1
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Chen W, He B. Actomyosin activity-dependent apical targeting of Rab11 vesicles reinforces apical constriction. J Cell Biol 2022; 221:213118. [DOI: 10.1083/jcb.202103069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 01/23/2022] [Accepted: 03/08/2022] [Indexed: 11/22/2022] Open
Abstract
During tissue morphogenesis, the changes in cell shape, resulting from cell-generated forces, often require active regulation of intracellular trafficking. How mechanical stimuli influence intracellular trafficking and how such regulation impacts tissue mechanics are not fully understood. In this study, we identify an actomyosin-dependent mechanism involving Rab11-mediated trafficking in regulating apical constriction in the Drosophila embryo. During Drosophila mesoderm invagination, apical actin and Myosin II (actomyosin) contractility induces apical accumulation of Rab11-marked vesicle-like structures (“Rab11 vesicles”) by promoting a directional bias in dynein-mediated vesicle transport. At the apical domain, Rab11 vesicles are enriched near the adherens junctions (AJs). The apical accumulation of Rab11 vesicles is essential to prevent fragmented apical AJs, breaks in the supracellular actomyosin network, and a reduction in the apical constriction rate. This Rab11 function is separate from its role in promoting apical Myosin II accumulation. These findings suggest a feedback mechanism between actomyosin activity and Rab11-mediated intracellular trafficking that regulates the force generation machinery during tissue folding.
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Affiliation(s)
- Wei Chen
- Department of Biological Sciences, Dartmouth College, Hanover, NH
| | - Bing He
- Department of Biological Sciences, Dartmouth College, Hanover, NH
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2
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Djokic S, Bakhrat A, Li M, Akbari OS, Abdu U. Scale-type-specific requirement for the mosquito Aedes aegypti Spindle-F homologue by regulating microtubule organization. INSECT MOLECULAR BIOLOGY 2022; 31:216-224. [PMID: 34919304 PMCID: PMC10537241 DOI: 10.1111/imb.12752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/11/2021] [Accepted: 12/12/2021] [Indexed: 06/14/2023]
Abstract
Insect epithelial cells contain unique cellular extensions such as bristles, hairs, and scales. In contrast to bristle and hair, which are not divergent in their shape, scale morphology shows high diversity. In our attempt to characterize the role of the insect-specific gene, Spindle-F (spn-F), in mosquito development, we revealed a scale-type specific requirement for the mosquito Aedes aegypti spn-F homologue. Using CRISPR-Cas9, we generated Ae-spn-F mutants and found that Ae-spn-F is an essential gene, but we were able to recover a few adult escapers. These escapers could not fly nor move, and died after 3 to 4 days. We found that in Ae-spn-F mutants, only the tip part of the bristle was affected with bulbous with misoriented ribs. We also show that in Ae-spn-F mutants, only in falcate scales, which are curved with a sharp or narrowly rounded apex, and not in other scale types, the tip region is strongly affected. Our analysis also revealed that in contrast to Drosophila spn-F, which show strong defects in both the actin and microtubule (MT) network in the bristle, the Ae-spn-F gene is required only for MT organization in scales and bristles. In summary, our results reveal that Ae-spn-F is required for shaping tapered epithelial cellular extension structures, namely, the bristle and falcate scales by affecting MT organization.
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Affiliation(s)
- Sanja Djokic
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Anna Bakhrat
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ming Li
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, San Diego, CA, USA
| | - Omar S. Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, San Diego, CA, USA
| | - Uri Abdu
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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3
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Barros CS, Bossing T. Microtubule disruption upon CNS damage triggers mitotic entry via TNF signaling activation. Cell Rep 2021; 36:109325. [PMID: 34233183 DOI: 10.1016/j.celrep.2021.109325] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/12/2020] [Accepted: 06/08/2021] [Indexed: 01/15/2023] Open
Abstract
Repair after traumatic injury often starts with mitotic activation around the lesion edges. Early midline cells in the Drosophila embryonic CNS can enter into division following the traumatic disruption of microtubules. We demonstrate that microtubule disruption activates non-canonical TNF signaling by phosphorylation of TGF-β activated kinase 1 (Tak1) and its target IkappaB kinase (Ik2), culminating in Dorsal/NfkappaB nuclear translocation and Jra/Jun expression. Tak1 and Ik2 are necessary for the damaged-induced divisions. Microtubule disruption caused by Tau accumulation is also reported in Alzheimer's disease (AD). Human Tau expression in Drosophila midline cells is sufficient to induce Tak1 phosphorylation, Dorsal and Jra/Jun expression, and entry into mitosis. Interestingly, activation of Tak1 and Tank binding kinase 1 (Tbk1), the human Ik2 ortholog, and NfkappaB upregulation are observed in AD brains.
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Affiliation(s)
- Claudia S Barros
- Peninsula Medical School, Faculty of Health, University of Plymouth, John Bull Building, 16 Research Way, Plymouth PL6 8BU, UK
| | - Torsten Bossing
- Peninsula Medical School, Faculty of Health, University of Plymouth, John Bull Building, 16 Research Way, Plymouth PL6 8BU, UK.
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4
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Bergalet J, Patel D, Legendre F, Lapointe C, Benoit Bouvrette LP, Chin A, Blanchette M, Kwon E, Lécuyer E. Inter-dependent Centrosomal Co-localization of the cen and ik2 cis-Natural Antisense mRNAs in Drosophila. Cell Rep 2021; 30:3339-3352.e6. [PMID: 32160541 DOI: 10.1016/j.celrep.2020.02.047] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 12/24/2019] [Accepted: 02/10/2020] [Indexed: 11/30/2022] Open
Abstract
Overlapping genes are prevalent in most genomes, but the extent to which this organization influences regulatory events operating at the post-transcriptional level remains unclear. Studying the cen and ik2 genes of Drosophila melanogaster, which are convergently transcribed as cis-natural antisense transcripts (cis-NATs) with overlapping 3' UTRs, we found that their encoded mRNAs strikingly co-localize to centrosomes. These transcripts physically interact in a 3' UTR-dependent manner, and the targeting of ik2 requires its 3' UTR sequence and the presence of cen mRNA, which serves as the main driver of centrosomal co-localization. The cen transcript undergoes localized translation in proximity to centrosomes, and its localization is perturbed by polysome-disrupting drugs. By interrogating global fractionation-sequencing datasets generated from Drosophila and human cellular models, we find that RNAs expressed as cis-NATs tend to co-localize to specific subcellular fractions. This work suggests that post-transcriptional interactions between RNAs with complementary sequences can dictate their localization fate in the cytoplasm.
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Affiliation(s)
- Julie Bergalet
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Dhara Patel
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Félix Legendre
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Catherine Lapointe
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Louis Philip Benoit Bouvrette
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Ashley Chin
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | | | - Eunjeong Kwon
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Eric Lécuyer
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de Biochimie et Médecine Moléculaire and Programme de Biologie Moléculaire, Université de Montréal, Montréal, QC, Canada; Division of Experimental Medicine, McGill University, Montréal, QC, Canada.
