1
|
Kim WD, DiGiacinto AF, Huber RJ. Assaying Lysosomal Enzyme Activity in Dictyostelium discoideum. Methods Mol Biol 2024; 2814:55-79. [PMID: 38954197 DOI: 10.1007/978-1-0716-3894-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Lysosomes are membrane-enclosed organelles that digest intracellular material. They contain more than 50 different enzymes that can degrade a variety of macromolecules including nucleic acids, proteins, polysaccharides, and lipids. In addition to functioning within lysosomes, lysosomal enzymes are also secreted. Alterations in the levels and activities of lysosomal enzymes dysregulates lysosomes, which can lead to the intralysosomal accumulation of biological material and the development of lysosomal storage diseases (LSDs) in humans. Dictyostelium discoideum has a long history of being used to study the trafficking and functions of lysosomal enzymes. More recently, it has been used as a model system to study several LSDs. In this chapter, we outline the methods for assessing the activity of several lysosomal enzymes in D. discoideum (α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, β-N-acetylglucosaminidase, α-mannosidase, cathepsin B, cathepsin D, cathepsin F, palmitoyl protein thioesterase 1, and tripeptidyl peptidase 1).
Collapse
Affiliation(s)
- William D Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | | | - Robert J Huber
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada.
- Department of Biology, Trent University, Peterborough, ON, Canada.
| |
Collapse
|
2
|
Kim WD, Huber RJ. An altered transcriptome underlies cln5-deficiency phenotypes in Dictyostelium discoideum. Front Genet 2022; 13:1045738. [DOI: 10.3389/fgene.2022.1045738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 10/27/2022] [Indexed: 11/11/2022] Open
Abstract
Mutations in CLN5 cause a subtype of neuronal ceroid lipofuscinosis (NCL) called CLN5 disease. The NCLs, commonly referred to as Batten disease, are a family of neurodegenerative lysosomal storage diseases that affect all ages and ethnicities globally. Previous research showed that CLN5 participates in a variety of cellular processes. However, the precise function of CLN5 in the cell and the pathway(s) regulating its function are not well understood. In the model organism Dictyostelium discoideum, loss of the CLN5 homolog, cln5, impacts various cellular and developmental processes including cell proliferation, cytokinesis, aggregation, cell adhesion, and terminal differentiation. In this study, we used comparative transcriptomics to identify differentially expressed genes underlying cln5-deficiency phenotypes during growth and the early stages of multicellular development. During growth, genes associated with protein ubiquitination/deubiquitination, cell cycle progression, and proteasomal degradation were affected, while genes linked to protein and carbohydrate catabolism were affected during early development. We followed up this analysis by showing that loss of cln5 alters the intracellular and extracellular amounts of proliferation repressors during growth and increases the extracellular amount of conditioned medium factor, which regulates cAMP signalling during the early stages of development. Additionally, cln5- cells displayed increased intracellular and extracellular amounts of discoidin, which is involved in cell-substrate adhesion and migration. Previous work in mammalian models reported altered lysosomal enzyme activity due to mutation or loss of CLN5. Here, we detected altered intracellular activities of various carbohydrate enzymes and cathepsins during cln5- growth and starvation. Notably, cln5- cells displayed reduced β-hexosaminidase activity, which aligns with previous work showing that D. discoideum Cln5 and human CLN5 can cleave the substrate acted upon by β-hexosaminidase. Finally, consistent with the differential expression of genes associated with proteasomal degradation in cln5- cells, we also observed elevated amounts of a proteasome subunit and reduced proteasome 20S activity during cln5- growth and starvation. Overall, this study reveals the impact of cln5-deficiency on gene expression in D. discoideum, provides insight on the genes and proteins that play a role in regulating Cln5-dependent processes, and sheds light on the molecular mechanisms underlying CLN5 disease.
Collapse
|
3
|
Wang W, Wang Y, Dong G, Chen F. Development of Cordyceps javanica BE01 with enhanced virulence against Hyphantria cunea using polyethylene glycol-mediated protoplast transformation. Front Microbiol 2022; 13:972425. [PMID: 36118242 PMCID: PMC9478556 DOI: 10.3389/fmicb.2022.972425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 08/15/2022] [Indexed: 11/24/2022] Open
Abstract
Cordyceps javanica has promising application prospects as an entomopathogenic fungus with a wide range of hosts. To enhance the virulence of C. javanica, a polyethylene glycol (PEG)-mediated protoplast genetic transformation system was constructed. Strains overexpressing the subtilisin-like protease genes CJPRB and CJPRB1 and the tripeptidyl peptidase gene CJCLN2-1 were constructed with this system, and the effects of these strains on Hyphantria cunea were tested. The aminoglycoside G418 was used at 800 μg ml−1 to screen the transformants. C. javanica hyphae were degraded with an enzyme mixture to obtain protoplasts at 1.31 × 107 protoplasts ml−1. The transformation of 2 μg of DNA into 1,000 protoplasts was achieved with 20% PEG2000, and after 6 h of recovery, the transformation efficiency was 12.33 ± 1.42 transformants μg−1 plasmid. The LT50 values of CJPRB, CJPRB1, and CJCLN2-1-overexpressing C. javanica strains were 1.32-fold, 2.21-fold, and 2.14-fold higher than that of the wild-type (WT) strain, respectively. The three overexpression strains showed no significant differences from the WT strain in terms of colony growth, conidial yield, and conidial germination rate. However, the infection rate of the CJPRB1 strain was faster than that of the WT strain, with infection occurring within 4–5 days. The CJCLN2-1 strain had a significantly higher mortality rate than the WT strain within 4–10 days after infection. A C. javanica genetic transformation system was successfully constructed for the first time, and an overexpression strain exhibited enhanced virulence to H. cunea compared with the WT strain.
