Mitochondrial dysfunction enhances the migration of vascular smooth muscles cells via suppression of Akt phosphorylation |
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Authors: | Sun Young Ahn Yon-Sik ChoiHyun-Jung Koo Jae Hoon JeongWook Ha Park Minseok KimYing Piao Youngmi Kim Pak |
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Institution: | Age-Related and Brain Diseases Research Center, Department of Nanopharmaceutical and Life Sciences, Department of Physiology, Kyung Hee University College of Medicine, Dongdaemoon-Gu Hoegi-Dong #1, Seoul 130-701, Korea |
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Abstract: | BackgroundAtherosclerosis is one of the major complications of diabetes, which may result from insulin resistance via mitochondrial dysfunction. Although a strong association between insulin resistance and cardiovascular disease has been suggested, it is not clear yet whether stress-inducing factors damage mitochondria and insulin signaling pathway in cardiovascular tissues.MethodsWe investigated whether stress-induced mitochondrial dysfunction might alter the insulin/Akt signaling pathway in A10 rat vascular smooth muscle cells (VSMC).ResultsThe treatment of oxidized low density lipoprotein (oxLDL) decreased ATP contents, mitochondrial respiration activity, mRNA expressions of OXPHOS subunits and IRS-1/2 and insulin-mediated phosphorylations of Akt and AMP-activated protein kinase (AMPK). Similarly, dideoxycytidine (ddC), the mtDNA replication inhibitor, or rotenone, OXPHOS complex I inhibitor, inhibited the insulin-mediated pAkt while increased pAMPK regardless of insulin. Reciprocally, an inhibitor of Akt, triciribine (TCN), decreased cellular ATP contents. Overexpression of Akt dominant positive reversed the oxLDL- or ddC-mediated ATP decrease but AMPK activator did not. Akt activation also normalized the aberrant VSMC migration induced by ddC.ConclusionsDefective insulin signaling and mitochondrial function may collectively contribute to developing cardiovascular disease.General significanceAkt may be a possible therapeutic target for treating insulin resistance-associated atherosclerosis. |
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Keywords: | VSMC vascular smooth muscle cells oxLDL oxidized low density lipoprotein ddC dideoxycytidine OXPHOS oxidative phosphorylation AMPK AMP-activated protein kinase TCN triciribine AICAR aminoimidazole carboxamide ribonucleotide OCR oxygen consumption rate SFM serum free media |
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