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5
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Rab11 activation by Ik2 kinase is required for dendrite pruning in Drosophila sensory neurons. PLoS Genet 2020; 16:e1008626. [PMID: 32059017 PMCID: PMC7046344 DOI: 10.1371/journal.pgen.1008626] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 02/27/2020] [Accepted: 01/23/2020] [Indexed: 12/31/2022] Open
Abstract
Neuronal pruning is a commonly observed phenomenon for the developing nervous systems to ensure precise wiring of neural circuits. The function of Ik2 kinase and its downstream mediator, Spindle-F (Spn-F), are essential for dendrite pruning of Drosophila sensory neurons during development. However, little is known about how Ik2/Spn-F signaling is transduced in neurons and ultimately results in dendrite pruning. Our genetic analyses and rescue experiments demonstrated that the small GTPase Rab11, especially the active GTP-bound form, is required for dendrite pruning. We also found that Rab11 shows genetic interactions with spn-F and ik2 on pruning. Live imaging of single neurons and antibody staining reveal normal Ik2 kinase activation in Rab11 mutant neurons, suggesting that Rab11 could have a functional connection downstream of and/or parallel to the Ik2 kinase signaling. Moreover, we provide biochemical evidence that both the Ik2 kinase activity and the formation of Ik2/Spn-F/Rab11 complexes are central to promote Rab11 activation in cells. Together, our studies reveal that a critical role of Ik2/Spn-F signaling in neuronal pruning is to promote Rab11 activation, which is crucial for dendrite pruning in neurons. During metamorphosis in Drosophila, both the central and peripheral nervous systems undergo substantial neuronal remodeling, such as the cell death of most larval neurons and regeneration of adult neurons, while few larval neurons remain alive and prune their branches. Pruning is a self-destruction program, and thus requires to be tightly controlled within single neurons spatially and temporally during development. Recent studies have shown a strong correlation between pruning and human psychiatric disorders, such as schizophrenia and autism. Drosophila sensory neurons that undergo dendrite pruning provide us an opportunity to study the regulatory mechanism of neuronal pruning. Previously, we identified an IKK-related kinase Ik2 that is essential and sufficient for dendrite pruning, and a coiled-coil protein Spindle-F that mediates Ik2-dependent pruning activity in neurons. However, what are the downstream targets of Ik2/Spindle-F signaling in dendrite pruning remains unclear. In this study, we found that the small GTPase Rab11, especially the active GTP-bound form, is required for dendrite pruning in neurons. We further demonstrated that both the Ik2 kinase activity and Ik2/Spindle-F complexes are essential to enhance Rab11 activation in neurons during dendrite pruning.
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6
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The organization of Golgi in Drosophila bristles requires microtubule motor protein function and a properly organized microtubule array. PLoS One 2019; 14:e0223174. [PMID: 31577833 PMCID: PMC6774520 DOI: 10.1371/journal.pone.0223174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 09/16/2019] [Indexed: 11/20/2022] Open
Abstract
In the present report, we used highly elongated Drosophila bristle cells to dissect the role of dynein heavy chain (Dhc64C) in Golgi organization. We demonstrated that whereas in the bristle "somal" region Golgi units are composed of cis-, medial, and trans-Golgi compartments ("complete Golgi"), the bristle shaft contains Golgi satellites that lack the trans-Golgi compartment (hereafter referred to as "incomplete Golgi") and which are static and localized at the base area. However, in Dhc64C mutants, the entire bristle shaft was filled with complete Golgi units containing ectopic trans-Golgi components. To further understand Golgi bristle organization, we tested the roles of microtubule (MT) polarity and the Dhc-opposing motor, kinesin heavy chain (Khc). For our surprise, we found that in Khc and Ik2Dominant-negative (DN) flies in which the polarized organization of MTs is affected, the bristle shaft was filled with complete Golgi, similarly to what is seen in Dhc64C flies. Thus, we demonstrated that MTs and the motor proteins Dhc and Khc are required for bristle Golgi organization. However, the fact that both Dhc64C and Khc flies showed similar Golgi defects calls for an additional work to elucidate the molecular mechanism describing why these factors are required for bristle Golgi organization.
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7
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Krämer R, Rode S, Rumpf S. Rab11 is required for neurite pruning and developmental membrane protein degradation in Drosophila sensory neurons. Dev Biol 2019; 451:68-78. [DOI: 10.1016/j.ydbio.2019.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 03/05/2019] [Accepted: 03/05/2019] [Indexed: 12/11/2022]
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8
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Baskar R, Bahkrat A, Otani T, Wada H, Davidov G, Pandey H, Gheber L, Zarivach R, Hayashi S, Abdu U. The plus-tip tracking and microtubule stabilizing activities of Javelin-like regulate microtubule organization and cell polarity. FEBS J 2019; 286:3811-3830. [PMID: 31152621 DOI: 10.1111/febs.14944] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 05/03/2019] [Accepted: 05/30/2019] [Indexed: 11/29/2022]
Abstract
Cell polarity is essential for building cell asymmetry in all eukaryotic cells. Drosophila oocyte and bristle development require the newly characterized Spn-F protein complex, which includes Spn-F, IKKε, and Javelin-like (Jvl), to establish polarity. Jvl is a novel microtubule (MT)-associated protein; however, the mechanism by which it regulates MT organization is still unknown. We found that overexpression of Jvl stabilizes MTs and that jvl is needed for stable MT arrangement at the bristle tip and organization of the dynamic MT throughout the bristle shaft. At low levels of expression in cultured cells, Jvl behaved as a microtubule plus-end tracking protein. We demonstrated that Jvl physically interacts with the highly conserved MT end-binding protein 1 (EB1) using yeast two-hybrid and GST pull-down assays. This interaction is, however, dispensable for Jvl function in oocyte and bristle development. In addition, using a MT-binding assay, we saw that Jvl-C terminus directly binds to MTs. We also revealed that oocyte developmental arrest caused by Jvl overexpression in the germline can be rescued by mutations in its partners, spn-F and ikkε, suggesting that complex formation with Spn-F and IKKε is required for Jvl function in vivo. In summary, our results show that the microtubule plus-end tracking and stabilizing activities of Jvl are central for controlling cell polarity of oocytes and bristles.
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Affiliation(s)
- Raju Baskar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Anna Bahkrat
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Tetsuhisa Otani
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics, Kobe, Japan
| | - Housei Wada
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics, Kobe, Japan
| | - Geula Davidov
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,National Institute for Biotechnology in the Negev and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Himanshu Pandey
- Department of Chemistry and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Larisa Gheber
- Department of Chemistry and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,National Institute for Biotechnology in the Negev and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Shigeo Hayashi
- Laboratory for Morphogenetic Signaling, RIKEN Center for Biosystems Dynamics, Kobe, Japan
| | - Uri Abdu
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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9
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The Small GTPase Arf6: An Overview of Its Mechanisms of Action and of Its Role in Host⁻Pathogen Interactions and Innate Immunity. Int J Mol Sci 2019; 20:ijms20092209. [PMID: 31060328 PMCID: PMC6539230 DOI: 10.3390/ijms20092209] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/26/2019] [Accepted: 04/27/2019] [Indexed: 12/15/2022] Open
Abstract
The small GTase Arf6 has several important functions in intracellular vesicular trafficking and regulates the recycling of different types of cargo internalized via clathrin-dependent or -independent endocytosis. It activates the lipid modifying enzymes PIP 5-kinase and phospholipase D, promotes actin polymerization, and affects several functionally distinct processes in the cell. Arf6 is used for the phagocytosis of pathogens and can be directly or indirectly targeted by various pathogens to block phagocytosis or induce the uptake of intracellular pathogens. Arf6 is also used in the signaling of Toll-like receptors and in the activation of NADPH oxidases. In this review, we first give an overview of the different roles and mechanisms of action of Arf6 and then focus on its role in innate immunity and host–pathogen interactions.
