Correction: The dynein adaptor Hook2 plays essential roles in mitotic progression and cytokinesis
Vol. 218, No. 3, March 4, 2019. 10.1083/jcb.201804183. The authors were recently alerted that some of the blot images used to generate Fig. 2 E were inaccurate and similar to images shown in Fig. 1... (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Dwivedi, D., Kumari, A., Rathi, S., Mylavarapu, S. V. S., Sharma, M. Tags: Corrections Source Type: research

Perlecan regulates pericyte dynamics in the maintenance and repair of the blood-brain barrier
Ischemic stroke causes blood–brain barrier (BBB) breakdown due to significant damage to the integrity of BBB components. Recent studies have highlighted the importance of pericytes in the repair process of BBB functions triggered by PDGFRβ up-regulation. Here, we show that perlecan, a major heparan sulfate proteoglycan of basement membranes, aids in BBB maintenance and repair through pericyte interactions. Using a transient middle cerebral artery occlusion model, we found larger infarct volumes and more BBB leakage in conditional perlecan (Hspg2)-deficient (Hspg2–/–-TG) mice than in control mice. Con...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Nakamura, K., Ikeuchi, T., Nara, K., Rhodes, C. S., Zhang, P., Chiba, Y., Kazuno, S., Miura, Y., Ago, T., Arikawa-Hirasawa, E., Mukouyama, Y.-s., Yamada, Y. Tags: Disease, Cell Signaling, Migration, Motility, Neuroscience Articles Source Type: research

Phosphorylation of CEP83 by TTBK2 is necessary for cilia initiation
Primary cilia are microtubule-based organelles that play important roles in development and tissue homeostasis. Tau-tubulin kinase-2 (TTBK2) is genetically linked to spinocerebellar ataxia type 11, and its kinase activity is crucial for ciliogenesis. Although it has been shown that TTBK2 is recruited to the centriole by distal appendage protein CEP164, little is known about TTBK2 substrates associated with its role in ciliogenesis. Here, we perform superresolution microscopy and discover that serum starvation results in TTBK2 redistribution from the periphery toward the root of distal appendages. Our biochemical analyses u...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Lo, C.-H., Lin, I.-H., Yang, T. T., Huang, Y.-C., Tanos, B. E., Chou, P.-C., Chang, C.-W., Tsay, Y.-G., Liao, J.-C., Wang, W.-J. Tags: Cilia, Development Articles Source Type: research

YAP and TAZ regulate cell volume
How mammalian cells regulate their physical size is currently poorly understood, in part due to the difficulty in accurately quantifying cell volume in a high-throughput manner. Here, using the fluorescence exclusion method, we demonstrate that the mechanosensitive transcriptional regulators YAP (Yes-associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif) are regulators of single-cell volume. The role of YAP/TAZ in volume regulation must go beyond its influence on total cell cycle duration or cell shape to explain the observed changes in volume. Moreover, for our experimental conditions, volume reg...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Perez-Gonzalez, N. A., Rochman, N. D., Yao, K., Tao, J., Le, M.-T. T., Flanary, S., Sablich, L., Toler, B., Crentsil, E., Takaesu, F., Lambrus, B., Huang, J., Fu, V., Chengappa, P., Jones, T. M., Holland, A. J., An, S., Wirtz, D., Petrie, R. J., Guan, K.- Tags: Cell Cycle and Division, Biophysics, Systems and Computational Biology Articles Source Type: research

Gulp1 controls Eph/ephrin trogocytosis and is important for cell rearrangements during development
Trogocytosis, in which cells nibble away parts of neighboring cells, is an intercellular cannibalism process conserved from protozoa to mammals. Its underlying molecular mechanisms are not well understood and are likely distinct from phagocytosis, a process that clears entire cells. Bi-directional contact repulsion induced by Eph/ephrin signaling involves transfer of membrane patches and full-length Eph/ephrin protein complexes between opposing cells, resembling trogocytosis. Here, we show that the phagocytic adaptor protein Gulp1 regulates EphB/ephrinB trogocytosis to achieve efficient cell rearrangements of cultured cell...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Gong, J., Gaitanos, T. N., Luu, O., Huang, Y., Gaitanos, L., Lindner, J., Winklbauer, R., Klein, R. Tags: Cell Signaling, Trafficking, Biochemistry, Development Articles Source Type: research

A kindlin-3-leupaxin-paxillin signaling pathway regulates podosome stability
In conclusion, our findings show that kindlin-3 not only activates and clusters integrins into podosomes but also regulates their lifetime by recruiting leupaxin, which controls PTP-PEST activity and thereby paxillin phosphorylation and downstream signaling. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Klapproth, S., Bromberger, T., Türk, C., Krüger, M., Moser, M. Tags: Adhesion, Cell Signaling, Biochemistry Articles Source Type: research

