scholarly journals Insulin Resistance in Skeletal Muscle Selectively Protects the Heart in Response to Metabolic Stress

Author(s):  
Dandan Jia ◽  
Jun Zhang ◽  
Xueling Liu ◽  
John-Paul Andersen ◽  
Zhenjun Tian ◽  
...  

<a>Obesity and type 2 diabetes mellitus (T2DM) are the leading causes of cardiovascular morbidity and mortality. Although insulin resistance is believed to underlie these disorders, </a><a>anecdotal evidence contradicts this common belief. Accordingly, obese patients with cardiovascular disease have better prognoses relative to leaner patients with the same diagnoses, whereas treatment of T2DM patients with thiazolidines, one of the popular insulin sensitizer drugs, significantly increases the risk of heart failure. </a>Using mice with skeletal muscle-specific <a>ablation of the insulin receptor </a>gene (MIRKO), we addressed this paradox by demonstrating that insulin signaling in skeletal muscles specifically mediated crosstalk with the heart, but not other metabolic tissues, to prevent cardiac dysfunction in response to metabolic stress. Despite severe hyperinsulinemia and aggregating obesity, MIRKO mice were protected from myocardial insulin resistance, mitochondrial dysfunction, and metabolic reprogramming in response to diet-induced obesity (DIO). Consequently, the MIRKO mice were also protected from myocardial inflammation, cardiomyopathy, and left ventricle dysfunction. Together, our findings suggest that insulin resistance in skeletal muscle functions as a double-edged sword in metabolic diseases.

2021 ◽  
Author(s):  
Dandan Jia ◽  
Jun Zhang ◽  
Xueling Liu ◽  
John-Paul Andersen ◽  
Zhenjun Tian ◽  
...  

<a>Obesity and type 2 diabetes mellitus (T2DM) are the leading causes of cardiovascular morbidity and mortality. Although insulin resistance is believed to underlie these disorders, </a><a>anecdotal evidence contradicts this common belief. Accordingly, obese patients with cardiovascular disease have better prognoses relative to leaner patients with the same diagnoses, whereas treatment of T2DM patients with thiazolidines, one of the popular insulin sensitizer drugs, significantly increases the risk of heart failure. </a>Using mice with skeletal muscle-specific <a>ablation of the insulin receptor </a>gene (MIRKO), we addressed this paradox by demonstrating that insulin signaling in skeletal muscles specifically mediated crosstalk with the heart, but not other metabolic tissues, to prevent cardiac dysfunction in response to metabolic stress. Despite severe hyperinsulinemia and aggregating obesity, MIRKO mice were protected from myocardial insulin resistance, mitochondrial dysfunction, and metabolic reprogramming in response to diet-induced obesity (DIO). Consequently, the MIRKO mice were also protected from myocardial inflammation, cardiomyopathy, and left ventricle dysfunction. Together, our findings suggest that insulin resistance in skeletal muscle functions as a double-edged sword in metabolic diseases.


Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Janine Krüger ◽  
Markus Dagnell ◽  
Philipp Stawowy ◽  
Evren Caglayan ◽  
Arne Östman ◽  
...  

Background: Insulin resistance plays a crucial role in the development of type 2 diabetes, and exerts great impact on vascular inflammation and remodeling. At the molecular level a post-insulin receptor (IR) defect in insulin signaling has been suggested to contribute to insulin resistance. IR signaling is antagonized and tightly controlled by protein tyrosine phosphatases (PTPs). The precise role of PTPs in insulin resistance, however, has not been explored. Results: Male C57BL/6J mice were fed a high-fat diet (HFD, 60% kcal from fat) to induce insulin resistance, or a low-fat diet (LFD, 10% kcal from fat) for 10 weeks. Afterwards, HFD mice were treated with PTP-inhibitors for additional 6 weeks. Mice under HFD exhibited a significant increase in body weight as well as decreased respiratory quotient and adiponectin levels, and were characterized by impaired insulin- and glucose tolerance. Organ-based gene expression analyses in insulin-resistant mice demonstrated upregulation of SHP-1, PTP1B, LAR, and DEP-1 in insulin-sensitive organs. SHP-1 was further explored in vitro. Insulin stimulation in murine liver cells induced site-selective hyper-phosphorylation at IR tyrosine-sites Y1158, and Y1361 after inhibition of SHP-1. Furthermore, SHP-1 impairment time-dependently enhanced insulin-induced Akt- and Erk-phosphorylation, and resulted in elevated glucose uptake in skeletal muscle cells. Administration of a SHP-1 inhibitor (Sodium Stibogluconate) and a brought pan-PTP inhibitor (BMOV) in HFD mice led to improvement of both insulin- and glucose tolerance. In accordance, PTP-activity was significantly impaired in epididymal fat, skeletal muscle, and liver under BMOV treatment, being confirmed by reduced ex vivo dephosphorylation of a radioactive labelled peptide (AEEEIYGEFEAKKKK). Finally, BMOV- and SHP-1 treatment also resulted in reduced body weight. Conclusions: IR-antagonizing PTPs were organ-specifically regulated in insulin resistance. The results indicate a central role of PTPs and, in particular, of SHP-1 as endogenous antagonists of the IR. Taken together targeting PTPs led to beneficial effects in insulin resistance, and may thus improve metabolic diseases as well as cardiovascular morbidity and mortality.


