Direct Activity Measurement of Heterotrimeric Gi Proteins and Gq Protein By Effector Pulldown.

Studying G protein-coupled receptor (GPCR) activation of heterotrimeric G proteins is crucial for understanding diverse physiological processes and developing novel therapeutics. Traditional methods to assay GPCR activation of G proteins, including assays of second messengers and biosensors, involve complex or indirect procedures. However, second messengers like cAMP and calcium are not direct readouts of GPCR activity due to signaling crosstalk, while biosensors can have undesired consequences due to structural alteration caused by fluorescent protein insertion.

PIEZO1 Overexpression in Hereditary Hemorrhagic Telangiectasia Arteriovenous Malformations.

Background: Hereditary hemorrhagic telangiectasia is an inherited vascular disorder characterized by arteriovenous malformations (AVMs). Loss-of-function variations in activin receptor-like kinase 1 () cause type 2 hereditary hemorrhagic telangiectasia, and knockout mice develop AVMs, along with overactivation of vascular endothelial growth factor receptor 2/phosphoinositide 3-kinase/AKT signaling. The full spectrum of signaling alterations resulting from variations remains unknown, and more effective and specific inhibitors to combat AVM formation in patients are needed.

Latrophilin mediates flow activation of Notch to control vascular endothelial phenotype and atherosclerosis.

Fluid shear stress (FSS) is a major determinant of endothelial cell (EC) phenotype, with physiological laminar FSS promoting arterial identity and stability, whereas disturbed FSS promotes atherosclerosis. We previously identified the adhesion G protein-coupled receptor (GPCR) Latrophilin-2 (Lphn2) as a junctional protein required for FSS activation of the PECAM1/VE-cadherin/VEGFR2/PlexinD1 junctional mechanosensory pathway, which promotes EC inflammatory activation and atherogenesis in disturbed flow. We now report that Lphn2 endothelial cell specific knockout (ECKO) hyperlipidemic mice develop larger plaques than controls, opposite from PECAM-1 KO mice.

Latrophilin-2 Orchestrates Endothelial Flow-Mediated Smad1/5 Activation via Endoglin and Shank3.

Fluid shear stress (FSS) from blood flow critically determines vascular stability and remodeling. The Smad1/5 pathway is activated by FSS through the BMP9/10 receptors Alk1 and Endoglin, with a maximal activation occurring at physiological magnitudes of FSS, to promote vascular homeostasis. Here, we report that the adhesion G protein-coupled receptor Latrophilin-2 (Lphn2), previously found to mediate flow activation of the canonical junctional complex, is required for flow-mediated Smad1/5 activation in endothelial cells.

Focal adhesion-derived liquid-liquid phase separations regulate mRNA translation.

Liquid-liquid phase separation (LLPS) has emerged as a major organizing principle in cells. Recent work showed that multiple components of integrin-mediated focal adhesions, including p130Cas can form LLPS, which govern adhesion dynamics and related cell behaviors. In this study, we found that the focal adhesion protein p130Cas drives the formation of structures with the characteristics of LLPS that bud from focal adhesions into the cytoplasm.

A Survey for Human Tissue-Level Determinants of CAV1 Regulation and Function.

CAV1 is a protein-coding gene linked to several disorders, including cancer, lipodystrophy, and cardiovascular diseases. While its ability to respond to various mechanical and metabolic stimuli has been documented, a comprehensive understanding of its physiological regulation in humans is lacking. We leveraged the comprehensiveness of human post-mortem tissue data from the Genotype-Tissue Expression (GTEx) consortium, systematically exploring the sources of variability in CAV1 transcriptional levels using extensive bulk and single-nuclei RNA-seq datasets.

Fluid Shear Stress-Regulated Vascular Remodeling: Past, Present, and Future.

The vascular system remodels throughout life to ensure adequate perfusion of tissues as they grow, regress, or change metabolic activity. Angiogenesis, the sprouting of new blood vessels to expand the capillary network, versus regression, in which endothelial cells die or migrate away to remove unneeded capillaries, controls capillary density. In addition, upstream arteries adjust their diameters to optimize blood flow to downstream vascular beds, which is controlled primarily by vascular endothelial cells sensing fluid shear stress (FSS) from blood flow.

Short-term disruption of TGF-β signaling in adult mice renders the aorta vulnerable to hypertension-induced dissection.

Hypertension and transient increases in blood pressure from extreme exertion are risk factors for aortic dissection in patients with age-related vascular degeneration or inherited connective tissue disorders. Yet, a common experimental model of angiotensin II-induced aortopathy in mice appears independent of high blood pressure, as lesions do not occur in response to an alternative vasoconstrictor, norepinephrine, and are not prevented by cotreatment with a vasodilator, hydralazine. We investigated vasoconstrictor administration to adult mice following 1 week of disrupted TGF-β signaling in smooth muscle cells (SMCs).

cSTAR analysis identifies endothelial cell cycle as a key regulator of flow-dependent artery remodeling.

