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https://www.readbyqxmd.com/read/28585695/the-rhogap-myo9b-promotes-bone-growth-by-mediating-osteoblastic-responsiveness-to-igf-1
#1
Brooke K McMichael, Yong-Hoon Jeong, Justin A Auerbach, Cheol-Min Han, Ryan Sedlar, Vikram Shettigar, Martin Bähler, Sudha Agarwal, Do-Gyoon Kim, Beth S Lee
The RhoA subfamily of Rho GTPases regulates actin-based cellular functions in bone such as differentiation, migration, and mechanotransduction. Polymorphisms or genetic ablation of RHOA and some of its regulatory guanine exchange factors (GEFs) have been linked to poor bone health in humans and mice, but the effects of RhoA-specific GTPase-activating proteins (GAPs) on bone quality have not yet been identified. Therefore, we examined the consequences of RhoGAP Myo9b gene knockout on bone growth, phenotype and cellular activity...
June 6, 2017: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/28554775/zonula-occludens-2-regulates-rho-proteins-activity-and-the-development-of-epithelial-cytoarchitecture-and-barrier-function
#2
Arturo Raya-Sandino, Alejandro Castillo-Kauil, Alaide Domínguez-Calderón, Lourdes Alarcón, David Flores-Benitez, Francisco Cuellar-Perez, Bruno López-Bayghen, Bibiana Chávez-Munguía, José Vázquez-Prado, Lorenza González-Mariscal
Silencing Zonula occludens 2 (ZO-2), a tight junctions (TJ) scaffold protein, in epithelial cells (MDCK ZO-2 KD) triggers: 1) Decreased cell to substratum attachment, accompanied by reduced expression of claudin-7 and integrin β1, and increased vinculin recruitment to focal adhesions and stress fibers formation; 2) Lowered cell-cell aggregation and appearance of wider intercellular spaces; 3) Increased RhoA/ROCK activity, mediated by GEF-HI recruitment to cell borders by cingulin; 4) Increased Cdc42 activity, mitotic spindle disorientation and the appearance of cysts with multiple lumens; 5) Increased Rac and cofilin activity, multiple lamellipodia formation and random cell migration but increased wound closure; 6) Diminished cingulin phosphorylation and disappearance of planar network of microtubules at the TJ region; and 7) Increased transepithelial electrical resistance at steady state, coupled to an increased expression of ZO-1 and claudin-4 and a decreased expression of claudin-2 and paracingulin...
May 26, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28539404/analysis-of-interphase-node-proteins-in-fission-yeast-by-quantitative-and-super-resolution-fluorescence-microscopy
#3
Matthew Akamatsu, Yu Lin, Joerg Bewersdorf, Thomas D Pollard
We used quantitative confocal microscopy and FPALM super resolution microscopy of live fission yeast to investigate the structures and assembly of two types of interphase nodes, multiprotein complexes associated with the plasma membrane that merge together and mature into the precursors of the cytokinetic contractile ring. During the long G2 phase of the cell cycle seven different interphase node proteins maintain constant concentrations as they accumulate in proportion to cell volume. During mitosis the total numbers of type 1 node proteins (cell cycle kinases Cdr1p, Cdr2p, Wee1p, and anillin Mid1p) are constant even when the nodes disassemble...
May 24, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28521592/molecular-perturbation-strategies-to-examine-spatiotemporal-features-of-rho-gef-and-rho-gtpase-activity-in-living-cells
#4
Joachim Goedhart, Jakobus van Unen
Much of our current knowledge of Rho GTPase networks and the regulation by Rho guanine exchange factors (Rho GEFs) and Rho GTPase activating proteins (Rho GAPs) is based on population-based techniques. Over the last decades, technologies that enable single cell analysis with high spatial and temporal resolution have revealed that Rho GTPase activity in cells is regulated on second timescales and at submicrometer length scales. Therefore, perturbation methods with matching spatial and temporal resolution are crucial to further our understanding of Rho GTPase signaling...
May 19, 2017: Small GTPases
https://www.readbyqxmd.com/read/28512143/diverse-roles-of-guanine-nucleotide-exchange-factors-in-regulating-collective-cell-migration
#5
Assaf Zaritsky, Yun-Yu Tseng, M Angeles Rabadán, Shefali Krishna, Michael Overholtzer, Gaudenz Danuser, Alan Hall
Efficient collective migration depends on a balance between contractility and cytoskeletal rearrangements, adhesion, and mechanical cell-cell communication, all controlled by GTPases of the RHO family. By comprehensive screening of guanine nucleotide exchange factors (GEFs) in human bronchial epithelial cell monolayers, we identified GEFs that are required for collective migration at large, such as SOS1 and β-PIX, and RHOA GEFs that are implicated in intercellular communication. Down-regulation of the latter GEFs differentially enhanced front-to-back propagation of guidance cues through the monolayer and was mirrored by down-regulation of RHOA expression and myosin II activity...
