1
|
Sun D, Guo Y, Tang P, Li H, Chen L. Arf6 as a therapeutic target: Structure, mechanism, and inhibitors. Acta Pharm Sin B 2023; 13:4089-4104. [PMID: 37799386 PMCID: PMC10547916 DOI: 10.1016/j.apsb.2023.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/28/2023] [Accepted: 06/02/2023] [Indexed: 10/07/2023] Open
Abstract
ADP-ribosylation factor 6 (Arf6), a small G-protein of the Ras superfamily, plays pivotal roles in multiple cellular events, including exocytosis, endocytosis, actin remodeling, plasma membrane reorganization and vesicular transport. Arf6 regulates the progression of cancer through the activation of cell motility and invasion. Aberrant Arf6 activation is a potential therapeutic target. This review aims to understand the comprehensive function of Arf6 for future cancer therapy. The Arf6 GEFs, protein structure, and roles in cancer have been summarized. Comprehending the mechanism underlying Arf6-mediated cancer cell growth and survival is essential. The structural features of Arf6 and its efforts are discussed and may be contributed to the discovery of future novel protein-protein interaction inhibitors. In addition, Arf6 inhibitors and mechanism of action are listed in the table. This review further emphasizes the crucial roles in drug resistance and attempts to offer an outlook of Arf6 in cancer therapy.
Collapse
Affiliation(s)
- Dejuan Sun
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Yuanyuan Guo
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Piyu Tang
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Hua Li
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
- College of Pharmacy, Fujian University of Traditional Chinese Medicine, Fuzhou 350122, China
| | - Lixia Chen
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| |
Collapse
|
2
|
Ng B, Tasaki S, Greathouse KM, Walker CK, Zhang A, Covitz S, Cieslak M, Adamson AB, Andrade JP, Poovey EH, Curtis KA, Muhammad HM, Seidlitz J, Satterthwaite T, Bennett DA, Seyfried NT, Vogel J, Gaiteri C, Herskowitz JH. A Molecular Basis of Human Brain Connectivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.20.549895. [PMID: 37546752 PMCID: PMC10401931 DOI: 10.1101/2023.07.20.549895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Neuroimaging is commonly used to infer human brain connectivity, but those measurements are far-removed from the molecular underpinnings at synapses. To uncover the molecular basis of human brain connectivity, we analyzed a unique cohort of 98 individuals who provided neuroimaging and genetic data contemporaneous with dendritic spine morphometric, proteomic, and gene expression data from the superior frontal and inferior temporal gyri. Through cellular contextualization of the molecular data with dendritic spine morphology, we identified hundreds of proteins related to synapses, energy metabolism, and RNA processing that explain between-individual differences in functional connectivity and structural covariation. By integrating data at the genetic, molecular, subcellular, and tissue levels, we bridged the divergent fields of molecular biology and neuroimaging to identify a molecular basis of brain connectivity. One-Sentence Summary Dendritic spine morphometry and synaptic proteins unite the divergent fields of molecular biology and neuroimaging.
Collapse
|
3
|
EFA6 in Axon Regeneration, as a Microtubule Regulator and as a Guanine Nucleotide Exchange Factor. Cells 2021; 10:cells10061325. [PMID: 34073530 PMCID: PMC8226579 DOI: 10.3390/cells10061325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/23/2021] [Accepted: 05/24/2021] [Indexed: 11/17/2022] Open
Abstract
Axon regeneration after injury is a conserved biological process that involves a large number of molecular pathways, including rapid calcium influx at injury sites, retrograde injury signaling, epigenetic transition, transcriptional reprogramming, polarized transport, and cytoskeleton reorganization. Despite the numerous efforts devoted to understanding the underlying cellular and molecular mechanisms of axon regeneration, the search continues for effective target molecules for improving axon regeneration. Although there have been significant historical efforts towards characterizing pro-regenerative factors involved in axon regeneration, the pursuit of intrinsic inhibitors is relatively recent. EFA6 (exchange factor for ARF6) has been demonstrated to inhibit axon regeneration in different organisms. EFA6 inhibition could be a promising therapeutic strategy to promote axon regeneration and functional recovery after axon injury. This review summarizes the inhibitory role on axon regeneration through regulating microtubule dynamics and through affecting ARF6 (ADP-ribosylation factor 6) GTPase-mediated integrin transport.
Collapse
|
4
|
Wu CC, Brugeaud A, Seist R, Lin HC, Yeh WH, Petrillo M, Coppola G, Edge ASB, Stankovic KM. Altered expression of genes regulating inflammation and synaptogenesis during regrowth of afferent neurons to cochlear hair cells. PLoS One 2020; 15:e0238578. [PMID: 33001981 PMCID: PMC7529247 DOI: 10.1371/journal.pone.0238578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/19/2020] [Indexed: 12/20/2022] Open
Abstract
The spiral ganglion neurons constitute the primary connection between auditory hair cells and the brain. The spiral ganglion afferent fibers and their synapse with hair cells do not regenerate to any significant degree in adult mammalian ears after damage. We have investigated gene expression changes after kainate-induced disruption of the synapses in a neonatal cochlear explant model in which peripheral fibers and the afferent synapse do regenerate. We compared gene expression early after damage, during regeneration of the fibers and synapses, and after completion of in vitro regeneration. These analyses revealed a total of 2.5% differentially regulated transcripts (588 out of 24,000) based on a threshold of p<0.005. Inflammatory response genes as well as genes involved in regeneration of neural circuits were upregulated in the spiral ganglion neurons and organ of Corti, where the hair cells reside. Prominent genes upregulated at several time points included genes with roles in neurogenesis (Elavl4 and Sox21), neural outgrowth (Ntrk3 and Ppp1r1c), axonal guidance (Rgmb and Sema7a), synaptogenesis (Nlgn2 and Psd2), and synaptic vesicular function (Syt8 and Syn1). Immunohistochemical and in situ hybridization analysis of genes that had not previously been described in the cochlea confirmed their cochlear expression. The time course of expression of these genes suggests that kainate treatment resulted in a two-phase response in spiral ganglion neurons: an acute response consistent with inflammation, followed by an upregulation of neural regeneration genes. Identification of the genes activated during regeneration of these fibers suggests candidates that could be targeted to enhance regeneration in adult ears.
