Project description:The mechanisms by which physical forces regulate cells to determine complexities of vascular structure and function are enigmatic. Here we show the role the ion channel subunit Piezo1 (FAM38A). Disruption of mouse Piezo1 gene disturbed vascular development and was embryonic lethal within days of the heart beating to cause blood flow. Importance of Piezo channels as sensors of blood flow was indicated by Piezo1 dependence of shear stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer shear stress sensitivity on cells that otherwise lacked. Downstream of this calcium influx was proteoase activity and spatial organization of endothelial cells to the polarity of the applied force. Without Piezo1, normal endothelial cell organization was lacking. The data suggest Piezo1 channels as pivotal integrators of vascular architacture with physiological mechanical force.
Project description:PIEZO1 is a mechanically-activated ion channel that contributes to flow sensing in vascular endothelium. Moreover, deletion of endothelial PIEZO1 was recently found to suppress activation of Notch1 target genes in hepatic microvascular endothelium. Here, because of the liver’s dominant role in lipid regulation, we set out to test the novel hypothesis that endothelial PIEZO1 regulates hepatic lipid homeostasis. We performed bulk RNA sequencing on PIEZO1-deleted mice exposed to chow and high fat diets. Our transcriptomics analysis reveal unexpected relevance to lipid and glucose homeostasis.
Project description:Reactive astrocytes are typically studied in models that cause irreversible mechanical damage to axons, neuronal cell bodies, and glia. We evaluated the response of astrocytes in the optic nerve head to a subtle injury induced by a brief, mild elevation of the intraocular pressure. Astrocytes demonstrated reactive remodeling showing hypertrophy, process retraction and simplification of their shape. We used microarray to indentify differentially expressed genes and to investigate the molecular mechanisms of astrogliosis in response to this subtle injury. Six- to eight-week old C57Bl/6 male mice were used in this experiment. One eye underwent an elevation in intraocular pressure to 30 mmHg for 1 hour and then allowed to recover for 3 days. The contralateral eye served as a control. Due to the small tissue size of the mouse optic nerve head, two optic nerve heads were pooled together for each microarray chip. We used 10 mice to generate five biological replicates for each condition.
Project description:Aging of the vasculature is associated with detrimental changes in vascular smooth muscle cell (VSMC) mechanosensitivity to extrinsic forces in their surrounding microenvironment. However, how chronological aging alters VSMCs’ ability to sense and adapt to mechanical perturbations remains unexplored. Here, we show defective VSMC mechanosensation in aging measured with ultrasound tweezers-based micromechanical system, force instantaneous frequency spectrum and transcriptome analyses. The mechanobiological study reveals thataged VSMCs adapt a relatively inert solid-like state with altered actin cytoskeletal integrity, resulting in an impairment in their mechanosensitivity and dynamic mechanoresponse to mechanical perturbations. The aging-associated decline in mechanosensation behaviors is mediated by hyperactivity of Piezo1-dependent calcium signaling. Inhibition of Piezo1 alleviates vascular aging and partially restores the loss in dynamic contractile properties in aged cells. Altogether, our study reveals the novel signaling pathway underlying aging-associated aberrant mechanosensation in VSMC and identifies Piezo1 as a potential therapeutic mechanobiological target to alleviate vascular aging.
Project description:Mechanical overload of the vascular wall is a pathological hallmark of life-threatening abdominal aortic aneurysms (AAA). However, how this mechanical stress resonates at the unicellular level of vascular smooth muscle cells (VSMC) is undefined. Here, we combined novel tweezers-based micromechanical system and single-cell RNA sequencing to map defective mechano-phenotype signatures of VSMC in AAA. Notably, theoretical modelling predicted that cytoskeleton alterations fueled cell membrane tension of VSMC, thereby modulating their mechanoallostatic responses which were validated by live micromechanical measurements. Mechanistically, VSMC gradually adopted a mechanically solid-like state by upregulating CSK crosslinker, α-actinin2, in the presence of AAA-promoting signal, Netrin-1, thereby directly powering the activity of mechanosensory ion channel Piezo1. Inhibition of Piezo1 prevented mice from developing AAA by alleviating pathological vascular remodeling. Our findings demonstrate that deviations of mechanosensation behaviors of VSMC is detrimental for AAA and identifies Piezo1 as a novel culprit of mechanically fatigued aorta in AAA.
Project description:Aging of the vasculature is associated with detrimental changes in vascular smooth muscle cell (VSMC) mechanosensitivity to extrinsic forces in their surrounding microenvironment. However, how chronological aging alters VSMCs’ ability to sense and adapt to mechanical perturbations remains unexplored. Here, we show defective VSMC mechanosensation in aging measured with ultrasound tweezers-based micromechanical system, force instantaneous frequency spectrum and transcriptome analyses. The mechanobiological study reveals thataged VSMCs adapt a relatively inert solid-like state with altered actin cytoskeletal integrity, resulting in an impairment in their mechanosensitivity and dynamic mechanoresponse to mechanical perturbations. The aging-associated decline in mechanosensation behaviors is mediated by hyperactivity of Piezo1-dependent calcium signaling. Inhibition of Piezo1 alleviates vascular aging and partially restores the loss in dynamic contractile properties in aged cells. Altogether, our study reveals the novel signaling pathway underlying aging-associated aberrant mechanosensation in VSMC and identifies Piezo1 as a potential therapeutic mechanobiological target to alleviate vascular aging.
Project description:The role of pathological vascular degeneration in cirrhosis remains poorly understood. In this study, we engineered multidimensional vascular models to replicate the pathological characteristics of liver sinusoidal endothelial cells (LSECs) at various fibrosis stages. Our investigation revealed that LSEC response to hydrostatic pressure is matrix stiffness-dependent, with LSECs survival when cultured on soft matrices, while those cultured on hard matrices experiencing cellular damage. The biomimic vascular in vitro model enabled us to identify GPR116 as a crucial membrane receptor of LSECs to sense and respond to hydrostatic pressure. GPR116 is specifically expressed in liver endothelial cells, and silencing GPR116 effectively protected the endothelial cells from hydrostatic pressure-induced damage on hard matrix, consequently inhibiting hepatic stellate cell activation and collagen remodeling. Thus, our findings highlight GPR116 as an indispensable pressure sensor in hepatic sinusoidal endothelium, playing a pivotal role in vascular remodeling during cirrhosis.
Project description:The role of pathological vascular degeneration in cirrhosis remains poorly understood. In this study, we engineered multidimensional vascular models to replicate the pathological characteristics of liver sinusoidal endothelial cells (LSECs) at various fibrosis stages. Our investigation revealed that LSEC response to hydrostatic pressure is matrix stiffness-dependent, with LSECs survival when cultured on soft matrices, while those cultured on hard matrices experiencing cellular damage. The biomimic vascular in vitro model enabled us to identify GPR116 as a crucial membrane receptor of LSECs to sense and respond to hydrostatic pressure. GPR116 is specifically expressed in liver endothelial cells, and silencing GPR116 effectively protected the endothelial cells from hydrostatic pressure-induced damage on hard matrix, consequently inhibiting hepatic stellate cell activation and collagen remodeling. Thus, our findings highlight GPR116 as an indispensable pressure sensor in hepatic sinusoidal endothelium, playing a pivotal role in vascular remodeling during cirrhosis.