 단백질 발현 증가와 혈중 아디포넥틴 수치 증가 및 공복혈당, 인슐린 농도를 감소시켜 고인슐린혈증 억제 및 항당뇨 효과를 나타내는 것을 확인하였다. 특히 KGC05P0은 양성대조군인 metformin과 유사한 수준으로 지표들을 개선하여 metformin이 나타낼 수 있는 lactic acidosis와 같은 부작용이 없고 건강한 혈당 유지에 도움을 주는 소재로 사용가능성을 시사하였다. 따라서 KGC05P0는 고인슐린혈증의 제2형 당뇨병 모델에서 간기능의 향상과 함께 인슐린 민감성과 관련된 지표들의 활성화를 통해 혈당 조절에 효능이 있음을 확인하였다.

Exercise and metabolic health: beyond skeletal muscle.

Regular exercise is a formidable regulator of insulin sensitivity and overall systemic metabolism through both acute events driven by each exercise bout and through chronic adaptations. As a result, regular exercise significantly reduces the risks for chronic metabolic disease states, including type 2 diabetes and non-alcoholic fatty liver disease. Many of the metabolic health benefits of exercise depend on skeletal muscle adaptations; however, there is plenty of evidence that exercise exerts many of its metabolic benefit through the liver, adipose tissue, vasculature and pancreas. This review will highlight how exercise reduces metabolic disease risk by activating metabolic changes in non-skeletal-muscle tissues. We provide an overview of exercise-induced adaptations within each tissue and discuss emerging work on the exercise-induced integration of inter-tissue communication by a variety of signalling molecules, hormones and cytokines collectively named 'exerkines'. Overall, the evidence clearly indicates that exercise is a robust modulator of metabolism and a powerful protective agent against metabolic disease, and this is likely to be because it robustly improves metabolic function in multiple organs. Graphical abstract.

1752-P: Discovery of Targets for Insulin Resistance by Microfluidic Organ-on-Chip Models

Metabolism of glucose and lipids is essential for nutrient balance and metabolic homeostasis, and is dynamically regulated by adipose tissue and liver. Dysfunction in regulation of these molecules as well as the secreted factors results in metabolic syndrome and insulin resistance (IR), which is a precursor to type 2 diabetes. Studies have shown that as the main site of adaptive thermogenesis, brown adipose tissue (BAT) improves hepatic insulin sensitivity, whereas white adipose tissue (WAT) can induce hepatic IR. However, how these organs communicate to regulate insulin sensitivity is not completely understood due to the lack of representative experimental models. Animals models are useful but suffer from confounding effects from other organs; traditional in vitro models have limited physiological representation. We have developed an organ-on-chip platform to study the interactions between BAT/WAT and liver under different metabolic states. The adipose-liver organ-chip consists of two interconnected microfluidic devices - brown/white adipocytes were cultured in one device and hepatocytes (insulin sensitive and IR) in the other, both under perfusion. We show that (a) adipocytes exhibited higher intracellular lipid and fatty acid secretion and (b) the hepatocytes secreted higher albumin compared to traditional co-cultures. We found that brown adipocytes secretions restored insulin sensitivity, and improved glucose/lipid metabolism in IR hepatocytes. In contrast, white adipocytes worsened insulin sensitivity and glucose/lipid metabolism. IR hepatocytes lowered Akt-phosphorylation and glucose uptake while upregulated adipocyte fatty acids secretion. Through RNA-seq, we have identified adipose genes responsible for improving hepatic IR. We have discovered potential new targets for improving hepatic insulin sensitivity. The novel organ-chip platform represented the cells physiologically and will be useful in the discovery and validation of new therapeutic targets for T2D. Disclosure N. Tanataweethum: None. A. Trang: None. L. Annepureddy: None. J. Mehta: None. R.N. Cohen: None. A. Bhushan: None. Funding DRTC (P30DK020595)

1886-P: Serum Dihydroceramides Predict Insulin Sensitivity in Humans and Cause Insulin Resistance In Vitro