Collapse
Affiliation(s)
- Chen-Chi Wu
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Aurore Brugeaud
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Richard Seist
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Otorhinolaryngology-Head and Neck Surgery, Paracelsus Medical University, Salzburg, Austria
| | - Hsiao-Chun Lin
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Wei-Hsi Yeh
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marco Petrillo
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Giovanni Coppola
- Program in Neurogenetics, Department of Neurology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Albert S. B. Edge
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Konstantina M. Stankovic
- Eaton Peabody Laboratories and Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, United States of America
- Department of Otolaryngology—Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
- Harvard Program in Therapeutic Science, Harvard Medical School, Boston, Massachusetts, United States of America
| |
Collapse
|
5
|
Saegusa S, Fukaya M, Kakegawa W, Tanaka M, Katsumata O, Sugawara T, Hara Y, Itakura M, Okubo T, Sato T, Yuzaki M, Sakagami H. Mice lacking EFA6C/Psd2, a guanine nucleotide exchange factor for Arf6, exhibit lower Purkinje cell synaptic density but normal cerebellar motor functions. PLoS One 2019; 14:e0216960. [PMID: 31095630 PMCID: PMC6522047 DOI: 10.1371/journal.pone.0216960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/01/2019] [Indexed: 11/18/2022] Open
Abstract
ADP ribosylation factor 6 (Arf6) is a small GTPase that regulates various neuronal events including formation of the axon, dendrites and dendritic spines, and synaptic plasticity through actin cytoskeleton remodeling and endosomal trafficking. EFA6C, also known as Psd2, is a guanine nucleotide exchange factor for Arf6 that is preferentially expressed in the cerebellar cortex of adult mice, particularly in Purkinje cells. However, the roles of EFA6C in cerebellar development and functions remain unknown. In this study, we generated global EFA6C knockout (KO) mice using the CRISPR/Cas9 system and investigated their cerebellar phenotypes by histological and behavioral analyses. Histological analyses revealed that EFA6C KO mice exhibited normal gross anatomy of the cerebellar cortex, in terms of the thickness and cellularity of each layer, morphology of Purkinje cells, and distribution patterns of parallel fibers, climbing fibers, and inhibitory synapses. Electron microscopic observation of the cerebellar molecular layer revealed that the density of asymmetric synapses of Purkinje cells was significantly lower in EFA6C KO mice compared with wild-type control mice. However, behavioral analyses using accelerating rotarod and horizontal optokinetic response tests failed to detect any differences in motor coordination, learning or adaptation between the control and EFA6C KO mice. These results suggest that EFA6C plays ancillary roles in cerebellar development and motor functions.
Collapse
Affiliation(s)
- Shintaro Saegusa
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Wataru Kakegawa
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Manabu Tanaka
- Bio-imaging Center, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Osamu Katsumata
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Takeyuki Sugawara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Yoshinobu Hara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Makoto Itakura
- Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Tadashi Okubo
- Department of Laboratory Animal Science, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Toshiya Sato
- Department of Laboratory Animal Science, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Michisuke Yuzaki
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
- * E-mail:
| |
Collapse
|
6
|
Sztul E, Chen PW, Casanova JE, Cherfils J, Dacks JB, Lambright DG, Lee FJS, Randazzo PA, Santy LC, Schürmann A, Wilhelmi I, Yohe ME, Kahn RA. ARF GTPases and their GEFs and GAPs: concepts and challenges. Mol Biol Cell 2019; 30:1249-1271. [PMID: 31084567 PMCID: PMC6724607 DOI: 10.1091/mbc.e18-12-0820] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/26/2019] [Accepted: 03/11/2019] [Indexed: 12/12/2022] Open
Abstract
Detailed structural, biochemical, cell biological, and genetic studies of any gene/protein are required to develop models of its actions in cells. Studying a protein family in the aggregate yields additional information, as one can include analyses of their coevolution, acquisition or loss of functionalities, structural pliability, and the emergence of shared or variations in molecular mechanisms. An even richer understanding of cell biology can be achieved through evaluating functionally linked protein families. In this review, we summarize current knowledge of three protein families: the ARF GTPases, the guanine nucleotide exchange factors (ARF GEFs) that activate them, and the GTPase-activating proteins (ARF GAPs) that have the ability to both propagate and terminate signaling. However, despite decades of scrutiny, our understanding of how these essential proteins function in cells remains fragmentary. We believe that the inherent complexity of ARF signaling and its regulation by GEFs and GAPs will require the concerted effort of many laboratories working together, ideally within a consortium to optimally pool information and resources. The collaborative study of these three functionally connected families (≥70 mammalian genes) will yield transformative insights into regulation of cell signaling.
Collapse
Affiliation(s)
- Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, MA 01267
| | - James E. Casanova
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908
| | - Jacqueline Cherfils
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS and Ecole Normale Supérieure Paris-Saclay, 94235 Cachan, France
| | - Joel B. Dacks
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - David G. Lambright
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Amherst, MA 01605
| | - Fang-Jen S. Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | | | - Lorraine C. Santy
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Annette Schürmann
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Ilka Wilhelmi
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Marielle E. Yohe
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322-3050
| |
Collapse
|
7
|
Chomphoo S, Pakkarato S, Sawatpanich T, Sakagami H, Kondo H, Hipkaeo W. Localization of EFA6 (exchange factor for ARF6) isoform D in steroidogenic testicular Leydig cells of adult mice. Acta Histochem 2018; 120:263-268. [PMID: 29496264 DOI: 10.1016/j.acthis.2018.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 02/03/2018] [Accepted: 02/21/2018] [Indexed: 11/19/2022]
Abstract
EFA6 (exchange factor for ARF6) activates Arf6 (ADP ribosylation factor 6) by exchanging ADP to ATP and the resulting activated form of Arf6 is involved in the membrane trafficking and actin remodeling of cells. Our previous study has shown the selective expression/localization of EFA6D in steroidogenic adrenocortical cells in situ of adult mice. In view of the previous finding, the present study was undertaken to examine its localization in mouse Leydig cells representing another steroidogenic cell species in order to further support the possible involvement of the EFA6/Arf6 cascade via membrane trafficking in the regulation of steroidogenesis and/or secretion. A distinct band for EFA6D with the same size as that of the brain was detected in the testis of adult mice. In immuno-light microscopy, immunoreactivity for EFA6D was seen throughout the cytoplasm in most Leydig cells without any distinct accumulation along the plasmalemma. Lack of immunoreactivity for EFA6D was seen in the seminiferous tubular epithelium. In immuno-electron microscopy, the immune-labeling was seen in sporadic/focal patterns on plasma membranes and some vesicles and vacuoles subjacent to the plasma membranes. More constant and rather predominant is the labeling on numerous mitochondria. No immuno-labeling was seen in lipid droplets. The present study suggests that EFA6D is somehow involved in regulation of the synthesis and/or secretion of testosterone through the membrane-traffic by activation of Arf6. In addition, EFA6D is suggested to play in mitochondria some yet unidentified roles rather independent of Arf6-activation, which remains to be elucidated.
