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Protein Tyrosine Phosphatase Type 1B (PTP1B) Contributes To Atherosclerotic Processes By Mechanisms That Involve NADPH‐Oxidase And Calcium Influx
Author(s) -
da Silva Josiane Fernandes,
Alves Juliano Vilela,
Bolsonni Juliana A.,
Costa Rafael M.,
Rios Francisco J.,
Camargo Livia L.,
Montezano Augusto C.,
Touyz Rhian M.,
Tostes Rita C.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.03682
Subject(s) - medicine , endocrinology , nadph oxidase , chemistry , vasoprotective , endothelial dysfunction , protein tyrosine phosphatase , nitric oxide , biology , oxidative stress , receptor
PTP1B is a protein tyrosine phosphatase (PTP) widely expressed in different cell type including vascular smooth muscle and endothelial cells. PTP1B activation is linked to downregulation of insulin signalling, impairment of nitric oxide production, induction of endoplasmic reticulum stress and angiogenesis. While inhibition of PTP1B decreases atherosclerotic plaque size and increases systemic levels of interleukin 10 (IL‐10), effects on vascular function are unclear. This study tested the hypothesis that PTP1B inhibition attenuates atherosclerosis‐associated vascular dysfunction by reducing endothelial ROS production. Methods Male 12 week‐old apolipoprotein E knockout (apoEKO) and wild type (WT) mice were fed a control diet or a high fat (HF) diet (15% cocoa butter; 0.5% cholesterol; 10% protein; 25% carbohydrate; 65% fat; 9,6 kcal/g) for 8 weeks. Animals were treated with the PTP1B inhibitor claramine, 2 mg/Kg/week, i.p., for 3 weeks. Glucose, cholesterol, low density lipoprotein (LDL) and triglycerides (TG) were measured. In vitro studies were performed in human aortic endothelial cells (HAEC) stimulated with lysophosphatidicholine (10 −5 M). ROS production was evaluated by lucigenin and DHE fluorescence. Aortic reactivity was evaluated using isometric transducer myograph. Global PTP irreversible oxidation was determined by immunoprecipitation and western blot. PTP, VCAM, NOX4, NOX5 mRNA expression was determined by qPCR. Phosphorylated protein levels, PTP activity, ROS production and calcium influx were evaluated in stimulated HAECs ± PTP1b inhibitor or vehicle. Experiments were approved by the Ethics Committee on Animal Research of the Ribeirao Preto Medical School, University of Sao Paulo (protocol n°106/2019). Results ApoEKO mice showed dyslipidaemia, characterized by increased serum levels of cholesterol (WT = 154.7 ± 2.8 vs . apoEKO = 1668.0 ± 26.7 mg/dL) and LDL (WT = 86.5 ± 1.4 vs . apoEKO = 976.2 ± 17.8 mg/dL). Aortic arch and carotid artery atherosclerotic plaque areas showed higher PTP1B, NOX4 and VCAM gene expression than control areas (p < 0.05). Vasorelaxation to acetylcholine was decreased in apoEKO mice vs . WT mice. Claramine restored this response. In HAECs, LPC stimulated ROS generation by NOX5‐dependent mechanisms. LPC also induced PTP1B expression and activation. PTP1B inhibition in HAECs reduced ROS production and normalized NO production and intracellular calcium responses. Conclusion PTP1B contributes to endothelial dysfunction by mechanisms that involve ROS production. PTP1B inhibition may be targeted to reduce vascular injury in atherosclerosis. Support or Funding Information FAPESP