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Yamamiya K, Li X, Nabeka H, Khan S, Khan F, Wakisaka H, Saito S, Hamada F, Matsuda S. Tracking of Prosaposin, a Saposin Precursor, in Rat Testis. J Histochem Cytochem 2023; 71:537-554. [PMID: 37728096 PMCID: PMC10546980 DOI: 10.1369/00221554231198570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/02/2023] [Indexed: 09/21/2023] Open
Abstract
We tracked prosaposin (PSAP), a trophic factor, using an antibody specific to its proteolytic portion and an antibody to sortilin that traffics PSAP only to the lysosome. Immunostaining revealed that PSAP was distributed mainly on the basal side of seminiferous tubules, where many Sertoli cells and pachytene spermatocytes contained PSAP and its distribution differed depending on the stage of the spermatogenic cycle. The PSAP-sortilin complex was sorted to large lysosomes in the basal cytoplasm of Sertoli cells, where it may be processed into saposins. In contrast, in the thinner apical cytoplasm of Sertoli cells, PSAP in small lysosomes was transported to the apical side around sperm heads or into the lumen for secretion. The results of in situ hybridization analyses suggested that immature tubular cells in young animals produce PSAP to self-stimulate proliferation. However, in adults, not only Sertoli cells but also pachytene spermatocytes produce and secrete PSAP around germ cells or into the tubular lumen to stimulate cell proliferation or differentiation in a paracrine or autocrine manner. In summary, PSAP is not only a precursor of lysosomal enzymes but also a pivotal trophic factor in organogenesis in the immature testis and spermatogenesis in the mature testis.
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Affiliation(s)
| | - Xuan Li
- Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang, China
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Taniguchi M, Nabeka H, Yamamiya K, Khan MSI, Shimokawa T, Islam F, Doihara T, Wakisaka H, Kobayashi N, Hamada F, Matsuda S. The expression of prosaposin and its receptors, GRP37 and GPR37L1, are increased in the developing dorsal root ganglion. PLoS One 2021; 16:e0255958. [PMID: 34379697 PMCID: PMC8357083 DOI: 10.1371/journal.pone.0255958] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 07/27/2021] [Indexed: 11/18/2022] Open
Abstract
Prosaposin (PSAP), a highly conserved glycoprotein, is a precursor of saposins A-D. Accumulating evidence suggests that PSAP is a neurotrophic factor, as well as a regulator of lysosomal enzymes. Recently, the orphan G-protein-coupled receptors GPR37 and GPR37L1 were recognized as PSAP receptors, but their functions have not yet been clarified. In this study, we examined the distribution of PSAP and its receptors in the dorsal root ganglion (DRG) during development using specific antibodies, and showed that PSAP accumulates primarily in lysosomes and is dispersed throughout the cytoplasm of satellite cells. Later, PSAP colocalized with two receptors in satellite cells, and formed a characteristic ring shape approximately 8 weeks after birth, during a period of rapid DRG development. This ring shape, which was only observed around larger neurons, is evidence that several satellite cells are synchronously activated. We found that sortilin, a transporter of a wide variety of intracellular proteins containing PSAP, is strongly localized to the inner side of satellite cells, which contact the neuronal surface. These findings suggest that PSAP and GPR37/GPR37L1 play a role in activating both satellite and nerve cells.
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Affiliation(s)
- Miho Taniguchi
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Hiroaki Nabeka
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Kimiko Yamamiya
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Md Sakirul Islam Khan
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Tetsuya Shimokawa
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Farzana Islam
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Takuya Doihara
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Hiroyuki Wakisaka
- Department of Otorhinolaryngology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Naoto Kobayashi
- Department of Medical Education Center, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Fumihiko Hamada
- Department of Human Anatomy, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Seiji Matsuda
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
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Ługowska A, Hetmańczyk-Sawicka K, Iwanicka-Nowicka R, Fogtman A, Cieśla J, Purzycka-Olewiecka JK, Sitarska D, Płoski R, Filocamo M, Lualdi S, Bednarska-Makaruk M, Koblowska M. Gene expression profile in patients with Gaucher disease indicates activation of inflammatory processes. Sci Rep 2019; 9:6060. [PMID: 30988500 PMCID: PMC6465595 DOI: 10.1038/s41598-019-42584-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 04/01/2019] [Indexed: 01/26/2023] Open
Abstract
Gaucher disease (GD) is a rare inherited metabolic disease caused by pathogenic variants in the GBA1 gene. So far, the pathomechanism of GD was investigated mainly in animal models. In order to delineate the molecular changes in GD cells we analysed gene expression profile in cultured skin fibroblasts from GD patients, control individuals and, additionally, patients with Niemann-Pick type C disease (NPC). We used expression microarrays with subsequent validation by qRT-PCR method. In the comparison GD patients vs. controls, the most pronounced relative fold change (rFC) in expression was observed for genes IL13RA2 and IFI6 (up-regulated) and ATOH8 and CRISPLD2 (down-regulated). Products of up-regulated and down-regulated genes were both enriched in genes associated with immune response. In addition, products of down-regulated genes were associated with cell-to-cell and cell-to-matrix interactions, matrix remodelling, PI3K-Akt signalling pathway and a neuronal survival pathway. Up-regulation of PLAU, IFIT1, TMEM158 and down-regulation of ATOH8 and ISLR distinguished GD patients from both NPC patients and healthy controls. Our results emphasize the inflammatory character of changes occurring in human GD cells indicating that further studies on novel therapeutics for GD should consider anti-inflammatory agents.
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Affiliation(s)
- Agnieszka Ługowska
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland.
| | | | - Roksana Iwanicka-Nowicka
- Laboratory of Microarray Analysis, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
- Laboratory of Systems Biology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Anna Fogtman
- Laboratory of Microarray Analysis, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Jarosław Cieśla
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | | | - Dominika Sitarska
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Rafał Płoski
- Department of Medical Genetics, Warsaw Medical University, Warsaw, Poland
| | - Mirella Filocamo
- Laboratorio di Genetica Molecolare e Biobanche, Istituto G. Gaslini, L.go G. Gaslini -16147, Genova, Italy
| | - Susanna Lualdi
- Laboratorio di Genetica Molecolare e Biobanche, Istituto G. Gaslini, L.go G. Gaslini -16147, Genova, Italy
| | | | - Marta Koblowska
- Laboratory of Microarray Analysis, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
- Laboratory of Systems Biology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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Zhou X, Paushter DH, Feng T, Sun L, Reinheckel T, Hu F. Lysosomal processing of progranulin. Mol Neurodegener 2017; 12:62. [PMID: 28835281 PMCID: PMC5569495 DOI: 10.1186/s13024-017-0205-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/15/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutations resulting in progranulin (PGRN) haploinsufficiency cause frontotemporal lobar degeneration with TDP-43-positive inclusions (FTLD-TDP), a devastating neurodegenerative disease. PGRN is localized to the lysosome and important for proper lysosome function. However, the metabolism of PGRN in the lysosome is still unclear. RESULTS Here, we report that PGRN is processed into ~10 kDa peptides intracellularly in multiple cell types and tissues and this processing is dependent on lysosomal activities. PGRN endocytosed from the extracellular space is also processed in a similar manner. We further demonstrated that multiple cathepsins are involved in PGRN processing and cathepsin L cleaves PGRN in vitro. CONCLUSIONS Our data support that PGRN is processed in the lysosome through the actions of cathepsins.
