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Sharma P, Zhang X, Ly K, Kim JH, Wan Q, Kim J, Lou M, Kain L, Teyton L, Winau F. Hyperglycosylation of prosaposin in tumor dendritic cells drives immune escape. Science 2024; 383:190-200. [PMID: 38207022 DOI: 10.1126/science.adg1955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 11/27/2023] [Indexed: 01/13/2024]
Abstract
Tumors develop strategies to evade immunity by suppressing antigen presentation. In this work, we show that prosaposin (pSAP) drives CD8 T cell-mediated tumor immunity and that its hyperglycosylation in tumor dendritic cells (DCs) leads to cancer immune escape. We found that lysosomal pSAP and its single-saposin cognates mediated disintegration of tumor cell-derived apoptotic bodies to facilitate presentation of membrane-associated antigen and T cell activation. In the tumor microenvironment, transforming growth factor-β (TGF-β) induced hyperglycosylation of pSAP and its subsequent secretion, which ultimately caused depletion of lysosomal saposins. pSAP hyperglycosylation was also observed in tumor-associated DCs from melanoma patients, and reconstitution with pSAP rescued activation of tumor-infiltrating T cells. Targeting DCs with recombinant pSAP triggered tumor protection and enhanced immune checkpoint therapy. Our studies demonstrate a critical function of pSAP in tumor immunity and may support its role in immunotherapy.
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Affiliation(s)
- Pankaj Sharma
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Xiaolong Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Kevin Ly
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Ji Hyung Kim
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Qi Wan
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Jessica Kim
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Mumeng Lou
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Lisa Kain
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Luc Teyton
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Florian Winau
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
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2
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Nutter CA, Kidd BM, Carter HA, Hamel JI, Mackie PM, Kumbkarni N, Davenport ML, Tuyn DM, Gopinath A, Creigh PD, Sznajder ŁJ, Wang ET, Ranum LPW, Khoshbouei H, Day JW, Sampson JB, Prokop S, Swanson MS. Choroid plexus mis-splicing and altered cerebrospinal fluid composition in myotonic dystrophy type 1. Brain 2023; 146:4217-4232. [PMID: 37143315 PMCID: PMC10545633 DOI: 10.1093/brain/awad148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/08/2023] [Accepted: 04/18/2023] [Indexed: 05/06/2023] Open
Abstract
Myotonic dystrophy type 1 is a dominantly inherited multisystemic disease caused by CTG tandem repeat expansions in the DMPK 3' untranslated region. These expanded repeats are transcribed and produce toxic CUG RNAs that sequester and inhibit activities of the MBNL family of developmental RNA processing factors. Although myotonic dystrophy is classified as a muscular dystrophy, the brain is also severely affected by an unusual cohort of symptoms, including hypersomnia, executive dysfunction, as well as early onsets of tau/MAPT pathology and cerebral atrophy. To address the molecular and cellular events that lead to these pathological outcomes, we recently generated a mouse Dmpk CTG expansion knock-in model and identified choroid plexus epithelial cells as particularly affected by the expression of toxic CUG expansion RNAs. To determine if toxic CUG RNAs perturb choroid plexus functions, alternative splicing analysis was performed on lateral and hindbrain choroid plexi from Dmpk CTG knock-in mice. Choroid plexus transcriptome-wide changes were evaluated in Mbnl2 knockout mice, a developmental-onset model of myotonic dystrophy brain dysfunction. To determine if transcriptome changes also occurred in the human disease, we obtained post-mortem choroid plexus for RNA-seq from neurologically unaffected (two females, three males; ages 50-70 years) and myotonic dystrophy type 1 (one female, three males; ages 50-70 years) donors. To test that choroid plexus transcriptome alterations resulted in altered CSF composition, we obtained CSF via lumbar puncture from patients with myotonic dystrophy type 1 (five females, five males; ages 35-55 years) and non-myotonic dystrophy patients (three females, four males; ages 26-51 years), and western blot and osmolarity analyses were used to test CSF alterations predicted by choroid plexus transcriptome analysis. We determined that CUG RNA induced toxicity was more robust in the lateral choroid plexus of Dmpk CTG knock-in mice due to comparatively higher Dmpk and lower Mbnl RNA levels. Impaired transitions to adult splicing patterns during choroid plexus development were identified in Mbnl2 knockout mice, including mis-splicing previously found in Dmpk CTG knock-in mice. Whole transcriptome analysis of myotonic dystrophy type 1 choroid plexus revealed disease-associated RNA expression and mis-splicing events. Based on these RNA changes, predicted alterations in ion homeostasis, secretory output and CSF composition were confirmed by analysis of myotonic dystrophy type 1 CSF. Our results implicate choroid plexus spliceopathy and concomitant alterations in CSF homeostasis as an unappreciated contributor to myotonic dystrophy type 1 CNS pathogenesis.
