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Mohr I, Mirzaiebadizi A, Sanyal SK, Chuenban P, Ahmadian MR, Ivanov R, Bauer P. Characterization of the small Arabidopsis thaliana GTPase and ADP-ribosylation factor-like 2 protein TITAN 5. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.04.27.538563. [PMID: 37162876 PMCID: PMC10168340 DOI: 10.1101/2023.04.27.538563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Small GTPases function by conformational switching ability between GDP- and GTP-bound states in rapid cell signaling events. The ADP-ribosylation factor (ARF) family is involved in vesicle trafficking. Though evolutionarily well conserved, little is known about ARF and ARF-like GTPases in plants. Here, we characterized biochemical properties and cellular localization of the essential small ARF-like GTPase TITAN 5/HALLIMASCH/ARL2/ARLC1 (hereafter termed TTN5) from Arabidopsis thaliana. Two TTN5 variants were included in the study with point mutations at conserved residues, suspected to be functional for nucleotide exchange and GTP hydrolysis, TTN5T30N and TTN5Q70L. We found that TTN5 had a very rapid intrinsic nucleotide exchange capacity with a conserved nucleotide switching mechanism. TTN5 acted as a non-classical small GTPase with a remarkably low GTP hydrolysis activity, suggesting it is likely present in GTP-loaded active form in the cell. We analyzed signals from yellow fluorescent protein (YFP)-tagged TTN5 and from in situ immunolocalization of hemagglutine-tagged HA3-TTN5 in Arabidopsis seedlings and in a transient expression system. Together with colocalization using endomembrane markers and pharmacological treatments the microscopic analysis suggests that TTN5 can be present at the plasma membrane and dynamically associated with membranes of vesicles, Golgi stacks and multivesicular bodies. While the TTN5Q70L variant showed similar GTPase activities and localization behavior as wild-type TTN5, the TTN5T30N mutant differed in some aspects. Hence, the unusual capacity of rapid nucleotide exchange activity of TTN5 is linked with cell membrane dynamics, likely associated with vesicle transport pathways in the endomembrane system.
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Affiliation(s)
- Inga Mohr
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Amin Mirzaiebadizi
- Institute of Biochemistry and Molecular Biology II, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Sibaji K Sanyal
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Pichaporn Chuenban
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Mohammad R Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Petra Bauer
- Institute of Botany, Heinrich Heine University, 40225 Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences, Heinrich Heine University, 40225 Düsseldorf, Germany
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2
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Li T, Guo Y. ADP-Ribosylation Factor Family of Small GTP-Binding Proteins: Their Membrane Recruitment, Activation, Crosstalk and Functions. Front Cell Dev Biol 2022; 10:813353. [PMID: 35186926 PMCID: PMC8850633 DOI: 10.3389/fcell.2022.813353] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
Members of the ADP-ribosylation factor (ARF) family of guanine-nucleotide binding proteins play critical roles in various cellular processes, especially in regulating the secretory, and endocytic pathways. The fidelity of intracellular vesicular trafficking depends on proper activations and precise subcellular distributions of ARF family proteins regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Here we review recent progress in understanding the membrane recruitment, activation, crosstalk, and functions of ARF family proteins.
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Affiliation(s)
- Tiantian Li
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China
| | - Yusong Guo
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China
- Hong Kong University of Science and Technology, Shenzhen Research Institute, Shenzhen, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- *Correspondence: Yusong Guo,
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Kim HJ, Kim B, Byun HJ, Yu L, Nguyen TM, Nguyen TH, Do PA, Kim EJ, Cheong KA, Kim KS, Huy Phùng H, Rahman M, Jang JY, Rho SB, Kang GJ, Park MK, Lee H, Lee K, Cho J, Han HK, Kim SG, Lee AY, Lee CH. Resolvin D1 Suppresses H 2O 2-Induced Senescence in Fibroblasts by Inducing Autophagy through the miR-1299/ARG2/ARL1 Axis. Antioxidants (Basel) 2021; 10:1924. [PMID: 34943028 PMCID: PMC8750589 DOI: 10.3390/antiox10121924] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/24/2021] [Accepted: 11/28/2021] [Indexed: 12/15/2022] Open
Abstract
ARG2 has been reported to inhibit autophagy in vascular endothelial cells and keratinocytes. However, studies of its mechanism of action, its role in skin fibroblasts, and the possibility of promoting autophagy and inhibiting cellular senescence through ARG2 inhibition are lacking. We induced cellular senescence in dermal fibroblasts by using H2O2. H2O2-induced fibroblast senescence was inhibited upon ARG2 knockdown and promoted upon ARG2 overexpression. The microRNA miR-1299 suppressed ARG2 expression, thereby inhibiting fibroblast senescence, and miR-1299 inhibitors promoted dermal fibroblast senescence by upregulating ARG2. Using yeast two-hybrid assay, we found that ARG2 binds to ARL1. ARL1 knockdown inhibited autophagy and ARL1 overexpression promoted it. Resolvin D1 (RvD1) suppressed ARG2 expression and cellular senescence. These data indicate that ARG2 stimulates dermal fibroblast cell senescence by inhibiting autophagy after interacting with ARL1. In addition, RvD1 appears to promote autophagy and inhibit dermal fibroblast senescence by inhibiting ARG2 expression. Taken together, the miR-1299/ARG2/ARL1 axis emerges as a novel mechanism of the ARG2-induced inhibition of autophagy. Furthermore, these results indicate that miR-1299 and pro-resolving lipids, including RvD1, are likely involved in inhibiting cellular senescence by inducing autophagy.
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Affiliation(s)
- Hyun Ji Kim
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Boram Kim
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Hyung Jung Byun
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Lu Yu
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Tuan Minh Nguyen
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Thi Ha Nguyen
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Phuong Anh Do
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Eun Ji Kim
- Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455, USA;
| | - Kyung Ah Cheong
- Department of Dermatology, Dongguk University Ilsan Hospital, 814 Siksa-dong, Ilsandong-gu, Goyang-si 10326, Korea; (K.A.C.); (G.J.K.); (A.Y.L.)
| | - Kyung Sung Kim
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Hiệu Huy Phùng
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Mostafizur Rahman
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Ji Yun Jang
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
- National Cancer Center, Goyang 10408, Korea; (S.B.R.); (H.L.)
| | - Seung Bae Rho
- National Cancer Center, Goyang 10408, Korea; (S.B.R.); (H.L.)
| | - Gyeoung Jin Kang
- Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455, USA;
| | - Mi Kyung Park
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
- National Cancer Center, Goyang 10408, Korea; (S.B.R.); (H.L.)
| | - Ho Lee
- National Cancer Center, Goyang 10408, Korea; (S.B.R.); (H.L.)
| | - Kyeong Lee
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Jungsook Cho
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Hyo Kyung Han
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Sang Geon Kim
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
| | - Ai Young Lee
- Department of Dermatology, Dongguk University Ilsan Hospital, 814 Siksa-dong, Ilsandong-gu, Goyang-si 10326, Korea; (K.A.C.); (G.J.K.); (A.Y.L.)
| | - Chang Hoon Lee
- BK21 FOUR Team and Integrated Research Institute for Drug Development, College of Pharmacy, Dongguk University, Seoul 04620, Korea; (H.J.K.); (B.K.); (H.J.B.); (L.Y.); (T.M.N.); (T.H.N.); (P.A.D.); (K.S.K.); (H.H.P.); (M.R.); (J.Y.J.); (M.K.P.); (K.L.); (J.C.); (H.K.H.); (S.G.K.)
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4
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Correlation between an intronic SNP genotype and ARL15 level in rheumatoid arthritis. J Genet 2021. [DOI: 10.1007/s12041-021-01286-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Fujisawa S, Qiu H, Nozaki S, Chiba S, Katoh Y, Nakayama K. ARL3 and ARL13B GTPases participate in distinct steps of INPP5E targeting to the ciliary membrane. Biol Open 2021; 10:bio058843. [PMID: 34447983 PMCID: PMC8496693 DOI: 10.1242/bio.058843] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/19/2021] [Indexed: 01/02/2023] Open
Abstract
INPP5E, a phosphoinositide 5-phosphatase, localizes on the ciliary membrane via its C-terminal prenyl moiety, and maintains the distinct ciliary phosphoinositide composition. The ARL3 GTPase contributes to the ciliary membrane localization of INPP5E by stimulating the release of PDE6D bound to prenylated INPP5E. Another GTPase, ARL13B, which is localized on the ciliary membrane, contributes to the ciliary membrane retention of INPP5E by directly binding to its ciliary targeting sequence. However, as ARL13B was shown to act as a guanine nucleotide exchange factor (GEF) for ARL3, it is also possible that ARL13B indirectly mediates the ciliary INPP5E localization via activating ARL3. We here show that INPP5E is delocalized from cilia in both ARL3-knockout (KO) and ARL13B-KO cells. However, some of the abnormal phenotypes were different between these KO cells, while others were found to be common, indicating the parallel roles of ARL3 and ARL13B, at least concerning some cellular functions. For several variants of ARL13B, their ability to interact with INPP5E, rather than their ability as an ARL3-GEF, was associated with whether they could rescue the ciliary localization of INPP5E in ARL13B-KO cells. These observations together indicate that ARL13B determines the ciliary localization of INPP5E, mainly by its direct binding to INPP5E.