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Ando T, Sekine S, Inagaki S, Misaki K, Badel L, Moriya H, Sami MM, Itakura Y, Chihara T, Kazama H, Yonemura S, Hayashi S. Nanopore Formation in the Cuticle of an Insect Olfactory Sensillum. Curr Biol 2019; 29:1512-1520.e6. [PMID: 31006566 DOI: 10.1016/j.cub.2019.03.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/18/2019] [Accepted: 03/20/2019] [Indexed: 10/27/2022]
Abstract
Nanometer-level patterned surface structures form the basis of biological functions, including superhydrophobicity, structural coloration, and light absorption [1-3]. In insects, the cuticle overlying the olfactory sensilla has multiple small (50- to 200-nm diameter) pores [4-8], which are supposed to function as a filter that admits odorant molecules, while preventing the entry of larger airborne particles and limiting water loss. However, the cellular processes underlying the patterning of extracellular matrices into functional nano-structures remain unknown. Here, we show that cuticular nanopores in Drosophila olfactory sensilla originate from a curved ultrathin film that is formed in the outermost envelope layer of the cuticle and secreted from specialized protrusions in the plasma membrane of the hair forming (trichogen) cell. The envelope curvature coincides with plasma membrane undulations associated with endocytic structures. The gore-tex/Osiris23 gene encodes an endosomal protein that is essential for envelope curvature, nanopore formation, and odor receptivity and is expressed specifically in developing olfactory trichogen cells. The 24-member Osiris gene family is expressed in cuticle-secreting cells and is found only in insect genomes. These results reveal an essential requirement for nanopores for odor reception and identify Osiris genes as a platform for investigating the evolution of surface nano-fabrication in insects.
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Affiliation(s)
- Toshiya Ando
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Sayaka Sekine
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Sachi Inagaki
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Kazuyo Misaki
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Laurent Badel
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hiroyuki Moriya
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Mustafa M Sami
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Yuki Itakura
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Takahiro Chihara
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Hokto Kazama
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Shigenobu Yonemura
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Shigeo Hayashi
- RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Department of Biology, Kobe University Graduate School of Science, Kobe, Hyogo 657-8501, Japan.
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Jouette J, Guichet A, Claret SB. Dynein-mediated transport and membrane trafficking control PAR3 polarised distribution. eLife 2019; 8:40212. [PMID: 30672465 PMCID: PMC6358217 DOI: 10.7554/elife.40212] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/03/2019] [Indexed: 12/14/2022] Open
Abstract
The scaffold protein PAR3 and the kinase PAR1 are essential proteins that control cell polarity. Their precise opposite localisations define plasma membrane domains with specific functions. PAR3 and PAR1 are mutually inhibited by direct or indirect phosphorylations, but their fates once phosphorylated are poorly known. Through precise spatiotemporal quantification of PAR3 localisation in the Drosophila oocyte, we identify several mechanisms responsible for its anterior cortex accumulation and its posterior exclusion. We show that PAR3 posterior plasma membrane exclusion depends on PAR1 and an endocytic mechanism relying on RAB5 and PI(4,5)P2. In a second phase, microtubules and the dynein motor, in connection with vesicular trafficking involving RAB11 and IKK-related kinase, IKKε, are required for PAR3 transport towards the anterior cortex. Altogether, our results point to a connection between membrane trafficking and dynein-mediated transport to sustain PAR3 asymmetry.
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Affiliation(s)
- Julie Jouette
- Institut Jacques Monod, CNRS, UMR 7592, Paris Diderot University, Sorbonne Paris Cité, Paris, France
| | - Antoine Guichet
- Institut Jacques Monod, CNRS, UMR 7592, Paris Diderot University, Sorbonne Paris Cité, Paris, France
| | - Sandra B Claret
- Institut Jacques Monod, CNRS, UMR 7592, Paris Diderot University, Sorbonne Paris Cité, Paris, France
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12
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Yang Z, Honda T, Ueda K. vFLIP upregulates IKKε, leading to spindle morphology formation through RelA activation. Virology 2018; 522:106-121. [PMID: 30029010 DOI: 10.1016/j.virol.2018.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/07/2018] [Accepted: 07/07/2018] [Indexed: 12/31/2022]
Abstract
Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) vFLIP, a latent gene of KSHV, was first identified as a FLICE-inhibitory protein (FLIP) protecting cells from apoptosis. The vFLIP protein has been shown to activate the NF-κB signaling involved in spindle morphology formation both in HUVECs infected with KSHV and Kaposi's sarcoma (KS) itself. In this study, we independently established stably vFLIP-expressing cells and showed that they exhibited upregulated NF-κB family protein expression independent of the ability of IKKs to bind vFLIP. Further, vFLIP induced upregulation of IKKε, phosphorylation of RelA at Ser468 (p-RelA S468) and nuclear localization of Re1A concomitant with spindle morphology formation, and these effects were reversed by knockdown of IKKε and treatment with Bay-11. Overexpression of IKKε alone also showed spindle morphology formation with p-RelA S468. In conclusion, the spindle cell morphology in KS should be induced by RelA activation (p-RelA S468) by IKKε upregulation in vFLIP-expressing EA hy926 cells.
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Affiliation(s)
- Zunlin Yang
- Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Tomoyuki Honda
- Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Keiji Ueda
- Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
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13
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Brose L, Crest J, Tao L, Sullivan W. Polo kinase mediates the phosphorylation and cellular localization of Nuf/FIP3, a Rab11 effector. Mol Biol Cell 2017; 28:1435-1443. [PMID: 28381422 PMCID: PMC5449144 DOI: 10.1091/mbc.e16-04-0236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 03/23/2017] [Accepted: 03/31/2017] [Indexed: 01/28/2023] Open
Abstract
Animal cytokinesis involves both actin-myosin-based contraction and vesicle-mediated membrane addition. In many cell types, including early Drosophila embryos, Nuf/FIP3, a Rab11 effector, mediates recycling endosome (RE)-based vesicle delivery to the cytokinesis furrow. Nuf exhibits a cell cycle-regulated concentration at the centrosome that is accompanied by dramatic changes in its phosphorylation state. Here we demonstrate that maximal phosphorylation of Nuf occurs at prophase, when centrosome-associated Nuf disperses throughout the cytoplasm. Accordingly, ectopic Cdk1 activation results in immediate Nuf dispersal from the centrosome. Screening of candidate kinases reveals a specific, dosage-sensitive interaction between Nuf and Polo with respect to Nuf-mediated furrow formation. Inhibiting Polo activity results in Nuf underphosphorylation and prolonged centrosome association. In vitro, Polo directly binds and is required for Nuf phosphorylation at Ser-225 and Thr-227, matching previous in vivo-mapped phosphorylation sites. These results demonstrate a role for Polo kinase in directly mediating Nuf cell cycle-dependent localization.
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Affiliation(s)
- Lotti Brose
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Justin Crest
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Li Tao
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
- Department of Biology, University of Hawaii, Hilo, HI 96720
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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Uhm M, Bazuine M, Zhao P, Chiang SH, Xiong T, Karunanithi S, Chang L, Saltiel AR. Phosphorylation of the exocyst protein Exo84 by TBK1 promotes insulin-stimulated GLUT4 trafficking. Sci Signal 2017; 10:10/471/eaah5085. [PMID: 28325821 DOI: 10.1126/scisignal.aah5085] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Insulin stimulates glucose uptake through the translocation of the glucose transporter GLUT4 to the plasma membrane. The exocyst complex tethers GLUT4-containing vesicles to the plasma membrane, a process that requires the binding of the G protein (heterotrimeric guanine nucleotide-binding protein) RalA to the exocyst complex. We report that upon activation of RalA, the protein kinase TBK1 phosphorylated the exocyst subunit Exo84. Knockdown of TBK1 blocked insulin-stimulated glucose uptake and GLUT4 translocation; knockout of TBK1 in adipocytes blocked insulin-stimulated glucose uptake; and ectopic overexpression of a kinase-inactive mutant of TBK1 reduced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. The phosphorylation of Exo84 by TBK1 reduced its affinity for RalA and enabled its release from the exocyst. Overexpression of a kinase-inactive mutant of TBK1 blocked the dissociation of the TBK1/RalA/exocyst complex, and treatment of 3T3-L1 adipocytes with specific inhibitors of TBK1 reduced the rate of complex dissociation. Introduction of phosphorylation-mimicking or nonphosphorylatable mutant forms of Exo84 blocked insulin-stimulated GLUT4 translocation. Thus, these data indicate that TBK1 controls GLUT4 vesicle engagement and disengagement from the exocyst, suggesting that exocyst components not only constitute a tethering complex for the GLUT4 vesicle but also act as "gatekeepers" controlling vesicle fusion at the plasma membrane.