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Affiliation(s)
- Xiaolai Zhou
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Daniel H Paushter
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Tuancheng Feng
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Lirong Sun
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA.,Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Thomas Reinheckel
- Institute of Molecular Medicine and Cell Research, Medical Faculty and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, 79104, Freiburg, Germany
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA.
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Nabeka H, Saito S, Li X, Shimokawa T, Khan MSI, Yamamiya K, Kawabe S, Doihara T, Hamada F, Kobayashi N, Matsuda S. Interneurons secrete prosaposin, a neurotrophic factor, to attenuate kainic acid-induced neurotoxicity. IBRO Rep 2017; 3:17-32. [PMID: 30135939 PMCID: PMC6084830 DOI: 10.1016/j.ibror.2017.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 07/16/2017] [Accepted: 07/21/2017] [Indexed: 12/30/2022] Open
Abstract
PS increased mainly in the axons of PV positive interneurons after kainic acid (KA) injection. Electron microscopy revealed PS containing vesicles in PV positive axons. PS is secreted with secretogranin from synapses. The increased PS in the interneurons was due to increases in PS + 0, as in the choroid plexus. Interneurons produce and secrete intact PS around the hippocampal pyramidal neurons to protect them from KA neurotoxicity.
Prosaposin (PS) is a secretory neurotrophic factor, as well as a regulator of lysosomal enzymes. We previously reported the up-regulation of PS and the possibility of its axonal transport by GABAergic interneurons after exocitotoxicity induced by kainic acid (KA), a glutamate analog. In the present study, we performed double immunostaining with PS and three calcium binding protein markers: parvalbumin (PV), calbindin, and calretinin, for the subpopulation of GABAergic interneurons, and clarified that the increased PS around the hippocampal pyramidal neurons after KA injection existed mainly in the axons of PV positive interneurons. Electron microscopy revealed PS containing vesicles in the PV positive axon. Double immunostaining with PS and secretogranin or synapsin suggested that PS is secreted with secretogranin from synapses. Based on the results from in situ hybridization with two alternative splicing forms of PS mRNA, the increase of PS in the interneurons was due to the increase of PS + 0 (mRNA without 9-base insertion) as in the choroid plexus, but not PS + 9 (mRNA with 9-base insertion). These results were similar to those from the choroid plexus, which secretes an intact form PS + 0 to the cerebrospinal fluid. Neurons, especially PV positive GABAergic interneurons, produce and secrete the intact form of PS around hippocampal pyramidal neurons to protect them against KA neurotoxicity.
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Affiliation(s)
- Hiroaki Nabeka
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Shouichiro Saito
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, Yanagido, Gifu, Japan
| | - Xuan Li
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Tetsuya Shimokawa
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Md Sakirul Islam Khan
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Kimiko Yamamiya
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | | | - Takuya Doihara
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Fumihiko Hamada
- Department of Human Anatomy, Oita University Fuculty of Medicine, Yufu, Oita, Japan
| | - Naoto Kobayashi
- Medical Education Center, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Seiji Matsuda
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
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Zhou X, Sullivan PM, Sun L, Hu F. The interaction between progranulin and prosaposin is mediated by granulins and the linker region between saposin B and C. J Neurochem 2017. [PMID: 28640985 DOI: 10.1111/jnc.14110] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The frontotemporal lobar degeneration (FTLD) protein progranulin (PGRN) is essential for proper lysosomal function. PGRN localizes in the lysosomal compartment within the cell. Prosaposin (PSAP), the precursor of lysosomal saposin activators (saposin A, B, C, D), physically interacts with PGRN. Previously, we have shown that PGRN and PSAP facilitate each other's lysosomal trafficking. Here, we report that the interaction between PSAP and PGRN requires the linker region of saposin B and C (BC linker). PSAP protein with the BC linker mutated, fails to interact with PGRN and deliver PGRN to lysosomes in the biosynthetic and endocytic pathways. On the other hand, PGRN interacts with PSAP through multiple granulin motifs. Granulin D and E bind to PSAP with similar affinity as full-length PGRN. Read the Editorial Comment for this article on page 154.
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Affiliation(s)
- Xiaolai Zhou
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
| | - Peter M Sullivan
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
| | - Lirong Sun
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
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Impaired prosaposin lysosomal trafficking in frontotemporal lobar degeneration due to progranulin mutations. Nat Commun 2017; 8:15277. [PMID: 28541286 PMCID: PMC5477518 DOI: 10.1038/ncomms15277] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 03/15/2017] [Indexed: 01/01/2023] Open
Abstract
Haploinsufficiency of progranulin (PGRN) due to mutations in the granulin (GRN) gene causes frontotemporal lobar degeneration (FTLD), and complete loss of PGRN leads to a lysosomal storage disorder, neuronal ceroid lipofuscinosis (NCL). Accumulating evidence suggests that PGRN is essential for proper lysosomal function, but the precise mechanisms involved are not known. Here, we show that PGRN facilitates neuronal uptake and lysosomal delivery of prosaposin (PSAP), the precursor of saposin peptides that are essential for lysosomal glycosphingolipid degradation. We found reduced levels of PSAP in neurons both in mice deficient in PGRN and in human samples from FTLD patients due to GRN mutations. Furthermore, mice with reduced PSAP expression demonstrated FTLD-like pathology and behavioural changes. Thus, our data demonstrate a role of PGRN in PSAP lysosomal trafficking and suggest that impaired lysosomal trafficking of PSAP is an underlying disease mechanism for NCL and FTLD due to GRN mutations. Mutations in the granulin gene are associated with frontotemporal lobe dementia (FTLD) and a lysosomal storage disease. The authors show that reduced progranulin levels leads to impaired neuronal uptake and lysosomal delivery of prosaposin, and that decreased prosaposin expression in mice leads to FTLD-like behaviour.
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Li X, Nabeka H, Saito S, Shimokawa T, Khan MSI, Yamamiya K, Shan F, Gao H, Li C, Matsuda S. Expression of prosaposin and its receptors in the rat cerebellum after kainic acid injection. IBRO Rep 2017; 2:31-40. [PMID: 30135931 PMCID: PMC6084904 DOI: 10.1016/j.ibror.2017.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/02/2017] [Accepted: 02/21/2017] [Indexed: 11/16/2022] Open
Abstract
Prosaposin (PSAP), a highly conserved glycoprotein, is a precursor of saposins A–D. Accumulating evidence suggests that PSAP is a neurotrophic factor that induces differentiation and prevents death in a variety of neuronal cells through the active region within the saposin C domain both in vivo and in vitro. Recently, GPR37 and GPR37L1 were recognized as PSAP receptors. In this study, we examined the alteration in expression of PSAP and its receptors in the cerebellum using rats injected with kainic acid (KA). The results show that PSAP was strongly expressed in the cytoplasm of Purkinje cells and interneurons in the molecular layer, and that PSAP expression in both types of neurons was markedly enhanced following KA treatment. Immunoblotting revealed that the expression of GPR37 was diminished significantly three days after KA injection compared with control rats; however, no changes were observed through immunostaining. No discernable changes were found in GPR37L1. These findings may help us to understand the role of PSAP and the GPR37 and GPR37L1 receptors in alleviating the neural damage caused by KA.
