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Deng D, Liu X, Huang W, Yuan S, Liu G, Ai S, Fu Y, Xu H, Zhang X, Li S, Xu S, Bai X, Zhang Y. Osteoclasts control endochondral ossification via regulating acetyl-CoA availability. Bone Res 2024; 12:49. [PMID: 39198395 PMCID: PMC11358419 DOI: 10.1038/s41413-024-00360-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/27/2024] [Accepted: 07/21/2024] [Indexed: 09/01/2024] Open
Abstract
Osteoclast is critical in skeletal development and fracture healing, yet the impact and underlying mechanisms of their metabolic state on these processes remain unclear. Here, by using osteoclast-specific small GTPase Rheb1-knockout mice, we reveal that mitochondrial respiration, rather than glycolysis, is essential for cathepsin K (CTSK) production in osteoclasts and is regulated by Rheb1 in a mechanistic target of rapamycin complex 1 (mTORC1)-independent manner. Mechanistically, we find that Rheb1 coordinates with mitochondrial acetyl-CoA generation to fuel CTSK, and acetyl-CoA availability in osteoclasts is the central to elevating CTSK. Importantly, our findings demonstrate that the regulation of CTSK by acetyl-CoA availability is critical and may confer a risk for abnormal endochondral ossification, which may be the main cause of poor fracture healing on alcohol consumption, targeting Rheb1 could successfully against the process. These findings uncover a pivotal role of mitochondria in osteoclasts and provide a potent therapeutic opportunity in bone disorders.
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Affiliation(s)
- Daizhao Deng
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Xianming Liu
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Wenlan Huang
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Sirui Yuan
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Genming Liu
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Shanshan Ai
- Department of Physiology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Yijie Fu
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Haokun Xu
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Xinyi Zhang
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Shihai Li
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Song Xu
- Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong, China.
| | - Xiaochun Bai
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China.
| | - Yue Zhang
- Department of Cell Biology, School of Basic Medical Science, Southern Medical University, Guangzhou, 510515, Guangdong, China.
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Brown JW, Lin X, Nicolazzi GA, Nguyen T, Radyk MD, Burclaff J, Mills JC. Cathartocytosis: How Cells Jettison Unwanted Material as They Reprogram. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.11.598489. [PMID: 38915707 PMCID: PMC11195262 DOI: 10.1101/2024.06.11.598489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Injury can cause differentiated cells to undergo massive reprogramming to become proliferative to repair tissue via a cellular program called paligenosis. Gastric digestive-enzyme-secreting chief cells use paligenosis to reprogram into progenitor-like Spasmolytic-Polypeptide Expressing Metaplasia (SPEM) cells. Stage 1 of paligenosis is to downscale mature cell architecture via a process involving lysosomes. Here, we noticed that sulfated glycoproteins (which are metaplasia and cancer markers in mice and humans) were not digested during paligenosis but excreted into the gland lumen. Various genetic and pharmacological approaches showed that endoplasmic reticulum membranes and secretory granule cargo were also excreted and that the process proceeded in parallel with, but was independent lysosomal activity. 3-dimensional light and electron-microscopy demonstrated that excretion occurred via unique, complex, multi-chambered invaginations of the apical plasma membrane. As this lysosome-independent cell cleansing process does not seem to have been priorly described, we termed it "cathartocytosis". Cathartocytosis allows a cell to rapidly eject excess material (likely in times of extreme stress such as are induced by paligenosis) without waiting for autophagic and lysosomal digestion. We speculate the ejection of sulfated glycoproteins (likely mucins) would aid in downscaling and might also help bind and flush pathogens (like H pylori which causes SPEM) away from tissue.
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Hou J, Liu J, Huang Z, Wang Y, Yao H, Hu Z, Shi C, Xu J, Wang Q. Structure and function of the membrane microdomains in osteoclasts. Bone Res 2023; 11:61. [PMID: 37989999 PMCID: PMC10663511 DOI: 10.1038/s41413-023-00294-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 09/07/2023] [Accepted: 09/18/2023] [Indexed: 11/23/2023] Open
Abstract
The cell membrane structure is closely related to the occurrence and progression of many metabolic bone diseases observed in the clinic and is an important target to the development of therapeutic strategies for these diseases. Strong experimental evidence supports the existence of membrane microdomains in osteoclasts (OCs). However, the potential membrane microdomains and the crucial mechanisms underlying their roles in OCs have not been fully characterized. Membrane microdomain components, such as scaffolding proteins and the actin cytoskeleton, as well as the roles of individual membrane proteins, need to be elucidated. In this review, we discuss the compositions and critical functions of membrane microdomains that determine the biological behavior of OCs through the three main stages of the OC life cycle.