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Affiliation(s)
- Maeran Uhm
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Merlijn Bazuine
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peng Zhao
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,Institute for Diabetes and Metabolic Health, Departments of Medicine and Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Shian-Huey Chiang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Tingting Xiong
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Louise Chang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alan R Saltiel
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA. .,Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.,Institute for Diabetes and Metabolic Health, Departments of Medicine and Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
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15
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Otani T, Ogura Y, Misaki K, Maeda T, Kimpara A, Yonemura S, Hayashi S. IKKε inhibits PKC to promote Fascin-dependent actin bundling. Development 2016; 143:3806-3816. [PMID: 27578797 PMCID: PMC5087637 DOI: 10.1242/dev.138495] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 08/23/2016] [Indexed: 11/20/2022]
Abstract
Signaling molecules have pleiotropic functions and are activated by various extracellular stimuli. Protein kinase C (PKC) is activated by diverse receptors, and its dysregulation is associated with diseases including cancer. However, how the undesired activation of PKC is prevented during development remains poorly understood. We have previously shown that a protein kinase, IKKε, is active at the growing bristle tip and regulates actin bundle organization during Drosophila bristle morphogenesis. Here, we demonstrate that IKKε regulates the actin bundle localization of a dynamic actin cross-linker, Fascin. IKKε inhibits PKC, thereby protecting Fascin from inhibitory phosphorylation. Excess PKC activation is responsible for the actin bundle defects in IKKε-deficient bristles, whereas PKC is dispensable for bristle morphogenesis in wild-type bristles, indicating that PKC is repressed by IKKε in wild-type bristle cells. These results suggest that IKKε prevents excess activation of PKC during bristle morphogenesis. Summary: The protein kinase IKKϵ is active at the growing tip of Drosophila bristles and prevents excess PKC activation during bristle actin bundle organization and morphogenesis.
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Affiliation(s)
- Tetsuhisa Otani
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Yosuke Ogura
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Kazuyo Misaki
- Electron Microscope Laboratory, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Takuya Maeda
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Akiyo Kimpara
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Shigenobu Yonemura
- Electron Microscope Laboratory, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Shigeo Hayashi
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan .,Department of Biology, Kobe University Graduate School of Science, Kobe, Hyogo 657-8501, Japan
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16
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Calero-Cuenca FJ, Espinosa-Vázquez JM, Reina-Campos M, Díaz-Meco MT, Moscat J, Sotillos S. Nuclear fallout provides a new link between aPKC and polarized cell trafficking. BMC Biol 2016; 14:32. [PMID: 27089924 PMCID: PMC4836198 DOI: 10.1186/s12915-016-0253-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 03/31/2016] [Indexed: 12/31/2022] Open
Abstract
Background Cell polarity, essential for cell physiology and tissue coherence, emerges as a consequence of asymmetric localization of protein complexes and directional trafficking of cellular components. Although molecules required in both processes are well known their relationship is still poorly understood. Results Here we show a molecular link between Nuclear Fallout (Nuf), an adaptor of Rab11-GTPase to the microtubule motor proteins during Recycling Endosome (RE) trafficking, and aPKC, a pivotal kinase in the regulation of cell polarity. We demonstrate that aPKC phosphorylates Nuf modifying its subcellular distribution. Accordingly, in aPKC mutants Nuf and Rab11 accumulate apically indicating altered RE delivery. We show that aPKC localization in the apico-lateral cortex is dynamic. When we block exocytosis, by means of exocyst-sec mutants, aPKC accumulates inside the cells. Moreover, apical aPKC concentration is reduced in nuf mutants, suggesting aPKC levels are maintained by recycling. Conclusions We demonstrate that active aPKC interacts with Nuf, phosphorylating it and, as a result, modifying its subcellular distribution. We propose a regulatory loop by which Nuf promotes aPKC apical recycling until sufficient levels of active aPKC are reached. Thus, we provide a novel link between cell polarity regulation and traffic control in epithelia. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0253-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francisco J Calero-Cuenca
- CABD, CSIC/JA/UPO, Campus Universidad Pablo de Olavide, Ctra. De Utrera Km. 1, Seville, 41013, Spain
| | | | | | - María T Díaz-Meco
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - Jorge Moscat
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - Sol Sotillos
- CABD, CSIC/JA/UPO, Campus Universidad Pablo de Olavide, Ctra. De Utrera Km. 1, Seville, 41013, Spain.
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17
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Lin T, Pan PY, Lai YT, Chiang KW, Hsieh HL, Wu YP, Ke JM, Lee MC, Liao SS, Shih HT, Tang CY, Yang SB, Cheng HC, Wu JT, Jan YN, Lee HH. Spindle-F Is the Central Mediator of Ik2 Kinase-Dependent Dendrite Pruning in Drosophila Sensory Neurons. PLoS Genet 2015; 11:e1005642. [PMID: 26540204 PMCID: PMC4634852 DOI: 10.1371/journal.pgen.1005642] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 10/11/2015] [Indexed: 11/18/2022] Open
Abstract
During development, certain Drosophila sensory neurons undergo dendrite pruning that selectively eliminates their dendrites but leaves the axons intact. How these neurons regulate pruning activity in the dendrites remains unknown. Here, we identify a coiled-coil protein Spindle-F (Spn-F) that is required for dendrite pruning in Drosophila sensory neurons. Spn-F acts downstream of IKK-related kinase Ik2 in the same pathway for dendrite pruning. Spn-F exhibits a punctate pattern in larval neurons, whereas these Spn-F puncta become redistributed in pupal neurons, a step that is essential for dendrite pruning. The redistribution of Spn-F from puncta in pupal neurons requires the phosphorylation of Spn-F by Ik2 kinase to decrease Spn-F self-association, and depends on the function of microtubule motor dynein complex. Spn-F is a key component to link Ik2 kinase to dynein motor complex, and the formation of Ik2/Spn-F/dynein complex is critical for Spn-F redistribution and for dendrite pruning. Our findings reveal a novel regulatory mechanism for dendrite pruning achieved by temporal activation of Ik2 kinase and dynein-mediated redistribution of Ik2/Spn-F complex in neurons.
