1
|
Shinoda S, Sakai Y, Matsui T, Uematsu M, Koyama-Honda I, Sakamaki JI, Yamamoto H, Mizushima N. Syntaxin 17 recruitment to mature autophagosomes is temporally regulated by PI4P accumulation. eLife 2024; 12:RP92189. [PMID: 38831696 DOI: 10.7554/elife.92189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
During macroautophagy, cytoplasmic constituents are engulfed by autophagosomes. Lysosomes fuse with closed autophagosomes but not with unclosed intermediate structures. This is achieved in part by the late recruitment of the autophagosomal SNARE syntaxin 17 (STX17) to mature autophagosomes. However, how STX17 recognizes autophagosome maturation is not known. Here, we show that this temporally regulated recruitment of STX17 depends on the positively charged C-terminal region of STX17. Consistent with this finding, mature autophagosomes are more negatively charged compared with unclosed intermediate structures. This electrostatic maturation of autophagosomes is likely driven by the accumulation of phosphatidylinositol 4-phosphate (PI4P) in the autophagosomal membrane. Accordingly, dephosphorylation of autophagosomal PI4P prevents the association of STX17 to autophagosomes. Furthermore, molecular dynamics simulations support PI4P-dependent membrane insertion of the transmembrane helices of STX17. Based on these findings, we propose a model in which STX17 recruitment to mature autophagosomes is temporally regulated by a PI4P-driven change in the surface charge of autophagosomes.
Collapse
Affiliation(s)
- Saori Shinoda
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yuji Sakai
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Takahide Matsui
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Masaaki Uematsu
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Ikuko Koyama-Honda
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Jun-Ichi Sakamaki
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hayashi Yamamoto
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Molecular Oncology, Institute for Advanced Medical Sciences, Nippon Medical School, Tokyo, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduated School of Medicine, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
2
|
Liu J, Xu M, Ni B, Zhang Z, Gao X, Zhang D, Yang L, Ye Z, Wen J, Liu P. Metformin Therapeutic Targets for Aortic Aneurysms: A Mendelian Randomization and Colocalization Study. Rev Cardiovasc Med 2024; 25:89. [PMID: 39076954 PMCID: PMC11263823 DOI: 10.31083/j.rcm2503089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/29/2023] [Accepted: 11/16/2023] [Indexed: 07/31/2024] Open
Abstract
Background Identifying effective pharmacological interventions to prevent the progressive enlargement and rupture of aortic aneurysms (AAs) is critical. Previous studies have suggested links between metformin use and a decreased incidence of AAs. In this study, we employed Mendelian randomization (MR) to investigate causal effects of metformin's targets on AA risk and to explore the underlying mechanisms underlying these effects. Methods To examine the relationship between metformin use and AA risk, we implemented both two-sample MR and multivariable MR analyses. Utilizing genetic instrumental variables, we retrieved cis-expression quantitative trait loci (cis-eQTL) data for potential targets of metformin from the Expression Quantitative Trait Loci Genetics Consortium (eQTLGen) Consortium and Genotype-Tissue Expression (GTEx) project. Colocalization analysis was employed to ascertain the probability of shared causal genetic variants between single nucleotide polymorphisms (SNPs) associated with eQTLs and AA. Results Our findings reveal that metformin use reduces AA risk, exhibiting a protective effect with an odds ratio (OR) of 4.88 × 10 - 3 (95% confidence interval [CI]: 7.30 × 10 - 5 -0.33, p = 0.01). Furthermore, the protective effect of type 2 diabetes on AA risk appears to be driven by metformin use ( OR MVMR = 1.34 × 10 - 4 , 95% CI: 3.97 × 10 - 8 -0.45, p = 0.03). Significant Mendelian randomization (MR) results were observed for the expression of two metformin-related genes in the bloodstream: NADH:ubiquinone oxidoreductase subunit A6 (NDUFA6) and cytochrome b5 type B (CYB5B), across two independent datasets ( OR CYB5B = 1.35, 95% CI: 1.20-1.51, p = 2.41 × 10 - 7 ; OR NDUFA6 = 1.12; 95% CI: 1.07-1.17, p = 1.69 × 10 - 6 ). The MR analysis of tissue-specific expression also demonstrated a positive correlation between increased NDUFA6 expression and heightened AA risk. Lastly, NDUFA6 exhibited evidence of colocalization with AA. Conclusions Our study suggests that metformin may play a significant role in lowering the risk of AA. This protective effect could potentially be linked to the mitigation of mitochondrial and immune dysfunction. Overall, NDUFA6 has emerged as a potential mechanism through which metformin intervention may confer AA protection.
Collapse
Affiliation(s)
- Jingwen Liu
- Peking University China‐Japan Friendship School of Clinical Medicine, 100029 Beijing, China
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| | - Mingyuan Xu
- Peking University China‐Japan Friendship School of Clinical Medicine, 100029 Beijing, China
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| | - Bin Ni
- Peking University China‐Japan Friendship School of Clinical Medicine, 100029 Beijing, China
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| | - Zhaohua Zhang
- Peking University China‐Japan Friendship School of Clinical Medicine, 100029 Beijing, China
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| | - Xixi Gao
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
- China-Japan Friendship Hospital (Institute of Clinical Medical Sciences), Chinese Academy of Medical Sciences & Peking Union Medical College, 100029 Beijing, China
| | - Dingkai Zhang
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
- China-Japan Friendship Hospital (Institute of Clinical Medical Sciences), Chinese Academy of Medical Sciences & Peking Union Medical College, 100029 Beijing, China
| | - Liang Yang
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
- China-Japan Friendship Hospital (Institute of Clinical Medical Sciences), Chinese Academy of Medical Sciences & Peking Union Medical College, 100029 Beijing, China
| | - Zhidong Ye
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| | - Jianyan Wen
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| | - Peng Liu
- Peking University China‐Japan Friendship School of Clinical Medicine, 100029 Beijing, China
- Department of Cardiovascular Surgery, China-Japan Friendship Hospital, 100029 Beijing, China
| |
Collapse
|
3
|
Naón D, Hernández-Alvarez MI, Shinjo S, Wieczor M, Ivanova S, Martins de Brito O, Quintana A, Hidalgo J, Palacín M, Aparicio P, Castellanos J, Lores L, Sebastián D, Fernández-Veledo S, Vendrell J, Joven J, Orozco M, Zorzano A, Scorrano L. Splice variants of mitofusin 2 shape the endoplasmic reticulum and tether it to mitochondria. Science 2023; 380:eadh9351. [PMID: 37347868 DOI: 10.1126/science.adh9351] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 05/12/2023] [Indexed: 06/24/2023]
Abstract
In eukaryotic cells, different organelles interact at membrane contact sites stabilized by tethers. Mitochondrial mitofusin 2 (MFN2) acts as a membrane tether that interacts with an unknown partner on the endoplasmic reticulum (ER). In this work, we identified the MFN2 splice variant ERMIT2 as the ER tethering partner of MFN2. Splicing of MFN2 produced ERMIT2 and ERMIN2, two ER-specific variants. ERMIN2 regulated ER morphology, whereas ERMIT2 localized at the ER-mitochondria interface and interacted with mitochondrial mitofusins to tether ER and mitochondria. This tethering allowed efficient mitochondrial calcium ion uptake and phospholipid transfer. Expression of ERMIT2 ameliorated the ER stress, inflammation, and fibrosis typical of liver-specific Mfn2 knockout mice. Thus, ER-specific MFN2 variants display entirely extramitochondrial MFN2 functions involved in interorganellar tethering and liver metabolic activities.
Collapse
Affiliation(s)
- Déborah Naón
- Department of Biology, University of Padua, 35121 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | - María Isabel Hernández-Alvarez
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
- IBUB, Universitat de Barcelona, Barcelona, Spain
| | - Satoko Shinjo
- Department of Biology, University of Padua, 35121 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
| | - Milosz Wieczor
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Department of Physical Chemistry, Gdansk University of Technology, 80-233 Gdańsk, Poland
| | - Saska Ivanova
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | | | - Albert Quintana
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Department of Cellular Biology, Physiology and Immunology, Animal Physiology Unit, Faculty of Biosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Juan Hidalgo
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Department of Cellular Biology, Physiology and Immunology, Animal Physiology Unit, Faculty of Biosciences, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Manuel Palacín
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Pilar Aparicio
- Department of Orthopaedics and Trauma Surgery, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Barcelona, Spain
| | - Juan Castellanos
- Department of Orthopaedics and Trauma Surgery, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Barcelona, Spain
| | - Luis Lores
- Pneumology Department, Hospital General Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Barcelona, Spain
| | - David Sebastián
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Sonia Fernández-Veledo
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
- Department of Endocrinology and Nutrition, Hospital Universitari de Tarragona Joan XXIII, Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, Spain
- Medicine School, Universitat Rovira i Virgili, Tarragona and Reus, Spain
| | - Joan Vendrell
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
- Department of Endocrinology and Nutrition, Hospital Universitari de Tarragona Joan XXIII, Institut d'Investigació Sanitària Pere Virgili (IISPV), Tarragona, Spain
- Medicine School, Universitat Rovira i Virgili, Tarragona and Reus, Spain
| | - Jorge Joven
- Medicine School, Universitat Rovira i Virgili, Tarragona and Reus, Spain
- Unitat de Recerca Biomèdica, Institut d'Investigació Sanitària Pere Virgili, Hospital Universitari de Sant Joan, Reus, Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Luca Scorrano
- Department of Biology, University of Padua, 35121 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
| |
Collapse
|
4
|
Kozono T, Jogano C, Okumura W, Sato H, Matsui H, Takagi T, Okumura N, Takao T, Tonozuka T, Nishikawa A. Cleavage of the Jaw1 C-terminal region enhances its augmentative effect on the Ca2+ release via IP3 receptors. J Cell Sci 2023; 136:287037. [PMID: 36789796 DOI: 10.1242/jcs.260439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 01/17/2023] [Indexed: 02/16/2023] Open
Abstract
Jaw1 (also known as IRAG2), a tail-anchored protein with 39 carboxyl (C)-terminal amino acids, is oriented to the lumen of the endoplasmic reticulum and outer nuclear membrane. We previously reported that Jaw1, as a member of the KASH protein family, plays a role in maintaining nuclear shape via its C-terminal region. Furthermore, we recently reported that Jaw1 functions as an augmentative effector of Ca2+ release from the endoplasmic reticulum by interacting with the inositol 1,4,5-trisphosphate receptors (IP3Rs). Intriguingly, the C-terminal region is partially cleaved, meaning that Jaw1 exists in the cell in at least two forms - uncleaved and cleaved. However, the mechanism of the cleavage event and its physiological significance remain to be determined. In this study, we demonstrate that the C-terminal region of Jaw1 is cleaved after its insertion by the signal peptidase complex (SPC). Particularly, our results indicate that the SPC with the catalytic subunit SEC11A, but not SEC11C, specifically cleaves Jaw1. Furthermore, using a mutant with a defect in the cleavage event, we demonstrate that the cleavage event enhances the augmentative effect of Jaw1 on the Ca2+ release ability of IP3Rs.
