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Grabowski GA, Antommaria AHM, Kolodny EH, Mistry PK. Gaucher disease: Basic and translational science needs for more complete therapy and management. Mol Genet Metab 2021; 132:59-75. [PMID: 33419694 PMCID: PMC8809485 DOI: 10.1016/j.ymgme.2020.12.291] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/15/2020] [Accepted: 12/18/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Gregory A Grabowski
- Department of Pediatrics, University of Cincinnati College of Medicine, United States of America; Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, United States of America; Division of Human Genetics, Cincinnati Children's Research Foundation, Cincinnati, OH, United States of America.
| | - Armand H M Antommaria
- Department of Pediatrics, University of Cincinnati College of Medicine, United States of America; Lee Ault Carter Chair of Pediatric Ethics, Cincinnati Children's Research Foundation, Cincinnati, OH, United States of America.
| | - Edwin H Kolodny
- Department of Neurology, New York University Grossman School of Medicine, New York, NY, United States of America.
| | - Pramod K Mistry
- Departments of Medicine and Pediatrics, Yale School of Medicine, New Haven, CT, United States of America.
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2
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Koehler A, Karve A, Desai P, Arbiser J, Plas DR, Qi X, Read RD, Sasaki AT, Gawali VS, Toukam DK, Bhattacharya D, Kallay L, Pomeranz Krummel DA, Sengupta S. Reuse of Molecules for Glioblastoma Therapy. Pharmaceuticals (Basel) 2021; 14:99. [PMID: 33525329 PMCID: PMC7912673 DOI: 10.3390/ph14020099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Glioblastoma multiforme (GBM) is a highly malignant primary brain tumor. The current standard of care for GBM is the Stupp protocol which includes surgical resection, followed by radiotherapy concomitant with the DNA alkylator temozolomide; however, survival under this treatment regimen is an abysmal 12-18 months. New and emerging treatments include the application of a physical device, non-invasive 'tumor treating fields' (TTFs), including its concomitant use with standard of care; and varied vaccines and immunotherapeutics being trialed. Some of these approaches have extended life by a few months over standard of care, but in some cases are only available for a minority of GBM patients. Extensive activity is also underway to repurpose and reposition therapeutics for GBM, either alone or in combination with the standard of care. In this review, we present select molecules that target different pathways and are at various stages of clinical translation as case studies to illustrate the rationale for their repurposing-repositioning and potential clinical use.
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Affiliation(s)
- Abigail Koehler
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
| | - Aniruddha Karve
- Division of Pharmaceutical Sciences, University of Cincinnati James L. Winkle College of Pharmacy, Cincinnati, OH 45229, USA; (A.K.); (P.D.)
| | - Pankaj Desai
- Division of Pharmaceutical Sciences, University of Cincinnati James L. Winkle College of Pharmacy, Cincinnati, OH 45229, USA; (A.K.); (P.D.)
| | - Jack Arbiser
- Department of Dermatology, Emory School of Medicine, Atlanta, GA 30322, USA;
- Atlanta Veterans Administration Medical Center, Decatur, GA 30033, USA
| | - David R. Plas
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA;
| | - Xiaoyang Qi
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (X.Q.); (A.T.S.)
| | - Renee D. Read
- Department of Pharmacology and Chemical Biology, Emory School of Medicine, Atlanta, GA 30322, USA;
| | - Atsuo T. Sasaki
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (X.Q.); (A.T.S.)
| | - Vaibhavkumar S. Gawali
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
| | - Donatien K. Toukam
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
| | - Debanjan Bhattacharya
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
| | - Laura Kallay
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
| | - Daniel A. Pomeranz Krummel
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
| | - Soma Sengupta
- Department of Neurology and Rehabilitation Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; (A.K.); (V.S.G.); (D.K.T.); (D.B.); (L.K.); (D.A.P.K.)
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3
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Dupuis JH, Wang S, Song C, Yada RY. The role of disulfide bonds in a Solanum tuberosum saposin-like protein investigated using molecular dynamics. PLoS One 2020; 15:e0237884. [PMID: 32841243 PMCID: PMC7447066 DOI: 10.1371/journal.pone.0237884] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/04/2020] [Indexed: 01/31/2023] Open
Abstract
The Solanum tuberosum plant specific insert (StPSI) has a defensive role in potato plants, with the requirements of acidic pH and anionic lipids. The StPSI contains a set of three highly conserved disulfide bonds that bridge the protein’s helical domains. Removal of these bonds leads to enhanced membrane interactions. This work examined the effects of their sequential removal, both individually and in combination, using all-atom molecular dynamics to elucidate the role of disulfide linkages in maintaining overall protein tertiary structure. The tertiary structure was found to remain stable at both acidic (active) and neutral (inactive) pH despite the removal of disulfide linkages. The findings include how the dimer structure is stabilized and the impact on secondary structure on a residue-basis as a function of disulfide bond removal. The StPSI possesses an extensive network of inter-monomer hydrophobic interactions and intra-monomer hydrogen bonds, which is likely the key to the stability of the StPSI by stabilizing local secondary structure and the tertiary saposin-fold, leading to a robust association between monomers, regardless of the disulfide bond state. Removal of disulfide bonds did not significantly impact secondary structure, nor lead to quaternary structural changes. Instead, disulfide bond removal induces regions of amino acids with relatively higher or lower variation in secondary structure, relative to when all the disulfide bonds are intact. Although disulfide bonds are not required to preserve overall secondary structure, they may have an important role in maintaining a less plastic structure within plant cells in order to regulate membrane affinity or targeting.
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Affiliation(s)
- John H. Dupuis
- Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shenlin Wang
- College of Chemistry and Molecular Engineering and Beijing NMR Center, Peking University, Beijing, People's Republic of China
| | - Chen Song
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, People’s Republic of China
| | - Rickey Y. Yada
- Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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N'Guessan KF, Davis HW, Chu Z, Vallabhapurapu SD, Lewis CS, Franco RS, Olowokure O, Ahmad SA, Yeh JJ, Bogdanov VY, Qi X. Enhanced Efficacy of Combination of Gemcitabine and Phosphatidylserine-Targeted Nanovesicles against Pancreatic Cancer. Mol Ther 2020; 28:1876-1886. [PMID: 32516572 DOI: 10.1016/j.ymthe.2020.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 02/25/2020] [Accepted: 05/12/2020] [Indexed: 12/23/2022] Open
Abstract
Phosphatidylserine (PS) is often externalized in viable pancreatic cancer cells and is therapeutically targetable using PS-selective drugs. One of the first-line treatments for advanced pancreatic cancer disease, gemcitabine (GEM), provides only marginal benefit to patients. We therefore investigated the therapeutic benefits of combining GEM and the PS-targeting drug, saposin C-dioleoylphosphatidylserine (SapC-DOPS), for treating pancreatic ductal adenocarcinoma (PDAC). Using cell-cycle analyses and a cell surface PS-based sorting method in vitro, we observed an increase in surface PS as cells progress through the cell cycle from G1 to G2/M. We also observed that GEM treatment preferentially targets G1 phase cells that have low surface PS, resulting in an increased median surface PS level of PDAC cells. Inversely, SapC-DOPS preferentially targets high surface PS cells that are predominantly in the G2/M phase. Finally, combination therapy in subcutaneous and orthotopic PDAC tumors in vivo with SapC-DOPS and GEM or Abraxane (Abr)/GEM (one of the current standards of care) significantly inhibits tumor growth and increases survival compared with individual treatments. Our studies confirm a surface PS and cell cycle-based enhancement of cancer cytotoxicity following SapC-DOPS treatment in combination with GEM or Abr/GEM. Thus, PDAC patients treated with Abr/GEM may benefit from concurrent administration of SapC-DOPS.
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Affiliation(s)
- Kombo F N'Guessan
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; Department of Pathology and Laboratory Medicine, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, USA
| | - Harold W Davis
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Zhengtao Chu
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Subrahmanya D Vallabhapurapu
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Clayton S Lewis
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Robert S Franco
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Olugbenga Olowokure
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Syed A Ahmad
- Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jen Jen Yeh
- Lineberger Comprehensive Cancer Center, Departments of Surgery and Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Vladimir Y Bogdanov
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Xiaoyang Qi
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA; Department of Pathology and Laboratory Medicine, University of Cincinnati, College of Medicine, Cincinnati, OH 45267, USA; Division of Human Genetics, Department of Pediatrics, University of Cincinnati College of Medicine and Cincinnati Children's Hospital and Medical Center, Cincinnati, OH 45267, USA; Department of Biomedical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221, USA.
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5
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Sun Y, Liou B, Chu Z, Fannin V, Blackwood R, Peng Y, Grabowski GA, Davis HW, Qi X. Systemic enzyme delivery by blood-brain barrier-penetrating SapC-DOPS nanovesicles for treatment of neuronopathic Gaucher disease. EBioMedicine 2020; 55:102735. [PMID: 32279952 PMCID: PMC7251241 DOI: 10.1016/j.ebiom.2020.102735] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 12/30/2022] Open
Abstract
Background Enzyme replacement therapy (ERT) can positively affect the visceral manifestations of lysosomal storage diseases (LSDs). However, the exclusion of the intravenous ERT agents from the central nervous system (CNS) prevents direct therapeutic effects. Methods Using a neuronopathic Gaucher disease (nGD) mouse model, CNS-ERT was created using a systemic, non-invasive, and CNS-selective delivery system based on nanovesicles of saposin C (SapC) and dioleoylphosphatidylserine (DOPS) to deliver to CNS cells and tissues the corrective, functional acid β-glucosidase (GCase). Findings Compared to free GCase, human GCase formulated with SapC-DOPS nanovesicles (SapC-DOPS-GCase) was more stable in serum, taken up into cells, mostly by a mannose receptor-independent pathway, and resulted in higher activity in GCase-deficient cells. In contrast to free GCase, SapC-DOPS-GCase nanovesicles penetrated through the blood-brain barrier into the CNS. The CNS targeting was mediated by surface phosphatidylserine (PS) of blood vessel and brain cells. Increased GCase activity and reduced GCase substrate levels were found in the CNS of SapC-DOPS-GCase-treated nGD mice, which showed profound improvement in brain inflammation and neurological phenotypes. Interpretation This first-in-class CNS-ERT approach provides considerable promise of therapeutic benefits for neurodegenerative diseases. Funding This study was supported by the National Institutes of Health grants R21NS 095047 to XQ and YS, R01NS 086134 and UH2NS092981 in part to YS; Cincinnati Children's Hospital Medical Center Research Innovation/Pilot award to YS and XQ; Gardner Neuroscience Institute/Neurobiology Research Center Pilot award to XQ and YS, Hematology-Oncology Programmatic Support from University of Cincinnati and New Drug State Key Project grant 009ZX09102-205 to XQ.