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Affiliation(s)
- Tzu Lin
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Yuan Pan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Ting Lai
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kai-Wen Chiang
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hsin-Lun Hsieh
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Ping Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jian-Ming Ke
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Myong-Chol Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shih-Sian Liao
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hsueh-Tzu Shih
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chiou-Yang Tang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Shi-Bing Yang
- Howard Hughes Medical Institute, Department of Physiology, Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Hsu-Chen Cheng
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yuh-Nung Jan
- Howard Hughes Medical Institute, Department of Physiology, Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Hsiu-Hsiang Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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18
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Otani T, Oshima K, Kimpara A, Takeda M, Abdu U, Hayashi S. A transport and retention mechanism for the sustained distal localization of Spn-F-IKKε during Drosophila bristle elongation. Development 2015; 142:2338-51. [PMID: 26092846 PMCID: PMC4510591 DOI: 10.1242/dev.121863] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 05/12/2015] [Indexed: 12/17/2022]
Abstract
Stable localization of the signaling complex is essential for the robust morphogenesis of polarized cells. Cell elongation involves molecular signaling centers that coordinately regulate intracellular transport and cytoskeletal structures. In Drosophila bristle elongation, the protein kinase IKKε is activated at the distal tip of the growing bristle and regulates the shuttling movement of recycling endosomes and cytoskeletal organization. However, how the distal tip localization of IKKε is established and maintained during bristle elongation is unknown. Here, we demonstrate that IKKε distal tip localization is regulated by Spindle-F (Spn-F), which is stably retained at the distal tip and functions as an adaptor linking IKKε to cytoplasmic dynein. We found that Javelin-like (Jvl) is a key regulator of Spn-F retention. In jvl mutant bristles, IKKε and Spn-F initially localize to the distal tip but fail to be retained there. In S2 cells, particles that stain positively for Jvl or Spn-F move in a microtubule-dependent manner, whereas Jvl and Spn-F double-positive particles are immobile, indicating that Jvl and Spn-F are transported separately and, upon forming a complex, immobilize each other. These results suggest that polarized transport and selective retention regulate the distal tip localization of the Spn-F–IKKε complex during bristle cell elongation. Summary: In the Drosophila bristle, the microtubule binding protein Jvl, the adaptor Spn-F and cytoplasmic dynein are required for localised transport and retention of polarised signalling factors.
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Affiliation(s)
- Tetsuhisa Otani
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Kenzi Oshima
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Akiyo Kimpara
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Michiko Takeda
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Uri Abdu
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel
| | - Shigeo Hayashi
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan Department of Biology, Kobe University Graduate School of Science, Kobe, Hyogo 657-8501, Japan
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19
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Yashiro H, Loza AJ, Skeath JB, Longmore GD. Rho1 regulates adherens junction remodeling by promoting recycling endosome formation through activation of myosin II. Mol Biol Cell 2014; 25:2956-69. [PMID: 25079692 PMCID: PMC4230585 DOI: 10.1091/mbc.e14-04-0894] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Once adherens junctions (AJs) are formed between polarized epithelial cells they must be maintained because AJs are constantly remodeled in dynamic epithelia. AJ maintenance involves endocytosis and subsequent recycling of E-cadherin to a precise location along the basolateral membrane. In the Drosophila pupal eye epithelium, Rho1 GTPase regulates AJ remodeling through Drosophila E-cadherin (DE-cadherin) endocytosis by limiting Cdc42/Par6/aPKC complex activity. We demonstrate that Rho1 also influences AJ remodeling by regulating the formation of DE-cadherin-containing, Rab11-positive recycling endosomes in Drosophila postmitotic pupal eye epithelia. This effect of Rho1 is mediated through Rok-dependent, but not MLCK-dependent, stimulation of myosin II activity yet independent of its effects upon actin remodeling. Both Rho1 and pMLC localize on endosomal vesicles, suggesting that Rho1 might regulate the formation of recycling endosomes through localized myosin II activation. This work identifies spatially distinct functions for Rho1 in the regulation of DE-cadherin-containing vesicular trafficking during AJ remodeling in live epithelia.
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Affiliation(s)
- Hanako Yashiro
- ICCE Institute, Washington University School of Medicine, St. Louis, MO 63110 Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110 Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110
| | - Andrew J Loza
- ICCE Institute, Washington University School of Medicine, St. Louis, MO 63110 Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110
| | - James B Skeath
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110
| | - Gregory D Longmore
- ICCE Institute, Washington University School of Medicine, St. Louis, MO 63110 Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110 Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 BRIGHT Institute, Washington University School of Medicine, St. Louis, MO 63110
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20
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dAcsl, the Drosophila ortholog of acyl-CoA synthetase long-chain family member 3 and 4, inhibits synapse growth by attenuating bone morphogenetic protein signaling via endocytic recycling. J Neurosci 2014; 34:2785-96. [PMID: 24553921 DOI: 10.1523/jneurosci.3547-13.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Fatty acid metabolism plays an important role in brain development and function. Mutations in acyl-CoA synthetase long-chain family member 4 (ACSL4), which converts long-chain fatty acids to acyl-CoAs, result in nonsyndromic X-linked mental retardation. ACSL4 is highly expressed in the hippocampus, a structure critical for learning and memory. However, the underlying mechanism by which mutations of ACSL4 lead to mental retardation remains poorly understood. We report here that dAcsl, the Drosophila ortholog of ACSL4 and ACSL3, inhibits synaptic growth by attenuating BMP signaling, a major growth-promoting pathway at neuromuscular junction (NMJ) synapses. Specifically, dAcsl mutants exhibited NMJ overgrowth that was suppressed by reducing the doses of the BMP pathway components, accompanied by increased levels of activated BMP receptor Thickveins (Tkv) and phosphorylated mothers against decapentaplegic (Mad), the effector of the BMP signaling at NMJ terminals. In addition, Rab11, a small GTPase involved in endosomal recycling, was mislocalized in dAcsl mutant NMJs, and the membrane association of Rab11 was reduced in dAcsl mutant brains. Consistently, the BMP receptor Tkv accumulated in early endosomes but reduced in recycling endosomes in dAcsl mutant NMJs. dAcsl was also required for the recycling of photoreceptor rhodopsin in the eyes, implying a general role for dAcsl in regulating endocytic recycling of membrane receptors. Importantly, expression of human ACSL4 rescued the endocytic trafficking and NMJ phenotypes of dAcsl mutants. Together, our results reveal a novel mechanism whereby dAcsl facilitates Rab11-dependent receptor recycling and provide insights into the pathogenesis of ACSL4-related mental retardation.
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21
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Van Acker T, Eyckerman S, Vande Walle L, Gerlo S, Goethals M, Lamkanfi M, Bovijn C, Tavernier J, Peelman F. The small GTPase Arf6 is essential for the Tram/Trif pathway in TLR4 signaling. J Biol Chem 2013; 289:1364-76. [PMID: 24297182 DOI: 10.1074/jbc.m113.499194] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Recognition of lipopolysaccharides (LPS) by Toll-like receptor 4 (TLR4) at the plasma membrane triggers NF-κB activation through recruitment of the adaptor proteins Mal and MyD88. Endocytosis of the activated TLR4 allows recruitment of the adaptors Tram and Trif, leading to activation of the transcription factor IRF3 and interferon production. The small GTPase ADP-ribosylation factor 6 (Arf6) was shown to regulate the plasma membrane association of Mal. Here we demonstrate that inhibition of Arf6 also markedly reduced LPS-induced cytokine production in Mal(-/-) mouse macrophages. In this article, we focus on a novel role for Arf6 in the MyD88-independent TLR4 pathway. MyD88-independent IRF3 activation and IRF3-dependent gene transcription were strictly dependent on Arf6. Arf6 was involved in transport of Tram to the endocytic recycling compartment and internalization of LPS, possibly explaining its requirement for LPS-induced IRF3 activation. Together, these results show a critical role for Arf6 in regulating Tram/Trif-dependent TLR4 signaling.
