Shear stress, a major hemodynamic force acting on the vessel wall, plays an important role in phy... more Shear stress, a major hemodynamic force acting on the vessel wall, plays an important role in physiological processes such as cell growth, differentiation, remodelling, metabolism, morphology, and gene expression. We investigated the effect of shear stress on gene expression profiles in co-cultured vascular endothelial cells (ECs) and smooth muscle cells (SMCs). Human aortic ECs were cultured as a confluent monolayer on top of confluent human aortic SMCs, and the EC side of the co-culture was exposed to a laminar shear stress of 12 dyn/cm(2) for 4 or 24 h. After shearing, the ECs and SMCs were separated and RNA was extracted from the cells. The RNA samples were labelled and hybridized with cDNA array slides that contained 8694 genes. Statistical analysis showed that shear stress caused the differential expression (p < or = 0.05) of a total of 1151 genes in ECs and SMCs. In the co-cultured ECs, shear stress caused the up-regulation of 403 genes and down-regulation of 470. In the co-cultured SMCs, shear stress caused the up-regulation of 152 genes and down-regulation of 126 genes. These results provide new information on the gene expression profile and its potential functional consequences in co-cultured ECs and SMCs exposed to a physiological level of laminar shear stress. Although the effects of shear stress on gene expression in monocultured and co-cultured EC are generally similar, the response of some genes to shear stress is opposite between these two types of culture (e.g., ICAM-1 is up-regulated in monoculture and down-regulated in co-culture), which strongly indicates that EC-SMC interactions affect EC responses to shear stress.
Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286)
Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropi... more Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropipettes at a transition temperature (Tc) of 36.4"C. For resealed RBC-ghosts this transition occurs at 28.3"C (Tg). This fmdings are attributed to elastomeric transitions of hemoglobin from being gel-like to a fluid and of membrane proteins such as spectrin.
Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286)
Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropi... more Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropipettes at a transition temperature (Tc) of 36.4"C. For resealed RBC-ghosts this transition occurs at 28.3"C (Tg). This fmdings are attributed to elastomeric transitions of hemoglobin from being gel-like to a fluid and of membrane proteins such as spectrin.
Previous studies in our laboratory have shown that as the individual erythrocytes lose their defo... more Previous studies in our laboratory have shown that as the individual erythrocytes lose their deformabi1ity, the suspension viscosity increases and the shear thinning property disappears (1, 2). Significant differences in erythrocyte deformability have also been demonstrated among several animal species (3, 4), The results of these studies, as well as those by others (5, 6, 7, 8), indicate that the elastic properties of the individual erythrocytes play an important role in determining the suspension viscosity of blood as well as its shear dependence (9).
Integrins mediate cell adhesion and signal transduction at focal adhesions. Here we investigate t... more Integrins mediate cell adhesion and signal transduction at focal adhesions. Here we investigate the roles of integrin β subunits in the regulation of actin cytoskeletal structure and the activities of Rho and Rac. The overexpression of β3 integrin in Chinese hamster ovary cells enhances Rho activity and stress fiber formation, whereas the overexpression of β1 integrin increases Rac activity and lamellipodia formation. The overexpression of a mutant β1-3-1 integrin, in which the extracellular I-domain-like sequence of β1 integrin has been replaced with the corresponding sequence of β3 integrin, also enhances Rho activity and the formation of stress fibers. Our results demonstrate that β1 and β3 integrins differentially regulate the activities of Rho family GTPases and that the extracellular domains of integrin β subunits play a critical role in transducing the extracellular ligand-binding information into specific intracellular signaling events.
The ultimate cause of destruction of red blood cells (RBCs) after oxidative damage with Heinz bod... more The ultimate cause of destruction of red blood cells (RBCs) after oxidative damage with Heinz body formation is not well understood. We correlated the changes in RBC morphology and membrane protein composition after oxidant treatment with the alterations in deformability of whole cells and cell membranes. The incubation of RBCs with phenylhydrazine concentrations of 0.3 to 100 mg/dL at 37 degrees C for one hour led to a dose-dependent formation of Heinz bodies, ranging from isolated Heinz bodies at 1 mg/dL to a confluent coating of the inner membrane surface at 100 mg/dL phenylhydrazine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a large quantity of hemoglobin bound to the ghost membrane of treated RBCs. Electrophoresis with and without dithiothreitol indicated that disulfide bridges are abundant between hemoglobin molecules and are also present among membrane proteins but are not the major bond between hemoglobin and membrane. Changes of spec...