Collapse
Affiliation(s)
- Surang Chomphoo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Sawetree Pakkarato
- Department of Social Sciences, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Sura Narai Rd, Nai-muang, Muang, Nakhon Ratchasima 30000, Thailand
| | - Tarinee Sawatpanich
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Hiroyuki Sakagami
- Department of Anatomy, School of Medicine, Kitasato University, Tokyo, Japan
| | - Hisatake Kondo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Wiphawi Hipkaeo
- Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
| |
Collapse
|
8
|
Chen D, Yang C, Liu S, Hang W, Wang X, Chen J, Shi A. SAC-1 ensures epithelial endocytic recycling by restricting ARF-6 activity. J Cell Biol 2018; 217:2121-2139. [PMID: 29563216 PMCID: PMC5987724 DOI: 10.1083/jcb.201711065] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/06/2018] [Accepted: 02/28/2018] [Indexed: 11/22/2022] Open
Abstract
Arf6/ARF-6 is a crucial regulator of the endosomal phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) pool in endocytic recycling. To further characterize ARF-6 regulation, we performed an ARF-6 interactor screen in Caenorhabditis elegans and identified SAC-1, the homologue of the phosphoinositide phosphatase Sac1p in yeast, as a novel ARF-6 partner. In the absence of ARF-6, basolateral endosomes show a loss of SAC-1 staining in epithelial cells. Steady-state cargo distribution assays revealed that loss of SAC-1 specifically affected apical secretory delivery and basolateral recycling. PI(4,5)P2 levels and the endosomal labeling of the ARF-6 effector UNC-16 were significantly elevated in sac-1 mutants, suggesting that SAC-1 functions as a negative regulator of ARF-6. Further analyses revealed an interaction between SAC-1 and the ARF-6-GEF BRIS-1. This interaction outcompeted ARF-6(guanosine diphosphate [GDP]) for binding to BRIS-1 in a concentration-dependent manner. Consequently, loss of SAC-1 promotes the intracellular overlap between ARF-6 and BRIS-1. BRIS-1 knockdown resulted in a significant reduction in PI(4,5)P2 levels in SAC-1-depleted cells. Interestingly, the action of SAC-1 in sequestering BRIS-1 is independent of SAC-1's catalytic activity. Our results suggest that the interaction of SAC-1 with ARF-6 curbs ARF-6 activity by limiting the access of ARF-6(GDP) to its guanine nucleotide exchange factor, BRIS-1.
Collapse
Affiliation(s)
- Dan Chen
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Chao Yang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Sha Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Weijian Hang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xianghong Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Juan Chen
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Anbing Shi
- Department of Biochemistry and Molecular Biology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China .,Institute for Brain Research, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Key Laboratory of Neurological Disease of National Education Ministry, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| |
Collapse
|
9
|
Tachow A, Thoungseabyoun W, Phuapittayalert L, Petcharat K, Sakagami H, Kondo H, Hipkaeo W. Co-localization of endogenous Arf6 and its activator EFA6D in the granular convoluted tubule cells of mouse submandibular glands under normal conditions and when stimulated by isoproterenol, noradrenaline and carbachol. Arch Oral Biol 2017. [PMID: 28645101 DOI: 10.1016/j.archoralbio.2017.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE This study proposed to investigate the localization at light and electron microscopic levels of Arf6 and its activator EFA6D in the mouse submandibular gland (SMG) under normal conditions and when stimulated by adrenergic or cholinergic agonists. MATERIALS AND METHODS SMGs of male adult mice were utilized for immunoblotting and immuno-light and -electron microscopic analyses. Isoproterenol and noradrenalin were used as adrenergics, while carbachol was used for the cholinergic stimulant. SMGs were examined at 15, 30, 60 and 120min after intraperitoneal injection of these agents. RESULTS Immunoreactivities for both Arf6 and its activator EFA6D were similarly intense in the basolateral domain of GCTs, but no significant immunoreactivities were seen in the apical domain of GCT cells or any domain of acinar cells under normal conditions. In immuno-electron microscopy, the immunoreactive materials were mainly deposited on the basolateral plasma membranes and subjacent cytoplasm. Shortly after injection of isoproterenol and noradrenaline, but not carbachol, the immunoreactivities for both molecules were additionally seen on the apical plasmalemma of most, if not all, GCT cells, but not acinar cells. CONCLUSION The present findings suggest that the direct involvement of Arf6/EFA6D in regulatory exocytosis at the apical plasma membrane of acinar and GCT cells is apparently to be smaller, if present, than that of endocytosis at the basolateral membranes of GCT cells under normal conditions. This also suggests that the two molecules function additionally at the apical membrane of GCT cells for modulation of saliva secretion under β-adrenoceptor stimulation.