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Affiliation(s)
- Jialong Hou
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jian Liu
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhixian Huang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yining Wang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Hanbing Yao
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhenxin Hu
- Department of Spine Surgery, Peking University Fourth School of Clinical Medicine, Beijing, China
| | - Chengge Shi
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jiake Xu
- School of Biomedical Sciences, The University of Western Australia, Perth, WA, Australia.
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
| | - Qingqing Wang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.
- Department of Orthopaedics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
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4
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Tokuda K, Lu SL, Zhang Z, Kato Y, Chen S, Noda K, Hirose K, Usami Y, Uzawa N, Murakami S, Toyosawa S, Fukuda M, Sun-Wada GH, Wada Y, Noda T. Rab32 and Rab38 maintain bone homeostasis by regulating intracellular traffic in osteoclasts. Cell Struct Funct 2023; 48:223-239. [PMID: 37793839 DOI: 10.1247/csf.23061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023] Open
Abstract
Osteoclasts play a crucial role in bone homeostasis by forming resorption pits on bone surfaces, resulting in bone resorption. The osteoclast expression of Rab38 protein is highly induced during differentiation from macrophages. Here we generated mice with double knockout (DKO) of Rab38 and its paralogue, Rab32, to investigate the roles of these proteins in osteoclasts. Bone marrow-derived macrophages from Rab32/38 DKO mice differentiated normally into osteoclasts in vitro. However, DKO osteoclasts showed reduced bone resorption activity. These osteoclasts also demonstrated defective secretion of tartrate-resistant acid phosphatase and cathepsin K into culture medium. Furthermore, the plasma membrane localization of a3, an osteoclast-specific a subunit of V-ATPase, was abrogated in DKO mice, substantiating the reduced resorption activity. In vivo, Rab32- and Rab38-positive cells were attached to the bone surface. Eight-week-old DKO mice showed significantly thickened trabecular bones in micro-CT and histomorphometry analysis, as well as reduced serum levels of cross-linked C-telopeptide of type I collagen, indicating diminished bone resorption in vivo. In DKO male mice over 10 weeks of age, hyperostosis appeared at the talofibular syndesmosis, the distal junction of the tibia and fibula. Furthermore, middle-aged mice (10 to 12 months of age) exhibited kyphosis, which is not usually observed in wild-type male mice until around 24 months of age. These results indicate that Rab32 and Rab38 contribute to osteoclast function by supporting intracellular traffic, thereby maintaining normal bone homeostasis.Key words: Rab32, Rab38, osteoclast, lysosome-related organelle, secretory lysosome.
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Affiliation(s)
- Kanako Tokuda
- Graduate School of Frontier Biosciences, Osaka University
| | - Shiou-Ling Lu
- Department of Oral Cellular Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University
| | - Zidi Zhang
- Department of Oral Cellular Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University
| | - Yumiko Kato
- Department of Oral Cellular Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University
- Department of Oral & Maxillofacial Oncology and Surgery, Graduate School of Dentistry, Osaka University
| | - Siyu Chen
- Department of Oral Cellular Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University
| | - Kazuya Noda
- Department of Oral Cellular Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University
- Department of Periodontology and Regenerative Dentistry, Graduate School of Dentistry, Osaka University
| | - Katsutoshi Hirose
- Department of Oral and Maxillofacial Pathology, Graduate School of Dentistry, Osaka University
| | - Yu Usami
- Department of Oral and Maxillofacial Pathology, Graduate School of Dentistry, Osaka University
| | - Narikazu Uzawa
- Department of Oral & Maxillofacial Oncology and Surgery, Graduate School of Dentistry, Osaka University
| | - Shinya Murakami
- Department of Periodontology and Regenerative Dentistry, Graduate School of Dentistry, Osaka University
| | - Satoru Toyosawa
- Department of Oral and Maxillofacial Pathology, Graduate School of Dentistry, Osaka University
| | - Mitsunori Fukuda
- Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University
| | - Ge-Hong Sun-Wada
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College
| | - Yoh Wada
- Department of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University
- Center for Infectious Disease Education and Research, Osaka University
| | - Takeshi Noda
- Graduate School of Frontier Biosciences, Osaka University
- Department of Oral Cellular Biology, Center for Frontier Oral Science, Graduate School of Dentistry, Osaka University
- Center for Infectious Disease Education and Research, Osaka University
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5
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Sugar transporter Slc37a2 regulates bone metabolism in mice via a tubular lysosomal network in osteoclasts. Nat Commun 2023; 14:906. [PMID: 36810735 PMCID: PMC9945426 DOI: 10.1038/s41467-023-36484-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 02/01/2023] [Indexed: 02/23/2023] Open
Abstract
Osteoclasts are giant bone-digesting cells that harbor specialized lysosome-related organelles termed secretory lysosomes (SLs). SLs store cathepsin K and serve as a membrane precursor to the ruffled border, the osteoclast's 'resorptive apparatus'. Yet, the molecular composition and spatiotemporal organization of SLs remains incompletely understood. Here, using organelle-resolution proteomics, we identify member a2 of the solute carrier 37 family (Slc37a2) as a SL sugar transporter. We demonstrate in mice that Slc37a2 localizes to the SL limiting membrane and that these organelles adopt a hitherto unnoticed but dynamic tubular network in living osteoclasts that is required for bone digestion. Accordingly, mice lacking Slc37a2 accrue high bone mass owing to uncoupled bone metabolism and disturbances in SL export of monosaccharide sugars, a prerequisite for SL delivery to the bone-lining osteoclast plasma membrane. Thus, Slc37a2 is a physiological component of the osteoclast's unique secretory organelle and a potential therapeutic target for metabolic bone diseases.