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Affiliation(s)
- Ying Sun
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| | - Benjamin Liou
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Zhengtao Chu
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Venette Fannin
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Rachel Blackwood
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Yanyan Peng
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Gregory A Grabowski
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Harold W Davis
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Xiaoyang Qi
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA; Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati, College of Medicine, Cincinnati, OH, USA.
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6
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Zhou X, Paushter DH, Pagan MD, Kim D, Nunez Santos M, Lieberman RL, Overkleeft HS, Sun Y, Smolka MB, Hu F. Progranulin deficiency leads to reduced glucocerebrosidase activity. PLoS One 2019; 14:e0212382. [PMID: 31291241 PMCID: PMC6619604 DOI: 10.1371/journal.pone.0212382] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022] Open
Abstract
Mutation in the GRN gene, encoding the progranulin (PGRN) protein, shows a dose-dependent disease correlation, wherein haploinsufficiency results in frontotemporal lobar degeneration (FTLD) and complete loss results in neuronal ceroid lipofuscinosis (NCL). Although the exact function of PGRN is unknown, it has been increasingly implicated in lysosomal physiology. Here we report that PGRN interacts with the lysosomal enzyme, glucocerebrosidase (GCase), and is essential for proper GCase activity. GCase activity is significantly reduced in tissue lysates from PGRN-deficient mice. This is further evidence that reduced lysosomal hydrolase activity may be a pathological mechanism in cases of GRN-related FTLD and NCL.
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Affiliation(s)
- Xiaolai Zhou
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
| | - Daniel H. Paushter
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
| | - Mitchell D. Pagan
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
| | - Dongsung Kim
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
| | - Mariela Nunez Santos
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, NW, Atlanta, GA, United States of America
| | - Herman S. Overkleeft
- Leiden Institute of Chemistry, Leiden University, Gorlaeus Laboratories, RA Leiden, Netherlands
| | - Ying Sun
- Division of Human Genetics; Cincinnati Children's Hospital Medical Center and the Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Marcus B. Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, United States of America
- * E-mail:
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7
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Wen M, Jin Y, Zhang H, Sun X, Kuai Y, Tan W. Proteomic Analysis of Rat Cerebral Cortex in the Subacute to Long-Term Phases of Focal Cerebral Ischemia-Reperfusion Injury. J Proteome Res 2019; 18:3099-3118. [PMID: 31265301 DOI: 10.1021/acs.jproteome.9b00220] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Stroke is a leading cause of mortality and disability, and ischemic stroke accounts for more than 80% of the disease occurrence. Timely reperfusion is essential in the treatment of ischemic stroke, but it is known to cause ischemia-reperfusion (I/R) injury and the relevant studies have mostly focused on the acute phase. Here we reported on a global proteomic analysis to investigate the development of cerebral I/R injury in the subacute and long-term phases. A rat model was used, with 2 h-middle cerebral artery occlusion (MCAO) followed with 1, 7, and 14 days of reperfusion. The proteins of cerebral cortex were analyzed by SDS-PAGE, whole-gel slicing, and quantitative LC-MS/MS. Totally 5621 proteins were identified, among which 568, 755, and 492 proteins were detected to have significant dys-regulation in the model groups with 1, 7, and 14 days of reperfusion, respectively, when compared with the corresponding sham groups (n = 4, fold change ≥1.5 or ≤0.67 and p ≤ 0.05). Bioinformatic analysis on the functions and reperfusion time-dependent dys-regulation profiles of the proteins exhibited changes of structures and biological processes in cytoskeleton, synaptic plasticity, energy metabolism, inflammation, and lysosome from subacute to long-term phases of cerebral I/R injury. Disruption of cytoskeleton and synaptic structures, impairment of energy metabolism processes, and acute inflammation responses were the most significant features in the subacute phase. With the elongation of reperfusion time to the long-term phase, a tendency of recovery was detected on cytoskeleton, while inflammation pathways different from the subacute phase were activated. Also, lysosomal structures and functions might be restored. This is the first work reporting the proteome changes that occurred at different time points from the subacute to long-term phases of cerebral I/R injury and we expect it would provide useful information to improve the understanding of the mechanisms involved in the development of cerebral I/R injury and suggest candidates for treatment.
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Affiliation(s)
- Meiling Wen
- School of Biology and Biological Engineering , South China University of Technology , Guangzhou 510006 , P. R. China
| | - Ya Jin
- Institute of Biomedical and Pharmaceutical Sciences , Guangdong University of Technology , Guangzhou 510006 , P. R. China
| | - Hao Zhang
- Institute of Biomedical and Pharmaceutical Sciences , Guangdong University of Technology , Guangzhou 510006 , P. R. China
| | - Xiaoou Sun
- Institute of Biomedical and Pharmaceutical Sciences , Guangdong University of Technology , Guangzhou 510006 , P. R. China
| | - Yihe Kuai
- Institute of Biomedical and Pharmaceutical Sciences , Guangdong University of Technology , Guangzhou 510006 , P. R. China
| | - Wen Tan
- Institute of Biomedical and Pharmaceutical Sciences , Guangdong University of Technology , Guangzhou 510006 , P. R. China
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Mechanism of glucocerebrosidase activation and dysfunction in Gaucher disease unraveled by molecular dynamics and deep learning. Proc Natl Acad Sci U S A 2019; 116:5086-5095. [PMID: 30808805 DOI: 10.1073/pnas.1818411116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The lysosomal enzyme glucocerebrosidase-1 (GCase) catalyzes the cleavage of a major glycolipid glucosylceramide into glucose and ceramide. The absence of fully functional GCase leads to the accumulation of its lipid substrates in lysosomes, causing Gaucher disease, an autosomal recessive disorder that displays profound genotype-phenotype nonconcordance. More than 250 disease-causing mutations in GBA1, the gene encoding GCase, have been discovered, although only one of these, N370S, causes 70% of disease. Here, we have used a knowledge-based docking protocol that considers experimental data of protein-protein binding to generate a complex between GCase and its known facilitator protein saposin C (SAPC). Multiscale molecular-dynamics simulations were used to study lipid self-assembly, membrane insertion, and the dynamics of the interactions between different components of the complex. Deep learning was applied to propose a model that explains the mechanism of GCase activation, which requires SAPC. Notably, we find that conformational changes in the loops at the entrance of the substrate-binding site are stabilized by direct interactions with SAPC and that the loss of such interactions induced by N370S and another common mutation, L444P, result in destabilization of the complex and reduced GCase activation. Our findings provide an atomistic-level explanation for GCase activation and the precise mechanism through which N370S and L444P cause Gaucher disease.
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Davis HW, Vallabhapurapu SD, Chu Z, Vallabhapurapu SL, Franco RS, Mierzwa M, Kassing W, Barrett WL, Qi X. Enhanced phosphatidylserine-selective cancer therapy with irradiation and SapC-DOPS nanovesicles. Oncotarget 2019; 10:856-868. [PMID: 30783515 PMCID: PMC6368238 DOI: 10.18632/oncotarget.26615] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 12/29/2018] [Indexed: 02/06/2023] Open
Abstract
Normal living cells exhibit phosphatidylserine (PS) primarily within the intracellular leaflet of the plasma membrane. In contrast, viable cancer cells have high levels of PS on the external surface, and exhibit a broad range of surface PS, even within specific types of cancer. Agents that target surface PS have recently been developed to treat tumors and are expected to be more effective with higher surface PS levels. In this context, we examined whether surface PS is increased with irradiation. In vitro irradiation of cancer cell lines selected surviving cells that had higher surface PS in a dose- and time-dependent manner. This was more pronounced if surface PS was initially in the lower range for cancer cells. Radiation also increased the surface PS of tumor cells in subcutaneous xenografts in nude mice. We found an inverse relationship between steady state surface PS level of cancer cell lines and their sensitivity to radiation-induced cell death. In addition, serial irradiation, which selected surviving cells with higher surface PS, also increased resistance to radiation and to some chemotherapeutic drugs, suggesting a PS-dependent mechanism for development of resistance to therapy. On the other hand, fractionated radiation enhanced the effect of a novel anti-cancer, PS-targeting drug, SapC-DOPS, in some cancer cell lines. Our data suggest that we can group cancer cells into cells with low surface PS, which are sensitive to radiation, and high surface PS, which are sensitive to SapC-DOPS. Combination of these interventions may provide a potential new combination therapy.
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Affiliation(s)
- Harold W Davis
- Division of Hematology/Oncology, Translational Research Laboratory, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Subrahmanya D Vallabhapurapu
- Division of Hematology/Oncology, Translational Research Laboratory, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Zhengtao Chu
- Division of Hematology/Oncology, Translational Research Laboratory, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Swarajya L Vallabhapurapu
- Division of Hematology/Oncology, Translational Research Laboratory, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Robert S Franco
- Division of Hematology/Oncology, Translational Research Laboratory, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Michelle Mierzwa
- Department of Radiation Oncology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - William Kassing
- Department of Radiation Oncology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - William L Barrett
- Department of Radiation Oncology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Xiaoyang Qi
- Division of Hematology/Oncology, Translational Research Laboratory, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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10
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Sharma B, Kanwar SS. Phosphatidylserine: A cancer cell targeting biomarker. Semin Cancer Biol 2018; 52:17-25. [DOI: 10.1016/j.semcancer.2017.08.012] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/12/2017] [Accepted: 08/30/2017] [Indexed: 12/11/2022]
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11
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Blanco VM, Chu Z, LaSance K, Gray BD, Pak KY, Rider T, Greis KD, Qi X. Optical and nuclear imaging of glioblastoma with phosphatidylserine-targeted nanovesicles. Oncotarget 2017; 7:32866-75. [PMID: 27096954 PMCID: PMC5078058 DOI: 10.18632/oncotarget.8763] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 03/28/2016] [Indexed: 12/15/2022] Open
Abstract
Multimodal tumor imaging with targeted nanoparticles potentially offers both enhanced specificity and sensitivity, leading to more precise cancer diagnosis and monitoring. We describe the synthesis and characterization of phenol-substituted, lipophilic orange and far-red fluorescent dyes and a simple radioiodination procedure to generate a dual (optical and nuclear) imaging probe. MALDI-ToF analyses revealed high iodination efficiency of the lipophilic reporters, achieved by electrophilic aromatic substitution using the chloramide 1,3,4,6-tetrachloro-3α,6α-diphenyl glycoluril (Iodogen) as the oxidizing agent in an organic/aqueous co-solvent mixture. Upon conjugation of iodine-127 or iodine-124-labeled reporters to tumor-targeting SapC-DOPS nanovesicles, optical (fluorescent) and PET imaging was performed in mice bearing intracranial glioblastomas. In addition, tumor vs non-tumor (normal brain) uptake was compared using iodine-125. These data provide proof-of-principle for the potential value of SapC-DOPS for multimodal imaging of glioblastoma, the most aggressive primary brain tumor.