Collapse
Affiliation(s)
- Apussara Tachow
- Nanomorphology-Based Apply Research Group & Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Wipawee Thoungseabyoun
- Nanomorphology-Based Apply Research Group & Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | | | - Kanoktip Petcharat
- Biochemistry and Nutrition, School of Medical Science, University of Phayao, Phayao, Thailand
| | - Hiroyuki Sakagami
- Department of Anatomy, School of Medicine, Kitasato University, Tokyo, Japan
| | - Hisatake Kondo
- Nanomorphology-Based Apply Research Group & Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; Department of Organ Anatomy, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Wiphawi Hipkaeo
- Nanomorphology-Based Apply Research Group & Electron Microscopy Unit, Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
| |
Collapse
|
10
|
Fukaya M, Ohta S, Hara Y, Tamaki H, Sakagami H. Distinct subcellular localization of alternative splicing variants of EFA6D, a guanine nucleotide exchange factor for Arf6, in the mouse brain. J Comp Neurol 2016; 524:2531-52. [PMID: 27241101 DOI: 10.1002/cne.24048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/31/2016] [Accepted: 05/24/2016] [Indexed: 11/07/2022]
Abstract
EFA6D (guanine nucleotide exchange factor for ADP-ribosylation factor 6 [Arf6]D) is also known as EFA6R, Psd3, and HCA67. It is the fourth member of the EFA6 family with guanine nucleotide exchange activity for Arf6, a small guanosine triphosphatase (GTPase) that regulates endosomal trafficking and actin cytoskeleton remodeling. We propose a classification and nomenclature of 10 EFA6D variants deposited in the GenBank database as EFA6D1a, 1b, 1c, 1d, 1s, 2a, 2b, 2c, 2d, and 2s based on the combination of N-terminal and C-terminal insertions. Polymerase chain reaction analysis showed the expression of all EFA6D variants except for variants a and d in the adult mouse brain. Immunoblotting analysis with novel variant-specific antibodies showed the endogenous expression of EFA6D1b, EFA6D1c, and EFA6D1s at the protein level, with the highest expression being EFA6D1s, in the brain. Immunoblotting analysis of forebrain subcellular fractions showed the distinct subcellular distribution of EFA6D1b/c and EFA6D1s. The immunohistochemical analysis revealed distinct but overlapping immunoreactive patterns between EFA6D1b/c and EFA6D1s in the mouse brain. In immunoelectron microscopic analyses of the hippocampal CA3 region, EFA6D1b/c was present predominantly in the mossy fiber axons of dentate granule cells, whereas EFA6D1s was present abundantly in the cell bodies, dendritic shafts, and spines of hippocampal pyramidal cells. These results provide the first anatomical evidence suggesting the functional diversity of EFA6D variants, particularly EFA6D1b/c and EFA6D1s, in neurons. J. Comp. Neurol. 524:2531-2552, 2016. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, 252-0374, Japan
| | - Shingo Ohta
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, 252-0374, Japan
| | - Yoshinobu Hara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, 252-0374, Japan
| | - Hideaki Tamaki
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, 252-0374, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, 252-0374, Japan
| |
Collapse
|
11
|
Torii T, Miyamoto Y, Tago K, Sango K, Nakamura K, Sanbe A, Tanoue A, Yamauchi J. Arf6 guanine nucleotide exchange factor cytohesin-2 binds to CCDC120 and is transported along neurites to mediate neurite growth. J Biol Chem 2014; 289:33887-903. [PMID: 25326380 DOI: 10.1074/jbc.m114.575787] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of neurite growth is complicated, involving continuous cytoskeletal rearrangement and vesicular trafficking. Cytohesin-2 is a guanine nucleotide exchange factor for Arf6, an Arf family molecular switch protein, controlling cell morphological changes such as neuritogenesis. Here, we show that cytohesin-2 binds to a protein with a previously unknown function, CCDC120, which contains three coiled-coil domains, and is transported along neurites in differentiating N1E-115 cells. Transfection of the small interfering RNA (siRNA) specific for CCDC120 into cells inhibits neurite growth and Arf6 activation. When neurites start to extend, vesicles containing CCDC120 and cytohesin-2 are transported in an anterograde manner rather than a retrograde one. As neurites continue extension, anterograde vesicle transport decreases. CCDC120 knockdown inhibits cytohesin-2 localization into vesicles containing CCDC120 and diffuses cytohesin-2 in cytoplasmic regions, illustrating that CCDC120 determines cytohesin-2 localization in growing neurites. Reintroduction of the wild type CCDC120 construct into cells transfected with CCDC120 siRNA reverses blunted neurite growth and Arf6 activity, whereas the cytohesin-2-binding CC1 region-deficient CCDC120 construct does not. Thus, cytohesin-2 is transported along neurites by vesicles containing CCDC120, and it mediates neurite growth. These results suggest a mechanism by which guanine nucleotide exchange factor for Arf6 is transported to mediate neurite growth.
Collapse
Affiliation(s)
- Tomohiro Torii
- From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535,
| | - Yuki Miyamoto
- From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535
| | - Kenji Tago
- the Graduate School of Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498
| | - Kazunori Sango
- the Amyotrophic Lateral Sclerosis/Neuropathy Project, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506
| | - Kazuaki Nakamura
- From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535
| | - Atsushi Sanbe
- the School of Pharmacy, Iwate Medical University, Morioka, Iwate 020-0023, and
| | - Akito Tanoue
- From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535
| | - Junji Yamauchi
- From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535, the Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo 113-8510, Japan
| |
Collapse
|
12
|
Fukaya M, Fukushima D, Hara Y, Sakagami H. EFA6A, a guanine nucleotide exchange factor for Arf6, interacts with sorting nexin-1 and regulates neurite outgrowth. J Neurochem 2013; 129:21-36. [PMID: 24261326 DOI: 10.1111/jnc.12524] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/09/2013] [Accepted: 11/04/2013] [Indexed: 01/11/2023]
Abstract
The membrane trafficking and actin cytoskeleton remodeling mediated by ADP ribosylation factor 6 (Arf6) are functionally linked to various neuronal processes including neurite formation and maintenance, neurotransmitter release, and receptor internalization. EFA6A is an Arf6-specific guanine nucleotide exchange factor that is abundantly expressed in the brain. In this study, we identified sorting nexin-1 (SNX1), a retromer component that is implicated in endosomal sorting and trafficking, as a novel interacting partner for EFA6A by yeast two-hybrid screening. The interaction was mediated by the C-terminal region of EFA6A and a BAR domain of SNX1, and further confirmed by pull-down assay and immunoprecipitation from mouse brain lysates. In situ hybridization analysis demonstrated the widespread expression of SNX1 in the mouse brain, which overlapped with the expression of EFA6A in the forebrain. Immunofluorescent analysis revealed the partial colocalization of EFA6A and SNX1 in the dendritic fields of the hippocampus. Immunoelectron microscopic analysis revealed the overlapping subcellular localization of EFA6A and SNX1 at the post-synaptic density and endosomes in dendritic spines. In Neuro-2a neuroblastoma cells, expression of either EFA6A or SNX1 induced neurite outgrowth, which was further enhanced by co-expression of EFA6A and SNX1. The present findings suggest a novel mechanism by which EFA6A regulates Arf6-mediated neurite formation through the interaction with SNX1.