The role of APC-mediated actin assembly in microtubule capture and focal adhesion turnover
Focal adhesion (FA) turnover depends on microtubules and actin. Microtubule ends are captured at FAs, where they induce rapid FA disassembly. However, actin’s roles are less clear. Here, we use polarization-resolved microscopy, FRAP, live cell imaging, and a mutant of Adenomatous polyposis coli (APC-m4) defective in actin nucleation to investigate the role of actin assembly in FA turnover. We show that APC-mediated actin assembly is critical for maintaining normal F-actin levels, organization, and dynamics at FAs, along with organization of FA components. In WT cells, microtubules are captured repeatedly at FAs as th...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Juanes, M. A., Isnardon, D., Badache, A., Brasselet, S., Mavrakis, M., Goode, B. L. Tags: Cytoskeleton, Genetics Articles Source Type: research

Apical polarity proteins recruit the RhoGEF Cysts to promote junctional myosin assembly
The spatio-temporal regulation of small Rho GTPases is crucial for the dynamic stability of epithelial tissues. However, how RhoGTPase activity is controlled during development remains largely unknown. To explore the regulation of Rho GTPases in vivo, we analyzed the Rho GTPase guanine nucleotide exchange factor (RhoGEF) Cysts, the Drosophila orthologue of mammalian p114RhoGEF, GEF-H1, p190RhoGEF, and AKAP-13. Loss of Cysts causes a phenotype that closely resembles the mutant phenotype of the apical polarity regulator Crumbs. This phenotype can be suppressed by the loss of basolateral polarity proteins, suggesting that Cys...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Silver, J. T., Wirtz-Peitz, F., Simoes, S., Pellikka, M., Yan, D., Binari, R., Nishimura, T., Li, Y., Harris, T. J. C., Perrimon, N., Tepass, U. Tags: Cytoskeleton, Development Articles Source Type: research

Claudins and JAM-A coordinately regulate tight junction formation and epithelial polarity
Tight junctions (TJs) establish the epithelial barrier and are thought to form a membrane fence to regulate epithelial polarity, although the roles of TJs in epithelial polarity remain controversial. Claudins constitute TJ strands in conjunction with the cytoplasmic scaffolds ZO-1 and ZO-2 and play pivotal roles in epithelial barrier formation. However, how claudins and other TJ membrane proteins cooperate to organize TJs remains unclear. Here, we systematically knocked out TJ components by genome editing and show that while ZO-1/ZO-2–deficient cells lacked TJ structures and epithelial barriers, claudin-deficient cel...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Otani, T., Nguyen, T. P., Tokuda, S., Sugihara, K., Sugawara, T., Furuse, K., Miura, T., Ebnet, K., Furuse, M. Tags: Adhesion, Physiology Articles Source Type: research

MT1-MMP recruits the ER-Golgi SNARE Bet1 for efficient MT1-MMP transport to the plasma membrane
Metastasis is a major cause of cancer-related death. Membrane type 1–matrix metalloproteinase (MT1-MMP) is a critical protease for local invasion and metastasis. MT1-MMP is synthesized in the endoplasmic reticulum (ER) and transported in vesicles to invadopodia, specialized subdomains of the plasma membrane, through secretory and endocytic recycling pathways. The molecular mechanism underlying intracellular transport of MT1-MMP has been extensively studied, but is not fully understood. We show that MT1-MMP diverts the SNARE Bet1 from its function in ER-Golgi transport, to promote MT1-MMP trafficking to the cell surfa...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Miyagawa, T., Hasegawa, K., Aoki, Y., Watanabe, T., Otagiri, Y., Arasaki, K., Wakana, Y., Asano, K., Tanaka, M., Yamaguchi, H., Tagaya, M., Inoue, H. Tags: Organelles, Membrane and Lipid Biology, Cancer Articles Source Type: research

VPS37A directs ESCRT recruitment for phagophore closure
The process of phagophore closure requires the endosomal sorting complex required for transport III (ESCRT-III) subunit CHMP2A and the AAA ATPase VPS4, but their regulatory mechanisms remain unknown. Here, we establish a FACS-based HaloTag-LC3 autophagosome completion assay to screen a genome-wide CRISPR library and identify the ESCRT-I subunit VPS37A as a critical component for phagophore closure. VPS37A localizes on the phagophore through the N-terminal putative ubiquitin E2 variant domain, which is found to be required for autophagosome completion but dispensable for ESCRT-I complex formation and the degradation of epid...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Takahashi, Y., Liang, X., Hattori, T., Tang, Z., He, H., Chen, H., Liu, X., Abraham, T., Imamura-Kawasawa, Y., Buchkovich, N. J., Young, M. M., Wang, H.-G. Tags: Cell Death and Autophagy, Biochemistry Articles Source Type: research

Lipid droplet size directs lipolysis and lipophagy catabolism in hepatocytes
Lipid droplet (LD) catabolism in hepatocytes is mediated by a combination of lipolysis and a selective autophagic mechanism called lipophagy, but the relative contributions of these seemingly distinct pathways remain unclear. We find that inhibition of lipolysis, lipophagy, or both resulted in similar overall LD content but dramatic differences in LD morphology. Inhibition of the lipolysis enzyme adipose triglyceride lipase (ATGL) resulted in large cytoplasmic LDs, whereas lysosomal inhibition caused the accumulation of numerous small LDs within the cytoplasm and degradative acidic vesicles. Combined inhibition of ATGL and...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Schott, M. B., Weller, S. G., Schulze, R. J., Krueger, E. W., Drizyte-Miller, K., Casey, C. A., McNiven, M. A. Tags: Cell Metabolism, Trafficking, Biochemistry, Metabolism Articles Source Type: research

