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https://www.readbyqxmd.com/read/29160307/a-non-canonical-notch-complex-regulates-adherens-junctions-and-vascular-barrier-function
#1
William J Polacheck, Matthew L Kutys, Jinling Yang, Jeroen Eyckmans, Yinyu Wu, Hema Vasavada, Karen K Hirschi, Christopher S Chen
The vascular barrier that separates blood from tissues is actively regulated by the endothelium and is essential for transport, inflammation, and haemostasis1. Haemodynamic shear stress plays a critical role in maintaining endothelial barrier function2, but how this occurs remains unknown. Here, using an engineered organotypic model of perfused microvessels and confirming in mouse models, we identify that activation of the Notch1 transmembrane receptor directly regulates vascular barrier function through a non-canonical, transcription independent signalling mechanism that drives adherens junction assembly...
November 13, 2017: Nature
https://www.readbyqxmd.com/read/29158322/optogenetic-activation-of-ephb2-receptor-in-dendrites-induced-actin-polymerization-by-activating-arg-kinase
#2
Clifford Locke, Kazuya Machida, Yi Wu, Ji Yu
Erythropoietin-producing hepatocellular (Eph) receptors regulate a wide array of developmental processes by responding to cell-cell contacts. EphB2 is well-expressed in brain and known to be important for dendritic spine development, as well as for the maintenance of the synapses, although the mechanisms of these functions have not been fully understood. Here we studied EphB2's functions in hippocampal neurons with an optogenetic approach, which allows us to specify spatial regions of signal activation and monitor in real-time the consequences of signal activation...
November 20, 2017: Biology Open
https://www.readbyqxmd.com/read/29155102/targeting-of-rac1-prevents-bronchoconstriction-and-airway-hyperresponsiveness
#3
Gwennan André-Grégoire, Florian Dilasser, Julie Chesné, Faouzi Braza, Antoine Magnan, Gervaise Loirand, Vincent Sauzeau
BACKGROUND: The molecular mechanisms responsible for airway smooth muscle cells (aSMC) contraction and proliferation in airway hyperresponsiveness (AHR) associated with asthma are still largely unknown. The small GTPases of the Rho family (RhoA, Rac1 and Cdc42) play a central role in SMC functions including migration, proliferation and contraction. OBJECTIVE: The objective of this study is to identify the role of Rac1 in aSMC contraction and to investigate its involvement in AHR associated with allergic asthma...
November 15, 2017: Journal of Allergy and Clinical Immunology
https://www.readbyqxmd.com/read/29154191/integrin-cd11b-mediates-%C3%AE-synuclein-induced-activation-of-nadph-oxidase-through-a-rho-dependent-pathway
#4
Liyan Hou, Xiuqi Bao, Caixia Zang, Hanyu Yang, Fuqiang Sun, Yuning Che, Xuefei Wu, Shao Li, Dan Zhang, Qingshan Wang
The activation of microglial NADPH oxidase (NOX2) induced by α-synuclein has been implicated in Parkinson's disease (PD) and other synucleinopathies. However, how α-synuclein activates NOX2 remains unclear. Previous study revealed that both toll-like receptor 2 (TLR2) and integrin play important roles in α-synuclein-induced microglial activation. In this study, we found that blocking CD11b, the α chain of integrin αMβ2, but not TLR2 attenuated α-synuclein-induced NOX2 activation in microglia. The involvement of CD11b in α-synuclein-induced activation of NOX2 was further confirmed in CD11b(-/-) microglia by showing reduced membrane translocation of NOX2 cytosolic subunit p47(phox) and superoxide production...
November 9, 2017: Redox Biology
https://www.readbyqxmd.com/read/29145128/microgravity-simulation-activates-cdc42-via-rap1gds1-to-promote-vascular-branch-morphogenesis-during-vasculogenesis
#5
Shouli Wang, Zhao Yin, Bei Zhao, Yanmei Qi, Jie Liu, Saum A Rahimi, Leonard Y Lee, Shaohua Li
Gravity plays an important role in normal tissue maintenance. The ability of stem cells to repair tissue loss in space through regeneration and differentiation remains largely unknown. To investigate the impact of microgravity on blood vessel formation from pluripotent stem cells, we employed the embryoid body (EB) model for vasculogenesis and simulated microgravity by clinorotation. We first differentiated mouse embryonic stem cells into cystic EBs containing two germ layers and then analyzed vessel formation under clinorotation...