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Affiliation(s)
- Víctor M Blanco
- Division of Hematology-Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
| | - Zhengtao Chu
- Division of Hematology-Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA.,Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
| | - Kathleen LaSance
- Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
| | - Brian D Gray
- Molecular Targeting Technologies, Inc., West Chester, Pennsylvania 19380, USA
| | - Koon Yan Pak
- Molecular Targeting Technologies, Inc., West Chester, Pennsylvania 19380, USA
| | - Therese Rider
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
| | - Kenneth D Greis
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
| | - Xiaoyang Qi
- Division of Hematology-Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA.,Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
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Gruschus JM, Jiang Z, Yap TL, Hill SA, Grishaev A, Piszczek G, Sidransky E, Lee JC. Dissociation of glucocerebrosidase dimer in solution by its co-factor, saposin C. Biochem Biophys Res Commun 2015; 457:561-6. [PMID: 25600808 DOI: 10.1016/j.bbrc.2015.01.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 01/08/2015] [Indexed: 12/23/2022]
Abstract
Mutations in the gene for the lysosomal enzyme glucocerebrosidase (GCase) cause Gaucher disease and are the most common risk factor for Parkinson disease (PD). Analytical ultracentrifugation of 8 μM GCase shows equilibrium between monomer and dimer forms. However, in the presence of its co-factor saposin C (Sap C), only monomer GCase is seen. Isothermal calorimetry confirms that Sap C associates with GCase in solution in a 1:1 complex (Kd = 2.1 ± 1.1 μM). Saturation cross-transfer NMR determined that the region of Sap C contacting GCase includes residues 63-66 and 74-76, which is distinct from the region known to enhance GCase activity. Because α-synuclein (α-syn), a protein closely associated with PD etiology, competes with Sap C for GCase binding, its interaction with GCase was also measured by ultracentrifugation and saturation cross-transfer. Unlike Sap C, binding of α-syn to GCase does not affect multimerization. However, adding α-syn reduces saturation cross-transfer from Sap C to GCase, confirming displacement. To explore where Sap C might disrupt multimeric GCase, GCase x-ray structures were analyzed using the program PISA, which predicted stable dimer and tetramer forms. For the most frequently predicted multimer interface, the GCase active sites are partially buried, suggesting that Sap C might disrupt the multimer by binding near the active site.
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Affiliation(s)
- James M Gruschus
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD 20892, United States.
| | - Zhiping Jiang
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD 20892, United States
| | - Thai Leong Yap
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD 20892, United States
| | - Stephanie A Hill
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD 20892, United States
| | - Alexander Grishaev
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, United States
| | - Grzegorz Piszczek
- Biophysics Core, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Ellen Sidransky
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Jennifer C Lee
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD 20892, United States.
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13
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Winter P. Molecular Imaging at Nanoscale with Magnetic Resonance Imaging. Nanomedicine (Lond) 2014. [DOI: 10.1201/b17246-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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14
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Temporal changes in prosaposin expression in the rat dentate gyrus after birth. PLoS One 2014; 9:e95883. [PMID: 24871372 PMCID: PMC4037173 DOI: 10.1371/journal.pone.0095883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 04/01/2014] [Indexed: 11/29/2022] Open
Abstract
Neurogenesis in the hippocampal dentate gyrus occurs constitutively throughout postnatal life. Adult neurogenesis includes a multistep process that ends with the formation of a postmitotic and functionally integrated new neuron. During adult neurogenesis, various markers are expressed, including GFAP, nestin, Pax6, polysialic acid-neural cell adhesion molecule (PSA-NCAM), neuronal nuclei (NeuN), doublecortin, TUC-4, Tuj-1, and calretinin. Prosaposin is the precursor of saposins A–D; it is found in various organs and can be excreted. Strong prosaposin expression has been demonstrated in the developing brain including the hippocampus, and its neurotrophic activity has been proposed. This study investigated changes in prosaposin in the dentate gyrus of young and adult rats using double immunohistochemistry with antibodies to prosaposin, PSA-NCAM, and NeuN. Prosaposin immunoreactivity was intense in the dentate gyrus at postnatal day 3 (P3) and P7, but decreased gradually after P14. In the dentate gyrus at P28, immature PSA-NCAM-positive neurons localized exclusively in the subgranular zone were prosaposin-negative, whereas mature Neu-N-positive neurons were positive for prosaposin. Furthermore, these prosaposin-negative immature neurons were saposin B-positive, suggesting that the neurons take up and degrade prosaposin. In situ hybridization assays showed that prosaposin in the adult dentate gyrus is dominantly the Pro+9 type, a secreted type of prosaposin. These results imply that prosaposin secreted from mature neurons stimulates proliferation and maturation of immature neurons in the dentate gyrus.
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15
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Winter PM, Pearce J, Chu Z, McPherson CM, Takigiku R, Lee JH, Qi X. Imaging of brain tumors with paramagnetic vesicles targeted to phosphatidylserine. J Magn Reson Imaging 2014; 41:1079-87. [PMID: 24797437 DOI: 10.1002/jmri.24654] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/14/2014] [Accepted: 04/17/2014] [Indexed: 01/06/2023] Open
Abstract
PURPOSE To investigate paramagnetic saposin C and dioleylphosphatidylserine (SapC-DOPS) vesicles as a targeted contrast agent for imaging phosphatidylserine (PS) expressed by glioblastoma multiforme (GBM) tumors. MATERIALS AND METHODS Gd-DTPA-BSA/SapC-DOPS vesicles were formulated, and the vesicle diameter and relaxivity were measured. Targeting of Gd-DTPA-BSA/SapC-DOPS vesicles to tumor cells in vitro and in vivo was compared with nontargeted paramagnetic vesicles (lacking SapC). Mice with GBM brain tumors were imaged at 3, 10, 20, and 24 h postinjection to measure the relaxation rate (R1) in the tumor and the normal brain. RESULTS The mean diameter of vesicles was 175 nm, and the relaxivity at 7 Tesla was 3.32 (s*mM)(-1) relative to the gadolinium concentration. Gd-DTPA-BSA/SapC-DOPS vesicles targeted cultured cancer cells, leading to an increased R1 and gadolinium level in the cells. In vivo, Gd-DTPA-BSA/SapC-DOPS vesicles produced a 9% increase in the R1 of GBM brain tumors in mice 10 h postinjection, but only minimal changes (1.2% increase) in the normal brain. Nontargeted paramagnetic vesicles yielded minimal change in the tumor R1 at 10 h postinjection (1.3%). CONCLUSION These experiments demonstrate that Gd-DTPA-BSA/SapC-DOPS vesicles can selectively target implanted brain tumors in vivo, providing noninvasive mapping of the cancer biomarker PS.
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Affiliation(s)
- Patrick M Winter
- Department of Radiology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
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16
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Olowokure O, Qi X. Pancreatic cancer: current standards, working towards a new therapeutic approach. Expert Rev Anticancer Ther 2014; 14:495-7. [PMID: 24621210 DOI: 10.1586/14737140.2014.895937] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Pancreatic cancer is the fourth leading cause of cancer deaths with a 5-year survival of 4-6%. Clinical challenges remain to be addressed, since few promising approaches to treat pancreatic cancer have been reported. Here we discuss the potential of a new biotherapeutic agent composed of a lysosomal protein (Saposin C, SapC) and an acidic phospholipid (dioleoylphosphatidylserine, DOPS) which can be assembled into stable nanovesicles (SapC-DOPS) for tackling pancreatic cancer. Phosphatidylserine (PS) is a lipid biomarker on membrane surface of pancreatic cancer cells and can be effectively targeted by SapC-DOPS nanovesicles for cancer-selective therapy. SapC-DOPS nanovesicles have shown excellent pre-clinical therapeutic and safety profiles. Safety profiles which suggests that this new approach is potentially a viable option for pancreatic cancer therapy that is worthy of further clinical development.
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Affiliation(s)
- Olugbenga Olowokure
- University of Cincinnati - Hematology-Oncology, Internal Medicine, The Vontz Center for Molecular Studies 3125 Eden Avenue, Cincinnati, OH 45267-0508, USA
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17
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Gao HL, Li C, Nabeka H, Shimokawa T, Kobayashi N, Saito S, Wang ZY, Cao YM, Matsuda S. Decrease in prosaposin in the Dystrophic mdx mouse brain. PLoS One 2013; 8:e80032. [PMID: 24244600 PMCID: PMC3828254 DOI: 10.1371/journal.pone.0080032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/27/2013] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Duchenne muscular dystrophy caused by a mutation in the X-linked dystrophin gene induces metabolic and structural disorders in the brain. A lack of dystrophin in brain structures is involved in impaired cognitive function. Prosaposin (PS), a neurotrophic factor, is abundant in the choroid plexus and various brain regions. We investigated whether PS serves as a link between dystrophin loss and gross and/or ultrastructural brain abnormalities. METHODOLOGY/PRINCIPAL FINDINGS The distribution of PS in the brains of juvenile and adult mdx mice was investigated by immunochemistry, Western blotting, and in situ hybridization. Immunochemistry revealed lower levels of PS in the cytoplasm of neurons of the cerebral cortex, hippocampus, cerebellum, and choroid plexus in mdx mice. Western blotting confirmed that PS levels were lower in these brain regions in both juveniles and adults. Even with low PS production in the choroids plexus, there was no significant PS decrease in cerebrospinal fluid (CSF). In situ hybridization revealed that the primary form of PS mRNA in both normal and mdx mice was Pro+9, a secretory-type PS, and the hybridization signals for Pro+9 in the above-mentioned brain regions were weaker in mdx mice than in normal mice. We also investigated mitogen-activated protein kinase signalling. Stronger activation of ERK1/2 was observed in mdx mice, ERK1/2 activity was positively correlated with PS activity, and exogenous PS18 stimulated both p-ERK1/2 and PS in SH-SY5Y cells. CONCLUSIONS/SIGNIFICANCE Low levels of PS and its receptors suggest the participation of PS in some pathological changes in the brains of mdx mice.