A molecular recognition feature mediates ribosome-induced SRP-receptor assembly during protein targeting
Molecular recognition features (MoRFs) provide interaction motifs in intrinsically disordered protein regions to mediate diverse cellular functions. Here we report that a MoRF element, located in the disordered linker domain of the mammalian signal recognition particle (SRP) receptor and conserved among eukaryotes, plays an essential role in sensing the ribosome during cotranslational protein targeting to the endoplasmic reticulum. Loss of the MoRF in the SRP receptor (SR) largely abolishes the ability of the ribosome to activate SRP-SR assembly and impairs cotranslational protein targeting. These results demonstrate a nov...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Hwang Fu, Y.-H., Chandrasekar, S., Lee, J. H., Shan, S.-o. Tags: Protein Homeostasis, Biochemistry Articles Source Type: research

FIGNL1 associates with KIF1B{beta} and BICD1 to restrict dynein transport velocity during axon navigation
Neuronal connectivity relies on molecular motor-based axonal transport of diverse cargoes. Yet the precise players and regulatory mechanisms orchestrating such trafficking events remain largely unknown. We here report the ATPase Fignl1 as a novel regulator of bidirectional transport during axon navigation. Using a yeast two-hybrid screen and coimmunoprecipitation assays, we showed that Fignl1 binds the kinesin Kif1bβ and the dynein/dynactin adaptor Bicaudal D-1 (Bicd1) in a molecular complex including the dynactin subunit dynactin 1. Fignl1 colocalized with Kif1bβ and showed bidirectional mobility in zebrafish ax...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Atkins, M., Gasmi, L., Bercier, V., Revenu, C., Del Bene, F., Hazan, J., Fassier, C. Tags: Cytoskeleton, Trafficking, Development, Neuroscience Articles Source Type: research

Cell and tissue morphology determine actin-dependent nuclear migration mechanisms in neuroepithelia
Correct nuclear position is crucial for cellular function and tissue development. Depending on cell context, however, the cytoskeletal elements responsible for nuclear positioning vary. While these cytoskeletal mechanisms have been intensely studied in single cells, how nuclear positioning is linked to tissue morphology is less clear. Here, we compare apical nuclear positioning in zebrafish neuroepithelia. We find that kinetics and actin-dependent mechanisms of nuclear positioning vary in tissues of different morphology. In straight neuroepithelia, nuclear positioning is controlled by Rho-ROCK–dependent myosin contra...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Yanakieva, I., Erzberger, A., Matejcic, M., Modes, C. D., Norden, C. Tags: Cytoskeleton, Organelles, Development Articles Source Type: research

Coronin 1A depletion restores the nuclear stability and viability of Aip1/Wdr1-deficient neutrophils
Actin dynamics is central for cells, and especially for the fast-moving leukocytes. The severing of actin filaments is mainly achieved by cofilin, assisted by Aip1/Wdr1 and coronins. We found that in Wdr1-deficient zebrafish embryos, neutrophils display F-actin cytoplasmic aggregates and a complete spatial uncoupling of phospho-myosin from F-actin. They then undergo an unprecedented gradual disorganization of their nucleus followed by eruptive cell death. Their cofilin is mostly unphosphorylated and associated with F-actin, thus likely outcompeting myosin for F-actin binding. Myosin inhibition reproduces in WT embryos the ...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Bowes, C., Redd, M., Yousfi, M., Tauzin, M., Murayama, E., Herbomel, P. Tags: Disease, Cytoskeleton, Development Articles Source Type: research

Enrichment of Aurora B kinase at the inner kinetochore controls outer kinetochore assembly
Outer kinetochore assembly enables chromosome attachment to microtubules and spindle assembly checkpoint (SAC) signaling in mitosis. Aurora B kinase controls kinetochore assembly by phosphorylating the Mis12 complex (Mis12C) subunit Dsn1. Current models propose Dsn1 phosphorylation relieves autoinhibition, allowing Mis12C binding to inner kinetochore component CENP-C. Using Xenopus laevis egg extracts and biochemical reconstitution, we found that autoinhibition of the Mis12C by Dsn1 impedes its phosphorylation by Aurora B. Our data indicate that the INCENP central region increases Dsn1 phosphorylation by enriching Aurora B...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Bonner, M. K., Haase, J., Swinderman, J., Halas, H., Miller Jenkins, L. M., Kelly, A. E. Tags: Cytoskeleton, Cell Cycle and Division, Biochemistry Articles Source Type: research