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Affiliation(s)
- Curtis A Nutter
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Benjamin M Kidd
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Helmut A Carter
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Johanna I Hamel
- Department of Neurology, University of Rochester, Rochester, NY 14642, USA
| | - Philip M Mackie
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Nayha Kumbkarni
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Mackenzie L Davenport
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Dana M Tuyn
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Adithya Gopinath
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Peter D Creigh
- Department of Neurology, University of Rochester, Rochester, NY 14642, USA
| | - Łukasz J Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Laura P W Ranum
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, McKnight Brain Institute and the Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Habibeh Khoshbouei
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - John W Day
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94304, USA
| | - Jacinda B Sampson
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94304, USA
| | - Stefan Prokop
- Department of Pathology, Immunology, and Laboratory Medicine, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute and the Fixel Institute for Neurological Diseases, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
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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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Sharma P, Zhang X, Ly K, Kim JH, Wan Q, Kim J, Lou M, Kain L, Teyton L, Winau F. Hyperglycosylation of prosaposin in tumor DCs promotes immune escape in cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.545005. [PMID: 37398287 PMCID: PMC10312684 DOI: 10.1101/2023.06.14.545005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Tumors develop strategies to evade immunity by suppressing antigen presentation. Here, we show that prosaposin drives CD8 T cell-mediated tumor immunity and that its hyperglycosylation in tumor DCs leads to cancer immune escape. We found that lysosomal prosaposin and its single saposin cognates mediated disintegration of tumor cell-derived apoptotic bodies to facilitate presentation of membrane-associated antigen and T cell activation. In the tumor microenvironment, TGF-β induced hyperglycosylation of prosaposin and its subsequent secretion, which ultimately caused depletion of lysosomal saposins. In melanoma patients, we found similar prosaposin hyperglycosylation in tumor-associated DCs, and reconstitution with prosaposin rescued activation of tumor-infiltrating T cells. Targeting tumor DCs with recombinant prosaposin triggered cancer protection and enhanced immune checkpoint therapy. Our studies demonstrate a critical function of prosaposin in tumor immunity and escape and introduce a novel principle of prosaposin-based cancer immunotherapy. One Sentence Summary Prosaposin facilitates antigen cross-presentation and tumor immunity and its hyperglycosylation leads to immune evasion.
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Role of Prosaposin and Extracellular Sulfatase Sulf-1 Detection in Pleural Effusions as Diagnostic Biomarkers of Malignant Mesothelioma. Biomedicines 2022; 10:biomedicines10112803. [PMID: 36359323 PMCID: PMC9687327 DOI: 10.3390/biomedicines10112803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/25/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022] Open
Abstract
Malignant pleural mesothelioma is an aggressive malignancy with poor prognosis. Unilateral pleural effusion is frequently the initial clinical sign requiring therapeutic thoracentesis, which also offers a diagnostic opportunity. Detection of soluble biomarkers can support diagnosis, but few show good diagnostic accuracy. Here, we studied the expression levels and discriminative power of two putative biomarkers, prosaposin and extracellular sulfatase SULF-1, identified by proteomic and transcriptomic analysis, respectively. Pleural effusions from a total of 44 patients (23 with mesothelioma, 8 with lung cancer, and 13 with non-malignant disease) were analyzed for prosaposin and SULF-1 by enzyme-linked immunosorbent assay. Pleural effusions from mesothelioma patients had significantly higher levels of prosaposin and SULF-1 than those from non-malignant disease patients. Receiver-operating characteristic (ROC) analysis showed that both biomarkers have good discriminating power as pointed out by an AUC value of 0.853 (p = 0.0005) and 0.898 (p < 0.0001) for prosaposin and SULF-1, respectively. Combining data ensued a model predicting improvement of the diagnostic performance (AUC = 0.916, p < 0.0001). In contrast, prosaposin couldn’t discriminate mesothelioma patients from lung cancer patients while ROC analysis of SULF-1 data produced an AUC value of 0.821 (p = 0.0077) but with low sensitivity. In conclusion, prosaposin and SULF-1 levels determined in pleural effusion may be promising biomarkers for differential diagnosis between mesothelioma and non-malignant pleural disease. Instead, more patients need to be enrolled before granting the possible usefulness of these soluble proteins in differentiating mesothelioma pleural effusions from those linked to lung cancer.
