Abstract
The kinase AKT2 (PKB) is an important mediator of insulin signaling, for which loss-of-function knockout (KO) mutants lead to early onset diabetes mellitus, and dominant active mutations lead to early development of obesity and endothelial cell (EC) dysfunction. To model EC dysfunction, we used edited human pluripotent stem cells (hPSCs) that carried either a homozygous deletion of AKT2 (AKT2 KO) or a dominant active mutation (AKT2 E17K), which, along with the parental wild type (WT), were differentiated into ECs. Profiling of EC lines indicated an increase in proinflammatory and a reduction in anti-inflammatory fatty acids, an increase in inflammatory chemokines in cell supernatants, increased expression of proinflammatory genes, and increased binding to the EC monolayer in a functional leukocyte adhesion assay for both AKT2 KO and AKT2 E17K. Collectively, these findings suggest that vascular endothelial inflammation that results from dysregulated insulin signaling (homeostasis) may contribute to coronary artery disease, and that either downregulation or upregulation of the insulin pathway may lead to inflammation of endothelial cells. This suggests that the standard of care for patients must be expanded from control of metabolic parameters to include control of inflammation, such that endothelial dysfunction and cardiovascular disorders can ultimately be prevented.
Highlights
In human tissues, insulin sensitivity is regulated through the activation of the serine/threonine kinase AKT2 (PKB beta)
A comparison of metabolic rates suggested a tendency for increased catabolism of ATP and ADP (Figure 1C) and of glucose-6-P and glycerol in AKT2 E17K cells compared with WT (Figure S2A)
Pluripotent stem cell technology offers the possibility of generating every cell type in the human body and, along with genome editing, has the potential to model each and every genetic disease
Summary
Insulin sensitivity is regulated through the activation of the serine/threonine kinase AKT2 (PKB beta). A loss-of-function mutation in the AKT2 gene is the cause of a subtype of the rare disease familial partial lipodystrophy that results in severe insulin resistance and leads to early onset diabetes mellitus with lipodystrophy and hyperinsulinemia [1]. Patients that carry a partial loss-of-function variant of AKT2 tend to have a higher level of fasting plasma insulin and an increased risk of developing diabetes mellitus [2]. We focused on the effects of these AKT2 mutations on endothelial cells (ECs). ECs are an important target of insulin [6,7], and the primary effect of insulin is to activate the kinase AKT1, which leads to phosphorylation of eNOS and vasodilatation to increase nutrient delivery to tissues [8]. The specific function of the closely related kinase AKT2 in endothelial cells has not been studied
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