20 research outputs found

    Two new species of the side necked turtle genus, Bairdemys (Pleurodira, Podocnemididae), from the Miocene of Venezuela

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    The side-necked turtle genusBairdemys (Podocnemididae,Shweboemys Group) from the Miocene of Venezuela and Puerto Rico is revised, and four species are diagnosed on the basis of skull characters; two are de-scribed as new.B. hartsteini Gaffney & Wood, 2002, from the Cibao Formation of Puerto Rico, is characterized by a higher skull, with a straight labial ridge and a premaxillary notch;B. venezuelensis (Wood & Díaz de Gamero 1971), from the Urumaco Formation of Venezuela, is characterized by the absence of a premaxillary notch, a high anterior triturating surface convexity, a deep posterior triturating surface concavity, and a short pterygoid mid-line contact;B. sanchezi, new species, from the Urumaco Formation of Venezuela, is characterized by a very low anterior triturating surface convexity and shallow posterior triturating surface concavity, a premaxillary notch, small size, and extensive temporal and cheek emargination;B. winklerae, new species, from the Urumaco Formation of Venezuela, is characterized by an elongate, narrow snout, with a concave labial ridge, and no premaxillary notch. Based on osteological and bone histological results, an additional strongly crushed skull and associated cara-pace fragment of a previously undetermined podocnemidid from the Urumaco Formation of Venezuela can be further referred toPodocnemis or a closely related taxon — again underscoring the importance of this formation as one of the major fossil lagerstätten of turtles in South America

    PCSK6 Is a Key Protease in the Control of Smooth Muscle Cell Function in Vascular Remodeling

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    Rationale: Proprotein convertase subtilisins/kexins (PCSKs) 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 (ECM) 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 vs. healthy arteries, using transcriptomic and proteomic datasets. By immunohistochemistry, PCSK6 was localised 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 and MMP2/MMP14. Here, PCSK6 was shown to co-localise and co-interact with MMP2/MMP14 by in situ proximity ligation assay. Microarrays of carotid arteries from Pcsk6-/- vs. control mice revealed suppression of contractile SMC markers, ECM 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 lead to downregulation of contractile markers and increase in MMP2 expression. Conversely, PCSK6 overexpression increased PDGFBB-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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