Skeletal muscle insulin resistance induced by adipocyte-conditioned medium: underlying mechanisms and reversibility

Insulin resistance in skeletal muscle is an early event in the development of diabetes, with obesity being one of the major contributing factors. In vitro, conditioned medium (CM) from differentiated human adipocytes impairs insulin signaling in human skeletal muscle cells, but it is not known whether insulin resistance is reversible and which mechanisms may underlie this process. CM induced insulin resistance in human myotubes at the level of insulin-stimulated Akt and GSK-3 phosphorylation. In addition, insulin-resistant skeletal muscle cells exhibit enhanced production of reactive oxygen species and ceramide as well as a downregulation of myogenic transcription factors such as myogenin and MyoD. However, insulin resistance was not paralleled by increased apopotosis. Regeneration of myotubes for 24 or 48 h after induction of insulin resistance restored normal insulin signaling. However, the expression level of myogenin could not be reestablished. In addition to decreasing myogenin expression, CM also decreased the release of IL-6 and IL-8 and increased monocyte chemotactic protein-1 (MCP-1) secretion from skeletal muscle cells. Although regeneration of myotubes reestablished normal secretion of IL-6, the release of IL-8 and MCP-1 remained impaired for 48 h after withdrawal of CM. In conclusion, our data show that insulin resistance in skeletal muscle cells is only partially reversible. Although some characteristic features of insulin-resistant myotubes normalize in parallel to insulin signaling after withdrawal of CM, others such as IL-8 and MCP-1 secretion and myogenin expression remain impaired over a longer period. Thus, we propose that the induction of insulin resistance may cause irreversible changes of protein expression and secretion in skeletal muscle cells.

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Gliclazide increases insulin receptor tyrosine phosphorylation but not p38 phosphorylation in insulin-resistant skeletal muscle cells

Journal of Experimental Biology ◽

10.1242/jeb.205.23.3739 ◽

2002 ◽

Vol 205 (23) ◽

pp. 3739-3746 ◽

Cited By ~ 1

Author(s):

Naresh Kumar ◽

Chinmoy S. Dey

Keyword(s):

Skeletal Muscle ◽

Insulin Receptor ◽

Glucose Uptake ◽

Tyrosine Phosphorylation ◽

Insulin Signaling ◽

Mapk Pathway ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Insulin Resistant ◽

Resistant Cells

SUMMARY Sulfonylurea drugs are used in the treatment of type 2 diabetes. The mechanism of action of sulfonylureas is to release insulin from pancreatic cells and they have been proposed to act on insulin-sensitive tissues to enhance glucose uptake. The goal of the present study was to test the hypothesis that gliclazide, a second-generation sulfonylurea, could enhance insulin signaling in insulin-resistant skeletal muscle cells. We demonstrated that gliclazide enhanced insulin-stimulated insulin receptor tyrosine phosphorylation in insulin-resistant skeletal muscle cells. Although insulin receptor substrate-1 tyrosine phosphorylation was unaffected by gliclazide treatment, phosphatidylinositol 3-kinase activity was partially restored by treatment with gliclazide. No increase in 2-deoxyglucose uptake in insulin-resistant cells by treatment with gliclazide was observed. Further investigations into the mitogen-activated protein kinase (MAPK) pathway revealed that insulin-stimulated p38 phosphorylation was impaired, as compared with extracellular-signal-regulated kinase (ERK) and c-Jun N-terminal kinase(JNK), which were phosphorylated normally in insulin-resistant cells. Treatment with gliclazide could not restore p38 phosphorylation in insulin-resistant cells. We propose that gliclazide can regulate part of the insulin signaling in insulin-resistant skeletal muscle, and p38 could be a potential therapeutic target for glucose uptake to treat insulin resistance.

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Contractile activity of human skeletal muscle cells prevents insulin resistance by inhibiting pro-inflammatory signalling pathways

Diabetologia ◽

10.1007/s00125-012-2454-z ◽

2012 ◽

Vol 55 (4) ◽

pp. 1128-1139 ◽

Cited By ~ 76

Author(s):

S. Lambernd ◽

A. Taube ◽

A. Schober ◽

B. Platzbecker ◽

S. W. Görgens ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Contractile Activity ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Signalling Pathways ◽

Human Skeletal Muscle Cells ◽

Inflammatory Signalling

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Leucine modulates dynamic phosphorylation events in insulin signaling pathway and enhances insulin-dependent glycogen synthesis in human skeletal muscle cells

BMC Cell Biology ◽

10.1186/1471-2121-15-9 ◽

2014 ◽

Vol 15 (1) ◽

pp. 9 ◽

Cited By ~ 13

Author(s):