November 7, 2017: Stem Cell Research
https://www.readbyqxmd.com/read/29141223/gradients-of-rac1-nanoclusters-support-spatial-patterns-of-rac1-signaling
#6
Amanda Remorino, Simon De Beco, Fanny Cayrac, Fahima Di Federico, Gaetan Cornilleau, Alexis Gautreau, Maria Carla Parrini, Jean-Baptiste Masson, Maxime Dahan, Mathieu Coppey
Rac1 is a small RhoGTPase switch that orchestrates actin branching in space and time and protrusion/retraction cycles of the lamellipodia at the cell front during mesenchymal migration. Biosensor imaging has revealed a graded concentration of active GTP-loaded Rac1 in protruding regions of the cell. Here, using single-molecule imaging and super-resolution microscopy, we show an additional supramolecular organization of Rac1. We find that Rac1 partitions and is immobilized into nanoclusters of 50-100 molecules each...
November 14, 2017: Cell Reports
https://www.readbyqxmd.com/read/29136506/a-paradoxical-tumor-suppressor-role-for-the-rac1-exchange-factor-vav1-in-t-cell-acute-lymphoblastic-leukemia
#7
Javier Robles-Valero, L Francisco Lorenzo-Martín, Mauricio Menacho-Márquez, Isabel Fernández-Pisonero, Antonio Abad, Mireia Camós, María L Toribio, Lluis Espinosa, Anna Bigas, Xosé R Bustelo
Rho guanine exchange factors (GEFs), the enzymes that stimulate Rho GTPases, are deemed as potential therapeutic targets owing to their protumorigenic functions. However, the understanding of the spectrum of their pathobiological roles in tumors is still very limited. We report here that the GEF Vav1 unexpectedly possesses tumor-suppressor functions in immature T cells. This function entails the noncatalytic nucleation of complexes between the ubiquitin ligase Cbl-b and the intracellular domain of Notch1 (ICN1) that favors ICN1 ubiquitinylation and degradation...
November 13, 2017: Cancer Cell
https://www.readbyqxmd.com/read/29133526/involvement-of-g%C3%AE-%C3%AE-subunits-of-gi-protein-coupled-with-s1p-receptor-on-multivesicular-endosomes-in-f-actin-formation-and-cargo-sorting-into-exosomes
#8
Taketoshi Kajimoto, Nesma Nabil Ibrahim Mohamed, Shaymaa Mohamed Mohamed Badawy, Shubi Ambwene Matovelo, Mitsuhiro Hirase, Shunsuke Nakamura, Daisuke Yoshida, Taro Okada, Takeshi Ijuin, Shun-Ichi Nakamura
Exosomes play a critical role in cell-to-cell communication by delivering cargo molecules to recipient cells. However, the mechanism underlying the generation of the exosomal multivesicular endosome (MVE) is one of the mysteries in the field of endosome research. Although sphingolipid metabolites such as ceramide and sphingosine 1-phosphate (S1P) are known to play important roles in MVE formation and maturation, the detailed molecular mechanisms are still unclear. Here, we show that Rho family GTPases, including Cdc42 and Rac1, are constitutively activated on exosomal MVEs and are regulated by S1P signaling as measured by fluorescence resonance energy transfer (FRET)-based conformational changes...
November 13, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29133163/non-visual-arrestins-regulate-the-focal-adhesion-formation-via-small-gtpases-rhoa-and-rac1-independently-of-gpcrs
#9
Whitney M Cleghorn, Nada Bulus, Seunghyi Kook, Vsevolod V Gurevich, Roy Zent, Eugenia V Gurevich
Arrestins recruit a variety of signaling proteins to active phosphorylated G protein-coupled receptors in the plasma membrane and to the cytoskeleton. Loss of arrestins leads to decreased cell migration, altered cell shape, and an increase in focal adhesions. Small GTPases of the Rho family are molecular switches that regulate actin cytoskeleton and affect a variety of dynamic cellular functions including cell migration and cell morphology. Here we show that non-visual arrestins differentially regulate RhoA and Rac1 activity to promote cell spreading via actin reorganization, and focal adhesion formation via two distinct mechanisms...
November 11, 2017: Cellular Signalling
https://www.readbyqxmd.com/read/29130632/dock3-related-neurodevelopmental-syndrome-biallelic-intragenic-deletion-of-dock3-in-a-boy-with-developmental-delay-and-hypotonia
#10
Aiko Iwata-Otsubo, Alyssa L Ritter, Brooke Weckselbatt, Nicole R Ryan, David Burgess, Laura K Conlin, Kosuke Izumi
Dedicator of cytokinesis (DOCK) family are evolutionary conserved guanine nucleotide exchange factors (GEFs) for the Rho GTPases, Rac, and Cdc42. DOCK3 functions as a GEF for Rac1, and plays an important role in promoting neurite and axonal growth by stimulating actin dynamics and microtubule assembly pathways in the central nervous system. Here we report a boy with developmental delay, hypotonia, and ataxia due to biallelic DOCK3 deletion. Chromosomal single nucleotide polymorphism (SNP) microarray analysis detected a 170 kb homozygous deletion including exons 6-12 of the DOCK3 gene at 3p21...