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Key Words
- BSA, bovine serum albumin
- Cerebellum
- ER, endoplasmic reticulum
- GPCR, G protein-coupled receptor
- GPR37
- GPR37L1
- H-E staining, hematoxylin-eosin staining
- IF, immunofluorescence
- IHC, immunohistochemistry
- ISH, in situ hybridization
- KA, kainic acid
- Kainic acid
- Neurodegeneration
- PSAP, prosaposin
- Prosaposin
- SSC, standard saline citrate
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Affiliation(s)
- Xuan Li
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Hiroaki Nabeka
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Shouichiro Saito
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, Yanagido, Gifu, Japan
| | - Tetsuya Shimokawa
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Md Sakirul Islam Khan
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Kimiko Yamamiya
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Fengping Shan
- Department of Immunology, School of Basic Medical Science, China Medical University, Shenyang, PR China
| | - Huiling Gao
- College of Life and Health Science, Northeastern University, Shenyang, PR China
| | - Cheng Li
- Department of Immunology, School of Basic Medical Science, China Medical University, Shenyang, PR China
| | - Seiji Matsuda
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
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Abdul-Hammed M, Breiden B, Schwarzmann G, Sandhoff K. Lipids regulate the hydrolysis of membrane bound glucosylceramide by lysosomal β-glucocerebrosidase. J Lipid Res 2017; 58:563-577. [PMID: 28126847 DOI: 10.1194/jlr.m073510] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/24/2017] [Indexed: 01/24/2023] Open
Abstract
Glucosylceramide (GlcCer) is the primary storage lipid in the lysosomes of Gaucher patients and a secondary one in Niemann-Pick disease types A, B, and C. The regulatory roles of lipids on the hydrolysis of membrane bound GlcCer by lysosomal β-glucocerebrosidase (GBA1) was probed using a detergent-free liposomal assay. The degradation rarely occurs at uncharged liposomal surfaces in the absence of saposin (Sap) C. However, anionic lipids stimulate GlcCer hydrolysis at low pH by up to 1,000-fold depending on the nature and position of the negative charges in their head groups while cationic lipids inhibit the degradation, thus showing the importance of electrostatic interactions between the polycationic GBA1 and the negatively charged vesicle surfaces at low pH. Ceramide, fatty acids, monoacylglycerol, and diacylglycerol also stimulate GlcCer hydrolysis while SM, sphingosine, and sphinganine play strong inhibitory roles, thereby explaining the secondary storage of GlcCer in Niemann-Pick diseases. Surprisingly, cholesterol stimulates GlcCer degradation in the presence of bis(monoacylglycero)phosphate (BMP). Sap C strongly stimulates GlcCer hydrolysis even in the absence of BMP and the regulatory roles of the intraendolysosomal lipids on its activity is discussed. Our data suggest that these strong modifiers of GlcCer hydrolysis affect the genotype-phenotype correlation in several cases of Gaucher patients independent of the types.
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Affiliation(s)
- Misbaudeen Abdul-Hammed
- Life and Medical Sciences (LIMES) Institut, Membrane Biology and Lipid Biochemistry Unit, Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Bonn, Germany.,Biophysical Chemistry Group, Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Bernadette Breiden
- Life and Medical Sciences (LIMES) Institut, Membrane Biology and Lipid Biochemistry Unit, Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Bonn, Germany
| | - Günter Schwarzmann
- Life and Medical Sciences (LIMES) Institut, Membrane Biology and Lipid Biochemistry Unit, Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Bonn, Germany
| | - Konrad Sandhoff
- Life and Medical Sciences (LIMES) Institut, Membrane Biology and Lipid Biochemistry Unit, Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Bonn, Germany
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Serratrice C, Carballo S, Serratrice J, Stirnemann J. Imiglucerase in the management of Gaucher disease type 1: an evidence-based review of its place in therapy. CORE EVIDENCE 2016; 11:37-47. [PMID: 27790078 PMCID: PMC5072572 DOI: 10.2147/ce.s93717] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Introduction Gaucher disease is the first lysosomal disease to benefit from enzyme replacement therapy, thus serving as model for numerous other lysosomal diseases. Alglucerase was the first glucocerebrosidase purified from placental extracts, and this was then replaced by imiglucerase – a Chinese hamster ovary cell-derived glucocerebrosidase. Aim The aim was to review the evidence underlying the use of imiglucerase in Gaucher disease type 1 Evidence review Data from clinical trials and Gaucher Registries were analyzed. Conclusion Imiglucerase has been prescribed and found to have an excellent efficacy and safety profile. We report herein the evidence-based data published for 26 years justifying the use of imiglucerase.
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Affiliation(s)
- Christine Serratrice
- Department of Internal Medicine and Rehabilitation, Geneva University Hospital, Thonex, Switzerland
| | - Sebastian Carballo
- Department of General Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Jacques Serratrice
- Department of General Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Jérome Stirnemann
- Department of General Internal Medicine, Geneva University Hospital, Geneva, Switzerland
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11
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Blanz J, Saftig P. Parkinson's disease: acid-glucocerebrosidase activity and alpha-synuclein clearance. J Neurochem 2016; 139 Suppl 1:198-215. [PMID: 26860955 DOI: 10.1111/jnc.13517] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 12/07/2015] [Accepted: 12/09/2015] [Indexed: 12/27/2022]
Abstract
The role of mutations in the gene GBA1 encoding the lysosomal hydrolase β-glucocerebrosidase for the development of synucleinopathies, such as Parkinson's disease and dementia with Lewy bodies, was only very recently uncovered. The knowledge obtained from the study of carriers or patients suffering from Gaucher disease (a common lysosomal storage disorder because of GBA1 mutations) is of particular importance for understanding the role of the enzyme and its catabolic pathway in the development of synucleinopathies. Decreased activity of β-glucocerebrosidase leads to lysosomal dysfunction and the accumulation of its substrate glucosylceramide and related lipid derivatives. Glucosylceramide is suggested to stabilize toxic oligomeric forms of α-synuclein that negatively influence the activity of β-glucocerebrosidase and to partially block export of newly synthesized β-glucocerebrosidase from the endoplasmic reticulum to late endocytic compartments, amplifying the pathological effects of α-synuclein and ultimately resulting in neuronal cell death. This pathogenic molecular feedback loop and most likely other factors (such as impaired endoplasmic reticulum-associated degradation, activation of the unfolded protein response and dysregulation of calcium homeostasis induced by misfolded GC mutants) are involved in shifting the cellular homeostasis from monomeric α-synuclein towards oligomeric neurotoxic and aggregated forms, which contribute to Parkinson's disease progression. From a therapeutic point of view, strategies aiming to increase either the expression, stability or delivery of the β-glucocerebrosidase to lysosomes are likely to decrease the α-synuclein burden and may be useful for an in depth evaluation at the organismal level. Lysosomes are critical for protein and lipid homeostasis. Recent research revealed that dysfunction of this organelle contributes to the development of neurodegenerative diseases such as Parkinson's disease (PD). Mutations in the lysosomal hydrolase β-glucocerebrosidase (GBA1) are a major risk factor for the development of PD and the molecular events linked to the reduced activity of GBA1 and the pathological accumulation of lipids and α-synuclein are just at the beginning to be understood. New therapeutic concepts in regards to how to increase the expression, stability, or delivery of β-glucocerebrosidase to lysosomes are currently developed. This article is part of a special issue on Parkinson disease.
