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Lou G, Zhao Y, Zhao H, Zhang Y, Hao B, Qin L, Liu H, Liao S. Functional analysis of a novel nonsense variant c.91A>T of the TRAPPC2 gene in a Chinese family with X-linked recessive autosomal spondyloepiphyseal dysplasia tarda. Front Genet 2023; 14:1216592. [PMID: 37693308 PMCID: PMC10492639 DOI: 10.3389/fgene.2023.1216592] [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: 05/04/2023] [Accepted: 07/10/2023] [Indexed: 09/12/2023] Open
Abstract
Spondyloepiphyseal dysplasia tarda (SEDT) is a condition involving late-onset, X-linked recessive skeletal dysplasia caused by mutations in the TRAPPC2 gene. In this paper, we identified a novel nonsense variant in a SEDT pedigree and analyzed the function of the variant in an attempt to explain the new pathogenesis of the TRAPPC2 protein in SEDT. Briefly, DNA and RNA samples from the peripheral blood of SEDT individuals were prepared. The causative variant in the Chinese SEDT family was identified by clinic whole-exome sequencing analysis. Then, we observed the mRNA expression of TRAPPC2 in patients and the mutant TRAPPC2 level in vitro and analyzed the protein stability and subcellular distribution by cell fluorescence and Western blotting. We also investigated the effect of TRAPPC2 knockdown on the expression and secretion of COL2A1 in SW1353 cells or primary human chondrocytes. Herein, we found a nonsense variant, c.91A>T, of the TRAPPC2 gene in the pedigree. TRAPPC2 mRNA expression levels were significantly decreased in the available peripheral blood cell samples of two affected patients. An in vitro study showed that the mutant plasmid exhibited significantly lower mRNA and protein of TRAPPC2, and the mutant protein changed its membrane distribution. TRAPPC2 knockdown resulted in decreased COL2A1 expression and collagen II secretions. Our data indicate that the novel nonsense variant, c.91A>T, of the TRAPPC2 gene is the cause of SEDT in this pedigree. The variant results in a lowered expression of TRAPPC2 and then affects the COL2A1 expression and collagen II secretions, which may explain the mechanism of loss of function of the variant.
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Affiliation(s)
- Guiyu Lou
- Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Yuanyin Zhao
- Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Army Medical University, Chongqing, China
| | - Huiru Zhao
- Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Yuwei Zhang
- Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Bingtao Hao
- Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Litao Qin
- Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Hongyan Liu
- Henan Provincial People’s Hospital, Medical Genetics Institute of Henan Province, Henan Provincial Key Laboratory of Genetic Diseases and Functional Genomics, People’s Hospital of Zhengzhou University, Zhengzhou, China
| | - Shixiu Liao
- *Correspondence: Hongyan Liu, ; Shixiu Liao,
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Tang BL. Defects in early secretory pathway transport machinery components and neurodevelopmental disorders. Rev Neurosci 2021; 32:851-869. [PMID: 33781010 DOI: 10.1515/revneuro-2021-0020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 03/12/2021] [Indexed: 12/23/2022]
Abstract
The early secretory pathway, provisionally comprising of vesicular traffic between the endoplasmic reticulum (ER) and the Golgi apparatus, occurs constitutively in mammalian cells. Critical for a constant supply of secretory and plasma membrane (PM) materials, the pathway is presumably essential for general cellular function and survival. Neurons exhibit a high intensity in membrane dynamics and protein/lipid trafficking, with differential and polarized trafficking towards the somatodendritic and axonal PM domains. Mutations in genes encoding early secretory pathway membrane trafficking machinery components are known to result in neurodevelopmental or neurological disorders with disease manifestation in early life. Here, such rare disorders associated with autosomal recessive mutations in coat proteins, membrane tethering complexes and membrane fusion machineries responsible for trafficking in the early secretory pathway are summarily discussed. These mutations affected genes encoding subunits of coat protein complex I and II, subunits of transport protein particle (TRAPP) complexes, members of the YIP1 domain family (YIPF) and a SNAP receptor (SNARE) family member. Why the ubiquitously present and constitutively acting early secretory pathway machinery components could specifically affect neurodevelopment is addressed, with the plausible underlying disease etiologies and neuropathological mechanisms resulting from these mutations explored.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore117597, Singapore