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Nε-Carboxymethyl-Lysine Mediates Vascular Calcification in Diabetes Caused by Impaired Osteoclastic Resorption Activity Through NFATc1-GNPTAB. J Cardiovasc Transl Res 2023; 16:233-243. [PMID: 35972719 DOI: 10.1007/s12265-022-10300-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/29/2022] [Indexed: 10/15/2022]
Abstract
Nε-carboxymethyl-lysine (CML) is closely associated with vascular calcification in diabetes. Osteoclasts are the only cells with bone resorption activity that have the potential to reverse calcification. This study aimed to investigate the mechanism of CML in the bone resorption activity of macrophage-derived osteoclasts in diabetic calcified plaques. Macrophage-derived osteoclasts were found to be present in calcified plaques of the anterior tibial artery in patients with diabetic amputation. Furthermore, in vitro studies showed that CML induced the differentiation of macrophages into osteoclasts, although, the bone resorption activity of these macrophage-derived osteoclasts was impaired. CML significantly increased the levels of NFATc1and GNPTAB. In vivo studies showed that there was more calcium deposition and less TRAP was less in the CML group while this effect was reversed after silencing of NFATc1. In conclusion, CML mediates NFATc1-GNPTAB to regulate bone resorption activity of osteoclasts in diabetic calcified plaques. CML promotes macrophage differentiation into osteoclasts, but their function is impaired in diabetic calcified plaques through NFATc1-GNPTAB, which eventually leads to the further progression of vascular calcification in diabetes.
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Majumder P, Edmison D, Rodger C, Patel S, Reid E, Gowrishankar S. AP-4 regulates neuronal lysosome composition, function, and transport via regulating export of critical lysosome receptor proteins at the trans-Golgi network. Mol Biol Cell 2022; 33:ar102. [PMID: 35976706 PMCID: PMC9635302 DOI: 10.1091/mbc.e21-09-0473] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The adaptor protein complex-4 or AP-4 is known to mediate autophagosome maturation through regulating sorting of transmembrane cargo such as ATG9A at the Golgi. There is a need to understand AP-4 function in neurons, as mutations in any of its four subunits cause a complex form of hereditary spastic paraplegia (HSP) with intellectual disability. While AP-4 has been implicated in regulating trafficking and distribution of cargo such as ATG9A and APP, little is known about its effect on neuronal lysosomal protein traffic, lysosome biogenesis and function. In this study, we demonstrate that in human iPSC-derived neurons AP-4 regulates lysosome composition, function and transport via regulating export of critical lysosomal receptors, including Sortilin 1, from the trans-Golgi network to endo-lysosomes. Additionally, loss of AP-4 causes endo-lysosomes to stall and build up in axonal swellings potentially through reduced recruitment of retrograde transport machinery to the organelle. These findings of axonal lysosome build-up are highly reminiscent of those observed in Alzheimer's disease as well as in neurons modelling the most common form of HSP, caused by spastin mutations. Our findings implicate AP-4 as a critical regulator of neuronal lysosome biogenesis and altered lysosome function and axonal endo-lysosome transport as an underlying defect in AP-4 deficient HSP. Additionally, our results also demonstrate the utility of the human i3Neuronal model system in investigating neuronal phenotypes observed in AP-4 deficient mice and/or the human AP-4 deficiency syndrome. [Media: see text] [Media: see text].