Aurora B kinase activity is regulated by SET/TAF1 on Sgo2 at the inner centromere
The accurate regulation of phosphorylation at the kinetochore is essential for establishing chromosome bi-orientation. Phosphorylation of kinetochore proteins by the Aurora B kinase destabilizes improper kinetochore–microtubule attachments, whereas the phosphatase PP2A has a counteracting role. Imbalanced phosphoregulation leads to error-prone chromosome segregation and aneuploidy, a hallmark of cancer cells. However, little is known about the molecular events that control the balance of phosphorylation at the kinetochore. Here, we show that localization of SET/TAF1, an oncogene product, to centromeres maintains Auro...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Asai, Y., Fukuchi, K., Tanno, Y., Koitabashi-Kiyozuka, S., Kiyozuka, T., Noda, Y., Matsumura, R., Koizumi, T., Watanabe, A., Nagata, K., Watanabe, Y., Terada, Y. Tags: Cell Cycle and Division, Cancer Articles Source Type: research

Hair follicle regeneration suppresses Ras-driven oncogenic growth
Mutations associated with tumor development in certain tissues can be nontumorigenic in others, yet the mechanisms underlying these different outcomes remains poorly understood. To address this, we targeted an activating Hras mutation to hair follicle stem cells and discovered that Hras mutant cells outcompete wild-type neighbors yet are integrated into clinically normal skin hair follicles. In contrast, targeting the Hras mutation to the upper noncycling region of the skin epithelium leads to benign outgrowths. Follicular Hras mutant cells autonomously and nonautonomously enhance regeneration, which directs mutant cells i...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Pineda, C. M., Gonzalez, D. G., Matte-Martone, C., Boucher, J., Lathrop, E., Gallini, S., Fons, N. R., Xin, T., Tai, K., Marsh, E., Nguyen, D. X., Suozzi, K. C., Beronja, S., Greco, V. Tags: Stem Cells, Cell Signaling, Cancer Reports Source Type: research

Dynamic instability of clathrin assembly provides proofreading control for endocytosis
Clathrin-mediated endocytosis depends on the formation of functional clathrin-coated pits that recruit cargos and mediate the uptake of those cargos into the cell. However, it remains unclear whether the cargos in the growing clathrin-coated pits are actively monitored by the coat assembly machinery. Using a cell-free reconstitution system, we report that clathrin coat formation and cargo sorting can be uncoupled, indicating that a checkpoint is required for functional cargo incorporation. We demonstrate that the ATPase Hsc70 and a dynamic exchange of clathrin during assembly are required for this checkpoint. In the absenc...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Chen, Y., Yong, J., Martinez-Sanchez, A., Yang, Y., Wu, Y., De Camilli, P., Fernandez-Busnadiego, R., Wu, M. Tags: Membrane and Lipid Biology, Trafficking, Biochemistry, Biophysics Reports Source Type: research

Checkpoint signaling and error correction require regulation of the MPS1 T-loop by PP2A-B56
During mitosis, the formation of microtubule–kinetochore attachments is monitored by the serine/threonine kinase monopolar spindle 1 (MPS1). MPS1 is recruited to unattached kinetochores where it phosphorylates KNL1, BUB1, and MAD1 to initiate the spindle assembly checkpoint. This arrests the cell cycle until all kinetochores have been stably captured by microtubules. MPS1 also contributes to the error correction process rectifying incorrect kinetochore attachments. MPS1 activity at kinetochores requires autophosphorylation at multiple sites including threonine 676 in the activation segment or "T-loop." We n...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Hayward, D., Bancroft, J., Mangat, D., Alfonso-Perez, T., Dugdale, S., McCarthy, J., Barr, F. A., Gruneberg, U. Tags: Cell Cycle and Division Reports Source Type: research

Protein quality control in the secretory pathway
Protein folding is inherently error prone, especially in the endoplasmic reticulum (ER). Even with an elaborate network of molecular chaperones and protein folding facilitators, misfolding can occur quite frequently. To maintain protein homeostasis, eukaryotes have evolved a series of protein quality-control checkpoints. When secretory pathway quality-control pathways fail, stress response pathways, such as the unfolded protein response (UPR), are induced. In addition, the ER, which is the initial hub of protein biogenesis in the secretory pathway, triages misfolded proteins by delivering substrates to the proteasome or to...
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Sun, Z., Brodsky, J. L. Tags: Review Source Type: research

Eph receptors and ephrins engage in cellular cannibalism
Eph receptors bind ephrins on neighboring cells, oligomerizing into adhesive complexes that recruit signaling molecules. Execution of their signature repulsive program then generates pulling forces, enabling a cell to engulf a piece of another cell. New mechanistic insights by Gong et al. (2019. J. Cell Biol. define this process as a form of "cellular cannibalism." (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Pasquale, E. B. Tags: Cell Signaling, Development, Neuroscience Spotlight Source Type: research

Kindlin-3 stokes the life span of podosomes
Macrophages and other cell types can form podosomes, highly dynamic adhesive structures that mediate the interaction of these cells with the surrounding matrix. In this issue, Klapproth et al. (2019. J. Cell Biol. find that kindlin-3 regulates podosome stability by recruiting leupaxin, with concomitant effects on PTP-PEST phosphatase activity and paxillin phosphorylation. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Zhang, H. Tags: Spotlight Source Type: research

