Myocardial Infarction-Associated SNP at 6p24 Interferes With MEF2 Binding and Associates With PHACTR1 Expression Levels in Human Coronary Arteries.

OBJECTIVE: Coronary artery disease (CAD), including myocardial infarction (MI), is the main cause of death in the world. Genome-wide association studies have identified dozens of single nucleotide polymorphisms (SNPs) associated with CAD/MI. One of the most robust CAD/MI genetic associations is with intronic SNPs in the gene PHACTR1 on chromosome 6p24. How these PHACTR1 SNPs influence CAD/MI risk, and whether PHACTR1 itself is the causal gene at the locus, is currently unknown. APPROACH AND RESULTS: Using genetic fine-mapping and DNA resequencing experiments, we prioritized an intronic SNP (rs9349379) in PHACTR1 as causal variant. We showed that this variant is an expression quantitative trait locus for PHACTR1 expression in human coronary arteries. Experiments in endothelial cell extracts confirmed that alleles at rs9349379 are differentially bound by the transcription factors myocyte enhancer factor-2. We engineered a deletion of this myocyte enhancer factor-2-binding site using CRISPR/Cas9 genome-editing methodology. Heterozygous endothelial cells carrying this deletion express 35% less PHACTR1. Finally, we found no evidence that PHACTR1 expression levels are induced when stimulating human endothelial cells with vascular endothelial growth factor, tumor necrosis factor-α, or shear stress. CONCLUSIONS: Our results establish a link between intronic SNPs in PHACTR1, myocyte enhancer factor-2 binding, and transcriptional functions at the locus, PHACTR1 expression levels in coronary arteries and CAD/MI risk. Because PHACTR1 SNPs are not associated with the traditional risk factors for CAD/MI (eg, blood lipids or pressure, diabetes mellitus), our results suggest that PHACTR1 may influence CAD/MI risk through as yet unknown mechanisms in the vascular endothelium.

Tyrosine phosphorylation of DEP-1/CD148 as a mechanism controlling Src kinase activation, endothelial cell permeability, invasion, and capillary formation.

DEP-1/CD148 is a receptor-like protein tyrosine phosphatase with antiproliferative and tumor-suppressive functions. Interestingly, it also positively regulates Src family kinases in hematopoietic and endothelial cells, where we showed it promotes VE-cadherin-associated Src activation and endothelial cell survival upon VEGF stimulation. However, the molecular mechanism involved and its biologic functions in endothelial cells remain ill-defined. We demonstrate here that DEP-1 is phosphorylated in a Src- and Fyn-dependent manner on Y1311 and Y1320, which bind the Src SH2 domain. This allows DEP-1-catalyzed dephosphorylation of Src inhibitory Y529 and favors the VEGF-induced phosphorylation of Src substrates VE-cadherin and Cortactin. Accordingly, RNA interference (RNAi)-mediated knockdown of DEP-1 or expression of DEP-1 Y1311F/Y1320F impairs Src-dependent biologic responses mediated by VEGF including permeability, invasion, and branching capillary formation. In addition, our work further reveals that above a threshold expression level, DEP-1 can also dephosphorylate Src Y418 and attenuate downstream signaling and biologic responses, consistent with the quiescent behavior of confluent endothelial cells that express the highest levels of endogenous DEP-1. Collectively, our findings identify the VEGF-dependent phosphorylation of DEP-1 as a novel mechanism controlling Src activation, and show this is essential for the proper regulation of permeability and the promotion of the angiogenic response.

Respecter les normes et posséder un sens du spectacle en communication orale en sciences: les deux aspects du sentiment d'efficacité personnelle d'étudiants postsecondaires en sciences.