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Affiliation(s)
- Hui-ling Gao
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Cheng Li
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
- Department of Immunology, China Medical University, Shenyang, China
| | - Hiroaki Nabeka
- 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
| | - Naoto Kobayashi
- Medical Education Center, 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
| | - Zhan-You Wang
- College of Life and Health Sciences, Northeastern University, Shenyang, China
| | - Ya-ming Cao
- Department of Immunology, China Medical University, Shenyang, China
| | - Seiji Matsuda
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
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Chu Z, Abu-Baker S, Palascak MB, Ahmad SA, Franco RS, Qi X. Targeting and cytotoxicity of SapC-DOPS nanovesicles in pancreatic cancer. PLoS One 2013; 8:e75507. [PMID: 24124494 PMCID: PMC3790873 DOI: 10.1371/journal.pone.0075507] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/14/2013] [Indexed: 01/05/2023] Open
Abstract
Only a small number of promising drugs target pancreatic cancer, which is the fourth leading cause of cancer deaths with a 5-year survival of less than 5%. Our goal is to develop a new biotherapeutic agent in which a lysosomal protein (saposin C, SapC) and a phospholipid (dioleoylphosphatidylserine, DOPS) are assembled into nanovesicles (SapC-DOPS) for treating pancreatic cancer. A distinguishing feature of SapC-DOPS nanovesicles is their high affinity for phosphatidylserine (PS) rich microdomains, which are abnormally exposed on the membrane surface of human pancreatic tumor cells. To evaluate the role of external cell PS, in vitro assays were used to correlate PS exposure and the cytotoxic effect of SapC-DOPS in human tumor and nontumorigenic pancreatic cells. Next, pancreatic tumor xenografts (orthotopic and subcutaneous models) were used for tumor targeting and therapeutic efficacy studies with systemic SapC-DOPS treatment. We observed that the nanovesicles selectively killed human pancreatic cancer cells in vitro by inducing apoptotic death, whereas untransformed cells remained unaffected. This in vitro cytotoxic effect correlated to the surface exposure level of PS on the tumor cells. Using xenografts, animals treated with SapC-DOPS showed clear survival benefits and their tumors shrank or disappeared. Furthermore, using a double-tracking method in live mice, we showed that the nanovesicles were specifically targeted to orthotopically-implanted, bioluminescent pancreatic tumors. These data suggest that the acidic phospholipid PS is a biomarker for pancreatic cancer that can be effectively targeted for therapy utilizing cancer-selective SapC-DOPS nanovesicles. This study provides convincing evidence in support of developing a new therapeutic approach to pancreatic cancer.
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Affiliation(s)
- Zhengtao Chu
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Shadi Abu-Baker
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Mary B. Palascak
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Syed A. Ahmad
- Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Robert S. Franco
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Xiaoyang Qi
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
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Attenuation of MPTP/MPP(+) toxicity in vivo and in vitro by an 18-mer peptide derived from prosaposin. Neuroscience 2013; 236:373-93. [PMID: 23321539 DOI: 10.1016/j.neuroscience.2013.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 12/29/2012] [Accepted: 01/08/2013] [Indexed: 01/23/2023]
Abstract
Parkinson's disease (PD) is a chronic progressive neurological disorder with an increasing incidence in the aging population. Neuroprotective and/or neuroregenerative strategies remain critical in the treatment of this increasingly prevalent disease. Prosaposin is a neurotrophic factor whose neurotrophic activity is attributed to a stretch of 12 amino acids located at the N-terminal region of saposin C. The present study was performed to investigate the protective effect and mechanism of action of a prosaposin-derived 18-mer peptide (PS18: LSELIINNATEELLIKGL) in Parkinson's disease models. We used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 1-methyl-4-phenylpyridinium ion (MPP(+))-induced dopaminergic neurotoxicity in C57BL/6J mice or SH-SY5Y cells and explored the protective effect and mechanisms of action of PS18 on dopaminergic neurons. Treatment with 2.0mg/kg PS18 significantly improved behavioral deficits, enhanced the survival of tyrosine hydroxylase-positive neurons, and decreased the activity of astrocytes in the substantia nigra and striatum in MPTP-induced PD model mice. In vitro, a Cell Counting Kit-8 assay and Hoechst 33258 staining revealed that co-treatment with 300ng/mL PS18 and 5mM MPP(+) protected against MPP(+)-induced nuclear morphological changes and attenuated cell death induced by MPP(+). We also found that PS18-FAM entered the cells, and the retention time of PS18-FAM in the cytoplasm of MPP(+)-treated cells was shorter than that of untreated cells. In addition, PS18 showed protection from MPP(+)/MPTP-induced apoptosis in the SH-SY5Y cells and dopaminergic neurons in the PD model mice via suppression of the c-Jun N-terminal kinase/c-Jun pathway; upregulation of Bcl-2; downregulation of BAX, attenuating mitochondrial damage; and inhibition of caspase-3. These findings suggest that PS18 may provide a valuable therapeutic strategy for the treatment of progressive neurodegenerative diseases such as PD.
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Akil O, Lustig LR. Severe vestibular dysfunction and altered vestibular innervation in mice lacking prosaposin. Neurosci Res 2012; 72:296-305. [PMID: 22326583 DOI: 10.1016/j.neures.2012.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 01/06/2012] [Accepted: 01/25/2012] [Indexed: 11/25/2022]
Abstract
Prosaposin, a precursor of four glycoprotein activators (saposin A, B, C and D) for lysosomal hydrolases, has previously been shown to be important for normal adult cochlear innervation and the maintenance of normal hearing. In these studies, we now investigate prosaposin in normal vestibular epithelium and the functional impairment of balance caused by prosaposin ablation. In normal mice, prosaposin is localized to all 3 vestibular end-organs (ampullae, saccule, and utricle) and Scarpa's ganglion by RT-PCR, Western blot analysis and immunofluorescence. Ablation of prosaposin function caused severe vestibular dysfunction on a battery of behavioral tasks. Histologically, the KO mice demonstrated an exuberant cellular proliferation below the vestibular hair cells with disruption of the supporting cells. Electron microscopy further demonstrated inclusion bodies and cellular proliferation disturbing the normal neuroepithelial structure of the vestibular end-organs. Lastly, immunofluorescence (neurofilament 200 and synaptophysin) staining suggests that this cellular proliferation corresponds to afferent and efferent neuronal overgrowth. These data suggest that prosaposin plays a role not only in the maintenance of normal hearing but also an important role in the neuronal maturation processes of the vestibular sensory epithelium and the maintenance of normal vestibular system function.
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Affiliation(s)
- Omar Akil
- Department of Otolaryngology-Head & Neck Surgery, University of California San Francisco, San Francisco, CA 94143-0449, United States.
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Abu-Baker S, Chu Z, Stevens AM, Li J, Qi X. Cytotoxicity and Selectivity in Skin Cancer by SapC-DOPS Nanovesicles. ACTA ACUST UNITED AC 2012; 3:321-326. [PMID: 25485166 DOI: 10.4236/jct.2012.34041] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Squamous cell carcinoma (SCC) and melanoma are malignant human cancers of the skin with an annual mortality that exceed 10,000 cases every year in the USA alone. In this study, the lysosomal protein saposin C (SapC) and the phospholipid dioloylphosphatidylserine (DOPS) were assembled into cancer-selective nanovesicles (SapC-DOPS) and successfully tested using several in vitro and in vivo skin cancer models. Using MTT assay that measures the percentage of cell death, SapC-DOPS cytotoxic effect on three skin tumor cell lines (squamous cell carcinoma, SK-MEL-28, and MeWo) was compared to two normal nontumorigenic skin cells lines, normal immortalized keratinocyte (NIK) and human fibroblast cell (HFC). We observed that the nanovesicles selectively killed the skin cancer cells by inducing apoptotic cell death whereas untransformed skin cancer cells remained unaffected. Using subcutaneous skin tumor xenografts, animals treated with SapC-DOPS by subcutaneous injection showed a 79.4 % tumor reduced compared to the control after 4 days of treatment. We observed that the nanovesicles killed skin cancer cells by inducing apoptotic cell death compared to the control as revealed by TUNEL staining of xenograft tumor sections.
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Affiliation(s)
- Shadi Abu-Baker
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH
| | - Zhengtao Chu
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH ; Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Ashley M Stevens
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH ; Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Jie Li
- Department of Dermatology, University of Miami, Miami, FL
| | - Xiaoyang Qi
- Division of Hematology/Oncology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH ; Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
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Lieberman RL. A Guided Tour of the Structural Biology of Gaucher Disease: Acid-β-Glucosidase and Saposin C. Enzyme Res 2011; 2011:973231. [PMID: 22145077 PMCID: PMC3226326 DOI: 10.4061/2011/973231] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/07/2011] [Indexed: 01/27/2023] Open
Abstract
Mutations in both acid-β-glucosidase (GCase) and saposin C lead to Gaucher disease, the most common lysosomal storage disorder. The past several years have seen an explosion of structural and biochemical information for these proteins, which have provided new insight into the biology and pathogenesis of Gaucher disease, as well as opportunities for new therapeutic directions. Nearly 20 crystal structures of GCase are now available, from different heterologous sources, complexed with different ligands in the active site, in different glycosylation states, as well as one that harbors a prevalent disease-causing mutation, N370S. For saposin C, two NMR and 3 crystal structures have been solved, each with its unique snapshot. This review focuses on the details of these structures to highlight salient common and disparate features that contribute to our current state of knowledge of this complex orphan disease.