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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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Castration causes an increase in lysosomal size and upregulation of cathepsin D expression in principal cells along with increased secretion of procathepsin D and prosaposin oligomers in adult rat epididymis. PLoS One 2021; 16:e0250454. [PMID: 33914781 PMCID: PMC8084160 DOI: 10.1371/journal.pone.0250454] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/06/2021] [Indexed: 11/19/2022] Open
Abstract
In the epididymis, lysosomal proteins of the epithelial cells are normally targeted from the Golgi apparatus to lysosomes for degradation, although their secretion into the epididymal lumen has been documented and associated with sperm maturation. In this study, cathepsin D (CatD) and prosaposin (PSAP) were examined in adult epididymis of control, and 2-day castrated rats without (Ct) and with testosterone replacement (Ct+T) to evaluate their expression and regulation within epididymal epithelial cells. By light microscope-immunocytochemistry, a quantitative increase in size of lysosomes in principal cells of Ct animals was noted from the distal initial segment to the proximal cauda. Androgen replacement did not restore the size of lysosomes to control levels. Western blot analysis revealed a significant increase in CatD expression in the epididymis of Ct animals, which suggested an upregulation of its expression in principal cells; androgens restored levels of CatD to that of controls. In contrast, PSAP expression in Ct animals was not altered from controls. Additionally, an increase in procathepsin D levels was noted from samples of the epididymal fluid of Ct compared to control animals, accompanied by an increased complex formation with PSAP. Moreover, an increased oligomerization of prosaposin was observed in the epididymal lumen of Ct rats, with changes reverted to controls in Ct+T animals. Taken together these data suggest castration causes an increased uptake of substrates that are acted upon by CatD in lysosomes of principal cells and in the lumen by procathepsin D. These substrates may be derived from apoptotic cells noted in the lumen of proximal regions and possibly by degenerating sperm in distal regions of the epididymis of Ct animals. Exploring the mechanisms by which lysosomal enzymes are synthesized and secreted by the epididymis may help resolve some of the issues originating from epididymal dysfunctions with relevance to sperm maturation.
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Shimokawa T, Nabeka H, Khan SI, Yamamiya K, Doihara T, Kobayashi N, Wakisaka H, Matsuda S. Prosaposin in the rat oviductal epithelial cells. Cell Tissue Res 2020; 383:1191-1202. [PMID: 33242172 DOI: 10.1007/s00441-020-03339-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 11/05/2020] [Indexed: 10/22/2022]
Abstract
Prosaposin (PSAP) has two forms: a precursor and a secreted form. The secreted form has neurotrophic, myelinotrophic, and myotrophic properties. The precursor form is a precursor protein of saposins A-D. Although the distribution of PSAP in male reproductive organs is well known, its distribution in female reproductive organs, especially in the oviduct, is unclear. Immunoblots and immunohistochemistry of oviducts showed that oviductal tissues contain PSAP proteins, and a significant increase in PSAP was observed in the estrus-metestrus phase compared to the diestrus-proestrus phase in the ampulla. To identify PSAP trafficking in cells, double-immunostaining was performed with antibodies against PSAP in combination with sortilin, mannose 6 phosphate receptor (M6PR), or low-density lipoprotein receptor-related protein 1 (LRP1). PSAP and sortilin double-positive reactions were observed near the nuclei, as well as in the apical portion of microvillous epithelial cells, whereas these reactions were only observed near the nuclei of ciliated epithelial cells. PSAP and M6PR double-positive reactions were observed near the nuclei of microvillous and ciliated epithelial cells. PSAP and M6PR double-positive reactions were also observed in the apical portion of microvillous epithelial cells. PSAP and LRP1 double-positive reactions were observed in the plasma membrane and apical portion of both microvillous and ciliated epithelial cells. Immunoelectron staining revealed PSAP immunoreactive small vesicles with exocytotic features at the apical portion of microvillous epithelial cells. These findings suggest that PSAP is present in the oviductal epithelium and has a pivotal role during pregnancy in providing an optimal environment for gametes and/or sperm in the ampulla.
