scholarly journals Apelin and APJ regulation in adipose tissue and skeletal muscle of type 2 diabetic mice and humans

2010 ◽  
Vol 298 (6) ◽  
pp. E1161-E1169 ◽  
Author(s):  
Cédric Dray ◽  
Cyrille Debard ◽  
Jennifer Jager ◽  
Emmanuel Disse ◽  
Danièle Daviaud ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Receptor Expression ◽  
Diabetic Patients ◽  
Mrna Levels ◽  
Type 2 Diabetic Patients ◽  
Insulin Resistant ◽  
Type 2 Diabetic

Apelin, an adipocyte-secreted factor upregulated by insulin, is increased in adipose tissue (AT) and plasma with obesity. Apelin was recently identified as a new player in the control of glucose homeostasis. However, the regulation of apelin and APJ (apelin receptor) expression in skeletal muscle in relation to insulin resistance or type 2 diabetes is not known. Thus we studied apelin and APJ expression in AT and muscle in different mice models of obesity and in type 2 diabetic patients. In insulin-resistant high-fat (HF)-fed mice, apelin and APJ expression were increased in AT compared with control. This was not the case in AT of highly insulin-resistant db/ db mice. In skeletal muscle, apelin expression was similar in control and HF-fed mice and decreased in db/ db mice. APJ expression was decreased in both HF-fed and db/ db mice. Control subjects and type 2 diabetic patients were subjected to a hyperinsulinemic-euglycemic clamp, and tissues biopsies were obtained before and at the end of the clamp. There was no significant difference in basal apelin and APJ expression in AT and muscle between control and diabetic patients. However, apelin plasma levels were significantly increased in diabetic patients. During the clamp, hyperinsulinemia increased apelin and APJ expression in AT of control but not in diabetic subjects. In muscle, only APJ mRNA levels were increased in control but also in diabetic patients. Taken together, these data show that apelin and APJ expression in mice and humans is regulated in a tissue-dependent manner and according to the severity of insulin resistance.

Proteasome inhibition in skeletal muscle cells unmasks metabolic derangements in type 2 diabetes

2014 ◽  
Vol 307 (9) ◽  
pp. C774-C787 ◽  
Author(s):  
Lubna Al-Khalili ◽  
Thais de Castro Barbosa ◽  
Jörgen Östling ◽  
Julie Massart ◽  
Pablo Garrido Cuesta ◽  
...  
Keyword(s):  
Metabolic Disease ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Proteome Analysis ◽  
Diabetic Patients ◽  
Type 2 Diabetic Patients ◽  
Insulin Resistant ◽  
Type 2 Diabetic

Two-dimensional difference gel electrophoresis (2-D DIGE)-based proteome analysis has revealed intrinsic insulin resistance in myotubes derived from type 2 diabetic patients. Using 2-D DIGE-based proteome analysis, we identified a subset of insulin-resistant proteins involved in protein turnover in skeletal muscle of type 2 diabetic patients, suggesting aberrant regulation of the protein homeostasis maintenance system underlying metabolic disease. We then validated the role of the ubiquitin-proteasome system (UPS) in myotubes to investigate whether impaired proteasome function may lead to metabolic arrest or insulin resistance. Myotubes derived from muscle biopsies obtained from people with normal glucose tolerance (NGT) or type 2 diabetes were exposed to the proteasome inhibitor bortezomib (BZ; Velcade) without or with insulin. BZ exposure increased protein carbonylation and lactate production yet impaired protein synthesis and UPS function in myotubes from type 2 diabetic patients, marking the existence of an insulin-resistant signature that was retained in cultured myotubes. In conclusion, BZ treatment further exacerbates insulin resistance and unmasks intrinsic features of metabolic disease in myotubes derived from type 2 diabetic patients. Our results highlight the existence of a confounding inherent abnormality in cellular protein dynamics in metabolic disease, which is uncovered through concurrent inhibition of the proteasome system.