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Affiliation(s)
- Tim Van Acker
- From the Department of Medical Protein Research, Cytokine Receptor Lab, VIB, Ghent B-9000, Belgium
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22
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Drosophila oocyte polarity and cytoskeleton organization require regulation of Ik2 activity by Spn-F and Javelin-like. Mol Cell Biol 2013; 33:4371-80. [PMID: 24019068 DOI: 10.1128/mcb.00713-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Drosophila melanogaster Spn-F, Ik2, and Javelin-like (Jvl) proteins interact to regulate oocyte mRNA localization and cytoskeleton organization. However, the mechanism by which these proteins interact remains unclear. Using antibodies to activated Ik2, we showed that this protein is found at the region of oocyte and follicle cell where microtubule minus ends are enriched. We demonstrate that germ line Ik2 activation is diminished both in jvl and in spn-F mutant ovaries. Structure-function analysis of Spn-F revealed that the C-terminal end is critical for protein function, since it alone was able to rescue spn-F sterility. On the other hand, germ line expression of Spn-F lacking its conserved C-terminal region (Spn-FΔC) phenocopied ik2, leading to production of ventralized eggshell and bicaudal embryos. In Spn-FΔC-expressing oocytes, Gurken protein is mislocalized and oskar mRNA and protein localization is disrupted. Expression of Ik2 rescued Spn-FΔC ovarian phenotypes. We found that whereas Spn-F physically interacts with Ik2 and Jvl, Spn-FΔC physically interacts with Ik2 but not with Jvl. Thus, expression of Spn-FΔC, which lacks the Jvl-interacting domain, probably interferes with interaction of Ik2 and Jvl. In summary, our results demonstrate that Spn-F mediates the interaction between Ik2 and Jvl to control Ik2 activity.
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23
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Dong B, Kakihara K, Otani T, Wada H, Hayashi S. Rab9 and retromer regulate retrograde trafficking of luminal protein required for epithelial tube length control. Nat Commun 2013; 4:1358. [PMID: 23322046 PMCID: PMC3562448 DOI: 10.1038/ncomms2347] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 11/30/2012] [Indexed: 01/30/2023] Open
Abstract
Apical extracellular matrix filling the lumen controls the morphology and geometry of epithelial tubes during development, yet the regulation of luminal protein composition and its role in tube morphogenesis are not well understood. Here we show that an endosomal-retrieval machinery consisting of Rab9, retromer and actin nucleator WASH (Wiskott–Aldrich Syndrome Protein and SCAR Homolog) regulates selective recycling of the luminal protein Serpentine in the Drosophila trachea. Secreted Serpentine is endocytosed and sorted into the late endosome. Vps35, WASH and actin filaments differentially localize at the Rab9-enriched subdomains of the endosomal membrane, where Serpentine containing vesicles bud off. In Rab9, Vps35 and WASH mutants, Serpentine was secreted normally into the tracheal lumen, but the luminal quantities were depleted at later stages, resulting in excessively elongated tubes. In contrast, secretion of many luminal proteins was unaffected, suggesting that retrograde trafficking of a specific class of luminal proteins is a pivotal rate-limiting mechanism for continuous tube length regulation. The development of biological tubes is regulated by mutual interactions between cells and luminal extracellular matrix. Dong et al. show that retrograde recycling of luminal chitin deacetylase regulates Drosophila tracheal tubule geometry by restricting length independently of diameter.
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Affiliation(s)
- Bo Dong
- Laboratory for Morphogenetic Signaling, Riken Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Hyogo, Kobe 650-0047, Japan
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24
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Folker ES, Schulman VK, Baylies MK. Muscle length and myonuclear position are independently regulated by distinct Dynein pathways. Development 2012; 139:3827-37. [PMID: 22951643 DOI: 10.1242/dev.079178] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Various muscle diseases present with aberrant muscle cell morphologies characterized by smaller myofibers with mispositioned nuclei. The mechanisms that normally control these processes, whether they are linked, and their contribution to muscle weakness in disease, are not known. We examined the role of Dynein and Dynein-interacting proteins during Drosophila muscle development and found that several factors, including Dynein heavy chain, Dynein light chain and Partner of inscuteable, contribute to the regulation of both muscle length and myonuclear positioning. However, Lis1 contributes only to Dynein-dependent muscle length determination, whereas CLIP-190 and Glued contribute only to Dynein-dependent myonuclear positioning. Mechanistically, microtubule density at muscle poles is decreased in CLIP-190 mutants, suggesting that microtubule-cortex interactions facilitate myonuclear positioning. In Lis1 mutants, Dynein hyperaccumulates at the muscle poles with a sharper localization pattern, suggesting that retrograde trafficking contributes to muscle length. Both Lis1 and CLIP-190 act downstream of Dynein accumulation at the cortex, suggesting that they specify Dynein function within a single location. Finally, defects in muscle length or myonuclear positioning correlate with impaired muscle function in vivo, suggesting that both processes are essential for muscle function.
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Affiliation(s)
- Eric S Folker
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA
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25
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Cheng H, Ren T, Sun SC. New insight into the oncogenic mechanism of the retroviral oncoprotein Tax. Protein Cell 2012; 3:581-9. [PMID: 22865346 DOI: 10.1007/s13238-012-2047-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 06/07/2012] [Indexed: 12/29/2022] Open
Abstract
Human T cell leukemia virus type 1 (HTLV-1), an etiological factor that causes adult T cell leukemia and lymphoma (ATL), infects over 20 million people worldwide. About 1 million of HTLV-1-infected patients develop ATL, a highly aggressive non-Hodgkin's lymphoma without an effective therapy. The pX region of the HTLV-1 viral genome encodes an oncogenic protein, Tax, which plays a central role in transforming CD4+ T lymphocytes by deregulating oncogenic signaling pathways and promoting cell cycle progression. Expression of Tax following viral entry is critical for promoting survival and proliferation of human T cells and is required for initiation of oncogenesis. Tax exhibits diverse functions in host cells, and this oncoprotein primarily targets IκB kinase complex in the cytoplasm, resulting in persistent activation of NF-κB and upregulation of its responsive gene expressions that are crucial for T cell survival and cell cycle progression. We here review recent advances for the pathological roles of Tax in modulating IκB kinase activity. We also discuss our recent observation that Tax connects the IκB kinase complex to autophagy pathways. Understanding Tax-mediated pathogenesis will provide insights into development of new therapeutics in controlling HTLV-1-associated diseases.
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Affiliation(s)
- Hua Cheng
- Penn State Hershey Cancer Institute, Hershey, PA 17033, USA.
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26
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Gault WJ, Olguin P, Weber U, Mlodzik M. Drosophila CK1-γ, gilgamesh, controls PCP-mediated morphogenesis through regulation of vesicle trafficking. ACTA ACUST UNITED AC 2012; 196:605-21. [PMID: 22391037 PMCID: PMC3307696 DOI: 10.1083/jcb.201107137] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
CK1-γ/gilgamesh spatially limits the planar cell polarity–regulated process of trichome formation in Drosophila through its effect on polarized vesicle recycling. Cellular morphogenesis, including polarized outgrowth, promotes tissue shape and function. Polarized vesicle trafficking has emerged as a fundamental mechanism by which protein and membrane can be targeted to discrete subcellular domains to promote localized protrusions. Frizzled (Fz)/planar cell polarity (PCP) signaling orchestrates cytoskeletal polarization and drives morphogenetic changes in such contexts as the vertebrate body axis and external Drosophila melanogaster tissues. Although regulation of Fz/PCP signaling via vesicle trafficking has been identified, the interplay between the vesicle trafficking machinery and downstream terminal PCP-directed processes is less established. In this paper, we show that Drosophila CK1-γ/gilgamesh (gish) regulates the PCP-associated process of trichome formation through effects on Rab11-mediated vesicle recycling. Although the core Fz/PCP proteins dictate prehair formation broadly, CK1-γ/gish restricts nucleation to a single site. Moreover, CK1-γ/gish works in parallel with the Fz/PCP effector multiple wing hairs, which restricts prehair formation along the perpendicular axis to Gish. Our findings suggest that polarized Rab11-mediated vesicle trafficking regulated by CK1-γ is required for PCP-directed processes.
