The mitochondrial protease ClpP is a druggable target that controls VSMC phenotype by a SIRT1-dependent mechanism.

Vascular smooth muscle cells (VSMCs), known for their remarkable lifelong phenotypic plasticity, play a pivotal role in vascular pathologies through their ability to transition between different phenotypes. Our group discovered that the deficiency of the mitochondrial protein Poldip2 induces VSMC differentiation both in vivo and in vitro. Further comprehensive biochemical investigations revealed Poldip2's specific interaction with the mitochondrial ATPase caseinolytic protease chaperone subunit X (CLPX), which is the regulatory subunit for the caseinolytic protease proteolytic subunit (ClpP) that forms part of the ClpXP complex - a proteasome-like protease evolutionarily conserved from bacteria to humans.

The Role of Fatty Acid Synthase in the Vascular Smooth Muscle Cell to Foam Cell Transition.

Vascular smooth muscle cells (VSMCs), in their contractile and differentiated state, are fundamental for maintaining vascular function. Upon exposure to cholesterol (CHO), VSMCs undergo dedifferentiation, adopting characteristics of foam cells-lipid-laden, macrophage-like cells pivotal in atherosclerotic plaque formation. CHO uptake by VSMCs leads to two primary pathways: ABCA1-mediated efflux or storage in lipid droplets as cholesterol esters (CEs).

Antibacterial activity, cytocompatibility, and thermomechanical stability of TiZrCuPd bulk metallic glass.

This paper envisions TiZrCuPd bulk metallic glass as an oral implant material and evaluates its antibacterial performance in the inhabitation of oral biofilm formation in comparison with the gold standard Ti-6Al-4V implant material. Metallic glasses are superior in terms of biocorrosion and have a reduced stress shielding effect compared with their crystalline counterparts. Dynamic mechanical and thermal expansion analyses on TiZrCuPd show that these materials can be thermomechanically shaped into implants.

Structure-dynamics relationships in cryogenically deformed bulk metallic glass.

The atomistic mechanisms occurring during the processes of aging and rejuvenation in glassy materials involve very small structural rearrangements that are extremely difficult to capture experimentally. Here we use in-situ X-ray diffraction to investigate the structural rearrangements during annealing from 77 K up to the crystallization temperature in CuZrAlHfCo bulk metallic glass rejuvenated by high pressure torsion performed at cryogenic temperatures and at room temperature. Using a measure of the configurational entropy calculated from the X-ray pair correlation function, the structural footprint of the deformation-induced rejuvenation in bulk metallic glass is revealed.

ZBTB46 is a shear-sensitive transcription factor inhibiting endothelial cell proliferation via gene expression regulation of cell cycle proteins.

ZBTB46 is a transcription factor identified in classical dendritic cells and keeps dendritic cells in a quiescent state. Chromatin immunoprecipitation sequencing in dendritic cells has identified over 1300 potential gene targets of ZBTB46, affecting many processes including cell cycle. Endothelial cells (ECs) also express ZBTB46 and are mostly in a quiescent non-proliferative state.

Accelerated atherosclerosis development in C57Bl6 mice by overexpressing AAV-mediated PCSK9 and partial carotid ligation.

Studying the role of a particular gene in atherosclerosis typically requires a time-consuming and often difficult process of generating double knockouts or transgenics on ApoE or LDL receptor (LDLR) background. Recently, it was reported that adeno-associated-virus-8 (AAV8)-mediated overexpression of PCSK9 (AAV8-PCSK9) rapidly induced hyperlipidemia. However, using this method in C57BL6 wild-type (C57) mice, it took ~3 months to develop atherosclerosis.

The role of the vascular dendritic cell network in atherosclerosis.

A complex role has been described for dendritic cells (DCs) in the potentiation and control of vascular inflammation and atherosclerosis. Resident vascular DCs are found in the intima of atherosclerosis-prone vascular regions exposed to disturbed blood flow patterns. Several phenotypically and functionally distinct vascular DC subsets have been described.

Dynamic immune cell accumulation during flow-induced atherogenesis in mouse carotid artery: an expanded flow cytometry method.

Objective: Inflammation plays a central role in atherosclerosis. However, the detailed changes in the composition and quantity of leukocytes in the arterial wall during atherogenesis are not fully understood in part because of the lack of suitable methods and animal models.

Methods And Results: We developed a 10-fluorochrome, 13-parameter flow cytometry method to quantitate 7 major leukocyte subsets in a single digested arterial wall sample.

Tetrahydrobiopterin deficiency and nitric oxide synthase uncoupling contribute to atherosclerosis induced by disturbed flow.