Adult hair follicles keep oncogenic growth in check
Recent research shows that potentially cancerous, somatic mutations can reside in normal cells. Pineda et al. (2019. J. Cell Biol. report on a unique management technique by hair follicle stem cells to evade tumorigenesis. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: Gay, D., Ito, M. Tags: Spotlight Source Type: research

Brajendra Tripathi: Keeping an eye out for translational research
Tripathi investigates how the tumor suppressor DLC1 is regulated by oncogenic kinases. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - October 7, 2019 Category: Cytology Authors: ODonnell, M. A. Tags: People & amp;amp; Ideas Source Type: research

Software for lattice light-sheet imaging of FRET biosensors, illustrated with a new Rap1 biosensor
We describe here a new software package, named ImageTank, that is specifically designed for practical imaging of biosensors using LLSM. To demonstrate its capabilities, we use a new biosensor to study the rapid 3D dynamics of the small GTPase Rap1 in vesicles and cell protrusions. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: OShaughnessy, E. C., Stone, O. J., LaFosse, P. K., Azoitei, M. L., Tsygankov, D., Heddleston, J. M., Legant, W. R., Wittchen, E. S., Burridge, K., Elston, T. C., Betzig, E., Chew, T.-L., Adalsteinsson, D., Hahn, K. M. Tags: Cell Signaling, Technology Tools Source Type: research

Metalloprotease inhibitor TIMP proteins control FGF-2 bioavailability and regulate skeletal growth
Regulated growth plate activity is essential for postnatal bone development and body stature, yet the systems regulating epiphyseal fusion are poorly understood. Here, we show that the tissue inhibitors of metalloprotease (TIMP) gene family is essential for normal bone growth after birth. Whole-body quadruple-knockout mice lacking all four TIMPs have growth plate closure in long bones, precipitating limb shortening, epiphyseal distortion, and widespread chondrodysplasia. We identify TIMP/FGF-2/IHH as a novel nexus underlying bone lengthening where TIMPs negatively regulate the release of FGF-2 from chondrocytes to allow IH...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Saw, S., Aiken, A., Fang, H., McKee, T. D., Bregant, S., Sanchez, O., Chen, Y., Weiss, A., Dickson, B. C., Czarny, B., Sinha, A., Fosang, A., Dive, V., Waterhouse, P. D., Kislinger, T., Khokha, R. Tags: Cell Signaling, Development Articles Source Type: research

Mechanical stress impairs pheromone signaling via Pkc1-mediated regulation of the MAPK scaffold Ste5
Cells continuously adapt cellular processes by integrating external and internal signals. In yeast, multiple stress signals regulate pheromone signaling to prevent mating under unfavorable conditions. However, the underlying crosstalk mechanisms remain poorly understood. Here, we show that mechanical stress activates Pkc1, which prevents lysis of pheromone-treated cells by inhibiting polarized growth. In vitro Pkc1 phosphorylates conserved residues within the RING-H2 domains of the scaffold proteins Far1 and Ste5, which are also phosphorylated in vivo. Interestingly, Pkc1 triggers dispersal of Ste5 from mating projections ...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: van Drogen, F., Mishra, R., Rudolf, F., Walczak, M. J., Lee, S. S., Reiter, W., Hegemann, B., Pelet, S., Dohnal, I., Binolfi, A., Yudina, Z., Selenko, P., Wider, G., Ammerer, G., Peter, M. Tags: Cell Signaling, Biochemistry Articles Source Type: research

{alpha}-Integrins dictate distinct modes of type IV collagen recruitment to basement membranes
Basement membranes (BMs) are cell-associated extracellular matrices that support tissue integrity, signaling, and barrier properties. Type IV collagen is critical for BM function, yet how it is directed into BMs in vivo is unclear. Through live-cell imaging of endogenous localization, conditional knockdown, and misexpression experiments, we uncovered distinct mechanisms of integrin-mediated collagen recruitment to Caenorhabditis elegans postembryonic gonadal and pharyngeal BMs. The putative laminin-binding αINA-1/βPAT-3 integrin was selectively activated in the gonad and recruited laminin, which directed moderat...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Jayadev, R., Chi, Q., Keeley, D. P., Hastie, E. L., Kelley, L. C., Sherwood, D. R. Tags: Adhesion, Membrane and Lipid Biology, Development Articles Source Type: research

Spatiotemporal dynamics of GEF-H1 activation controlled by microtubule- and Src-mediated pathways
Rho family GTPases are activated with precise spatiotemporal control by guanine nucleotide exchange factors (GEFs). Guanine exchange factor H1 (GEF-H1), a RhoA activator, is thought to act as an integrator of microtubule (MT) and actin dynamics in diverse cell functions. Here we identify a GEF-H1 autoinhibitory sequence and exploit it to produce an activation biosensor to quantitatively probe the relationship between GEF-H1 conformational change, RhoA activity, and edge motion in migrating cells with micrometer- and second-scale resolution. Simultaneous imaging of MT dynamics and GEF-H1 activity revealed that autoinhibited...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Azoitei, M. L., Noh, J., Marston, D. J., Roudot, P., Marshall, C. B., Daugird, T. A., Lisanza, S. L., Sandi, M.-J., Ikura, M., Sondek, J., Rottapel, R., Hahn, K. M., Danuser, G. Tags: Cytoskeleton, Migration, Motility, Systems and Computational Biology Articles Source Type: research