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Affiliation(s)
- Judith Blanz
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Paul Saftig
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
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Zhou X, Sun L, Bastos de Oliveira F, Qi X, Brown WJ, Smolka MB, Sun Y, Hu F. Prosaposin facilitates sortilin-independent lysosomal trafficking of progranulin. J Cell Biol 2015; 210:991-1002. [PMID: 26370502 PMCID: PMC4576858 DOI: 10.1083/jcb.201502029] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Prosaposin directly interacts with progranulin and facilitates progranulin lysosomal trafficking via the trafficking receptors M6PR and LRP1, independent of the previously identified progranulin trafficking pathway mediated by sortilin. Mutations in the progranulin (PGRN) gene have been linked to two distinct neurodegenerative diseases, frontotemporal lobar degeneration (FTLD) and neuronal ceroid lipofuscinosis (NCL). Accumulating evidence suggests a critical role of PGRN in lysosomes. However, how PGRN is trafficked to lysosomes is still not clear. Here we report a novel pathway for lysosomal delivery of PGRN. We found that prosaposin (PSAP) interacts with PGRN and facilitates its lysosomal targeting in both biosynthetic and endocytic pathways via the cation-independent mannose 6-phosphate receptor and low density lipoprotein receptor-related protein 1. PSAP deficiency in mice leads to severe PGRN trafficking defects and a drastic increase in serum PGRN levels. We further showed that this PSAP pathway is independent of, but complementary to, the previously identified PGRN lysosomal trafficking mediated by sortilin. Collectively, our results provide new understanding on PGRN trafficking and shed light on the molecular mechanisms behind FTLD and NCL caused by PGRN mutations.
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Affiliation(s)
- Xiaolai Zhou
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Lirong Sun
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853 Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Francisco Bastos de Oliveira
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Xiaoyang Qi
- Division of Hematology and Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45229
| | - William J Brown
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Ying Sun
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
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Nabeka H, Uematsu K, Takechi H, Shimokawa T, Yamamiya K, Li C, Doihara T, Saito S, Kobayashi N, Matsuda S. Prosaposin overexpression following kainic acid-induced neurotoxicity. PLoS One 2014; 9:e110534. [PMID: 25461957 PMCID: PMC4251898 DOI: 10.1371/journal.pone.0110534] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 09/18/2014] [Indexed: 12/21/2022] Open
Abstract
Because excessive glutamate release is believed to play a pivotal role in numerous neuropathological disorders, such as ischemia or seizure, we aimed to investigate whether intrinsic prosaposin (PS), a neuroprotective factor when supplied exogenously in vivo or in vitro, is up-regulated after the excitotoxicity induced by kainic acid (KA), a glutamate analog. In the present study, PS immunoreactivity and its mRNA expression in the hippocampal and cortical neurons showed significant increases on day 3 after KA injection, and high PS levels were maintained even after 3 weeks. The increase in PS, but not saposins, detected by immunoblot analysis suggests that the increase in PS-like immunoreactivity after KA injection was not due to an increase in saposins as lysosomal enzymes after neuronal damage, but rather to an increase in PS as a neurotrophic factor to improve neuronal survival. Furthermore, several neurons with slender nuclei inside/outside of the pyramidal layer showed more intense PS mRNA expression than other pyramidal neurons. Based on the results from double immunostaining using anti-PS and anti-GABA antibodies, these neurons were shown to be GABAergic interneurons in the extra- and intra-pyramidal layers. In the cerebral cortex, several large neurons in the V layer showed very intense PS mRNA expression 3 days after KA injection. The choroid plexus showed intense PS mRNA expression even in the normal rat, and the intensity increased significantly after KA injection. The present study indicates that inhibitory interneurons as well as stimulated hippocampal pyramidal and cortical neurons synthesize PS for neuronal survival, and the choroid plexus is highly activated to synthesize PS, which may prevent neurons from excitotoxic neuronal damage. To the best of our knowledge, this is the first study that demonstrates axonal transport and increased production of neurotrophic factor PS after KA injection.
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Affiliation(s)
- Hiroaki Nabeka
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Keigo Uematsu
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Hiroko Takechi
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Tetsuya Shimokawa
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
- * E-mail:
| | - Kimiko Yamamiya
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Cheng Li
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Takuya Doihara
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Shouichiro Saito
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, Yanagido, Gifu, Japan
| | - Naoto Kobayashi
- Medical Education Center, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Seiji Matsuda
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
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Shimokawa T, Nabeka H, Yamamiya K, Wakisaka H, Takeuchi T, Kobayashi N, Matsuda S. Distribution of prosaposin in rat lymphatic tissues. Cell Tissue Res 2013; 352:685-93. [PMID: 23420452 DOI: 10.1007/s00441-013-1575-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 01/17/2013] [Indexed: 11/26/2022]
Abstract
Prosaposin (PSAP) is as a trophic factor and an activator protein for sphingolipid hydrolase in lysosomes. We generated a specific antibody to PSAP and examined the spatiotemporal distribution of PSAP-immunoreactive (PSAP-IR) cells in the lymphatic tissues of Wistar rats. Immunoblots of tissue homogenates separated electrophoretically showed a single band for PSAP in brain but two bands in spleen. PSAP-IR cells were distributed in both the red and white pulp of the spleen, in both the cortex and medulla of the thymus and in mesenteric lymph nodes. Many PSAP-IR cells were found in the dome portion of Peyer's patches and the number of PSAP-IR cells increased with the age of the rat. To identify the PSAP-IR cells, double- and triple-immunostainings were performed with antibodies against PSAP, CD68 and CD1d. The large number of double- and triple-positive cells suggested that antigen-presenting cells contained much PSAP in these lymphatic tissues. Intense expression of PSAP mRNA, examined by in situ hybridisation, was observed in the red pulp and corona of the spleen. In rats, the PSAP gene generates two alternative splicing forms of mRNA: Pro+9 containing a 9-base insertion and Pro+0 without the insertion. We examined the expression patterns of the alternative splicing forms of PSAP mRNA in the spleen. The presence of both types of mRNA (Pro+9 and Pro+0) indicated that the spleen contains various types of prosaposin-producing and/or secreting cells. These findings suggest diverse functions for PSAP in the immune system.
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Affiliation(s)
- Tetsuya Shimokawa
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0212, Japan.
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Stirnemann J, Vigan M, Hamroun D, Heraoui D, Rossi-Semerano L, Berger MG, Rose C, Camou F, de Roux-Serratrice C, Grosbois B, Kaminsky P, Robert A, Caillaud C, Froissart R, Levade T, Masseau A, Mignot C, Sedel F, Dobbelaere D, Vanier MT, Valayanopoulos V, Fain O, Fantin B, de Villemeur TB, Mentré F, Belmatoug N. The French Gaucher's disease registry: clinical characteristics, complications and treatment of 562 patients. Orphanet J Rare Dis 2012; 7:77. [PMID: 23046562 PMCID: PMC3526516 DOI: 10.1186/1750-1172-7-77] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 10/07/2012] [Indexed: 02/02/2023] Open
Abstract
Background Clinical features, complications and treatments of Gaucher’s disease (GD), a rare autosomal–recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described. Methods All patients with known GD, living in France, with ≥1 consultations (1980–2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with ≥1 follow-up visits, to investigate complications; recently followed (2009–2010) patients; and patients treated during 2009–2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables. Results Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal–lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0–77) and 22 (0–84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1–67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson’s disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009–2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%–26.5%) and 19.8% (13.5%–26.1%). Conclusion This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.
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Affiliation(s)
- Jérôme Stirnemann
- INSERM, UMR 738, Laboratoire de Biostatistiques Hôpital Bichat, Assistance Publique Hôpitaux de Paris (AP-HP), Paris, France.