Collapse
Affiliation(s)
- Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | | | | | | |
Collapse
|
13
|
Hongu T, Kanaho Y. Activation machinery of the small GTPase Arf6. Adv Biol Regul 2013; 54:59-66. [PMID: 24139303 DOI: 10.1016/j.jbior.2013.09.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 09/11/2013] [Accepted: 09/12/2013] [Indexed: 11/17/2022]
Abstract
The small GTPase ADP-ribosylation factor 6 (Arf6) plays pivotal roles in a wide variety of cellular events, including exocytosis, endocytosis, actin cytoskeleton reorganization and phosphoinositide metabolism, in various types of cells. To control such a wide variety of actions of Arf6, activation of Arf6 could be precisely controlled by its activators, guanine nucleotide exchange factors (GEFs), in spatial and temporal manners. In this manuscript, we summarize and discuss the characteristics of previously identified GEFs specific to Arf6 and activation machineries of Arf6.
Collapse
Affiliation(s)
- Tsunaki Hongu
- Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Yasunori Kanaho
- Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| |
Collapse
|
14
|
Torii T, Miyamoto Y, Onami N, Tsumura H, Nemoto N, Kawahara K, Kato M, Kotera J, Nakamura K, Tanoue A, Yamauchi J. In vivo expression of the Arf6 Guanine-nucleotide exchange factor cytohesin-1 in mice exhibits enhanced myelin thickness in nerves. J Mol Neurosci 2013; 51:522-31. [PMID: 23636892 DOI: 10.1007/s12031-013-0018-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 04/19/2013] [Indexed: 12/17/2022]
Abstract
The myelin sheath consists of a unique multiple layer structure that acts as an insulator between neuronal axons to enhance the propagation of the action potential. In neuropathies such as demyelinating or dismyelinating diseases, chronic demyelination and defective remyelination occur repeatedly, leading to more severe neuropathy. As yet, little is known about the possibility of drug target-specific medicine for such diseases. In the developing peripheral nervous system (PNS), myelin sheaths form as Schwann cells wrap individual axons. It is thought that the development of a drug promoting myelination by Schwann cells would provide effective therapy against peripheral nerve disorders: to test such treatment, genetically modified mice overexpressing the drug target molecules are needed. We previously identified an Arf6 activator, the guanine-nucleotide exchange factor cytohesin-1, as the signaling molecule controlling myelination of peripheral axons by Schwann cells; yet, the important issue of whether cytohesin-1 itself promotes myelin thickness in vivo has remained unclear. Herein, we show that, in mouse PNS nerves, Schwann cell-specific expression of wild-type cytohesin-1 exhibits enhanced myelin thickness. Downstream activation of Arf6 is also seen in these transgenic mice, revealing the involvement of the cytohesin-1 and Arf6 signaling unit in promoting myelination. These results suggest that cytohesin-1 may be a candidate for the basis of a therapy for peripheral neuropathies through its enhancement of myelin thickness.
Collapse
Affiliation(s)
- Tomohiro Torii
- Molecular Pharmacology Group, Department of Pharmacology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Torii T, Miyamoto Y, Nakamura K, Maeda M, Yamauchi J, Tanoue A. Arf6 guanine-nucleotide exchange factor, cytohesin-2, interacts with actinin-1 to regulate neurite extension. Cell Signal 2012; 24:1872-82. [DOI: 10.1016/j.cellsig.2012.05.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 05/16/2012] [Accepted: 05/24/2012] [Indexed: 10/28/2022]
|
16
|
Théard D, Labarrade F, Partisani M, Milanini J, Sakagami H, Fon EA, Wood SA, Franco M, Luton F. USP9x-mediated deubiquitination of EFA6 regulates de novo tight junction assembly. EMBO J 2010; 29:1499-509. [PMID: 20339350 DOI: 10.1038/emboj.2010.46] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 03/03/2010] [Indexed: 11/09/2022] Open
Abstract
In epithelial cells, the tight junction (TJ) functions as a permeability barrier and is involved in cellular differentiation and proliferation. Although many TJ proteins have been characterized, little is known about the sequence of events and temporal regulation of TJ assembly in response to adhesion cues. We report here that the deubiquitinating enzyme USP9x has a critical function in TJ biogenesis by controlling the levels of the exchange factor for Arf6 (EFA6), a protein shown to facilitate TJ formation, during a narrow temporal window preceding the establishment of cell polarity. At steady state, EFA6 is constitutively ubiquitinated and turned over by the proteasome. However, at newly forming contacts, USP9x-mediated deubiquitination protects EFA6 from proteasomal degradation, leading to a transient increase in EFA6 levels. Consistent with this model, USP9x and EFA6 transiently co-localize at primordial epithelial junctions. Furthermore, knockdown of either EFA6 or USP9x impairs TJ biogenesis and EFA6 overexpression rescues TJ biogenesis in USP9x-knockdown cells. As the loss of cell polarity is a critical event in the metastatic spread of cancer, these findings may help to understand the pathology of human carcinomas.