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Zhang L, Wang J, Dong G, Wu D, Wu W. A novel missense variant in TRAPPC2 causes X-linked spondyloepiphyseal dysplasia tarda: A case report. Medicine (Baltimore) 2021; 100:e25169. [PMID: 33726005 PMCID: PMC7982231 DOI: 10.1097/md.0000000000025169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/25/2021] [Indexed: 01/05/2023] Open
Abstract
RATIONALE X-linked spondyloepiphyseal dysplasia tarda (X-linked SEDT) is a rare hereditary cause in childhood short stature due to mutations in trafficking protein particle complex subunit 2 (TRAPPC2) gene located on chromosome Xp22. Several pathogenic variants in TRAPPC2 have been reported, but missense variants are rare. PATIENT CONCERNS A 13-year, 8-month-old Chinese Han boy presenting with short stature for the past 7 years. DIAGNOSIS X-linked SEDT was established by a combination of clinical and radiographic features, confirmed by targeted next-generation sequencing. Genetic testing of the TRAPPC2 gene revealed a novel missense variant with c.260A>C (p.H87P) hemizygote in exon5. The mother was found to be a heterozygous TRAPPC2 carrier, whereas the father was normal. INTERVENTIONS Patient was treated with recombinant human growth hormone daily. Patient's height, glucose level, and possible progressive joint and back pain with osteoarthritis were under intensive observation regularly. OUTCOMES The patient achieved 2.1 cm height gain over the first 3 months' recombinant human growth hormone treatment without joint or back pain. However, the therapy was terminated because of increased glucose level on follow-up. LESSONS The short stature is a noteworthy problem for X-linked SEDT cases. We report a novel missense variant site in TRAPPC2 treated with growth hormone in the literature. We do not recommend the use of recombinant human growth hormone on patients with X-linked SEDT for the concern of glucose homeostasis.
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Affiliation(s)
| | | | | | - Dingwen Wu
- Department of Genetics and Metabolism, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Wei Wu
- Department of Endocrinology
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Zhang C, Du C, Ye J, Ye F, Wang R, Luo X, Liang Y. A novel deletion variant in TRAPPC2 causes spondyloepiphyseal dysplasia tarda in a five-generation Chinese family. BMC MEDICAL GENETICS 2020; 21:117. [PMID: 32471379 PMCID: PMC7260818 DOI: 10.1186/s12881-020-01052-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 05/19/2020] [Indexed: 11/25/2022]
Abstract
Background Spondyloepiphyseal dysplasia tarda (SEDT) is a rare X-linked recessive inherited osteochondrodysplasia caused by mutations in the TRAPPC2 gene. It is clinically characterized by disproportionate short stature and early onset of degenerative osteoarthritis. Clinical diagnosis can be challenging due to the late-onset of the disease and lack of systemic metabolic abnomalites. Genetic diagnosis is critical in both early diagnosis and management of the disease. Here we reported a five-generation Chinese SEDT family and described the novel molecular findings. Methods Detailed family history and clinical data were collected. Genomic DNA was extracted from venous blood samples of family members. The exons of genes known to be associated with skeletal disorders were captured and deep sequenced. Variants were annotated by ANNOVAR and associated with multiple databases. Putative variants were confirmed by Sanger sequencing. The identified variant was classified according to the American College of Medical Genetics (ACMG) criteria. Results The proband was a 27-year-old Chinese male who presented with short-trunk short stature and joint pain. His radiographs showed platyspondyly with posterior humping, narrow hip-joint surfaces, and pelvic osteosclerosis. A pedigree analysis of 5 generations with 6 affected males revealed an X-linked recessive mode of inheritance. Affected males were diagnosed as SEDT according to the clinical and radiological features. Next-generation sequencing identified a novel variant of c.216_217del in the exon 4 of TRAPPC2 gene in the proband and other affected males. This variant resulted in the shift of reading frame and early termination of protein translation (p.S73Gfs*15). The mother and maternal female relatives of the proband were heterozygous carriers of the same variant, while no variations were detected in this gene of his father and other unaffected males. Based on the ACMG criteria, the novel c.216_217del variant of the TRAPPC2 gene was the pathogenic variant of this SEDT family. Conclusion In this study we identified the novel pathogenic variant of of c.216_217del in the gene of TRAPPC2 in this five-generation Chinese SEDT family. Our findings expand the clinical and molecular spectrum of SEDT and helps the genetic diagnosis of SEDT patients.