Serum ceramides are related to insulin resistance, decrease after insulin sensitizing lifestyle interventions, and are linked to CVD risk in humans. To what extent other serum sphingolipids may serve to regulate insulin sensitivity remains unknown. We performed this study to quantify a broad range of serum sphingolipids in individuals spanning the physiologic range of insulin sensitivity, and to determine if specific sphingolipid species promote insulin resistance in vitro. We evaluated serum sphingolipid content in lean (n=15), endurance trained athletes (n=16), obese (n=15), and people with type 2 diabetes (T2D; n=12). Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps and serum sphingolipids measured using targeted lipidomics. Quantitative sphingolipid analysis revealed no differences between sphinganine, sphingosine, glucosyl- and lactosyl-ceramides, gangliosides, sphingomyelins, and sulfatides. Total serum ceramides were significantly increased in obese compared to lean individuals (p=0.01), with significant inverse relationships between C18:0 (p=0.002), C20:0 (p=0.02), and C22:0 (p-0.009) species and insulin sensitivity. Total serum dihydroceramides (p=0.0007) and most individual species were significantly greater in obese and T2D compared to lean and athletes, with C18:0 dihydroceramide showing the strongest inverse relationship to insulin sensitivity (p=0.002). We administered C18:0 dihydroceramide in liposomes to primary cultured myocytes and found that it significantly decreased insulin sensitivity in vitro by 36 +/- 6% (p=0.002), measured by insulin-stimulated glycogen synthesis. These data extend what is known regarding ceramides and insulin resistance and show a novel potential role for serum dihydroceramides, especially C18:0 species, in predicting and promoting insulin resistance in humans. Disclosure S. Zarini: None. J.T. Brozinick: Employee; Self; Eli Lilly and Company. L. Perreault: Advisory Panel; Self; Novo Nordisk Inc., Sanofi. Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk Inc. S.A. Newsom: None. D.E. Kahn: None. A. Kerege: None. K.A. Harrison: None. B.C. Bergman: Consultant; Spouse/Partner; Novo Nordisk Inc., Sanofi US. Research Support; Self; Eli Lilly and Company. Speaker’s Bureau; Spouse/Partner; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc. Funding National Institutes of Health (R01DK089170, T32DK07658, P30DK048520, RR-00036)

Implications of Skeletal Muscle Extracellular Matrix Remodeling in Metabolic Disorders: Diabetes Perspective.

The extracellular matrix (ECM) provides a scaffold for cells, controlling biological processes and providing structural as well as mechanical support to surrounding cells. Disruption of ECM homeostasis results in several pathological conditions. Skeletal muscle ECM is a complex network comprising collagens, proteoglycans, glycoproteins, and elastin. Recent therapeutic approaches targeting ECM remodeling have been extensively deliberated. Various ECM components are typically found to be augmented in the skeletal muscle of obese and/or diabetic humans. Skeletal muscle ECM remodeling is thought to be a feature of the pathogenic milieu allied with metabolic dysregulation, obesity, and eventual diabetes. This narrative review explores the current understanding of key components of skeletal muscle ECM and their specific roles in the regulation of metabolic diseases. Additionally, we discuss muscle-specific integrins and their role in the regulation of insulin sensitivity. A better understanding of the importance of skeletal muscle ECM remodeling, integrin signaling, and other factors that regulate insulin activity may help in the development of novel therapeutics for managing diabetes and other metabolic disorders.

MiR-378b Regulates Insulin Sensitivity by Targeting Insulin Receptor and p110α in Alcohol-Induced Hepatic Steatosis.

Insulin resistance has been implicated in alcoholic liver disease. A previous study has shown that microRNAs (miRNAs) play a major role in the production, secretion, and function of insulin. MiRNAs are capable of repressing multiple target genes that in turn negatively regulate various physiological and pathological activities. However, current information on the biological function of miRNAs in insulin resistance is limited. The goal of the present study was to elucidate the role of miR-378b in alcohol-induced hepatic insulin resistance and its underlying mechanism. This study has observed that miR-378b is up-regulated in National Institute on Alcohol Abuse and Alcoholism (NIAAA) alcoholic mouse models as well as in ethanol-induced L-02 cells in vitro. Furthermore, miR-378b overexpression impaired the insulin signaling pathway, and inhibition of miR-378b improved insulin sensitivity in vivo and in vitro. A mechanistic study revealed that IR and p110α are direct targets of miR-378b. Together, these results suggest that miR-378b controls insulin sensitivity by targeting the insulin receptor (IR) as well as p110α and possibly play an inhibitory role in the development of insulin resistance, thereby providing insights into the development of novel diagnostic and treatment methods.

The vascular epigenome in patients with obesity and type 2 diabetes: opportunities for personalized therapies

Our genetic background provides limited information on individual risk of developing vascular complications overtime. New biological layers, namely epigenetic modifications, are now emerging as potent regulators of gene expression thus leading to altered transcriptional programs and vascular disease phenotypes. Such epigenetic modifications, defined as changes to the genome that do not involve changes in DNA sequence, are generally induced by environmental factors and poor lifestyle habits. Of note, adverse epigenetic signals acquired during life can be transmitted to the offspring thus leading to premature alterations of the epigenetic and transcriptional landscape eventually leading to early endothelial dysfunction and vascular senescence. Modifications of the epigenome play a pivotal role in the pathophysiology of cardiometabolic disturbances such as obesity and type 2 diabetes. In these patients, changes of DNA methylation and chromatin structure contribute to alter pathways regulating insulin sensitivity, glucose homeostasis, adipogenesis and vascular function. In this perspective, unveiling the ‘epigenetic landscape’ in cardiometabolic patients may help to identify new players implicated in obesity and diabetes-related vascular dysfunction and may pave the way for personalized therapies in this setting. In the present review, we discuss current knowledge of the epigenetic routes implicated in vascular damage and cardiovascular disease in patients with metabolic alterations.