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
This study was undertaken to gain a better understanding of the fundamental mechanisms of micro- ... more This study was undertaken to gain a better understanding of the fundamental mechanisms of micro- and macrovascular heat transfer by experimentally identifying those vessels most important in the process. Tissue temperature fields around thermally nonequilibrated vessels were determined using a small temperature sensor that was guided through the rabbit thigh to generate a detailed temperature map. The measurements revealed that the lower limit of vessel size for thermal nonequilibration was 100 microns for arteries and 400 microns for veins. Local temperature fields were found around four of the five (80%) arteries that were greater than 300 microns in diameter but in only 3 of the 12 (25%) veins greater than 400 microns. These experimental results are in good agreement with previously published theoretical studies (5) in which it was concluded that thermal equilibration in the branching countercurrent vascular network of the rabbit limb occurs in vessels an order of magnitude large...
Mammalian cells are surrounded by neighbouring cells and extracellular matrix (ECM), which provid... more Mammalian cells are surrounded by neighbouring cells and extracellular matrix (ECM), which provide cells with structural support and mechanical cues that influence diverse biological processes. The Hippo pathway effectors YAP (also known as YAP1) and TAZ (also known as WWTR1) are regulated by mechanical cues and mediate cellular responses to ECM stiffness. Here we identified the Ras-related GTPase RAP2 as a key intracellular signal transducer that relays ECM rigidity signals to control mechanosensitive cellular activities through YAP and TAZ. RAP2 is activated by low ECM stiffness, and deletion of RAP2 blocks the regulation of YAP and TAZ by stiffness signals and promotes aberrant cell growth. Mechanistically, matrix stiffness acts through phospholipase Cγ1 (PLCγ1) to influence levels of phosphatidylinositol 4,5-bisphosphate and phosphatidic acid, which activates RAP2 through PDZGEF1 and PDZGEF2 (also known as RAPGEF2 and RAPGEF6). At low stiffness, active RAP2 binds to and stimulat...
Hematogenous metastasis requires tumor cells to detach from primary tumor into blood/lymphatic ci... more Hematogenous metastasis requires tumor cells to detach from primary tumor into blood/lymphatic circulation and extravasate. Tumor cells in the blood circulation system, named circulating tumor cells (CTCs), are in a suspension state, with unique cytoskeletal structure and molecular phenotype different from primary tumor cells. The aim of this study is to assess the impact of suspension state on the metastatic potential of breast cancer cells (BCCs) and study its underlying mechanism. BCCs were cultured on low-adhesion plates to mimic the suspension state. Conventional adherent culture BCCs were used as the control. This study examined the metastatic potential of adherent and suspension BCCs and . RNA sequencing analysis, siRNA, and inhibitors were used to determine the underlying molecular mechanism. The suspension state significantly increased the metastatic potential of BCCs, but slightly suppressed their tumor growth. RNA sequencing analysis revealed that the suspension state res...
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology, 2018
Hyperlipidemia induces dysfunction in the smooth muscle cells (SMCs) of the blood vessels, and th... more Hyperlipidemia induces dysfunction in the smooth muscle cells (SMCs) of the blood vessels, and the vascular remodeling that ensues is a key proatherogenic factor contributing to cardiovascular events. Chemokines and chemokine receptors play crucial roles in vascular remodeling. Here, we examined whether the hyperlipidemia-derived chemokine CCL5 and its receptor CCR5 influence vascular SMC proliferation, phenotypic switching, and explored the underlying mechanisms. Thoracoabdominal aorta were isolated from wild-type, CCL5 and CCR5 double-knockout mice (CCL5-/-CCR5-/-) fed a high-fat diet (HFD) for 12 weeks. Expression of the contractile, synthetic, and proliferation markers were assayed using immunohistochemical and western blotting. The effects of CCL5 and palmitic acid on cultured SMC proliferation and phenotypic modulation were evaluated using flow cytometry, bromodeoxyuridine (BrdU), and western blotting. Wild-type mice fed an HFD showed markedly increased total cholesterol, trig...