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Affiliation(s)
- Sayaka Fujisawa
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hantian Qiu
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shohei Nozaki
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shuhei Chiba
- Department of Genetic Disease Research, Graduate School of Medicine, Osaka City University, Abeno-ku, Osaka 545-8585, Japan
| | - Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Vargová R, Wideman JG, Derelle R, Klimeš V, Kahn RA, Dacks JB, Eliáš M. A Eukaryote-Wide Perspective on the Diversity and Evolution of the ARF GTPase Protein Family. Genome Biol Evol 2021; 13:6319025. [PMID: 34247240 PMCID: PMC8358228 DOI: 10.1093/gbe/evab157] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2021] [Indexed: 12/21/2022] Open
Abstract
The evolution of eukaryotic cellular complexity is interwoven with the extensive diversification of many protein families. One key family is the ARF GTPases that act in eukaryote-specific processes, including membrane traffic, tubulin assembly, actin dynamics, and cilia-related functions. Unfortunately, our understanding of the evolution of this family is limited. Sampling an extensive set of available genome and transcriptome sequences, we have assembled a data set of over 2,000 manually curated ARF family genes from 114 eukaryotic species, including many deeply diverged protist lineages, and carried out comprehensive molecular phylogenetic analyses. These reconstructed as many as 16 ARF family members present in the last eukaryotic common ancestor, nearly doubling the previously inferred ancient system complexity. Evidence for the wide occurrence and ancestral origin of Arf6, Arl13, and Arl16 is presented for the first time. Moreover, Arl17, Arl18, and SarB, newly described here, are absent from well-studied model organisms and as a result their function(s) remain unknown. Analyses of our data set revealed a previously unsuspected diversity of membrane association modes and domain architectures within the ARF family. We detail the step-wise expansion of the ARF family in the metazoan lineage, including discovery of several new animal-specific family members. Delving back to its earliest evolution in eukaryotes, the resolved relationship observed between the ARF family paralogs sets boundaries for scenarios of vesicle coat origins during eukaryogenesis. Altogether, our work fundamentally broadens the understanding of the diversity and evolution of a protein family underpinning the structural and functional complexity of the eukaryote cells.
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Affiliation(s)
- Romana Vargová
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Czech Republic
| | - Jeremy G Wideman
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Romain Derelle
- Station d'Ecologie Théorique et Expérimentale, UMR CNRS 5321, Moulis, France
| | - Vladimír Klimeš
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Czech Republic
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Joel B Dacks
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.,Centre for Life's Origin and Evolution, Department of Genetics, Evolution and Environment, University College of London, United Kingdom
| | - Marek Eliáš
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Czech Republic
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Wirth M, Mouilleron S, Zhang W, Sjøttem E, Princely Abudu Y, Jain A, Lauritz Olsvik H, Bruun JA, Razi M, Jefferies HB, Lee R, Joshi D, O'Reilly N, Johansen T, Tooze SA. Phosphorylation of the LIR Domain of SCOC Modulates ATG8 Binding Affinity and Specificity. J Mol Biol 2021; 433:166987. [DOI: https:/doi.org/10.1016/j.jmb.2021.166987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
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8
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Phosphorylation of the LIR Domain of SCOC Modulates ATG8 Binding Affinity and Specificity. J Mol Biol 2021; 433:166987. [PMID: 33845085 PMCID: PMC8202330 DOI: 10.1016/j.jmb.2021.166987] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/27/2021] [Accepted: 04/04/2021] [Indexed: 12/15/2022]
Abstract
Autophagy is a highly conserved degradative pathway, essential for cellular homeostasis and implicated in diseases including cancer and neurodegeneration. Autophagy-related 8 (ATG8) proteins play a central role in autophagosome formation and selective delivery of cytoplasmic cargo to lysosomes by recruiting autophagy adaptors and receptors. The LC3-interacting region (LIR) docking site (LDS) of ATG8 proteins binds to LIR motifs present in autophagy adaptors and receptors. LIR-ATG8 interactions can be highly selective for specific mammalian ATG8 family members (LC3A-C, GABARAP, and GABARAPL1-2) and how this specificity is generated and regulated is incompletely understood. We have identified a LIR motif in the Golgi protein SCOC (short coiled-coil protein) exhibiting strong binding to GABARAP, GABARAPL1, LC3A and LC3C. The residues within and surrounding the core LIR motif of the SCOC LIR domain were phosphorylated by autophagy-related kinases (ULK1-3, TBK1) increasing specifically LC3 family binding. More distant flanking residues also contributed to ATG8 binding. Loss of these residues was compensated by phosphorylation of serine residues immediately adjacent to the core LIR motif, indicating that the interactions of the flanking LIR regions with the LDS are important and highly dynamic. Our comprehensive structural, biophysical and biochemical analyses support and provide novel mechanistic insights into how phosphorylation of LIR domain residues regulates the affinity and binding specificity of ATG8 proteins towards autophagy adaptors and receptors.
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Feng H, Cheng H, Hsiao T, Lin T, Hsu J, Huang L, Yu C. ArfGAP1 acts as a GTPase‐activating protein for human ADP‐ribosylation factor‐like 1 protein. FASEB J 2021; 35:e21337. [DOI: 10.1096/fj.202000818rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 12/13/2020] [Accepted: 12/17/2020] [Indexed: 01/08/2023]
Affiliation(s)
- Hsiang‐Pu Feng
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Hsiao‐Yun Cheng
- Department of Cell and Molecular Biology, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Ting‐Feng Hsiao
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Tai‐Wei Lin
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Jia‐Wei Hsu
- Institute of Molecular Medicine, College of Medicine National Taiwan University Taipei Taiwan
- Institute of Biochemical Sciences, College of Life Science National Taiwan University Taipei Taiwan
| | - Lien‐Hung Huang
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
- Department of Neurosurgery Kaohsiung Chang Gung Memorial Hospital Kaohsiung Taiwan
| | - Chia‐Jung Yu
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
- Department of Cell and Molecular Biology, College of Medicine Chang Gung University Taoyuan Taiwan
- Department of Thoracic Medicine Chang Gung Memorial Hospital Taoyuan Taiwan
- Molecular Medicine Research Center Chang Gung University Taoyuan Taiwan
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The ADP-ribosylation factor-like small GTPase FgArl1 participates in growth, pathogenicity and DON production in Fusarium graminearum. Fungal Biol 2020; 124:969-980. [PMID: 33059848 DOI: 10.1016/j.funbio.2020.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 08/08/2020] [Accepted: 08/20/2020] [Indexed: 01/04/2023]
Abstract
Fusarium graminearum is the main pathogen of Fusarium head blight (FHB) in wheat and related species, which causes serious production decreases and economic losses and produces toxins such as deoxynivalenol (DON), which endangers the health of humans and livestock. Vesicle transport is a basic physiological process required for cell survival in eukaryotes. Many regulators of vesicle transport are reported to be involved in the pathogenicity of fungi. In yeast and mammalian cells, the ADP-ribosylation factor-like small GTPase Arl1 and its orthologs are involved in regulating vesicular trafficking, cytoskeletal reorganization and other significant biological processes. However, the role of Arl1 in F. graminearum is not well understood. In this study, we characterized the Arl1-homologous protein FgArl1 in F. graminearum and showed that FgArl1 is located in the trans-Golgi apparatus. The deletion of FgARL1 resulted in a significant decrease in vegetative growth and pathogenicity. Further analyses of the ΔFgarl1 mutant revealed defects in the production of DON. Taken together, these results indicate that FgArl1 is important in the development and pathogenicity of F. graminearum.
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11
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Fisher S, Kuna D, Caspary T, Kahn RA, Sztul E. ARF family GTPases with links to cilia. Am J Physiol Cell Physiol 2020; 319:C404-C418. [PMID: 32520609 PMCID: PMC7500214 DOI: 10.1152/ajpcell.00188.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The ADP-ribosylation factor (ARF) superfamily of regulatory GTPases, including both the ARF and ARF-like (ARL) proteins, control a multitude of cellular functions, including aspects of vesicular traffic, lipid metabolism, mitochondrial architecture, the assembly and dynamics of the microtubule and actin cytoskeletons, and other pathways in cell biology. Considering their general utility, it is perhaps not surprising that increasingly ARF/ARLs have been found in connection to primary cilia. Here, we critically evaluate the current knowledge of the roles four ARF/ARLs (ARF4, ARL3, ARL6, ARL13B) play in cilia and highlight key missing information that would help move our understanding forward. Importantly, these GTPases are themselves regulated by guanine nucleotide exchange factors (GEFs) that activate them and by GTPase-activating proteins (GAPs) that act as both effectors and terminators of signaling. We believe that the identification of the GEFs and GAPs and better models of the actions of these GTPases and their regulators will provide a much deeper understanding and appreciation of the mechanisms that underly ciliary functions and the causes of a number of human ciliopathies.
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Affiliation(s)
- Skylar Fisher
- 1Department of Biochemistry, Emory University
School of Medicine, Atlanta,
Georgia
| | - Damian Kuna
- 2Department of Cell, Developmental and Integrative
Biology, University of Alabama at Birmingham,
Birmingham, Alabama
| | - Tamara Caspary
- 3Department of Human Genetics, Emory
University School of Medicine, Atlanta,
Georgia
| | - Richard A. Kahn
- 1Department of Biochemistry, Emory University
School of Medicine, Atlanta,
Georgia
| | - Elizabeth Sztul
- 2Department of Cell, Developmental and Integrative
Biology, University of Alabama at Birmingham,
Birmingham, Alabama
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12
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Turn RE, East MP, Prekeris R, Kahn RA. The ARF GAP ELMOD2 acts with different GTPases to regulate centrosomal microtubule nucleation and cytokinesis. Mol Biol Cell 2020; 31:2070-2091. [PMID: 32614697 PMCID: PMC7543072 DOI: 10.1091/mbc.e20-01-0012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ELMOD2 is a ∼32 kDa protein first purified by its GTPase-activating protein (GAP) activity toward ARL2 and later shown to have uniquely broad specificity toward ARF family GTPases in in vitro assays. To begin the task of defining its functions in cells, we deleted ELMOD2 in immortalized mouse embryonic fibroblasts and discovered a number of cellular defects, which are reversed upon expression of ELMOD2-myc. We show that these defects, resulting from the loss of ELMOD2, are linked to two different pathways and two different GTPases: with ARL2 and TBCD to support microtubule nucleation from centrosomes and with ARF6 in cytokinesis. These data highlight key aspects of signaling by ARF family GAPs that contribute to previously underappreciated sources of complexity, including GAPs acting from multiple sites in cells, working with multiple GTPases, and contributing to the spatial and temporal control of regulatory GTPases by serving as both GAPs and effectors.