November 12, 2017: American Journal of Medical Genetics. Part A
https://www.readbyqxmd.com/read/29129599/itk-and-rlk-inhibitor-prn694-improves-skin-disease-in-two-mouse-models-of-psoriasis
#11
Jessica M Fuhriman, Mårten C G Winge, Helena Haberstock-Debic, Jens Oliver Funk, J Michael Bradshaw, M Peter Marinkovich
The chronic and highly prevalent skin disorder psoriasis vulgaris is characterized by a hyperproliferative epidermis and aberrant immune activity. Many studies have highlighted the role of differentiated T lymphocytes in psoriasis progression. Several biologics are currently available that target pro-inflammatory cytokines produced by T-lymphocytes, but the need for improved therapies persists. The small molecule PRN694 covalently binds ITK and RLK, two TEC kinases activated downstream of T lymphocyte activation, both of which are upregulated in psoriatic skin...
November 9, 2017: Journal of Investigative Dermatology
https://www.readbyqxmd.com/read/29129556/mechanisms-of-rhoa-inactivation-and-cdc42-and-rac1-activation-during-zebrafish-optic-nerve-regeneration
#12
Toru Matsukawa, Kazune Morita, Shou Omizu, Satoru Kato, Yoshiki Koriyama
When axons of the mammalian central nervous system (CNS) are injured, they fail to regenerate, while those of lower vertebrates undergo regeneration after injury. Wingless-type MMTV integration site family (Wnt) proteins play important roles in the CNS, and are reported to be activated after mammalian spinal cord or brain injury. Moreover, for axon growth to proceed, it is thought that small G-proteins, such as CDC42 and Rac1, need to be activated, whereas RhoA must be inactivated. However, the cell and molecular mechanisms involved in optic nerve regeneration remain unclear...
November 10, 2017: Neurochemistry International
https://www.readbyqxmd.com/read/29129468/inhibition-of-rac1-ameliorates-neuronal-oxidative-stress-damage-via-reducing-bcl-2-rac1-complex-formation-in-mitochondria-through-pi3k-akt-mtor-pathway
#13
Yundan Pan, Na Wang, Pingping Xia, E Wang, Qulian Guo, Zhi Ye
Although the neuroprotective effects of Rac1 inhibition have been reported in various cerebral ischemic models, the molecular mechanisms of action have not yet been fully elucidated. In this study, we investigated whether the inhibition of Rac1 provided neuroprotection in a diabetic rat model of focal cerebral ischemia and hyperglycemia-exposed PC-12 cells. Intracerebroventricular administration of lentivirus expressing the Rac1 small hairpin RNA (shRNA) and specific Rac1 inhibitor NSC23766 not only decreased the infarct volumes and improved neurologic deficits with a correlated significant activation of mitochondrial DNA specific proteins, such as OGG1 and POLG, but also elevated Bcl-2 S70 phosphorylation in mitochondria...
November 10, 2017: Experimental Neurology
https://www.readbyqxmd.com/read/29128904/pharmacological-rescue-of-hippocampal-fear-learning-deficits-in-fragile-x-syndrome
#14
Luis A Martinez, Maria Victoria Tejada-Simon
Fragile X Syndrome (FXS) is the leading cause of autism spectrum disorder and intellectual disability and results from loss of Fragile X mental retardation protein (FMRP). In neurons, FMRP controls the translation of synaptic plasticity proteins that are implicated in learning and memory. FMRP also regulates development- and experience-dependent actin cytoskeleton remodeling within dendritic spines through the small Rho GTPase Rac1. Modulation of Rac1 activity is critical during synaptic plasticity as well as learning and memory...
November 11, 2017: Molecular Neurobiology
https://www.readbyqxmd.com/read/29127148/ubc9-binds-to-adap-and-is-required-for-rap1-membrane-recruitment-rac1-activation-and-integrin-mediated-t-cell-adhesion
#15
Yiwei Xiong, Chengjin Ye, Naiqi Yang, Madanqi Li, Hebin Liu
Although the immune adaptor adhesion and degranulation-promoting adaptor protein (ADAP) acts as a key mediator of integrin inside-out signaling leading to T cell adhesion, the regulation of this adaptor during integrin activation and clustering remains unclear. We now identify Ubc9, the sole small ubiquitin-related modifier E2 conjugase, as an essential regulator of ADAP where it is required for TCR-induced membrane recruitment of the small GTPase Rap1 and its effector protein RapL and for activation of the small GTPase Rac1 in T cell adhesion...