The association of Adiponectin polymorphism (rs2241766) with susceptibility and prognosis in Egyptian Hematological malignancies Patients: A case–control study

Background: Haematological malignancies are ranked as the highest in incidence. Adiponectin (ADIPOQ), the most abundant circulating adipocytokine, plays a major role in the regulation of insulin sensitivity, metabolism, and hematopoiesis. Various ADIPOQ gene polymorphisms are associated with an increased risk of different cancers. However, to the best of our knowledge, the association between ADIPOQ T45G (rs2241766) single nucleotide polymorphism (SNP) and leukemia is unknown. Aim: This study aimed to investigate the association between ADIPOQ (rs2241766) and the clinicopathological status of Egyptian leukemia patients. Materials and Methods: A case-control design was used, including 80 leukemia patients and 70 healthy controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for genotyping. Survival analysis and biochemical investigations including hematological and lipid profiles, liver and kidney functions in addition to anthropometric measurements were also determined. Results: A significant positive correlation between ADIPOQ gene T45G (rs2241766) SNP and leukemia incidence was detected. The G allele was more frequent in leukemia patients compared to the T allele. Kaplan-Meier analysis revealed that the SNP rs2241766was associated with the patient’s event-free survival but not the overall survival. In addition, G carriers, hyperglycemia, and hyperuricemia patients had a significantly shorter median EFS compared with T carriers, normoglycaemia, and normoglycemia patients. Conclusion: The current study shows an association between the SNP (rs2241766) and leukemia incidence and prognosis in Egyptian patients. Furthermore, an association between the rs2241766 and high prevalence of hyperglycemia and dyslipidemia in the G allele carrier’s leukemia patients was also evident.

Postnatal overfeeding induces hepatic microRNA-221 expression and impairs the PI3K/AKT pathway in adult male rats.

Increasing evidence suggests that postnatal overfeeding induces childhood obesity, which is strongly associated with metabolic syndrome. Insulin resistance is a risk factor for metabolic syndrome. MicroRNA-221 (miR-221) is involved in the development of obesity and has been reported to negatively regulate insulin sensitivity. However, the underlying mechanism remains unclear. Rats raised in small litters (SLs, three pups/dam, n = 10) and normal litters (NLs, 10 pups/dam, n = 10) were used to model early postnatal overfeeding and act as controls, respectively. miR-221 and proteins related to the phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT) pathway were assessed in the liver. Early postnatal overfeeding significantly increased body weight, visceral fat index, blood glucose, serum triglycerides, and the homeostasis model assessment of insulin resistance at 9 weeks. Real-time polymerase chain reaction (PCR) and western blot analysis revealed that postnatal overfeeding induced insulin receptor and insulin receptor substrate 2 expression, but decreased PI3K and AKT phosphorylation in the liver. Quantitative real-time PCR showed that hepatic miR-221 was significantly overexpressed in the SL group. These results indicate that postnatal overfeeding induces hepatic miR-221 overexpression and impairs the PI3K/AKT signal pathway, which may cause insulin resistance. We first report postnatal overfeeding induces hepatic miR-221 expression. Postnatal overfeeding impairs PI3K/AKT pathway in the liver of adult rats. Postnatal overfeeding induces obesity and high blood glucose. Avoidance of overfeeding during early postnatal life may prevent obesity and T2DM.

A novel CLK1‐THRAP3‐PPARγ axis is involved in the regulation of insulin sensitivity

Increasing energy expenditure by promoting “browning” in adipose tissues is a promising strategy to prevent obesity and associated diabetes. To explore potential targets of cold exposure, which induces energy expenditure, we performed phosphoproteomics profiling in brown adipose tissue of mice that were housed in mild cold exposure at 16°C. We identified that CLK1 (CDC2‐like kinase 1) is one of the kinases that were significantly downregulated by mild cold exposure. In addition, chemical inhibition or genetic knockout of CLK1 in mice prevented diet‐induced obesity and insulin resistance at 22°C. By proteomics approach, we uncovered a protein, THRAP3 (thyroid hormone receptor‐associated protein 3), as an interacting partner of CLK1, which was confirmed by co‐immunoprecipitation assays. We further identified that CLK1 phosphorylated THRAP3 at Ser243, required for interaction with phosphorylated PPARγ (peroxisome proliferator activated receptor gamma), resulting in downregulation of adipsin expression in adipose tissue and insulin sensitivity. These data suggest that CLK1 plays a critical role in controlling energy expenditure through the CLK1‐Thrap3‐PPARγ axis.Support or Funding InformationThe studies were supported by NIH grants HL122664 (to L. Chang), HL068878 (to Y.E. Chen)