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Affiliation(s)
- Cai Zhang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Caiqi Du
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Juan Ye
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Feng Ye
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Renfa Wang
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoping Luo
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yan Liang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Zappa F, Wilson C, Di Tullio G, Santoro M, Pucci P, Monti M, D'Amico D, Pisonero-Vaquero S, De Cegli R, Romano A, Saleem MA, Polishchuk E, Failli M, Giaquinto L, De Matteis MA. The TRAPP complex mediates secretion arrest induced by stress granule assembly. EMBO J 2019; 38:e101704. [PMID: 31429971 DOI: 10.15252/embj.2019101704] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/29/2022] Open
Abstract
The TRAnsport Protein Particle (TRAPP) complex controls multiple membrane trafficking steps and is strategically positioned to mediate cell adaptation to diverse environmental conditions, including acute stress. We have identified the TRAPP complex as a component of a branch of the integrated stress response that impinges on the early secretory pathway. The TRAPP complex associates with and drives the recruitment of the COPII coat to stress granules (SGs) leading to vesiculation of the Golgi complex and arrest of ER export. The relocation of the TRAPP complex and COPII to SGs only occurs in cycling cells and is CDK1/2-dependent, being driven by the interaction of TRAPP with hnRNPK, a CDK substrate that associates with SGs when phosphorylated. In addition, CDK1/2 inhibition impairs TRAPP complex/COPII relocation to SGs while stabilizing them at ER exit sites. Importantly, the TRAPP complex controls the maturation of SGs. SGs that assemble in TRAPP-depleted cells are smaller and are no longer able to recruit RACK1 and Raptor, two TRAPP-interactive signaling proteins, sensitizing cells to stress-induced apoptosis.
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Affiliation(s)
- Francesca Zappa
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | - Cathal Wilson
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | | | - Michele Santoro
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | | | | | - Davide D'Amico
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | | | - Rossella De Cegli
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | - Alessia Romano
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | - Moin A Saleem
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Elena Polishchuk
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | - Mario Failli
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | - Laura Giaquinto
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy
| | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Pozzuoli (Naples), Italy.,Federico II University, Naples, Italy
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6
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Sacher M, Shahrzad N, Kamel H, Milev MP. TRAPPopathies: An emerging set of disorders linked to variations in the genes encoding transport protein particle (TRAPP)-associated proteins. Traffic 2018; 20:5-26. [PMID: 30152084 DOI: 10.1111/tra.12615] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 08/23/2018] [Accepted: 08/26/2018] [Indexed: 02/06/2023]
Abstract
The movement of proteins between cellular compartments requires the orchestrated actions of many factors including Rab family GTPases, Soluble NSF Attachment protein REceptors (SNAREs) and so-called tethering factors. One such tethering factor is called TRAnsport Protein Particle (TRAPP), and in humans, TRAPP proteins are distributed into two related complexes called TRAPP II and III. Although thought to act as a single unit within the complex, in the past few years it has become evident that some TRAPP proteins function independently of the complex. Consistent with this, variations in the genes encoding these proteins result in a spectrum of human diseases with diverse, but partially overlapping, phenotypes. This contrasts with other tethering factors such as COG, where variations in the genes that encode its subunits all result in an identical phenotype. In this review, we present an up-to-date summary of all the known disease-related variations of genes encoding TRAPP-associated proteins and the disorders linked to these variations which we now call TRAPPopathies.
