Person:

Cloutier, Jennifer

Summary Vascular endothelium is a dynamic cellular interface that displays a unique phenotypic plasticity. This plasticity is critical for vascular function and when dysregulated is pathogenic in several diseases. Human genotype-phenotype studies of endothelium are limited by the unavailability of patient-specific endothelial cells. To establish a cellular platform for studying endothelial biology, we have generated vascular endothelium from human induced pluripotent stem cells (iPSCs) exhibiting the rich functional phenotypic plasticity of mature primary vascular endothelium. These endothelial cells respond to diverse proinflammatory stimuli, adopting an activated phenotype including leukocyte adhesion molecule expression, cytokine production, and support for leukocyte transmigration. They maintain dynamic barrier properties responsive to multiple vascular permeability factors. Importantly, biomechanical or pharmacological stimuli can induce pathophysiologically relevant atheroprotective or atheroprone phenotypes. Our results demonstrate that iPSC-derived endothelium possesses a repertoire of functional phenotypic plasticity and is amenable to cell-based assays probing endothelial contributions to inflammatory and cardiovascular diseases.

PHF8 is a histone demethylase with specificity for repressive modifications. While mutations of PHF8 have been associated with cognitive defects and cleft lip/palate, its role in mammalian development and physiology remains unexplored. Here, we have generated a Phf8 knockout allele in mice to examine the consequences of Phf8 loss for development and behaviour. Phf8 deficient mice neither display obvious developmental defects nor signs of cognitive impairment. However, we report a striking resiliency to stress-induced anxiety- and depression-like behaviour on loss of Phf8. We further observe misregulation of serotonin signalling within the prefrontal cortex of Phf8 deficient mice and identify the serotonin receptors Htr1a and Htr2a as direct targets of PHF8. Our results clarify the functional role of Phf8 in mammalian development and behaviour and establish a direct link between Phf8 expression and serotonin signalling, identifying this histone demethylase as a potential target for the treatment of anxiety and depression.