Collapse
Affiliation(s)
- Takuma Kozono
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Chifuyu Jogano
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Wataru Okumura
- Department of Food and Energy Systems Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hiroyuki Sato
- Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hitomi Matsui
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Tsubasa Takagi
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Nobuaki Okumura
- Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Toshifumi Takao
- Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Takashi Tonozuka
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Atsushi Nishikawa
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.,Department of Food and Energy Systems Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.,Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| |
Collapse
|
5
|
Mehlhorn DG, Asseck LY, Grefen C. Looking for a safe haven: tail-anchored proteins and their membrane insertion pathways. PLANT PHYSIOLOGY 2021; 187:1916-1928. [PMID: 35235667 PMCID: PMC8644595 DOI: 10.1093/plphys/kiab298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/05/2021] [Indexed: 06/14/2023]
Abstract
Insertion of membrane proteins into the lipid bilayer is a crucial step during their biosynthesis. Eukaryotic cells face many challenges in directing these proteins to their predestined target membrane. The hydrophobic signal peptide or transmembrane domain (TMD) of the nascent protein must be shielded from the aqueous cytosol and its target membrane identified followed by transport and insertion. Components that evolved to deal with each of these challenging steps range from chaperones to receptors, insertases, and sophisticated translocation complexes. One prominent translocation pathway for most proteins is the signal recognition particle (SRP)-dependent pathway which mediates co-translational translocation of proteins across or into the endoplasmic reticulum (ER) membrane. This textbook example of protein insertion is stretched to its limits when faced with secretory or membrane proteins that lack an amino-terminal signal sequence or TMD. Particularly, a large group of so-called tail-anchored (TA) proteins that harbor a single carboxy-terminal TMD require an alternative, post-translational insertion route into the ER membrane. In this review, we summarize the current research in TA protein insertion with a special focus on plants, address challenges, and highlight future research avenues.
Collapse
Affiliation(s)
- Dietmar G Mehlhorn
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Lisa Y Asseck
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| | - Christopher Grefen
- Faculty of Biology and Biotechnology, Molecular and Cellular Botany, University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany
| |
Collapse
|
6
|
Kumar T, Maitra S, Rahman A, Bhattacharjee S. A conserved guided entry of tail-anchored pathway is involved in the trafficking of a subset of membrane proteins in Plasmodium falciparum. PLoS Pathog 2021; 17:e1009595. [PMID: 34780541 PMCID: PMC8629386 DOI: 10.1371/journal.ppat.1009595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 11/29/2021] [Accepted: 10/19/2021] [Indexed: 01/22/2023] Open
Abstract
Tail-anchored (TA) proteins are defined by the absence of N-terminus signal sequence and the presence of a single transmembrane domain (TMD) proximal to their C-terminus. They play fundamental roles in cellular processes including vesicular trafficking, protein translocation and quality control. Some of the TA proteins are post-translationally integrated by the Guided Entry of TA (GET) pathway to the cellular membranes; with their N-terminus oriented towards the cytosol and C-terminus facing the organellar lumen. The TA repertoire and the GET machinery have been extensively characterized in the yeast and mammalian systems, however, they remain elusive in the human malaria parasite Plasmodium falciparum. In this study, we bioinformatically predicted a total of 63 TA proteins in the P. falciparum proteome and revealed the association of a subset with the P. falciparum homolog of Get3 (PfGet3). In addition, our proximity labelling studies either definitively identified or shortlisted the other eligible GET constituents, and our in vitro association studies validated associations between PfGet3 and the corresponding homologs of Get4 and Get2 in P. falciparum. Collectively, this study reveals the presence of proteins with hallmark TA signatures and the involvement of evolutionary conserved GET trafficking pathway for their targeted delivery within the parasite. Tail-anchored (TA) membrane proteins are known to play essential cellular functions in the eukaryotes. These proteins are trafficked to their respective destinations by post-translational translocation pathways that are evolutionarily conserved from yeast to human. However, they remain unidentified in the malaria parasite Plasmodium falciparum. We have used bioinformatic prediction algorithms in conjunction with functional validation studies to identify the candidate TA repertoire and some of the homologs of the trafficking machinery in P. falciparum. Initially, we predicted the presence of 63 putative TA proteins localized to distinct compartments within this parasite, including a few confirmed TA homologs in other eukaryotic systems. We then identified and characterized PfGet3 as a central component in the Guided-Entry of TA (GET) translocation machinery, and our bacterial co-expression and pulldown assays with two selected recombinant TA proteins, PfBOS1 and PfUSE1, showed co-association with PfGet3. We also identified PfGet2 and PfGet4 as the other two components of the GET machinery in P. falciparum using proximity biotinylation followed by mass spectrometry. Interestingly, we also found six TA proteins in the parasite enriched in this fraction. We further validated the direct interactions between a few TA candidates, PfGet4 and PfGet2 with PfGet3 using recombinant-based pulldown studies. In conclusion, this study classified a subset of membrane proteins with the TA nomenclature and implicated a previously unidentified GET pathway for their translocation in this apicomplexan parasite.
Collapse
Affiliation(s)
- Tarkeshwar Kumar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Satarupa Maitra
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Abdur Rahman
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Souvik Bhattacharjee
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
- * E-mail:
| |
Collapse
|
7
|
Farkas Á, Bohnsack KE. Capture and delivery of tail-anchored proteins to the endoplasmic reticulum. J Cell Biol 2021; 220:212470. [PMID: 34264263 PMCID: PMC8287540 DOI: 10.1083/jcb.202105004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/20/2021] [Accepted: 06/22/2021] [Indexed: 11/22/2022] Open
Abstract
Tail-anchored (TA) proteins fulfill diverse cellular functions within different organellar membranes. Their characteristic C-terminal transmembrane segment renders TA proteins inherently prone to aggregation and necessitates their posttranslational targeting. The guided entry of TA proteins (GET in yeast)/transmembrane recognition complex (TRC in humans) pathway represents a major route for TA proteins to the endoplasmic reticulum (ER). Here, we review important new insights into the capture of nascent TA proteins at the ribosome by the GET pathway pretargeting complex and the mechanism of their delivery into the ER membrane by the GET receptor insertase. Interestingly, several alternative routes by which TA proteins can be targeted to the ER have emerged, raising intriguing questions about how selectivity is achieved during TA protein capture. Furthermore, mistargeting of TA proteins is a fundamental cellular problem, and we discuss the recently discovered quality control machineries in the ER and outer mitochondrial membrane for displacing mislocalized TA proteins.
Collapse
Affiliation(s)
- Ákos Farkas
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| |
Collapse
|
8
|
Pereira RFS, de Carvalho CCCR. Optimization of Multiparameters for Increased Yields of Cytochrome B5 in Bioreactors. Molecules 2021; 26:4148. [PMID: 34299423 PMCID: PMC8306036 DOI: 10.3390/molecules26144148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 11/26/2022] Open
Abstract
The production of recombinant proteins is gaining increasing importance as the market requests high quality proteins for several applications. However, several process parameters affect both the growth of cells and product yields. This study uses high throughput systems and statistical methods to assess the influence of fermentation conditions in lab-scale bioreactors. Using this methodology, it was possible to find the best conditions to produce cytochrome b5 with recombinant cells of Escherichia coli. Using partial least squares, the height-to-diameter ratio of the bioreactor, aeration rate, and PID controller parameters were found to contribute significantly to the final biomass and cytochrome concentrations. Hence, we could use this information to fine-tune the process parameters, which increased cytochrome production and yield several-fold. Using aeration of 1 vvm, a bioreactor with a height-to-ratio of 2.4 and tuned PID parameters, a production of 72.72 mg/L of cytochrome b5 in the culture media, and a maximum of product to biomass yield of 24.97 mg/g could be achieved.
Collapse
Affiliation(s)
- Ricardo F. S. Pereira
- Department of Bioengineering, iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal;
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Carla C. C. R. de Carvalho
- Department of Bioengineering, iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal;
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| |
Collapse
|
9
|
Bentebbal SA, Meqbel BR, Salter A, Allan V, Burke B, Horn HF. A human infertility-associated KASH5 variant promotes mitochondrial localization. Sci Rep 2021; 11:10133. [PMID: 33980926 PMCID: PMC8115505 DOI: 10.1038/s41598-021-89439-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/22/2021] [Indexed: 02/03/2023] Open
Abstract
KASH5 is the most recently identified member of the KASH domain family of tail anchored, outer nuclear membrane (ONM) and endoplasmic reticulum (ER) proteins. During meiosis prophase I, KASH5 and SUN1 form a complex that spans the nuclear envelope and which links the telomeres of meiotic chromosomes to cytoplasmic dynein. This connection is essential for homologous chromosome dynamics and pairing. A recent study identified a variant in human KASH5 (L535Q) that correlated with male infertility associated with azoospermia. However, no molecular mechanism was described. Here, we report that this amino acid substitution, within the KASH5 transmembrane domain (TMD) has no predicted effects on secondary structure. However, the overall hydrophobicity of the L535Q TMD, is calculated to be lower than the wild-type KASH5, based on the GES (Goldman-Engelman-Steitz) amino acid hydrophobicity scale. This change in hydrophobicity profoundly affects the subcellular localization of KASH5. Through a series of amino acid substitution studies, we show that the L535Q substitution perturbs KASH5 localization to the ER and ONM and instead results in mistargeting to the mitochondria membrane. We suggest that this mislocalization accounts for the infertility and azoospermia phenotype in patients.
Collapse
Affiliation(s)
- Sana A. Bentebbal
- grid.452146.00000 0004 1789 3191College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Bakhita R. Meqbel
- grid.452146.00000 0004 1789 3191College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Anna Salter
- grid.5379.80000000121662407Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT UK ,grid.185448.40000 0004 0637 0221Laboratory of Nuclear Dynamics and Architecture, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Victoria Allan
- grid.5379.80000000121662407Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT UK
| | - Brian Burke
- grid.185448.40000 0004 0637 0221Laboratory of Nuclear Dynamics and Architecture, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Henning F. Horn
- grid.452146.00000 0004 1789 3191College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| |
Collapse
|
10
|
Jiang H. Quality control pathways of tail-anchored proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118922. [PMID: 33285177 DOI: 10.1016/j.bbamcr.2020.118922] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/14/2020] [Accepted: 12/01/2020] [Indexed: 12/20/2022]
Abstract
Tail-anchored (TA) proteins have an N-terminal domain in the cytosol and a C-terminal transmembrane domain anchored to a variety of organelle membranes. TA proteins are recognized by targeting factors at the transmembrane domain and C-terminal sequence and are guided to distinct membranes. The promiscuity of targeting sequences and the dysfunction of targeting pathways cause mistargeting of TA proteins. TA proteins are under surveillance by quality control pathways. For resident TA proteins at mitochondrial and ER membranes, intrinsic instability or stimuli induced degrons of the cytosolic and transmembrane domains are sensed by quality control factors to initiate degradation of TA proteins. These pathways are summarized as TA protein degradation-Cytosol (TAD-C) and TAD-Membrane (TAD-M) pathways. For mistargeted and a subset of solitary TA proteins at mitochondrial and peroxisomal membranes, a unique pathway has been revealed in recent years. Msp1/ATAD1 is an AAA-ATPase dually-localized to mitochondrial and peroxisomal membranes. It directly recognizes mistargeted and solitary TA proteins and dislocates them out of membrane. Dislocated substrates are subsequently ubiquitinated by the ER-resident Doa10 ubiquitin E3 ligase complex for degradation. We summarize and discuss the substrate recognition, dislocation and degradation mechanisms of the Msp1 pathway.