SRC and ERK cooperatively phosphorylate DLC1 and attenuate its Rho-GAP and tumor suppressor functions
SRC and ERK kinases control many cell biological processes that promote tumorigenesis by altering the activity of oncogenic and tumor suppressor proteins. We identify here a physiological interaction between DLC1, a focal adhesion protein and tumor suppressor, with SRC and ERK. The tumor suppressor function of DLC1 is attenuated by phosphorylation of tyrosines Y451 and Y701 by SRC, which down-regulates DLC1’s tensin-binding and Rho-GAP activities. ERK1/2 phosphorylate DLC1 on serine S129, which increases both the binding of SRC to DLC1 and SRC-dependent phosphorylation of DLC1. SRC inhibitors exhibit potent antitumor...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Tripathi, B. K., Anderman, M. F., Qian, X., Zhou, M., Wang, D., Papageorge, A. G., Lowy, D. R. Tags: Cell Signaling, Cancer Articles Source Type: research

SNX3 drives maturation of Borrelia phagosomes by forming a hub for PI(3)P, Rab5a, and galectin-9
The spirochete Borrelia burgdorferi, the causative agent of Lyme disease, is internalized by macrophages and processed in phagolysosomes. Phagosomal compaction, a crucial step in phagolysosome maturation, is driven by contact of Rab5a-positive vesicles with the phagosomal coat. We show that the sorting nexin SNX3 is transported with Rab5a vesicles and that its PX domain enables vesicle–phagosome contact by binding to PI(3)P in the phagosomal coat. Moreover, the C-terminal region of SNX3 recruits galectin-9, a lectin implicated in protein and membrane recycling, which we identify as a further regulator of phagosome co...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Klose, M., Salloum, J. E., Gonschior, H., Linder, S. Tags: Trafficking, Immunology Articles Source Type: research

Retromer and TBC1D5 maintain late endosomal RAB7 domains to enable amino acid-induced mTORC1 signaling
Retromer is an evolutionarily conserved multiprotein complex that orchestrates the endocytic recycling of integral membrane proteins. Here, we demonstrate that retromer is also required to maintain lysosomal amino acid signaling through mTORC1 across species. Without retromer, amino acids no longer stimulate mTORC1 translocation to the lysosomal membrane, which leads to a loss of mTORC1 activity and increased induction of autophagy. Mechanistically, we show that its effect on mTORC1 activity is not linked to retromer’s role in the recycling of transmembrane proteins. Instead, retromer cooperates with the RAB7-GAP TBC...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Kvainickas, A., Nägele, H., Qi, W., Dokladal, L., Jimenez-Orgaz, A., Stehl, L., Gangurde, D., Zhao, Q., Hu, Z., Dengjel, J., De Virgilio, C., Baumeister, R., Steinberg, F. Tags: Trafficking Articles Source Type: research

BIK ubiquitination by the E3 ligase Cul5-ASB11 determines cell fate during cellular stress
The BH3-only pro-apoptotic protein BIK is regulated by the ubiquitin–proteasome system. However, the mechanism of this regulation and its physiological functions remain elusive. Here, we identify Cul5-ASB11 as the E3 ligase targeting BIK for ubiquitination and degradation. ER stress leads to the activation of ASB11 by XBP1s during the adaptive phase of the unfolded protein response, which stimulates BIK ubiquitination, interaction with p97/VCP, and proteolysis. This mechanism of BIK degradation contributes to ER stress adaptation by promoting cell survival. Conversely, genotoxic agents down-regulate this IRE1α&...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Chen, F.-Y., Huang, M.-Y., Lin, Y.-M., Ho, C.-H., Lin, S.-Y., Chen, H.-Y., Hung, M.-C., Chen, R.-H. Tags: Cell Death and Autophagy, Cell Signaling, Biochemistry, Cancer Articles Source Type: research

Hook3 is a scaffold for the opposite-polarity microtubule-based motors cytoplasmic dynein-1 and KIF1C
The unidirectional and opposite-polarity microtubule-based motors, dynein and kinesin, drive long-distance intracellular cargo transport. Cellular observations suggest that opposite-polarity motors may be coupled. We recently identified an interaction between the cytoplasmic dynein-1 activating adaptor Hook3 and the kinesin-3 KIF1C. Here, using in vitro reconstitutions with purified components, we show that KIF1C and dynein/dynactin can exist in a complex scaffolded by Hook3. Full-length Hook3 binds to and activates dynein/dynactin motility. Hook3 also binds to a short region in the "tail" of KIF1C, but unlike dy...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Kendrick, A. A., Dickey, A. M., Redwine, W. B., Tran, P. T., Vaites, L. P., Dzieciatkowska, M., Harper, J. W., Reck-Peterson, S. L. Tags: Cytoskeleton, Biochemistry, Biophysics Articles Source Type: research

