scholarly journals Caveolin-1 Loss of Function Accelerates Glucose Transporter 4 and Insulin Receptor Degradation in 3T3-L1 Adipocytes

Endocrinology ◽  
2009 ◽  
Vol 150 (8) ◽  
pp. 3493-3502 ◽  
Author(s):  
Elena González-Muñoz ◽  
Carmen López-Iglesias ◽  
Maria Calvo ◽  
Manuel Palacín ◽  
Antonio Zorzano ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Cell Lines ◽  
Glucose Transporter ◽  
Lentiviral Vectors ◽  
Receptor Activation ◽  
Receptor Protein ◽  
Membrane Microdomains ◽  
Glucose Transporter 4 ◽  
Loss Of Function ◽  
Caveolin 1

Caveolae are a specialized type of lipid rafts that are stabilized by oligomers of caveolin protein. Caveolae are particularly enriched in adipocytes. Here we analyzed the effects of caveolin-1 knockdown and caveolae ablation on adipocyte function. To this end, we obtained several multiclonal mouse 3T3-L1 cell lines with a reduced expression of caveolin-1 (95% reduction) by a small interfering RNA approach using lentiviral vectors. Control cell lines were obtained by lentiviral infection with lentiviral vectors encoding appropriate scrambled RNAs. Caveolin-1 knockdown adipocytes showed a drastic reduction in the number of caveolae (95% decrease) and cholera toxin labeling was reorganized in dynamic plasma membrane microdomains. Caveolin-1 depletion caused a specific decrease in glucose transporter 4 (GLUT4) and insulin receptor protein levels. This reduction was not the result of a generalized defect in adipocyte differentiation or altered gene expression but was explained by faster degradation of these proteins. Caveolin-1 knockdown adipocytes showed reductions in insulin-stimulated glucose transport, insulin-triggered GLUT4 recruitment to the cell surface, and insulin receptor activation. In all, our data indicate that caveolin-1 loss of function reduces maximal insulin response through lowered stability and diminished expression of insulin receptors and GLUT4. We propose that caveolin-1/caveolae control insulin action in adipose cells.

scholarly journals Essential Role of Insulin Receptor Substrate 1 in Differentiation of Brown Adipocytes

2001 ◽  
Vol 21 (1) ◽  
pp. 319-329 ◽  
Author(s):  
Mathias Fasshauer ◽  
Johannes Klein ◽  
Kristina M. Kriauciunas ◽  
Kohjiro Ueki ◽  
Manuel Benito ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Cell Lines ◽  
Fatty Acid Synthase ◽  
Glucose Transporter ◽  
Uncoupling Protein ◽  
Brown Adipocyte ◽  
Insulin Receptor Substrate ◽  
Differentiation Process ◽  
Wild Type

ABSTRACT The most widely distributed members of the family of insulin receptor substrate (IRS) proteins are IRS-1 and IRS-2. These proteins participate in insulin and insulin-like growth factor 1 signaling, as well as the actions of some cytokines, growth hormone, and prolactin. To more precisely define the specific role of IRS-1 in adipocyte biology, we established brown adipocyte cell lines from wild-type and IRS-1 knockout (KO) animals. Using differentiation protocols, both with and without insulin, preadipocyte cell lines derived from IRS-1 KO mice exhibited a marked decrease in differentiation and lipid accumulation (10 to 40%) compared to wild-type cells (90 to 100%). Furthermore, IRS-1 KO cells showed decreased expression of adipogenic marker proteins, such as peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), fatty acid synthase, uncoupling protein-1, and glucose transporter 4. The differentiation deficit in the KO cells could be reversed almost completely by retrovirus-mediated reexpression of IRS-1, PPARγ, or C/EBPα but not the thiazolidinedione troglitazone. Phosphatidylinositol 3-kinase (PI 3-kinase) assays performed at various stages of the differentiation process revealed a strong and transient activation in IRS-1, IRS-2, and phosphotyrosine-associated PI 3-kinase in the wild-type cells, whereas the IRS-1 KO cells showed impaired phosphotyrosine-associated PI 3-kinase activation, all of which was associated with IRS-2. Akt phosphorylation was reduced in parallel with the total PI 3-kinase activity. Inhibition of PI 3-kinase with LY294002 blocked differentiation of wild-type cells. Thus, IRS-1 appears to be an important mediator of brown adipocyte maturation. Furthermore, this signaling molecule appears to exert its unique role in the differentiation process via activation of PI 3-kinase and its downstream target, Akt, and is upstream of the effects of PPARγ and C/EBPα.