Proficiency in oral communication is an important skill to develop in science. Central to its development is self-efficacy. In this study we examine two aspects of self-efficacy: first, standards and content, and second, showmanship. We looked at these aspects among students enrolled in a natural sciences program at the Quebec collège level (a two-year post-secondary program in which students are usually between the ages of 17 and 19) in relation to their experiences of oral communication on scientific subjects. A sample of students responded to a questionnaire developed as part of this study on perceptions and attitudes towards communicating orally in the sciences (PACOS), first at the start of their program (n = 1292) and then at the end (n = 179). A subsample of this group (n = 26) also participated in an interview for deeper analysis. The results, coupled with those from a previous study, show that the two aforementioned aspects of self-efficacy are distinct but complementary. Moreover, we observed that they are linked to other subcomponents of one's attitude towards scientific oral communication-namely anxiety, pleasure, perception of relevance, and context. Finally, we noted that the standards and content aspect of self-efficacy remained consistent over time, while the sense of showmanship increased among participants between the start and end of their studies.

L'habileté à communiquer à l'oral est une compétence importante à développer en science. Central au développement de celle-ci, le sentiment d'efficacité personnelle (SEP) est étudié dans cette recherche en accord avec les deux aspects qui le composent, soit le SEP normes et contenus et le SEP sens du spectacle. Ces deux aspects du SEP ont été étudiés chez des étudiants du programme collégial québécois de Sciences de la nature (programme post-secondaire de 2 ans, entre 17 et 19 ans habituellement), en lien avec leurs expériences en communication orale sur des sujets scientifiques. Un échantillon d'étudiants de ce programme a répondu au questionnaire PACOS (Perceptions et attitude en communication orale en sciences) développé dans le cadre de cette recherche, d'abord au début de leurs études collégiales (n = 1 292), puis à la fin (n = 179). Un sous-échantillon d'entre eux (n = 26) a de plus participé à un entretien d'approfondissement. Les résultats, couplés à ceux d'une étude antérieure, montrent que les deux aspects du SEP sont bien distincts, mais complémentaires. En outre, nous avons observé que les deux aspects du SEP sont reliés aux autres sous-composantes de l'attitude envers la communication orale scientifique, nommément l'anxiété, le plaisir, la perception de la pertinence et la dépendance au contexte. Finalement, nous avons noté que le SEP normes et contenu semblait stable dans le temps, tandis que le SEP sens du spectacle avait augmenté entre le début et la fin des études collégiales chez nos participants.

Phosphorylation of DEP-1/PTPRJ on threonine 1318 regulates Src activation and endothelial cell permeability induced by vascular endothelial growth factor.

The protein tyrosine phosphatase DEP-1/PTPRJ positively regulates Src family kinases and critical biological functions in endothelial and hematopoietic cells. Phosphorylation of DEP-1 on Y1311/Y1320 mediates the association and activation of Src, and promotes Src-dependent angiogenic responses including endothelial cell permeability. We have identified T1318 as a phosphorylated residue proximal to Y1320. The aim of this study was to determine if T1318 phosphorylation exerts a regulatory role over the function of DEP-1. We show that phosphorylation of DEP-1 on Y1320 was reduced when T1318 was mutated. This led to the decreased association of DEP-1 T1318A with Src, and defective Src activation in both HEK 293T and VEGF-stimulated endothelial cells. Consistent with these findings, VEGF-induced tyrosine phosphorylation of VE-cadherin, its association to ß-arrestin1/2, and cell permeability were impaired in cells expressing DEP-1 T1318A. Conversely, expression of the phosphomimetic mutant DEP-1 T1318E constitutively enhanced the phosphorylation of Y1320 and VE-cadherin over that induced by WT DEP-1, and resulted in increased VEGF-dependent permeability. DEP-1 T1318 is part of a CK2 consensus phosphorylation site and was identified as a CK2 substrate. Modulation of CK2 expression or activity in endothelial cells regulated T1318 phosphorylation, and correlated with the status of Y1320 phosphorylation, Src activation, and cell permeability. CK2-dependent phosphorylation of DEP-1 T1318 promotes Y1320 phosphorylation and Src activation upon VEGF stimulation. Phosphorylation of T1318 is thus part of a regulatory mechanism that channels the activity of DEP-1 towards Src to allow its optimal activation and the promotion of endothelial cell permeability.