June 5, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28489960/swap70-is-a-universal-gef-like-adapter-for-tethering-actin-to-phagosomes
#6
Maksim V Baranov, Natalia H Revelo, Daniëlle R J Verboogen, Martin Ter Beest, Geert van den Bogaart
We recently identified a key role for SWAP70 as the tethering factor stabilizing F-actin filaments on the surface of phagosomes in human dendritic cells by interacting both with Rho-family GTPases and the lipid phosphatidylinositol (3,4)-bisphosphate. In this study, we aimed to investigate whether this role of SWAP70 was general among immune phagocytes. Our data reveal that SWAP70 is recruited to early phagosomes of macrophages and dendritic cells from both human and mouse. The putative inhibitor of SWAP70 sanguinarine blocked phagocytosis and F-actin polymerization, supporting a key role for SWAP70 in phagocytosis as demonstrated previously with knock-down...
May 10, 2017: Small GTPases
https://www.readbyqxmd.com/read/28472098/t1r3-homomeric-sweet-taste-receptor-regulates-adipogenesis-through-g%C3%AE-s-mediated-microtubules-disassembly-and-rho-activation-in-3t3-l1-cells
#7
Yosuke Masubuchi, Yuko Nakagawa, Johan Medina, Masahiro Nagasawa, Itaru Kojima, Mark M Rasenick, Takeshi Inagaki, Hiroshi Shibata
We previously reported that 3T3-L1 cells express a functional sweet taste receptor possibly as a T1R3 homomer that is coupled to Gs and negatively regulates adipogenesis by a Gαs-mediated but cAMP-independent mechanism. Here, we show that stimulation of this receptor with sucralose or saccharin induced disassembly of the microtubules in 3T3-L1 preadipocytes, which was attenuated by overexpression of the dominant-negative mutant of Gαs (Gαs-G226A). In contrast, overexpression of the constitutively active mutant of Gαs (Gαs-Q227L) as well as treatment with cholera toxin or isoproterenol but not with forskolin caused disassembly of the microtubules...
2017: PloS One
https://www.readbyqxmd.com/read/28418645/brain-region-and-isoform-specific-phosphorylation-alters-kalirin-sh2-domain-interaction-sites-and-calpain-sensitivity
#8
Megan B Miller, Yan Yan, Kazuya Machida, Drew D Kiraly, Aaron D Levy, Yi I Wu, TuKiet T Lam, Thomas Abbott, Anthony J Koleske, Betty A Eipper, Richard E Mains
Kalirin7 (Kal7), a postsynaptic Rho GDP/GTP exchange factor (RhoGEF), plays a crucial role in long-term potentiation and in the effects of cocaine on behavior and spine morphology. The KALRN gene has been linked to schizophrenia and other disorders of synaptic function. Mass spectrometry was used to quantify phosphorylation at 26 sites in Kal7 from individual adult rat nucleus accumbens and prefrontal cortex before and after exposure to acute or chronic cocaine. Region- and isoform-specific phosphorylation was observed along with region-specific effects of cocaine on Kal7 phosphorylation...
April 25, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28389580/the-mgcracgap-sxip-motif-tethers-centralspindlin-to-microtubule-plus-ends-in-xenopus-laevis
#9
Elaina B Breznau, Megan Murt, T Lynne Blasius, Kristen J Verhey, Ann L Miller
Centralspindlin, a complex of the kinesin-6-family member MKLP1 and MgcRacGAP (also known as Kif23 and Racgap1, respectively), is required for cytokinesis and cell-cell junctions. During anaphase, Centralspindlin accumulates at overlapping central spindle microtubules and directs contractile ring formation by recruiting the GEF Ect2 to the cell equator to activate RhoA. We found that MgcRacGAP localized to the plus ends of equatorial astral microtubules during cytokinesis in Xenopus laevis embryos. How MgcRacGAP is stabilized at microtubule plus ends is unknown...