Collapse
Affiliation(s)
- Wenxiu Wang
- Collaborative Innovation Center of Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, China
| | - Yahong Wang
- Collaborative Innovation Center of Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, China
| | - Guangping Dong
- Key Laboratory of State Forestry Administration on Pine Wilt Disease Prevention and Control, Hefei, China
| | - Fengmao Chen
- Collaborative Innovation Center of Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, China
- *Correspondence: Fengmao Chen,
| |
Collapse
|
4
|
Yap SQ, Kim WD, Huber RJ. Mfsd8 Modulates Growth and the Early Stages of Multicellular Development in Dictyostelium discoideum. Front Cell Dev Biol 2022; 10:930235. [PMID: 35756993 PMCID: PMC9218796 DOI: 10.3389/fcell.2022.930235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 05/23/2022] [Indexed: 11/17/2022] Open
Abstract
MFSD8 is a transmembrane protein that has been reported to transport chloride ions across the lysosomal membrane. Mutations in MFSD8 are associated with a subtype of Batten disease called CLN7 disease. Batten disease encompasses a family of 13 inherited neurodegenerative lysosomal storage diseases collectively referred to as the neuronal ceroid lipofuscinoses (NCLs). Previous work identified an ortholog of human MFSD8 in the social amoeba D. discoideum (gene: mfsd8, protein: Mfsd8), reported its localization to endocytic compartments, and demonstrated its involvement in protein secretion. In this study, we further characterized the effects of mfsd8 loss during D. discoideum growth and early stages of multicellular development. During growth, mfsd8− cells displayed increased rates of proliferation, pinocytosis, and expansion on bacterial lawns. Loss of mfsd8 also increased cell size, inhibited cytokinesis, affected the intracellular and extracellular levels of the quorum-sensing protein autocrine proliferation repressor A, and altered lysosomal enzyme activity. During the early stages of development, loss of mfsd8 delayed aggregation, which we determined was at least partly due to impaired cell-substrate adhesion, defects in protein secretion, and alterations in lysosomal enzyme activity. Overall, these results show that Mfsd8 plays an important role in modulating a variety of processes during the growth and early development of D. discoideum.
Collapse
Affiliation(s)
- Shyong Quan Yap
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - William D Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Robert J Huber
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada.,Department of Biology, Trent University, Peterborough, ON, Canada
| |
Collapse
|
5
|
Kim WD, Wilson-Smillie MLDM, Thanabalasingam A, Lefrancois S, Cotman SL, Huber RJ. Autophagy in the Neuronal Ceroid Lipofuscinoses (Batten Disease). Front Cell Dev Biol 2022; 10:812728. [PMID: 35252181 PMCID: PMC8888908 DOI: 10.3389/fcell.2022.812728] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/24/2022] [Indexed: 12/22/2022] Open
Abstract
The neuronal ceroid lipofuscinoses (NCLs), also referred to as Batten disease, are a family of neurodegenerative diseases that affect all age groups and ethnicities around the globe. At least a dozen NCL subtypes have been identified that are each linked to a mutation in a distinct ceroid lipofuscinosis neuronal (CLN) gene. Mutations in CLN genes cause the accumulation of autofluorescent lipoprotein aggregates, called ceroid lipofuscin, in neurons and other cell types outside the central nervous system. The mechanisms regulating the accumulation of this material are not entirely known. The CLN genes encode cytosolic, lysosomal, and integral membrane proteins that are associated with a variety of cellular processes, and accumulated evidence suggests they participate in shared or convergent biological pathways. Research across a variety of non-mammalian and mammalian model systems clearly supports an effect of CLN gene mutations on autophagy, suggesting that autophagy plays an essential role in the development and progression of the NCLs. In this review, we summarize research linking the autophagy pathway to the NCLs to guide future work that further elucidates the contribution of altered autophagy to NCL pathology.