2020 ◽  
Author(s):  
Dandan Jia ◽  
Jun Zhang ◽  
Xueling Liu ◽  
John-Paul Anderson ◽  
Zhenjun Tian ◽  
...  

AbstractObesity and type 2 diabetes milieus (T2DM) are the leading causes of cardiovascular morbidity and mortality. Although insulin resistance is believed to underlie these disorders, a paradox exists that obese patients with cardiovascular diseases have better prognoses relative to leaner patients with the same diagnoses, whereas improvement of insulin sensitivity by thiazolidines significantly increases the risk of heart failure in T2DM patients. Using mice with skeletal muscle-specific deletion of the insulin receptor gene (MIRKO), we resolved this dilemma by demonstrating that insulin resistance in the skeletal muscle prevents myocardial hypertrophy and dysfunction in response to diet-induced obesity. In spite of aggregating obesity, insulin resistance selectively protected the heart, but not other metabolic tissues, from mitochondrial dysfunction and insulin resistance in MIRKO mice, leading to significant attenuation of inflammation and apoptosis of cardiomyocytes. Together, our findings revealed an unexpected role of insulin resistance as a double edge sword, calling for reevaluation of ongoing efforts for targeting insulin resistance for the treatment of metabolic diseases.Significance statementInsulin resistance is commonly recognized as one of the major causes of T2DM and other aging-related chronic diseases. However, cumulative efforts in targeting insulin resistance for the treatment of T2DM and other metabolic disorders have not met with great success due to unwanted side effects on heart failure. Here we report that insulin resistance in skeletal muscle is a double edge sword. On one hand, insulin resistance in skeletal muscle aggregates obesity and its related metabolic syndromes, and on the other it protects the heart from the development of myocardial hypertrophy, dysfunction, and apoptosis in response to DIO. Our findings call for reevaluation of the ongoing strategies in targeting insulin resistance as a novel treatment for T2DM and other metabolic diseases.


Author(s):  
Claire Laurens ◽  
Cedric Moro

AbstractOver the past decades, obesity and its metabolic co-morbidities such as type 2 diabetes (T2D) developed to reach an endemic scale. However, the mechanisms leading to the development of T2D are still poorly understood. One main predictor for T2D seems to be lipid accumulation in “non-adipose” tissues, best known as ectopic lipid storage. A growing body of data suggests that these lipids may play a role in impairing insulin action in metabolic tissues, such as liver and skeletal muscle. This review aims to discuss recent literature linking ectopic lipid storage and insulin resistance, with emphasis on lipid deposition in skeletal muscle. The link between skeletal muscle lipid content and insulin sensitivity, as well as the mechanisms of lipid-induced insulin resistance and potential therapeutic strategies to alleviate lipotoxic lipid pressure in skeletal muscle will be discussed.


1997 ◽  
Vol 273 (5) ◽  
pp. E915-E921 ◽  
Author(s):  
Carsten Schmitz-Peiffer ◽  
Nicholas D. Oakes ◽  
Carol L. Browne ◽  
Edward W. Kraegen ◽  
Trevor J. Biden

We have recently shown that the reduction in insulin sensitivity of rats fed a high-fat diet is associated with the translocation of the novel protein kinase Cε(nPKCε) from cytosolic to particulate fractions in red skeletal muscle and also the downregulation of cytosolic nPKCθ. Here we have further investigated the link between insulin resistance and PKC by assessing the effects of the thiazolidinedione insulin-sensitizer BRL-49653 on PKC isoenzymes in muscle. BRL-49653 increased the recovery of nPKC isoenzymes in cytosolic fractions of red muscle from fat-fed rats, reducing their apparent activation and/or downregulation, whereas PKC in control rats was unaffected. Because BRL-49653 also improves insulin-stimulated glucose uptake in fat-fed rats and reduces muscle lipid storage, especially diglyceride content, these results strengthen the association between lipid availability, nPKC activation, and skeletal muscle insulin resistance and support the hypothesis that chronic activation of nPKC isoenzymes is involved in the generation of muscle insulin resistance in fat-fed rats.