Collapse
Affiliation(s)
- Hui Jiang
- National Institute of Biological Sciences, Beijing 102206, China; Beijing Key Laboratory of Cell Biology for Animal Aging, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100871, China.
| |
Collapse
|
11
|
Schiavon CR, Zhang T, Zhao B, Moore AS, Wales P, Andrade LR, Wu M, Sung TC, Dayn Y, Feng JW, Quintero OA, Shadel GS, Grosse R, Manor U. Actin chromobody imaging reveals sub-organellar actin dynamics. Nat Methods 2020; 17:917-921. [PMID: 32778832 PMCID: PMC7746311 DOI: 10.1038/s41592-020-0926-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 07/15/2020] [Indexed: 12/31/2022]
Abstract
The actin cytoskeleton plays multiple critical roles in cells, from cell migration to organelle dynamics. The small and transient actin structures regulating organelle dynamics are challenging to detect with fluorescence microscopy, making it difficult to determine whether actin filaments are directly associated with specific membranes. To address these limitations, we developed fluorescent-protein-tagged actin nanobodies, termed 'actin chromobodies' (ACs), targeted to organelle membranes to enable high-resolution imaging of sub-organellar actin dynamics.
Collapse
Affiliation(s)
- Cara R Schiavon
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
- Molecular and Cellular Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Tong Zhang
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Bing Zhao
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Andrew S Moore
- Janelia Research Campus, Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Pauline Wales
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
- Molecular and Cellular Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Leonardo R Andrade
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Melissa Wu
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Tsung-Chang Sung
- Transgenic Core, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Yelena Dayn
- Transgenic Core, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Jasmine W Feng
- Department of Biology, University of Richmond, Richmond, VA, USA
| | - Omar A Quintero
- Department of Biology, University of Richmond, Richmond, VA, USA
| | - Gerald S Shadel
- Molecular and Cellular Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Robert Grosse
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA.
| |
Collapse
|
12
|
Bocanegra JL, Fujita BM, Melton NR, Cowan JM, Schinski EL, Tamir TY, Major MB, Quintero OA. The MyMOMA domain of MYO19 encodes for distinct Miro-dependent and Miro-independent mechanisms of interaction with mitochondrial membranes. Cytoskeleton (Hoboken) 2020; 77:149-166. [PMID: 31479585 PMCID: PMC8556674 DOI: 10.1002/cm.21560] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/13/2019] [Accepted: 08/31/2019] [Indexed: 08/19/2023]
Abstract
MYO19 interacts with mitochondria through a C-terminal membrane association domain (MyMOMA). Specific mechanisms for localization of MYO19 to mitochondria are poorly understood. Using promiscuous biotinylation data in combination with existing affinity-capture databases, we have identified a number of putative MYO19-interacting proteins. We chose to explore the interaction between MYO19 and the mitochondrial GTPase Miro2 by expressing mchr-Miro2 in combination with GFP-tagged fragments of the MyMOMA domain and assaying for recruitment of MYO19-GFP to mitochondria. Coexpression of MYO19898-970 -GFP with mchr-Miro2 enhanced MYO19898-970 -GFP localization to mitochondria. Mislocalizing Miro2 to filopodial tips or the cytosolic face of the nuclear envelope did not recruit MYO19898-970 -GFP to either location. To address the kinetics of the Miro2/MYO19 interaction, we used FRAP analysis and permeabilization-activated reduction in fluorescence analysis. MyMOMA constructs containing a putative membrane-insertion motif but lacking the Miro2-interacting region displayed slow exchange kinetics. MYO19898-970 -GFP, which does not include the membrane-insertion motif, displayed rapid exchange kinetics, suggesting that MYO19 interacting with Miro2 has higher mobility than MYO19 inserted into the mitochondrial outer membrane. Mutation of well-conserved, charged residues within MYO19 or within the switch I and II regions of Miro2 abolished the enhancement of MYO19898-970 -GFP localization in cells ectopically expressing mchr-Miro2. Additionally, expressing mutant versions of Miro2 thought to represent particular nucleotide states indicated that the enhancement of MYO19898-970 -GFP localization is dependent on Miro2 nucleotide state. Taken together, these data suggest that membrane-inserted MYO19 is part of a larger complex, and that Miro2 plays a role in integration of actin- and microtubule-based mitochondrial activities.
Collapse
Affiliation(s)
| | | | | | - James M. Cowan
- Department of Biology, University of Richmond, Richmond, Virginia
| | | | - Tigist Y. Tamir
- Department of Pharmacology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina
| | - Michael B. Major
- Department of Pharmacology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina
- Department of Cell Biology and Physiology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina Chapel Hill, Chapel Hill, North Carolina
| | - Omar A. Quintero
- Department of Biology, University of Richmond, Richmond, Virginia
| |
Collapse
|
13
|
Abstract
Due to their topology tail-anchored (TA) proteins must target to the membrane independently of the co-translational route defined by the signal sequence recognition particle (SRP), its receptor and the translocon Sec61. More than a decade of work has extensively characterized a highly conserved pathway, the yeast GET or mammalian TRC40 pathway, which is capable of countering the biogenetic challenge posed by the C-terminal TA anchor. In this review we briefly summarize current models of this targeting route and focus on emerging aspects such as the intricate interplay with the proteostatic network of cells and with other targeting pathways. Importantly, we consider the lessons provided by the in vivo analysis of the pathway in different model organisms and by the consideration of its full client spectrum in more recent studies. This analysis of the state of the field highlights directions in which the current models may be experimentally probed and conceptually extended.
Collapse
Affiliation(s)
- Nica Borgese
- Institute of Neuroscience and BIOMETRA Department, Consiglio Nazionale delle Ricerche and Università degli Studi di Milano, via Vanvitelli 32, 20129, Milan, Italy.
| | - Javier Coy-Vergara
- Department of Molecular Biology, University of Göttingen Medical Centre, Humboldtallee 23, 37073, Göttingen, Germany
| | - Sara Francesca Colombo
- Institute of Neuroscience and BIOMETRA Department, Consiglio Nazionale delle Ricerche and Università degli Studi di Milano, via Vanvitelli 32, 20129, Milan, Italy
| | - Blanche Schwappach
- Department of Molecular Biology, University of Göttingen Medical Centre, Humboldtallee 23, 37073, Göttingen, Germany.
| |
Collapse
|
14
|
Coy-Vergara J, Rivera-Monroy J, Urlaub H, Lenz C, Schwappach B. A trap mutant reveals the physiological client spectrum of TRC40. J Cell Sci 2019; 132:jcs.230094. [PMID: 31182645 PMCID: PMC6633398 DOI: 10.1242/jcs.230094] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 05/31/2019] [Indexed: 12/13/2022] Open
Abstract
The transmembrane recognition complex (TRC) pathway targets tail-anchored (TA) proteins to the membrane of the endoplasmic reticulum (ER). While many TA proteins are known to be able to use this pathway, it is essential for the targeting of only a few. Here, we uncover a large number of TA proteins that engage with TRC40 when other targeting machineries are fully operational. We use a dominant-negative ATPase-impaired mutant of TRC40 in which aspartate 74 was replaced by a glutamate residue to trap TA proteins in the cytoplasm. Manipulation of the hydrophobic TA-binding groove in TRC40 (also known as ASNA1) reduces interaction with most, but not all, substrates suggesting that co-purification may also reflect interactions unrelated to precursor protein targeting. We confirm known TRC40 substrates and identify many additional TA proteins interacting with TRC40. By using the trap approach in combination with quantitative mass spectrometry, we show that Golgi-resident TA proteins such as the golgins golgin-84, CASP and giantin as well as the vesicle-associated membrane-protein-associated proteins VAPA and VAPB interact with TRC40. Thus, our results provide new avenues to assess the essential role of TRC40 in metazoan organisms. This article has an associated First Person interview with the first author of the paper. Summary: A strategy to decipher which tail-anchored proteins do (as opposed to can or must) use the TRC pathway in intact cells generates a comprehensive list of human TRC40 clients.
Collapse
Affiliation(s)
- Javier Coy-Vergara
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen 37073, Germany
| | - Jhon Rivera-Monroy
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen 37073, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany.,Bioanalytics Group, Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen 37077, Germany
| | - Christof Lenz
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany.,Bioanalytics Group, Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen 37077, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen 37073, Germany .,Max Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| |
Collapse
|
15
|
Teresinski HJ, Gidda SK, Nguyen TND, Howard NJM, Porter BK, Grimberg N, Smith MD, Andrews DW, Dyer JM, Mullen RT. An RK/ST C-Terminal Motif is Required for Targeting of OEP7.2 and a Subset of Other Arabidopsis Tail-Anchored Proteins to the Plastid Outer Envelope Membrane. PLANT & CELL PHYSIOLOGY 2019; 60:516-537. [PMID: 30521026 DOI: 10.1093/pcp/pcy234] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 12/03/2018] [Indexed: 06/09/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of integral membrane proteins that possess a single C-terminal transmembrane domain and target post-translationally to the specific organelles at which they function. While significant advances have been made in recent years in elucidating the mechanisms and molecular targeting signals involved in the proper sorting of TA proteins, particularly to the endoplasmic reticulum and mitochondria, relatively little is known about the targeting of TA proteins to the plastid outer envelope. Here we show that several known or predicted plastid TA outer envelope proteins (OEPs) in Arabidopsis possess a C-terminal RK/ST sequence motif that serves as a conserved element of their plastid targeting signal. Evidence for this conclusion comes primarily from experiments with OEP7.2, which is a member of the Arabidopsis 7 kDa OEP family. We confirmed that OEP7.2 is localized to the plastid outer envelope and possesses a TA topology, and its C-terminal sequence (CTS), which includes the RK/ST motif, is essential for proper targeting to plastids. The CTS of OEP7.2 is functionally interchangeable with the CTSs of other TA OEPs that possess similar RK/ST motifs, but not with those that lack the motif. Further, a bioinformatics search based on a consensus sequence led to the identification of several new OEP TA proteins. Collectively, this study provides new insight into the mechanisms of TA protein sorting in plant cells, defines a new targeting signal element for a subset of TA OEPs and expands the number and repertoire of TA proteins at the plastid outer envelope.
Collapse
Affiliation(s)
- Howard J Teresinski
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Thuy N D Nguyen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Naomi J Marty Howard
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Brittany K Porter
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Nicholas Grimberg
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - David W Andrews
- Sunnybrook Research Institute and Departments of Biochemistry and Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - John M Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research Center, Maricopa, USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| |
Collapse
|
16
|
Abdelrehim A, Shaltiel L, Zhang L, Barenholz Y, High S, Harris LK. The use of tail-anchored protein chimeras to enhance liposomal cargo delivery. PLoS One 2019; 14:e0212701. [PMID: 30794671 PMCID: PMC6386398 DOI: 10.1371/journal.pone.0212701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/07/2019] [Indexed: 11/18/2022] Open
Abstract
Background Liposomes are employed as drug delivery vehicles offering a beneficial pharmacokinetic/distribution mechanism for in vivo therapeutics. Therapeutic liposomes can be designed to target specific cell types through the display of epitope-specific targeting peptides on their surface. The majority of peptides are currently attached by chemical modification of lipid constituents. Here we investigate an alternative and novel method of decorating liposomes with targeting ligand, using remotely and spontaneously inserting chimeric tail-anchored membrane (TA) proteins to drug loaded liposomes. Methods and results An artificial TA protein chimera containing the transmembrane domain from the spontaneously inserting TA protein cytochrome b5 (Cytb5) provided a robust membrane tether for the incorporation of three different targeting moieties into preformed liposomes. The moieties investigated were the transactivator of transcription (TAT) peptide, the EGF-receptor binding sequence GE11 and the placental and tumour homing ligand CCGKRK. In all cases, TA protein insertion neither significantly altered the size of the liposomes nor reduced drug loading. The efficacy of this novel targeted delivery system was investigated using two human cell lines, HeLa M and BeWo. Short term incubation with one ligand-modified TA chimera, incorporating the TAT peptide, significantly enhanced liposomal delivery of the encapsulated carboxyfluorescein reporter. Conclusion The Cytb5 TA was successfully employed as a membrane anchor for the incorporation of the desired peptide ligands into a liposomal drug delivery system, with minimal loss of cargo during insertion. This approach therefore provides a viable alternative to chemical conjugation and its potential to accommodate a wider range of targeting ligands may provide an opportunity for enhancing drug delivery.