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Affiliation(s)
- Rachel E Turn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322.,Biochemistry, Cell & Developmental Biology Graduate Program, Laney Graduate School, Emory University, Atlanta, GA 30307
| | - Michael P East
- Department of Pharmacology, University of North Carolina Chapel Hill, Chapel Hill, NC 27599
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado, Aurora, CO 80045
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322
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13
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Gigante ED, Taylor MR, Ivanova AA, Kahn RA, Caspary T. ARL13B regulates Sonic hedgehog signaling from outside primary cilia. eLife 2020; 9:50434. [PMID: 32129762 PMCID: PMC7075693 DOI: 10.7554/elife.50434] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 02/25/2020] [Indexed: 01/13/2023] Open
Abstract
ARL13B is a regulatory GTPase highly enriched in cilia. Complete loss of Arl13b disrupts cilia architecture, protein trafficking and Sonic hedgehog signaling. To determine whether ARL13B is required within cilia, we knocked in a cilia-excluded variant of ARL13B (V358A) and showed it retains all known biochemical function. We found that ARL13BV358A protein was expressed but could not be detected in cilia, even when retrograde ciliary transport was blocked. We showed Arl13bV358A/V358A mice are viable and fertile with normal Shh signal transduction. However, in contrast to wild type cilia, Arl13bV358A/V358A cells displayed short cilia and lacked ciliary ARL3 and INPP5E. These data indicate that ARL13B's role within cilia can be uncoupled from its function outside of cilia. Furthermore, these data imply that the cilia defects upon complete absence of ARL13B do not underlie the alterations in Shh transduction, which is unexpected given the requirement of cilia for Shh transduction.
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Affiliation(s)
- Eduardo D Gigante
- Neuroscience Graduate Program, Emory University School of MedicineAtlantaUnited States,Department of Human Genetics, Emory University School of MedicineAtlantaUnited States
| | - Megan R Taylor
- Emory College of Arts and Sciences, Emory University School of MedicineAtlantaUnited States
| | - Anna A Ivanova
- Department of Biochemistry, Emory University School of MedicineAtlantaUnited States
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of MedicineAtlantaUnited States
| | - Tamara Caspary
- Department of Human Genetics, Emory University School of MedicineAtlantaUnited States
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14
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Zhang S, Yang L, Li L, Zhong K, Wang W, Liu M, Li Y, Liu X, Yu R, He J, Zhang H, Zheng X, Wang P, Zhang Z. System-Wide Characterization of MoArf GTPase Family Proteins and Adaptor Protein MoGga1 Involved in the Development and Pathogenicity of Magnaporthe oryzae. mBio 2019; 10:e02398-19. [PMID: 31615964 PMCID: PMC6794486 DOI: 10.1128/mbio.02398-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 09/17/2019] [Indexed: 12/18/2022] Open
Abstract
ADP ribosylation factor (Arf) small GTPase family members are involved in vesicle trafficking and organelle maintenance in organisms ranging from Saccharomyces cerevisiae to humans. A previous study identified Magnaporthe oryzae Arf6 (MoArf6) as one of the Arf proteins that regulates growth and conidiation in the rice blast fungus M. oryzae, but the remaining family proteins remain unknown. Here, we identified six additional Arf proteins, including MoArf1, MoArl1, MoArl3, MoArl8, MoCin4, and MoSar1, as well as their sole adaptor protein, MoGga1, and determined their shared and specific functions. We showed that the majority of these proteins exhibit positive regulatory functions, most notably, in growth. Importantly, MoArl1, MoCin4, and MoGga1 are involved in pathogenicity through the regulation of host penetration and invasive hyphal growth. MoArl1 and MoCin4 also regulate normal vesicle trafficking, and MoCin4 further controls the formation of the biotrophic interfacial complex (BIC). Moreover, we showed that Golgi-cytoplasm cycling of MoArl1 is required for its function. Finally, we demonstrated that interactions between MoArf1 and MoArl1 with MoGga1 are important for Golgi localization and pathogenicity. Collectively, our findings revealed the shared and specific functions of Arf family members in M. oryzae and shed light on how these proteins function through conserved mechanisms to govern growth, transport, and virulence of the blast fungus.IMPORTANCEMagnaporthe oryzae is the causal agent of rice blast, representing the most devastating diseases of rice worldwide, which results in losses of amounts of rice that could feed more than 60 million people each year. Arf (ADP ribosylation factor) small GTPase family proteins are involved in vesicle trafficking and organelle maintenance in eukaryotic cells. To investigate the function of Arf family proteins in M. oryzae, we systematically characterized all seven Arf proteins and found that they have shared and specific functions in governing the growth, development, and pathogenicity of the blast fungus. We have also identified the pathogenicity-related protein MoGga1 as the common adaptor of MoArf1 and MoArl1. Our findings are important because they provide the first comprehensive characterization of the Arf GTPase family proteins and their adaptor protein MoGga1 functioning in a plant-pathogenic fungus, which could help to reveal new fungicide targets to control this devastating disease.
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Affiliation(s)
- Shengpei Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Lina Yang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Lianwei Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Kaili Zhong
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Wenhao Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Muxing Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ying Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Rui Yu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jialiang He
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ping Wang
- Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
- Department of Microbiology, Immunology & Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
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15
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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: 149] [Impact Index Per Article: 29.8] [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.
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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
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16
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Abstract
The Golgi apparatus is a central intracellular membrane-bound organelle with key functions in trafficking, processing, and sorting of newly synthesized membrane and secretory proteins and lipids. To best perform these functions, Golgi membranes form a unique stacked structure. The Golgi structure is dynamic but tightly regulated; it undergoes rapid disassembly and reassembly during the cell cycle of mammalian cells and is disrupted under certain stress and pathological conditions. In the past decade, significant amount of effort has been made to reveal the molecular mechanisms that regulate the Golgi membrane architecture and function. Here we review the major discoveries in the mechanisms of Golgi structure formation, regulation, and alteration in relation to its functions in physiological and pathological conditions to further our understanding of Golgi structure and function in health and diseases.
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Affiliation(s)
- Jie Li
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Erpan Ahat
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
- Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, USA.
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17
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Kösling SK, Fansa EK, Maffini S, Wittinghofer A. Mechanism and dynamics of INPP5E transport into and inside the ciliary compartment. Biol Chem 2018; 399:277-292. [PMID: 29140789 DOI: 10.1515/hsz-2017-0226] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/03/2017] [Indexed: 11/15/2022]
Abstract
The inositol polyphosphate 5'-phosphatase E (INPP5E) localizes to cilia. We showed that the carrier protein phosphodiesterase 6 delta subunit (PDE6δ) mediates the sorting of farnesylated INPP5E into cilia due to high affinity binding and release by the ADP-ribosylation factor (Arf)-like protein Arl3·GTP. However, the dynamics of INPP5E transport into and inside the ciliary compartment are not fully understood. Here, we investigate the movement of INPP5E using live cell fluorescence microscopy and fluorescence recovery after photobleaching (FRAP) analysis. We show that PDE6δ and the dynein transport system are essential for ciliary sorting and entry of INPP5E. However, its innerciliary transport is regulated solely by the intraflagellar transport (IFT) system, independent from PDE6δ activity and INPP5E farnesylation. By contrast, movement of Arl3 into and within cilia occurs freely by diffusion and IFT-independently. The farnesylation defective INPP5E CaaX box mutant loses the exclusive ciliary localization. The accumulation of this mutant at centrioles after photobleaching suggests an affinity trap mechanism for ciliary entry, that in case of the wild type is overcome by the interaction with PDE6δ. Collectively, we postulate a three-step mechanism regulating ciliary localization of INPP5E, consisting of farnesylation- and PDE6δ-mediated targeting, INPP5E-PDE6δ complex diffusion into the cilium with transfer to the IFT system, and retention inside cilia.
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Affiliation(s)
- Stefanie Kristine Kösling
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, D-44227 Dortmund, Germany
| | - Eyad Kalawy Fansa
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, D-44227 Dortmund, Germany
| | - Stefano Maffini
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, D-44227 Dortmund, Germany
| | - Alfred Wittinghofer
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, D-44227 Dortmund, Germany
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18
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Schiavon CR, Griffin ME, Pirozzi M, Parashuraman R, Zhou W, Jinnah HA, Reines D, Kahn RA. Compositional complexity of rods and rings. Mol Biol Cell 2018; 29:2303-2316. [PMID: 30024290 PMCID: PMC6249804 DOI: 10.1091/mbc.e18-05-0274] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rods and rings (RRs) are large linear- or circular-shaped structures typically described as polymers of IMPDH (inosine monophosphate dehydrogenase). They have been observed across a wide variety of cell types and species and can be induced to form by inhibitors of IMPDH. RRs are thought to play a role in the regulation of de novo guanine nucleotide synthesis; however, the function and regulation of RRs is poorly understood. Here we show that the regulatory GTPase, ARL2, a subset of its binding partners, and several resident proteins at the endoplasmic reticulum (ER) also localize to RRs. We also have identified two new inducers of RR formation: AICAR and glucose deprivation. We demonstrate that RRs can be disassembled if guanine nucleotides can be generated by salvage synthesis regardless of the inducer. Finally, we show that there is an ordered addition of components as RRs mature, with IMPDH first forming aggregates, followed by ARL2, and only later calnexin, a marker of the ER. These findings suggest that RRs are considerably more complex than previously thought and that the function(s) of RRs may include involvement of a regulatory GTPase, its effectors, and potentially contacts with intracellular membranes.