Collapse
Affiliation(s)
- William D. Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | | | - Aruban Thanabalasingam
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Stephane Lefrancois
- Centre Armand-Frappier Santé Biotechnologie, Institut National de La Recherche Scientifique, Laval, QC, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, Canada
- Centre D'Excellence en Recherche sur Les Maladies Orphelines–Fondation Courtois (CERMO-FC), Université Du Québec à Montréal (UQAM), Montréal, QC, Canada
| | - Susan L. Cotman
- Department of Neurology, Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Harvard Medical School, Boston, MA, United States
| | - Robert J. Huber
- Department of Biology, Trent University, Peterborough, ON, Canada
| |
Collapse
|
6
|
Storey CL, Williams RSB, Fisher PR, Annesley SJ. Dictyostelium discoideum: A Model System for Neurological Disorders. Cells 2022; 11:cells11030463. [PMID: 35159273 PMCID: PMC8833889 DOI: 10.3390/cells11030463] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/23/2022] [Accepted: 01/24/2022] [Indexed: 12/14/2022] Open
Abstract
Background: The incidence of neurological disorders is increasing due to population growth and extended life expectancy. Despite advances in the understanding of these disorders, curative strategies for treatment have not yet eventuated. In part, this is due to the complexities of the disorders and a lack of identification of their specific underlying pathologies. Dictyostelium discoideum has provided a useful, simple model to aid in unraveling the complex pathological characteristics of neurological disorders including Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, neuronal ceroid lipofuscinoses and lissencephaly. In addition, D. discoideum has proven to be an innovative model for pharmaceutical research in the neurological field. Scope of review: This review describes the contributions of D. discoideum in the field of neurological research. The continued exploration of proteins implicated in neurological disorders in D. discoideum may elucidate their pathological roles and fast-track curative therapeutics.
Collapse
Affiliation(s)
- Claire Louise Storey
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora 3086, Australia; (C.L.S.); (P.R.F.)
| | - Robin Simon Brooke Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK;
| | - Paul Robert Fisher
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora 3086, Australia; (C.L.S.); (P.R.F.)
| | - Sarah Jane Annesley
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora 3086, Australia; (C.L.S.); (P.R.F.)
- Correspondence: ; Tel.: +61-394-791-412
| |
Collapse
|
7
|
McLaren MD, Mathavarajah S, Kim WD, Yap SQ, Huber RJ. Aberrant Autophagy Impacts Growth and Multicellular Development in a Dictyostelium Knockout Model of CLN5 Disease. Front Cell Dev Biol 2021; 9:657406. [PMID: 34291044 PMCID: PMC8287835 DOI: 10.3389/fcell.2021.657406] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 05/28/2021] [Indexed: 12/22/2022] Open
Abstract
Mutations in CLN5 cause a subtype of neuronal ceroid lipofuscinosis (NCL) called CLN5 disease. While the precise role of CLN5 in NCL pathogenesis is not known, recent work revealed that the protein has glycoside hydrolase activity. Previous work on the Dictyostelium discoideum homolog of human CLN5, Cln5, revealed its secretion during the early stages of development and its role in regulating cell adhesion and cAMP-mediated chemotaxis. Here, we used Dictyostelium to examine the effect of cln5-deficiency on various growth and developmental processes during the life cycle. During growth, cln5– cells displayed reduced cell proliferation, cytokinesis, viability, and folic acid-mediated chemotaxis. In addition, the growth of cln5– cells was severely impaired in nutrient-limiting media. Based on these findings, we assessed autophagic flux in growth-phase cells and observed that loss of cln5 increased the number of autophagosomes suggesting that the basal level of autophagy was increased in cln5– cells. Similarly, loss of cln5 increased the amounts of ubiquitin-positive proteins. During the early stages of multicellular development, the aggregation of cln5– cells was delayed and loss of the autophagy genes, atg1 and atg9, reduced the extracellular amount of Cln5. We also observed an increased amount of intracellular Cln5 in cells lacking the Dictyostelium homolog of the human glycoside hydrolase, hexosaminidase A (HEXA), further supporting the glycoside hydrolase activity of Cln5. This observation was also supported by our finding that CLN5 and HEXA expression are highly correlated in human tissues. Following mound formation, cln5– development was precocious and loss of cln5 affected spore morphology, germination, and viability. When cln5– cells were developed in the presence of the autophagy inhibitor ammonium chloride, the formation of multicellular structures was impaired, and the size of cln5– slugs was reduced relative to WT slugs. These results, coupled with the aberrant autophagic flux observed in cln5– cells during growth, support a role for Cln5 in autophagy during the Dictyostelium life cycle. In total, this study highlights the multifaceted role of Cln5 in Dictyostelium and provides insight into the pathological mechanisms that may underlie CLN5 disease.
Collapse
Affiliation(s)
- Meagan D McLaren
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | | | - William D Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Shyong Q Yap
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Robert J Huber
- Department of Biology, Trent University, Peterborough, ON, Canada
| |
Collapse
|
8
|
Christopher M, Kooloth-Valappil P, Sreeja-Raju A, Sukumaran RK. Repurposing proteases: An in-silico analysis of the binding potential of extracellular fungal proteases with selected viral proteins. ACTA ACUST UNITED AC 2021; 15:100756. [PMID: 34226889 PMCID: PMC8245309 DOI: 10.1016/j.biteb.2021.100756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 12/29/2022]
Abstract
Proteases have long been the target of many drugs, but their potential as therapeutic agents is a well-known, but under-explored area. Due to the heightened threat from new and emerging infectious agents, it is worthwhile to tap into the vast microbial protease resource to identify potential therapeutics. By docking proteases of the fungus Penicillium janthinellum NCIM 1366 with the proteins encoded by the SARS-CoV-2 virus, the enzymes that have the potential to bind with, and thereby degrade viral proteins were identified. In-silico docking analysis revealed that both fungal and commercially available proteases belonging to the A1A, M20A, S10, S8A and T1A families were able to bind the viral spike, envelope, ORF-7a and Nsp2 proteins (binding energy < -50 kJ/mol), thereby opening up the possibility of developing additional therapeutic applications for these enzymes.