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Affiliation(s)
- Piyali Majumder
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Daisy Edmison
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Catherine Rodger
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK
| | - Sruchi Patel
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Evan Reid
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, England, UK
| | - Swetha Gowrishankar
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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8
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Anderson J, Walker G, Pu J. BORC-ARL8-HOPS ensemble is required for lysosomal cholesterol egress through NPC2. Mol Biol Cell 2022; 33:ar81. [PMID: 35653304 PMCID: PMC9582633 DOI: 10.1091/mbc.e21-11-0595-t] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 05/16/2022] [Accepted: 05/24/2022] [Indexed: 11/11/2022] Open
Abstract
Lysosomes receive extracellular and intracellular cholesterol and redistribute it throughout the cell. Cholesterol egress from lysosomes is critical for cholesterol homeostasis, and its failure underlies the pathogenesis of genetic disorders such as Niemann-Pick C (NPC) disease. Here we report that the BLOC one-related complex (BORC)-ARL8-homotypic fusion and protein sorting (HOPS) ensemble is required for egress of free cholesterol from lysosomes and for storage of esterified cholesterol in lipid droplets. Depletion of BORC, ARL8, or HOPS does not alter the localization of the lysosomal transmembrane cholesterol transporter NPC1 to degradative compartments but decreases the association of the luminal transporter NPC2 and increases NPC2 secretion. BORC-ARL8-HOPS depletion also increases lysosomal degradation of cation-independent (CI)-mannose 6-phosphate (M6P) receptor (MPR), which normally sorts NPC2 to the endosomal-lysosomal system and then is recycled to the trans-Golgi network. These defects likely result from impaired HOPS-dependent fusion of endosomal-lysosomal organelles and an uncharacterized function of HOPS in CI-MPR recycling. Our study demonstrates that the BORC-ARL8-HOPS ensemble is required for cholesterol egress from lysosomes by enabling CI-MPR-dependent trafficking of NPC2 to the endosomal-lysosomal system.
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Affiliation(s)
- Jacob Anderson
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131
- Autophagy, Inflammation, and Metabolism Center of Biomedical Research Excellence, University of New Mexico, Albuquerque, NM 87131
| | - Gerard Walker
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Jing Pu
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131
- Autophagy, Inflammation, and Metabolism Center of Biomedical Research Excellence, University of New Mexico, Albuquerque, NM 87131
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9
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Mucolipidoses Overview: Past, Present, and Future. Int J Mol Sci 2020; 21:ijms21186812. [PMID: 32957425 PMCID: PMC7555117 DOI: 10.3390/ijms21186812] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 12/12/2022] Open
Abstract
Mucolipidosis II and III (ML II/III) are caused by a deficiency of uridine-diphosphate N-acetylglucosamine: lysosomal-enzyme-N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase, EC2.7.8.17), which tags lysosomal enzymes with a mannose 6-phosphate (M6P) marker for transport to the lysosome. The process is performed by a sequential two-step process: first, GlcNAc-1-phosphotransferase catalyzes the transfer of GlcNAc-1-phosphate to the selected mannose residues on lysosomal enzymes in the cis-Golgi network. The second step removes GlcNAc from lysosomal enzymes by N-acetylglucosamine-1-phosphodiester α-N-acetylglucosaminidase (uncovering enzyme) and exposes the mannose 6-phosphate (M6P) residues in the trans-Golgi network, in which the enzymes are targeted to the lysosomes by M6Preceptors. A deficiency of GlcNAc-1-phosphotransferase causes the hypersecretion of lysosomal enzymes out of cells, resulting in a shortage of multiple lysosomal enzymes within lysosomes. Due to a lack of GlcNAc-1-phosphotransferase, the accumulation of cholesterol, phospholipids, glycosaminoglycans (GAGs), and other undegraded substrates occurs in the lysosomes. Clinically, ML II and ML III exhibit quite similar manifestations to mucopolysaccharidoses (MPSs), including specific skeletal deformities known as dysostosis multiplex and gingival hyperplasia. The life expectancy is less than 10 years in the severe type, and there is no definitive treatment for this disease. In this review, we have described the updated diagnosis and therapy on ML II/III.