Collapse
Affiliation(s)
- Abbi Abdelrehim
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | | | - Ling Zhang
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Yechezkel Barenholz
- Lipocure Ltd., Jerusalem, Israel
- Membrane and Liposome Research Lab, Hadassah Medical School of the Hebrew University, Jerusalem, Israel
| | - Stephen High
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Lynda K. Harris
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Maternal and Fetal Health Research Centre, Institute of Human Development, University of Manchester, Manchester, United Kingdom
- St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
- * E-mail:
| |
Collapse
|
17
|
Rada P, Makki A, Žárský V, Tachezy J. Targeting of tail-anchored proteins to Trichomonas vaginalis hydrogenosomes. Mol Microbiol 2019; 111:588-603. [PMID: 30506591 DOI: 10.1111/mmi.14175] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2018] [Indexed: 01/17/2023]
Abstract
Tail-anchored (TA) proteins are membrane proteins that are found in all domains of life. They consist of an N-terminal domain that performs various functions and a single transmembrane domain (TMD) near the C-terminus. In eukaryotes, TA proteins are targeted to the membranes of mitochondria, the endoplasmic reticulum (ER), peroxisomes and in plants, chloroplasts. The targeting of these proteins to their specific destinations correlates with the properties of the C-terminal domain, mainly the TMD hydrophobicity and the net charge of the flanking regions. Trichomonas vaginalis is a human parasite that has adapted to oxygen-poor environment. This adaptation is reflected by the presence of highly modified mitochondria (hydrogenosomes) and the absence of peroxisomes. The proteome of hydrogenosomes is considerably reduced; however, our bioinformatic analysis predicted 120 putative hydrogenosomal TA proteins. Seven proteins were selected to prove their localization. The elimination of the net positive charge in the C-tail of the hydrogenosomal TA4 protein resulted in its dual localization to hydrogenosomes and the ER, causing changes in ER morphology. Domain mutation and swap experiments with hydrogenosomal (TA4) and ER (TAPDI) proteins indicated that the general principles for specific targeting are conserved across eukaryotic lineages, including T. vaginalis; however, there are also significant lineage-specific differences.
Collapse
Affiliation(s)
- Petr Rada
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, Vestec, 25242, Czech Republic
| | - Abhijith Makki
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, Vestec, 25242, Czech Republic
| | - Vojtěch Žárský
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, Vestec, 25242, Czech Republic
| | - Jan Tachezy
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Průmyslová 595, Vestec, 25242, Czech Republic
| |
Collapse
|
18
|
Leznicki P, Natarajan J, Bader G, Spevak W, Schlattl A, Abdul Rehman SA, Pathak D, Weidlich S, Zoephel A, Bordone MC, Barbosa-Morais NL, Boehmelt G, Kulathu Y. Expansion of DUB functionality generated by alternative isoforms - USP35, a case study. J Cell Sci 2018; 131:jcs.212753. [PMID: 29685892 DOI: 10.1242/jcs.212753] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 04/01/2018] [Indexed: 12/12/2022] Open
Abstract
Protein ubiquitylation is a dynamic post-translational modification that can be reversed by deubiquitylating enzymes (DUBs). It is unclear how the small number (∼100) of DUBs present in mammalian cells regulate the thousands of different ubiquitylation events. Here, we analysed annotated transcripts of human DUBs and found ∼300 ribosome-associated transcripts annotated as protein coding, which thus increases the total number of DUBs. By using USP35, a poorly studied DUB, as a case study, we provide evidence that alternative isoforms contribute to the functional expansion of DUBs. We show that there are two different USP35 isoforms that localise to different intracellular compartments and have distinct functions. Our results reveal that isoform 1 is an anti-apoptotic factor that inhibits staurosporine- and TNF-related apoptosis-inducing ligand (TRAIL; also known as TNFSF10)-induced apoptosis. In contrast, USP35 isoform 2 is an integral membrane protein of the endoplasmic reticulum (ER) that is also present at lipid droplets. Manipulations of isoform 2 levels cause rapid ER stress, likely through deregulation of lipid homeostasis, and lead to cell death. Our work highlights how alternative isoforms provide functional expansion of DUBs and sets directions for future research.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Pawel Leznicki
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Jayaprakash Natarajan
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Gerd Bader
- Boehringer Ingelheim RCV GmbH & Co KG, Dr. Boehringer Gasse 5-11, 1120 Vienna, Austria
| | - Walter Spevak
- Boehringer Ingelheim RCV GmbH & Co KG, Dr. Boehringer Gasse 5-11, 1120 Vienna, Austria
| | - Andreas Schlattl
- Boehringer Ingelheim RCV GmbH & Co KG, Dr. Boehringer Gasse 5-11, 1120 Vienna, Austria
| | - Syed Arif Abdul Rehman
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Deepika Pathak
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Simone Weidlich
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Andreas Zoephel
- Boehringer Ingelheim RCV GmbH & Co KG, Dr. Boehringer Gasse 5-11, 1120 Vienna, Austria
| | - Marie C Bordone
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal
| | - Nuno L Barbosa-Morais
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal
| | - Guido Boehmelt
- Boehringer Ingelheim RCV GmbH & Co KG, Dr. Boehringer Gasse 5-11, 1120 Vienna, Austria
| | - Yogesh Kulathu
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| |
Collapse
|
19
|
Figueiredo Costa B, Cassella P, Colombo SF, Borgese N. Discrimination between the endoplasmic reticulum and mitochondria by spontaneously inserting tail‐anchored proteins. Traffic 2018; 19:182-197. [DOI: 10.1111/tra.12550] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 01/16/2023]
Affiliation(s)
- Bruna Figueiredo Costa
- CNR Institute of Neuroscience and BIOMETRA DepartmentUniversità degli Studi di Milano Milan Italy
| | - Patrizia Cassella
- CNR Institute of Neuroscience and BIOMETRA DepartmentUniversità degli Studi di Milano Milan Italy
| | | | | |
Collapse
|
20
|
Vitali DG, Sinzel M, Bulthuis EP, Kolb A, Zabel S, Mehlhorn DG, Costa BF, Farkas Á, Clancy A, Schuldiner M, Grefen C, Schwappach B, Borgese N, Rapaport D. The GET pathway can increase the risk of mitochondrial outer membrane proteins to be mistargeted to the ER. J Cell Sci 2018; 131:jcs.211110. [DOI: 10.1242/jcs.211110] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 04/10/2018] [Indexed: 01/23/2023] Open
Abstract
Tail-anchored (TA) proteins are anchored to their corresponding membrane via a single transmembrane segment (TMS) at their C-terminus. In yeast, the targeting of TA proteins to the endoplasmic reticulum (ER) can be mediated by the guided entry of TA proteins (GET) pathway, whereas it is not yet clear how mitochondrial TA proteins are targeted to their destination. It is widely observed that some mitochondrial outer membrane (OM) proteins are mistargeted to the ER when overexpressed or when their targeting signal is masked. However, the mechanism of this erroneous sorting is currently unknown. In this study, we demonstrate the involvement of the GET machinery in mistargeting of non-optimal mitochondrial OM proteins to the ER. These findings suggest that the GET machinery can, in principle, recognize and guide mitochondrial and non-canonical TA proteins. Hence, under normal conditions, an active mitochondrial targeting pathway must exist that dominates the kinetic competition against other pathways.
Collapse
Affiliation(s)
- Daniela G. Vitali
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Monika Sinzel
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Elianne P. Bulthuis
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Antonia Kolb
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Susanne Zabel
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Dietmar G. Mehlhorn
- Centre for Plant Molecular Biology, Developmental Genetics, University of Tübingen, Tübingen, Germany
| | | | - Ákos Farkas
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen 37073, Germany
| | - Anne Clancy
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen 37073, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Christopher Grefen
- Centre for Plant Molecular Biology, Developmental Genetics, University of Tübingen, Tübingen, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen 37073, Germany
| | - Nica Borgese
- Consiglio Nazionale delle Ricerche Institute of Neuroscience, Milan, Italy
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| |
Collapse
|
21
|
Daniele LL, Emran F, Lobo GP, Gaivin RJ, Perkins BD. Mutation of wrb, a Component of the Guided Entry of Tail-Anchored Protein Pathway, Disrupts Photoreceptor Synapse Structure and Function. Invest Ophthalmol Vis Sci 2017; 57:2942-54. [PMID: 27273592 PMCID: PMC4898200 DOI: 10.1167/iovs.15-18996] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Tail-anchored (TA) proteins contain a single hydrophobic domain at the C-terminus and are posttranslationally inserted into the ER membrane via the GET (guided entry of tail-anchored proteins) pathway. The role of the GET pathway in photoreceptors is unexplored. The goal of this study was to characterize the zebrafish pinball wizard mutant, which disrupts Wrb, a core component of the GET pathway. METHODS Electroretinography, optokinetic response measurements (OKR), immunohistochemistry, and electron microscopy analyses were employed to assess ribbon synapse function, protein expression, and ultrastructure in 5-day-old zebrafish larvae. Expression of wrb was investigated with real-time qRT-PCR and in situ hybridization. RESULTS Mutation of wrb abolished the OKR and greatly diminished the ERG b-wave, but not the a-wave. Ribeye and SV2 were partially mislocalized in both photoreceptors and hair cells of wrb mutants. Fewer contacts were seen between photoreceptors and bipolar cells in wrb-/- mutants. Expression of wrb was observed throughout the nervous system and Wrb localized to the ER and synaptic region of photoreceptors. Morpholino knockdown of the cytosolic ATPase trc40, which targets TA proteins to the ER, also diminished the OKR. Overexpression of wrb fully restored contrast sensitivity in mutants, while overexpression of mutant wrbR73A, which cannot bind Trc40, did not. CONCLUSIONS Proteins Wrb and Trc40 are required for synaptic transmission between photoreceptors and bipolar cells, indicating that TA protein insertion by the TRC pathway is a critical step in ribbon synapse assembly and function.
Collapse
Affiliation(s)
- Lauren L Daniele
- Department of Ophthalmic Research Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Farida Emran
- Centre for Research in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Glenn P Lobo
- Department of Ophthalmic Research Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Robert J Gaivin
- Department of Ophthalmic Research Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Brian D Perkins
- Department of Ophthalmic Research Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| |
Collapse
|
22
|
Padgett LR, Arrizabalaga G, Sullivan WJ. Targeting of tail-anchored membrane proteins to subcellular organelles in Toxoplasma gondii. Traffic 2017; 18:149-158. [PMID: 27991712 DOI: 10.1111/tra.12464] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 12/12/2016] [Accepted: 12/12/2016] [Indexed: 12/20/2022]
Abstract
Proper protein localization is essential for critical cellular processes, including vesicle-mediated transport and protein translocation. Tail-anchored (TA) proteins are integrated into organellar membranes via the C-terminus, orienting the N-terminus towards the cytosol. Localization of TA proteins occurs posttranslationally and is governed by the C-terminus, which contains the integral transmembrane domain (TMD) and targeting sequence. Targeting of TA proteins is dependent on the hydrophobicity of the TMD as well as the length and composition of flanking amino acid sequences. We previously identified an unusual homologue of elongator protein, Elp3, in the apicomplexan parasite Toxoplasma gondii as a TA protein targeting the outer mitochondrial membrane. We sought to gain further insight into TA proteins and their targeting mechanisms using this early-branching eukaryote as a model. Our bioinformatics analysis uncovered 59 predicted TA proteins in Toxoplasma, 9 of which were selected for follow-up analyses based on representative features. We identified novel TA proteins that traffic to specific organelles in Toxoplasma, including the parasite endoplasmic reticulum, mitochondrion, and Golgi apparatus. Domain swap experiments elucidated that targeting of TA proteins to these specific organelles was strongly influenced by the TMD sequence, including charge of the flanking C-terminal sequence.