Di(2-ethylhexyl)phthalate exposure impairs insulin receptor and glucose transporter 4 gene expression in L6 myotubes

2013 ◽  
Vol 33 (7) ◽  
pp. 685-700 ◽  
Author(s):  
P Rajesh ◽  
K Balasubramanian
Keyword(s):  
Gene Expression ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Insulin Signaling ◽  
Glucose Transporter ◽  
Negative Influence ◽  
Receptor Protein ◽  
Dependent Manner ◽  
L6 Myotubes ◽  
Dose Dependent

Di(2-ethyl hexyl)-phthalate (DEHP) is an endocrine disrupter and is the most abundantly used phthalate derivative, which is suspected to be an inevitable environmental exposure contributing to the increasing incidence of type-2 diabetes in humans. Therefore, the present study was designed to address the dose-dependent effects of DEHP on insulin signaling molecules in L6 myotubes. L6 myotubes were exposed to different concentrations (25, 50, and 100 μM) of DEHP for 24 h. At the end of exposure, cells were utilized for assessing various parameters. Insulin receptor and glucose transporter4 (GLUT4) gene expression, insulin receptor protein concentration, glucose uptake and oxidation, and enzymatic and nonenzymatic antioxidants were significantly reduced, but glutamine fructose-6-phosphate amidotransferase, nitric oxide, lipid peroxidation, and reactive oxygen species levels were elevated in a dose-dependent manner in L6 myotubes exposed to DEHP. The present study in turn shows the direct adverse effect of DEHP on the expression of insulin receptor and GLUT4 gene, glucose uptake, and oxidation in L6 myotubes suggesting that DEHP exposure may have a negative influence on insulin signaling.

scholarly journals Role of Caveolin-3 and Glucose Transporter-4 in Isoflurane-induced Delayed Cardiac Protection

2010 ◽  
Vol 112 (5) ◽  
pp. 1136-1145 ◽  
Author(s):  
Yasuo M. Tsutsumi ◽  
Yoshitaka Kawaraguchi ◽  
Yousuke T. Horikawa ◽  
Ingrid R. Niesman ◽  
Michael W. Kidd ◽  
...  
Keyword(s):  
Infarct Size ◽  
Knockout Mice ◽  
Glucose Transporter ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Glucose Transporter 4 ◽  
Wild Type ◽  
Cardiac Protection ◽  
Caveolin 1 ◽  
Discontinuous Sucrose Gradient

Background Caveolae are small, flask-like invaginations of the plasma membrane. Caveolins are structural proteins found in caveolae that have scaffolding properties to allow organization of signaling. The authors tested the hypothesis that delayed cardiac protection induced by volatile anesthetics is caveolae or caveolin dependent. Methods An in vivo mouse model of ischemia-reperfusion injury with delayed anesthetic preconditioning (APC) was tested in wild-type, caveolin-1 knockout, and caveolin-3 knockout mice. Mice were exposed to 30 min of oxygen or isoflurane and allowed to recover for 24 h. After 24 h recovery, mice underwent 30-min coronary artery occlusion followed by 2 h of reperfusion at which time infarct size was determined. Biochemical assays were also performed in excised hearts. Results Infarct size as a percent of the area at risk was reduced by isoflurane in wild-type (24.0 +/- 8.8% vs. 45.1 +/- 10.1%) and caveolin-1 knockout mice (27.2 +/- 12.5%). Caveolin-3 knockout mice did not show delayed APC (41.5 +/- 5.0%). Microscopically distinct caveolae were observed in wild-type and caveolin-1 knockout mice but not in caveolin-3 knockout mice. Delayed APC increased the amount of caveolin-3 protein but not caveolin-1 protein in discontinuous sucrose-gradient buoyant fractions. In addition, glucose transporter-4 was increased in buoyant fractions, and caveolin-3/glucose transporter-4 colocalization was observed in wild-type and caveolin-1 knockout mice after APC. Conclusions These results show that delayed APC involves translocation of caveolin-3 and glucose transporter-4 to caveolae, resulting in delayed protection in the myocardium.