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Affiliation(s)
- Cara R Schiavon
- Cancer Biology Graduate Program, Graduate Division of Biomedical and Biological Sciences, Laney Graduate School, Atlanta, GA 30307
| | - Maxwell E Griffin
- Cancer Biology Graduate Program, Graduate Division of Biomedical and Biological Sciences, Laney Graduate School, Atlanta, GA 30307
| | - Marinella Pirozzi
- EuroBioImaging Facility, Institute of Protein Biochemistry, 80131 Naples, Italy
| | - Raman Parashuraman
- EuroBioImaging Facility, Institute of Protein Biochemistry, 80131 Naples, Italy
| | - Wei Zhou
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322
| | - H A Jinnah
- Department of Neurology and Human Genetics, Emory University School of Medicine, Atlanta, GA 30322
| | - Daniel Reines
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322
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19
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Barlow LD, Nývltová E, Aguilar M, Tachezy J, Dacks JB. A sophisticated, differentiated Golgi in the ancestor of eukaryotes. BMC Biol 2018; 16:27. [PMID: 29510703 PMCID: PMC5840792 DOI: 10.1186/s12915-018-0492-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/25/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Golgi apparatus is a central meeting point for the endocytic and exocytic systems in eukaryotic cells, and the organelle's dysfunction results in human disease. Its characteristic morphology of multiple differentiated compartments organized into stacked flattened cisternae is one of the most recognizable features of modern eukaryotic cells, and yet how this is maintained is not well understood. The Golgi is also an ancient aspect of eukaryotes, but the extent and nature of its complexity in the ancestor of eukaryotes is unclear. Various proteins have roles in organizing the Golgi, chief among them being the golgins. RESULTS We address Golgi evolution by analyzing genome sequences from organisms which have lost stacked cisternae as a feature of their Golgi and those that have not. Using genomics and immunomicroscopy, we first identify Golgi in the anaerobic amoeba Mastigamoeba balamuthi. We then searched 87 genomes spanning eukaryotic diversity for presence of the most prominent proteins implicated in Golgi structure, focusing on golgins. We show some candidates as animal specific and others as ancestral to eukaryotes. CONCLUSIONS None of the proteins examined show a phyletic distribution that correlates with the morphology of stacked cisternae, suggesting the possibility of stacking as an emergent property. Strikingly, however, the combination of golgins conserved among diverse eukaryotes allows for the most detailed reconstruction of the organelle to date, showing a sophisticated Golgi with differentiated compartments and trafficking pathways in the common eukaryotic ancestor.
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Affiliation(s)
- Lael D Barlow
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 5-31 Medical Sciences Building, Edmonton, Alberta, T6G 2H7, Canada
| | - Eva Nývltová
- Department of Parasitology (BIOCEV), Faculty of Science, Charles University, Průmyslová 595, 252 42, Vestec, Czech Republic.,Department of Neurology, University of Miami Miller School of Medicine, 1600 NW 10th Avenue, Rosenstiel Medical Science Building (RMSB) # 2067, Miami, Florida, 33136, USA
| | - Maria Aguilar
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 5-31 Medical Sciences Building, Edmonton, Alberta, T6G 2H7, Canada
| | - Jan Tachezy
- Department of Parasitology (BIOCEV), Faculty of Science, Charles University, Průmyslová 595, 252 42, Vestec, Czech Republic
| | - Joel B Dacks
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, 5-31 Medical Sciences Building, Edmonton, Alberta, T6G 2H7, Canada. .,Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
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20
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Jean F, Pilgrim D. Coordinating the uncoordinated: UNC119 trafficking in cilia. Eur J Cell Biol 2017; 96:643-652. [PMID: 28935136 DOI: 10.1016/j.ejcb.2017.09.001] [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] [Received: 07/18/2017] [Revised: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 12/29/2022] Open
Abstract
Constructing the distinct subcellular environment of the cilium relies in a large part upon intraflagellar transport (IFT) proteins, which traffic cargo both to and within the cilium. However, evidence from the last 10 years suggests that IFT alone is not sufficient to generate the ciliary environment. One essential factor is UNC119, which interacts with known IFT molecular switches to transport ciliary cargos. Despite its apparent importance in ciliary trafficking though, human UNC119 mutations have only rarely been associated with diseases commonly linked with ciliopathies. This review will outline the trafficking pathways required for constructing the cilium by highlighting UNC119's role and the complexities involved in ciliary trafficking. Finally, despite important roles for UNC119 in cilia, UNC119 proteins also interact with non-ciliary proteins to affect other cellular processes.
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21
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Ivanova AA, Caspary T, Seyfried NT, Duong DM, West AB, Liu Z, Kahn RA. Biochemical characterization of purified mammalian ARL13B protein indicates that it is an atypical GTPase and ARL3 guanine nucleotide exchange factor (GEF). J Biol Chem 2017; 292:11091-11108. [PMID: 28487361 PMCID: PMC5491791 DOI: 10.1074/jbc.m117.784025] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 05/02/2017] [Indexed: 12/11/2022] Open
Abstract
Primary cilia play central roles in signaling during metazoan development. Several key regulators of ciliogenesis and ciliary signaling are mutated in humans, resulting in a number of ciliopathies, including Joubert syndrome (JS). ARL13B is a ciliary GTPase with at least three missense mutations identified in JS patients. ARL13B is a member of the ADP ribosylation factor family of regulatory GTPases, but is atypical in having a non-homologous, C-terminal domain of ∼20 kDa and at least one key residue difference in the consensus GTP-binding motifs. For these reasons, and to establish a solid biochemical basis on which to begin to model its actions in cells and animals, we developed preparations of purified, recombinant, murine Arl13b protein. We report results from assays for solution-based nucleotide binding, intrinsic and GTPase-activating protein-stimulated GTPase, and ARL3 guanine nucleotide exchange factor activities. Biochemical analyses of three human missense mutations found in JS and of two consensus GTPase motifs reinforce the atypical properties of this regulatory GTPase. We also discovered that murine Arl13b is a substrate for casein kinase 2, a contaminant in our preparation from human embryonic kidney cells. This activity, and the ability of casein kinase 2 to use GTP as a phosphate donor, may be a source of differences between our data and previously published results. These results provide a solid framework for further research into ARL13B on which to develop models for the actions of this clinically important cell regulator.
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Affiliation(s)
| | - Tamara Caspary
- Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322 and
| | | | | | - Andrew B West
- the Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Zhiyong Liu
- the Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, Alabama 35294
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22
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Newman LE, Schiavon CR, Turn RE, Kahn RA. The ARL2 GTPase regulates mitochondrial fusion from the intermembrane space. CELLULAR LOGISTICS 2017; 7:e1340104. [PMID: 28944094 PMCID: PMC5602422 DOI: 10.1080/21592799.2017.1340104] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/05/2017] [Indexed: 01/11/2023]
Abstract
Mitochondria are essential, dynamic organelles that regularly undergo both fusion and fission in response to cellular conditions, though mechanisms of the regulation of their dynamics are incompletely understood. We provide evidence that increased activity of the small GTPase ARL2 is strongly correlated with an increase in fusion, while loss of ARL2 activity results in a decreased rate of mitochondrial fusion. Strikingly, expression of activated ARL2 can partially restore the loss of fusion resulting from deletion of either mitofusin 1 (MFN1) or mitofusin 2 (MFN2), but not deletion of both. We only observe the full effects of ARL2 on mitochondrial fusion when it is present in the intermembrane space (IMS), as constructs driven to the matrix or prevented from entering mitochondria are essentially inactive in promoting fusion. Thus, ARL2 is the first regulatory (small) GTPase shown to act inside mitochondria or in the fusion pathway. Finally, using high-resolution, structured illumination microscopy (SIM), we find that ARL2 and mitofusin immunoreactivities present as punctate staining along mitochondria that share a spatial convergence in fluorescence signals. Thus, we propose that ARL2 plays a regulatory role in mitochondrial fusion, acting from the IMS and requiring at least one of the mitofusins in their canonical role in fusion of the outer membranes.
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Affiliation(s)
- Laura E. Newman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Cara R. Schiavon
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Rachel E. Turn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
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Abstract
ADP-ribosylation factors (Arfs) and ADP-ribosylation factor-like proteins (Arls) are highly conserved small GTPases that function as main regulators of vesicular trafficking and cytoskeletal reorganization. Arl1, the first identified member of the large Arl family, is an important regulator of Golgi complex structure and function in organisms ranging from yeast to mammals. Together with its effectors, Arl1 has been shown to be involved in several cellular processes, including endosomal trans-Golgi network and secretory trafficking, lipid droplet and salivary granule formation, innate immunity and neuronal development, stress tolerance, as well as the response of the unfolded protein. In this Commentary, we provide a comprehensive summary of the Arl1-dependent cellular functions and a detailed characterization of several Arl1 effectors. We propose that involvement of Arl1 in these diverse cellular functions reflects the fact that Arl1 is activated at several late-Golgi sites, corresponding to specific molecular complexes that respond to and integrate multiple signals. We also provide insight into how the GTP-GDP cycle of Arl1 is regulated, and highlight a newly discovered mechanism that controls the sophisticated regulation of Arl1 activity at the Golgi complex.