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Affiliation(s)
- William J Gault
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA
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Bitan A, Rosenbaum I, Abdu U. Stable and dynamic microtubules coordinately determine and maintain Drosophila bristle shape. Development 2012; 139:1987-96. [PMID: 22513371 DOI: 10.1242/dev.076893] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Within interphase cells, microtubules (MTs) are organized in a cell-specific manner to support cell shape and function. Here, we report that coordination between stable and dynamic MTs determines and maintains the highly elongated bristle cell shape. By following MT-decorating hooks and by tracking EB1 we identified two MT populations within bristles: a stable MT population polarized with their minus ends distal to the cell body, and a dynamic MT population that exhibits mixed polarity. Manipulating MT dynamics by Klp10A downregulation demonstrates that MTs can initiate new shaft extensions and thus possess the ability to determine growth direction. Actin filament bundling subsequently supports the newly formed shaft extensions. Analysis of ik2 mutant bristles, established by elongation defects in the Drosophila ikkε homolog, led to the observation that stable and dynamic MT orientation and polarized organization are important for proper bristle elongation. Thus, we demonstrate for the first time that coordination between stable and dynamic MT sets that are axially organized yet differently polarized drives cell elongation.
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Affiliation(s)
- Amir Bitan
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel
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Abdus-Saboor I, Stone CE, Murray JI, Sundaram MV. The Nkx5/HMX homeodomain protein MLS-2 is required for proper tube cell shape in the C. elegans excretory system. Dev Biol 2012; 366:298-307. [PMID: 22537498 DOI: 10.1016/j.ydbio.2012.03.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 03/26/2012] [Accepted: 03/28/2012] [Indexed: 01/20/2023]
Abstract
Cells perform wide varieties of functions that are facilitated, in part, by adopting unique shapes. Many of the genes and pathways that promote cell fate specification have been elucidated. However, relatively few transcription factors have been identified that promote shape acquisition after fate specification. Here we show that the Nkx5/HMX homeodomain protein MLS-2 is required for cellular elongation and shape maintenance of two tubular epithelial cells in the C. elegans excretory system, the duct and pore cells. The Nkx5/HMX family is highly conserved from sea urchins to humans, with known roles in neuronal and glial development. MLS-2 is expressed in the duct and pore, and defects in mls-2 mutants first arise when the duct and pore normally adopt unique shapes. MLS-2 cooperates with the EGF-Ras-ERK pathway to turn on the LIN-48/Ovo transcription factor in the duct cell during morphogenesis. These results reveal a novel interaction between the Nkx5/HMX family and the EGF-Ras pathway and implicate a transcription factor, MLS-2, as a regulator of cell shape.
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Affiliation(s)
- Ishmail Abdus-Saboor
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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Collins LL, Simon G, Matheson J, Wu C, Miller MC, Otani T, Yu X, Hayashi S, Prekeris R, Gould GW. Rab11-FIP3 is a cell cycle-regulated phosphoprotein. BMC Cell Biol 2012; 13:4. [PMID: 22401586 PMCID: PMC3310825 DOI: 10.1186/1471-2121-13-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 03/08/2012] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Rab11 and its effector molecule, Rab11-FIP3 (FIP3), associate with recycling endosomes and traffic into the furrow and midbody of cells during cytokinesis. FIP3 also controls recycling endosome distribution during interphase. Here, we examine whether phosphorylation of FIP3 is involved in these activities. RESULTS We identify four sites of phosphorylation of FIP3 in vivo, S-102, S-280, S-347 and S-450 and identify S-102 as a target for Cdk1-cyclin B in vitro. Of these, we show that S-102 is phosphorylated in metaphase and is dephosphorylated as cells enter telophase. Over-expression of FIP3-S102D increased the frequency of binucleate cells consistent with a role for this phospho-acceptor site in cytokinesis. Mutation of S-280, S-347 or S-450 or other previously identified phospho-acceptor sites (S-488, S-538, S-647 and S-648) was without effect on binucleate cell formation and did not modulate the distribution of FIP3 during the cell cycle. In an attempt to identify a functional role for FIP3 phosphorylation, we report that the change in FIP3 distribution from cytosolic to membrane-associated observed during progression from anaphase to telophase is accompanied by a concomitant dephosphorylation of FIP3. However, the phospho-acceptor sites identified here did not control this change in distribution. CONCLUSIONS Our data thus identify FIP3 as a cell cycle regulated phosphoprotein and suggest dephosphorylation of FIP3 accompanies its translocation from the cytosol to membranes during telophase. S102 is dephosphorylated during telophase; mutation of S102 exerts a modest effect on cytokinesis. Finally, we show that de/phosphorylation of the phospho-acceptor sites identified here (S-102, S-280, S-347 and S-450) is not required for the spatial control of recycling endosome distribution or function.
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Affiliation(s)
- Louise L Collins
- Henry Wellcome Laboratory of Cell Biology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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Nagaraj R, Adler PN. Dusky-like functions as a Rab11 effector for the deposition of cuticle during Drosophila bristle development. Development 2012; 139:906-16. [PMID: 22278919 DOI: 10.1242/dev.074252] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The morphogenesis of Drosophila sensory bristles is dependent on the function of their actin and microtubule cytoskeleton. Actin filaments are important for bristle shape and elongation, while microtubules are thought to mediate protein and membrane trafficking to promote growth. We have identified an essential role for the bristle cuticle in the maintenance of bristle structure and shape at late stages of bristle development. We show that the small GTPase Rab11 mediates the organized deposition of chitin, a major cuticle component in bristles, and disrupting Rab11 function leads to phenotypes that result from bristle collapse rather than a failure to elongate. We further establish that Rab11 is required for the plasma membrane localization of the ZP domain-containing Dusky-like (Dyl) protein and that Dyl is also required for cuticle formation in bristles. Our data argue that Dyl functions as a Rab11 effector for mediating the attachment of the bristle cell membrane to chitin to establish a stable cuticle. Our studies also implicate the exocyst as a Rab11 effector in this process and that Rab11 trafficking along the bristle shaft is mediated by microtubules.
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Affiliation(s)
- Ranganayaki Nagaraj
- Biology Department, Cell Biology Department, Institute for Morphogenesis and Regenerative Medicine, University of Virginia, Charlottesville, VA 22903, USA
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Abstract
Rab proteins are a family of small GTPases which, since their initial identification in the late 1980s, have emerged as master regulators of all stages of intracellular trafficking processes in eukaryotic cells. Rabs cycle between distinct conformations that are dependent on their guanine-nucleotide-bound status. When active (GTP-bound), Rabs are distributed to the cytosolic face of specific membranous compartments where they recruit downstream effector proteins. Rab-effector complexes then execute precise intracellular trafficking steps, which, in many cases, include vesicle motility. Microtubule-based kinesin and cytoplasmic dynein motor complexes are prominent among the classes of known Rab effector proteins. Additionally, many Rabs associate with microtubule-based motors via effectors that act as adaptor molecules that can simultaneously associate with the GTP-bound Rab and specific motor complexes. Thus, through association with motor complexes, Rab proteins can allow for membrane association and directional movement of various vesicular cargos along the microtubule cytoskeleton. In this mini-review, we highlight the expanding repertoire of Rab/microtubule motor protein interactions, and, in doing so, present an outline of the multiplicity of transport processes which result from such interactions.