Collapse
Affiliation(s)
- Meera Christopher
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Pappanamcode, Thiruvananthapuram 695019, Kerala, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Prajeesh Kooloth-Valappil
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Pappanamcode, Thiruvananthapuram 695019, Kerala, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Athiraraj Sreeja-Raju
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Pappanamcode, Thiruvananthapuram 695019, Kerala, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Rajeev K Sukumaran
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR- National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Pappanamcode, Thiruvananthapuram 695019, Kerala, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| |
Collapse
|
9
|
Jin YN, Cui ZH, Ma K, Yao JL, Ruan YY, Guo ZF. Characterization of ZmCOLD1, novel GPCR-Type G Protein genes involved in cold stress from Zea mays L. and the evolution analysis with those from other species. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2021; 27:619-632. [PMID: 33854288 PMCID: PMC7981359 DOI: 10.1007/s12298-021-00966-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 02/27/2021] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
Maize is one of the most vital staple crops worldwide. G proteins modulate plentiful signaling pathways, and G protein-coupled receptor-type G proteins (GPCRs) are highly conserved membrane proteins in plants. However, researches on maize G proteins and GPCRs are scarce. In this study, we identified three novel GPCR-Type G Protein (GTG) genes from chromosome 10 (Chr 10) in maize, designated as ZmCOLD1-10A, ZmCOLD1-10B and ZmCOLD1-10C. Their amino acid sequences had high similarity to TaCOLD1 from wheat and OsCOLD1 from rice. They contained the basic characteristics of GTG/COLD1 proteins, including GPCR-like topology, the conserved hydrophilic loop (HL) domain, DUF3735 (domain of unknown function 3735) domain, GTPase-activating domain, and ATP/GTP-binding domain. Subcellular localization analyses of ZmCOLD1 proteins suggested that ZmCOLD1 proteins localized on plasma membrane (PM) and endoplasmic reticulum (ER). Furthermore, amino acid sequence alignment verified the conservation of the key 187th amino acid T in maize and other wild maize-relative species. Evolutionary relationship among plants GTG/COLD1 proteins family displayed strong group-specificity. Expression analysis indicated that ZmCOLD1-10A was cold-induced and inhibited by light. Together, these results suggested that ZmCOLD1 genes had potential value to improve cold tolerance and to contribute crops growth and molecular breeding.
Collapse
Affiliation(s)
- Ya-Nan Jin
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866 China
- College of Life Science, Inner Mongolia University for the Nationalities, Tongliao, 028000 China
| | - Zhen-hai Cui
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866 China
| | - Ke Ma
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866 China
| | - Jia-Lu Yao
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866 China
| | - Yan-Ye Ruan
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866 China
| | - Zhi-Fu Guo
- College of Bioscience and Biotechnology, Shenyang Agricultural University, Shenyang, 110866 China
| |
Collapse
|
10
|
Huber RJ, Mathavarajah S, Yap SQ. Mfsd8 localizes to endocytic compartments and influences the secretion of Cln5 and cathepsin D in Dictyostelium. Cell Signal 2020; 70:109572. [PMID: 32087303 DOI: 10.1016/j.cellsig.2020.109572] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/13/2022]
Abstract
The neuronal ceroid lipofuscinoses (NCLs) are a family of neurodegenerative diseases that affect people of all ages and ethnicities, yet many of the associated genes/proteins are not well characterized. Mutations in MFSD8 (major facilitator superfamily domain-containing 8) cause an infantile form of NCL referred to as CLN7 disease. In this study, we revealed the localization and binding partners of an ortholog of human MFSD8 (Mfsd8) in the social amoeba Dictyostelium discoideum. Putative lysosomal targeting motifs are conserved in Dictyostelium Mfsd8, as are several residues mutated in CLN7 disease patients. Mfsd8 tagged with GFP localizes to endocytic compartments, which includes acidic intracellular vesicles and late endosomes. We pulled-down GFP-Mfsd8 and used mass spectrometry to reveal the Mfsd8 interactome during Dictyostelium growth and starvation. Among the identified hits were the Dictyostelium ortholog of human cathepsin D (CtsD), as well as proteins linked to the functions of the CLN3 (Cln3) and CLN5 (Cln5) orthologs in Dictyostelium. To study the function of Mfsd8, we validated a publically available mfsd8- cell line (GWDI Project) and then used this knockout cell line to show that Mfsd8 influences the secretion of Cln5 and CtsD. This information is then integrated into an emerging model describing the molecular networking of NCL proteins in Dictyostelium. In total, this study identifies Dictyostelium as a new model system for studying CLN7 disease.