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Affiliation(s)
- Tetsuya Shimokawa
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan.
| | - Hiroaki Nabeka
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan
| | - Sakirul Islam Khan
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan
| | - Kimiko Yamamiya
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan
| | - Takuya Doihara
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan
| | - Naoto Kobayashi
- Medical Education Center, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, Japan
| | - Hiroyuki Wakisaka
- Department of Liberal Arts, Ehime Prefectural University of Health Sciences, 543 Takaoda, Tobe, Ehime, 791-2101, Japan
| | - Seiji Matsuda
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan
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Oji Y, Hatano T, Ueno SI, Funayama M, Ishikawa KI, Okuzumi A, Noda S, Sato S, Satake W, Toda T, Li Y, Hino-Takai T, Kakuta S, Tsunemi T, Yoshino H, Nishioka K, Hattori T, Mizutani Y, Mutoh T, Yokochi F, Ichinose Y, Koh K, Shindo K, Takiyama Y, Hamaguchi T, Yamada M, Farrer MJ, Uchiyama Y, Akamatsu W, Wu YR, Matsuda J, Hattori N. Variants in saposin D domain of prosaposin gene linked to Parkinson's disease. Brain 2020; 143:1190-1205. [PMID: 32201884 DOI: 10.1093/brain/awaa064] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/30/2019] [Accepted: 01/20/2020] [Indexed: 01/08/2023] Open
Abstract
Recently, the genetic variability in lysosomal storage disorders has been implicated in the pathogenesis of Parkinson's disease. Here, we found that variants in prosaposin (PSAP), a rare causative gene of various types of lysosomal storage disorders, are linked to Parkinson's disease. Genetic mutation screening revealed three pathogenic mutations in the saposin D domain of PSAP from three families with autosomal dominant Parkinson's disease. Whole-exome sequencing revealed no other variants in previously identified Parkinson's disease-causing or lysosomal storage disorder-causing genes. A case-control association study found two variants in the intronic regions of the PSAP saposin D domain (rs4747203 and rs885828) in sporadic Parkinson's disease had significantly higher allele frequencies in a combined cohort of Japan and Taiwan. We found the abnormal accumulation of autophagic vacuoles, impaired autophagic flux, altered intracellular localization of prosaposin, and an aggregation of α-synuclein in patient-derived skin fibroblasts or induced pluripotent stem cell-derived dopaminergic neurons. In mice, a Psap saposin D mutation caused progressive motor decline and dopaminergic neurodegeneration. Our data provide novel genetic evidence for the involvement of the PSAP saposin D domain in Parkinson's disease.
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Affiliation(s)
- Yutaka Oji
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Taku Hatano
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shin-Ichi Ueno
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Manabu Funayama
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Kei-Ichi Ishikawa
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Center for Genomic and Regenerative Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Ayami Okuzumi
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Sachiko Noda
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shigeto Sato
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Wataru Satake
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tatsushi Toda
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yuanzhe Li
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tomoko Hino-Takai
- Department of Pathophysiology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Soichiro Kakuta
- Laboratory of Morphology and Image Analysis, Research Support Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Taiji Tsunemi
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Hiroyo Yoshino
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Kenya Nishioka
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tatsuya Hattori
- Department of Neurology, Hommachi Neurological Clinic, Nagoya, Japan
| | - Yasuaki Mizutani
- Department of Neurology, Fujita Health University School of Medicine, Aichi, Japan
| | - Tatsuro Mutoh
- Department of Neurology, Fujita Health University School of Medicine, Aichi, Japan
| | - Fusako Yokochi
- Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan
| | - Yuta Ichinose
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Kishin Koh
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Kazumasa Shindo
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Yoshihisa Takiyama
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Tsuyoshi Hamaguchi
- Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Masahito Yamada
- Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Matthew J Farrer
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada.,Department of Neurology, University of Florida, Gainesville, USA
| | - Yasuo Uchiyama
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Wado Akamatsu
- Center for Genomic and Regenerative Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yih-Ru Wu
- Department of Neurology, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Junko Matsuda