Mechanotransduction plays a crucial role in vascular biology. One example of this is the local re... more Mechanotransduction plays a crucial role in vascular biology. One example of this is the local regulation of vascular resistance via flow-mediated dilation (FMD). Impairment of this process is a hallmark of endothelial dysfunction and a precursor to a wide array of vascular diseases, such as hypertension and atherosclerosis. Yet the molecules responsible for sensing flow (shear stress) within endothelial cells remain largely unknown. We designed a 384-well screening system that applies shear stress on cultured cells. We identified a mechanosensitive cell line that exhibits shear stress-activated calcium transients, screened a focused RNAi library, and identified GPR68 as necessary and sufficient for shear stress responses. GPR68 is expressed in endothelial cells of small-diameter (resistance) arteries. Importantly, Gpr68-deficient mice display markedly impaired acute FMD and chronic flow-mediated outward remodeling in mesenteric arterioles. Therefore, GPR68 is an essential flow sens...
Biochemical and biophysical research communications, Mar 11, 2018
Cell migration is a critical process during development, tissue repair, and cancer metastasis. It... more Cell migration is a critical process during development, tissue repair, and cancer metastasis. It requires complex processes of cell adhesion, cytoskeletal dynamics, and force generation. Lis1 plays an important role in the migration of neurons, fibroblasts and other cell types, and is essential for normal development of the cerebral cortex. Mutations in human LIS1 gene cause classical lissencephaly (smooth brain), resulting from defects in neuronal migration. However, how Lis1 may affect force generation in migrating cells is still not fully understood. Using traction force microscopy (TFM) with live cell imaging to measure cellular traction force in migrating NIH3T3 cells, we showed that Lis1 knockdown (KD) by RNA interference (RNAi) caused reductions in cell migration and traction force against the extracellular matrix (ECM). Immunostaining of cytoskeletal components in Lis1 KD cells showed disorganization of microtubules and actin filaments. Interestingly, focal adhesions at the...
Cardiovascular disease represents one of the major causes of death across the global population. ... more Cardiovascular disease represents one of the major causes of death across the global population. Atherosclerosis, one of its most common drivers, is characterized by the gradual buildup of arterial plaque over time, which can ultimately lead to life-threatening conditions. Given the impact of the disease on public health, there is a great need for effective and noninvasive imaging modalities that can provide valuable information on its biological underpinnings during development. Here, we leverage the role of platelets in atherogenesis to design nanocarriers capable of targeting multiple biological elements relevant to plaque development. Biomimetic nanoparticles are prepared by coating platelet membrane around a synthetic nanoparticulate core, the product of which is capable of interacting with activated endothelium, foam cells, and collagen. The effects are shown to be exclusive to platelet membrane-coated nanoparticles. These biomimetic nanocarriers are not only capable of effici...
Proceedings of the National Academy of Sciences of the United States of America, Jan 30, 2018
While cell-based immunotherapy, especially chimeric antigen receptor (CAR)-expressing T cells, is... more While cell-based immunotherapy, especially chimeric antigen receptor (CAR)-expressing T cells, is becoming a paradigm-shifting therapeutic approach for cancer treatment, there is a lack of general methods to remotely and noninvasively regulate genetics in live mammalian cells and animals for cancer immunotherapy within confined local tissue space. To address this limitation, we have identified a mechanically sensitive Piezo1 ion channel (mechanosensor) that is activatable by ultrasound stimulation and integrated it with engineered genetic circuits (genetic transducer) in live HEK293T cells to convert the ultrasound-activated Piezo1 into transcriptional activities. We have further engineered the Jurkat T-cell line and primary T cells (peripheral blood mononuclear cells) to remotely sense the ultrasound wave and transduce it into transcriptional activation for the CAR expression to recognize and eradicate target tumor cells. This approach is modular and can be extended for remote-cont...