Collapse
Affiliation(s)
- Leah R Padgett
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana
| | - William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana
| |
Collapse
|
23
|
Evidence for Amino Acid Snorkeling from a High-Resolution, In Vivo Analysis of Fis1 Tail-Anchor Insertion at the Mitochondrial Outer Membrane. Genetics 2016; 205:691-705. [PMID: 28007883 PMCID: PMC5289845 DOI: 10.1534/genetics.116.196428] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/12/2016] [Indexed: 01/03/2023] Open
Abstract
Proteins localized to mitochondria by a carboxyl-terminal tail anchor (TA) play roles in apoptosis, mitochondrial dynamics, and mitochondrial protein import. To reveal characteristics of TAs that may be important for mitochondrial targeting, we focused our attention upon the TA of the Saccharomyces cerevisiaeFis1 protein. Specifically, we generated a library of Fis1p TA variants fused to the Gal4 transcription factor, then, using next-generation sequencing, revealed which Fis1p TA mutations inhibited membrane insertion and allowed Gal4p activity in the nucleus. Prompted by our global analysis, we subsequently analyzed the ability of individual Fis1p TA mutants to localize to mitochondria. Our findings suggest that the membrane-associated domain of the Fis1p TA may be bipartite in nature, and we encountered evidence that the positively charged patch at the carboxyl terminus of Fis1p is required for both membrane insertion and organelle specificity. Furthermore, lengthening or shortening of the Fis1p TA by up to three amino acids did not inhibit mitochondrial targeting, arguing against a model in which TA length directs insertion of TAs to distinct organelles. Most importantly, positively charged residues were more acceptable at several positions within the membrane-associated domain of the Fis1p TA than negatively charged residues. These findings, emerging from the first high-resolution analysis of an organelle targeting sequence by deep mutational scanning, provide strong, in vivo evidence that lysine and arginine can “snorkel,” or become stably incorporated within a lipid bilayer by placing terminal charges of their side chains at the membrane interface.
Collapse
|
24
|
Rao M, Okreglak V, Chio US, Cho H, Walter P, Shan SO. Multiple selection filters ensure accurate tail-anchored membrane protein targeting. eLife 2016; 5. [PMID: 27925580 PMCID: PMC5214336 DOI: 10.7554/elife.21301] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/06/2016] [Indexed: 11/13/2022] Open
Abstract
Accurate protein localization is crucial to generate and maintain organization in all cells. Achieving accuracy is challenging, as the molecular signals that dictate a protein's cellular destination are often promiscuous. A salient example is the targeting of an essential class of tail-anchored (TA) proteins, whose sole defining feature is a transmembrane domain near their C-terminus. Here we show that the Guided Entry of Tail-anchored protein (GET) pathway selects TA proteins destined to the endoplasmic reticulum (ER) utilizing distinct molecular steps, including differential binding by the co-chaperone Sgt2 and kinetic proofreading after ATP hydrolysis by the targeting factor Get3. Further, the different steps select for distinct physicochemical features of the TA substrate. The use of multiple selection filters may be general to protein biogenesis pathways that must distinguish correct and incorrect substrates based on minor differences.
Collapse
Affiliation(s)
- Meera Rao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| | - Voytek Okreglak
- Howard Hughes Medical Institute, University of California, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, United States
| | - Un Seng Chio
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| | - Hyunju Cho
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| | - Peter Walter
- Howard Hughes Medical Institute, University of California, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, United States
| | - Shu-Ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, United States
| |
Collapse
|
25
|
Hawthorne JL, Mehta PR, Singh PP, Wong NQ, Quintero OA. Positively charged residues within the MYO19 MyMOMA domain are essential for proper localization of MYO19 to the mitochondrial outer membrane. Cytoskeleton (Hoboken) 2016; 73:286-299. [PMID: 27126804 DOI: 10.1002/cm.21305] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 11/06/2022]
Abstract
Myosins are well characterized molecular motors essential for intracellular transport. MYO19 copurifies with mitochondria, and can be released from mitochondrial membranes by high pH buffer, suggesting that positively-charged residues participate in interactions between MYO19 and mitochondria. The MYO19-specific mitochondria outer membrane association (MyMOMA) domain contains approximately 150 amino acids with a pI approximately 9 and is sufficient for localization to the mitochondrial outer membrane. The minimal sequence and specific residues involved in mitochondrial binding have not been identified. To address this, we generated GFP-MyMOMA truncations, establishing the boundaries for truncations based on sequence homology. We identified an 83-amino acid minimal binding region enriched with basic residues (pI ∼ 10.5). We sequentially replaced basic residues in this region with alanine, identifying residues R882 and K883 as essential for mitochondrial localization. Constructs containing the RK882-883AA mutation primarily localized with the endoplasmic reticulum (ER). To determine if ER-associated mutant MyMOMA domain and mitochondria-associated wild type MyMOMA display differences in kinetics of membrane interaction, we paired FRAP analysis with permeabilization activated reduction in fluorescence (PARF) analysis. Mitochondria-bound and ER-bound MYO19 constructs displayed slow dissociation from their target membrane when assayed by PARF; both constructs displayed exchange within their respective organelle networks. However, ER-bound mutant MYO19 displayed more rapid exchange within the ER network than did mitochondria-bound MYO19. Taken together these data indicate that the MyMOMA domain contains strong membrane-binding activity, and membrane targeting is mediated by a specific, basic region of the MYO19 tail with slow dissociation kinetics appropriate for its role(s) in mitochondrial network dynamics. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
| | | | - Pali P Singh
- Department of Biology, University of Richmond, VA 23173
| | - Nathan Q Wong
- Department of Biology, University of Richmond, VA 23173
| | | |
Collapse
|
26
|
Pfaff J, Rivera Monroy J, Jamieson C, Rajanala K, Vilardi F, Schwappach B, Kehlenbach RH. Emery-Dreifuss muscular dystrophy mutations impair TRC40-mediated targeting of emerin to the inner nuclear membrane. J Cell Sci 2015; 129:502-16. [PMID: 26675233 DOI: 10.1242/jcs.179333] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/14/2015] [Indexed: 11/20/2022] Open
Abstract
Emerin is a tail-anchored protein that is found predominantly at the inner nuclear membrane (INM), where it associates with components of the nuclear lamina. Mutations in the emerin gene cause Emery-Dreifuss muscular dystrophy (EDMD), an X-linked recessive disease. Here, we report that the TRC40/GET pathway for post-translational insertion of tail-anchored proteins into membranes is involved in emerin-trafficking. Using proximity ligation assays, we show that emerin interacts with TRC40 in situ. Emerin expressed in bacteria or in a cell-free lysate was inserted into microsomal membranes in an ATP- and TRC40-dependent manner. Dominant-negative fragments of the TRC40-receptor proteins WRB and CAML (also known as CAMLG) inhibited membrane insertion. A rapamycin-based dimerization assay revealed correct transport of wild-type emerin to the INM, whereas TRC40-binding, membrane integration and INM-targeting of emerin mutant proteins that occur in EDMD was disturbed. Our results suggest that the mode of membrane integration contributes to correct targeting of emerin to the INM.
Collapse
Affiliation(s)
- Janine Pfaff
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany
| | - Jhon Rivera Monroy
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany
| | - Cara Jamieson
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany
| | - Kalpana Rajanala
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany
| | - Fabio Vilardi
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany Max-Planck Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Humboldtallee 23, Göttingen 37073, Germany
| |
Collapse
|
27
|
Shneyer BI, Ušaj M, Henn A. Myo19 is an outer mitochondrial membrane motor and effector of starvation-induced filopodia. J Cell Sci 2015; 129:543-56. [PMID: 26659663 DOI: 10.1242/jcs.175349] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 12/05/2015] [Indexed: 12/13/2022] Open
Abstract
Mitochondria respond to environmental cues and stress conditions. Additionally, the disruption of the mitochondrial network dynamics and its distribution is implicated in a variety of neurodegenerative diseases. Here, we reveal a new function for Myo19 in mitochondrial dynamics and localization during the cellular response to glucose starvation. Ectopically expressed Myo19 localized with mitochondria to the tips of starvation-induced filopodia. Corollary to this, RNA interference (RNAi)-mediated knockdown of Myo19 diminished filopodia formation without evident effects on the mitochondrial network. We analyzed the Myo19-mitochondria interaction, and demonstrated that Myo19 is uniquely anchored to the outer mitochondrial membrane (OMM) through a 30-45-residue motif, indicating that Myo19 is a stably attached OMM molecular motor. Our work reveals a new function for Myo19 in mitochondrial positioning under stress.
Collapse
Affiliation(s)
- Boris I Shneyer
- Department of Biology, Technion Israel Institute of Technology, Haifa 3200003, Israel
| | - Marko Ušaj
- Department of Biology, Technion Israel Institute of Technology, Haifa 3200003, Israel
| | - Arnon Henn
- Department of Biology, Technion Israel Institute of Technology, Haifa 3200003, Israel
| |
Collapse
|
28
|
Gristick HB, Rome ME, Chartron JW, Rao M, Hess S, Shan SO, Clemons WM. Mechanism of Assembly of a Substrate Transfer Complex during Tail-anchored Protein Targeting. J Biol Chem 2015; 290:30006-17. [PMID: 26451041 PMCID: PMC4705998 DOI: 10.1074/jbc.m115.677328] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 10/02/2015] [Indexed: 11/06/2022] Open
Abstract
Tail-anchored (TA) proteins, defined as having a single transmembrane helix at their C terminus, are post-translationally targeted to the endoplasmic reticulum membrane by the guided entry of TA proteins (GET) pathway. In yeast, the handover of TA substrates is mediated by the heterotetrameric Get4/Get5 complex (Get4/5), which tethers the co-chaperone Sgt2 to the targeting factor, the Get3 ATPase. Binding of Get4/5 to Get3 is critical for efficient TA targeting; however, questions remain about the formation of the Get3·Get4/5 complex. Here we report crystal structures of a Get3·Get4/5 complex from Saccharomyces cerevisiae at 2.8 and 6.0 Å that reveal a novel interface between Get3 and Get4 dominated by electrostatic interactions. Kinetic and mutational analyses strongly suggest that these structures represent an on-pathway intermediate that rapidly assembles and then rearranges to the final Get3·Get4/5 complex. Furthermore, we provide evidence that the Get3·Get4/5 complex is dominated by a single Get4/5 heterotetramer bound to one monomer of a Get3 dimer, uncovering an intriguing asymmetry in the Get4/5 heterotetramer upon Get3 binding. Ultrafast diffusion-limited electrostatically driven Get3·Get4/5 association enables Get4/5 to rapidly sample and capture Get3 at different stages of the GET pathway.