- Department of Pathophysiology and Metabolism, Kawasaki Medical School, Okayama, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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Paciotti S, Gatticchi L, Beccari T, Parnetti L. Lysosomal enzyme activities as possible CSF biomarkers of synucleinopathies. Clin Chim Acta 2019; 495:13-24. [PMID: 30922855 DOI: 10.1016/j.cca.2019.03.1627] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 03/19/2019] [Accepted: 03/23/2019] [Indexed: 01/28/2023]
Abstract
Mutations on the GBA gene, encoding for the lysosomal enzyme β-glucocerebrosidase (GCase), have been identified as the most common genetic risk factor involved in the development of Parkinson's disease (PD) and dementia with Lewy bodies (DLB), indicating a direct contribution of this enzyme to the pathogenesis of synucleinopathies. Decreased GCase activity has been observed repeatedly in brain tissues and biological fluids of both GBA mutation carrier and non-carrier PD and DLB patients, suggesting that lower GCase activity constitutes a typical feature of these disorders. Additional genetic, pathological and biochemical data on other lysosomal enzymes (e.g., Acid sphingomyelinase, Cathepsin D, α-galactosidase A and β-hexosaminidase) have further strengthened the evidence of a link between lysosomal dysfunction and synucleinopathies. A few studies have been performed for assessing the potential value of lysosomal enzyme activities in cerebrospinal fluid (CSF) as biomarkers for synucleinopathies. The reduction of GCase activity in the CSF of PD and DLB patients was validated in several of them, whereas the behaviour of other lysosomal enzyme activities was not consistently reliable among the studies. More in-depth investigations on larger cohorts, following stringent standard operating procedures should be committed to really understand the diagnostic utility of lysosomal enzymes as biomarkers for synucleinopathies. In this review, we reported the evidences of the association between the defective function of lysosomal proteins and the pathogenesis of synucleinopathies, and examined the role of lysosomal enzyme activities in CSF as reliable biomarkers for the diagnosis of PD and related neurodegenerative disorders.
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Affiliation(s)
- Silvia Paciotti
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia, Perugia, Italy; Laboratory of Clinical Neurochemistry, Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy.
| | - Leonardo Gatticchi
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Tommaso Beccari
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy.
| | - Lucilla Parnetti
- Laboratory of Clinical Neurochemistry, Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy.
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Parnetti L, Paciotti S, Eusebi P, Dardis A, Zampieri S, Chiasserini D, Tasegian A, Tambasco N, Bembi B, Calabresi P, Beccari T. Cerebrospinal fluid β-glucocerebrosidase activity is reduced in parkinson's disease patients. Mov Disord 2017; 32:1423-1431. [PMID: 28843015 DOI: 10.1002/mds.27136] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 06/20/2017] [Accepted: 06/26/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Reduced β-glucocerebrosidase activity was observed in postmortem brains of both GBA1 mutation carrier and noncarrier Parkinson's disease patients, suggesting that lower β-glucocerebrosidase activity is a key feature in the pathogenesis of PD. The objectives of this study were to confirm whether there is reduced β-glucocerebrosidase activity in the CSF of GBA1 mutation carrier and noncarrier PD patients and verify if other lysosomal enzymes show altered activity in the CSF. METHODS CSF β-glucocerebrosidase, cathepsin D, and β-hexosaminidase activities were measured in 79 PD and 61 healthy controls from the BioFIND cohort. The whole GBA1 gene was sequenced. RESULTS Enzyme activities were normalized according to CSF protein content (specific activity). β-glucocerebrosidase specific activity was significantly decreased in PD versus controls (-28%, P < 0.001). GBA1 mutations were found in 10 of 79 PD patients (12.7%) and 3 of 61 controls (4.9%). GBA1 mutation carrier PD patients showed significantly lower β-glucocerebrosidase specific activity versus noncarriers. β-glucocerebrosidase specific activity was also decreased in noncarrier PD patients versus controls (-25%, P < 0.001). Cathepsin D specific activity was lower in PD versus controls (-21%, P < 0.001). β-Hexosaminidase showed a similar trend. β-Glucocerebrosidase specific activity fairly discriminated PD from controls (area under the curve, 0.72; sensitivity, 0.67; specificity, 0.77). A combination of β-glucocerebrosidase, cathepsin D, and β-hexosaminidase improved diagnostic accuracy (area under the curve, 0.77; sensitivity, 0.71; specificity, 0.85). Lower β-glucocerebrosidase and β-hexosaminidase specific activities were associated with worse cognitive performance. CONCLUSIONS CSF β-glucocerebrosidase activity is reduced in PD patients independent of their GBA1 mutation carrier status. Cathepsin D and β-hexosaminidase were also decreased. The possible link between altered CSF lysosomal enzyme activities and cognitive decline deserves further investigation. © 2017 International Parkinson and Movement Disorder Society.