Author(s):  
Kimberley M Mellor ◽  
James R Bell ◽  
Rebecca H Ritchie ◽  
Lea MD Delbridge

2021 ◽  
Vol 22 (17) ◽  
pp. 9327
Author(s):  
Alessandra Feraco ◽  
Stefania Gorini ◽  
Andrea Armani ◽  
Elisabetta Camajani ◽  
Manfredi Rizzo ◽  
...  

Skeletal muscle is essential to maintain vital functions such as movement, breathing, and thermogenesis, and it is now recognized as an endocrine organ. Muscles release factors named myokines, which can regulate several physiological processes. Moreover, skeletal muscle is particularly important in maintaining body homeostasis, since it is responsible for more than 75% of all insulin-mediated glucose disposal. Alterations of skeletal muscle differentiation and function, with subsequent dysfunctional expression and secretion of myokines, play a key role in the pathogenesis of obesity, type 2 diabetes, and other metabolic diseases, finally leading to cardiometabolic complications. Hence, a deeper understanding of the molecular mechanisms regulating skeletal muscle function related to energy metabolism is critical for novel strategies to treat and prevent insulin resistance and its cardiometabolic complications. This review will be focused on both cellular and animal models currently available for exploring skeletal muscle metabolism and endocrine function.


2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Mei Han ◽  
Lianghui You ◽  
Yanting Wu ◽  
Nan Gu ◽  
Yan Wang ◽  
...  

Abstract Insulin resistance (IR) has been considered as the common pathological basis and developmental driving force for most metabolic diseases. Long noncoding RNAs (lncRNAs) have emerged as pivotal regulators in modulation of glucose and lipid metabolism. However, the comprehensive profile of lncRNAs in skeletal muscle cells under the insulin resistant status and the possible biological effects of them were not fully studied. In this research, using C2C12 myotubes as cell models in vitro, deep RNA-sequencing was performed to profile lncRNAs and mRNAs between palmitic acid-induced IR C2C12 myotubes and control ones. The results revealed that a total of 144 lncRNAs including 70 up-regulated and 74 down-regulated (|fold change| &gt; 2, q &lt; 0.05) were significantly differentially expressed in palmitic acid-induced insulin resistant cells. In addition, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases revealed that the target genes of the differentially expressed lncRNAs were significantly enriched in fatty acid oxidation, lipid oxidation, PPAR signaling pathway, and insulin signaling pathway. Moreover, Via qPCR, most of selected lncRNAs in myotubes and db/db mice skeletal muscle showed the consistent expression trends with RNA-sequencing. Co-expression analysis also explicated the key lncRNA–mRNA interactions and pointed out a potential regulatory network of candidate lncRNA ENSMUST00000160839. In conclusion, the present study extended the skeletal muscle lncRNA database and provided novel potential regulators for future genetic and molecular studies on insulin resistance, which is helpful for prevention and treatment of the related metabolic diseases.


Pharmacology ◽  
2021 ◽  
pp. 1-9
Author(s):  
Shaimaa El-Fayoumi ◽  
Rehab Mansour ◽  
Amr Mahmoud ◽  
Ahmed Fahmy ◽  
Islam Ibrahim

<b><i>Introduction:</i></b> Pioglitazone is a thiazolidinedione oral antidiabetic agent. This study aimed to investigate the effects of pioglitazone as insulin sensitizer on β-arrestin2 signaling in classical insulin target tissues. <b><i>Methods:</i></b> Experiments involved three groups of mice; the first one involved mice fed standard chow diet for 16 weeks; the second one involved mice fed high-fructose, high-fat diet (HFrHFD) for 16 weeks; and the third one involved mice fed HFrHFD for 16 weeks and received pioglitazone (30 mg/kg/day, orally) in the last four weeks of feeding HFrHFD. <b><i>Results:</i></b> The results showed significant improvement in the insulin sensitivity of pioglitazone-treated mice as manifested by significant reduction in the insulin resistance index. This improvement in insulin sensitivity was associated with significant increases in the β-arrestin2 levels in the adipose tissue, liver, and skeletal muscle. Moreover, pioglitazone significantly increased β-arrestin2 signaling in all the examined tissues as estimated from significant increases in phosphatidylinositol 4,5 bisphosphate and phosphorylation of Akt at serine 473 and significant decrease in diacylglycerol level. <b><i>Conclusion:</i></b> To the best of our knowledge, our work reports a new mechanism of action for pioglitazone through which it can enhance the insulin sensitivity. Pioglitazone increases β-arrestin2 signaling in the adipose tissue, liver, and skeletal muscle of HFrHFD-fed mice.


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