Imaging within single NPCs reveals NXF1s role in mRNA export on the cytoplasmic side of the pore
Translocation of mRNA through the nuclear pore complex (NPC) requires interactions with different NPC regions. To determine the interactions that are crucial for effective mRNA export in living cells, we examined mRNA export within individual pores by applying various types of mRNA export blocks that stalled mRNPs at different stages of transition. Focusing on the major mRNA export factor NXF1, we found that initial mRNP binding to the NPC did not require NXF1 in the NPC, whereas release into the cytoplasm did. NXF1 localization in the NPC did not require RNA or RNA binding. Superresolution microscopy showed that NXF1 cons...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Ben-Yishay, R., Mor, A., Shraga, A., Ashkenazy-Titelman, A., Kinor, N., Schwed-Gross, A., Jacob, A., Kozer, N., Kumar, P., Garini, Y., Shav-Tal, Y. Tags: RNA Biology Articles Source Type: research

Chromatin targeting of nuclear pore proteins induces chromatin decondensation
Nuclear pore complexes have emerged in recent years as chromatin-binding nuclear scaffolds, able to influence target gene expression. However, how nucleoporins (Nups) exert this control remains poorly understood. Here we show that ectopically tethering Drosophila Nups, especially Sec13, to chromatin is sufficient to induce chromatin decondensation. This decondensation is mediated through chromatin-remodeling complex PBAP, as PBAP is both robustly recruited by Sec13 and required for Sec13-induced decondensation. This phenomenon is not correlated with localization of the target locus to the nuclear periphery, but is correlat...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Kuhn, T. M., Pascual-Garcia, P., Gozalo, A., Little, S. C., Capelson, M. Tags: Chromatin or Epigenetics, Development, Genetics Articles Source Type: research

Chromatin compartment dynamics in a haploinsufficient model of cardiac laminopathy
Mutations in A-type nuclear lamins cause dilated cardiomyopathy, which is postulated to result from dysregulated gene expression due to changes in chromatin organization into active and inactive compartments. To test this, we performed genome-wide chromosome conformation analyses in human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) with a haploinsufficient mutation for lamin A/C. Compared with gene-corrected cells, mutant hiPSC-CMs have marked electrophysiological and contractile alterations, with modest gene expression changes. While large-scale changes in chromosomal topology are evident, diffe...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Bertero, A., Fields, P. A., Smith, A. S. T., Leonard, A., Beussman, K., Sniadecki, N. J., Kim, D.-H., Tse, H.-F., Pabon, L., Shendure, J., Noble, W. S., Murry, C. E. Tags: Disease, Chromatin or Epigenetics, DNA Biology, Genetics Articles Source Type: research

CDK2 regulates the NRF1/Ehmt1 axis during meiotic prophase I
Meiosis generates four genetically distinct haploid gametes over the course of two reductional cell divisions. Meiotic divisions are characterized by the coordinated deposition and removal of various epigenetic marks. Here we propose that nuclear respiratory factor 1 (NRF1) regulates transcription of euchromatic histone methyltransferase 1 (EHMT1) to ensure normal patterns of H3K9 methylation during meiotic prophase I. We demonstrate that cyclin-dependent kinase (CDK2) can bind to the promoters of a number of genes in male germ cells including that of Ehmt1 through interaction with the NRF1 transcription factor. Our data i...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Palmer, N., Talib, S. Z. A., Ratnacaram, C. K., Low, D., Bisteau, X., Lee, J. H. S., Pfeiffenberger, E., Wollmann, H., Tan, J. H. L., Wee, S., Sobota, R., Gunaratne, J., Messerschmidt, D. M., Guccione, E., Kaldis, P. Tags: Cell Cycle and Division, Genetics Articles Source Type: research

Coordinated internodal and paranodal adhesion controls accurate myelination by oligodendrocytes
Oligodendrocyte–axon contact is mediated by several cell adhesion molecules (CAMs) that are positioned at distinct sites along the myelin unit, yet their role during myelination remains unclear. Cadm4 and its axonal receptors, Cadm2 and Cadm3, as well as myelin-associated glycoprotein (MAG), are enriched at the internodes below the compact myelin, whereas NF155, which binds the axonal Caspr/contactin complex, is located at the paranodal junction that is formed between the axon and the terminal loops of the myelin sheath. Here we report that Cadm4-, MAG-, and Caspr-mediated adhesion cooperate during myelin membrane en...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Elazar, N., Vainshtein, A., Rechav, K., Tsoory, M., Eshed-Eisenbach, Y., Peles, E. Tags: Adhesion, Neuroscience Reports Source Type: research

A bipartite sorting signal ensures specificity of retromer complex in membrane protein recycling
Retromer is an evolutionarily conserved protein complex, which sorts functionally diverse membrane proteins into recycling tubules/vesicles from the endosome. Many of the identified cargos possess a recycling signal sequence defined as ØX[L/M/V], where Ø is F/Y/W. However, this sequence is present in almost all proteins encoded in the genome. Also, several identified recycling sequences do not follow this rule. How then does retromer precisely select its cargos? Here, we reveal that an additional motif is also required for cargo retrieval. The two distinct motifs form a bipartite recycling signal recognized b...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Suzuki, S. W., Chuang, Y.-S., Li, M., Seaman, M. N. J., Emr, S. D. Tags: Trafficking, Biochemistry Reports Source Type: research