The optimal expression of endothelial nitric oxide synthase (eNOS), the hallmark of endothelial h... more The optimal expression of endothelial nitric oxide synthase (eNOS), the hallmark of endothelial homeostasis, is vital to vascular function. Dynamically regulated by various stimuli, eNOS expression is modulated at transcriptional, post-transcriptional, and post-translational levels. However, epigenetic modulations of eNOS, particularly through long non-coding RNAs (lncRNAs) and chromatin remodeling, remain to be explored. Here we identify an enhancer-associated lncRNA that enhances eNOS expression (LEENE). Combining RNA-sequencing and chromatin conformation capture methods, we demonstrate that LEENE is co-regulated with eNOS and that its enhancer resides in proximity to eNOS promoter in endothelial cells (ECs). Gain- and Loss-of-function of LEENE differentially regulate eNOS expression and EC function. Mechanistically, LEENE facilitates the recruitment of RNA Pol II to the eNOS promoter to enhance eNOS nascent RNA transcription. Our findings unravel a new layer in eNOS regulation an...
Proceedings of the National Academy of Sciences of the United States of America, Jan 2, 2018
Leukocyte transmigration across vessel walls is a critical step in the innate immune response. Up... more Leukocyte transmigration across vessel walls is a critical step in the innate immune response. Upon their activation and firm adhesion to vascular endothelial cells (VECs), leukocytes preferentially extravasate across junctional gaps in the endothelial monolayer (paracellular diapedesis). It has been hypothesized that VECs facilitate paracellular diapedesis by opening their cell-cell junctions in response to the presence of an adhering leukocyte. However, it is unclear how leukocytes interact mechanically with VECs to open the VEC junctions and migrate across the endothelium. In this study, we measured the spatial and temporal evolution of the 3D traction stresses generated by the leukocytes and VECs to elucidate the sequence of mechanical events involved in paracellular diapedesis. Our measurements suggest that the contractile stresses exerted by the leukocytes and the VECs can separately perturb the junctional tensions of VECs to result in the opening of gaps before the initiation...
Shear stress, a major hemodynamic force acting on the vessel wall, plays an important role in phy... more Shear stress, a major hemodynamic force acting on the vessel wall, plays an important role in physiological processes such as cell growth, differentiation, remodelling, metabolism, morphology, and gene expression. We investigated the effect of shear stress on gene expression profiles in co-cultured vascular endothelial cells (ECs) and smooth muscle cells (SMCs). Human aortic ECs were cultured as a confluent monolayer on top of confluent human aortic SMCs, and the EC side of the co-culture was exposed to a laminar shear stress of 12 dyn/cm(2) for 4 or 24 h. After shearing, the ECs and SMCs were separated and RNA was extracted from the cells. The RNA samples were labelled and hybridized with cDNA array slides that contained 8694 genes. Statistical analysis showed that shear stress caused the differential expression (p < or = 0.05) of a total of 1151 genes in ECs and SMCs. In the co-cultured ECs, shear stress caused the up-regulation of 403 genes and down-regulation of 470. In the co-cultured SMCs, shear stress caused the up-regulation of 152 genes and down-regulation of 126 genes. These results provide new information on the gene expression profile and its potential functional consequences in co-cultured ECs and SMCs exposed to a physiological level of laminar shear stress. Although the effects of shear stress on gene expression in monocultured and co-cultured EC are generally similar, the response of some genes to shear stress is opposite between these two types of culture (e.g., ICAM-1 is up-regulated in monoculture and down-regulated in co-culture), which strongly indicates that EC-SMC interactions affect EC responses to shear stress.
Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286)
Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropi... more Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropipettes at a transition temperature (Tc) of 36.4"C. For resealed RBC-ghosts this transition occurs at 28.3"C (Tg). This fmdings are attributed to elastomeric transitions of hemoglobin from being gel-like to a fluid and of membrane proteins such as spectrin.
Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Vol.20 Biomedical Engineering Towards the Year 2000 and Beyond (Cat. No.98CH36286)
Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropi... more Human red blood cells (RBC) undergo a sudden change from blocking to passing through l-pm-micropipettes at a transition temperature (Tc) of 36.4"C. For resealed RBC-ghosts this transition occurs at 28.3"C (Tg). This fmdings are attributed to elastomeric transitions of hemoglobin from being gel-like to a fluid and of membrane proteins such as spectrin.