May 15, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28356423/phosphorylated-cortactin-recruits-vav2-guanine-nucleotide-exchange-factor-to-activate-rac3-and-promote-invadopodial-function-in-invasive-breast-cancer-cells
#10
Brian J Rosenberg, Hava Gil-Henn, Christopher C Mader, Tiffany Halo, Taofei Yin, John Condeelis, Kazuya Machida, Yi I Wu, Anthony J Koleske
Breast carcinoma cells use specialized, actin-rich protrusions called invadopodia to degrade and invade through the extracellular matrix. Phosphorylation of the actin nucleation-promoting factor and actin-stabilizing protein cortactin downstream of the epidermal growth factor receptor-Src-Arg kinase cascade is known to be a critical trigger for invadopodium maturation and subsequent cell invasion in breast cancer cells. The functions of cortactin phosphorylation in this process, however, are not completely understood...
May 15, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28334931/rgf1p-rho1p-gef-is-required-for-double-strand-break-repair-in-fission-yeast
#11
Elvira Manjón, Tomás Edreira, Sofía Muñoz, Yolanda Sánchez
Rho GTPases are conserved molecules that control cytoskeletal dynamics. These functions are expedited by Rho GEFs that stimulate the release of GDP to enable GTP binding, thereby allowing Rho proteins to initiate intracellular signaling. How Rho GEFs and Rho GTPases protect cells from DNA damage is unknown. Here, we explore the extreme sensitivity of a deletion mutation in the Rho1p exchange factor Rgf1p to the DNA break/inducing antibiotic phleomycin (Phl). The Rgf1p mutant cells are defective in reentry into the cell cycle following the induction of severe DNA damage...
May 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28304230/modular-regulation-of-rho-family-gtpases-in-development
#12
Marlis Denk-Lobnig, Adam C Martin
Rho family GTPase signaling regulates the actin cytoskeleton and is critical for behaviors that range from the cell to tissue-scale. A theme in Rho GTPase biology is that there are many more regulators, such as guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), than GTPases themselves. Here, we review different, modular cases where GEFs and GAPs function together to elicit precise spatial and temporal control of signaling. We focus on examples from metazoan development, where precise regulation of Rho GTPases is critical for proper tissue form and function...
March 17, 2017: Small GTPases
https://www.readbyqxmd.com/read/28298491/cyk-4-regulates-rac-but-not-rho-during-cytokinesis
#13
Yelena Zhuravlev, Sophia M Hirsch, Shawn N Jordan, Julien Dumont, Mimi Shirasu-Hiza, Julie C Canman
Cytokinesis is driven by constriction of an actomyosin contractile ring that is controlled by Rho-family small GTPases. Rho, activated by the guanine-nucleotide exchange factor ECT-2, is upstream of both myosin-II activation and diaphanous formin-mediated filamentous actin (f-actin) assembly, which drive ring constriction. The role for Rac and its regulators is more controversial, but, based on the finding that Rac inactivation can rescue cytokinesis failure when the GTPase-activating protein (GAP) CYK-4 is disrupted, Rac activity was proposed to be inhibitory to contractile ring constriction and thus specifically inactivated by CYK-4 at the division plane...
May 1, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28287334/regulation-of-rho-gtpase-activity-at-the-leading-edge-of-migrating-cells-by-p190rhogap
#14
Aurélien Bidaud-Meynard, Fabien Binamé, Valérie Lagrée, Violaine Moreau
Cell migration, a key feature of embryonic development, immunity, angiogenesis, and tumor metastasis, is based on the coordinated regulation of actin dynamics and integrin-mediated adhesion. Rho GTPases play a major role in this phenomenon by regulating the onset and maintenance of actin-based protruding structures at cell leading edges (i.e. lamellipodia and filopodia) and contractile structures (i.e., stress fibers) at their trailing edge. While spatio-temporal analysis demonstrated the tight regulation of Rho GTPases at the migration front during cell locomotion, little is known about how the main regulators of Rho GTPase activity, such as GAPs, GEFs and GDIs, play a role in this process...
March 13, 2017: Small GTPases
https://www.readbyqxmd.com/read/28196833/characterization-of-the-activation-of-small-gtpases-by-their-gefs-on-membranes-using-artificial-membrane-tethering
#15
François Peurois, Simon Veyron, Yann Ferrandez, Ilham Ladid, Sarah Benabdi, Mahel Zeghouf, Gérald Peyroche, Jacqueline Cherfils
Active, GTP-bound small GTPases need to be attached to membranes by post-translational lipid modifications in order to process and propagate information in cells. However, generating and manipulating lipidated GTPases has remained difficult, which has limited our quantitative understanding of their activation by guanine nucleotide exchange factors (GEFs) and their termination by GTPase-activating proteins. Here, we replaced the lipid modification by a histidine tag in 11 full-length, human small GTPases belonging to the Arf, Rho and Rab families, which allowed to tether them to nickel-lipid-containing membranes and characterize the kinetics of their activation by GEFs...