Collapse
Affiliation(s)
| | - Michael E Rome
- From the Division of Chemistry and Chemical Engineering and
| | | | - Meera Rao
- From the Division of Chemistry and Chemical Engineering and
| | - Sonja Hess
- The Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, California 91125
| | - Shu-ou Shan
- From the Division of Chemistry and Chemical Engineering and
| | | |
Collapse
|
29
|
Fueller J, Egorov MV, Walther KA, Sabet O, Mallah J, Grabenbauer M, Kinkhabwala A. Subcellular Partitioning of Protein Tyrosine Phosphatase 1B to the Endoplasmic Reticulum and Mitochondria Depends Sensitively on the Composition of Its Tail Anchor. PLoS One 2015; 10:e0139429. [PMID: 26431424 PMCID: PMC4592070 DOI: 10.1371/journal.pone.0139429] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 09/14/2015] [Indexed: 01/15/2023] Open
Abstract
The canonical protein tyrosine phosphatase PTP1B is an important regulator of diverse cellular signaling networks. PTP1B has long been thought to exert its influence solely from its perch on the endoplasmic reticulum (ER); however, an additional subpopulation of PTP1B has recently been detected in mitochondria extracted from rat brain tissue. Here, we show that PTP1B’s mitochondrial localization is general (observed across diverse mammalian cell lines) and sensitively dependent on the transmembrane domain length, C-terminal charge and hydropathy of its short (≤35 amino acid) tail anchor. Our electron microscopy of specific DAB precipitation revealed that PTP1B localizes via its tail anchor to the outer mitochondrial membrane (OMM), with fluorescence lifetime imaging microscopy establishing that this OMM pool contributes to the previously reported cytoplasmic interaction of PTP1B with endocytosed epidermal growth factor receptor. We additionally examined the mechanism of PTP1B’s insertion into the ER membrane through heterologous expression of PTP1B’s tail anchor in wild-type yeast and yeast mutants of major conserved ER insertion pathways: In none of these yeast strains was ER targeting significantly impeded, providing in vivo support for the hypothesis of spontaneous membrane insertion (as previously demonstrated in vitro). Further functional elucidation of the newly recognized mitochondrial pool of PTP1B will likely be important for understanding its complex roles in cellular responses to external stimuli, cell proliferation and diseased states.
Collapse
Affiliation(s)
- Julia Fueller
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Mikhail V. Egorov
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- Institute of Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120, Heidelberg, Germany
| | - Kirstin A. Walther
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Ola Sabet
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Jana Mallah
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
| | - Markus Grabenbauer
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- Institute of Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120, Heidelberg, Germany
| | - Ali Kinkhabwala
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany
- * E-mail:
| |
Collapse
|
30
|
Yuan W, Veenhuis M, van der Klei IJ. The birth of yeast peroxisomes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:902-10. [PMID: 26367802 DOI: 10.1016/j.bbamcr.2015.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 11/25/2022]
Abstract
This contribution describes the phenotypic differences of yeast peroxisome-deficient mutants (pex mutants). In some cases different phenotypes were reported for yeast mutants deleted in the same PEX gene. These differences are most likely related to the marker proteins and methods used to detect peroxisomal remnants. This is especially evident for pex3 and pex19 mutants, where the localization of receptor docking proteins (Pex13, Pex14) resulted in the identification of peroxisomal membrane remnants, which do not contain other peroxisomal membrane proteins, such as the ring proteins Pex2, Pex10 and Pex12. These structures in pex3 and pex19 cells are the template for peroxisome formation upon introduction of the missing gene. Taken together, these data suggest that in all yeast pex mutants analyzed so far peroxisomes are not formed de novo but use membrane remnant structures as a template for peroxisome formation upon reintroduction of the missing gene. The relevance of this model for peroxisomal membrane protein and lipid sorting to peroxisomes is discussed.
Collapse
Affiliation(s)
- Wei Yuan
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands
| | - Marten Veenhuis
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands
| | - Ida J van der Klei
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands.
| |
Collapse
|
31
|
Cui XA, Zhang H, Ilan L, Liu AX, Kharchuk I, Palazzo AF. mRNA encoding Sec61β, a tail-anchored protein, is localized on the endoplasmic reticulum. J Cell Sci 2015; 128:3398-410. [PMID: 26272916 PMCID: PMC4582399 DOI: 10.1242/jcs.168583] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 08/04/2015] [Indexed: 12/30/2022] Open
Abstract
Although one pathway for the post-translational targeting of tail-anchored proteins to the endoplasmic reticulum (ER) has been well defined, it is unclear whether additional pathways exist. Here, we provide evidence that a subset of mRNAs encoding tail-anchored proteins, including Sec61β and nesprin-2, is partially localized to the surface of the ER in mammalian cells. In particular, Sec61b mRNA can be targeted to, and later maintained on, the ER using both translation-dependent and -independent mechanisms. Our data suggests that this process is independent of p180 (also known as RRBP1), a known mRNA receptor on the ER, and the transmembrane domain recognition complex (TRC) pathway components, TRC40 (also known as ASNA1) and BAT3 (also known as BAG6). In addition, our data indicates that Sec61b mRNA might access translocon-bound ribosomes. Our results show that certain tail-anchored proteins are likely to be synthesized directly on the ER, and this facilitates their membrane insertion. Thus, it is clear that mammalian cells utilize multiple mechanisms to ensure efficient targeting of tail-anchored proteins to the surface of the ER. Highlighted Article: The mRNA encoding certain tail-anchored proteins is directly localized to the surface of the endoplasmic reticulum, facilitating the insertion of newly synthesized proteins into the membrane.
Collapse
Affiliation(s)
- Xianying A Cui
- University of Toronto, Department of Biochemistry, 1 King's College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Hui Zhang
- University of Toronto, Department of Biochemistry, 1 King's College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Lena Ilan
- University of Toronto, Department of Biochemistry, 1 King's College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Ai Xin Liu
- University of Toronto, Department of Biochemistry, 1 King's College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Iryna Kharchuk
- University of Toronto, Department of Biochemistry, 1 King's College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| | - Alexander F Palazzo
- University of Toronto, Department of Biochemistry, 1 King's College Circle, MSB Room 5336, Toronto, ON, M5S 1A8, Canada
| |
Collapse
|
32
|
Sergeev GV, Gilep AA, Usanov SA. The role of cytochrome b5 structural domains in interaction with cytochromes P450. BIOCHEMISTRY (MOSCOW) 2015; 79:406-16. [PMID: 24954591 DOI: 10.1134/s0006297914050046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To understand the role of the structural elements of cytochrome b5 in its interaction with cytochrome P450 and the catalysis performed by this heme protein, we carried out comparative structural and functional analysis of the two major mammalian forms of membrane-bound cytochrome b5 - microsomal and mitochondrial, designed chimeric forms of the heme proteins in which the hydrophilic domain of one heme protein is replaced by the hydrophilic domain of another one, and investigated the effect of the highly purified native and chimeric heme proteins on the enzymatic activity of recombinant cytochromes P4503A4 and P45017A1 (CYP3A4 and CYP17A1). We show that the presence of a hydrophobic domain in the structure of cytochrome b5 is necessary for its effective interaction with its redox partners, while the nature of the hydrophobic domain has no significant effect on the ability of cytochrome b5 to stimulate the activity of cytochrome P450-catalyzed reactions. Thus, the functional properties of cytochrome b5 are mainly determined by the structure of the heme-binding domain.
Collapse
Affiliation(s)
- G V Sergeev
- Institute of Bioorganic Chemistry, Academy of Sciences of Belarus, Minsk, 220141, Belarus.
| | | | | |
Collapse
|
33
|
The mammalian molybdenum enzymes of mARC. J Biol Inorg Chem 2014; 20:265-75. [PMID: 25425164 DOI: 10.1007/s00775-014-1216-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 11/11/2014] [Indexed: 01/14/2023]
Abstract
The "mitochondrial amidoxime reducing component" (mARC) is the most recently discovered molybdenum-containing enzyme in mammals. All mammalian genomes studied to date contain two mARC genes: MARC1 and MARC2. The proteins encoded by these genes are mARC-1 and mARC-2 and represent the simplest form of eukaryotic molybdenum enzymes, only binding the molybdenum cofactor. In the presence of NADH, mARC proteins exert N-reductive activity together with the two electron transport proteins cytochrome b5 type B and NADH cytochrome b5 reductase. This enzyme system is capable of reducing a great variety of N-hydroxylated substrates. It plays a decisive role in the activation of prodrugs containing an amidoxime structure, and in detoxification pathways, e.g., of N-hydroxylated purine and pyrimidine bases. It belongs to a group of drug metabolism enzymes, in particular as a counterpart of P450 formed N-oxygenated metabolites. Its physiological relevance, on the other hand, is largely unknown. The aim of this article is to summarize our current knowledge of these proteins with a special focus on the mammalian enzymes and their N-reductive activity.
Collapse
|
34
|
Structural and functional characterization of ybr137wp implicates its involvement in the targeting of tail-anchored proteins to membranes. Mol Cell Biol 2014; 34:4500-12. [PMID: 25288638 DOI: 10.1128/mcb.00697-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nearly 5% of membrane proteins are guided to nuclear, endoplasmic reticulum (ER), mitochondrial, Golgi, or peroxisome membranes by their C-terminal transmembrane domain and are classified as tail-anchored (TA) membrane proteins. In Saccharomyces cerevisiae, the guided entry of TA protein (GET) pathway has been shown to function in the delivery of TA proteins to the ER. The sorting complex for this pathway is comprised of Sgt2, Get4, and Get5 and facilitates the loading of nascent tail-anchored proteins onto the Get3 ATPase. Multiple pulldown assays also indicated that Ybr137wp associates with this complex in vivo. Here, we report a 2.8-Å-resolution crystal structure for Ybr137wp from Saccharomyces cerevisiae. The protein is a decamer in the crystal and also in solution, as observed by size exclusion chromatography and analytical ultracentrifugation. In addition, isothermal titration calorimetry indicated that the C-terminal acidic motif of Ybr137wp interacts with the tetratricopeptide repeat (TPR) domain of Sgt2. Moreover, an in vivo study demonstrated that Ybr137wp is induced in yeast exiting the log phase and ameliorates the defect of TA protein delivery and cell viability derived by the impaired GET system under starvation conditions. Therefore, this study suggests a possible role for Ybr137wp related to targeting of tail-anchored proteins.
Collapse
|
35
|
Gristick HB, Rao M, Chartron JW, Rome ME, Shan SO, Clemons WM. Crystal structure of ATP-bound Get3-Get4-Get5 complex reveals regulation of Get3 by Get4. Nat Struct Mol Biol 2014; 21:437-42. [PMID: 24727835 PMCID: PMC4386898 DOI: 10.1038/nsmb.2813] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 03/24/2014] [Indexed: 11/16/2022]
Abstract
Correct localization of membrane proteins is essential to all cells. Chaperone cascades coordinate the capture and handover of substrate proteins from the ribosomes to the target membranes, yet the mechanistic and structural details of these processes remain unclear. Here we investigate the conserved GET pathway, in which the Get4-Get5 complex mediates the handover of tail-anchor (TA) substrates from the cochaperone Sgt2 to the Get3 ATPase, the central targeting factor. We present a crystal structure of a yeast Get3-Get4-Get5 complex in an ATP-bound state and show how Get4 primes Get3 by promoting the optimal configuration for substrate capture. Structure-guided biochemical analyses demonstrate that Get4-mediated regulation of ATP hydrolysis by Get3 is essential to efficient TA-protein targeting. Analogous regulation of other chaperones or targeting factors could provide a general mechanism for ensuring effective substrate capture during protein biogenesis.