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Affiliation(s)
- Chia-Jung Yu
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Linkou, Tao-Yuan 33302, Taiwan.,Department of Thoracic Medicine, Chang Gung Memorial Hospital, Linkou, Tao-Yuan 33305, Taiwan
| | - Fang-Jen S Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan .,Department of Medical Research, National Taiwan University Hospital, Taipei 10002, Taiwan
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24
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Nozaki S, Katoh Y, Terada M, Michisaka S, Funabashi T, Takahashi S, Kontani K, Nakayama K. Regulation of ciliary retrograde protein trafficking by the Joubert syndrome proteins ARL13B and INPP5E. J Cell Sci 2017; 130:563-576. [PMID: 27927754 DOI: 10.1242/jcs.197004] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/29/2016] [Indexed: 12/17/2022] Open
Abstract
ARL13B (a small GTPase) and INPP5E (a phosphoinositide 5-phosphatase) are ciliary proteins encoded by causative genes of Joubert syndrome. We here showed, by taking advantage of a visible immunoprecipitation assay, that ARL13B interacts with the IFT46 -: IFT56 (IFT56 is also known as TTC26) dimer of the intraflagellar transport (IFT)-B complex, which mediates anterograde ciliary protein trafficking. However, the ciliary localization of ARL13B was found to be independent of its interaction with IFT-B, but dependent on the ciliary-targeting sequence RVEP in its C-terminal region. ARL13B-knockout cells had shorter cilia than control cells and exhibited aberrant localization of ciliary proteins, including INPP5E. In particular, in ARL13B-knockout cells, the IFT-A and IFT-B complexes accumulated at ciliary tips, and GPR161 (a negative regulator of Hedgehog signaling) could not exit cilia in response to stimulation with Smoothened agonist. This abnormal phenotype was rescued by the exogenous expression of wild-type ARL13B, as well as by its mutant defective in the interaction with IFT-B, but not by its mutants defective in INPP5E binding or in ciliary localization. Thus, ARL13B regulates IFT-A-mediated retrograde protein trafficking within cilia through its interaction with INPP5E.
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Affiliation(s)
- Shohei Nozaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masaya Terada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Saki Michisaka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Teruki Funabashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Senye Takahashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kenji Kontani
- Department of Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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25
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Francis JW, Turn RE, Newman LE, Schiavon C, Kahn RA. Higher order signaling: ARL2 as regulator of both mitochondrial fusion and microtubule dynamics allows integration of 2 essential cell functions. Small GTPases 2016; 7:188-196. [PMID: 27400436 PMCID: PMC5129891 DOI: 10.1080/21541248.2016.1211069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 10/21/2022] Open
Abstract
ARL2 is among the most highly conserved proteins, predicted to be present in the last eukaryotic common ancestor, and ubiquitously expressed. Genetic screens in multiple model organisms identified ARL2, and its cytosolic binding partner cofactor D (TBCD), as important in tubulin folding and microtubule dynamics. Both ARL2 and TBCD also localize to centrosomes, making it difficult to dissect these effects. A growing body of evidence also has found roles for ARL2 inside mitochondria, as a regulator of mitochondrial fusion. Other studies have revealed roles for ARL2, in concert with its closest paralog ARL3, in the traffic of farnesylated cargos between membranes and specifically to cilia and photoreceptor cells. Details of each of these signaling processes continue to emerge. We summarize those data here and speculate about the potential for cross-talk or coordination of cell regulation, termed higher order signaling, based upon the use of a common GTPase in disparate cell functions.
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Affiliation(s)
- Joshua W. Francis
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Rachel E. Turn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Laura E. Newman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Cara Schiavon
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
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26
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Mariani LE, Bijlsma MF, Ivanova AA, Suciu SK, Kahn RA, Caspary T. Arl13b regulates Shh signaling from both inside and outside the cilium. Mol Biol Cell 2016; 27:mbc.E16-03-0189. [PMID: 27682584 PMCID: PMC5170560 DOI: 10.1091/mbc.e16-03-0189] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 08/16/2016] [Accepted: 09/20/2016] [Indexed: 12/21/2022] Open
Abstract
The regulatory GTPase Arl13b localizes to primary cilia, where it regulates Sonic hedgehog (Shh) signaling. Missense mutations in ARL13B can cause the ciliopathy Joubert syndrome, while the mouse null allele is embryonic lethal. We used mouse embryonic fibroblasts as a system to determine the effects of Arl13b mutations on Shh signaling. We tested a total of seven different mutants, three JS-causing variants, two point mutants predicted to alter guanine nucleotide handling, one that disrupts cilia localization, and one that prevents palmitoylation and thus membrane binding, in assays of transcriptional and non-transcriptional Shh signaling. We found that mutations disrupting Arl13b's palmitoylation site, cilia localization signal, or GTPase handling altered the Shh response in distinct assays of transcriptional or non-transcriptional signaling. In contrast, JS-causing mutations in Arl13b did not affect Shh signaling in these same assays, suggesting these mutations result in more subtle defects, likely affecting only a subset of signaling outputs. Finally, we show that restricting Arl13b from cilia interferes with its ability to regulate Shh-stimulated chemotaxis, despite previous evidence that cilia themselves are not required for this non-transcriptional Shh response. This points to a more complex relationship between the ciliary and non-ciliary roles of this regulatory GTPase than previously envisioned.
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Affiliation(s)
- Laura E Mariani
- *Department of Human Genetics, Emory University, Atlanta, GA, USA Neuroscience Graduate Program, Emory University, Atlanta, GA, USA
| | - Maarten F Bijlsma
- Laboratory for Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Academic Medical Center and Cancer Center Amsterdam, Amsterdam, The Netherlands
| | - Anna A Ivanova
- Department of Biochemistry, Emory University, Atlanta, GA, USA
| | - Sarah K Suciu
- *Department of Human Genetics, Emory University, Atlanta, GA, USA Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA, USA
| | - Richard A Kahn
- Department of Biochemistry, Emory University, Atlanta, GA, USA
| | - Tamara Caspary
- *Department of Human Genetics, Emory University, Atlanta, GA, USA
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27
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Cheung PYP, Pfeffer SR. Transport Vesicle Tethering at the Trans Golgi Network: Coiled Coil Proteins in Action. Front Cell Dev Biol 2016; 4:18. [PMID: 27014693 PMCID: PMC4791371 DOI: 10.3389/fcell.2016.00018] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 02/29/2016] [Indexed: 12/14/2022] Open
Abstract
The Golgi complex is decorated with so-called Golgin proteins that share a common feature: a large proportion of their amino acid sequences are predicted to form coiled-coil structures. The possible presence of extensive coiled coils implies that these proteins are highly elongated molecules that can extend a significant distance from the Golgi surface. This property would help them to capture or trap inbound transport vesicles and to tether Golgi mini-stacks together. This review will summarize our current understanding of coiled coil tethers that are needed for the receipt of transport vesicles at the trans Golgi network (TGN). How do long tethering proteins actually catch vesicles? Golgi-associated, coiled coil tethers contain numerous binding sites for small GTPases, SNARE proteins, and vesicle coat proteins. How are these interactions coordinated and are any or all of them important for the tethering process? Progress toward understanding these questions and remaining, unresolved mysteries will be discussed.
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Affiliation(s)
- Pak-Yan P Cheung
- Department of Biochemistry, Stanford University School of Medicine Stanford, CA, USA
| | - Suzanne R Pfeffer
- Department of Biochemistry, Stanford University School of Medicine Stanford, CA, USA
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28
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Gotthardt K, Lokaj M, Koerner C, Falk N, Gießl A, Wittinghofer A. A G-protein activation cascade from Arl13B to Arl3 and implications for ciliary targeting of lipidated proteins. eLife 2015; 4. [PMID: 26551564 PMCID: PMC4868535 DOI: 10.7554/elife.11859] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/06/2015] [Indexed: 12/11/2022] Open
Abstract
Small G-proteins of the ADP-ribosylation-factor-like (Arl) subfamily have been shown to be crucial to ciliogenesis and cilia maintenance. Active Arl3 is involved in targeting and releasing lipidated cargo proteins from their carriers PDE6δ and UNC119a/b to the cilium. However, the guanine nucleotide exchange factor (GEF) which activates Arl3 is unknown. Here we show that the ciliary G-protein Arl13B mutated in Joubert syndrome is the GEF for Arl3, and its function is conserved in evolution. The GEF activity of Arl13B is mediated by the G-domain plus an additional C-terminal helix. The switch regions of Arl13B are involved in the interaction with Arl3. Overexpression of Arl13B in mammalian cell lines leads to an increased Arl3·GTP level, whereas Arl13B Joubert-Syndrome patient mutations impair GEF activity and thus Arl3 activation. We anticipate that through Arl13B's exclusive ciliary localization, Arl3 activation is spatially restricted and thereby an Arl3·GTP compartment generated where ciliary cargo is specifically released.
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Affiliation(s)
- Katja Gotthardt
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Mandy Lokaj
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Carolin Koerner
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Nathalie Falk
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Andreas Gießl
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Alfred Wittinghofer
- Structural Biology Group, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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29
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Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
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Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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30
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Huang LH, Lee WC, You ST, Cheng CC, Yu CJ. Arfaptin-1 negatively regulates Arl1-mediated retrograde transport. PLoS One 2015; 10:e0118743. [PMID: 25789876 PMCID: PMC4366199 DOI: 10.1371/journal.pone.0118743] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 01/11/2015] [Indexed: 12/24/2022] Open
Abstract
The small GTPase Arf-like protein 1 (Arl1) is well known for its role in intracellular vesicular transport at the trans-Golgi network (TGN). In this study, we used differential affinity chromatography combined with mass spectrometry to identify Arf-interacting protein 1b (arfaptin-1b) as an Arl1-interacting protein and characterized a novel function for arfaptin-1 (including the arfaptin-1a and 1b isoforms) in Arl1-mediated retrograde transport. Using a Shiga-toxin subunit B (STxB) transportation assay, we demonstrated that knockdown of arfaptin-1 accelerated the retrograde transport of STxB from the endosome to the Golgi apparatus, whereas Arl1 knockdown inhibited STxB transport compared with control cells. Arfaptin-1 overexpression, but not an Arl1 binding-defective mutant (arfaptin-1b-F317A), consistently inhibited STxB transport. Exogenous arfaptin-1 expression did not interfere with the localization of the Arl1-interacting proteins golgin-97 and golgin-245 to the TGN and vice versa. Moreover, we found that the N-terminal region of arfaptin-1 was involved in the regulation of retrograde transport. Our results show that arfaptin-1 acts as a negative regulator in Arl1-mediated retrograde transport and suggest that different functional complexes containing Arl1 form in distinct microdomains and are responsible for different functions.