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Affiliation(s)
- Michael Sacher
- Department of Biology, Concordia University, Montreal, Quebec, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Nassim Shahrzad
- Department of Medicine, University of California, San Francisco, California
| | - Hiba Kamel
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Miroslav P Milev
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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Abstract
Introduction: Genetic skeletal diseases (GSDs) are a diverse and complex group of rare genetic conditions that affect the development and homeostasis of the skeleton. Although individually rare, as a group of related diseases, GSDs have an overall prevalence of at least 1 per 4,000 children. There are currently very few specific therapeutic interventions to prevent, halt or modify skeletal disease progression and therefore the generation of new and effective treatments requires novel and innovative research that can identify tractable therapeutic targets and biomarkers of these diseases. Areas covered: Remarkable progress has been made in identifying the genetic basis of the majority of GSDs and in developing relevant model systems that have delivered new knowledge on disease mechanisms and are now starting to identify novel therapeutic targets. This review will provide an overview of disease mechanisms that are shared amongst groups of different GSDs and describe potential therapeutic approaches that are under investigation. Expert opinion: The extensive clinical variability and genetic heterogeneity of GSDs renders this broad group of rare diseases a bench to bedside challenge. However, the evolving hypothesis that clinically different diseases might share common disease mechanisms is a powerful concept that will generate critical mass for the identification and validation of novel therapeutic targets and biomarkers.
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Affiliation(s)
- Michael D Briggs
- Newcastle University, Institute of Genetic Medicine, International Centre for Life , Central Parkway, Newcastle-upon-Tyne, NE1 3BZ, UK
| | - Peter A Bell
- Newcastle University, Institute of Genetic Medicine, International Centre for Life , Newcastle-upon-Tyne, NE1 3BZ, UK
| | - Michael J Wright
- Newcastle University, Institute of Genetic Medicine, International Centre for Life , Newcastle-upon-Tyne, NE1 3BZ, UK
| | - Katarzyna A Pirog
- Newcastle University, Institute of Genetic Medicine, International Centre for Life , Newcastle-upon-Tyne, NE1 3BZ, UK
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8
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Brunet S, Sacher M. In Sickness and in Health: The Role of TRAPP and Associated Proteins in Disease. Traffic 2014; 15:803-18. [PMID: 24917561 DOI: 10.1111/tra.12183] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/06/2014] [Accepted: 06/06/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Stephanie Brunet
- Department of Biology; Concordia University; 7141 Sherbrooke Street West, SP-457.01 Montreal QC H4B 1R6 Canada
| | - Michael Sacher
- Department of Biology; Concordia University; 7141 Sherbrooke Street West, SP-457.01 Montreal QC H4B 1R6 Canada
- Department of Anatomy and Cell Biology; McGill University; 845 Sherbrooke Street West Montreal QC H3A 0G4 Canada
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Horn T, Ivanov I, Di Venere A, Kakularam KR, Reddanna P, Conrad ML, Richter C, Scheerer P, Kuhn H. Molecular basis for the catalytic inactivity of a naturally occurring near-null variant of human ALOX15. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1702-13. [PMID: 23958500 DOI: 10.1016/j.bbalip.2013.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 08/02/2013] [Accepted: 08/06/2013] [Indexed: 11/15/2022]
Abstract
Mammalian lipoxygenases belong to a family of lipid-peroxidizing enzymes, which have been implicated in cardiovascular, hyperproliferative and neurodegenerative diseases. Here we report that a naturally occurring mutation in the hALOX15 gene leads to expression of a catalytically near-null enzyme variant (hGly422Glu). The inactivity may be related to severe misfolding of the enzyme protein, which was concluded from CD-spectra as well as from thermal and chemical stability assays. In silico mutagenesis experiments suggest that most mutations at hGly422 have the potential to induce sterical clash, which might be considered a reason for protein misfolding. hGly422 is conserved among ALOX5, ALOX12 and ALOX15 isoforms and corresponding hALOX12 and hALOX5 mutants also exhibited a reduced catalytic activity. Interestingly, in the hALOX5 Gly429Glu mutants the reaction specificity of arachidonic acid oxygenation was shifted from 5S- to 8S- and 12R-H(p)ETE formation. Taken together, our data indicate that the conserved glycine is of functional importance for these enzyme variants and most mutants at this position lose catalytic activity.