Collapse
Affiliation(s)
- Harry B. Gristick
- Division of Chemistry and Chemical Engineering, California Institute of Technology, CA, USA
| | - Meera Rao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, CA, USA
| | - Justin W. Chartron
- Division of Chemistry and Chemical Engineering, California Institute of Technology, CA, USA
| | - Michael E. Rome
- Division of Chemistry and Chemical Engineering, California Institute of Technology, CA, USA
| | - Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, CA, USA
| | - William M. Clemons
- Division of Chemistry and Chemical Engineering, California Institute of Technology, CA, USA
| |
Collapse
|
36
|
Fossati M, Borgese N, Colombo SF, Francolini M. Visualization of endoplasmic reticulum subdomains in cultured cells. J Vis Exp 2014:e50985. [PMID: 24637314 DOI: 10.3791/50985] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The lipids and proteins in eukaryotic cells are continuously exchanged between cell compartments, although these retain their distinctive composition and functions despite the intense interorganelle molecular traffic. The techniques described in this paper are powerful means of studying protein and lipid mobility and trafficking in vivo and in their physiological environment. Fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) are widely used live-cell imaging techniques for studying intracellular trafficking through the exo-endocytic pathway, the continuity between organelles or subcompartments, the formation of protein complexes, and protein localization in lipid microdomains, all of which can be observed under physiological and pathological conditions. The limitations of these approaches are mainly due to the use of fluorescent fusion proteins, and their potential drawbacks include artifactual over-expression in cells and the possibility of differences in the folding and localization of tagged and native proteins. Finally, as the limit of resolution of optical microscopy (about 200 nm) does not allow investigation of the fine structure of the ER or the specific subcompartments that can originate in cells under stress (i.e. hypoxia, drug administration, the over-expression of transmembrane ER resident proteins) or under pathological conditions, we combine live-cell imaging of cultured transfected cells with ultrastructural analyses based on transmission electron microscopy.
Collapse
Affiliation(s)
- Matteo Fossati
- Fondazione Filarete; Department of Biotechnology and Translational Medicine, University of Milan; Neuroscience Institute, National Research Council (CNR)
| | - Nica Borgese
- Department of Biotechnology and Translational Medicine, University of Milan; Neuroscience Institute, National Research Council (CNR); Department of Health Science, "Magna Graecia" University of Catanzaro
| | - Sara Francesca Colombo
- Department of Biotechnology and Translational Medicine, University of Milan; Neuroscience Institute, National Research Council (CNR)
| | - Maura Francolini
- Fondazione Filarete; Department of Biotechnology and Translational Medicine, University of Milan;
| |
Collapse
|
37
|
Casellato A, Rossi Paccani S, Barrile R, Bossi F, Ciucchi L, Codolo G, Pizza M, Aricò B, de Bernard M. The C2 fragment from Neisseria meningitidis antigen NHBA increases endothelial permeability by destabilizing adherens junctions. Cell Microbiol 2014; 16:925-37. [PMID: 24397470 DOI: 10.1111/cmi.12250] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 11/29/2013] [Accepted: 12/05/2013] [Indexed: 12/13/2022]
Abstract
Neisseria meningitidis is a human pathogen that can cause fatal sepsis and meningitis once it reaches the blood stream and the nervous system. Here we demonstrate that a fragment, released upon proteolysis of the surface-exposed protein Neisserial Heparin Binding Antigen (NHBA), by the bacterial protease NalP, alters the endothelial permeability by inducing the internalization of the adherens junction protein VE-cadherin. We found that C2 rapidly accumulates in mitochondria where it induces the production of reactive oxygen species: the latter are required for the phosphorylation of the junctional protein and for its internalization that, in turn, is responsible for the endothelial leakage. Our data support the notion that the NHBA-derived fragment C2 might contribute to the extensive vascular leakage typically associated with meningococcal sepsis.
Collapse
|
38
|
Marty NJ, Teresinski HJ, Hwang YT, Clendening EA, Gidda SK, Sliwinska E, Zhang D, Miernyk JA, Brito GC, Andrews DW, Dyer JM, Mullen RT. New insights into the targeting of a subset of tail-anchored proteins to the outer mitochondrial membrane. FRONTIERS IN PLANT SCIENCE 2014; 5:426. [PMID: 25237314 PMCID: PMC4154396 DOI: 10.3389/fpls.2014.00426] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/12/2014] [Indexed: 05/21/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of functionally diverse membrane proteins defined by their single C-terminal membrane-spanning domain and their ability to insert post-translationally into specific organelles with an Ncytoplasm-Corganelle interior orientation. The molecular mechanisms by which TA proteins are sorted to the proper organelles are not well-understood. Herein we present results indicating that a dibasic targeting motif (i.e., -R-R/K/H-X({X≠E})) identified previously in the C terminus of the mitochondrial isoform of the TA protein cytochrome b 5, also exists in many other A. thaliana outer mitochondrial membrane (OMM)-TA proteins. This motif is conspicuously absent, however, in all but one of the TA protein subunits of the translocon at the outer membrane of mitochondria (TOM), suggesting that these two groups of proteins utilize distinct biogenetic pathways. Consistent with this premise, we show that the TA sequences of the dibasic-containing proteins are both necessary and sufficient for targeting to mitochondria, and are interchangeable, while the TA regions of TOM proteins lacking a dibasic motif are necessary, but not sufficient for localization, and cannot be functionally exchanged. We also present results from a comprehensive mutational analysis of the dibasic motif and surrounding sequences that not only greatly expands the functional definition and context-dependent properties of this targeting signal, but also led to the identification of other novel putative OMM-TA proteins. Collectively, these results provide important insight to the complexity of the targeting pathways involved in the biogenesis of OMM-TA proteins and help define a consensus targeting motif that is utilized by at least a subset of these proteins.
Collapse
Affiliation(s)
- Naomi J. Marty
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Howard J. Teresinski
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Eric A. Clendening
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Elwira Sliwinska
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- Department of Plant Genetics, Physiology and Biotechnology, University of Technology and Life Sciences in BydgoszczBydgoszcz, Poland
| | - Daiyuan Zhang
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Ján A. Miernyk
- United States Department of Agriculture, Agricultural Research Service, Plant Genetics Research Unit, University of MissouriColumbia, MO, USA
| | - Glauber C. Brito
- Instituto do Cancer do Estado de Sao Paulo, Fundacao Faculdade de Medicina, Universidade de Sao PauloSao Paulo, Brazil
| | - David W. Andrews
- Sunnybrook Research Institute and Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - John M. Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- *Correspondence: Robert T. Mullen, Department of Molecular and Cellular, Biology, University of Guelph, Room 4470 Science Complex, 488 Gordon Street, Guelph, ON N1G 2W1, Canada e-mail:
| |
Collapse
|
39
|
Tomasello MF, Guarino F, Reina S, Messina A, De Pinto V. The voltage-dependent anion selective channel 1 (VDAC1) topography in the mitochondrial outer membrane as detected in intact cell. PLoS One 2013; 8:e81522. [PMID: 24324700 PMCID: PMC3855671 DOI: 10.1371/journal.pone.0081522] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 10/14/2013] [Indexed: 12/31/2022] Open
Abstract
Voltage-Dependent Anion selective Channel maintains the permeability of the outer mitochondrial membrane and is relevant in bioenergetic metabolism and apoptosis. The structure of the protein was shown to be a β-barrel formed by 19 strands. The topology or sideness of the pore has been predicted with various approaches but a general consensus was never reached. This is an important issue since VDAC is considered receptor of Hexokinase and Bcl-2. We fused at VDAC1 C-terminus two tags separated by a caspase cleavage site. Activation in cellulo of caspases was used to eventually separate the two reporters. This experiment did not require the isolation of mitochondria and limited the possibility of outer membrane rupture due to similar procedures. Our results show that the C-terminus end of VDAC faces the mitochondrial inter-membrane space.
Collapse
Affiliation(s)
- Marianna F. Tomasello
- Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, and National Institute for Biomembranes and Biosystems, Section of Catania, Catania, Italy
| | - Francesca Guarino
- Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, and National Institute for Biomembranes and Biosystems, Section of Catania, Catania, Italy
| | - Simona Reina
- Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, and National Institute for Biomembranes and Biosystems, Section of Catania, Catania, Italy
| | - Angela Messina
- Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, and National Institute for Biomembranes and Biosystems, Section of Catania, Catania, Italy
| | - Vito De Pinto
- Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, and National Institute for Biomembranes and Biosystems, Section of Catania, Catania, Italy
- * E-mail:
| |
Collapse
|
40
|
Yagita Y, Hiromasa T, Fujiki Y. Tail-anchored PEX26 targets peroxisomes via a PEX19-dependent and TRC40-independent class I pathway. ACTA ACUST UNITED AC 2013; 200:651-66. [PMID: 23460677 PMCID: PMC3587837 DOI: 10.1083/jcb.201211077] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tail-anchored (TA) proteins are anchored into cellular membranes by a single transmembrane domain (TMD) close to the C terminus. Although the targeting of TA proteins to peroxisomes is dependent on PEX19, the mechanistic details of PEX19-dependent targeting and the signal that directs TA proteins to peroxisomes have remained elusive, particularly in mammals. The present study shows that PEX19 formed a complex with the peroxisomal TA protein PEX26 in the cytosol and translocated it directly to peroxisomes by interacting with the peroxisomal membrane protein PEX3. Unlike in yeast, the adenosine triphosphatase TRC40, which delivers TA proteins to the endoplasmic reticulum, was dispensable for the peroxisomal targeting of PEX26. Moreover, the basic amino acids within the luminal domain of PEX26 were essential for binding to PEX19 and thereby for peroxisomal targeting. Finally, our results suggest that a TMD that escapes capture by TRC40 and is followed by a highly basic luminal domain directs TA proteins to peroxisomes via the PEX19-dependent route.
Collapse
Affiliation(s)
- Yuichi Yagita
- Graduate School of Systems Life Sciences, Faculty of Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan
| | | | | |
Collapse
|
41
|
Schweiger R, Müller NC, Schmitt MJ, Soll J, Schwenkert S. AtTPR7 is a chaperone-docking protein of the Sec translocon in Arabidopsis. J Cell Sci 2012; 125:5196-207. [PMID: 22899711 DOI: 10.1242/jcs.111054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Chaperone-assisted sorting of post-translationally imported proteins is a general mechanism among all eukaryotic organisms. Interaction of some preproteins with the organellar membranes is mediated by chaperones, which are recognised by membrane-bound tetratricopeptide repeat (TPR) domain containing proteins. We have characterised AtTPR7 as an endoplasmic reticulum protein in plants and propose a potential function for AtTPR7 in post-translational protein import. Our data demonstrate that AtTPR7 interacts with the heat shock proteins HSP90 and HSP70 via a cytosol-exposed TPR domain. We further show by in vitro and in vivo experiments that AtTPR7 is associated with the Arabidopsis Sec63 homologue, AtERdj2. Interestingly, AtTPR7 can functionally complement a Δsec71 yeast mutant that is impaired in post-translational protein transport. These data strongly suggest that AtTPR7 not only has a role in chaperone binding but also in post-translational protein import into the endoplasmic reticulum, pointing to a general mechanism of chaperone-mediated post-translational sorting between the endoplasmic reticulum, mitochondria and chloroplasts in plant cells.