Objective: Tetrahydrobiopterin (BH(4)) is a critical cofactor for nitric oxide (NO) synthesis by NO synthase (NOS). Recently, we demonstrated that disturbed flow produced by partial carotid ligation decreases BH(4) levels in vivo. We therefore aimed to determine whether atherosclerosis induced by disturbed flow is due to BH(4) deficiency and NOS uncoupling and whether increasing BH(4) would prevent endothelial dysfunction, plaque inflammation, and atherosclerosis.

Animal, in vitro, and ex vivo models of flow-dependent atherosclerosis: role of oxidative stress.

Atherosclerosis is an inflammatory disease preferentially occurring in curved or branched arterial regions, whereas straight parts of the arteries are protected, suggesting a close relationship between flow and atherosclerosis. However, evidence directly linking disturbed flow to atherogenesis is just emerging, thanks to the recent development of suitable animal models. In this article, we review the status of various animal, in vitro, and ex vivo models that have been used to study flow-dependent vascular biology and atherosclerosis.

A model of disturbed flow-induced atherosclerosis in mouse carotid artery by partial ligation and a simple method of RNA isolation from carotid endothelium.

Despite the well-known close association, direct evidence linking disturbed flow to atherogenesis has been lacking. We have recently used a modified version of carotid partial ligation methods to show that it acutely induces low and oscillatory flow conditions, two key characteristics of disturbed flow, in the mouse common carotid artery. Using this model, we have provided direct evidence that disturbed flow indeed leads to rapid and robust atherosclerosis development in Apolipoprotein E knockout mouse.

Discovery of novel mechanosensitive genes in vivo using mouse carotid artery endothelium exposed to disturbed flow.

Recently, we showed that disturbed flow caused by a partial ligation of mouse carotid artery rapidly induces atherosclerosis. Here, we identified mechanosensitive genes in vivo through a genome-wide microarray study using mouse endothelial RNAs isolated from the flow-disturbed left and the undisturbed right common carotid artery. We found 62 and 523 genes that changed significantly by 12 hours and 48 hours after ligation, respectively.

GTP cyclohydrolase I phosphorylation and interaction with GTP cyclohydrolase feedback regulatory protein provide novel regulation of endothelial tetrahydrobiopterin and nitric oxide.

Rationale: GTP cyclohydrolase I (GTPCH-1) is the rate-limiting enzyme involved in de novo biosynthesis of tetrahydrobiopterin (BH(4)), an essential cofactor for NO synthases and aromatic amino acid hydroxylases. GTPCH-1 undergoes negative feedback regulation by its end-product BH(4) via interaction with the GTP cyclohydrolase feedback regulatory protein (GFRP). Such a negative feedback mechanism should maintain cellular BH(4) levels within a very narrow range; however, we recently identified a phosphorylation site (S81) on human GTPCH-1 that markedly increases BH(4) production in response to laminar shear.

Partial carotid ligation is a model of acutely induced disturbed flow, leading to rapid endothelial dysfunction and atherosclerosis.

Atherosclerosis is closely associated with disturbed flow characterized by low and oscillatory shear stress, but studies directly linking disturbed flow to atherogenesis is lacking. The major reason for this has been a lack of an animal model in which disturbed flow can be acutely induced and cause atherosclerosis. Here, we characterize partial carotid ligation as a model of disturbed flow with characteristics of low and oscillatory wall shear stress.

Nerve growth factor-induced migration of endothelial cells.

Nerve growth factor (NGF) is a well known neurotropic and neurotrophic agonist in the nervous system, which recently was shown to also induce angiogenic effects in endothelial cells (ECs). To measure NGF effects on the migration of cultured ECs, an important step in neoangiogenesis, we optimized an omnidirectional migration assay using human aortic endothelial cells (HAECs) and validated the assay with human recombinant basic fibroblast growth factor (rhbFGF) and human recombinant vascular endothelial growth factor (rhVEGF). The potencies of nerve growth factor purified from various species (viper, mouse, and recombinant human) to stimulate HAEC migration was similar to that of VEGF and basic fibroblast growth factor (bFGF) (EC50 of approximately 0.

Steady unidirectional laminar flow inhibits monolayer formation by human and rat microvascular endothelial cells.

Endothelialization of artificial vascular grafts is rapid and complete in numerous animal models, including dogs and rats, but not in human patients. One possible explanation for this well-known, yet puzzling observation might be that monolayer formation of human endothelial cells (ECs), and of canine or rodent ECs, is affected differently by flow-induced shear stress. To begin testing this hypothesis, the authors wounded confluent monolayers of cultured rat and human ECs and exposed these cultures for 20 h to unidirectional steady laminar shear stress of 10 dyn/cm(2) induced by fluid flow perpendicular to the wound boundaries.