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Yu J, Adapala NS, Doherty L, Sanjay A. Cbl-PI3K interaction regulates Cathepsin K secretion in osteoclasts. Bone 2019; 127:376-385. [PMID: 31299383 PMCID: PMC6708784 DOI: 10.1016/j.bone.2019.07.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/06/2019] [Accepted: 07/08/2019] [Indexed: 10/26/2022]
Abstract
Effective bone resorption by osteoclasts is critical for balanced bone remodeling. We have previously reported that mice harboring a substitution mutation of tyrosine 737 to phenylalanine in the adapter protein Cbl (CblY737F, YF) have increased bone volume partly due to decreased osteoclast-mediated bone resorption. The CblY737F mutation abrogates interaction between Cbl and the p85 subunit of PI3K. Here, we studied the mechanism for defective resorptive function of YF mutant osteoclasts. The YF osteoclasts had intact actin cytoskeletons and sealing zones. Expression and localization of proteins needed for acidification of the resorptive lacunae were also comparable between the WT and YF osteoclasts. In contrast, secretion of Cathepsin K, a major protease needed to degrade collagen, was diminished in the conditioned media derived from YF osteoclasts. The targeting of Cathepsin K into LAMP2-positive vesicles was also compromised due to decreased number of LAMP2-positive vesicles in YF osteoclasts. Further, we found that in contrast to WT, conditioned media derived from YF osteoclasts promoted increased numbers of alkaline phosphatase positive colonies, and increased expression of osteogenic markers in WT calvarial cultures. Cumulatively, our results suggest that the Cbl-PI3K interaction regulates Cathepsin K secretion required for proper bone resorption, and secretion of factors which promote osteogenesis.
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Affiliation(s)
- Jungeun Yu
- Department of Orthopaedic Surgery, UConn Health, Farmington, CT 06030, United States of America
| | - Naga Suresh Adapala
- Department of Orthopaedic Surgery, UConn Health, Farmington, CT 06030, United States of America
| | - Laura Doherty
- Department of Orthopaedic Surgery, UConn Health, Farmington, CT 06030, United States of America
| | - Archana Sanjay
- Department of Orthopaedic Surgery, UConn Health, Farmington, CT 06030, United States of America.
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11
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Raynaud-Messina B, Verollet C, Maridonneau-Parini I. The osteoclast, a target cell for microorganisms. Bone 2019; 127:315-323. [PMID: 31233933 DOI: 10.1016/j.bone.2019.06.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/11/2019] [Accepted: 06/21/2019] [Indexed: 02/02/2023]
Abstract
Bone is a highly adaptive tissue with regenerative properties that is subject to numerous diseases. Infection is one of the causes of altered bone homeostasis. Bone infection happens subsequently to bone surgery or to systemic spreading of microorganisms. In addition to osteoblasts, osteoclasts (OCs) also constitute cell targets for pathogens. OCs are multinucleated cells that have the exclusive ability to resorb bone mineral tissue. However, the OC is much more than a bone eater. Beyond its role in the control of bone turnover, the OC is an immune cell that produces and senses inflammatory cytokines, ingests microorganisms and presents antigens. Today, increasing evidence shows that several pathogens use OC as a host cell to grow, generating debilitating bone defects. In this review, we exhaustively inventory the bacteria and viruses that infect OC and report the present knowledge in this topic. We point out that most of the microorganisms enhance the bone resorption activity of OC. We notice that pathogen interactions with the OC require further investigation, in particular to validate the OC as a host cell in vivo and to identify the cellular mechanisms involved in altered bone resorption. Thus, we conclude that the OC is a new cell target for pathogens; this new research area paves the way for new therapeutic strategies in the infections causing bone defects.
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Affiliation(s)
- Brigitte Raynaud-Messina
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France; International Associated Laboratory (LIA) CNRS "IM-TB/HIV" (1167), Toulouse, France; International Associated Laboratory (LIA) CNRS "IM-TB/HIV" (1167), Buenos Aires, Argentina
| | - Christel Verollet
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France; International Associated Laboratory (LIA) CNRS "IM-TB/HIV" (1167), Toulouse, France; International Associated Laboratory (LIA) CNRS "IM-TB/HIV" (1167), Buenos Aires, Argentina
| | - Isabelle Maridonneau-Parini
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France; International Associated Laboratory (LIA) CNRS "IM-TB/HIV" (1167), Toulouse, France; International Associated Laboratory (LIA) CNRS "IM-TB/HIV" (1167), Buenos Aires, Argentina.