Barbara Di Camillo ◽

Federica Eduati ◽

Sreekumaran K Nair ◽

Angelo Avogaro ◽

Gianna M Toffolo

Keyword(s):

Skeletal Muscle ◽

Signaling Pathway ◽

Insulin Signaling ◽

Human Skeletal Muscle ◽

Glycogen Synthesis ◽

Muscle Cells ◽

Insulin Signaling Pathway ◽

Skeletal Muscle Cells ◽

Human Skeletal Muscle Cells ◽

Insulin Dependent

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Induction of insulin resistance in human skeletal muscle cells by downregulation of glycogen synthase protein expression

Metabolism ◽

10.1053/meta.2000.7717 ◽

2000 ◽

Vol 49 (8) ◽

pp. 962-968 ◽

Cited By ~ 8

Author(s):

K.S. Park ◽

T.P. Ciaraldi ◽

L. Carter ◽

S. Mudaliar ◽

S.E. Nikoulina ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Protein Expression ◽

Human Skeletal Muscle ◽

Glycogen Synthase ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Human Skeletal Muscle Cells

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RNA-sequencing analysis reveals the potential contribution of lncRNAs in palmitic acid-induced insulin resistance of skeletal muscle cells

Bioscience Reports ◽

10.1042/bsr20192523 ◽

2020 ◽

Vol 40 (1) ◽

Cited By ~ 1

Author(s):

Mei Han ◽

Lianghui You ◽

Yanting Wu ◽

Nan Gu ◽

Yan Wang ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Palmitic Acid ◽

Signaling Pathway ◽

Rna Sequencing ◽

Metabolic Diseases ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

C2c12 Myotubes ◽

Insulin Resistant

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| > 2, q < 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.

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Metformin Increases Protein Phosphatase 2A Activity in Primary Human Skeletal Muscle Cells Derived from Lean Healthy Participants

Journal of Diabetes Research ◽

10.1155/2021/9979234 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Aktham Mestareehi ◽

Xiangmin Zhang ◽

Berhane Seyoum ◽

Zaher Msallaty ◽

Abdullah Mallisho ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Sensitivity ◽

Protein Phosphatase ◽

Human Skeletal Muscle ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Human Skeletal Muscle Cells ◽

Phosphatase 2A ◽

Sensitivity Improvement

Context. Skeletal muscle insulin resistance is one of the primary contributors of type 2 diabetes (T2D). Metformin is the first-line drug for the treatment of T2D. The primary effects of metformin include decreasing glucose production in the liver and decreasing insulin resistance in the skeletal muscle. However, the molecular mechanism of metformin’s action in skeletal muscle is not well understood. Protein phosphatase 2A (PP2A), a major serine/threonine protein phosphatase, plays a pivotal role in cellular processes, such as signal transduction, cell proliferation, and apoptosis, and acts through dephosphorylating key signaling molecules such as AKT and AMPK. However, whether PP2A plays a role in metformin-induced insulin sensitivity improvement in human skeletal muscle cells remains to be elucidated. Objective. To investigate if PP2A plays a role in metformin-induced insulin sensitivity improvement in human skeletal muscle cells. Participants. Eight lean insulin-sensitive nondiabetic participants (4 females and 4 males; age: 21.0 ± 1.0 years; BMI: 22.0 ± 0.7 kg / m 2 ; 2-hour OGTT: 97.0 ± 6.0 mg / dl ; HbA1c: 5.3 ± 0.1 % ; fasting plasma glucose: 87.0 ± 2.0 mg / dl ; M value; 11.0 ± 1.0 mg / kgBW / min ). Design. A hyperinsulinemic-euglycemic clamp was performed to assess insulin sensitivity in human subjects, and skeletal muscle biopsy samples were obtained. Primary human skeletal muscle cells (shown to retain metabolic characteristics of donors) were cultured from these muscle biopsies that included 8 lean insulin-sensitive participants. Cultured cells were expanded, differentiated into myotubes, and treated with 50 μM metformin for 24 hours before harvesting. PP2Ac activity was measured by a phosphatase activity assay kit (Millipore) according to the manufacturer’s protocol. Results. The results indicated that metformin significantly increased the activity of PP2A in the myotubes for all 8 lean insulin-sensitive nondiabetic participants, and the average fold increase is 1.54 ± 0.11 ( P < 0.001 ). Conclusions. These results provided the first evidence that metformin can activate PP2A in human skeletal muscle cells derived from lean healthy insulin-sensitive participants and may help to understand metformin’s action in skeletal muscle in humans.

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