Adiponectin expression in adipose tissue is reduced in first-degree relatives of type 2 diabetic patients

2003 ◽  
Vol 284 (2) ◽  
pp. E443-E448 ◽  
Author(s):  
A. S. Lihn ◽  
T. Østergård ◽  
B. Nyholm ◽  
S. B. Pedersen ◽  
B. Richelsen ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
Subcutaneous Adipose Tissue ◽  
Diabetic Patients ◽  
Mrna Levels ◽  
Type 2 Diabetic Patients ◽  
Adiponectin Mrna ◽  
Subcutaneous Adipose ◽  
Type 2 Diabetic

Adiponectin is suggested to be an important mediator of insulin resistance. Therefore, we investigated the association between adiponectin and insulin sensitivity in 22 healthy first-degree relatives (FDR) to type 2 diabetic patients and 13 matched control subjects. Subcutaneous adipose tissue biopsies were taken before and after a hyperinsulinemic euglycemic clamp. FDR subjects were insulin resistant, as indicated by a reduced Mvalue (4.44 vs. 6.09 mg · kg−1· min−1, P < 0.05). Adiponectin mRNA expression was 45% lower in adipose tissue from FDR compared with controls ( P < 0.01), whereas serum adiponectin was similar in the two groups (6.4 vs. 6.6 μg/ml, not significant). Insulin infusion reduced circulating levels of adiponectin moderately (11–13%) but significantly in both groups ( P < 0.05). In the control group, adiponectin mRNA levels were negatively correlated with fasting insulin ( P < 0.05) and positively correlated with insulin sensitivity ( P < 0.05). In contrast, these associations were not found in the FDR group. In conclusion, FDR have reduced adiponectin mRNA in subcutaneous adipose tissue but normal levels of circulating adiponectin. Adiponectin mRNA levels are positively correlated with insulin sensitivity in control subjects but not in FDR. These findings indicate dysregulation of adiponectin gene expression in FDR.

Increased collagen content in insulin-resistant skeletal muscle

2006 ◽  
Vol 290 (3) ◽  
pp. E560-E565 ◽  
Author(s):  
Rachele Berria ◽  
Lishan Wang ◽  
Dawn K. Richardson ◽  
Jean Finlayson ◽  
Renata Belfort ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Collagen Content ◽  
Matrix Composition ◽  
Diabetic Patients ◽  
Type 2 Diabetic Patients ◽  
Insulin Resistant ◽  
Obese Subjects ◽  
Type 2 Diabetic

Oversupply and underutilization of lipid fuels are widely recognized to be strongly associated with insulin resistance in skeletal muscle. Recent attention has focused on the mechanisms underlying this effect, and defects in mitochondrial function have emerged as a potential player in this scheme. Because evidence indicates that lipid oversupply can produce abnormalities in extracellular matrix composition and matrix changes can affect the function of mitochondria, the present study was undertaken to determine whether muscle from insulin-resistant, nondiabetic obese subjects and patients with type 2 diabetes mellitus had increased collagen content. Compared with lean control subjects, obese and type 2 diabetic subjects had reduced muscle glucose uptake ( P < 0.01) and decreased insulin stimulation of tyrosine phosphorylation of insulin receptor substrate-1 and its ability to associate with phosphatidylinositol 3-kinase ( P < 0.01 and P < 0.05). Because it was assayed by total hydroxyproline content, collagen abundance was increased in muscle from not only type 2 diabetic patients but also nondiabetic obese subjects (0.26 ± 0.05, 0.57 ± 0.18, and 0.67 ± 0.20 μg/mg muscle wet wt, lean controls, obese nondiabetics, and type 2 diabetics, respectively), indicating that hyperglycemia itself could not be responsible for this effect. Immunofluorescence staining of muscle biopsies indicated that there was increased abundance of types I and III collagen. We conclude that changes in the composition of the extracellular matrix are a general characteristic of insulin-resistant muscle.