Expression of insulin receptor and glucose transporter-4 in the skeletal muscle of chronically stressed rats

2016 ◽  
Author(s):  
Ayodele Morakinyo ◽  
Bolanle Iranloye ◽  
Titilola Samuel ◽  
Adekunle Mofolorunso ◽  
Adefunke Adegoke
Keyword(s):  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Glucose Transporter ◽  
Glucose Transporter 4

scholarly journals Tsg101 Is Involved in the Sorting and Re-Distribution of Glucose Transporter-4 to the Sarcolemma Membrane of Cardiac Myocytes

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1936
Author(s):  
Kobina Essandoh ◽  
Shan Deng ◽  
Xiaohong Wang ◽  
Yutian Li ◽  
Qianqian Li ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Glucose Transporter ◽  
Ischemia Reperfusion ◽  
Susceptibility Gene ◽  
Cardiac Cells ◽  
Acid Oxidation ◽  
Glucose Transporter 4 ◽  
Loss Of Function ◽  
Glut 4 ◽  
Insulin Dependent

Cardiac cells can adapt to pathological stress-induced energy crisis by shifting from fatty acid oxidation to glycolysis. However, the use of glucose-insulin-potassium (GIK) solution in patients undergoing cardiac surgery does not alleviate ischemia/reperfusion (I/R)-induced energy shortage. This indicates that insulin-mediated translocation of glucose transporter-4 (Glut-4) is impaired in ischemic hearts. Indeed, cardiac myocytes contain two intracellular populations of Glut-4: an insulin-dependent non-endosomal pool (also referred to as Glut-4 storage vesicles, GSVs) and an insulin-independent endosomal pool. Tumor susceptibility gene 101 (Tsg101) has been implicated in the endosomal recycling of membrane proteins. In this study, we aimed to examine whether Tsg101 regulated the sorting and re-distribution of Glut-4 to the sarcolemma membrane of cardiomyocytes under basal and ischemic conditions, using gain- and loss-of-function approaches. Forced overexpression of Tsg101 in mouse hearts and isolated cardiomyocytes could promote Glut-4 re-distribution to the sarcolemma, leading to enhanced glucose entry and adenosine triphosphate (ATP) generation in I/R hearts which in turn, attenuation of I/R-induced cardiac dysfunction. Conversely, knockdown of Tsg101 in cardiac myocytes exhibited opposite effects. Mechanistically, we identified that Tsg101 could interact and co-localize with Glut-4 in the sarcolemma membrane of cardiomyocytes. Our findings define Tsg101 as a novel regulator of cardiac Glut-4 trafficking, which may provide a new therapeutic strategy for the treatment of ischemic heart disease.

Rutin potentiates insulin receptor kinase to enhance insulin-dependent glucose transporter 4 translocation

2014 ◽  
Vol 58 (6) ◽  
pp. 1168-1176 ◽  
Author(s):  
Chia-Yu Hsu ◽  
Hung-Yuan Shih ◽  
Yi-Chen Chia ◽  
Chia-Hung Lee ◽  
Hitoshi Ashida ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Glucose Transporter ◽  
Receptor Kinase ◽  
Glucose Transporter 4 ◽  
Insulin Dependent ◽  
Insulin Receptor Kinase

Role of caveolin and caveolae in insulin signaling and diabetes

2003 ◽  
Vol 285 (6) ◽  
pp. E1151-E1160 ◽  
Author(s):  
Alex W. Cohen ◽  
Terry P. Combs ◽  
Philipp E. Scherer ◽  
Michael P. Lisanti
Keyword(s):  
Insulin Receptor ◽  
Insulin Signaling ◽  
Cell Types ◽  
Critical Discussion ◽  
Signaling Cascades ◽  
Membrane Microdomains ◽  
Coat Proteins ◽  
Caveolin 1 ◽  
Unique Composition

Caveolae are specialized membrane microdomains present within the plasma membrane of the vast majority of cell types. They have a unique composition in that they are highly enriched in cholesterol, sphingolipids, and their coat proteins the caveolins (-1, -2, and -3). In recent years it has been recognized that caveolae act as signaling platforms, serving as a concentrating point for numerous signaling molecules, as well as regulating flux through many distinct signaling cascades. Although caveolae are found in a variety of cell types, they are most abundant in adipose tissue. This fact has led to the intense study of the function of these organelles in adipocytes. It has now become apparent that effective insulin signaling in the adipocyte may be strictly dependent on localization of at least two insulin-responsive elements to caveolae (insulin receptor and GLUT4), as well as on a direct functional interaction between caveolin-1 and the insulin receptor. We present a critical discussion of these recent findings.

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