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Affiliation(s)
- Raquel L. Lieberman
- School of Chemistry & Biochemistry, Institute for Bioscience and Bioengineering, Georgia Institute of Technology, 901 Atlantic Drive NW Atlanta, GA 30332-0400, 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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Qi X, Chu Z, Mahller YY, Stringer KF, Witte DP, Cripe TP. Cancer-selective targeting and cytotoxicity by liposomal-coupled lysosomal saposin C protein. Clin Cancer Res 2009; 15:5840-51. [PMID: 19737950 DOI: 10.1158/1078-0432.ccr-08-3285] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE Saposin C is a multifunctional protein known to activate lysosomal enzymes and induce membrane fusion in an acidic environment. Excessive accumulation of lipid-coupled saposin C in lysosomes is cytotoxic. Because neoplasms generate an acidic microenvironment, caused by leakage of lysosomal enzymes and hypoxia, we hypothesized that saposin C may be an effective anticancer agent. We investigated the antitumor efficacy and systemic biodistribution of nanovesicles comprised of saposin C coupled with dioleoylphosphatidylserine in preclinical cancer models. EXPERIMENTAL DESIGN Neuroblastoma, malignant peripheral nerve sheath tumor and, breast cancer cells were treated with saposin C-dioleoylphosphatidylserine nanovesicles and assessed for cell viability, ceramide elevation, caspase activation, and apoptosis. Fluorescently labeled saposin C-dioleoylphosphatidylserine was i.v. injected to determine in vivo tumor-targeting specificity. Antitumor activity and toxicity profile of saposin C-dioleoylphosphatidylserine were evaluated in xenograft models. RESULTS Saposin C-dioleoylphosphatidylserine nanovesicles, with a mean diameter of approximately 190 nm, showed specific tumor-targeting activity shown through in vivo imaging. Following i.v. administration, saposin C-dioleoylphosphatidylserine nanovesicles preferentially accumulated in tumor vessels and cells in tumor-bearing mice. Saposin C-dioleoylphosphatidylserine induced apoptosis in multiple cancer cell types while sparing normal cells and tissues. The mechanism of saposin C-dioleoylphosphatidylserine induction of apoptosis was determined to be in part through elevation of intracellular ceramides, followed by caspase activation. In in vivo models, saposin C-dioleoylphosphatidylserine nanovesicles significantly inhibited growth of preclinical xenografts of neuroblastoma and malignant peripheral nerve sheath tumor. I.v. dosing of saposin C-dioleoylphosphatidylserine showed no toxic effects in nontumor tissues. CONCLUSIONS Saposin C-dioleoylphosphatidylserine nanovesicles offer promise as a novel, nontoxic, cancer-targeted, antitumor agent for treating a broad range of cancers.
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Affiliation(s)
- Xiaoyang Qi
- Division and Program in HumanGenetics, 3333 Burnet Avenue, Cincinnati, Ohio 45229-3039, USA.
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25
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CHU ZHENGTAO, SUN YING, KUAN CHIAYI, GRABOWSKI GREGORYA, QI XIAOYANG. Saposin C: Neuronal Effect and CNS Delivery by Liposomes. Ann N Y Acad Sci 2008. [DOI: 10.1111/j.1749-6632.2005.tb00031.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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26
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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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27
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Sikora J, Harzer K, Elleder M. Neurolysosomal pathology in human prosaposin deficiency suggests essential neurotrophic function of prosaposin. Acta Neuropathol 2007; 113:163-75. [PMID: 17024494 PMCID: PMC2956888 DOI: 10.1007/s00401-006-0148-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 08/15/2006] [Accepted: 08/29/2006] [Indexed: 01/27/2023]
Abstract
A neuropathologic study of three cases of prosaposin (pSap) deficiency (ages at death 27, 89 and 119 days), carried out in the standard autopsy tissues, revealed a neurolysosomal pathology different from that in the non-neuronal cells. Non-neuronal storage is represented by massive lysosomal accumulation of glycosphingolipids (glucosyl-, galactosyl-, lactosyl-, globotriaosylceramides, sulphatide, and ceramide). The lysosomes in the central and peripheral neurons were distended by pleomorphic non-lipid aggregates lacking specific staining and autofluorescence. Lipid storage was borderline in case 1, and at a low level in the other cases. Neurolysosomal storage was associated with massive ubiquitination, which was absent in the non-neuronal cells and which did not display any immunohistochemical aggresomal properties. Confocal microscopy and cross-correlation function analyses revealed a positive correlation between the ubiquitin signal and the late endosomal/lysosomal markers. We suppose that the neuropathology most probably reflects excessive influx of non-lipid material (either in bulk or as individual molecules) into the neurolysosomes. The cortical neurons appeared to be uniquely vulnerable to pSap deficiency. Whereas in case 1 they populated the cortex, in cases 2 and 3 they had been replaced by dense populations of both phagocytic microglia and astrocytes. We suggest that this massive neuronal loss reflects a cortical neuronal survival crisis precipitated by the lack of pSap. The results of our study may extend the knowledge of the neurotrophic function of pSap, which should be considered essential for the survival and maintenance of human cortical neurons.
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Affiliation(s)
- Jakub Sikora
- Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University and General Teaching Hospital, Ke Karlovu 2, Prague 2, 12808 Czech Republic
| | - Klaus Harzer
- Neurometabolic Laboratory, Department of Pediatrics and Child Development (Universitäts-Kinderklinik), University of Tübingen, Tübingen, 72076 Germany
| | - Milan Elleder
- Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University and General Teaching Hospital, Ke Karlovu 2, Prague 2, 12808 Czech Republic
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28
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Akil O, Chang J, Hiel H, Kong JH, Yi E, Glowatzki E, Lustig LR. Progressive deafness and altered cochlear innervation in knock-out mice lacking prosaposin. J Neurosci 2007; 26:13076-88. [PMID: 17167097 PMCID: PMC6674959 DOI: 10.1523/jneurosci.3746-06.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
After a yeast two-hybrid screen identified prosaposin as a potential interacting protein with the nicotinic acetylcholine receptor (nAChR) subunit alpha10, studies were performed to characterize prosaposin in the normal rodent inner ear. Prosaposin demonstrates diffuse organ of Corti expression at birth, with gradual localization to the inner hair cells (IHCs) and its supporting cells, inner pillar cells, and synaptic region of the outer hair cells (OHCs) and Deiters' cells (DCs) by postnatal day 21 (P21). Microdissected OHC and DC quantitative reverse transcriptase-PCR and immunohistology localizes prosaposin mRNA to DCs and OHCs, and protein predominantly to the apex of the DCs. Subsequent studies in a prosaposin knock-out (KO) (-/-) mouse showed intact but slightly reduced hearing through P19, but deafness by P25 and reduced distortion product otoacoustic emissions from P15 onward. Beginning at P12, the prosaposin KO mice showed histologic organ of Corti changes including cellular hypertrophy in the region of the IHC and greater epithelial ridge, a loss of OHCs from cochlear apex, and vacuolization of OHCs. Immunofluorescence revealed exuberant overgrowth of auditory afferent neurites in the region of the IHCs and proliferation of auditory efferent neurites in the region of the tunnel of Corti. IHC recordings from these KO mice showed normal I-V curves and responses to applied acetylcholine. Together, these results suggest that prosaposin helps maintain normal innervation patterns to the organ of Corti. Furthermore, prosaposin's overlapping developmental expression pattern and binding capacity toward the nAChR alpha10 suggest that alpha10 may also play a role in this function.
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MESH Headings
- Acoustic Stimulation/methods
- Animals
- Animals, Newborn
- Cochlea/embryology
- Cochlea/innervation
- Cochlea/metabolism
- Cochlea/ultrastructure
- Deafness/genetics
- Deafness/metabolism
- Deafness/physiopathology
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory/metabolism
- Hair Cells, Auditory/ultrastructure
- Hair Cells, Auditory, Inner/embryology
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Outer/embryology
- Hair Cells, Auditory, Outer/metabolism
- Mice
- Mice, Knockout
- Organ of Corti/metabolism
- Organ of Corti/ultrastructure
- Rats
- Rats, Sprague-Dawley
- Saposins/deficiency
- Saposins/genetics
- Saposins/physiology
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Affiliation(s)
- Omar Akil
- Department of Otolaryngology–Head and Neck Surgery, University of California, San Francisco, San Francisco, California 94143-0449
| | - Jolie Chang
- Department of Otolaryngology–Head and Neck Surgery, University of California, San Francisco, San Francisco, California 94143-0449
| | - Hakim Hiel
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland 21287, and
| | - Jee-Hyun Kong
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Eunyoung Yi
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland 21287, and
| | - Elisabeth Glowatzki
- Department of Otolaryngology–Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland 21287, and
| | - Lawrence R. Lustig
- Department of Otolaryngology–Head and Neck Surgery, University of California, San Francisco, San Francisco, California 94143-0449
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29
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Ahtiainen L, Luiro K, Kauppi M, Tyynelä J, Kopra O, Jalanko A. Palmitoyl protein thioesterase 1 (PPT1) deficiency causes endocytic defects connected to abnormal saposin processing. Exp Cell Res 2006; 312:1540-53. [PMID: 16542649 DOI: 10.1016/j.yexcr.2006.01.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 01/17/2006] [Accepted: 01/18/2006] [Indexed: 11/16/2022]
Abstract
Infantile neuronal ceroid lipofuscinosis (INCL) is a severe neurodegenerative disorder of the childhood caused by mutations in the gene encoding palmitoyl protein thioesterase 1 (PPT1). PPT1 localizes to late endosomes/lysosomes of non-neuronal cells and in neurons also to presynaptic areas. PPT1-deficiency causes massive death of cortical neurons and most tissues show an accumulation of saposins A and D. We have here studied endocytic pathways, saposin localization and processing in PPT1-deficient fibroblasts to elucidate the cellular defects resulting in accumulation of specific saposins. We show that PPT1-deficiency causes a defect in fluid-phase and receptor-mediated endocytosis, whereas marker uptake and recycling endocytosis remain intact. Furthermore, we show that saposins A and D are more abundant and relocalized in PPT-deficient fibroblasts and mouse primary neurons. Metabolic labeling and immunoprecipitation analyses revealed hypersecretion and abnormal processing of prosaposin, implying that the accumulation of saposins may result from endocytic defects. We show for the first time a connection between saposin storage and a defect in the endocytic pathway of INCL cells. These data provide new insights into the metabolism of PPT1-deficient cells and offer a basis for further studies on cellular processes causing neuronal death in INCL and other neurodegenerative diseases.