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Affiliation(s)
- Lien-Hung Huang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Wei-Chung Lee
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Shu-Ting You
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Chen Cheng
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Chia-Jung Yu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan
- * E-mail:
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31
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Bennett MA, Shern JF, Kahn RA. Reverse two-hybrid techniques in the yeast Saccharomyces cerevisiae. Methods Mol Biol 2015; 1278:433-446. [PMID: 25859967 DOI: 10.1007/978-1-4939-2425-7_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Use of the yeast two-hybrid system has provided definition to many previously uncharacterized pathways through the identification and characterization of novel protein-protein interactions. The two-hybrid system uses the bifunctional nature of transcription factors, such as the yeast enhancer Gal4, to allow protein-protein interactions to be monitored through changes in transcription of reporter genes. Once a positive interaction has been identified, either of the interacting proteins can be mutated by site-specific or randomly introduced changes, to produce proteins with a decreased ability to interact. Mutants generated using this strategy are very powerful reagents in tests of the biological significance of the interaction and in defining the residues involved in the interaction. Such techniques are termed reverse two-hybrid methods. We describe a reverse two-hybrid method that generates loss-of-interaction mutations of the catalytic subunit of the Escherichia coli heat-labile toxin (LTA1) with decreased binding to the active (GTP-bound) form of human ARF3, its protein cofactor. While newer methods are emerging for performing interaction screens in mammalian cells, instead of yeast, the use of reverse two-hybrid in yeast remains a robust and powerful means of identifying loss-of-interaction point mutants and compensating changes that remain among the most powerful tools of testing the biological significance of a protein-protein interaction.
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Affiliation(s)
- Matthew A Bennett
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd., Atlanta, GA, 30322-3050, USA
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32
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Ciliary membrane proteins traffic through the Golgi via a Rabep1/GGA1/Arl3-dependent mechanism. Nat Commun 2014; 5:5482. [PMID: 25405894 PMCID: PMC4237283 DOI: 10.1038/ncomms6482] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 10/06/2014] [Indexed: 01/14/2023] Open
Abstract
Primary cilia contain specific receptors and channel proteins that sense the extracellular milieu. Defective ciliary function causes ciliopathies such as autosomal dominant polycystic kidney disease (ADPKD). However, little is known about how large ciliary transmembrane proteins traffic to the cilia. Polycystin-1 (PC1) and -2 (PC2), the two ADPKD gene products, are large transmembrane proteins that co-localize to cilia where they act to control proper tubular diameter. Here we describe that PC1 and PC2 must interact and form a complex to reach the trans-Golgi network (TGN) for subsequent ciliary targeting. PC1 must also be proteolytically cleaved at a GPS site for this to occur. Using yeast two-hybrid screening coupled with a candidate approach, we identify a Rabep1/GGA1/Arl3-dependent ciliary targeting mechanism, whereby Rabep1 couples the polycystin complex to a GGA1/Arl3-based ciliary trafficking module at the TGN. This study provides novel insights into the ciliary trafficking mechanism of membrane proteins.
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33
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Newman LE, Zhou CJ, Mudigonda S, Mattheyses AL, Paradies E, Marobbio CMT, Kahn RA. The ARL2 GTPase is required for mitochondrial morphology, motility, and maintenance of ATP levels. PLoS One 2014; 9:e99270. [PMID: 24911211 PMCID: PMC4050054 DOI: 10.1371/journal.pone.0099270] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/13/2014] [Indexed: 02/06/2023] Open
Abstract
ARF-like 2 (ARL2) is a member of the ARF family and RAS superfamily of regulatory GTPases, predicted to be present in the last eukaryotic common ancestor, and essential in a number of model genetic systems. Though best studied as a regulator of tubulin folding, we previously demonstrated that ARL2 partially localizes to mitochondria. Here, we show that ARL2 is essential to a number of mitochondrial functions, including mitochondrial morphology, motility, and maintenance of ATP levels. We compare phenotypes resulting from ARL2 depletion and expression of dominant negative mutants and use these to demonstrate that the mitochondrial roles of ARL2 are distinct from its roles in tubulin folding. Testing of current models for ARL2 actions at mitochondria failed to support them. Rather, we found that knockdown of the ARL2 GTPase activating protein (GAP) ELMOD2 phenocopies two of three phenotypes of ARL2 siRNA, making it a likely effector for these actions. These results add new layers of complexity to ARL2 signaling, highlighting the need to deconvolve these different cell functions. We hypothesize that ARL2 plays essential roles inside mitochondria along with other cellular functions, at least in part to provide coupling of regulation between these essential cell processes.
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Affiliation(s)
- Laura E. Newman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Cheng-jing Zhou
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Samatha Mudigonda
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Alexa L. Mattheyses
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Eleonora Paradies
- Consiglio Nazionale delle Ricerche Institute of Biomembranes and Bioenergetics, Bari, Italy
| | | | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, United States of America
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34
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Ivanova AA, East MP, Yi SL, Kahn RA. Characterization of recombinant ELMOD (cell engulfment and motility domain) proteins as GTPase-activating proteins (GAPs) for ARF family GTPases. J Biol Chem 2014; 289:11111-11121. [PMID: 24616099 PMCID: PMC4036250 DOI: 10.1074/jbc.m114.548529] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/05/2014] [Indexed: 11/06/2022] Open
Abstract
The ARF family of regulatory GTPases, within the RAS superfamily, is composed of ~30 members in mammals, including up to six ARF and at least 18 ARF-like (ARL) proteins. They exhibit significant structural and biochemical conservation and regulate a variety of essential cellular processes, including membrane traffic, cell division, and energy metabolism; each with links to human diseases. We previously identified members of the ELMOD family as GTPase-activating proteins (GAPs) for ARL2 that displayed crossover activity for ARFs as well. To further characterize the GAP activities of the three human ELMODs as GAPs we developed new preparations of each after overexpression in human embryonic kidney (HEK293T) cells. This allowed much higher specific activities and enhanced stability and solubility of the purified proteins. The specificities of ELMOD1-3 as GAPs for six different members of the ARF family were determined and found to display wide variations, which we believe will reveal differences in cellular functions of family members. The non-opioid sigma-1 receptor (S1R) was identified as a novel effector of GAP activity of ELMOD1-3 proteins as its direct binding to either ELMOD1 or ELMOD2 resulted in loss of GAP activity. These findings are critical to understand the roles of ELMOD proteins in cell signaling in general and in the inner ear specifically, and open the door to exploration of the regulation of their GAP activities via agonists or antagonists of the S1R.
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Affiliation(s)
- Anna A Ivanova
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Michael P East
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Slee L Yi
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322.
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35
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Torres IL, Rosa-Ferreira C, Munro S. The Arf family G protein Arl1 is required for secretory granule biogenesis in Drosophila. J Cell Sci 2014; 127:2151-60. [PMID: 24610947 DOI: 10.1242/jcs.122028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The small G protein Arf like 1 (Arl1) is found at the Golgi complex, and its GTP-bound form recruits several effectors to the Golgi including GRIP-domain-containing coiled-coil proteins, and the Arf1 exchange factors Big1 and Big2. To investigate the role of Arl1, we have characterised a loss-of-function mutant of the Drosophila Arl1 orthologue. The gene is essential, and examination of clones of cells lacking Arl1 shows that it is required for recruitment of three of the four GRIP domain golgins to the Golgi, with Drosophila GCC185 being less dependent on Arl1. At a functional level, Arl1 is essential for formation of secretory granules in the larval salivary gland. When Arl1 is missing, Golgi are still present but there is a dispersal of adaptor protein 1 (AP-1), a clathrin adaptor that requires Arf1 for its membrane recruitment and which is known to be required for secretory granule biogenesis. Arl1 does not appear to be required for AP-1 recruitment in all tissues, suggesting that it is crucially required to enhance Arf1 activation at the trans-Golgi in particular tissues.
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Affiliation(s)
- Isabel L Torres
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | | | - Sean Munro
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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36
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Abstract
The ARF-like (ARL) proteins, within the ARF family, are a collection of functionally diverse GTPases that share extensive (>40 %) identity with the ARFs and each other and are assumed to share basic mechanisms of regulation and a very incompletely documented degree of overlapping regulators. At least four ARLs were already present in the last eukaryotic common ancestor, along with one ARF, and these have been expanded to >20 members in mammals. We know little about the majority of these proteins so our review will focus on those about which the most is known, including ARL1, ARL2, ARL3, ARL4s, ARL6, ARL13s, and ARFRP1. From this fragmentary information we extract some generalizations and conclusions regarding the sources and extent of specificity and functions of the ARLs.