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Key Words
- (5Z,8Z,10E,14Z)-12-hydroperoxyeicosa-5,8,10,14-tetraenoic acid
- (5Z,8Z,11Z,13E)-15-hydroperoxyeicosa-5,8,11,13-tetraenoic acid
- (5Z,9E,11Z,14Z)-8-hydroperoxyicosa-5,9,11,14-tetraenoic acid
- (9Z,11E,13S)-13-hydroperoxyoctadeca-9,11-dienoic acid
- 12-H(p)ETE
- 13-H(p)ODE
- 15-H(p)ETE
- 8-H(p)ETE
- ALOX
- ALOX15
- ALOX15 gene variation
- HETE
- HpETE
- IPTG
- Isopropyl-β-d-thiogalactopyranoside
- LOXs
- Lipid peroxidation
- Lipoxygenase
- Misfolding
- UTR
- arachidonate lipoxygenase
- hydroperoxyeicosatetraenoic acid
- hydroxyeicosatetraenoic acid
- lipoxygenases
- untranslated region
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Affiliation(s)
- Thomas Horn
- Institute of Biochemistry, University Medicine Berlin-Charité, Charitéplatz 1, D-10117 Berlin, Germany.
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Taussig D, Lipatova Z, Kim JJ, Zhang X, Segev N. Trs20 is required for TRAPP II assembly. Traffic 2013; 14:678-90. [PMID: 23465091 DOI: 10.1111/tra.12065] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 02/22/2013] [Accepted: 03/07/2013] [Indexed: 11/28/2022]
Abstract
The modular TRAPP complexes act as nucleotide exchangers to activate the Golgi Ypt/Rab GTPases, Ypt1 and Ypt31/Ypt32. In yeast, TRAPP I acts at the cis-Golgi and its assembly and structure are well characterized. In contrast, TRAPP II acts at the trans-Golgi and is poorly understood. Especially puzzling is the role of Trs20, an essential TRAPP I/II subunit required neither for the assembly of TRAPP I nor for its Ypt1-exchange activity. Mutations in Sedlin, the human functional ortholog of Trs20, cause the cartilage-specific disorder SEDT. Here we show that Trs20 interacts with the TRAPP II-specific subunit Trs120. Furthermore, the Trs20-Trs120 interaction is required for assembly of TRAPP II and for its Ypt32-exchange activity. Finally, Trs20-D46Y, with a single-residue substitution equivalent to a SEDT-causing mutation in Sedlin, interacts with TRAPP I, but the resulting TRAPP complex cannot interact with Trs120 and TRAPP II cannot be assembled. These results indicate that Trs20 is crucial for assembly of TRAPP II, and the defective assembly caused by a SEDT-linked mutation suggests that this role is conserved.
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Affiliation(s)
- David Taussig
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
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11
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Yu S, Liang Y. A trapper keeper for TRAPP, its structures and functions. Cell Mol Life Sci 2012; 69:3933-44. [PMID: 22669257 PMCID: PMC11114727 DOI: 10.1007/s00018-012-1024-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/20/2012] [Accepted: 05/02/2012] [Indexed: 12/22/2022]
Abstract
During biosynthesis many membrane and secreted proteins are transported from the endoplasmic reticulum, through the Golgi and on to the plasma membrane in small transport vesicles. These transport vesicles have to undergo budding, movement, tethering, docking, and fusion at each organelle of the biosynthetic pathway. The transport protein particle (TRAPP) complex was initially identified as the tethering factor for endoplasmic reticulum (ER)-derived COPII vesicles, but the functions of TRAPP may extend to other areas of biology. Three forms of TRAPP complexes have been discovered to date, and recent advances in research have provided new insights on the structures and functions of TRAPP. Here we provide a comprehensive review of the recent findings in TRAPP biology.