Collapse
Affiliation(s)
- Delphine Théard
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, Valbonne, France
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Sironi C, Teesalu T, Muggia A, Fontana G, Marino F, Savaresi S, Talarico D. EFA6A encodes two isoforms with distinct biological activities in neuronal cells. J Cell Sci 2009; 122:2108-18. [DOI: 10.1242/jcs.042325] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The processes of neurite extension and remodeling require a close coordination between the cytoskeleton and the cell membranes. The small GTPase ARF6 (ADP-ribosylation factor 6) has a central role in regulating membrane traffic and actin dynamics, and its activity has been demonstrated to be involved in neurite elaboration. EFA6A has been shown to act as a guanine nucleotide exchange factor (GEF) for ARF6. Here, we report that two distinct isoforms of the EFA6A gene are expressed in murine neural tissue: a long isoform of 1025 amino acids (EFA6A), and a short isoform of 393 amino acids (EFA6As). EFA6A encompasses proline-rich regions, a Sec7 domain (mediating GEF activity on ARF6), a PH domain, and a C-terminal region with coiled-coil motifs. EFA6As lacks the Sec7 domain, and it comprises the PH domain and the C-terminal region. The transcript encoding EFA6As is the result of alternative promoter usage. EFA6A and EFA6As have distinct biological activities: upon overexpression in HeLa cells, EFA6A induces membrane ruffles, whereas EFA6As gives rise to cell elongation; in primary cortical neurons EFA6A promotes neurite extension, whereas EFA6As induces dendrite branching. Our findings suggest that EFA6A could participate in neuronal morphogenesis through the regulated expression of two functionally distinct isoforms.
Collapse
Affiliation(s)
- Cristina Sironi
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Tambet Teesalu
- Vascular Mapping Center, Burnham Institute for Medical Research at University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Anna Muggia
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Gabriele Fontana
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Fortunata Marino
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Sara Savaresi
- Department of Biochemistry, University of Zürich, Winterthurer Strasse 190, 8057 Zürich, CH, Switzerland
| | - Daniela Talarico
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| |
Collapse
|
18
|
Nekhoroshkova E, Albert S, Becker M, Rapp UR. A-RAF kinase functions in ARF6 regulated endocytic membrane traffic. PLoS One 2009; 4:e4647. [PMID: 19247477 PMCID: PMC2645234 DOI: 10.1371/journal.pone.0004647] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 01/13/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND RAF kinases direct ERK MAPK signaling to distinct subcellular compartments in response to growth factor stimulation. METHODOLOGY/PRINCIPAL FINDINGS Of the three mammalian isoforms A-RAF is special in that one of its two lipid binding domains mediates a unique pattern of membrane localization. Specific membrane binding is retained by an N-terminal fragment (AR149) that corresponds to a naturally occurring splice variant termed DA-RAF2. AR149 colocalizes with ARF6 on tubular endosomes and has a dominant negative effect on endocytic trafficking. Moreover actin polymerization of yeast and mammalian cells is abolished. AR149/DA-RAF2 does not affect the internalization step of endocytosis, but trafficking to the recycling compartment. CONCLUSIONS/SIGNIFICANCE A-RAF induced ERK activation is required for this step by activating ARF6, as A-RAF depletion or inhibition of the A-RAF controlled MEK-ERK cascade blocks recycling. These data led to a new model for A-RAF function in endocytic trafficking.
Collapse
Affiliation(s)
- Elena Nekhoroshkova
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
| | - Stefan Albert
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
| | - Matthias Becker
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
| | - Ulf R. Rapp
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), University of Würzburg, Würzburg, Germany
- * E-mail:
| |
Collapse
|
19
|
Localization of EFA6A, a guanine nucleotide exchange factor for ARF6, in spermatogenic cells of testes of adult mice. J Mol Histol 2008; 40:77-80. [PMID: 19085064 DOI: 10.1007/s10735-008-9207-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 11/26/2008] [Indexed: 11/27/2022]
Abstract
ADP ribosylation factors (ARFs) of small GTPase are molecular switches regulating various membrane dynamics. Among them, ARF6 has recently been highlighted because of its function to facilitate the interaction between the cytoskeleton and the plasma membrane. Each ARFs has its preferable or even specific guanine nucleotide exchange factors (GEFs) as its activators. According to our previous RT-PCR analysis, EFA6A, a guanine nucleotide exchange factor for ARF6, was restrictedly expressed in the brain, retina and testis. Different from previous studies on neurons, EFA6A, a guanine nucleotide exchange factor for ARF6, was first shown to be localized intensely in nuclei of spermatocytes of adult mouse testes in the present immunohistochemical study. This suggests a possible involvement of EFA6A-ARF6 signaling in the karyokinesis and cytokinesis.
Collapse
|
20
|
Sakagami H. The EFA6 family: guanine nucleotide exchange factors for ADP ribosylation factor 6 at neuronal synapses. TOHOKU J EXP MED 2008; 214:191-8. [PMID: 18323689 DOI: 10.1620/tjem.214.191] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
ADP ribosylation factor 6 (ARF6) is a member of the ARF family of small GTPases, which mediates a variety of neuronal functions accompanying the structural changes of developing and mature neurons through its regulation of actin cytoskeleton reorganization and membrane traffic. The activation of ARF6 is strictly regulated by guanine nucleotide exchange factors (GEFs). The EFA6 family is the first member that was identified to be a specific GEF for ARF6 and comprises four structurally related polypeptides (EFA6A, EFA6B, EFA6C and EFA6D). Since the cellular and subcelllular localization of GEFs is a critical determinant for the spatiotemporal activation of ARF6 in neurons, I have focused on the EFA6 family from the anatomical point of view to understand the neuronal functions of ARF6. Three members of the EFA6 family (EFA6A, EFA6C and EFA6D) are abundantly expressed in the mouse brain with distinct spatiotemporal patterns. Interestingly, they are enriched particularly in the postsynaptic density fraction, shedding light on the importance of the EFA-ARF6 pathway in neuronal synapses. Here, I will review the recent advances in the expression and functions of the EFA6 family in the nervous system.