November 10, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/29124783/a-key-role-for-rac-and-pak-signaling-in-neutrophil-extracellular-traps-nets-formation-defines-a-new-potential-therapeutic-target
#16
M Gavillet, K Martinod, R Renella, D D Wagner, D A Williams
NET formation in mice (NETosis) is supported by reactive oxygen species (ROS) production by NADPH oxidase and histone hypercitrullination by peptidylarginine deiminase 4 (PAD4). Rac1 and Rac2, expressed in polymorphonuclear neutrophils (PMNs), regulate the cytoskeleton, cell shape, adhesion and migration and are also essential components of the NADPH oxidase complex. We aimed to explore the role of the Rac signaling pathway including the upstream guanosine exchange factor (GEF) activator, Vav, and a downstream effector, the p21-activated kinase, Pak, on NETosis in PMNs using a previously described flow-cytometry-based assay...
November 10, 2017: American Journal of Hematology
https://www.readbyqxmd.com/read/29121646/the-phosphomimetic-mutation-of-syndecan-4-binds-and-inhibits-tiam1-modulating-rac1-activity-in-pdz-interaction-dependent-manner
#17
Aniko Keller-Pinter, Bettina Ughy, Monika Domoki, Aladar Pettko-Szandtner, Tamas Letoha, Jozsef Tovari, Jozsef Timar, Laszlo Szilak
The small GTPases of the Rho family comprising RhoA, Rac1 and Cdc42 function as molecular switches controlling several essential biochemical pathways in eukaryotic cells. Their activity is cycling between an active GTP-bound and an inactive GDP-bound conformation. The exchange of GDP to GTP is catalyzed by guanine nucleotide exchange factors (GEFs). Here we report a novel regulatory mechanism of Rac1 activity, which is controlled by a phosphomimetic (Ser179Glu) mutant of syndecan-4 (SDC4). SDC4 is a ubiquitously expressed transmembrane, heparan sulfate proteoglycan...
2017: PloS One
https://www.readbyqxmd.com/read/29115617/three-dimensional-hydrogel-is-suitable-for-targeted-investigation-of-amoeboid-migration-of-glioma-cells
#18
Yubao Huang, Luqing Tong, Li Yi, Chen Zhang, Long Hai, Tao Li, Shengping Yu, Wei Wang, Zhennan Tao, Haiwen Ma, Peidong Liu, Yang Xie, Xuejun Yang
Glioblastoma (GBM) invasion and migration are key biological behaviors leading to refractoriness to current therapies and infiltration into the non‑tumor brain parenchyma. GBM cell migration is strongly dependent on tumor architecture in vivo, which is absent in traditional two‑dimensional (2D) monolayer culture. The present study applied a three‑dimensional (3D) hydrogel model to rebuild the tumor architecture in vitro. Treatment with NSC23766, a specific inhibitor of Ras‑related C3 botulinum toxin substrate 1 (Rac1), inhibited the mesenchymal invasiveness however triggered the amoeboid motility called mesenchymal‑amoeboid transition (MAT)...
October 26, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/29114077/the-ubiquitin-e3-ligase-traf6-exacerbates-ischemic-stroke-by-ubiquitinating-and-activating-rac1
#19
Tao Li, Juan-Juan Qin, Xia Yang, Yan-Xiao Ji, Fangliang Guo, Wen-Lin Cheng, Xiaolin Wu, Fu-Han Gong, Ying Hong, Xue-Yong Zhu, Jun Gong, Zhihua Wang, Zan Huang, Zhi-Gang She, Hongliang Li
Stroke is one of the leading causes of morbidity and mortality worldwide. Inflammation, oxidative stress, apoptosis, and excitotoxicity contribute to neuronal death during ischemic stroke; however, the mechanisms underlying these complicated pathophysiological processes remain to be fully elucidated. Here, we found that the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6) was markedly increased after cerebral ischemia/reperfusion (I/R) in mice. TRAF6 ablation in male mice decreased the infarct volume and neurological deficit scores, and decreased pro-inflammatory signaling, oxidative stress and neuronal death after cerebral I/R, whereas transgenic overexpression of TRAF6 in male mice exhibited opposite effects...
November 7, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29114038/aberrant-rac1-cofilin-signaling-mediates-defects-in-dendritic-spines-synaptic-function-and-sensory-perception-in-fragile-x-syndrome
#20
Alexander Pyronneau, Qionger He, Jee-Yeon Hwang, Morgan Porch, Anis Contractor, R Suzanne Zukin
Fragile X syndrome (FXS) is the most common inherited cause of intellectual disabilities and a leading cause of autism. FXS is caused by a trinucleotide expansion in the gene FMR1 on the X chromosome. The neuroanatomical hallmark of FXS is an overabundance of immature dendritic spines, a factor thought to underlie synaptic dysfunction and impaired cognition. We showed that aberrantly increased activity of the Rho GTPase Rac1 inhibited the actin-depolymerizing factor cofilin, a major determinant of dendritic spine structure, and caused disease-associated spine abnormalities in the somatosensory cortex of FXS model mice...
November 7, 2017: Science Signaling
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