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Affiliation(s)
- Alfred Wittinghofer
- Max-Planck-Institute of Molecular Physiology, Dortmund, Nordrhein-Westfalen Germany
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37
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Behrens C, Binotti B, Schmidt C, Robinson CV, Chua JJE, Kühnel K. Crystal structure of the human short coiled coil protein and insights into SCOC-FEZ1 complex formation. PLoS One 2013; 8:e76355. [PMID: 24098481 PMCID: PMC3788124 DOI: 10.1371/journal.pone.0076355] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 08/23/2013] [Indexed: 01/18/2023] Open
Abstract
The short coiled coil protein (SCOC) forms a complex with fasciculation and elongation protein zeta 1 (FEZ1). This complex is involved in autophagy regulation. We determined the crystal structure of the coiled coil domain of human SCOC at 2.7 Å resolution. SCOC forms a parallel left handed coiled coil dimer. We observed two distinct dimers in the crystal structure, which shows that SCOC is conformationally flexible. This plasticity is due to the high incidence of polar and charged residues at the core a/d-heptad positions. We prepared two double mutants, where these core residues were mutated to either leucines or valines (E93V/K97L and N125L/N132V). These mutations led to a dramatic increase in stability and change of oligomerisation state. The oligomerisation state of the mutants was characterized by multi-angle laser light scattering and native mass spectrometry measurements. The E93V/K97 mutant forms a trimer and the N125L/N132V mutant is a tetramer. We further demonstrate that SCOC forms a stable homogeneous complex with the coiled coil domain of FEZ1. SCOC dimerization and the SCOC surface residue R117 are important for this interaction.
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Affiliation(s)
- Caroline Behrens
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Beyenech Binotti
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Carla Schmidt
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom
| | - Carol V. Robinson
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom
| | - John Jia En Chua
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Karin Kühnel
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- * E-mail:
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Lefebvre M, Tetaud E, Thonnus M, Salin B, Boissier F, Blancard C, Sauvanet C, Metzler C, Espiau B, Sahin A, Merlin G. LdFlabarin, a new BAR domain membrane protein of Leishmania flagellum. PLoS One 2013; 8:e76380. [PMID: 24086735 PMCID: PMC3785460 DOI: 10.1371/journal.pone.0076380] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 08/23/2013] [Indexed: 11/18/2022] Open
Abstract
During the Leishmania life cycle, the flagellum undergoes successive assembly and disassembly of hundreds of proteins. Understanding these processes necessitates the study of individual components. Here, we investigated LdFlabarin, an uncharacterized L. donovani flagellar protein. The gene is conserved within the Leishmania genus and orthologous genes only exist in the Trypanosoma genus. LdFlabarin associates with the flagellar plasma membrane, extending from the base to the tip of the flagellum as a helicoidal structure. Site-directed mutagenesis, deletions and chimera constructs showed that LdFlabarin flagellar addressing necessitates three determinants: an N-terminal potential acylation site and a central BAR domain for membrane targeting and the C-terminal domain for flagellar specificity. In vitro, the protein spontaneously associates with liposomes, triggering tubule formation, which suggests a structural/morphogenetic function. LdFlabarin is the first characterized Leishmania BAR domain protein, and the first flagellum-specific BAR domain protein.
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Affiliation(s)
- Michèle Lefebvre
- CNRS UMR 5290, Montpellier, France
- Université Montpellier 1, Montpellier, France
- Centre Hospitalier Universitaire La Colombière, Montpellier, France
- IRD 224, Montpellier, France
| | - Emmanuel Tetaud
- CNRS UMR 5095, Institut de Biochimie Génétique et Cellulaire, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | - Magali Thonnus
- CNRS UMR 5234, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | - Bénédicte Salin
- CNRS UMR 5095, Institut de Biochimie Génétique et Cellulaire, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | - Fanny Boissier
- CNRS UMR 5095, Institut de Biochimie Génétique et Cellulaire, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | - Corinne Blancard
- CNRS UMR 5095, Institut de Biochimie Génétique et Cellulaire, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | - Cécile Sauvanet
- CNRS UMR 5095, Institut de Biochimie Génétique et Cellulaire, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | | | - Benoît Espiau
- CNRS-EPHE USR 3278, Papetoai, Moorea, Polynésie Française
| | - Annelise Sahin
- CNRS UMR 5234, Bordeaux, France
- Université Bordeaux Segalen, Bordeaux, France
| | - Gilles Merlin
- CNRS UMR 5290, Montpellier, France
- Université Montpellier 1, Montpellier, France
- Centre Hospitalier Universitaire La Colombière, Montpellier, France
- IRD 224, Montpellier, France
- * E-mail:
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39
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Zhang Q, Hu J, Ling K. Molecular views of Arf-like small GTPases in cilia and ciliopathies. Exp Cell Res 2013; 319:2316-22. [PMID: 23548655 PMCID: PMC3742637 DOI: 10.1016/j.yexcr.2013.03.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
Abstract
The primary cilia are microtubule-based organelles that protrude from most of the eukaryotic cells. Recognized as the cell's antenna, primary cilium functions as a signaling hub for many physiologically and developmentally important signaling cascades. Ciliary dysfunction causes a wide spectrum of syndromic human genetic diseases collectively termed "ciliopathies". Mounting evidences have shown that various small GTPases have been implicated in the context of cilia as well as human ciliopathies. However, how these small GTPases affect cilia formation and function remains poorly understood. Here we review and discuss the ciliary role of three Arf-like small GTPases (Arls), Arl3, Arl6, and Arl13b.
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Affiliation(s)
- Qing Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Jinghua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- NIH Mayo Translational PKD Center
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
- NIH Mayo Translational PKD Center
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40
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Chang L, Kreko T, Davison H, Cusmano T, Wu Y, Rothenfluh A, Eaton BA. Normal dynactin complex function during synapse growth in Drosophila requires membrane binding by Arfaptin. Mol Biol Cell 2013; 24:1749-64, S1-5. [PMID: 23596322 PMCID: PMC3667727 DOI: 10.1091/mbc.e12-09-0697] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 04/04/2013] [Accepted: 04/08/2013] [Indexed: 01/11/2023] Open
Abstract
Mutations in DCTN1, a component of the dynactin complex, are linked to neurodegenerative diseases characterized by a broad collection of neuropathologies. Because of the pleiotropic nature of dynactin complex function within the neuron, defining the causes of neuropathology in DCTN1 mutants has been difficult. We combined a genetic screen with cellular assays of dynactin complex function to identify genes that are critical for dynactin complex function in the nervous system. This approach identified the Drosophila homologue of Arfaptin, a multifunctional protein that has been implicated in membrane trafficking. We find that Arfaptin and the Drosophila DCTN1 homologue, Glued, function in the same pathway during synapse growth but not during axonal transport or synapse stabilization. Arfaptin physically associates with Glued and other dynactin complex components in the nervous system of both flies and mice and colocalizes with Glued at the Golgi in motor neurons. Mechanistically, membrane binding by Arfaptin mediates membrane association of the dynactin complex in motor neurons and is required for normal synapse growth. Arfaptin represents a novel dynactin complex-binding protein that specifies dynactin complex function during synapse growth.
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Affiliation(s)
- Leo Chang
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Tabita Kreko
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Holly Davison
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Tim Cusmano
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Yimin Wu
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
| | - Adrian Rothenfluh
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Benjamin A. Eaton
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229
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41
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Arf1 and membrane curvature cooperate to recruit Arfaptin2 to liposomes. PLoS One 2013; 8:e62963. [PMID: 23638170 PMCID: PMC3639266 DOI: 10.1371/journal.pone.0062963] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/27/2013] [Indexed: 11/19/2022] Open
Abstract
Arfaptin2 contains a Bin/Amphiphysin/Rvs (BAR) domain and directly interacts with proteins of the Arf/Arl family in their active GTP-bound state. It has been proposed that BAR domains are able to sense membrane curvature and to induce membrane tubulation. We report here that active Arf1 is required for the recruitment of Arfaptin2 to artificial liposomes mimicking the Golgi apparatus lipid composition. The Arf1-dependent recruitment of Arfaptin2 increases with membrane curvature, while the recruitment of Arf1 itself is not sensitive to curvature. At high protein concentrations, the binding of Arfaptin2 induces membrane tubulation. Finally, membrane-bound Arfaptin2 is released from the liposome when ArfGAP1 catalyzes the hydrolysis of GTP to GDP in Arf1. These results show that both Arf1 activation and high membrane curvature are required for efficient recruitment of Arfaptin2 to membranes.
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42
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Schwarz N, Hardcastle AJ, Cheetham ME. Arl3 and RP2 mediated assembly and traffic of membrane associated cilia proteins. Vision Res 2012; 75:2-4. [PMID: 22884633 DOI: 10.1016/j.visres.2012.07.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 01/17/2023]
Abstract
The traffic of proteins to the outer segment of photoreceptors is a fundamentally important process, which when perturbed results in photoreceptor cell death. Recent reports have revealed a novel pathway for the traffic of lipid-modified proteins involving the small GTPase Arl3 and its effectors PDEδ and Unc119. The retinitis pigmentosa protein RP2 is a GTPase activating protein (GAP) for Arl3 and also appears to regulate the assembly and traffic of membrane associated protein complexes. We recently identified the Gβ subunit of transducin (Gβ1) as a novel RP2 interacting protein. Our data support a role for RP2 in facilitating membrane association and traffic of Gβ1, potentially prior to the formation of the obligate Gβ:Gγ heterodimer. Here, we review the recent evidence that suggests that RP2 co-operates with Arl3 and its effectors in protein complex assembly and membrane specification for lipid-modified proteins. This is exemplified by the co-ordination of cilia associated traffic for heterotrimeric G proteins and we propose a model for the role of Arl3 and RP2 in this process.