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Xue B, Chen J, Gao H, Saito S, Kobayashi N, Shimokawa T, Nabeka H, Sano A, Matsuda S. Chronological changes in prosaposin in the developing rat brain. Neurosci Res 2011; 71:22-34. [PMID: 21684311 DOI: 10.1016/j.neures.2011.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 05/28/2011] [Accepted: 06/01/2011] [Indexed: 11/30/2022]
Abstract
Prosaposin is the precursor protein of four glycoproteins, saposins A, B, C, and D, which activate sphingolipid hydrolases in lysosomes. Besides this role, intact prosaposin is also known as a potent neurotrophic factor that prevents neuronal cell death and stimulates neurite outgrowth in in vivo and in vitro experiments. In the present study, we examined chronological changes in prosaposin immunoreactivity in the rat brain using immunofluorescence staining and Diaminobenzidine (DAB) immunohistochemistry. In the hippocampal regions CA1, CA3, and dentate gyrus, the strongest staining of prosaposin was observed on postnatal day 1. The prosaposin immunoreactivity then decreased gradually until postnatal day 28. But in the cerebral cortex, prosaposin staining intensity increased from postnatal day 1 to 14, then decreased until postnatal day 28. The prosaposin immunoreactivity co-localized with the lysosomal granules labeled by an anti-Cathepsin D antibody, indicating that prosaposin mainly localized in the lysosomes of the neurons. We also examined the chronological changes in prosaposin mRNA and its two alternatively spliced variants using in situ hybridization. We found that both the mRNA forms, especially the one without a nine-base insertion, increased significantly from embryonic day 15 to postnatal day 7, then decreased gradually until postnatal day 28. Abundant prosaposin expression in the perinatal stages indicates a potential role of prosaposin in the early development of the rat brain.
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Affiliation(s)
- Bing Xue
- Division of Anatomy and Embryology, Department of Integrated Basic Medical Science, Ehime University School of Medicine, Shitsukawa, To-on, Ehime 791-0295, Japan
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Bone events and evolution of biologic markers in Gaucher disease before and during treatment. Arthritis Res Ther 2010; 12:R156. [PMID: 20696071 PMCID: PMC2945057 DOI: 10.1186/ar3111] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 07/21/2010] [Accepted: 08/09/2010] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION Known biomarkers of Gaucher-disease activity are platelets, chitotriosidase, angiotensin-converting enzyme (ACE), tartrate-resistant acid phosphatase (TRAP) and ferritin. The aim of this study was to retrospectively evaluate the frequency of bone events (BE) and biomarker changes during two periods: diagnosis to first enzyme-replacement therapy (ERT) and the latter to the closing date. METHODS BE of 62 treated patients, among the 73-patient cohort followed at Beaujon Hospital, Clichy, France, were described with Kaplan-Meier curves, and linear-mixed models were used to analyze their biomarker changes and the influence of several covariates (splenectomy, diagnosis year, genotype, age at diagnosis and sex). RESULTS BE occurred before (54 events in 21 patients), but also during, ERT (12 events in 10 patients), with respective frequencies (95% confidence interval) at 10 years of 22.4% (13.3 to 36.3) and 20.0% (10.2 to 36.9). Biomarker slope changes before and during ERT differed significantly for platelets (+190/mm3/year and 7,035/mm3/year, respectively; P < 0.0001) and ferritin (+4% and -14%; P < 0.0001). High ferritin levels and low platelet counts at ERT onset were significantly associated with BE during ERT (P = 0.019 and 0.039, respectively). Covariates significantly influenced biomarker changes (baseline and/or slope): splenectomy affected platelets (baseline and changes), TRAP changes and chitotriosidase changes; diagnosis date influenced ACE and TRAP baseline values; and genotype influenced chitotriosidase baseline and changes. CONCLUSIONS Platelet counts and ferritin levels and their slope changes at ERT onset seem to predict BE during treatment. Biomarker baseline values and changes are dependent on several covariables.
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18
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Sun Y, Liou B, Ran H, Skelton MR, Williams MT, Vorhees CV, Kitatani K, Hannun YA, Witte DP, Xu YH, Grabowski GA. Neuronopathic Gaucher disease in the mouse: viable combined selective saposin C deficiency and mutant glucocerebrosidase (V394L) mice with glucosylsphingosine and glucosylceramide accumulation and progressive neurological deficits. Hum Mol Genet 2010; 19:1088-97. [PMID: 20047948 PMCID: PMC2830832 DOI: 10.1093/hmg/ddp580] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Gaucher disease is caused by defective acid β-glucosidase (GCase) function. Saposin C is a lysosomal protein needed for optimal GCase activity. To test the in vivo effects of saposin C on GCase, saposin C deficient mice (C−/−) were backcrossed to point mutated GCase (V394L/V394L) mice. The resultant mice (4L;C*) began to exhibit CNS abnormalities ∼30 days: first as hindlimb paresis, then progressive tremor and ataxia. Death occurred ∼48 days due to neurological deficits. Axonal degeneration was evident in brain stem, spinal cord and white matter of cerebellum accompanied by increasing infiltration of the brain stem, cortex and thalamus by CD68 positive microglial cells and activation of astrocytes. Electron microscopy showed inclusion bodies in neuronal processes and degenerating cells. Accumulation of p62 and Lamp2 were prominent in the brain suggesting the impairment of autophagosome/lysosome function. This phenotype was different from either V394L/V394L or C−/− alone. Relative to V394L/V394L mice, 4L;C* mice had diminished GCase protein and activity. Marked increases (20- to 30-fold) of glucosylsphingosine (GS) and moderate elevation (1.5- to 3-fold) of glucosylceramide (GC) were in 4L;C* brains. Visceral tissues had increases of GS and GC, but no storage cells were found. Neuronal cells in thick hippocampal slices from 4L;C* mice had significantly attenuated long-term potentiation, presumably resulting from substrate accumulation. The 4L;C* mouse mimics the CNS phenotype and biochemistry of some type 3 (neuronopathic) variants of Gaucher disease and is a unique model suitable for testing pharmacological chaperone and substrate reduction therapies, and investigating the mechanisms of neuronopathic Gaucher disease.
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Affiliation(s)
- Ying Sun
- The Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229-3039, USA
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Sun Y, Ran H, Zamzow M, Kitatani K, Skelton MR, Williams MT, Vorhees CV, Witte DP, Hannun YA, Grabowski GA. Specific saposin C deficiency: CNS impairment and acid beta-glucosidase effects in the mouse. Hum Mol Genet 2009; 19:634-47. [PMID: 20015957 PMCID: PMC2807372 DOI: 10.1093/hmg/ddp531] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Saposins A, B, C and D are derived from a common precursor, prosaposin (psap). The few patients with saposin C deficiency develop a Gaucher disease-like central nervous system (CNS) phenotype attributed to diminished glucosylceramide (GC) cleavage activity by acid β-glucosidase (GCase). The in vivo effects of saposin C were examined by creating mice with selective absence of saposin C (C−/−) using a knock-in point mutation (cysteine-to-proline) in exon 11 of the psap gene. In C−/− mice, prosaposin and saposins A, B and D proteins were present at near wild-type levels, but the saposin C protein was absent. By 1 year, the C−/− mice exhibited weakness of the hind limbs and progressive ataxia. Decreased neuromotor activity and impaired hippocampal long-term potentiation were evident. Foamy storage cells were observed in dorsal root ganglion and there was progressive loss of cerebellar Purkinje cells and atrophy of cerebellar granule cells. Ultrastructural analyses revealed inclusions in axonal processes in the spinal cord, sciatic nerve and brain, but no excess of multivesicular bodies. Activated microglial cells and astrocytes were present in thalamus, brain stem, cerebellum and spinal cord, indicating regional pro-inflammatory responses. No storage cells were found in visceral organs of these mice. The absence of saposin C led to moderate increases in GC and lactosylceramide (LacCer) and their deacylated analogues. These results support the view that saposin C has multiple roles in glycosphingolipid (GSL) catabolism as well as a prominent function in CNS and axonal integrity independent of its role as an optimizer/stabilizer of GCase.