Collapse
Affiliation(s)
- Robert J Huber
- Department of Biology, Trent University, Peterborough, Ontario, Canada.
| | | | - Shyong Quan Yap
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| |
Collapse
|
11
|
Huber RJ. Molecular networking in the neuronal ceroid lipofuscinoses: insights from mammalian models and the social amoeba Dictyostelium discoideum. J Biomed Sci 2020; 27:64. [PMID: 32430003 PMCID: PMC7238602 DOI: 10.1186/s12929-020-00653-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 04/22/2020] [Indexed: 12/26/2022] Open
Abstract
The neuronal ceroid lipofuscinoses (NCLs), commonly known as Batten disease, belong to a family of neurological disorders that cause blindness, seizures, loss of motor function and cognitive ability, and premature death. There are 13 different subtypes of NCL that are associated with mutations in 13 genetically distinct genes (CLN1-CLN8, CLN10-CLN14). Similar clinical and pathological profiles of the different NCL subtypes suggest that common disease mechanisms may be involved. As a result, there have been many efforts to determine how NCL proteins are connected at the cellular level. A main driving force for NCL research has been the utilization of mammalian and non-mammalian cellular models to study the mechanisms underlying the disease. One non-mammalian model that has provided significant insight into NCL protein function is the social amoeba Dictyostelium discoideum. Accumulated data from Dictyostelium and mammalian cells show that NCL proteins display similar localizations, have common binding partners, and regulate the expression and activities of one another. In addition, genetic models of NCL display similar phenotypes. This review integrates findings from Dictyostelium and mammalian models of NCL to highlight our understanding of the molecular networking of NCL proteins. The goal here is to help set the stage for future work to reveal the cellular mechanisms underlying the NCLs.
Collapse
Affiliation(s)
- Robert J Huber
- Department of Biology, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9L 0G2, Canada.
| |
Collapse
|
12
|
Specchio N, Pietrafusa N, Trivisano M. Changing Times for CLN2 Disease: The Era of Enzyme Replacement Therapy. Ther Clin Risk Manag 2020; 16:213-222. [PMID: 32280231 PMCID: PMC7127909 DOI: 10.2147/tcrm.s241048] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/18/2020] [Indexed: 01/23/2023] Open
Abstract
Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is a progressive neurodegenerative disease that results in early-onset, severe, progressive, neurological disabilities, leading to death in late childhood or early adolescence. Management has relied on symptomatic care, and supportive and palliative strategies, but the approval of the enzyme replacement therapy cerliponase alfa in the USA and Europe in 2017 brought different treatment opportunities. We describe the natural history of CLN2 disease, its diagnosis and management, and the preclinical and clinical development of cerliponase alfa. A PubMed search was undertaken for cerliponase alfa and rhTPP1 to identify preclinical and clinical studies. The hallmark-presenting symptoms of CLN2 disease are unprovoked seizures and a history of language delay, and progression involves motor dysfunction, and cognitive and visual decline. Cerliponase alfa has shown efficacy and tolerability in mouse and canine models of CLN2 disease when delivered intracerebroventricularly. Administration of cerliponase alfa in patients with CLN2 disease has led to significant reductions in the rate of decline of motor and language functions in comparison with a natural history population. The approval of cerliponase alfa has brought a new era for CLN2 disease, highlighting the need to understand different patterns of disease progression and clinical needs in treated patients.
Collapse
Affiliation(s)
- Nicola Specchio
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Nicola Pietrafusa
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Marina Trivisano
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| |
Collapse
|
13
|
Cellular models of Batten disease. Biochim Biophys Acta Mol Basis Dis 2019; 1866:165559. [PMID: 31655107 PMCID: PMC7338907 DOI: 10.1016/j.bbadis.2019.165559] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 09/05/2019] [Accepted: 09/13/2019] [Indexed: 12/22/2022]
Abstract
The Neuronal Ceroid Lipofuscinoses (NCL), otherwise known as Batten disease, are a group of neurodegenerative diseases caused by mutations in 13 known genes. All except one NCL is autosomal recessive in inheritance, with similar aetiology and characterised by the accumulation of autofluorescent storage material in the lysosomes of cells. Age of onset and the rate of progression vary between the NCLs. They are collectively one of the most common lysosomal storage diseases, but the enigma remains of how genetically distinct diseases result in such remarkably similar pathogenesis. Much has been learnt from cellular studies about the function of the proteins encoded by the affected genes. Such research has utilised primitive unicellular models such as yeast and amoeba containing gene orthologues, cells derived from naturally occurring (sheep) and genetically engineered (mouse) animal models or patient-derived cells. Most recently, patient-derived induced pluripotent stem cell (iPSC) lines have been differentiated into neural cell-types to study molecular pathogenesis in the cells most profoundly affected by disease. Here, we review how cell models have informed much of the biochemical understanding of the NCLs and how more complex models are being used to further this understanding and potentially act as platforms for therapeutic efficacy studies in the future. Developments made in cellular models for neuronal ceroid lipofuscinosis (NCL) in basic biology and use as therapeutic platforms. Cellular models elucidating function of NCL proteins. NCL proteins implicated in the mTor signalling pathway. Patient-derived induced pluripotent stem cell (iPSC) lines have been differentiated into neural cell-types providing insights into the molecular pathogenesis of NCL.
