Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase.
Insulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains...
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Public Library of Science (PLoS)
2013-01-01
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| Series: | PLoS ONE |
| Online Access: | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0056928&type=printable |
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| author | Antonio J Ruiz-Alcaraz Christopher Lipina John R Petrie Michael J Murphy Andrew D Morris Calum Sutherland Daniel J Cuthbertson |
| author_facet | Antonio J Ruiz-Alcaraz Christopher Lipina John R Petrie Michael J Murphy Andrew D Morris Calum Sutherland Daniel J Cuthbertson |
| author_sort | Antonio J Ruiz-Alcaraz |
| collection | DOAJ |
| description | Insulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains controversial; reduced post-receptor signalling of the insulin receptor substrate 1 (IRS1) adaptor protein and downstream effectors such as protein kinase B (PKB) have previously been implicated. We examined expression and/or activation of a number of components of the insulin-signalling cascade in skeletal muscle of 22 healthy young men (with body mass index (BMI) range, 20-37 kg/m(2)). Whole body insulin sensitivity (M value) and body composition was determined by the hyperinsulinaemic (40 mU. min(-1).m(-2).), euglycaemic clamp and by dual energy X-ray absorptiometry (DEXA) respectively. Skeletal muscle (vastus lateralis) biopsies were taken before and after one hour of hyperinsulinaemia and the muscle insulin signalling proteins examined by western blot and immunoprecipitation assay. There was a strong inverse relationship between M-value and BMI. The most striking abnormality was significantly reduced insulin-induced activation of p42/44 MAP kinase, measured by specific assay, in the volunteers with poor insulin sensitivity. However, there was no relationship between individuals' BMI or M-value and protein expression/phosphorylation of IRS1, PKB, or p42/44 MAP kinase protein, under basal or hyperinsulinaemic conditions. In the few individuals with poor insulin sensitivity but preserved p42/44 MAP kinase activation, other signalling defects were evident. These findings implicate defective p42/44 MAP kinase signalling as a potential contributor to obesity-related IR in a non-diabetic population, although clearly multiple signalling defects underlie obesity associated IR. |
| format | Article |
| id | doaj-art-dbbdf793106c47e1a744e9a25b32b590 |
| institution | Kabale University |
| issn | 1932-6203 |
| language | English |
| publishDate | 2013-01-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS ONE |
| spelling | doaj-art-dbbdf793106c47e1a744e9a25b32b5902025-08-20T03:26:47ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-0182e5692810.1371/journal.pone.0056928Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase.Antonio J Ruiz-AlcarazChristopher LipinaJohn R PetrieMichael J MurphyAndrew D MorrisCalum SutherlandDaniel J CuthbertsonInsulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains controversial; reduced post-receptor signalling of the insulin receptor substrate 1 (IRS1) adaptor protein and downstream effectors such as protein kinase B (PKB) have previously been implicated. We examined expression and/or activation of a number of components of the insulin-signalling cascade in skeletal muscle of 22 healthy young men (with body mass index (BMI) range, 20-37 kg/m(2)). Whole body insulin sensitivity (M value) and body composition was determined by the hyperinsulinaemic (40 mU. min(-1).m(-2).), euglycaemic clamp and by dual energy X-ray absorptiometry (DEXA) respectively. Skeletal muscle (vastus lateralis) biopsies were taken before and after one hour of hyperinsulinaemia and the muscle insulin signalling proteins examined by western blot and immunoprecipitation assay. There was a strong inverse relationship between M-value and BMI. The most striking abnormality was significantly reduced insulin-induced activation of p42/44 MAP kinase, measured by specific assay, in the volunteers with poor insulin sensitivity. However, there was no relationship between individuals' BMI or M-value and protein expression/phosphorylation of IRS1, PKB, or p42/44 MAP kinase protein, under basal or hyperinsulinaemic conditions. In the few individuals with poor insulin sensitivity but preserved p42/44 MAP kinase activation, other signalling defects were evident. These findings implicate defective p42/44 MAP kinase signalling as a potential contributor to obesity-related IR in a non-diabetic population, although clearly multiple signalling defects underlie obesity associated IR.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0056928&type=printable |
| spellingShingle | Antonio J Ruiz-Alcaraz Christopher Lipina John R Petrie Michael J Murphy Andrew D Morris Calum Sutherland Daniel J Cuthbertson Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. PLoS ONE |
| title | Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. |
| title_full | Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. |
| title_fullStr | Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. |
| title_full_unstemmed | Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. |
| title_short | Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase. |
| title_sort | obesity induced insulin resistance in human skeletal muscle is characterised by defective activation of p42 p44 map kinase |
| url | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0056928&type=printable |
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