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Affiliation(s)
- Ying Sun
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Tylki-Szymańska A, Czartoryska B, Vanier MT, Poorthuis BJMH, Groener JAE, Ługowska A, Millat G, Vaccaro AM, Jurkiewicz E. Non-neuronopathic Gaucher disease due to saposin C deficiency. Clin Genet 2007; 72:538-42. [PMID: 17919309 DOI: 10.1111/j.1399-0004.2007.00899.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gaucher disease is generally caused by a deficiency of the lysosomal enzyme glucocerebrosidase. The degradation of glycosphingolipids requires also the participation of sphingolipid activator proteins. The prosaposin PSAP gene codes for a single protein which undergoes post-translational cleavage to yield four proteins named saposins A, B, C and D. Saposin (SAP-) C is required for glucosylceramide degradation, and its deficiency results in a variant form of Gaucher disease. In this report, we present clinical, biochemical, and molecular findings in a 36-year-old man and his 30-year-old sister with non-neuronopathic Gaucher disease due to SAP-C deficiency. Very high levels of chitotriosidase activity, chemokine CCL18, and increased concentration of glucosylceramide in plasma and normal beta-glucosidase activity in skin fibroblasts were observed in the patients. A molecular genetics study of the PSAP gene enabled the identification of one missense mutation, p.L349P, located in the SAP-C domain and another mutation, p.M1L, located in the initiation codon of the prosaposin precursor protein. The presented findings describe the first cases where the non-neuronopathic Gaucher disease has been definitely demonstrated to be a consequence of SAP-C deficiency. Three previously described cases in the literature displayed a Gaucher type 3 phenotype.
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Affiliation(s)
- A Tylki-Szymańska
- Department of Metabolic Diseases, Endocrinology, and Diabetology, The Children's Memorial Health Institute, Warsaw, Poland.
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Hosoda Y, Miyawaki K, Saito S, Chen J, Bing X, Terashita T, Kobayashi N, Araki N, Shimokawa T, Hamada F, Sano A, Tanabe H, Matsuda S. Distribution of prosaposin in the rat nervous system. Cell Tissue Res 2007; 330:197-207. [PMID: 17763872 DOI: 10.1007/s00441-007-0464-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Accepted: 07/04/2007] [Indexed: 10/22/2022]
Abstract
Prosaposin is the precursor of four sphingolipid activator proteins (saposins A, B, C, and D) for lysosomal hydrolases and is abundant in the nervous system and muscle. In addition to its role as a precursor of saposins in lysosomes, intact prosaposin has neurotrophic effects in vivo or in vitro when supplied exogenously. We examined the distribution of prosaposin in the central and peripheral nervous systems and its intracellular distribution. Using a monospecific antisaposin D antibody that crossreacts with prosaposin but not with saposins A, B, or C, immunoblot experiments showed that both the central and peripheral nervous systems express unprocessed prosaposin and little saposin D. Using the antisaposin D antibodies, we demonstrated that prosaposin is abundant in almost all neurons of both the central and peripheral nervous systems, including autonomic nerves, as well as motor and sensory nerves. Immunoelectron microscopy using double staining with antisaposin D and anticathepsin D antibodies showed strong prosaposin immunoreactivity mainly in the lysosomal granules in the neurons in both the central and peripheral nervous systems. The expression of prosaposin mRNA, examined using in situ hybridization, was observed in these same neurons. Our results suggest that prosaposin is synthesized ubiquitously in neurons of both the central and peripheral nervous systems.
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Affiliation(s)
- Yoshiki Hosoda
- Department of Neuropsychiatry, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0212, Japan
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Sun Y, Witte DP, Zamzow M, Ran H, Quinn B, Matsuda J, Grabowski GA. Combined saposin C and D deficiencies in mice lead to a neuronopathic phenotype, glucosylceramide and α-hydroxy ceramide accumulation, and altered prosaposin trafficking. Hum Mol Genet 2007; 16:957-71. [PMID: 17353235 DOI: 10.1093/hmg/ddm040] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Saposins (A, B, C and D) are approximately 80 amino acid stimulators of glycosphingolipid (GSL) hydrolases that derive from a single precursor, prosaposin. In both humans and mice, prosaposin/saposin deficiencies lead to severe neurological deficits. The CD-/- mice with saposin C and D combined deficiencies were produced by introducing genomic point mutations into a critical cysteine in each of these saposins. These mice develop a severe neurological phenotype with ataxia, kyphotic posturing and hind limb paralysis. Relative to prosaposin null mice ( approximately 30 days), CD-/- mice had an extended life span ( approximately 56 days). Loss of Purkinje cells was evident after 6 weeks, and storage bodies were present in neurons of the spinal cord, brain and dorsal root ganglion. Electron microscopy showed well-myelinated fibers and axonal inclusions in the brain and sciatic nerve. Marked accumulations of glucosylceramides and alpha-hydroxy ceramides were present in brain and kidney. Minor storage of lactosylceramide (LacCer) was observed when compared with tissues from the prosaposin null mice, suggesting a compensation in LacCer degradation by saposin B for the saposin C deficiency. Skin fibroblasts and tissues from CD-/- mice showed an increase of intracellular prosaposin, impaired prosaposin secretion, deficiencies of saposins C and D and decreases in saposins A and B. In addition, the deficiency of saposin C in CD-/- mice resulted in cellular decreases of acid beta-glucosidase activity and protein. This CD null mouse model provides a tool to explore the in vivo functional interactions of saposins in GSL metabolism and lysosomal storage diseases, and prosaposin's physiological effects.
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Affiliation(s)
- Ying Sun
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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Terashita T, Saito S, Miyawaki K, Hyodo M, Kobayashi N, Shimokawa T, Saito K, Matsuda S, Gyo K. Localization of prosaposin in rat cochlea. Neurosci Res 2006; 57:372-8. [PMID: 17156877 DOI: 10.1016/j.neures.2006.11.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 10/20/2006] [Accepted: 11/07/2006] [Indexed: 01/23/2023]
Abstract
Prosaposin, the precursor of the sphingolipid hydrolase activator proteins called saposins A, B, C, and D, is abundant in the nervous system and muscles. Besides its role as the precursor of saposins, prosaposin is reported to function as a neurotrophic factor, initiating neural differentiation and preventing neuronal cell death in vivo and in vitro. In this study, we examined the localization and synthesis of prosaposin in the rat cochlea. Intense prosaposin immunoreactivity was observed in the organ of Corti, stria vascularis, and spiral ganglion. In an immuno-electron microscopic study, prosaposin immunoreactivity was found mainly in lysosomal granules of the cells in these regions. In the lysosome, prosaposin does not always colocalize with cathepsin D, but was localized mainly in the dark area of the lysosome. Prosaposin mRNA was observed in these same regions. Our results suggest that prosaposin plays a role in homeostasis in the peripheral auditory system.