Basal CHK1 activity safeguards its stability to maintain intrinsic S-phase checkpoint functions
The DNA replication machinery frequently encounters impediments that slow replication fork progression and threaten timely and error-free replication. The CHK1 protein kinase is essential to deal with replication stress (RS) and ensure genome integrity and cell survival, yet how basal levels and activity of CHK1 are maintained under physiological, unstressed conditions is not well understood. Here, we reveal that CHK1 stability is controlled by its steady-state activity during unchallenged cell proliferation. This autoactivatory mechanism, which depends on ATR and its coactivator ETAA1 and is tightly associated with CHK1 a...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Michelena, J., Gatti, M., Teloni, F., Imhof, R., Altmeyer, M. Tags: Cell Cycle and Division, DNA Biology, Cancer Reports Source Type: research

The molecular architecture of the meiotic spindle is remodeled during metaphase arrest in oocytes
Before fertilization, oocytes of most species undergo a long, natural arrest in metaphase. Before this, prometaphase I is also prolonged, due to late stable kinetochore–microtubule attachment. How oocytes stably maintain the dynamic spindle for hours during these periods is poorly understood. Here we report that the bipolar spindle changes its molecular architecture during the long prometaphase/metaphase I in Drosophila melanogaster oocytes. By generating transgenic flies expressing GFP-tagged spindle proteins, we found that 14 of 25 spindle proteins change their distribution in the bipolar spindle. Among them, micro...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Costa, M. F. A., Ohkura, H. Tags: Cytoskeleton, Cell Cycle and Division, Development, Genetics Reports Source Type: research

Microtubule minus-end stability is dictated by the tubulin off-rate
Dynamic organization of microtubule minus ends is vital for the formation and maintenance of acentrosomal microtubule arrays. In vitro, both microtubule ends switch between phases of assembly and disassembly, a behavior called dynamic instability. Although minus ends grow slower, their lifetimes are similar to those of plus ends. The mechanisms underlying these distinct dynamics remain unknown. Here, we use an in vitro reconstitution approach to investigate minus-end dynamics. We find that minus-end lifetimes are not defined by the mean size of the protective GTP-tubulin cap. Rather, we conclude that the distinct tubulin o...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Strothman, C., Farmer, V., Arpag, G., Rodgers, N., Podolski, M., Norris, S., Ohi, R., Zanic, M. Tags: Cytoskeleton, Biochemistry, Biophysics Reports Source Type: research

Direct observation of branching MT nucleation in living animal cells
Centrosome-mediated microtubule (MT) nucleation has been well characterized; however, numerous noncentrosomal MT nucleation mechanisms exist. The branching MT nucleation pathway envisages that the -tubulin ring complex (-TuRC) is recruited to MTs by the augmin complex to initiate nucleation of new MTs. While the pathway is well conserved at a molecular and functional level, branching MT nucleation by core constituents has never been directly observed in animal cells. Here, multicolor TIRF microscopy was applied to visualize and quantitatively define the entire process of branching MT nucleation in dividing Drosophila cells...
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Verma, V., Maresca, T. J. Tags: Cytoskeleton, Cell Cycle and Division Reports Source Type: research

Early Career Advisory Board
In 2019, JCB created an Early Career Advisory Board as part of our ongoing efforts to ensure that the journal is representative and responsive to the needs of the entire cell biology community. Our Early Career Advisory Board members... (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Tags: Editorial Source Type: research

Challenging the "chromatin hypothesis" of cardiac laminopathies with LMNA mutant iPS cells
Lamins A and C are intermediate filaments that provide structural support to the nuclear envelope and regulate gene expression. In this issue, Bertero et al. (2019. J. Cell Biol. report that although lamin A/C haploinsufficient cardiomyocytes show disease-associated phenotypes, those changes cannot be explained by alterations in chromatin compartmentalization. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Mozzetta, C., Tedesco, F. S. Tags: Spotlight Source Type: research

Healthy attachments: Cell adhesion molecules collectively control myelin integrity
Many cell adhesion molecules are present along myelinated axons and in myelinating glia, but functional interactions among these proteins have not been fully elucidated. In this issue, Elazar et al. (2019. J. Cell Biol. report that distinct adhesion proteins act in coordination to ensure accurate myelination. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Li, J., Monk, K. R. Tags: Spotlight Source Type: research

GTP-tubulin loves microtubule plus ends but marries the minus ends
Microtubule minus ends are inherently more stable than plus ends despite the fact that free tubulin associates more avidly to the plus end. In this issue, Strothman et al. (2019. J. Cell Biol. measure, for the first time, the off-rate for GTP-tubulin and find that it is different for the two ends, suggesting that this parameter may control the transition to disassembly at microtubule ends. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - September 2, 2019 Category: Cytology Authors: Wordeman, L. Tags: Cytoskeleton, Cell Cycle and Division, Biochemistry, Cancer Spotlight Source Type: research