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Affiliation(s)
- Laura Ahtiainen
- National Public Health Institute, Department of Molecular Medicine, Biomedicum Helsinki, P.O. Box 104, 00251 Helsinki, Finland
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30
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Liou B, Kazimierczuk A, Zhang M, Scott CR, Hegde RS, Grabowski GA. Analyses of variant acid beta-glucosidases: effects of Gaucher disease mutations. J Biol Chem 2005; 281:4242-53. [PMID: 16293621 DOI: 10.1074/jbc.m511110200] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Acid beta-glucosidase (GCase) is a 497-amino acid, membrane-associated lysosomal exo-beta-glucosidase whose defective activity leads to the Gaucher disease phenotypes. To move toward a structure/function map for disease mutations, 52 selected single amino acid substitutions were introduced into GCase, expressed in an insect cell system, purified, and characterized for basic kinetic, stability, and activator response properties. The variant GCases from Gaucher disease patients and selected variant GCases from the mouse had decreased relative k(cat) and differential effects on active site binding and/or attachment of mechanism-based covalent (conduritol B epoxide) or reversible (deoxynojirimycin derivatives) inhibitors. A defect in negatively charged phospholipid activation was present in the majority of variant GCases but was increased in two, N370S and V394L. Deficits in saposin C enhancement of k(cat) were present in variant GCases involving residues 48-122, whereas approximately 2-fold increases were obtained with the L264I GCase. About 50% of variant GCases each had wild-type or increased sensitivity to in vitro cathepsin D digestion. Mapping of these properties onto the crystal structures of GCase indicated wide dispersion of functional properties that can affect catalytic function and stability. Site-directed mutagenesis of cysteine residues showed that the disulfide bonds, Cys(4)-Cys(16) and Cys(18)-Cys(23), and a free Cys(342) were essential for activity; the free Cys(126) and Cys(248) were not. Relative k(cat) was highly sensitive to a His substitution at Arg(496) but not at Arg(495). These studies and high phylogenetic conservation indicate localized and general structural effects of Gaucher disease mutations that were not obvious from the nature of the amino acid substitution, including those predicted to be nondisruptive (e.g. Val --> Leu). These results provide initial studies for the engineering of variant GCases and, potentially, molecular chaperones for therapeutic use.
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Affiliation(s)
- Benjamin Liou
- Division and Program in Human Genetics, Children's Hospital Research Foundation, Cincinnati, OH 45229, USA
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31
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Cohen T, Ravid L, Altman N, Madar-Shapiro L, Fein A, Weil M, Horowitz M. Conservation of expression and alternative splicing in the prosaposin gene. ACTA ACUST UNITED AC 2005; 129:8-19. [PMID: 15469878 DOI: 10.1016/j.molbrainres.2004.06.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2004] [Indexed: 10/26/2022]
Abstract
Prosaposin is the precursor of four lysosomal activator molecules known as saposins A, B, C and D. It is also secreted and was proposed to be a neurotrophic factor. The neurotrophic function was attributed to the amino terminus of saposin C. In man, mouse and rat prosaposin is transcribed to two major isoforms differing in the inclusion of 9 bps of exon 8 within the saposin B domain. In the present study, we show that there is evolutionary conservation of the prosaposin structure and alternative splicing in chick and zebrafish as well. Moreover, there is conservation in prosaposin expression as tested immunohistochemically in the mouse and chick developing brain. We developed a sensitive assay to quantitate the prosaposin alternatively spliced forms. Our results indicate that, in mouse brain, skeletal and cardiac muscle the exon 8-containing RNA is most abundant, while it is almost absent from visceral and smooth muscle-containing organs. We observed temporal and differential expression of the alternatively spliced prosaposin mRNAs in mouse and chick brain as well as during development. The elevation in the abundance of exon 8-containing prosaposin RNA during mouse and chick brain development may suggest a role for the exon 8-containing prosaposin form in this process.
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Affiliation(s)
- Tsadok Cohen
- Department of Cell Research and Immunology, Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
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32
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Misasi R, Garofalo T, Di Marzio L, Mattei V, Gizzi C, Hiraiwa M, Pavan A, Grazia Cifone M, Sorice M. Prosaposin: a new player in cell death prevention of U937 monocytic cells. Exp Cell Res 2004; 298:38-47. [PMID: 15242760 DOI: 10.1016/j.yexcr.2004.04.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 04/02/2004] [Indexed: 01/24/2023]
Abstract
We report that prosaposin binds to U937 and is active as a protective factor on tumor necrosis factor alpha (TNFalpha)-induced cell death. The prosaposin-derived saposin C binds to U937 cells in a concentration-dependent manner, suggesting that prosaposin behaves similarly. Prosaposin binding induces U937 cell death prevention, reducing both necrosis and apoptosis. This effect was inhibited by mitogen-activated protein ERK kinase (MEK) and sphingosine kinase (SK) inhibitors, indicating that prosaposin prevents cell apoptosis by activation of extracellular signal-regulated kinases (ERKs) and sphingosine kinase. Prosaposin led to rapid ERK phosphorylation in U937 cells as detected by anti-phospho-p44/42 mitogen-activated protein (MAP) kinase and anti-phosphotyrosine reactivity on ERK immunoprecipitates. It was partially prevented by apo B-100 and pertussis toxin (PT), suggesting that both lipoprotein receptor-related protein (LRP) receptor and Go-coupled receptor may play a role in the prosaposin-triggered pathway. Moreover, sphingosine kinase activity was increased by prosaposin treatment as demonstrated by the enhanced intracellular formation of sphingosine-1-phosphate (S-1-P). The observation that the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin prevented the prosaposin effect on cell apoptosis suggests that sphingosine kinase exerts its anti-apoptotic activity by the PI3K-Akt pathway. Thus, cell apoptosis prevention by prosaposin occurs through ERK phosphorylation and sphingosine kinase. The biological effect triggered by prosaposin might be extended to primary cells because it triggers Erk phosphorylation in peripheral blood mononuclear cells (PBMCs). This is the first evidence of a biological effect consequent to a signal transduction pathway triggered by prosaposin in cells of non-neurological origin.
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Affiliation(s)
- Roberta Misasi
- Dipartimento di Medicina Sperimentale e Patologia, Università La Sapienza, Roma, Rome, Italy.
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33
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Jura J, Wegrzyn P, Zarebski A, Władyka B, Koj A. Identification of changes in the transcriptome profile of human hepatoma HepG2 cells stimulated with interleukin-1 beta. Biochim Biophys Acta Mol Basis Dis 2004; 1689:120-33. [PMID: 15196593 DOI: 10.1016/j.bbadis.2004.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2003] [Revised: 02/27/2004] [Accepted: 03/02/2004] [Indexed: 10/26/2022]
Abstract
Interleukin-1 (IL-1) is the principal pro-inflammatory cytokine participating in the initiation of acute phase response. Human hepatoma HepG2 cells were exposed to 15 ng/ml of IL-1beta for times ranging from 1 to 24 h and the total RNA was isolated. Then cDNA was obtained and used for differential display with 10 arbitrary primers and 9 oligo(dT) primers designed by Clontech. Validation of observed changes of differentially expressed known genes was carried out by RT-PCR or Northern blot analysis. Out of 90 cDNA strands modulated by IL-1, 46 have been successfully reamplified and their sequencing indicates that they represent 36 different cDNA templates. By GenBank search, 26 cDNA clones were identified as already known genes while 10 showed no homology to any known gene. The identified transcripts modulated by IL-1 in HepG2 cells code for intracellular proteins of various function: trafficking/motor proteins (3 genes), proteins participating in the translation machinery or posttranscriptional/posttranslational modifications (7 genes), proteases (1 gene), proteins involved in metabolism (6 genes), activity modulators (3 genes), proteins of the cell cycle machinery (2 genes) and those functionally unclassified (4 genes). Majority of genes responded to IL-1 within 1 to 6 h (early genes), while two were late response genes (12-24 h) and four showed prolonged response over the whole 24-h period. Most of the observed changes of expression were in the range of two- to threefold increase in comparison to control untreated cells. Among identified genes, no typical secretory acute phase protein was found. The obtained results suggest that IL-1 affects the expression of several genes in HepG2 cells, especially those engaged in the synthesis and modifications of proteins.
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Affiliation(s)
- Jolanta Jura
- Department of Cell Biochemistry, Faculty of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Cracow, Poland
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34
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Carlson KA, Ciborowski P, Schellpeper CN, Biskup TM, Shen RF, Luo X, Destache CJ, Gendelman HE. Proteomic fingerprinting of HIV-1-infected human monocyte-derived macrophages: a preliminary report. J Neuroimmunol 2004; 147:35-42. [PMID: 14741425 DOI: 10.1016/j.jneuroim.2003.10.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Mononuclear phagocytes (MP; blood monocytes, alveolar, lymph node, and brain macrophages and microglia) are vehicles for dissemination and principle target cells for human immunodeficiency virus type 1 (HIV-1) infection. Notably, viral persistence in macrophages occurs despite ongoing phagocytic, intracellular killing, innate and adaptive immune responses. To assess potential pathways for how HIV-1 may bypass antiviral MP responses, we used proteomic tests to evaluate protein fingerprints of HIV-1-infected human monocyte-derived macrophages 7 days after viral infection. By using weak cation exchange chips, 58 proteins were found up- or down-regulated after HIV-1(ADA) infection. Several of these proteins were identified by microsequencing. It is probable that cellular proteins identified by proteomic fingerprinting could assist in unraveling how persistent viral infection occurs in MP lineage cells. Moreover, this evolving technology can be utilized to unravel changes in immune activities initiated by interactions between virus, environmental cues and drugs of abuse.
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Affiliation(s)
- Kimberly A Carlson
- Center for Neurovirology and Neurodegenerative Disorders, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198-5215, USA
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35
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Bornhauser BC, Olsson PA, Lindholm D. MSAP is a novel MIR-interacting protein that enhances neurite outgrowth and increases myosin regulatory light chain. J Biol Chem 2003; 278:35412-20. [PMID: 12826659 DOI: 10.1074/jbc.m306271200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Dynamic interactions between the actin cytoskeleton and specific proteins are crucial for changes in cell shape and motility. Here we describe a novel protein MSAP (MIR-interacting saposin-like protein) that is a positive regulator of neurite outgrowth. MSAP is expressed in different tissues, including brain, and has an apparent molecular weight of 21 kDa. MSAP interacts with the ezrin-radixin-moesin (ERM)-like myosin regulatory light chain-interacting protein (MIR), and the two proteins are co-localized in cell lines and in primary neurons. Overexpression of MSAP enhances neurite out-growth in neuroblastoma and PC12 cells, whereas down-regulation of MSAP using RNA silencing led to inhibition of neurite formation. The stimulation of neurite outgrowth by MSAP was abrogated by the overexpression of MIR, which induced a decrease in the levels of myosin regulatory light chain (MRLC). This reduction in MRLC by MIR was inhibited by blocking the activity of proteasome and by overexpression of MSAP, suggesting an effect on protein stability. Evidence was obtained that MIR decreases MRLC by inducing its ubiquitination. The results show that the levels of MRLC are controlled by MIR via ubiquitination and that the effect of MIR on MRLC is counteracted in the presence of MSAP. MSAP can stabilize MRLC and thus bring about an increase in neurite outgrowth.