Collapse
|
14
|
Gerisch G, Prassler J, Butterfield N, Ecke M. Actin Waves and Dynamic Patterning of the Plasma Membrane. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:397-411. [PMID: 31543704 PMCID: PMC6747932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Plasma membrane and underlying actin network are connected to a functional unit that by non-linear interactions is capable of forming patterns. For instance, in cell motility and chemotaxis, cells polarize to form a protruding front and a retracting tail. Here we address dynamic patterns that are formed on a planar substrate surface and are therefore easily accessible to optical recording. In these patterns two distinct areas of the membrane and actin cortex are interconverted at the site of circular actin waves. The inner territory circumscribed by a wave is distinguished from the external area by a high PIP3 content and high Ras activity. In contrast, the external area is occupied with the PIP3-degrading phosphatase PTEN. In the underlying cortex, these areas differ in the proteins associated with the actin network. Actin waves can be formed at zones of increasing as well as decreasing Ras activity. Both types of waves are headed by myosin IB. When waves collide, they usually extinguish each other, and their decay is accompanied by the accumulation of coronin. No membrane patterns have been observed after efficient depolymerization of actin, suggesting that residual actin filaments are necessary for the pattern generating system to work. Where appropriate, we relate the experimental data obtained with Dictyostelium to human normal and malignant cell behavior, in particular to the role of Ras-GAP as an enhancer of macropinocytosis, to mutations in the tumor suppressor PTEN, to frustrated phagocytosis, and to the role of coronin in immune cells and neurons.
Collapse
Affiliation(s)
- Guenther Gerisch
- To whom all correspondence should be addressed: Dr. Günther Gerisch, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; Tel: +49 89 8578-2326, Fax: +49 89 8578-3885,
| | | | | | | |
Collapse
|
15
|
Gardner E, Bailey M, Schulz A, Aristorena M, Miller N, Mole SE. Mutation update: Review of TPP1 gene variants associated with neuronal ceroid lipofuscinosis CLN2 disease. Hum Mutat 2019; 40:1924-1938. [PMID: 31283065 PMCID: PMC6851559 DOI: 10.1002/humu.23860] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 06/25/2019] [Accepted: 06/28/2019] [Indexed: 01/03/2023]
Abstract
Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is an autosomal recessive condition caused by variants in the TPP1 gene, leading to deficient activity of the lysosomal enzyme tripeptidyl peptidase I (TPP1). We update on the spectrum of TPP1 variants associated with CLN2 disease, comprising 131 unique variants from 389 individuals (717 alleles) collected from the literature review, public databases, and laboratory communications. Previously unrecorded individuals were added to the UCL TPP1‐specific database. Two known pathogenic variants, c.509–1 G>C and c.622 C>T (p.(Arg208*)), collectively occur in 60% of affected individuals in the sample, and account for 50% of disease‐associated alleles. At least 86 variants (66%) are private to single families. Homozygosity occurs in 45% of individuals where both alleles are known (87% of reported individuals). Atypical CLN2 disease, TPP1 enzyme deficiency with disease onset and/or progression distinct from classic late‐infantile CLN2, represents 13% of individuals recorded with associated phenotype. NCBI ClinVar currently holds records for 37% of variants collected here. Effective CLN2 disease management requires early diagnosis; however, irreversible neurodegeneration occurs before a diagnosis is typically reached at age 5. Timely classification and public reporting of TPP1 variants is essential as molecular testing increases in use as a first‐line diagnostic test for pediatric‐onset neurological disease.
Collapse
Affiliation(s)
- Emily Gardner
- UCL MRC Laboratory for Molecular Cell Biology and UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Mitch Bailey
- Global Scientific Affairs, BioMarin Pharmaceutical Inc, Novato, California
| | - Angela Schulz
- Department of Paediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mikel Aristorena
- UCL MRC Laboratory for Molecular Cell Biology and UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Nicole Miller
- Global Scientific Affairs, BioMarin Pharmaceutical Inc, Novato, California
| | - Sara E Mole
- UCL MRC Laboratory for Molecular Cell Biology and UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| |
Collapse
|
16
|
Smith PK, Sen MG, Fisher PR, Annesley SJ. Modelling of Neuronal Ceroid Lipofuscinosis Type 2 in Dictyostelium discoideum Suggests That Cytopathological Outcomes Result from Altered TOR Signalling. Cells 2019; 8:cells8050469. [PMID: 31100984 PMCID: PMC6562681 DOI: 10.3390/cells8050469] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/13/2019] [Accepted: 05/14/2019] [Indexed: 01/06/2023] Open
Abstract
The neuronal ceroid lipofuscinoses comprise a group of neurodegenerative disorders with similar clinical manifestations whose precise mechanisms of disease are presently unknown. We created multiple cell lines each with different levels of reduction of expression of the gene coding for the type 2 variant of the disease, Tripeptidyl peptidase (Tpp1), in the cellular slime mould Dictyostelium discoideum. Knocking down Tpp1 in Dictyostelium resulted in the accumulation of autofluorescent material, a characteristic trait of Batten disease. Phenotypic characterisation of the mutants revealed phenotypic deficiencies in growth and development, whilst endocytic uptake of nutrients was enhanced. Furthermore, the severity of the phenotypes correlated with the expression levels of Tpp1. We propose that the phenotypic defects are due to altered Target of Rapamycin (TOR) signalling. We show that treatment of wild type Dictyostelium cells with rapamycin (a specific TOR complex inhibitor) or antisense inhibition of expression of Rheb (Ras homologue enriched in the brain) (an upstream TOR complex activator) phenocopied the Tpp1 mutants. We also show that overexpression of Rheb rescued the defects caused by antisense inhibition of Tpp1. These results suggest that the TOR signalling pathway is responsible for the cytopathological outcomes in the Dictyostelium Tpp1 model of Batten disease.