Fluid shear stress (FSS) from blood flow sensed by vascular endothelial cells (ECs) determines vessel behavior, but regulatory mechanisms are only partially understood. We used cell state transition assessment and regulation (cSTAR), a powerful computational method, to elucidate EC transcriptomic states under low shear stress (LSS), physiological shear stress (PSS), high shear stress (HSS), and oscillatory shear stress (OSS) that induce vessel inward remodeling, stabilization, outward remodeling, or disease susceptibility, respectively. Combined with a publicly available database on EC transcriptomic responses to drug treatments, this approach inferred a regulatory network controlling EC states and made several notable predictions.

Conformational response of αβ and αβ integrins to force.

As major adhesion receptors, integrins transmit biochemical and mechanical signals across the plasma membrane. These functions are regulated by transitions between bent and extended conformations and modulated by force. To understand how force on integrins mediates cellular mechanosensing, we compared two highly homologous integrins, αβ and αβ.

Polycomb Repressive Complex 2 promotes atherosclerotic plaque vulnerability.

Atherosclerotic cardiovascular disease (ASCVD), the leading cause of mortality worldwide, is driven by endothelial cell inflammatory activation and counter-balanced by anti-inflammatory transcription factors Klf2 and Klf4 (Klf2/4). Understanding vascular endothelial inflammation to develop effective treatments is thus essential. Here, we identify, Polycomb Repressive Complex (PRC) 2, which blocks gene transcription by trimethylating histone3 Lysine27 in gene promoter/enhancers, as a potent, therapeutically targetable determinant of vascular inflammation and ASCVD progression.

Integrins as Drug Targets in Vascular and Related Diseases.

Integrins are transmembrane receptors that, as critical participants in a vast range of pathological processes, are potential therapeutic targets. However, in only a few cases has the promise been realized by drug approval. In this review, we briefly review basic integrin biology and participation in disease, challenges in the development of safe, effective integrin-targeted therapies, and recent advances that may lead to progress.

DNA nanodevice for analysis of force-activated protein extension and interactions.

Force-induced changes in protein structure and function mediate cellular responses to mechanical stresses. Existing methods to study protein conformation under mechanical force are incompatible with biochemical and structural analysis. Taking advantage of DNA nanotechnology, including the well-defined geometry of DNA origami and programmable mechanics of DNA hairpins, we built a nanodevice to apply controlled forces to proteins.

DNA-Based Molecular Clamp for Probing Protein Interactions and Structure under Force.

Cellular mechanotransduction, a process central to cell biology, embryogenesis, adult physiology, and multiple diseases, is thought to be mediated by force-driven changes in protein conformation that control protein function. However, methods to study proteins under defined mechanical loads on a biochemical scale are lacking. We report the development of a DNA-based device in which the transition between single- and double-stranded DNA applies tension to an attached protein.

A KLF2-BMPER-Smad1/5 checkpoint regulates high fluid shear stress-mediated artery remodeling.

Vascular remodeling to match arterial diameter to tissue requirements commonly fails in ischemic disease. Endothelial cells sense fluid shear stress (FSS) from blood flow to maintain FSS within a narrow range in healthy vessels. Thus, high FSS induces vessel outward remodeling, but mechanisms are poorly understood.

Cellular stiffness sensing through talin 1 in tissue mechanical homeostasis.

Tissue mechanical properties are determined mainly by the extracellular matrix (ECM) and actively maintained by resident cells. Despite its broad importance to biology and medicine, tissue mechanical homeostasis remains poorly understood. To explore cell-mediated control of tissue stiffness, we developed mutations in the mechanosensitive protein talin 1 to alter cellular sensing of ECM.

Controversy in mechanotransduction - the role of endothelial cell-cell junctions in fluid shear stress sensing.

Fluid shear stress (FSS) from blood flow, sensed by the vascular endothelial cells (ECs) that line all blood vessels, regulates vascular development during embryogenesis, controls adult vascular physiology and determines the location of atherosclerotic plaque formation. Although a number of papers have reported a crucial role for cell-cell adhesions or adhesion receptors in these processes, a recent publication has challenged this paradigm, presenting evidence that ECs can very rapidly align in fluid flow as single cells without cell-cell contacts. To address this controversy, four independent laboratories assessed EC alignment in fluid flow across a range of EC cell types.

Latrophilin-2 mediates fluid shear stress mechanotransduction at endothelial junctions.

Endothelial cell responses to fluid shear stress from blood flow are crucial for vascular development, function and disease. A complex of PECAM-1, VE-cadherin, VEGF receptors (VEGFRs) and PlexinD1 located at cell-cell junctions mediates many of these events. But available evidence suggests that another mechanosensor upstream of PECAM-1 initiates signaling.

A DNA-based molecular clamp for probing protein interactions and structure under force.

Cellular mechanotransduction, a process central to cell biology, embryogenesis, adult physiology and multiple diseases, is thought to be mediated by force-driven changes in protein conformation that control protein function. However, methods to study proteins under defined mechanical loads on a biochemical scale are lacking. We report the development of a DNA based device in which the transition between single-stranded and double-stranded DNA applies tension to an attached protein.

Latrophilin-2 mediates fluid shear stress mechanotransduction at endothelial junctions.

Endothelial cell responses to fluid shear stress from blood flow are crucial for vascular development, function, and disease. A complex of PECAM-1, VE-cadherin, VEGF receptors (VEGFRs), and Plexin D1 located at cell-cell junctions mediates many of these events. However, available evidence suggests that another mechanosensor upstream of PECAM-1 initiates signaling.