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Affiliation(s)
- Beat C Bornhauser
- Department of Neuroscience and Neurobiology, Uppsala University, Biomedical Center, Box 587, S-75123 Uppsala, Sweden
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36
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Hiraiwa M, Liu J, Lu AG, Wang CY, Misasi R, Yamauchi T, Hozumi I, Inuzuka T, O'Brien JS. Regulation of gene expression in response to brain injury: enhanced expression and alternative splicing of rat prosaposin (SGP-1) mRNA in injured brain. J Neurotrauma 2003; 20:755-65. [PMID: 12965054 DOI: 10.1089/089771503767869980] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Prosaposin, the precursor of saposins or saps, is an injury-repair protein that acts on both neurons and glia. Previous studies identified the prosaposin gene as one of differentially expressed genes following nerve injury. In the present study, we investigated expression of prosaposin mRNA in injured brain utilizing rat models of focal cerebral ischemia and cortical stab wound in order to explore the significance of prosaposin in nerve injury. In ischemic brain, the level of prosaposin mRNA was elevated greater than 400% over controls within 5 days after ischemic insults. Importantly, this induction was accompanied by a 9-base splicing consistent with the alternative Exon-8 splicing of human prosaposin mRNA. In normal brain, two prosaposin mRNA species with and without the 9-base insertion were expressed at a ratio of 85:15; however, this equilibrium reverted to 5:95 following ischemic injury. Similar inductions were observed in stab wound brains. Immunohistochemical staining and in situ hybridization demonstrated an enhanced signal distribution of prosaposin mRNA and injury-induced prosaposin protein around the lesion. The data suggest the expression and processing of prosaposin mRNA may be crucially regulated not only for cerebral homeostasis but also during nerve regenerative and degenerative processes.
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Affiliation(s)
- Masao Hiraiwa
- Department of Neurosciences, School of Medicine, Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093-0634, USA.
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37
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Sun Y, Witte DP, Jin P, Grabowski GA. Analyses of temporal regulatory elements of the prosaposin gene in transgenic mice. Biochem J 2003; 370:557-66. [PMID: 12467496 PMCID: PMC1223203 DOI: 10.1042/bj20021120] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2002] [Revised: 11/19/2002] [Accepted: 12/06/2002] [Indexed: 11/17/2022]
Abstract
The expression of prosaposin is temporally and spatially regulated at transcriptional and post-translational levels. Transgenic mice with various 5'-flanking deletions of the prosaposin promoter fused to luciferase (LUC) reporters were used to define its temporal regulatory region. LUC expression in the transgenic mice carrying constructs with 234 bp (234LUC), 310 bp (310LUC) or 2400 bp (2400LUC) of the 5'-flanking region was analysed in the central nervous system and eye throughout development. For 310LUC and 2400LUC, low-level LUC activity was maintained until embryonal day 18 in brain, eye and spinal cord. The peak level of LUC activity was at birth, with return to a plateau (1/3 of peak) throughout adulthood. Deletion of the region that included the retinoic acid-receptor-related orphan receptor (ROR alpha)-binding site and sequence-specific transcription factor (Sp1) cluster sites (44-310 bp) suppressed the peak of activity. By comparison, the peak level for 234LUC was shifted 2 weeks into neonatal life in the brain, but not in the eye, and no peak of activity was observed in the spinal cord. The endogenous prosaposin mRNA in eye, spinal cord and cerebellum had low-level expression before birth and continued to increase into adulthood. In cerebrum, the endogenous mRNA showed similar expression profile to constructs 310LUC, 2400LUC and 234LUC, with the peak expression at 1 week and a decreased level in adult. In the brain of the newborn, 2400LUC was highly expressed in the trigeminal ganglion and brain stem regions when compared with the generalized expression pattern for endogenous prosaposin mRNA. These results suggest that the modifiers (ROR alpha- and Sp1-binding sites) residing within 310 bp of the 5'-flanking region mediate developmental regulation in the central nervous system and eye. Additional regulatory elements outside the 5' region of the 2400 bp promoter fragment appear to be essential for the physiological control of the prosaposin locus.
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Affiliation(s)
- Ying Sun
- The Division and Program in Human Genetics, Children's Hospital Medical Center, 3333 Burnet Avenue, PAV 3-52, Cincinnati, OH 45229-3039, USA
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38
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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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Sun Y, Qi X, Witte DP, Ponce E, Kondoh K, Quinn B, Grabowski GA. Prosaposin: threshold rescue and analysis of the "neuritogenic" region in transgenic mice. Mol Genet Metab 2002; 76:271-86. [PMID: 12208132 DOI: 10.1016/s1096-7192(02)00114-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Prosaposin is the precursor of four glycoprotein activators (saposins) for lysosomal hydrolases. Intact prosaposin also has lipid transfer properties in vitro as well as neuritogenic effects ex vivo and in vivo. Such "neuritogenic" effects of saposin C were evaluated in vivo using transgenic mice with prosaposin cDNAs having normal (PS-N) or mutated neuritogenic region. The mutant prosaposin cDNA (PS-CBC) encoded a chimeric saposin C that contained the non-neuritogenic sequence of saposin B, but retained acid beta-glucosidase (GCase) activation effects. When driven by the PGK (3-phosphoglycerate kinase) promoter, transgene expression was highest in the cerebrum for any of the transgenes (range from 15% to 42% of wild-type). Low levels were in visceral tissues. Prosaposin knock-out (PS-/-) mice expressing N or CBC transgenes, even at low levels, had delayed onset of neurologic signs and neuropathology, and significant lengthening of life span (from 1.7- to 7-fold) with age dependent partial correction of GlcCer and LacCer accumulation in the brain. Neuropathologic progression and neuronal glycosphingolipid storage were related directly to the transgene expression levels in the brain. Purkinje cell loss was age dependent. Gross brain and neuronal organizations were indistinguishable in PS-/- mice with or without the various transgenes, albeit the phenotype appeared later in the mice with transgenes. These studies show the degree of neuropathologic manifestations in each transgenic line depended on expression level rather than on the nature of the transgene. These studies also show in vivo localization of the GCase activation region to the carboxy terminal half of saposin C and the lack of a significant gross trophic effect of saposin C on CNS organization in vivo.
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Affiliation(s)
- Ying Sun
- The Division and Program in Human Genetics, Children's Hospital Research Foundation, Cincinnati, OH 45229-3039, USA
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Qi X, Kondoh K, Yin H, Wang M, Ponce E, Sun Y, Grabowski GA. Ex vivo localization of the mouse saposin C activation region for acid beta-glucosidase. Mol Genet Metab 2002; 76:189-200. [PMID: 12126932 DOI: 10.1016/s1096-7192(02)00040-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Saposin C is a biological activator of acid beta-glucosidase (GCase), the lysosomal hydrolase with activity towards glucosylceramide (GC). In addition, saposin C possesses a functional domain that determines the in vitro and ex vivo neuritogenic effects of prosaposin, the precursor of saposins A, B, C, and D. The domains for enzymatic activation and neuritogenic function segregate in vitro, respectively, to the carboxyl- and amino-terminal halves of human and mouse saposin C. A chimeric mouse saposin C(1-8)B(8-28)C(30-80) was created to obliterate the neuritogenic region by substituting amino acids 9-29 of saposin C with amino acids 8-28 of saposin B. This saposin showed normal in vitro enzymatic activation effects toward GCase, but no neuritogenic activity. An altered prosaposin was made to contain the chimeric saposin C region. Expression of this altered or wild-type prosaposin was driven by the PGK-1 promoter as a transgene in prosaposin knock-out mice. In cultured fibroblasts from such mice, expressed saposins localized to the lysosomal compartments. Metabolic lipid labeling using L-[3-(14)C]serine showed retention or clearance of GC in prosaposin deficient or transgene reconstituted cells, respectively. In addition, sulfatide catabolism, that requires saposin B and arylsulfatase, was also normalized in prosaposin KO cells reconstituted with the transgenes. These data show that the transgenic prosaposins were expressed and processed to functional saposins in fibroblasts. These results also show that the enzymatic activation domain is located at carboxyl-terminal half of saposin C and functions only in the context of the general saposin structure.
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Affiliation(s)
- Xiaoyang Qi
- The Division of Human Genetics, Children's Hospital Research Foundation and Department of Pediatrics, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA
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Qi X, Grabowski GA. Differential membrane interactions of saposins A and C: implications for the functional specificity. J Biol Chem 2001; 276:27010-7. [PMID: 11356836 DOI: 10.1074/jbc.m101075200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Saposins are small, heat-stable glycoprotein activators of lysosomal glycosphingolipid hydrolases that derive from a single precursor, prosaposin, by proteolytic cleavage. Three of these saposins (B, C, and D) share common structural features including a lack of tryptophan, a single glycosylation sequence, the presence of three conserved disulfide bonds, and a common multiamphipathic helical bundle motif. Saposin A contains an additional glycosylation site and a single tryptophan. The oligosaccharides on saposins are not required for in vitro activation functions. Saposins A and C were produced in Escherichia coli to contain single tryptophans at various locations to serve as intrinsic fluorescence reporters, i.e. as topological probes, for interaction with phospholipid membranes. Maximum emission shifts, aqueous and solid quenching, and resonance energy transfer were quantified by fluorescence spectroscopy. Amphipathic helices at the amino- and carboxyl termini of saposins A and C were shown to insert into the lipid bilayer to about five carbon bond lengths. In comparison, the middle region of saposins A or C were either embedded in the bilayer or solvent-exposed, respectively. Conformational changes of saposin C induced by phosphatidylserine interaction suggested the reorientation of functional helical domains. Differential interaction models are proposed for the membrane-bound saposins A and C. By site-directed mutagenesis of saposin A and C, their membrane topological structures were correlated with their activation effects on acid beta-glucosidase. These findings show that proper orientation of the middle segment of saposin C to the outside of the membrane surface is critical for its specific and multivalent interaction with acid beta-glucosidase. Such membrane interactions and orientations of the saposins determine the proximity of their activation and/or binding sites to lysosomal hydrolases or lipoid substrates.