Collapse
Affiliation(s)
- Regina Schweiger
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Großhaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany
| | | | | | | | | |
Collapse
|
42
|
Williamson CD, DeBiasi RL, Colberg-Poley AM. Viral product trafficking to mitochondria, mechanisms and roles in pathogenesis. Infect Disord Drug Targets 2012; 12:18-37. [PMID: 22034933 PMCID: PMC4435936 DOI: 10.2174/187152612798994948] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 04/21/2011] [Accepted: 05/02/2011] [Indexed: 05/31/2023]
Abstract
A wide variety of viruses cause significant morbidity and mortality in humans. However, targeted antiviral therapies have been developed for only a subset of these viruses, with the majority of currently licensed antiviral drugs targeting viral entry, replication or exit steps during the viral life cycle. Due to increasing emergence of antiviral drug resistant viruses, the isolation of multiple viral subtypes, and toxicities of existing therapies, there remains an urgent need for the timely development of novel antiviral agents, including those targeting host factors essential for viral replication. This review summarizes viral products that target mitochondria and their effects on common mitochondria regulated pathways. These viral products and the mitochondrial pathways affected by them provide potential novel targets for the rational design of antiviral drugs. Viral products alter oxidative balance, mitochondrial permeability transition pore, mitochondrial membrane potential, electron transport and energy production. Moreover, viruses may cause the Warburg Effect, in which metabolism is reprogrammed to aerobic glycolysis as the main source of energy. Finally, viral products affect proapoptotic and antiapoptotic signaling, as well as mitochondrial innate immune signaling. Because of their importance for the generation of metabolic intermediates and energy as well as cell survival, mitochondrial pathways are targeted by multiple independent viral products. Structural modifications of existing drugs targeted to mitochondrial pathways may lead to the development of novel antiviral drugs with improved efficacy and reduced toxicity.
Collapse
Affiliation(s)
- Chad D. Williamson
- Center for Cancer and Immunology Research, Children’s National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010
| | - Roberta L. DeBiasi
- Center for Cancer and Immunology Research, Children’s National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010
- Division of Pediatric Infectious Diseases, Children’s National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010
- Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Washington DC 20037 Tel. 202-476-3984 FAX 202-476-3929
| | - Anamaris M. Colberg-Poley
- Center for Cancer and Immunology Research, Children’s National Medical Center, 111 Michigan Avenue, NW, Washington, DC 20010
- Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Washington DC 20037 Tel. 202-476-3984 FAX 202-476-3929
- Department of Biochemistry and Molecular Biology, George Washington University School of Medicine and Health Sciences, Washington DC 20037 Tel. 202-476-3984 FAX 202-476-3929
| |
Collapse
|
43
|
Kriechbaumer V, Abell BM. Chloroplast envelope protein targeting fidelity is independent of cytosolic components in dual organelle assays. FRONTIERS IN PLANT SCIENCE 2012; 3:148. [PMID: 22783268 PMCID: PMC3384937 DOI: 10.3389/fpls.2012.00148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/14/2012] [Indexed: 05/22/2023]
Abstract
The general mechanisms of intracellular protein targeting are well established, and depend on a targeting sequence in the protein, which is recognized by a targeting factor. Once a membrane protein is delivered to the correct organelle its targeting sequence can be recognized by receptors and a translocase, leading to membrane insertion. However, the relative contribution of each step for generating fidelity and efficiency of the overall process has not been systematically addressed. Here, we use tail-anchored (TA) membrane proteins in cell-free competitive targeting assays to chloroplasts to show that targeting can occur efficiently and with high fidelity in the absence of all cytosolic components, suggesting that chloroplast envelope protein targeting is primarily dependent on events at the outer envelope. Efficiency of targeting was increased by the addition of complete cytosol, and by Hsp70 or Hsp90, depending on the protein, but none of these cytosolic components influenced the fidelity of targeting. Our results suggest that the main role of targeting factors in chloroplast localization is to increase targeting efficiency by maintaining recognition competency at the outer envelope.
Collapse
Affiliation(s)
| | - Ben M. Abell
- *Correspondence: Ben M. Abell, Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK. e-mail:
| |
Collapse
|
44
|
A micropreparation of mitochondria from cells using magnetic beads with immunoaffinity. Anal Biochem 2011; 421:219-26. [PMID: 22178913 DOI: 10.1016/j.ab.2011.11.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 11/13/2011] [Accepted: 11/15/2011] [Indexed: 11/22/2022]
Abstract
Mitochondrial preparation is a key technique in the study of mitochondria. Growing evidence has demonstrated that mitochondrial proteins are tissue or cell type dependent. Locating the proteins in the global presence of mitochondrial membranes is a primary consideration in adopting antibodies for affinity enrichment of mitochondria on a micro scale. Two proteins located on the outer membrane of mitochondria, cytochrome b5 type B (CYB5B) and synaptojanin-2-binding protein (SYNJ2BP), were selected as candidates based on a survey of databases and the literature. The polyclonal antibodies against the truncated CYB5B and SYNJ2BP exhibited specific recognition to mitochondria and wider sensitivity to several tested mouse tissues and cell lines, whereas the antibody 22-kDa translocase of the outer mitochondrial membrane (TOM22) nearly missed detection of mitochondria in the liver and responded minimally to mitochondria from H9C2 and L-02 cells. Through the affinity enrichment for cellular mitochondria using magnetic beads coated with anti-CYB5B or anti-SYNJ2BP, we found that the anti-CYB5B beads could enrich mitochondria more efficiently even on a scale of 10,000 cultured cells. For the integrity and protein components, the enriched mitochondria on anti-CYB5B were carefully examined and were accepted in further functional study. We propose that an anti-CYB5B immunomagnetic approach is feasible in the micropreparation of mitochondria from cultured cells.
Collapse
|
45
|
Shani N, Shinder V, Zipori D. Mitochondria as a sequestration site for incomplete TCRβ peptides: the TCRβ transmembrane domain is a sufficient mitochondrial targeting signal. Mol Immunol 2011; 49:239-52. [PMID: 21943707 DOI: 10.1016/j.molimm.2011.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 08/23/2011] [Accepted: 08/25/2011] [Indexed: 11/26/2022]
Abstract
The existence of incomplete T cell receptor (TCR) mRNA forms, including germline transcripts and products of unfruitful TCR rearrangements, has long been known. However, it is unclear whether these molecules are functional. We have previously shown that T cells also contain truncated TCRβ peptides that lack the N-terminal part and contain C-terminus sequences. These partial forms of TCRβ, target the mitochondrion and induce apoptosis, exhibiting a novel mode of TCR mediated cell death. Here we aimed at analyzing the minimal TCR sequences that direct the peptide to the mitochondrion. It is shown that truncated TCRβ, targets mitochondria and induces mitochondrial perinuclear clustering, in both monkey COS-7 and human 293 cells. These phenomena are mediated by the C-terminus of the molecule. Whereas the positively charged amino acids flanking the transmembrane domain (TMD) of TCRβ are beneficial for this process, they are not essential. Indeed, the isolated TMD of TCRβ serves as a sufficient mitochondrial targeting sequence. These results indicate that any given partial form of TCRβ, that contains the TMD, is bound to be sequestered by the mitochondrion. This may assure that incomplete TCR forms would not interfere with correct TCR complex formation.
Collapse
Affiliation(s)
- Nir Shani
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | |
Collapse
|
46
|
Havemeyer A, Lang J, Clement B. The fourth mammalian molybdenum enzyme mARC: current state of research. Drug Metab Rev 2011; 43:524-39. [DOI: 10.3109/03602532.2011.608682] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
47
|
Abstract
TA (tail-anchored) proteins utilize distinct biosynthetic pathways, including TRC40 (transmembrane domain recognition complex of 40 kDa)-mediated, chaperone-dependent and/or unassisted routes to the ER (endoplasmic reticulum) membrane. We have addressed the flexibility of cytosolic components participating in these pathways, and explored the thermodynamic constraints of their membrane insertion, by exploiting recombinant forms of Sec61β and Cytb5 (cytochrome b5) bearing covalent modifications within their TA region. In both cases, efficient membrane insertion relied on cytosolic factors capable of accommodating a surprising range of covalent modifications to the TA region. For Sec61β, we found that both SGTA (small glutamine-rich tetratricopeptide repeat-containing protein α) and TRC40 can bind this substrate with a singly PEGylated TA region. However, by introducing two PEG [poly(ethylene glycol)] moieties, TRC40 binding can be prevented, resulting in a block of subsequent membrane integration. Although TRC40 can bind Sec61β polypeptides singly PEGylated at different locations, membrane insertion is more sensitive to the precise location of PEG attachment. Modelling and experimentation indicate that this post-TRC40 effect results from an increased energetic cost of inserting different PEGylated TA regions into the lipid bilayer. We therefore propose that the membrane integration of TA proteins delivered via TRC40 is strongly dependent upon underlying thermodynamics, and speculate that their insertion is via a phospholipid-mediated process.
Collapse
|
48
|
Increased expression of the tail-anchored membrane protein SLMAP in adipose tissue from type 2 Tally Ho diabetic mice. EXPERIMENTAL DIABETES RESEARCH 2011; 2011:421982. [PMID: 21785580 PMCID: PMC3137969 DOI: 10.1155/2011/421982] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 05/05/2011] [Indexed: 11/17/2022]
Abstract
The tail-anchored membrane protein, sarcolemmal membrane associated protein (SLMAP) is encoded to a single gene that maps to the chromosome 3p14 region and has also been reported in certain diabetic populations. Our previous studies with db/db mice shown that a deregulation of SLMAP expression plays an important role in type 2 diabetes. Male Tally Ho mice were bred to present with either normoglycemia (NG) or hyperglycemia (HG). Abdominal adipose tissue from male Tally Ho mice of the HG group was found to have a significantly lower expression of the membrane associated glucose transporter-4 (GLUT-4) and higher expression of SLMAP compared to tissue from NG mice. There were 3 isoforms expressed in the abdominal adipose tissue, but only 45 kDa isoform of SLMAP was associated with the GLUT-4 revealed by immunoprecipitation data. Knock down studies using SLMAP siRNA with adipocytes resulted in a significant reduction in SLMAP and a decrease in glucose uptake. Thus, SLMAP may be an important regulator of glucose uptake or involved in GLUT-4 fusion/translocation into the plasma membrane of mouse abdominal adipose tissue and changes in SLMAP expression are linked to hyperglycemia and diabetes.
Collapse
|
49
|
Borgese N, Fasana E. Targeting pathways of C-tail-anchored proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:937-46. [DOI: 10.1016/j.bbamem.2010.07.010] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/09/2010] [Accepted: 07/10/2010] [Indexed: 10/19/2022]
|
50
|
Marchenko MM, Kopyl'chuk GP, Ketsa OV. [Effect of low doses of x-ray irradiation on the liver detoxication system in rats with transplanted Guerin's carcinoma]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2011; 56:266-73. [PMID: 21341514 DOI: 10.18097/pbmc20105602266] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The activity of detoxication enzymes in liver microsomal fraction of preliminary radiation-exposed rats was investigated. It was shown that preliminary organism exposure to radiation reduced cytochrome P450 and glutathione-S-transferase activity in liver microsomal fraction in the latent and logarithmic phases of oncogenesis compared with the unirradiated rats with tumor. Low level of cytochrome P450 activity can be caused by transition of microsomal cytochrome P450 in P420 inactive form. The preliminary radiation does not influence the enzyme activity of liver cytochrome P450 and glutathione-S-transferase on terminal stages of Guerin's carcinoma growth.
Collapse
|