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Affiliation(s)
- Takehiro Terashita
- Department of Basic Medical Research and Education, Ehime University School of Medicine, Shitsukawa, Toon, Ehime, Japan.
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Sun Y, Quinn B, Xu YH, Leonova T, Witte DP, Grabowski GA. Conditional expression of human acid β-glucosidase improves the visceral phenotype in a Gaucher disease mouse model. J Lipid Res 2006; 47:2161-70. [PMID: 16861620 DOI: 10.1194/jlr.m600239-jlr200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The reversibility and regression of histological and biochemical findings in a mouse model of Gaucher disease (4L/PS-NA) was evaluated using a liver-enriched activator protein promoter control of a tetracycline-controlled transcriptional activation-responsive human acid beta-glucosidase (hGCase) transgenic system. 4L/PS-NA has the acid beta-glucosidase (GCase) V394L/V394L (4L) point mutation combined with hypomorphic ( approximately 6% wild-type) expression of the mouse prosaposin transgene (PS-NA). The hGCase/4L/PS-NA had exclusive liver expression of hGCase controlled by doxycycline (DOX). In the absence of DOX, hGCase was secreted from liver at levels of approximately 120 microg/ml serum with only approximately 8% of full activity, following exposure to pH 7.4 in serum. The hGCase activity and protein were detected in cells of the liver (massive), lung, and spleen, but not the brain. The visceral tissue storage cells and glucosylceramide (GC) accumulation in hGCase/4L/PS-NA were decreased from that in 4L/PS-NA mice. Turning off hGCase expression with dietary DOX led to reaccumulation of storage cells and of GC in liver, lung, and spleen, and macrophage activation in those tissues. This study demonstrates that conditionally expressed hGCase supplemented the existing mutant mouse GCase to control visceral substrate accumulation in vivo.
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Affiliation(s)
- Ying Sun
- Division of Human Genetics, Children's Hospital Research Foundation and University of Cincinnati College of Medicine, Department of Pediatrics, Cincinnati, OH 45229-3039, USA
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Sawkar AR, Schmitz M, Zimmer KP, Reczek D, Edmunds T, Balch WE, Kelly JW. Chemical chaperones and permissive temperatures alter localization of Gaucher disease associated glucocerebrosidase variants. ACS Chem Biol 2006; 1:235-51. [PMID: 17163678 DOI: 10.1021/cb600187q] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Point mutations in the lysosomal hydrolase, glucocerebrosidase (GC), can cause Gaucher disease, a common lysosomal storage disease. Several clinically important GC mutations impede folding in the endoplasmic reticulum (ER) and target these enzymes for ER-associated degradation (ERAD). The removal of these misfolded proteins decreases the lysosomal concentration of GC, which results in glucosylceramide accumulation. The most common GC variant, N370S, and other clinically relevant variants, G202R and L444P, exhibit different cellular localization patterns in patient-derived fibroblasts. We show that these distributions can be altered by manipulation of the ER folding environment, either by chemical chaperones or by temperature shifts. N370S, L444P, and G202R GC are destabilized in the neutral pH environment of the ER, rendering them prone to ERAD. Fibroblasts harboring the G202R and L444P GC mutations grown at 30 degrees C localize the mutant proteins to the lysosome, and this increases total GC activity. Both of these temperature-sensitive mutants appear to be stable at 37 degrees C once they are trafficked to the low pH environment of the lysosome. Chemical chaperones correct the ER instability and significant ER retention of G202R GC. N370S is also destabilized under ER simulating conditions, a deficiency that is corrected by chemical chaperone binding. These data clearly show manipulating the ER environment with chemical chaperones increases the lysosomal concentration of partially active GC variants and suggest that small molecules could be used to treat Gaucher disease.
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Affiliation(s)
- Anu R Sawkar
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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26
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Sun Y, Quinn B, Witte DP, Grabowski GA. Gaucher disease mouse models: point mutations at the acid beta-glucosidase locus combined with low-level prosaposin expression lead to disease variants. J Lipid Res 2005; 46:2102-13. [PMID: 16061944 DOI: 10.1194/jlr.m500202-jlr200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gaucher disease is a common lysosomal storage disease caused by a defect of acid beta-glucosidase (GCase). The optimal in vitro hydrolase activity of GCase requires saposin C, an activator protein that derives from a precursor, prosaposin. To develop additional models of Gaucher disease and to test in vivo effects of saposin deficiencies, mice expressing low levels (4--45% of wild type) of prosaposin and saposins (PS-NA) were backcrossed into mice with specific point mutations (V394L/V394L or D409H/D409H) of GCase. The resultant mice were designated 4L/PS-NA and 9H/PS-NA, respectively. In contrast to PS-NA mice, the 4L/PS-NA and 9H/PS-NA mice displayed large numbers of engorged macrophages and nearly exclusive glucosylceramide (GC) accumulation in the liver, lung, spleen, thymus, and brain. Electron microscopy of the storage cells showed the characteristic tubular storage material of Gaucher cells. Compared with V394L/V394L mice, 4L/PS-NA mice that expressed 4--6% of wild-type prosaposin levels had approximately 25--75% decreases in GCase activity and protein in liver, spleen, and fibroblasts. These results imply that reduced saposin levels increased the instability of V394L or D409H GCases and that these additional decreases led to large accumulations of GC in all tissues. These models mimic a more severe Gaucher disease phenotype and could be useful for therapeutic intervention studies.
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Affiliation(s)
- Ying Sun
- Division and Program in Human Genetics, Children's Hospital Research Foundation, Cincinnati, OH 45229-3039, USA
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Gopalakrishnan M, Grosch HW, Locatelli-Hoops S, Werth N, Smolenová E, Nettersheim M, Sandhoff K, Hasilik A. Purified recombinant human prosaposin forms oligomers that bind procathepsin D and affect its autoactivation. Biochem J 2005; 383:507-15. [PMID: 15255780 PMCID: PMC1133744 DOI: 10.1042/bj20040175] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Before delivery to endosomes, portions of proCD (procathepsin D) and proSAP (prosaposin) are assembled into complexes. We demonstrate that such complexes are also present in secretions of cultured cells. To study the formation and properties of the complexes, we purified proCD and proSAP from culture media of Spodoptera frugiperda cells that were infected with baculoviruses bearing the respective cDNAs. The biological activity of proCD was demonstrated by its pH-dependent autoactivation to pseudocathepsin D and that of proSAP was demonstrated by feeding to saposin-deficient cultured cells that corrected the storage of radioactive glycolipids. In gel filtration, proSAP behaved as an oligomer and proCD as a monomer. ProSAP altered the elution of proCD such that the latter was shifted into proSAP-containing fractions. ProSAP did not change the elution of mature cathepsin D. Using surface plasmon resonance and an immobilized biotinylated proCD, binding of proSAP was demonstrated under neutral and weakly acidic conditions. At pH 6.8, specific binding appeared to involve more than one binding site on a proSAP oligomer. The dissociation of the first site was characterized by a K(D1) of 5.8+/-2.9x10(-8) M(-1) (calculated for the monomer). ProSAP stimulated the autoactivation of proCD and also the activity of pseudocathepsin D. Concomitant with the activation, proSAP behaved as a substrate yielding tri- and disaposins and smaller fragments. Our results demonstrate that proSAP forms oligomers that are capable of binding proCD spontaneously and independent of the mammalian type N-glycosylation but not capable of binding mature cathepsin D. In addition to binding proSAP, proCD behaves as an autoactivable and processing enzyme and its binding partner as an activator and substrate.