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Pavarotti M, Capmany A, Vitale N, Colombo MI, Damiani MT. Rab11 is phosphorylated by classical and novel protein kinase C isoenzymes upon sustained phorbol ester activation. Biol Cell 2012; 104:102-15. [PMID: 22188018 DOI: 10.1111/boc.201100062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 11/29/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND INFORMATION Rab11 is a small GTPase that controls diverse intracellular trafficking pathways. However, the molecular machinery that regulates the participation of Rab11 in those different transport events is poorly understood. In resting cells, Rab11 localizes at the endocytic recycling compartment (ERC), whereas the different protein kinase C (PKC) isoforms display a cytosolic distribution. RESULTS Sustained phorbol ester stimulation induces the translocation of the classical PKCα and PKCβII isoenzymes to the ERC enriched in Rab11, and results in transferrin recycling inhibition. In contrast, novel PKCε and atypical PKCζ isoenzymes neither redistribute to the perinucleus nor modify transferrin recycling transport after phorbol ester stimulation. Although several Rabs have been shown to be phosphorylated, there is to date no evidence indicating Rab11 as a kinase substrate. In this report, we show that Rab11 appears phosphorylated in vivo in phorbol ester-stimulated cells. A bioinformatic analysis of Rab11 allowed us to identify several high-probability Ser/Thr kinase phosphorylation sites. Our results demonstrate that classical PKC (PKCα and PKCβII but not PKCβI) directly phosphorylate Rab11 in vitro. In addition, novel PKCε and PKCη but not PKCδ isoenzymes also phosphorylate Rab11. Mass spectrometry analysis revealed that Ser 177 is the Rab11 residue to be phosphorylated in vitro by either PKCβII or PKCε. In agreement, the phosphomimetic mutant, Rab11 S177D, retains transferrin at the ERC in the absence of phorbol-12-myristate-13-acetate stimulus. CONCLUSIONS This report shows for the first time that Rab11 is differentially phosphorylated by distinct PKC isoenzymes and that this post-translational modification might be a regulatory mechanism of intracellular trafficking.
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Affiliation(s)
- Martín Pavarotti
- IHEM-CONICET, National Research Council, School of Medicine, University of Cuyo, Mendoza, Argentina
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Dubin-Bar D, Bitan A, Bakhrat A, Amsalem S, Abdu U. Drosophila javelin-like encodes a novel microtubule-associated protein and is required for mRNA localization during oogenesis. Development 2011; 138:4661-71. [PMID: 21989913 DOI: 10.1242/dev.069161] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Asymmetrical localization of mRNA transcripts during Drosophila oogenesis determines the anteroposterior and dorsoventral axes of the Drosophila embryo. Correct localization of these mRNAs requires both microtubule (MT) and actin networks. In this study, we have identified a novel gene, CG43162, that regulates mRNA localization during oogenesis and also affects bristle development. We also showed that the Drosophila gene javelin-like, which was identified based on its bristle phenotype, is an allele of the CG43162 gene. We demonstrated that female mutants for jvl produce ventralized eggs owing to the defects in the localization and translation of gurken mRNA during mid-oogenesis. Mutations in jvl also affect oskar and bicoid mRNA localization. Analysis of cytoskeleton organization in the mutants reveal defects in both MT and actin networks. We showed that Jvl protein colocalizes with MT network in Schneider cells, in mammalian cells and in the Drosophila oocyte. Both in the oocyte and in the bristle cells, the protein localizes to a region where MT minus-ends are enriched. Jvl physically interacts with SpnF and is required for its localization. We found that overexpression of Jvl in the germline affects MT-dependent processes: oocyte growth and oocyte nucleus anchoring. Thus, our results show that we have identified a novel MT-associated protein that affects mRNA localization in the oocyte by regulating MT organization.
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Affiliation(s)
- Dikla Dubin-Bar
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel
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Neto H, Gould GW. The regulation of abscission by multi-protein complexes. J Cell Sci 2011; 124:3199-207. [DOI: 10.1242/jcs.083949] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The terminal stage of cytokinesis – a process termed abscission – is the severing of the thin intercellular bridge that connects the two daughter cells. Recent work provides new insight into the mechanism by which this microtubule-dense membrane bridge is resolved, and highlights important roles for multi-protein assemblies in different facets of abscission. These include the endosomal sorting complex required for transport (ESCRT), which appears to have a decisive role in the final scission event, and vesicle tethering complexes, which potentially act at an earlier stage, and might serve to prepare the abscission site. Here, we review recent studies of the structure, function and regulation of these complexes as related to abscission. We focus largely on studies of cytokinesis in mammalian cells. However, cell division in other systems, such as plants and Archae, is also considered, reflecting the mechanistic conservation of membrane-scission processes during cell division.
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Affiliation(s)
- Hélia Neto
- Henry Wellcome Laboratory of Cell Biology, Davidson Building, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Gwyn W. Gould
- Henry Wellcome Laboratory of Cell Biology, Davidson Building, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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The Drosophila javelin gene encodes a novel actin-associated protein required for actin assembly in the bristle. Mol Cell Biol 2011; 31:4582-92. [PMID: 21930794 DOI: 10.1128/mcb.05730-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Drosophila melanogaster bristle is a highly polarized cell that builds specialized cytoskeletal structures. Whereas actin is required for increasing bristle length, microtubules are essential for bristle axial growth. To identify new proteins involved in cytoskeleton organization during bristle development, we focused on identifying and characterizing the javelin (jv) locus. We found that in a jv mutant, the bristle tip is swollen and abnormal organization of bristle grooves is seen over the entire bristle. Using confocal and electron microscopy, we found that in jv mutant bristles, actin bundles do not form properly due to a loss of actin filaments within the bundle. We show that jv is an allele of the predicted CG32397 gene that encodes a protein with no homologs outside insects. Expression of the Jv protein fused to a green fluorescent protein (GFP) shows that the protein is colocalized with actin bundles in the bristle. Moreover, expression of Jv-GFP within the germ line led to the formation of ectopic actin bundles that surround the nucleus of nurse cells. Thus, we report that Jv is a novel actin-associated protein required for actin assembly during Drosophila bristle development.
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Abstract
The ability to coordinate membrane trafficking events in space and time is of fundamental importance in biology. Polarized trafficking is essential for processes as diverse as cytokinesis, regulated endocytosis, cell motility, and morphogenesis, yet the interface between cellular signaling systems and the trafficking machinery remains ill defined. Using Drosophila mechanosensory bristle growth as a paradigm for polarized trafficking, a study has uncovered a role for localized activation of the inhibitor of nuclear factor κB kinase, subtype ε (IKKε) at the tip of these bristles, where it regulates the trafficking of recycling endosomal vesicles into and out of the bristle tip. IKKε phosphorylates the Rab11 effector Nuf (which is encoded by nuclear fallout), and in doing so coordinates the interaction between Nuf and the motor protein dynein, which regulates the directionality of membrane traffic by a "motor-switching" mechanism. Similar results in mammalian systems suggest that IKKε-dependent phosphorylation of Rab11 effectors is an evolutionarily conserved mechanism by which cells may regulate polarized growth, and studies of vesicle trafficking in cytokinesis support the concept of motor switching as a generic mechanism to modulate the distribution of endosomes. Phosphorylation of other Rab11 effectors also modulates polarized trafficking in other experimental systems, which hints that similar mechanisms may be widely used to control the directionality of membrane traffic.
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Affiliation(s)
- Gwyn W Gould
- Henry Wellcome Laboratory of Cell Biology, Institute for Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, Davidson Building, University of Glasgow, Glasgow G12 8QQ, Scotland.
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