Person:

Singh, Sasha

Calcifying extracellular vesicles (EVs) released from cells within atherosclerotic plaques have received increased attention for their role in mediating vascular calcification, a major predictor of cardiovascular morbidity and mortality. However, little is known about the difference between this pathologic vesicle population and other EVs that contribute to physiological cellular processes. One major challenge that hinders research into these differences is the inability to selectively isolate calcifying EVs from other vesicle populations. In this study, we hypothesized that the formation of mineral within calcifying EVs would increase the density of the vesicles such that they would pellet at a faster rate during ultracentrifugation. We show that after 10 min of ultracentrifugation at 100,000×g, calcifying EVs are depleted from the conditioned media of calcifying coronary artery smooth muscle cells and are enriched in the pelleted portion. We utilized mass spectrometry to establish functional proteomic differences between the calcifying EVs enriched in the 10 min ultracentrifugation compared to other vesicle populations preferentially pelleted by longer ultracentrifugation times. The procedures established in this study will allow us to enrich the vesicle population of interest and perform advanced proteomic analyses to find subtle differences between calcifying EVs and other vesicle populations that may be translated into therapeutic targets for vascular calcification. Finally, we will show that the differences in ultracentrifugation times required to pellet the vesicle populations can also be used to estimate physical differences between the vesicles.

Despite the global impact of macrophage activation in vascular disease, the underlying mechanisms remain obscure. Here we show, with global proteomic analysis of macrophage cell lines treated with either IFNγ or IL-4, that PARP9 and PARP14 regulate macrophage activation. In primary macrophages, PARP9 and PARP14 have opposing roles in macrophage activation. PARP14 silencing induces pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells, whereas it suppresses anti-inflammatory gene expression and STAT6 phosphorylation in M(IL-4) cells. PARP9 silencing suppresses pro-inflammatory genes and STAT1 phosphorylation in M(IFNγ) cells. PARP14 induces ADP-ribosylation of STAT1, which is suppressed by PARP9. Mutations at these ADP-ribosylation sites lead to increased phosphorylation. Network analysis links PARP9–PARP14 with human coronary artery disease. PARP14 deficiency in haematopoietic cells accelerates the development and inflammatory burden of acute and chronic arterial lesions in mice. These findings suggest that PARP9 and PARP14 cross-regulate macrophage activation.