March 23, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28188273/the-ropgef2-rop7-rop2-pathway-activated-by-phyb-suppresses-red-light-induced-stomatal-opening
#16
Wei Wang, Zhao Liu, Li-Juan Bao, Sha-Sha Zhang, Chun-Guang Zhang, Xin Li, Hai-Xia Li, Xiao-Lu Zhang, Atle Magnar Bones, Zhen-Biao Yang, Yu-Ling Chen
Circadian rhythm of stomatal aperture is mainly regulated by light/darkness. Blue and red light induce stomatal opening through different mechanisms that are mediated by special receptors. ROP2, a member of Rho GTPase family in Arabidopsis (Arabidopsisthaliana), has been found to negatively regulate light-induced stomatal opening. However, the upstream guanine nucleotide exchange factor (GEF) RopGEFs have not been revealed, and it is unclear which photoreceptor is required for the action of RopGEFs-ROPs. Here, we showed that RopGEF2 acted as a negative regulator in phytochrome B (phyB)-mediated red light-induced stomatal opening...
June 2017: Plant Physiology
https://www.readbyqxmd.com/read/28130497/mechanisms-of-impaired-neutrophil-migration-by-micrornas-in-myelodysplastic-syndromes
#17
Meiwan Cao, Yayoi Shikama, Hideo Kimura, Hideyoshi Noji, Kazuhiko Ikeda, Tomoyuki Ono, Kazuei Ogawa, Yasuchika Takeishi, Junko Kimura
In myelodysplastic syndromes (MDS), functional defects of neutrophils result in high mortality because of infections; however, the molecular basis remains unclear. We recently found that miR-34a and miR-155 were significantly increased in MDS neutrophils. To clarify the effects of the aberrant microRNA expression on neutrophil functions, we introduced miR-34a, miR-155, or control microRNA into neutrophil-like differentiated HL60 cells. Ectopically introduced miR-34a and miR-155 significantly attenuated migration toward chemoattractants fMLF and IL-8, but enhanced degranulation...
January 27, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/28115158/mdia2-and-cxcl12-cxcr4-chemokine-signaling-intersect-to-drive-tumor-cell-amoeboid-morphological-transitions
#18
Meghan M Wyse, Silvia Goicoechea, Rafael Garcia-Mata, Andrea L Nestor-Kalinoski, Kathryn M Eisenmann
Morphological plasticity in response to environmental cues in migrating cancer cells requires F-actin cytoskeletal rearrangements. Conserved formin family proteins play critical roles in cell shape, tumor cell motility, invasion and metastasis, in part, through assembly of non-branched actin filaments. Diaphanous-related formin-2 (mDia2/Diaph3/Drf3/Dia) regulates mesenchymal-to-amoeboid morphological conversions and non-apoptotic blebbing in tumor cells by interacting with its inhibitor diaphanous-interacting protein (DIP), and disrupting cortical F-actin assembly and bundling...
March 4, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28108261/heterotrimeric-g-protein-g%C3%AE-s-subunit-attenuates-plekhg2-a-rho-family-specific-guanine-nucleotide-exchange-factor-by-direct-interaction
#19
Kazue Sugiyama, Kenji Tago, Sayumi Matsushita, Masashi Nishikawa, Katsuya Sato, Yoshinori Muto, Takahiro Nagase, Hiroshi Ueda
PLEKHG2 is a Gβγ-dependent guanine nucleotide exchange factor (GEF) for the small GTPases Rac and Cdc42, and has been shown to mediate signalling pathways such as actin cytoskeleton reorganization and serum response element (SRE)-dependent gene transcription. Here we show that the constitutively active mutant of the Gαs subunit significantly attenuated PLEKHG2-induced SRE-mediated gene transcription. Strikingly, we observed that the constitutive activation of endogenous Gαs by treatment with CTx caused a similar inhibitory effect on PLEKHG2-induced activation of SRE...
January 17, 2017: Cellular Signalling
https://www.readbyqxmd.com/read/28065575/multiparametric-analysis-of-cell-shape-demonstrates-that-%C3%AE-pix-directly-couples-yap-activation-to-extracellular-matrix-adhesion
#20
Julia E Sero, Chris Bakal
Mechanical signals from the extracellular matrix (ECM) and cellular geometry regulate the nuclear translocation of transcriptional regulators such as Yes-associated protein (YAP). Elucidating how physical signals control the activity of mechanosensitive proteins poses a technical challenge, because perturbations that affect cell shape may also affect protein localization indirectly. Here, we present an approach that mitigates confounding effects of cell-shape changes, allowing us to identify direct regulators of YAP localization...
January 25, 2017: Cell Systems
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