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Affiliation(s)
- Sidney Yu
- School of Biomedical Sciences and Epithelial Cell Biology Research Center, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, People's Republic of China,
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12
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Zong M, Wu XG, Chan CWL, Choi MY, Chan HC, Tanner JA, Yu S. The adaptor function of TRAPPC2 in mammalian TRAPPs explains TRAPPC2-associated SEDT and TRAPPC9-associated congenital intellectual disability. PLoS One 2011; 6:e23350. [PMID: 21858081 PMCID: PMC3156116 DOI: 10.1371/journal.pone.0023350] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 07/13/2011] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The TRAPP (Transport protein particle) complex is a conserved protein complex functioning at various steps in vesicle transport. Although yeast has three functionally and structurally distinct forms, TRAPPI, II and III, emerging evidence suggests that mammalian TRAPP complex may be different. Mutations in the TRAPP complex subunit 2 (TRAPPC2) cause X-linked spondyloepiphyseal dysplasia tarda, while mutations in the TRAPP complex subunit 9 (TRAPPC9) cause postnatal mental retardation with microcephaly. The structural interplay between these subunits found in mammalian equivalent of TRAPPI and those specific to TRAPPII and TRAPPIII remains largely unknown and we undertook the present study to examine the interaction between these subunits. Here, we reveal that the mammalian equivalent of the TRAPPII complex is structurally distinct from the yeast counterpart thus leading to insight into mechanism of disease. PRINCIPAL FINDINGS We analyzed how TRAPPII- or TRAPPIII- specific subunits interact with the six-subunit core complex of TRAPP by co-immunoprecipitation in mammalian cells. TRAPPC2 binds to TRAPPII-specific subunit TRAPPC9, which in turn binds to TRAPPC10. Unexpectedly, TRAPPC2 can also bind to the putative TRAPPIII-specific subunit, TRAPPC8. Endogenous TRAPPC9-positive TRAPPII complex does not contain TRAPPC8, suggesting that TRAPPC2 binds to either TRAPPC9 or TRAPPC8 during the formation of the mammalian equivalents of TRAPPII or TRAPPIII, respectively. Therefore, TRAPPC2 serves as an adaptor for the formation of these complexes. A disease-causing mutation of TRAPPC2, D47Y, failed to interact with either TRAPPC9 or TRAPPC8, suggesting that aspartate 47 in TRAPPC2 is at or near the site of interaction with TRAPPC9 or TRAPPC8, mediating the formation of TRAPPII and/or TRAPPIII. Furthermore, disease-causing deletional mutants of TRAPPC9 all failed to interact with TRAPPC2 and TRAPPC10. CONCLUSIONS TRAPPC2 serves as an adaptor for the formation of TRAPPII or TRAPPIII in mammalian cells. The mammalian equivalent of TRAPPII is likely different from the yeast TRAPPII structurally.
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Affiliation(s)
- Min Zong
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
| | - Xing-gang Wu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
| | - Cecilia W. L. Chan
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, People's Republic of China
| | - Mei Y. Choi
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, People's Republic of China
| | - Hsiao Chang Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
- Epithelial Cell Biology Research Center, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
| | - Julian A. Tanner
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong SAR, People's Republic of China
| | - Sidney Yu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
- Epithelial Cell Biology Research Center, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People's Republic of China
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13
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Identification of a DNA aptamer that inhibits sclerostin's antagonistic effect on Wnt signalling. Biochem J 2011; 434:493-501. [PMID: 21204783 DOI: 10.1042/bj20101096] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sclerostin is an extracellular negative regulator of bone formation that is a recognized therapeutic target for osteoporosis therapy. In the present study, we performed DNA aptamer selection against sclerostin, then characterized aptamer-sclerostin binding and the ability to inhibit sclerostin function in cell culture. We show that a selected DNA aptamer was highly selective for binding to sclerostin with affinities in the nanomolar range as determined by solid-phase assays and by isothermal titration calorimetry. Binding between sclerostin and the aptamer was exothermic and enthalpically driven. CD confirmed that the aptamer had temperature-dependent parallel G-quadruplex characteristics. The aptamer was stabilized with 3' inverted thymidine to investigate efficacy at inhibiting sclerostin function in cell culture. The stabilized DNA aptamer showed potent and specific dose-dependent inhibition of sclerostin's antagonistic effect on Wnt activity using a reporter assay. Taken together, the present findings suggest an alternative approach to inhibiting sclerostin function with therapeutic potential.