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Affiliation(s)
| | - Hans-Wilhelm Grosch
- *Institute of Physiological Chemistry, Philipps-University Marburg, Karl-von-Frisch-Strasse 1, 35033 Marburg, Germany
| | - Silvia Locatelli-Hoops
- †The Kekulé Institute for Organic Chemistry and Biochemistry, University of Bonn, 53121 Bonn, Germany
| | - Norbert Werth
- †The Kekulé Institute for Organic Chemistry and Biochemistry, University of Bonn, 53121 Bonn, Germany
| | - Eva Smolenová
- *Institute of Physiological Chemistry, Philipps-University Marburg, Karl-von-Frisch-Strasse 1, 35033 Marburg, Germany
| | - Michael Nettersheim
- †The Kekulé Institute for Organic Chemistry and Biochemistry, University of Bonn, 53121 Bonn, Germany
| | - Konrad Sandhoff
- †The Kekulé Institute for Organic Chemistry and Biochemistry, University of Bonn, 53121 Bonn, Germany
| | - Andrej Hasilik
- *Institute of Physiological Chemistry, Philipps-University Marburg, Karl-von-Frisch-Strasse 1, 35033 Marburg, Germany
- To whom correspondence should be addressed (email )
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Diaz-Font A, Cormand B, Santamaria R, Vilageliu L, Grinberg D, Chabás A. A mutation within the saposin D domain in a Gaucher disease patient with normal glucocerebrosidase activity. Hum Genet 2005; 117:275-7. [PMID: 15856305 DOI: 10.1007/s00439-005-1288-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Accepted: 01/25/2005] [Indexed: 11/29/2022]
Abstract
Only two Gaucher disease (GD) patients bearing mutations in the prosaposin gene (PSAP), and not in the glucocerebrosidase gene (GBA), have been reported. In both cases, one mutant allele remained unidentified. We report here the identification of the second mutation in one of these patients, being the first complete genotype described so far in a SAP-C-deficient GD patient. This mutation, p.Q430X, is the first one reported in the saposin D domain and probably produces a null allele by nonsense mediated mRNA decay.
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Affiliation(s)
- Anna Diaz-Font
- Departament de Genètica, Facultat de Biología, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain
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Unuma K, Chen J, Saito S, Kobayashi N, Sato K, Saito K, Wakisaka H, Mominoki K, Sano A, Matsuda S. Changes in expression of prosaposin in the rat facial nerve nucleus after facial nerve transection. Neurosci Res 2005; 52:220-7. [PMID: 15927723 DOI: 10.1016/j.neures.2005.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 03/05/2005] [Accepted: 03/18/2005] [Indexed: 11/30/2022]
Abstract
Prosaposin is the precursor of saposins A, B, C and D, which are activators of sphingolipid hydrolases. In addition, unprocessed prosaposin functions as a neurotrophic factor in the central and peripheral nervous systems by acting to prevent neuronal apoptosis, to elongate neurites and to facilitate myelination. In this study, the expression pattern of prosaposin in the facial nerve nucleus after facial nerve transection was examined by immunohistochemistry and in situ hybridization. Prosaposin immunoreactivity in the neurons on the operated side facial nerve nucleus showed a biphasic pattern: it was significantly increased on day 3 after transection, decreased dramatically on day 7, started to increase gradually on day 14 and reached another peak on day 21 after transection. Significant increases in the levels of prosaposin mRNA were identified in the neurons on the operated side, suggesting that prosaposin was synthesized vigorously by the neurons themselves in the case of facial nerve transection. The diverse changes in prosaposin immunoreactivity during the process of facial nerve regeneration may reflect the diverse neurotrophic activities of prosaposin in facial motoneurons.
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Affiliation(s)
- Kana Unuma
- Division of Anatomy and Embryology, Department of Integrated Basic Medical Science, Ehime University School of Medicine, Shitsukawa, Toon-shi, Ehime 791-0295, Japan
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30
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You HX, Qi X, Grabowski GA, Yu L. Phospholipid membrane interactions of saposin C: in situ atomic force microscopic study. Biophys J 2003; 84:2043-57. [PMID: 12609906 PMCID: PMC1302773 DOI: 10.1016/s0006-3495(03)75012-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2002] [Accepted: 10/28/2002] [Indexed: 10/21/2022] Open
Abstract
Saposin C (Sap C) is a small glycoprotein required for hydrolysis of glucosylceramidase in lysosomes. The full activity of glucosylceramidase requires the presence of both Sap C and acidic phospholipids. Interaction between Sap C and acidic phospholipid-containing membranes, a crucial step for enzyme activation, is not fully understood. In this study, the dynamic process of Sap C interaction with acidic phospholipid-containing membranes was investigated in aqueous buffer using atomic force microscopy. Sap C induced two types of membrane restructuring: formation of patch-like structural domains and the occurrence of membrane destabilization. The former caused thickness increase whereas the latter caused thickness reduction in the gel-phase membrane bilayer, possibly as a result of lipid loss or an interdigitating process. Patch-like domain formation was independent of acidic phospholipids, whereas membrane destabilization is dependent on the presence and concentration of acidic phospholipids. Sap C effects on membrane restructuring were further studied using synthetic peptides. Synthetic peptides corresponding to the amphipathic alpha-helical domains 1 (designated "H1 peptide") and 2 (H2 peptide) of Sap C were used. Our results indicated that H2 contributed to domain formation but not to membrane destabilization, whereas H1 induced neither type of membrane restructuring. However, H1 was able to mimic Sap C's destabilization effect in conjunction with H2, but only when H1 was present first and H2 was added afterwards. This study provides an approach to investigate the structure-function aspects of Sap C interaction with phospholipid membranes, with insights into the mechanism(s) of Sap C-membrane interaction.
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Affiliation(s)
- Hong Xing You
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Ohio 45267-0521, USA.
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31
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You HX, Yu L, Qi X. Phospholipid membrane restructuring induced by saposin C: a topographic study using atomic force microscopy. FEBS Lett 2001; 503:97-102. [PMID: 11513862 DOI: 10.1016/s0014-5793(01)02700-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The enzymatic activity of glucosylceramidase depends on the presence of saposin C (Sap C) and acidic phospholipid-containing membranes. In order to delineate the mechanism underlying Sap C stimulation of the enzyme activity, it is important to understand how Sap C interacts with phospholipid membranes. We studied the dynamic process of Sap C interaction with planar phospholipid membranes, in real time, using atomic force microscopy (AFM). The phospholipid membrane underwent restructuring upon addition of Sap C. The topographic characteristics of the membrane restructuring include the appearance of patch-like new features, initially emerged at the edge of phospholipid membranes and extended laterally with time. Changes in the image contrast of the phospholipid membrane observed after the Sap C addition indicate that a new phase of lipid-protein structure has formed during membrane restructuring. The process of membrane restructuring is dynamic, commencing shortly after Sap C addition, and continuing throughout the duration of AFM imaging (about 30 min, sometimes over 1 h). This study demonstrated the potential of AFM real-time imaging in studying protein-membrane interactions.
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Affiliation(s)
- H X You
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, OH 45267-0521, USA.
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