scholarly journals Decreased Expression Of apM1 in Omental and Subcutaneous Adipose Tissue of Humans With Type 2 Diabetes

2000 ◽  
Vol 1 (2) ◽  
pp. 81-88 ◽  
Author(s):  
Michael A. Statnick ◽  
Lisa S. Beavers ◽  
Laura J. Conner ◽  
Helena Corominola ◽  
Dwayne Johnson ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Adipose Tissue ◽  
Subcutaneous Adipose Tissue ◽  
Diabetic Patients ◽  
Mrna Levels ◽  
Type 2 Diabetic Patients ◽  
Omental Adipose Tissue ◽  
Subcutaneous Adipose ◽  
Type 2 Diabetic

We have screened a subtracted cDNA library in order to identify differentially expressed genes in omental adipose tissue of human patients with Type 2 diabetes. One clone (#1738) showed a marked reduction in omental adipose tissue from patients with Type 2 diabetes. Sequencing and BLAST analysis revealed clone #1738 was the adipocyte-specific secreted protein gene apM1 (synonyms ACRP30, AdipoQ, GBP28). Consistent with the murine orthologue, apM1 mRNA was expressed in cultured human adipocytes and not in preadipocytes. Using RT-PCR we confirmed that apM1 mRNA levels were significantly reduced in omental adipose tissue of obese patients with Type 2 diabetes compared with lean and obese normoglycemic subjects. Although less pronounced, apM1 mRNA levels were reduced in subcutaneous adipose tissue of Type 2 diabetic patients. Whereas the biological function of apM1 is presently unknown, the tissue specific expression, structural similarities to TNFα and the dysregulated expression observed in obese Type 2 diabetic patients suggest that this factor may play a role in the pathogenesis of insulin resistance and Type 2 diabetes.

Expression of the splice variants of the p85α regulatory subunit of phosphoinositide 3-kinase in muscle and adipose tissue of healthy subjects and type 2 diabetic patients

2001 ◽  
Vol 360 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Etienne LEFAI ◽  
Marina ROQUES ◽  
Nathalie VEGA ◽  
Martine LAVILLE ◽  
Hubert VIDAL
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Mrna Expression ◽  
Expression Profiles ◽  
Regulatory Subunit ◽  
Diabetic Patients ◽  
Type 2 Diabetic Patients ◽  
Phosphoinositide 3 Kinase ◽  
Type 2 Diabetic

The regulation by insulin of the expression of the p85α regulatory subunit of phosphoinositide 3-kinase (PI 3-kinase) is impaired in skeletal muscle and adipose tissue of type 2 diabetic patients. The gene encoding p85α (named grb-1) can generate several variants by alternative splicing, all being able to activate the p110 catalytic subunits of PI 3-kinase. Our aims were (i) to determine the mRNA expression profiles of these variants in human skeletal muscle and adipose tissue; (ii) to investigate the effect of insulin on their expression in vivo and in vitro in muscle and (iii) to verify whether this regulation is defective in type 2 diabetes. We determined the human genomic organization of grb-1 and set up reverse transcriptase competitive PCR assays for the quantification of each mRNA variant. In muscle, p85α and p50α mRNAs were the most abundant, and p55α represented less than 20% of all grb-1-derived mRNAs. In adipose tissue, p85α was expressed predominantly and p55α mRNA was not detectable. These expression profiles were not different in type 2 diabetics. During a 3h hyperinsulinaemic clamp, insulin increased the mRNA expression of the three variants in muscle of control subjects. In diabetic patients, the effect of insulin on p85α and p50α mRNAs was blunted, and largely reduced on p55α transcripts. In cultured human myotubes, up-regulation of p85α, p55α and p50α mRNAs by insulin was abolished by LY294002 (10μM) and by rapamycin (50nM), suggesting that the PI 3-kinase/protein kinase B/p70 S6 kinase pathway could be involved in the stimulation of grb-1 gene expression by insulin in human muscle cells.