Previous studies in our laboratory have shown that as the individual erythrocytes lose their defo... more Previous studies in our laboratory have shown that as the individual erythrocytes lose their deformabi1ity, the suspension viscosity increases and the shear thinning property disappears (1, 2). Significant differences in erythrocyte deformability have also been demonstrated among several animal species (3, 4), The results of these studies, as well as those by others (5, 6, 7, 8), indicate that the elastic properties of the individual erythrocytes play an important role in determining the suspension viscosity of blood as well as its shear dependence (9).
Integrins mediate cell adhesion and signal transduction at focal adhesions. Here we investigate t... more Integrins mediate cell adhesion and signal transduction at focal adhesions. Here we investigate the roles of integrin β subunits in the regulation of actin cytoskeletal structure and the activities of Rho and Rac. The overexpression of β3 integrin in Chinese hamster ovary cells enhances Rho activity and stress fiber formation, whereas the overexpression of β1 integrin increases Rac activity and lamellipodia formation. The overexpression of a mutant β1-3-1 integrin, in which the extracellular I-domain-like sequence of β1 integrin has been replaced with the corresponding sequence of β3 integrin, also enhances Rho activity and the formation of stress fibers. Our results demonstrate that β1 and β3 integrins differentially regulate the activities of Rho family GTPases and that the extracellular domains of integrin β subunits play a critical role in transducing the extracellular ligand-binding information into specific intracellular signaling events.
The ultimate cause of destruction of red blood cells (RBCs) after oxidative damage with Heinz bod... more The ultimate cause of destruction of red blood cells (RBCs) after oxidative damage with Heinz body formation is not well understood. We correlated the changes in RBC morphology and membrane protein composition after oxidant treatment with the alterations in deformability of whole cells and cell membranes. The incubation of RBCs with phenylhydrazine concentrations of 0.3 to 100 mg/dL at 37 degrees C for one hour led to a dose-dependent formation of Heinz bodies, ranging from isolated Heinz bodies at 1 mg/dL to a confluent coating of the inner membrane surface at 100 mg/dL phenylhydrazine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of a large quantity of hemoglobin bound to the ghost membrane of treated RBCs. Electrophoresis with and without dithiothreitol indicated that disulfide bridges are abundant between hemoglobin molecules and are also present among membrane proteins but are not the major bond between hemoglobin and membrane. Changes of spec...
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
This study was undertaken to gain a better understanding of the fundamental mechanisms of micro- ... more This study was undertaken to gain a better understanding of the fundamental mechanisms of micro- and macrovascular heat transfer by experimentally identifying those vessels most important in the process. Tissue temperature fields around thermally nonequilibrated vessels were determined using a small temperature sensor that was guided through the rabbit thigh to generate a detailed temperature map. The measurements revealed that the lower limit of vessel size for thermal nonequilibration was 100 microns for arteries and 400 microns for veins. Local temperature fields were found around four of the five (80%) arteries that were greater than 300 microns in diameter but in only 3 of the 12 (25%) veins greater than 400 microns. These experimental results are in good agreement with previously published theoretical studies (5) in which it was concluded that thermal equilibration in the branching countercurrent vascular network of the rabbit limb occurs in vessels an order of magnitude large...
Mammalian cells are surrounded by neighbouring cells and extracellular matrix (ECM), which provid... more Mammalian cells are surrounded by neighbouring cells and extracellular matrix (ECM), which provide cells with structural support and mechanical cues that influence diverse biological processes. The Hippo pathway effectors YAP (also known as YAP1) and TAZ (also known as WWTR1) are regulated by mechanical cues and mediate cellular responses to ECM stiffness. Here we identified the Ras-related GTPase RAP2 as a key intracellular signal transducer that relays ECM rigidity signals to control mechanosensitive cellular activities through YAP and TAZ. RAP2 is activated by low ECM stiffness, and deletion of RAP2 blocks the regulation of YAP and TAZ by stiffness signals and promotes aberrant cell growth. Mechanistically, matrix stiffness acts through phospholipase Cγ1 (PLCγ1) to influence levels of phosphatidylinositol 4,5-bisphosphate and phosphatidic acid, which activates RAP2 through PDZGEF1 and PDZGEF2 (also known as RAPGEF2 and RAPGEF6). At low stiffness, active RAP2 binds to and stimulat...