Collapse
Affiliation(s)
- Paige K Smith
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora 3086, Melbourne, Australia.
| | - Melodi G Sen
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora 3086, Melbourne, Australia.
| | - Paul R Fisher
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora 3086, Melbourne, Australia.
| | - Sarah J Annesley
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora 3086, Melbourne, Australia.
| |
Collapse
|
17
|
Huber RJ, Mathavarajah S. Comparative transcriptomics reveals mechanisms underlying cln3-deficiency phenotypes in Dictyostelium. Cell Signal 2019; 58:79-90. [PMID: 30771446 DOI: 10.1016/j.cellsig.2019.02.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/29/2019] [Accepted: 02/09/2019] [Indexed: 12/28/2022]
Abstract
Mutations in CLN3 cause a juvenile form of neuronal ceroid lipofuscinosis (NCL). This devastating neurological disorder, commonly known as Batten disease, is currently untreatable due to a lack of understanding of the physiological role of the protein. Recently, work in the social amoeba Dictyostelium discoideum has provided valuable new insight into the function of CLN3 in the cell. More specifically, research has linked the Dictyostelium homolog (gene: cln3, protein: Cln3) to protein secretion, adhesion, and aggregation during starvation, which initiates multicellular development. In this study, we used comparative transcriptomics to explore the mechanisms underlying the aberrant response of cln3- cells to starvation. During starvation, 1153 genes were differentially expressed in cln3- cells compared to WT. Among the differentially expressed genes were homologs of other human NCL genes including TPP1/CLN2, CLN5, CTSD/CLN10, PGRN/CLN11, and CTSF/CLN13. STRING and GO term analyses revealed an enrichment of genes linked to metabolic, biosynthetic, and catalytic processes. We then coupled the findings from the RNA-seq analysis to biochemical assays, specifically showing that loss of cln3 affects the expression and activity of lysosomal enzymes, increases endo-lysosomal pH, and alters nitric oxide homeostasis. Finally, we show that cln3- cells accumulate autofluorescent storage bodies during starvation and provide evidence linking the function of Cln3 to Tpp1 and CtsD activity. In total, this study enhances our knowledge of the molecular mechanisms underlying Cln3 function in Dictyostelium.
Collapse
Affiliation(s)
- Robert J Huber
- Department of Biology, Trent University, Peterborough, Ontario, Canada.
| | | |
Collapse
|
18
|
McLaren MD, Mathavarajah S, Huber RJ. Recent Insights into NCL Protein Function Using the Model Organism Dictyostelium discoideum. Cells 2019; 8:cells8020115. [PMID: 30717401 PMCID: PMC6406579 DOI: 10.3390/cells8020115] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 01/26/2019] [Accepted: 01/30/2019] [Indexed: 12/16/2022] Open
Abstract
The neuronal ceroid lipofuscinoses (NCLs) are a group of devastating neurological disorders that have a global distribution and affect people of all ages. Commonly known as Batten disease, this form of neurodegeneration is linked to mutations in 13 genetically distinct genes. The precise mechanisms underlying the disease are unknown, in large part due to our poor understanding of the functions of NCL proteins. The social amoeba Dictyostelium discoideum has proven to be an exceptional model organism for studying a wide range of neurological disorders, including the NCLs. The Dictyostelium genome contains homologs of 11 of the 13 NCL genes. Its life cycle, comprised of both single-cell and multicellular phases, provides an excellent system for studying the effects of NCL gene deficiency on conserved cellular and developmental processes. In this review, we highlight recent advances in NCL research using Dictyostelium as a biomedical model.
Collapse
Affiliation(s)
- Meagan D McLaren
- Department of Biology, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada.
| | - Sabateeshan Mathavarajah
- Department of Biology, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada.
| | - Robert J Huber
- Department of Biology, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada.
| |
Collapse
|
19
|
Müller R, Stumpf M, Wehrstedt R, Sukumaran SK, Karow MA, Marko M, Noegel AA, Eichinger L. The regulatory subunit phr2AB of Dictyostelium discoideum phosphatase PP2A interacts with the centrosomal protein CEP161, a CDK5RAP2 ortholog. Genes Cells 2018; 23:923-931. [PMID: 30133996 DOI: 10.1111/gtc.12637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 08/09/2018] [Accepted: 08/09/2018] [Indexed: 11/29/2022]
Abstract
phr2AB is the regulatory subunit of the Dictyostelium discoideum phosphatase PP2A and is the ortholog of the human B55 regulatory subunit of PP2A. phr2AB was isolated as a binding partner of the centrosomal protein CEP161, an ortholog of mammalian CDK5RAP2. CEP161 is presumably a phosphoprotein and a component of the Hippo pathway. The interaction site was located in the N-terminal half of CEP161 which encompasses the γTURC binding domain in CEP161. This binding domain is responsible for binding of the γ-tubulin ring complex which allows microtubule nucleation at the centrosome. GFP-tagged phr2AB is diffusely distributed throughout the cell and enriched at the centrosome. Ectopic expression of phr2AB as GFP fusion protein led to multinucleation, aberrant nucleus centrosome ratios and an altered sensitivity to okadaic acid. Some of these features were also affected in cells over-expressing domains of CEP161 and in cells from patients suffering from primary microcephaly, which carried a mutated CDK5RAP2 gene.