Collapse
|
21
|
IQ-ArfGEF/BRAG1 is a guanine nucleotide exchange factor for Arf6 that interacts with PSD-95 at postsynaptic density of excitatory synapses. Neurosci Res 2007; 60:199-212. [PMID: 18164504 DOI: 10.1016/j.neures.2007.10.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 11/20/2022]
Abstract
ADP ribosylation factor 6 (Arf6) is a small GTPase that regulates dendritic differentiation possibly through the organization of actin cytoskeleton and membrane traffic. Here, we characterized IQ-ArfGEF/BRAG1, a guanine nucleotide exchange factor (GEF) for Arf6, in the mouse brain. In vivo Arf pull down assay demonstrated that IQ-ArfGEF/BRAG1 activated Arf6 more potently than Arf1. IQ-ArfGEF/BRAG1 mRNA was abundantly expressed in the brain with higher levels in forebrain structures and cerebellar granule cells. In hippocampal neurons, IQ-ArfGEF/BRAG1 mRNA was localized not only at neuronal cell bodies but also at dendritic processes, indicating its dendritic transport and localization. Immunoprecipitation and in vitro binding experiments revealed that IQ-ArfGEF/BRAG1 formed a protein complex with N-methyl-d-aspartate (NMDA)-type glutamate receptors through the interaction with a postsynaptic density (PSD) scaffold protein, PSD-95. Immunohistochemical analysis demonstrated that IQ-ArfGEF/BRAG1 was localized preferentially at the postsynaptic density of asymmetrical synapses on dendritic spines, but was lacking at GABAa receptor-carrying inhibitory synapses. Taken together, IQ-ArfGEF/BRAG1 forms a postsynaptic protein complex containing PSD-95 and NMDA receptors at excitatory synapses, where it may function as a GEF for Arf6.
Collapse
|
22
|
Kolanus W. Guanine nucleotide exchange factors of the cytohesin family and their roles in signal transduction. Immunol Rev 2007; 218:102-13. [PMID: 17624947 DOI: 10.1111/j.1600-065x.2007.00542.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Members of the cytohesin protein family, a group of guanine nucleotide exchange factors for adenosine diphosphate ribosylation factor (ARF) guanosine triphosphatases, have recently emerged as important regulators of signal transduction in vertebrate and invertebrate biology. These proteins share a modular domain structure, comprising carboxy-terminal membrane recruitment elements, a Sec7 homology effector domain, and an amino-terminal coiled-coil domain that serve as a platform for their integration into larger signaling complexes. Although these proteins have a highly similar overall build, their individual biological functions appear to be at least partly specific. Cytohesin-1 had been identified as a regulator of beta2 integrin inside-out regulation in immune cells and was subsequently shown to be involved in mitogen-associated protein kinase signaling in tumor cell proliferation as well as in T-helper cell activation and differentiation. Cytohesin-3, which had been discovered to be strongly associated with T-cell anergy, was very recently described as an essential component of insulin signal transduction in Drosophila and in human and murine liver cells. Future work will aim to dissect the mechanistic details of the modes of action of the cytohesins as well as to define the precise roles of these versatile proteins in vertebrates at the genetic level.
Collapse
Affiliation(s)
- Waldemar Kolanus
- Laboratory of Molecular Immunology, Program Unit Molecular Immune and Cell Biology, LIMES (Life and Medical Sciences Bonn), University of Bonn, Bonn, Germany.
| |
Collapse
|
23
|
Jaworski J. ARF6 in the nervous system. Eur J Cell Biol 2007; 86:513-24. [PMID: 17559968 DOI: 10.1016/j.ejcb.2007.04.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 04/11/2007] [Accepted: 04/18/2007] [Indexed: 01/19/2023] Open
Abstract
Actin cytoskeleton dynamics and membrane trafficking are tightly connected and are among the most important driving forces of neuronal development, basic synaptic transmission events, and synaptic plasticity. One group of proteins involved in coordination of these two processes is the family of ADP ribosylation factors (ARFs) regulating actin dynamics, lipid modification and membrane trafficking. ARF6 is the only member of the ARF family that can simultaneously regulate actin cytoskeleton changes and membrane exchange between plasma membrane and endocytic compartments. The presence of ARF6 and its guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) in the brain, as well as its capability to regulate several aspects of neuronal development and synaptic plasticity, has been recently demonstrated. The main purpose of this review is to present the current knowledge about how ARF6 can influence morphological processes crucial for proper formation of the neuronal circuits in the brain, including dendrite and axon differentiation, development of dendritic arbor complexity and dendritic spine formation. Potential effects of ARF6 on synaptic events resulting from its ability to control exo- and endocytosis will be also discussed.
Collapse
Affiliation(s)
- Jacek Jaworski
- Laboratory of Molecular and Cell Neurobiology, International Institute of Molecular and Cell Biology, Ks. Trojdena St. 4, PL-02-109, Warsaw, Poland.
| |
Collapse
|
24
|
Sakagami H, Honma T, Sukegawa J, Owada Y, Yanagisawa T, Kondo H. Somatodendritic localization of EFA6A, a guanine nucleotide exchange factor for ADP-ribosylation factor 6, and its possible interaction with α-actinin in dendritic spines. Eur J Neurosci 2007; 25:618-28. [PMID: 17298598 DOI: 10.1111/j.1460-9568.2007.05345.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
EFA6A is a member of the guanine nucleotide exchange factors that can specifically activate ADP ribosylation factor 6 (ARF6). In this study, we identified alpha-actinin-1 as a possible interacting protein with EFA6A by the yeast two-hybrid screening with its C-terminal region as bait. The central region of alpha-actinin-1 containing a part of spectrin repeat 1 and spectrin repeats 2-3 is responsible for this interaction. In the hippocampal formation, EFA6A immunoreactivity occurred at a high level as numerous fine puncta in the strata oriens, radiatum, lacunosum-moleculare of the hippocampal CA1-3 subfields and the dentate molecular layer, whereas the immunoreactivity was faint in the neuronal cell layers and the stratum lucidum, the mossy fiber-recipient layer of the CA3 subfield. Double-immunofluorescent analyses revealed a partial overlapping of EFA6A and alpha-actinin at the dendritic spines of in vivo and cultured hippocampal neurons. Our present findings suggest that EFA6A may form a protein complex with alpha-actinin and activate ARF6 in close proximity of the actin cytoskeleton and membrane proteins in the dendritic spines.