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Affiliation(s)
| | - Silvia Paciotti
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Paolo Eusebi
- Neurology Clinic, University of Perugia, Perugia, Italy
| | - Andrea Dardis
- Regional Coordinating Centre for Rare Diseases, University Hospital Santa Maria della Misericordia, Udine, Italy
| | - Stefania Zampieri
- Regional Coordinating Centre for Rare Diseases, University Hospital Santa Maria della Misericordia, Udine, Italy
| | | | - Anna Tasegian
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | | | - Bruno Bembi
- Regional Coordinating Centre for Rare Diseases, University Hospital Santa Maria della Misericordia, Udine, Italy
| | | | - Tommaso Beccari
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
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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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Kang L, Zhan X, Ye J, Han L, Qiu W, Gu X, Zhang H. A rare form of Gaucher disease resulting from saposin C deficiency. Blood Cells Mol Dis 2017; 68:60-65. [PMID: 28457694 DOI: 10.1016/j.bcmd.2017.04.001] [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] [Received: 02/14/2017] [Revised: 04/02/2017] [Accepted: 04/02/2017] [Indexed: 11/27/2022]
Abstract
Gaucher disease is mainly caused by the deficiency of lysosomal acid β-glucosidase. Gaucher disease caused by the deficiency of saposin C is rare. Here we report a patient mainly presenting with hepatosplenomegaly, thrombocytopenia and anemia. EEG examination revealed increased theta waves. Gaucher cells identified in his bone marrow and the highly elevated plasma chitotriosidase activity and glucosylsphingosine supported a diagnosis of Gaucher disease. However, the leukocyte β-glucosidase activity was in a normal range. Sanger sequencing revealed a novel maternal exonic mutation c.1133C>G (p.Pro378Arg) in exon 10 of the PSAP gene, which codes the Sap C domain of PSAP protein. To search for other underlying mutations in this patient, whole genome sequencing was applied and revealed a deletion involving exon 2 to 7 of PSAP gene. The deletion appears as a de novo event on paternal chromosome. We concluded that biallelic mutations of PSAP gene were the cause of this patient's Gaucher disease. Our finding expands the mutation spectrum of Gaucher disease with saposin C deficiency.
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Affiliation(s)
- Lulu Kang
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China
| | - Xia Zhan
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China
| | - Jun Ye
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China
| | - Lianshu Han
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China
| | - Wenjuan Qiu
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China
| | - Xuefan Gu
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China
| | - Huiwen Zhang
- Pediatric Endocrinology and Genetic, Xin Hua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiao Tong University School of Medicine, China.
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Meyer RC, Giddens MM, Coleman BM, Hall RA. The protective role of prosaposin and its receptors in the nervous system. Brain Res 2014; 1585:1-12. [PMID: 25130661 DOI: 10.1016/j.brainres.2014.08.022] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 07/18/2014] [Accepted: 08/10/2014] [Indexed: 12/12/2022]
Abstract
Prosaposin (also known as SGP-1) is an intriguing multifunctional protein that plays roles both intracellularly, as a regulator of lysosomal enzyme function, and extracellularly, as a secreted factor with neuroprotective and glioprotective effects. Following secretion, prosaposin can undergo endocytosis via an interaction with the low-density lipoprotein-related receptor 1 (LRP1). The ability of secreted prosaposin to promote protective effects in the nervous system is known to involve activation of G proteins, and the orphan G protein-coupled receptors GPR37 and GPR37L1 have recently been shown to mediate signaling induced by both prosaposin and a fragment of prosaposin known as prosaptide. In this review, we describe recent advances in our understanding of prosaposin, its receptors and their importance in the nervous system.
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Affiliation(s)
- Rebecca C Meyer
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Michelle M Giddens
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Brilee M Coleman
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Randy A Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, United States.