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Shum KT, Lui ELH, Wong SCK, Yeung P, Sam L, Wang Y, Watt RM, Tanner JA. Aptamer-mediated inhibition of Mycobacterium tuberculosis polyphosphate kinase 2. Biochemistry 2011; 50:3261-71. [PMID: 21381755 DOI: 10.1021/bi2001455] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Inorganic polyphosphate (polyP) plays a number of critical roles in bacterial persistence, stress, and virulence. PolyP intracellular metabolism is regulated by the polyphosphate kinase (PPK) protein families, and inhibition of PPK activity is a potential approach to disrupting polyP-dependent processes in pathogenic organisms. Here, we biochemically characterized Mycobacterium tuberculosis (MTB) PPK2 and developed DNA-based aptamers that inhibit the enzyme's catalytic activities. MTB PPK2 catalyzed polyP-dependent phosphorylation of ADP to ATP at a rate 838 times higher than the rate of polyP synthesis. Gel filtration chromatography suggested MTB PPK2 to be an octamer. DNA aptamers were isolated against MTB PPK2. Circular dichroism revealed that aptamers grouped into two distinct classes of secondary structure; G-quadruplex and non-G-quadruplex. A selected G-quadruplex aptamer was highly selective for binding to MTB PPK2 with a dissociation constant of 870 nM as determined by isothermal titration calorimetry. The binding between MTB PPK2 and the aptamer was exothermic yet primarily driven by entropy. This G-quadruplex aptamer inhibited MTB PPK2 with an IC(50) of 40 nM and exhibited noncompetitive inhibition kinetics. Mutational mechanistic analysis revealed an aptamer G-quadruplex motif is critical for enzyme inhibition. The aptamer was also tested against Vibrio cholerae PPK2, where it showed an IC(50) of 105 nM and insignificant inhibition against more distantly related Laribacter hongkongensis PPK2.
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Affiliation(s)
- Ka To Shum
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
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Yip CK, Berscheminski J, Walz T. Molecular architecture of the TRAPPII complex and implications for vesicle tethering. Nat Struct Mol Biol 2010; 17:1298-304. [PMID: 20972447 PMCID: PMC2988884 DOI: 10.1038/nsmb.1914] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 08/19/2010] [Indexed: 01/04/2023]
Abstract
Multi-subunit tethering complexes participate in the process of vesicle tethering, the initial interaction between transport vesicles and their acceptor compartments. TRAPPII is a highly conserved tethering complex that functions in the late Golgi and consists of all TRAPPI and three specific subunits. We have purified native yeast TRAPPII and characterized its structure and subunit organization by single-particle electron microscopy. Our data show that the nine TRAPPII components form a core complex that dimerizes into a three-layered, diamond-shaped structure. The TRAPPI subunits assemble into TRAPPI complexes that form the outer layers. The three TRAPPII-specific subunits cap the ends of TRAPPI and form the middle layer responsible for dimerization. TRAPPII binds Ypt1 and likely uses the TRAPPI catalytic core to promote guanine nucleotide exchange. We discuss implications of the TRAPPII structure for coat interaction and TRAPPII-associated human pathologies.
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Affiliation(s)
- Calvin K Yip
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
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