Collapse
Affiliation(s)
- Hiroyuki Sakagami
- Division of Histology, Department of Cell Biology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan.
| | | | | | | | | | | |
Collapse
|
25
|
Abstract
The ADP-ribosylation factor (ARF) small GTPases regulate vesicular traffic and organelle structure by recruiting coat proteins, regulating phospholipid metabolism and modulating the structure of actin at membrane surfaces. Recent advances in our understanding of the signalling pathways that are regulated by ARF1 and ARF6, two of the best characterized ARF proteins, provide a molecular context for ARF protein function in fundamental biological processes, such as secretion, endocytosis, phagocytosis, cytokinesis, cell adhesion and tumour-cell invasion.
Collapse
Affiliation(s)
- Crislyn D'Souza-Schorey
- Department of Biological Sciences and the Walther Cancer Institute, University of Notre Dame, Notre Dame, Indiana, USA.
| | | |
Collapse
|
26
|
Choi S, Ko J, Lee JR, Lee HW, Kim K, Chung HS, Kim H, Kim E. ARF6 and EFA6A regulate the development and maintenance of dendritic spines. J Neurosci 2006; 26:4811-9. [PMID: 16672654 PMCID: PMC6674147 DOI: 10.1523/jneurosci.4182-05.2006] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The cellular and molecular mechanisms underlying the development and maintenance of dendritic spines are not fully understood. ADP-ribosylation factor 6 (ARF6) is a small GTPase known to regulate actin remodeling and membrane traffic. Here, we report involvement of ARF6 and exchange factor for ARF6 (EFA6A) in the regulation of spine development and maintenance. An active form of ARF6 promotes the formation of dendritic spines at the expense of filopodia. EFA6A promotes spine formation in an ARF6 activation-dependent manner. Knockdown of ARF6 and EFA6A by small interfering RNA decreases spine formation. Live imaging indicates that ARF6 knockdown decreases the conversion of filopodia to spines and the stability of early spines. The spine-promoting effect of ARF6 is partially blocked by Rac1. ARF6 and EFA6A protect mature spines from inactivity-induced destabilization. These results suggest that ARF6 and EFA6A may regulate the conversion of filopodia to spines and the stability of both early and mature spines.
Collapse
|
27
|
Sakagami H, Suzuki H, Kamata A, Owada Y, Fukunaga K, Mayanagi H, Kondo H. Distinct spatiotemporal expression of EFA6D, a guanine nucleotide exchange factor for ARF6, among the EFA6 family in mouse brain. Brain Res 2006; 1093:1-11. [PMID: 16707115 DOI: 10.1016/j.brainres.2006.02.058] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Revised: 01/30/2006] [Accepted: 02/13/2006] [Indexed: 11/29/2022]
Abstract
The EFA6 family is a member of guanine nucleotide exchange factors (GEFs) that can activate ARF6 specifically in vitro. In this study, we determined the complete primary sequence of mouse EFA6D encoding a protein of 1004 amino acids with a calculated molecular weight of 111,207 Da. In ARF pull-down assay, EFA6D showed a preferential GEF activity toward ARF6. RT-PCR analysis revealed the widespread tissue distribution of EFA6D and the high expression of EFA6A, C and D in the brain. In situ hybridization analysis demonstrated a distinct spatiotemporal expression pattern of EFA6D from those of EFA6A and C in mouse brain. Furthermore, immunoblot analysis revealed that EFA6D was highly concentrated in the postsynaptic density fraction. These findings suggest differential spatiotemporal regulation of ARF6 by three members of the EFA6 family in the brain.
Collapse
Affiliation(s)
- Hiroyuki Sakagami
- Division of Histology, Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai 980-8574, Japan.
| | | | | | | | | | | | | |
Collapse
|
28
|
Vitaliani R, Mason W, Ances B, Zwerdling T, Jiang Z, Dalmau J. Paraneoplastic encephalitis, psychiatric symptoms, and hypoventilation in ovarian teratoma. Ann Neurol 2005; 58:594-604. [PMID: 16178029 PMCID: PMC2245881 DOI: 10.1002/ana.20614] [Citation(s) in RCA: 373] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report four young women who developed acute psychiatric symptoms, seizures, memory deficits, decreased level of consciousness, and central hypoventilation associated with ovarian teratoma (OT) and cerebrospinal fluid (CSF) inflammatory abnormalities. Three patients recovered with treatment of the tumor or immunosuppression and one died of the disorder. Five other OT patients with a similar syndrome and response to treatment have been reported. Our patients' serum or CSF showed immunolabeling of antigens that were expressed at the cytoplasmic membrane of hippocampal neurons and processes and readily accessed by antibodies in live neurons. Immunoprobing of a hippocampal-expression library resulted in the isolation of EFA6A, a protein that interacts with a member of the two-pore-domain potassium channel family and is involved in the regulation of the dendritic development of hippocampal neurons. EFA6A-purified antibodies reproduced the hippocampal immunolabeling of all patients' antibodies and colocalized with them at the plasma membrane. These findings indicate that in a young woman with acute psychiatric symptoms, seizures, and central hypoventilation, a paraneoplastic immune-mediated syndrome should be considered. Recognition of this disorder is important because despite the severity of the symptoms, patients usually recover. The location and function of the isolated antigen suggest that the disorder is directly mediated by antibodies.
Collapse
Affiliation(s)
- Roberta Vitaliani
- Division of Neuro-oncology, Department of Neurology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | |
Collapse
|
29
|
Matsuya S, Sakagami H, Tohgo A, Owada Y, Shin HW, Takeshima H, Nakayama K, Kokubun S, Kondo H. Cellular and subcellular localization of EFA6C, a third member of the EFA6 family, in adult mouse Purkinje cells. J Neurochem 2005. [DOI: 10.1111/j.1471-4159.2005.03421.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|