Hematogenous metastasis requires tumor cells to detach from primary tumor into blood/lymphatic ci... more Hematogenous metastasis requires tumor cells to detach from primary tumor into blood/lymphatic circulation and extravasate. Tumor cells in the blood circulation system, named circulating tumor cells (CTCs), are in a suspension state, with unique cytoskeletal structure and molecular phenotype different from primary tumor cells. The aim of this study is to assess the impact of suspension state on the metastatic potential of breast cancer cells (BCCs) and study its underlying mechanism. BCCs were cultured on low-adhesion plates to mimic the suspension state. Conventional adherent culture BCCs were used as the control. This study examined the metastatic potential of adherent and suspension BCCs and . RNA sequencing analysis, siRNA, and inhibitors were used to determine the underlying molecular mechanism. The suspension state significantly increased the metastatic potential of BCCs, but slightly suppressed their tumor growth. RNA sequencing analysis revealed that the suspension state res...
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology, 2018
Hyperlipidemia induces dysfunction in the smooth muscle cells (SMCs) of the blood vessels, and th... more Hyperlipidemia induces dysfunction in the smooth muscle cells (SMCs) of the blood vessels, and the vascular remodeling that ensues is a key proatherogenic factor contributing to cardiovascular events. Chemokines and chemokine receptors play crucial roles in vascular remodeling. Here, we examined whether the hyperlipidemia-derived chemokine CCL5 and its receptor CCR5 influence vascular SMC proliferation, phenotypic switching, and explored the underlying mechanisms. Thoracoabdominal aorta were isolated from wild-type, CCL5 and CCR5 double-knockout mice (CCL5-/-CCR5-/-) fed a high-fat diet (HFD) for 12 weeks. Expression of the contractile, synthetic, and proliferation markers were assayed using immunohistochemical and western blotting. The effects of CCL5 and palmitic acid on cultured SMC proliferation and phenotypic modulation were evaluated using flow cytometry, bromodeoxyuridine (BrdU), and western blotting. Wild-type mice fed an HFD showed markedly increased total cholesterol, trig...
Mechanotransduction plays a crucial role in vascular biology. One example of this is the local re... more Mechanotransduction plays a crucial role in vascular biology. One example of this is the local regulation of vascular resistance via flow-mediated dilation (FMD). Impairment of this process is a hallmark of endothelial dysfunction and a precursor to a wide array of vascular diseases, such as hypertension and atherosclerosis. Yet the molecules responsible for sensing flow (shear stress) within endothelial cells remain largely unknown. We designed a 384-well screening system that applies shear stress on cultured cells. We identified a mechanosensitive cell line that exhibits shear stress-activated calcium transients, screened a focused RNAi library, and identified GPR68 as necessary and sufficient for shear stress responses. GPR68 is expressed in endothelial cells of small-diameter (resistance) arteries. Importantly, Gpr68-deficient mice display markedly impaired acute FMD and chronic flow-mediated outward remodeling in mesenteric arterioles. Therefore, GPR68 is an essential flow sens...
Biochemical and biophysical research communications, Mar 11, 2018
Cell migration is a critical process during development, tissue repair, and cancer metastasis. It... more Cell migration is a critical process during development, tissue repair, and cancer metastasis. It requires complex processes of cell adhesion, cytoskeletal dynamics, and force generation. Lis1 plays an important role in the migration of neurons, fibroblasts and other cell types, and is essential for normal development of the cerebral cortex. Mutations in human LIS1 gene cause classical lissencephaly (smooth brain), resulting from defects in neuronal migration. However, how Lis1 may affect force generation in migrating cells is still not fully understood. Using traction force microscopy (TFM) with live cell imaging to measure cellular traction force in migrating NIH3T3 cells, we showed that Lis1 knockdown (KD) by RNA interference (RNAi) caused reductions in cell migration and traction force against the extracellular matrix (ECM). Immunostaining of cytoskeletal components in Lis1 KD cells showed disorganization of microtubules and actin filaments. Interestingly, focal adhesions at the...