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Affiliation(s)
- Nele Schwarz
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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43
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Abstract
As plant Golgi bodies move through the cell along the actin cytoskeleton, they face the need to maintain their polarized stack structure whilst receiving, processing and distributing protein cargo destined for secretion. Structural proteins, or Golgi matrix proteins, help to hold cisternae together and tethering factors direct cargo carriers to the correct target membranes. This review focuses on golgins, a protein family containing long coiled-coil regions, summarizes their known functions in animal cells and highlights recent findings about plant golgins and their putative roles in the plant secretory pathway.
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Affiliation(s)
- A Osterrieder
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK.
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44
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McKnight NC, Jefferies HBJ, Alemu EA, Saunders RE, Howell M, Johansen T, Tooze SA. Genome-wide siRNA screen reveals amino acid starvation-induced autophagy requires SCOC and WAC. EMBO J 2012; 31:1931-46. [PMID: 22354037 PMCID: PMC3343327 DOI: 10.1038/emboj.2012.36] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 01/23/2012] [Indexed: 01/10/2023] Open
Abstract
Autophagy is a catabolic process by which cytoplasmic components are sequestered and transported by autophagosomes to lysosomes for degradation, enabling recycling of these components and providing cells with amino acids during starvation. It is a highly regulated process and its deregulation contributes to multiple diseases. Despite its importance in cell homeostasis, autophagy is not fully understood. To find new proteins that modulate starvation-induced autophagy, we performed a genome-wide siRNA screen in a stable human cell line expressing GFP-LC3, the marker-protein for autophagosomes. Using stringent validation criteria, our screen identified nine novel autophagy regulators. Among the hits required for autophagosome formation are SCOC (short coiled-coil protein), a Golgi protein, which interacts with fasciculation and elongation protein zeta 1 (FEZ1), an ULK1-binding protein. SCOC forms a starvation-sensitive trimeric complex with UVRAG (UV radiation resistance associated gene) and FEZ1 and may regulate ULK1 and Beclin 1 complex activities. A second candidate WAC is required for starvation-induced autophagy but also acts as a potential negative regulator of the ubiquitin-proteasome system. The identification of these novel regulatory proteins with diverse functions in autophagy contributes towards a fuller understanding of autophagosome formation.
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Affiliation(s)
- Nicole C McKnight
- Secretory Pathways Laboratory, London Research Institute, Cancer Research UK, London, UK
| | - Harold B J Jefferies
- Secretory Pathways Laboratory, London Research Institute, Cancer Research UK, London, UK
| | - Endalkachew A Alemu
- Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Rebecca E Saunders
- High-Throughput Screening Lab, London Research Institute, Cancer Research UK, London, UK
| | - Michael Howell
- High-Throughput Screening Lab, London Research Institute, Cancer Research UK, London, UK
| | - Terje Johansen
- Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Sharon A Tooze
- Secretory Pathways Laboratory, London Research Institute, Cancer Research UK, London, UK
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45
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Houghton FJ, Bellingham SA, Hill AF, Bourges D, Ang DK, Gemetzis T, Gasnereau I, Gleeson PA. Arl5b is a Golgi-localised small G protein involved in the regulation of retrograde transport. Exp Cell Res 2012; 318:464-77. [DOI: 10.1016/j.yexcr.2011.12.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 12/04/2011] [Accepted: 12/28/2011] [Indexed: 11/30/2022]
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46
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Wright KJ, Baye LM, Olivier-Mason A, Mukhopadhyay S, Sang L, Kwong M, Wang W, Pretorius PR, Sheffield VC, Sengupta P, Slusarski DC, Jackson PK. An ARL3-UNC119-RP2 GTPase cycle targets myristoylated NPHP3 to the primary cilium. Genes Dev 2011; 25:2347-60. [PMID: 22085962 DOI: 10.1101/gad.173443.111] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The membrane of the primary cilium is a highly specialized compartment that organizes proteins to achieve spatially ordered signaling. Disrupting ciliary organization leads to diseases called ciliopathies, with phenotypes ranging from retinal degeneration and cystic kidneys to neural tube defects. How proteins are selectively transported to and organized in the primary cilium remains unclear. Using a proteomic approach, we identified the ARL3 effector UNC119 as a binding partner of the myristoylated ciliopathy protein nephrocystin-3 (NPHP3). We mapped UNC119 binding to the N-terminal 200 residues of NPHP3 and found the interaction requires myristoylation. Creating directed mutants predicted from a structural model of the UNC119-myristate complex, we identified highly conserved phenylalanines within a hydrophobic β sandwich to be essential for myristate binding. Furthermore, we found that binding of ARL3-GTP serves to release myristoylated cargo from UNC119. Finally, we showed that ARL3, UNC119b (but not UNC119a), and the ARL3 GAP Retinitis Pigmentosa 2 (RP2) are required for NPHP3 ciliary targeting and that targeting requires UNC119b myristoyl-binding activity. Our results uncover a selective, membrane targeting GTPase cycle that delivers myristoylated proteins to the ciliary membrane and suggest that other myristoylated proteins may be similarly targeted to specialized membrane domains.
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Affiliation(s)
- Kevin J Wright
- Genentech Inc., South San Francisco, California 94080, USA
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47
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Demmel L, Melak M, Kotisch H, Fendos J, Reipert S, Warren G. Differential selection of Golgi proteins by COPII Sec24 isoforms in procyclic Trypanosoma brucei. Traffic 2011; 12:1575-91. [PMID: 21801288 DOI: 10.1111/j.1600-0854.2011.01257.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Sec24 subunit of the coat protein complex II (COPII) has been implicated in selecting newly synthesized cargo from the endoplasmic reticulum (ER) for delivery to the Golgi. The protozoan parasite, Trypanosoma brucei, contains two paralogs, TbSec24.1 and TbSec24.2, which were depleted using RNA interference in the insect form of the parasite. Depletion of either TbSec24.1 or TbSec24.2 resulted in growth arrest and modest inhibition of anterograde transport of the putative Golgi enzyme, TbGntB, and the secretory marker, BiPNAVRG-HA9. In contrast, depletion of TbSec24.1, but not TbSec24.2, led to reversible mislocalization of the Golgi stack proteins, TbGRASP and TbGolgin63. The latter accumulated in the ER. The localization of the COPI coatomer subunit, TbεCOP, and the trans Golgi network (TGN) protein, TbGRIP70, was largely unaffected, although the latter was preferentially lost from those Golgi that were not associated with the bilobe, a structure previously implicated in Golgi biogenesis. Together, these data suggest that TbSec24 paralogs can differentiate among proteins destined for the Golgi.
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Affiliation(s)
- Lars Demmel
- Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
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48
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Qin Y, Shi F, Tang C. Molecular characterization and expression analysis of cDNAs encoding four Rab and two Arf GTPases in the latex of Hevea brasiliensis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:729-737. [PMID: 21530287 DOI: 10.1016/j.plaphy.2011.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 03/01/2011] [Indexed: 05/30/2023]
Abstract
In plants, Rab and Arf GTPases are key regulators of vesicle trafficking. To investigate whether these small GTPases (SG) play a role in the regulation of the regeneration of latex (the cytoplasm of the rubber-producing laticifer cell) in Hevea brasiliensis (Hevea hereafter), full-length cDNAs that encode four HbRab and two HbArf GTPases were cloned. The four HbRab proteins showed specific GTP-binding activity when expressed in Escherichia coli. Transcript expression of the six SG genes was investigated by real-time RT-PCR. All genes revealed to be expressed in each of the six Hevea tissues examined, but the expression patterns were different. Four genes, HbArf1, HbRab2, HbRab3 and HbRab4, displayed a preferential expression in latex. The expression of all genes was upregulated by the act of latex exploitation (tapping), and HbRab1 had the highest level of upregulation. Wounding markedly upregulated the expression of two SG genes (HbRab1 and HbArf2), and exogenous methyl jasmonate upregulated all six SG genes. Wounding might upregulate the expression of HbRab1 and HbArf2 through a jasmonic acid-mediated signaling pathway. None of the genes were markedly upregulated by Ethrel (an ethylene releaser and latex stimulator); instead, HbArf2 and HbRab4 were downregulated significantly after a 24 h treatment with Ethrel. This paper gives the first description of Rab and Arf GTPases in Hevea and provides clues for their involvement, HbRab1 in particular, in latex regeneration.
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Affiliation(s)
- Yunxia Qin
- Key Lab of Rubber Biology, Ministry of Agriculture & Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Danzhou, Hainan 571737, China
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49
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Abstract
A number of long coiled-coil proteins are present on the Golgi. Often referred to as "golgins," they are well conserved in evolution and at least five are likely to have been present in the last common ancestor of all eukaryotes. Individual golgins are found in different parts of the Golgi stack, and they are typically anchored to the membrane at their carboxyl termini by a transmembrane domain or by binding a small GTPase. They appear to have roles in membrane traffic and Golgi structure, but their precise function is in most cases unclear. Many have binding sites for Rab family GTPases along their length, and this has led to the suggestion that the golgins act collectively to form a tentacular matrix that surrounds the Golgi to capture Rab-coated membranes in the vicinity of the stack. Such a collective role might explain the lack of cell lethality seen following loss of some of the genes in human familial conditions or mouse models.
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50
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Abstract
The eukaryotic Golgi apparatus is characterized by a stack of flattened cisternae that are surrounded by transport vesicles. The organization and function of the Golgi require Golgi matrix proteins, including GRASPs and golgins, which exist primarily as fiber-like bridges between Golgi cisternae or between cisternae and vesicles. In this review, we highlight recent findings on Golgi matrix proteins, including their roles in maintaining the Golgi structure, vesicle tethering, and novel, unexpected functions. These new discoveries further our understanding of the molecular mechanisms that maintain the structure and the function of the Golgi, as well as its relationship with other cellular organelles such as the centrosome.
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