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12
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New Insights into the Roles of Monocytes/Macrophages in Cardiovascular Calcification Associated with Chronic Kidney Disease. Toxins (Basel) 2019; 11:toxins11090529. [PMID: 31547340 PMCID: PMC6784181 DOI: 10.3390/toxins11090529] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/06/2019] [Accepted: 09/09/2019] [Indexed: 12/13/2022] Open
Abstract
Cardiovascular disease (CVD) is an important cause of death in patients with chronic kidney disease (CKD), and cardiovascular calcification (CVC) is one of the strongest predictors of CVD in this population. Cardiovascular calcification results from complex cellular interactions involving the endothelium, vascular/valvular cells (i.e., vascular smooth muscle cells, valvular interstitial cells and resident fibroblasts), and monocyte-derived macrophages. Indeed, the production of pro-inflammatory cytokines and oxidative stress by monocyte-derived macrophages is responsible for the osteogenic transformation and mineralization of vascular/valvular cells. However, monocytes/macrophages show the ability to modify their phenotype, and consequently their functions, when facing environmental modifications. This plasticity complicates efforts to understand the pathogenesis of CVC-particularly in a CKD setting, where both uraemic toxins and CKD treatment may affect monocyte/macrophage functions and thereby influence CVC. Here, we review (i) the mechanisms by which each monocyte/macrophage subset either promotes or prevents CVC, and (ii) how both uraemic toxins and CKD therapies might affect these monocyte/macrophage functions.
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13
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Membrane trafficking in osteoclasts and implications for osteoporosis. Biochem Soc Trans 2019; 47:639-650. [PMID: 30837319 PMCID: PMC6490703 DOI: 10.1042/bst20180445] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/03/2019] [Accepted: 02/05/2019] [Indexed: 12/20/2022]
Abstract
Osteoclasts are large multinucleated cells exquisitely adapted to resorb bone matrix. Like other eukaryotes, osteoclasts possess an elaborate ensemble of intracellular organelles through which solutes, proteins and other macromolecules are trafficked to their target destinations via membrane-bound intermediaries. During bone resorption, membrane trafficking must be tightly regulated to sustain the structural and functional polarity of the osteoclasts’ membrane domains. Of these, the ruffled border (RB) is most characteristic, functioning as the osteoclasts' secretory apparatus. This highly convoluted organelle is classically considered to be formed by the targeted fusion of acidic vesicles with the bone-facing plasma membrane. Emerging findings disclose new evidence that the RB is far more complex than previously envisaged, possessing discrete subdomains that are serviced by several intersecting endocytic, secretory, transcytotic and autophagic pathways. Bone-resorbing osteoclasts therefore serve as a unique model system for studying polarized membrane trafficking. Recent advances in high-resolution microscopy together with the convergence of genetic and cell biological studies in humans and in mice have helped illuminate the major membrane trafficking pathways in osteoclasts and unmask the core molecular machinery that governs these distinct vesicle transport routes. Among these, small Rab GTPases, their binding partners and members of the endocytic sorting nexin family have emerged as critical regulators. This mini review summarizes our current understanding of membrane trafficking in osteoclasts, the key molecular participants, and discusses how these transport machinery may be exploited for the development of new therapies for metabolic disorders of bone-like osteoporosis.
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14
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Pohl S, Angermann A, Jeschke A, Hendrickx G, Yorgan TA, Makrypidi-Fraune G, Steigert A, Kuehn SC, Rolvien T, Schweizer M, Koehne T, Neven M, Winter O, Velho RV, Albers J, Streichert T, Pestka JM, Baldauf C, Breyer S, Stuecker R, Muschol N, Cox TM, Saftig P, Paganini C, Rossi A, Amling M, Braulke T, Schinke T. The Lysosomal Protein Arylsulfatase B Is a Key Enzyme Involved in Skeletal Turnover. J Bone Miner Res 2018; 33:2186-2201. [PMID: 30075049 DOI: 10.1002/jbmr.3563] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/10/2018] [Accepted: 06/20/2018] [Indexed: 12/24/2022]
Abstract
Skeletal pathologies are frequently observed in lysosomal storage disorders, yet the relevance of specific lysosomal enzymes in bone remodeling cell types is poorly defined. Two lysosomal enzymes, ie, cathepsin K (Ctsk) and Acp5 (also known as tartrate-resistant acid phosphatase), have long been known as molecular marker proteins of differentiated osteoclasts. However, whereas the cysteine protease Ctsk is directly involved in the degradation of bone matrix proteins, the molecular function of Acp5 in osteoclasts is still unknown. Here we show that Acp5, in concert with Acp2 (lysosomal acid phosphatase), is required for dephosphorylation of the lysosomal mannose 6-phosphate targeting signal to promote the activity of specific lysosomal enzymes. Using an unbiased approach we identified the glycosaminoglycan-degrading enzyme arylsulfatase B (Arsb), mutated in mucopolysaccharidosis type VI (MPS-VI), as an osteoclast marker, whose activity depends on dephosphorylation by Acp2 and Acp5. Similar to Acp2/Acp5-/- mice, Arsb-deficient mice display lysosomal storage accumulation in osteoclasts, impaired osteoclast activity, and high trabecular bone mass. Of note, the most prominent lysosomal storage accumulation was observed in osteocytes from Arsb-deficient mice, yet this pathology did not impair production of sclerostin (Sost) and Fgf23. Because the influence of enzyme replacement therapy (ERT) on bone remodeling in MPS-VI is still unknown, we additionally treated Arsb-deficient mice by weekly injection of recombinant human ARSB from 12 to 24 weeks of age. We found that the high bone mass phenotype of Arsb-deficient mice and the underlying bone cell deficits were fully corrected by ERT in the trabecular compartment. Taken together, our results do not only show that the function of Acp5 in osteoclasts is linked to dephosphorylation and activation of lysosomal enzymes, they also provide an important proof-of-principle for the feasibility of ERT to correct bone cell pathologies in lysosomal storage disorders. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.