Cardiovascular disease represents one of the major causes of death across the global population. ... more Cardiovascular disease represents one of the major causes of death across the global population. Atherosclerosis, one of its most common drivers, is characterized by the gradual buildup of arterial plaque over time, which can ultimately lead to life-threatening conditions. Given the impact of the disease on public health, there is a great need for effective and noninvasive imaging modalities that can provide valuable information on its biological underpinnings during development. Here, we leverage the role of platelets in atherogenesis to design nanocarriers capable of targeting multiple biological elements relevant to plaque development. Biomimetic nanoparticles are prepared by coating platelet membrane around a synthetic nanoparticulate core, the product of which is capable of interacting with activated endothelium, foam cells, and collagen. The effects are shown to be exclusive to platelet membrane-coated nanoparticles. These biomimetic nanocarriers are not only capable of effici...
Proceedings of the National Academy of Sciences of the United States of America, Jan 30, 2018
While cell-based immunotherapy, especially chimeric antigen receptor (CAR)-expressing T cells, is... more While cell-based immunotherapy, especially chimeric antigen receptor (CAR)-expressing T cells, is becoming a paradigm-shifting therapeutic approach for cancer treatment, there is a lack of general methods to remotely and noninvasively regulate genetics in live mammalian cells and animals for cancer immunotherapy within confined local tissue space. To address this limitation, we have identified a mechanically sensitive Piezo1 ion channel (mechanosensor) that is activatable by ultrasound stimulation and integrated it with engineered genetic circuits (genetic transducer) in live HEK293T cells to convert the ultrasound-activated Piezo1 into transcriptional activities. We have further engineered the Jurkat T-cell line and primary T cells (peripheral blood mononuclear cells) to remotely sense the ultrasound wave and transduce it into transcriptional activation for the CAR expression to recognize and eradicate target tumor cells. This approach is modular and can be extended for remote-cont...
The optimal expression of endothelial nitric oxide synthase (eNOS), the hallmark of endothelial h... more The optimal expression of endothelial nitric oxide synthase (eNOS), the hallmark of endothelial homeostasis, is vital to vascular function. Dynamically regulated by various stimuli, eNOS expression is modulated at transcriptional, post-transcriptional, and post-translational levels. However, epigenetic modulations of eNOS, particularly through long non-coding RNAs (lncRNAs) and chromatin remodeling, remain to be explored. Here we identify an enhancer-associated lncRNA that enhances eNOS expression (LEENE). Combining RNA-sequencing and chromatin conformation capture methods, we demonstrate that LEENE is co-regulated with eNOS and that its enhancer resides in proximity to eNOS promoter in endothelial cells (ECs). Gain- and Loss-of-function of LEENE differentially regulate eNOS expression and EC function. Mechanistically, LEENE facilitates the recruitment of RNA Pol II to the eNOS promoter to enhance eNOS nascent RNA transcription. Our findings unravel a new layer in eNOS regulation an...
Proceedings of the National Academy of Sciences of the United States of America, Jan 2, 2018
Leukocyte transmigration across vessel walls is a critical step in the innate immune response. Up... more Leukocyte transmigration across vessel walls is a critical step in the innate immune response. Upon their activation and firm adhesion to vascular endothelial cells (VECs), leukocytes preferentially extravasate across junctional gaps in the endothelial monolayer (paracellular diapedesis). It has been hypothesized that VECs facilitate paracellular diapedesis by opening their cell-cell junctions in response to the presence of an adhering leukocyte. However, it is unclear how leukocytes interact mechanically with VECs to open the VEC junctions and migrate across the endothelium. In this study, we measured the spatial and temporal evolution of the 3D traction stresses generated by the leukocytes and VECs to elucidate the sequence of mechanical events involved in paracellular diapedesis. Our measurements suggest that the contractile stresses exerted by the leukocytes and the VECs can separately perturb the junctional tensions of VECs to result in the opening of gaps before the initiation...
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Papers by Shu Chien