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Affiliation(s)
- X Qi
- Division of Human Genetics, Children's Hospital Research Foundation and the Department of Pediatrics, Cincinnati, Ohio 45229-3039, USA
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Lapchak PA, Araujo DM, Shackelford DA, Zivin JA. Prosaptide exacerbates ischemia-induced behavioral deficits in vivo; an effect that does not involve mitogen-activated protein kinase activation. Neuroscience 2001; 101:811-4. [PMID: 11113331 DOI: 10.1016/s0306-4522(00)00466-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Prosaposin is a 517 amino acid membrane component and secreted protein(5,7,9) that is proteolytically cleaved to generate the four small glycoproteins; saposins A, B, C and D.(9,13,19) Prosaposin's ability to promote neurite outgrowth(31) and to protect neurons from programmed cell death(28) in vitro, as well as to rescue neurons from ischemia and other damage in vivo(11,12,15,25) implied that prosaposin was neurotrophic/neuroprotectant.(1,7,24,31) The neurotrophic sequence of prosaposin was isolated to smaller peptide fragments termed prosaptides(15,31) within the amino terminal portion of saposin C.(1,6,8,10,17,20,21,28) The proposed use of synthetic prosaptides as peripherally administered neuroprotective and/or neurotrophic therapeutic agents has stemmed from their ability to cross the blood-brain barrier,(27) as well as their reported neurotrophic activity in vitro.(15,23,31) Few studies, however, have attempted to characterize these peptides, presumably due to their reported instability following peripheral administration.(27) With the recent design of a stable 11-mer retro-inverso prosaptide,(15,31) it has become feasible to investigate the pharmacological effects of a stable version of these peptides in the validated rabbit spinal cord ischemia model that has been used extensively in the development of therapeutics to treat ischemic stroke.(4,14,16,18) Our results show not only that prosaptide was not neurotrophic/neuroprotectant in vivo, but rather it worsened ischemia-induced behavioral deficits.
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Affiliation(s)
- P A Lapchak
- University of California San Diego, Department of Neuroscience, MTF 316, 9500 Gilman Drive, La Jolla CA 92093-0624, USA.
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Qi X, Grabowski GA. Molecular and cell biology of acid beta-glucosidase and prosaposin. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2001; 66:203-39. [PMID: 11051765 DOI: 10.1016/s0079-6603(00)66030-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- X Qi
- Children's Hospital Research Foundation, Cincinnati, Ohio 45229-3039, USA
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Misasi R, Sorice M, Di Marzio L, Campana WM, Molinari S, Cifone MG, Pavan A, Pontieri GM, O'Brien JS. Prosaposin treatment induces PC12 entry in the S phase of the cell cycle and prevents apoptosis: activation of ERKs and sphingosine kinase. FASEB J 2001; 15:467-74. [PMID: 11156962 DOI: 10.1096/fj.00-0217com] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We report that prosaposin treatment induced extracellular signal-regulated kinases (ERKs) and sphingosine kinase activity, increased DNA synthesis, and prevented cell apoptosis. Prosaposin treatment induced pheochromocytoma cells (PC12) to enter the S phase of the cell cycle; this effect was inhibited by the MEK inhibitor PD98059, indicating that prosaposin-induced ERK phosphorylation is required for stimulation of DNA synthesis. The prosaposin effect was also inhibited by pertussis toxin, indicating that the prosaposin receptor is a G-protein-coupled receptor. Prosaposin rescued PC12 cells from apoptosis induced by staurosporine or ceramide. Sphingosine kinase activity was increased by prosaposin treatment. We propose that this effect is a mechanism underlying the proliferative and anti-apoptotic functions of prosaposin. Prosaposin appears to be a key regulatory factor in the ceramide-S-1-P rheostat, which regulates cell fate.
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Affiliation(s)
- R Misasi
- Dipartimento di Medicina Sperimentale e Patologia, Università 'La Sapienza' Roma, Rome, Italy.
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Campana WM, Mohiuddin L, Misasi R, O'Brien JS, Calcutt NA. Prosaposin-derived peptides enhanced sprouting of sensory neurons in vitro and induced sprouting at motor endplates in vivo. J Peripher Nerv Syst 2000; 5:126-30. [PMID: 11442168 DOI: 10.1046/j.1529-8027.2000.00019.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Prosaposin exhibits neurotrophic factor properties that are localized to a 12-amino acid sequence located in the amino terminal portion of the saposin C domain. Prosaptides are peptides derived from the neurotrophic portion of prosaposin; these have been previously reported to be bioactive in neuroblastoma cell lines in vitro. We report that prosaptides were also bioactive in explants of adult primary sensory neurons by dose-dependently increasing both the number (3- to 4-fold) and elongation of these neurites by 50%. Local injection of prosaptides into the gluteus muscle of adult mice also induced sprouting at the motor endplate. Our results indicate that prosaptides are potent neuritogenic factors for both sensory and motor neurons of adult peripheral nerve.
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Affiliation(s)
- W M Campana
- Department of Neuroscience, University of California, San Diego, La Jolla, USA.
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Yan L, Otero DA, Hiraiwa M, O'Brien JS. Prosaptide D5 reverses hyperalgesia: inhibition of calcium channels through a pertussis toxin-sensitive G-protein mechanism in the rat. Neurosci Lett 2000; 278:120-2. [PMID: 10643816 DOI: 10.1016/s0304-3940(99)00902-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A retro-inverso 11-mer peptidomimetic of prosaposin, Prosaptide D5, induced neurite outgrowth in NS20Y neuroblastoma cells and enhanced [35S]GTPgammaS binding to rat synaptosomal membrane at low nanomolar concentrations similar to prosaposin. Intramuscular injection of D5 ameliorated thermal hyperalgesia in the Seltzer rat model of neuropathic pain, returning paw withdrawal latency to control levels within 3 h after treatment. The effect was sustained for at least 48 h after injection. Prosaposin and D5 inhibited K+-stimulated synaptosomal 45Ca2+ uptake similar to omega-conotoxin MVIIC, demonstrating that both effectors modulated voltage-dependent calcium channels (VDCC); inhibition was largely abolished by pretreatment with pertussis toxin before D5 treatment. The results suggest a mechanism whereby VDCC are modulated by a pertussis toxin-sensitive G-protein coupled receptor; D5 binds to this receptor and thereby ameliorates hyperalgesia in the Seltzer model of neuropathic pain.
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Affiliation(s)
- L Yan
- Department of Neurosciences, School of Medicine, Center for Molecular Genetics, University of California, San Diego, La Jolla 92093-0634, USA
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Igase K, Tanaka J, Kumon Y, Zhang B, Sadamoto Y, Maeda N, Sakaki S, Sakanaka M. An 18-mer peptide fragment of prosaposin ameliorates place navigation disability, cortical infarction, and retrograde thalamic degeneration in rats with focal cerebral ischemia. J Cereb Blood Flow Metab 1999; 19:298-306. [PMID: 10078882 DOI: 10.1097/00004647-199903000-00008] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
It was previously reported that prosaposin possesses neurotrophic activity that is ascribed to an 18-mer peptide comprising the hydrophilic sequence of the rat saposin C domain. To evaluate the effect of the 18-mer peptide on ischemic neuronal damage, the peptide was infused in the left lateral ventricle immediately after occlusion of the left middle cerebral artery (MCA) in stroke-prone spontaneously hypertensive (SP-SH) rats. The treatment ameliorated the ischemia-induced space navigation disability and cortical infarction and prevented secondary thalamic degeneration in a dose-dependent manner. In culture experiments, treatment with the 18-mer peptide attenuated free radical-induced neuronal injury at low concentrations (0.002 to 2 pg/mL), and the peptide at higher concentrations (0.2 to 20 ng/mL) protected neurons against hypoxic insult. Furthermore, a saposin C fragment comprising the 18-mer peptide bound to synaptosomal fractions of the cerebral cortex, and this binding decreased at the 1st day after MCA occlusion and recovered to the preischemic level at the 7th day after ischemia. These findings suggest that the 18-mer peptide ameliorates neuronal damage in vivo and in vitro through binding to the functional receptor, although the cDNA encoding prosaposin receptor has not been determined yet.
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Affiliation(s)
- K Igase
- Department of Anatomy, Ehime University School of Medicine, Japan
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Abstract
Prosaposin is a multifunctional protein that encodes four glycoproteins, named saposins A, B, C and D. They participate in the catabolism of glycosphingolipids in lysosomes. When secreted, intact prosaposin may function as a neuritogenic factor. Human and mouse prosaposin displayed similar temporal and spatial regulation of expression. To gain insight into the transcriptional regulation of this locus, the 5' region was characterized from the human prosaposin gene. The putative human promoter was shown to be TATA-less, i.e. it belonged to the TATA-less housekeeping gene family. The transcription initiation sites were localized to -23, -27, -31 and -83bp 5' to ATG, compared to -87 and -94bp in the mouse. In SK-N-SH neuroblastoma cells, positive regulatory elements were detected -343 to -813bp upstream of ATG. A negative regulatory region existed between -813 and -2500bp using SK-N-SH, H441 and NS20Y cells. EMSA and DNA-footprint analysis showed that Sp1 and Sp3 are involved in human prosaposin gene regulation. Compared to the mouse promoter, the human promoter is missing a Sp1 cluster within a 310-bp upstream segment, and has AP-1, Oct-1 and two RORalpha sites that are protected from DNaseI by selected nuclear extracts.
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Affiliation(s)
- Y Sun
- The Division of Human Genetics, Children's Hospital Research Foundation at Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA
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Jin P, Sun Y, Grabowski GA. Role of Sp proteins and RORalpha in transcription regulation of murine prosaposin. J Biol Chem 1998; 273:13208-16. [PMID: 9582364 DOI: 10.1074/jbc.273.21.13208] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prosaposin is the precursor of four low molecular weight sphingolipid-activating proteins (SAPs) or saposins. These four proteins function as intracellular activators of several lysosomal enzymes involved in the degradation of glycosphingolipids, and prosaposin itself has neurite outgrowth effects. Expression of prosaposin is regulated in a temporal and spatial manner with expression in specific brain neurons and visceral cell types. Here a major regulatory fragment was characterized within 310 bp 5' to the transcription start site. Using electrophoretic mobility shift assay (EMSA) and DNA footprinting, members of the Sp family (Sp1, Sp3, and Sp4), the orphan nuclear receptor (RORalpha), and an unknown transcription factor (U; TGGGGGAG) were shown to bind to this region. To evaluate the role of such transcription factor binding sites for this locus, a series of mutant constructs was generated within this region, and their function was evaluated in cultured NS20Y neuroblastoma cells. A 3' Sp1 site, a 5' Sp1/U cluster and the RORalpha binding sites were functional. The data are consistent with a model in which the factors that bind to the Sp1/U cluster and RORE site interact negatively to diminish promoter activity to a background level that is determined primarily by the 3' Sp1 site. These interactions depend on the tissue-specific repertoire of transcription factors leading to differential expression of this locus.
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Affiliation(s)
- P Jin
- Division of Human Genetics, Children's Hospital Research Foundation, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA
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