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Affiliation(s)
- Sandra Pohl
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Alexandra Angermann
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anke Jeschke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gretl Hendrickx
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Timur A Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Georgia Makrypidi-Fraune
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anita Steigert
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sonja C Kuehn
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tim Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michaela Schweizer
- Department of Electron Microscopy, Center of Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Till Koehne
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Orthodontics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mona Neven
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Olga Winter
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Renata Voltolini Velho
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Joachim Albers
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Streichert
- Department of Clinical Chemistry, University Hospital Cologne, Cologne, Germany
| | - Jan M Pestka
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christina Baldauf
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra Breyer
- Department of Orthopedics, Children's Hospital Hamburg-Altona, Hamburg, Germany
| | - Ralf Stuecker
- Department of Orthopedics, Children's Hospital Hamburg-Altona, Hamburg, Germany
| | - Nicole Muschol
- Department of Electron Microscopy, Center of Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Timothy M Cox
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Paul Saftig
- Institute of Biochemistry, Christian-Albrechts-University, Kiel, Germany
| | - Chiara Paganini
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Antonio Rossi
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Braulke
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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15
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Segeletz S, Danglot L, Galli T, Hoflack B. ARAP1 Bridges Actin Dynamics and AP-3-Dependent Membrane Traffic in Bone-Digesting Osteoclasts. iScience 2018; 6:199-211. [PMID: 30240610 PMCID: PMC6137390 DOI: 10.1016/j.isci.2018.07.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 06/06/2018] [Accepted: 07/20/2018] [Indexed: 12/23/2022] Open
Abstract
Bone-resorbing osteoclasts play a central role in bone remodeling and its pathology. To digest bone, osteoclasts re-organize both F-actin, to assemble podosomes/sealing zones, and membrane traffic, to form bone-facing ruffled borders enriched in lysosomal membrane proteins. It remains elusive how these processes are coordinated. Here, we show that ARAP1 (ArfGAP with RhoGAP domain, ankyrin repeat and PH domain-containing protein 1) fulfills this function. At podosomes/sealing zones, ARAP1 is part of a protein complex where its RhoGAP domain regulates actin dynamics. At endosomes, ARAP1 interacts with AP-3 adaptor complexes where its Arf-GAP domain regulates the Arf1-dependent AP-3 binding to membranes and, consequently lysosomal membrane protein transport to ruffled borders. Accordingly, ARAP1 or AP-3 depletion in osteoclasts alters their capacity to digest bone in vitro. and AP-3δ-deficient mocha mice, a model of the Hermansky-Pudlak storage pool syndrome, develop osteoporosis. Thus, ARAP1 bridges F-actin and membrane dynamics in osteoclasts for proper bone homeostasis. ARAP1 is a bridging factor controlling actin and membrane dynamics in osteoclasts ARAP1 controls podosome dynamics and AP-3 coat recruitment to membranes AP-3 controls targeting of lysosomal membrane proteins to the ruffled border AP-3-deficient mocha mice develop osteoporosis
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Affiliation(s)
- Sandra Segeletz
- Biotechnology Center, Technische Universität Dresden, Tatzberg 47-51, Dresden 01307, Germany
| | - Lydia Danglot
- Centre de Psychiatrie et Neurosciences, UMR-S894 INSERM, Université Paris Descartes, 102-108 rue de la Santé, Paris 75014, France
| | - Thierry Galli
- Centre de Psychiatrie et Neurosciences, UMR-S894 INSERM, Université Paris Descartes, 102-108 rue de la Santé, Paris 75014, France
| | - Bernard Hoflack
- Biotechnology Center, Technische Universität Dresden, Tatzberg 47-51, Dresden 01307, Germany.