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Siebert M, Sidransky E, Westbroek W. Glucocerebrosidase is shaking up the synucleinopathies. ACTA ACUST UNITED AC 2014; 137:1304-22. [PMID: 24531622 DOI: 10.1093/brain/awu002] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The lysosomal enzyme glucocerebrosidase, encoded by the glucocerebrosidase gene, is involved in the breakdown of glucocerebroside into glucose and ceramide. Lysosomal build-up of the substrate glucocerebroside occurs in cells of the reticulo-endothelial system in patients with Gaucher disease, a rare lysosomal storage disorder caused by the recessively inherited deficiency of glucocerebrosidase. Gaucher disease has a broad clinical phenotypic spectrum, divided into non-neuronopathic and neuronopathic forms. Like many monogenic diseases, the correlation between clinical manifestations and molecular genotype is not straightforward. There is now a well-established clinical association between mutations in the glucocerebrosidase gene and the development of more prevalent multifactorial disorders including Parkinson's disease and other synucleinopathies. In this review we discuss recent studies advancing our understanding of the cellular relationship between glucocerebrosidase and α-synuclein, the potential impact of established and emerging therapeutics for Gaucher disease for the treatment of the synucleinopathies, and the role of lysosomal pathways in the pathogenesis of these neurodegenerative disorders.
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Affiliation(s)
- Marina Siebert
- 1 Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Building 35 Room 1A213, 35 Convent Drive, MSC 3708, Bethesda, MD 20892-3708, USA
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Schuchman EH, Simonaro CM. The genetics of sphingolipid hydrolases and sphingolipid storage diseases. Handb Exp Pharmacol 2013:3-32. [PMID: 23579447 DOI: 10.1007/978-3-7091-1368-4_1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The relationship of sphingolipids with human disease first arose from the study of sphingolipid storage diseases over 50 years ago. Most of these disorders are due to inherited deficiencies of specific sphingolipid hydrolases, although a small number also result from defects in sphingolipid transport or activator proteins. Due to the primary protein deficiencies sphingolipids and other macromolecules accumulate in cells and tissues of affected patients, leading to a diverse presentation of clinical abnormalities. Over 25 sphingolipid storage diseases have been described to date. Most of the genes have been isolated, disease-causing mutations have been identified, the recombinant proteins have been produced and characterized, and animal models exist for most of the human diseases. Since most sphingolipid hydrolases are enriched within the endosomal/lysosomal system, macromolecules first accumulate within these compartments. However, these abnormalities rapidly spread to other compartments and cause a wide range of cellular dysfunction. This review focuses on the genetics of sphingolipid storage diseases and related hydrolytic enzymes with an emphasis on the relationship between genetic mutations and human disease.
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Affiliation(s)
- Edward H Schuchman
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, NY 10029, USA.
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Tamargo RJ, Velayati A, Goldin E, Sidransky E. The role of saposin C in Gaucher disease. Mol Genet Metab 2012; 106:257-63. [PMID: 22652185 PMCID: PMC3534739 DOI: 10.1016/j.ymgme.2012.04.024] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 04/28/2012] [Accepted: 04/29/2012] [Indexed: 12/16/2022]
Abstract
Saposin C is one of four homologous proteins derived from sequential cleavage of the saposin precursor protein, prosaposin. It is an essential activator for glucocerebrosidase, the enzyme deficient in Gaucher disease. Gaucher disease is a rare autosomal recessive lysosomal storage disorder caused by mutations in the GBA gene that exhibits vast phenotypic heterogeneity, despite its designation as a "simple" Mendelian disorder. The observed phenotypic variability has led to a search for disease modifiers that can alter the Gaucher phenotype. The PSAP gene encoding saposin C is a prime candidate modifier for Gaucher disease. In humans, saposin C deficiency due to mutations in PSAP results in a Gaucher-like phenotype, despite normal in vitro glucocerebrosidase activity. Saposin C deficiency has also been shown to modify phenotype in one mouse model of Gaucher disease. The role of saposin C as an activator required for normal glucocerebrosidase function, and the consequences of saposin C deficiency are described, and are being explored as potential modifying factors in patients with Gaucher disease.
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Affiliation(s)
- Rafael J. Tamargo
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Arash Velayati
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ehud Goldin
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ellen Sidransky
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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