Insulin-sensitive and insulin-resistant variants in nonobese Japanese type 2 diabetic patients. The role of triglycerides in insulin resistance

Diabetes Care ◽  
1999 ◽  
Vol 22 (12) ◽  
pp. 2100-2101 ◽  
Author(s):  
A. Taniguchi ◽  
M. Fukushima ◽  
M. Sakai ◽  
K. Kataoka ◽  
K. Miwa ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Diabetic Patients ◽  
Type 2 Diabetic Patients ◽  
Insulin Resistant ◽  
Type 2 Diabetic

scholarly journals Evidence of increased visceral obesity and reduced physical fitness in healthy insulin-resistant first-degree relatives of type 2 diabetic patients

2004 ◽  
pp. 207-214 ◽  
Author(s):  
B Nyholm ◽  
MF Nielsen ◽  
K Kristensen ◽  
S Nielsen ◽  
T Ostergard ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Visceral Obesity ◽  
Visceral Adiposity ◽  
Diabetic Patients ◽  
Vo2 Max ◽  
Type 2 Diabetic Patients ◽  
Insulin Resistant ◽  
History Of ◽  
Type 2 Diabetic

OBJECTIVE: First-degree relatives (FDR) of type 2 diabetic patients are often insulin resistant. Visceral obesity is closely linked to both insulin resistance and type 2 diabetes. We therefore hypothesized that the inheritance of an increased tendency to store fat in visceral fat depots may be a characteristic phenotypic feature in FDR contributing to their insulin resistance. DESIGN AND METHODS: We measured fat distribution in 20 FDR and 14 age-, gender- and body mass index (BMI)-matched controls employing dual energy X-ray absorbtiometry (DEXA)- and computed tomography (CT)-scanning. Insulin-stimulated glucose uptake (ISGU) was determined by a hyperinsulinemic clamp and maximal aerobic work capacity (VO2 max) by a bicycle ergometer test. Baseline lipolysis was measured using [3H]palmitate. The activity level of the hypothalamic-pituitary-adrenal axis was assessed as the 24 h urinary (u)-cortisol/creatinine ratio. RESULTS: All subjects had a normal oral glucose tolerance test (OGTT), but FDR were insulin resistant (ISGU: 6.64+/-0.48 vs 9.12+/-0.98 mg/kg ffm/min, P=0.01). Despite similar BMI (25.2+/-0.5 vs 24.8+/-0.7 kg/m2, P=0.61) and overall fat mass (26.4+/-1.6 vs 24.2+/-2.1%, P=0.41) in FDR vs controls, the amount of visceral adipose tissue was substantially increased (65.9+/-10.0 vs 40.1+/-11.3 cm2, P<0.05) and VO2 max was reduced (52.2+/-3.1 vs 63.3+/-3.9 ml/kg ffm/min, P<0.05) in FDR. Visceral adiposity was inversely correlated with ISGU (FDR: r=-0.52, P<0.05; controls: r=-0.65, P<0.01) and in multiple regression analysis visceral adiposity (P<0.01), VO2 max (P<0.001) and a family history of type 2 diabetes (P<0.05) (r2=0.64) all significantly and independently contributed to the level of ISGU. Baseline palmitate appearance (145+/-10 vs 139+/-15 micromol/min, P=0.74) and the 24 h u-cortisol/creatinine ratio ((24.9+/-1.3 vs 27.4+/-2.0).10(-6), P=0.28) were both comparable in the two groups. CONCLUSION: Healthy but insulin-resistant FDR have enhanced visceral obesity and reduced VO2 max compared with people without a family history of diabetes, despite similar BMI and overall fat mass. Both the visceral adiposity and reduced aerobic fitness are strongly associated with and may contribute to their insulin resistance.

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