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- Rykaczewska, Urszula, et al.
(författare)
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PCSK6 Is a Key Protease in the Control of Smooth Muscle Cell Function in Vascular Remodeling
- 2020
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Ingår i: Circulation Research. - : LIPPINCOTT WILLIAMS & WILKINS. - 0009-7330 .- 1524-4571. ; 126:5, s. 571-585
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: PCSKs (Proprotein convertase subtilisins/kexins) are a protease family with unknown functions in vasculature. Previously, we demonstrated PCSK6 upregulation in human atherosclerotic plaques associated with smooth muscle cells (SMCs), inflammation, extracellular matrix remodeling, and mitogens. Objective: Here, we applied a systems biology approach to gain deeper insights into the PCSK6 role in normal and diseased vessel wall. Methods and Results: Genetic analyses revealed association of intronic PCSK6 variant rs1531817 with maximum internal carotid intima-media thickness progression in high-cardiovascular risk subjects. This variant was linked with PCSK6 mRNA expression in healthy aortas and plaques but also with overall plaque SMA+ cell content and pericyte fraction. Increased PCSK6 expression was found in several independent human cohorts comparing atherosclerotic lesions versus healthy arteries, using transcriptomic and proteomic datasets. By immunohistochemistry, PCSK6 was localized to fibrous cap SMA+ cells and neovessels in plaques. In human, rat, and mouse intimal hyperplasia, PCSK6 was expressed by proliferating SMA+ cells and upregulated after 5 days in rat carotid balloon injury model, with positive correlation to PDGFB (platelet-derived growth factor subunit B) and MMP (matrix metalloprotease) 2/MMP14. Here, PCSK6 was shown to colocalize and cointeract with MMP2/MMP14 by in situ proximity ligation assay. Microarrays of carotid arteries from Pcsk6(-/-) versus control mice revealed suppression of contractile SMC markers, extracellular matrix remodeling enzymes, and cytokines/receptors. Pcsk6(-/-) mice showed reduced intimal hyperplasia response upon carotid ligation in vivo, accompanied by decreased MMP14 activation and impaired SMC outgrowth from aortic rings ex vivo. PCSK6 silencing in human SMCs in vitro leads to downregulation of contractile markers and increase in MMP2 expression. Conversely, PCSK6 overexpression increased PDGFBB (platelet-derived growth factor BB)-induced cell proliferation and particularly migration. Conclusions: PCSK6 is a novel protease that induces SMC migration in response to PDGFB, mechanistically via modulation of contractile markers and MMP14 activation. This study establishes PCSK6 as a key regulator of SMC function in vascular remodeling.
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| 2. |
- Vignon, É., et al.
(författare)
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Challenging and Improving the Simulation of Mid-Level Mixed-Phase Clouds Over the High-Latitude Southern Ocean
- 2021
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 126:7
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Tidskriftsartikel (refereegranskat)abstract
- Climate models exhibit major radiative biases over the Southern Ocean owing to a poor representation of mixed-phase clouds. This study uses the remote-sensing dataset from the Measurements of Aerosols, Radiation and Clouds over the Southern Ocean (MARCUS) campaign to assess the ability of the Weather Research and Forecasting (WRF) model to reproduce frontal clouds off Antarctica. It focuses on the modeling of thin mid-level supercooled liquid water layers which precipitate ice. The standard version of WRF produces almost fully glaciated clouds and cannot reproduce cloud top turbulence. Our work demonstrates the importance of adapting the ice nucleation parameterization to the pristine austral atmosphere to reproduce the supercooled liquid layers. Once simulated, droplets significantly impact the cloud radiative effect by increasing downwelling longwave fluxes and decreasing downwelling shortwave fluxes at the surface. The net radiative effect is a warming of snow and ice covered surfaces and a cooling of the ocean. Despite improvements in our simulations, the local turbulent circulation related to cloud-top radiative cooling is not properly reproduced, advocating for the need to develop a parameterization for top-down convection to capture the turbulence-microphysics interplay at cloud top. Plain Language Summary Among the major shortcomings of climate models is a poor representation of clouds over the Southern Ocean. Thanks to new measurements from the Measurements of Aerosols, Radiation and Clouds over the Southern Ocean campaign that took place aboard the Aurora Australia ice breaker, we can now better assess the ability of models to represent clouds off Antarctica. In particular, we focus here on clouds that are mostly composed of ice crystals but that are topped by a thin layer of so-called supercooled liquid droplets that form at temperatures below zero Celsius. While the standard version of the model produces clouds composed only of ice, we show that by adapting the formulation of ice crystal formation to the very pristine atmospheric conditions peculiar to the Southern Ocean it is possible to successfully reproduce thin layers of supercooled liquid droplets observed in mixed-phase clouds. The latter significantly changes how much sunlight these clouds reflect to space, which is critical to understanding the climate. Compared to ice crystals, liquid droplets tend to reflect more solar energy toward space and at the same time, they enhance the cloud infrared emission toward the surface of the Antarctic ice sheet.
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