Collapse
Affiliation(s)
- Rolf Müller
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Maria Stumpf
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Regina Wehrstedt
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Salil K Sukumaran
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Malte A Karow
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Marija Marko
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Angelika A Noegel
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| | - Ludwig Eichinger
- Institute for Biochemistry I, Medical Faculty, University Hospital Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne and Cologne Cluster on Cellular Stress Responses in Aging-Associated Diseases, Medical Faculty, University of Cologne, Cologne, Germany
| |
Collapse
|
20
|
Huber RJ, Mathavarajah S. Secretion and function of Cln5 during the early stages of Dictyostelium development. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2018; 1865:1437-1450. [PMID: 30048658 DOI: 10.1016/j.bbamcr.2018.07.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/18/2018] [Accepted: 07/19/2018] [Indexed: 01/05/2023]
Abstract
Mutations in CLN5 cause neuronal ceroid lipofuscinosis (NCL), a currently untreatable neurodegenerative disorder commonly known as Batten disease. Several genetic models have been generated to study the function of CLN5, but one limitation has been the lack of a homolog in lower eukaryotic model systems. Our previous work revealed a homolog of CLN5 in the social amoeba Dictyostelium discoideum. We used a Cln5-GFP fusion protein to show that the protein is secreted and functions as a glycoside hydrolase in Dictyostelium. Importantly, we also revealed this to be the molecular function of human CLN5. In this study, we generated an antibody against Cln5 to show that the endogenous protein is secreted during the early stages of Dictyostelium development. Like human CLN5, the Dictyostelium homolog is glycosylated and requires this post-translational modification for secretion. Cln5 secretion bypasses the Golgi complex, and instead, occurs via an unconventional pathway linked to autophagy. Interestingly, we observed co-localization of Cln5 and GFP-Cln3 as well as increased secretion of Cln5 and Cln5-GFP in cln3- cells. Loss of Cln5 causes defects in adhesion and chemotaxis, which intriguingly, has also been reported for Dictyostelium cells lacking Cln3. Finally, autofluorescence was detected in cln5- cells, which is consistent with observations in mammalian systems. Together, our data support a function for Cln5 during the early stages of multicellular development, provide further evidence for the molecular networking of NCL proteins, and provide insight into the mechanisms that may underlie CLN5 function in humans.
Collapse
Affiliation(s)
- Robert J Huber
- Department of Biology, Trent University, Peterborough, Ontario, Canada.
| | | |
Collapse
|
21
|
Huber RJ, Mathavarajah S. Cln5 is secreted and functions as a glycoside hydrolase in Dictyostelium. Cell Signal 2018; 42:236-248. [PMID: 29128403 DOI: 10.1016/j.cellsig.2017.11.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/24/2017] [Accepted: 11/04/2017] [Indexed: 12/15/2022]
Abstract
Ceroid lipofuscinosis neuronal 5 (CLN5) is a member of a family of proteins that are linked to neuronal ceroid lipofuscinosis (NCL). This devastating neurological disorder, known commonly as Batten disease, affects all ages and ethnicities and is currently incurable. The precise function of CLN5, like many of the NCL proteins, remains to be elucidated. In this study, we report the localization, molecular function, and interactome of Cln5, the CLN5 homolog in the social amoeba Dictyostelium discoideum. Residues that are glycosylated in human CLN5 are conserved in the Dictyostelium homolog as are residues that are mutated in patients with CLN5 disease. Dictyostelium Cln5 contains a putative signal peptide for secretion and we show that the protein is secreted during growth and starvation. We also reveal that both Dictyostelium Cln5 and human CLN5 are glycoside hydrolases, providing the first evidence in any system linking a molecular function to CLN5. Finally, immunoprecipitation coupled with mass spectrometry identified 61 proteins that interact with Cln5 in Dictyostelium. Of the 61 proteins, 67% localize to the extracellular space, 28% to intracellular vesicles, and 20% to lysosomes. A GO term enrichment analysis revealed that a majority of the interacting proteins are involved in metabolism, catabolism, proteolysis, and hydrolysis, and include other NCL-like proteins (e.g., Tpp1/Cln2, cathepsin D/Cln10, cathepsin F/Cln13) as well as proteins linked to Cln3 function in Dictyostelium (e.g., AprA, CfaD, CadA). In total, this work reveals a CLN5 homolog in Dictyostelium and further establishes this organism as a complementary model system for studying the functions of proteins linked to NCL in humans.
Collapse
Affiliation(s)
- Robert J Huber
- Trent University, Department of Biology, 1600 West Bank Drive, Peterborough, Ontario K9L 0G2, Canada.
| | - Sabateeshan Mathavarajah
- Trent University, Department of Biology, 1600 West Bank Drive, Peterborough, Ontario K9L 0G2, Canada.
| |
Collapse
|