PPP2R5B, a regulatory subunit of PP2A, contributes to adipocyte insulin resistance
| Autor: | Durgesh Kumar, Kripa Shankar, Sujith Rajan, Abhishek Gupta, Ankita Srivastava, Anil N. Gaikwad, Muheeb Beg, Salil Varshney |
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| Rok vydání: | 2016 |
| Předmět: |
Male
0301 basic medicine medicine.medical_specialty Glucose uptake medicine.medical_treatment Down-Regulation Diet High-Fat Biochemistry Mice 03 medical and health sciences 0302 clinical medicine Endocrinology Insulin resistance Downregulation and upregulation 3T3-L1 Cells Internal medicine Insulin receptor substrate Adipocytes medicine Animals Humans Insulin Protein Phosphatase 2 Enzyme Inhibitors Promoter Regions Genetic Molecular Biology Protein kinase B biology Lentivirus Biological Transport Alkaline Phosphatase medicine.disease Up-Regulation Enzyme Activation Mice Inbred C57BL Disease Models Animal Protein Subunits Insulin receptor Glucose HEK293 Cells 030104 developmental biology 030220 oncology & carcinogenesis biology.protein Insulin Resistance GLUT4 Signal Transduction |
| Zdroj: | Molecular and Cellular Endocrinology. 437:97-107 |
| ISSN: | 0303-7207 |
| Popis: | Insulin resistance is associated with deregulation of insulin signaling owing to the chronic exposure of insulin (hyperinsulinemia) to the tissues. Phosphorylation and dephosphorylation events in insulin signaling pathway play an essential role in signal transduction and glucose uptake. Amongst all, Akt protein is considered to be central to the overall insulin signaling proteins. In glucose responsive tissues like adipose and muscles, activation of Akt is responsible for triggering GLUT4 translocation and glucose transport. Several phosphatases such as PTEN, PP2A have been reported to be involved in dephosphorylation and inactivation of Akt protein. We have identified increased PP2A activity during state of chronic hyperinsulinemia exposure along-with development of adipocyte insulin resistance. This increased phosphatase activity leads activation of cAMP/PKA axis, which in turn increased cAMP levels in insulin resistant (IR) adipocytes. Okadaic acid, an inhibitor of PP2A restored and increased insulin stimulated glucose uptake in insulin resistant (IR) and insulin sensitive (IS) adipocytes respectively. In IS adipocyte, chemical activation of PP2A through MG132 and FTY720 showed decreased insulin sensitivity corroborated with decreased Akt phosphorylation and glucose uptake. We also observed an increased expression of PP2A-B (regulatory) subunit in IR adipocytes. We found PPP2R5B, a regulatory subunit of PP2A is responsible for the dephosphorylation and inactivation of Akt protein. Increased expression of PPP2R5B was also confirmed in white adipose tissue of high fat diet induced IR mice model. Overexpression and suppression strategies confirmed the role of PPP2R5B in regulating insulin signaling. Thus, we conclude that PPP2R5B, a B subunit of PP2A is a negative regulator of Akt phosphorylation contributing partly to the chronic hyperinsulinemia induced insulin resistance in adipocytes. |
| Databáze: | OpenAIRE |
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