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16
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Matsumoto N, Sekiya M, Tohyama K, Ishiyama-Matsuura E, Sun-Wada GH, Wada Y, Futai M, Nakanishi-Matsui M. Essential Role of the a3 Isoform of V-ATPase in Secretory Lysosome Trafficking via Rab7 Recruitment. Sci Rep 2018; 8:6701. [PMID: 29712939 PMCID: PMC5928161 DOI: 10.1038/s41598-018-24918-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 04/09/2018] [Indexed: 12/12/2022] Open
Abstract
Secretory lysosomes are required for the specialised functions of various types of differentiated cells. In osteoclasts, the lysosomal proton pump V-ATPase (vacuolar-type ATPase) is targeted to the plasma membrane via secretory lysosomes and subsequently acidifies the extracellular compartment, providing optimal conditions for bone resorption. However, little is known about the mechanism underlying this trafficking of secretory lysosomes. Here, we demonstrate that the lysosome-specific a3 isoform of the V-ATPase a subunit plays an indispensable role in secretory lysosome trafficking, together with Rab7, a small GTPase involved in organelle trafficking. In osteoclasts lacking a3, lysosomes were not transported to the cell periphery, and Rab7 was not localised to lysosomes but diffused throughout the cytoplasm. Expression of dominant-negative (GDP-bound form) Rab7 inhibited lysosome trafficking in wild-type cells. Furthermore, a3 directly interacted with the GDP-bound forms of Rab7 and Rab27A. These findings reveal a novel role for the proton pump V-ATPase in secretory lysosome trafficking and an unexpected mechanistic link with Rab GTPases.
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Affiliation(s)
- Naomi Matsumoto
- Division of Biochemistry, School of Pharmacy, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan
| | - Mizuki Sekiya
- Division of Biochemistry, School of Pharmacy, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan
| | - Koujiro Tohyama
- The Center for Electron Microscopy and Bio-Imaging Research, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan.,Department of Physiology, School of Dentistry, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan
| | - Eri Ishiyama-Matsuura
- The Center for Electron Microscopy and Bio-Imaging Research, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan
| | - Ge-Hong Sun-Wada
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Doshisha Women's College, Kyotanabe, Kyoto, 610-0395, Japan
| | - Yoh Wada
- Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan
| | - Masamitsu Futai
- Division of Biochemistry, School of Pharmacy, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan
| | - Mayumi Nakanishi-Matsui
- Division of Biochemistry, School of Pharmacy, Iwate Medical University, Yahaba, Iwate, 028-3694, Japan.
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17
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Tsukuba T, Sakai E, Nishishita K, Kadowaki T, Okamoto K. New functions of lysosomes in bone cells. J Oral Biosci 2017. [DOI: 10.1016/j.job.2017.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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18
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Subcellular Trafficking of Mammalian Lysosomal Proteins: An Extended View. Int J Mol Sci 2016; 18:ijms18010047. [PMID: 28036022 PMCID: PMC5297682 DOI: 10.3390/ijms18010047] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 12/15/2016] [Accepted: 12/18/2016] [Indexed: 01/02/2023] Open
Abstract
Lysosomes clear macromolecules, maintain nutrient and cholesterol homeostasis, participate in tissue repair, and in many other cellular functions. To assume these tasks, lysosomes rely on their large arsenal of acid hydrolases, transmembrane proteins and membrane-associated proteins. It is therefore imperative that, post-synthesis, these proteins are specifically recognized as lysosomal components and are correctly sorted to this organelle through the endosomes. Lysosomal transmembrane proteins contain consensus motifs in their cytosolic regions (tyrosine- or dileucine-based) that serve as sorting signals to the endosomes, whereas most lysosomal acid hydrolases acquire mannose 6-phosphate (Man-6-P) moieties that mediate binding to two membrane receptors with endosomal sorting motifs in their cytosolic tails. These tyrosine- and dileucine-based motifs are tickets for boarding in clathrin-coated carriers that transport their cargo from the trans-Golgi network and plasma membrane to the endosomes. However, increasing evidence points to additional mechanisms participating in the biogenesis of lysosomes. In some cell types, for example, there are alternatives to the Man-6-P receptors for the transport of some acid hydrolases. In addition, several “non-consensus” sorting motifs have been identified, and atypical transport routes to endolysosomes have been brought to light. These “unconventional” or “less known” transport mechanisms are the focus of this review.
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19
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Fujiwara T, Ye S, Castro-Gomes T, Winchell CG, Andrews NW, Voth DE, Varughese KI, Mackintosh SG, Feng Y, Pavlos N, Nakamura T, Manolagas SC, Zhao H. PLEKHM1/DEF8/RAB7 complex regulates lysosome positioning and bone homeostasis. JCI Insight 2016; 1:e86330. [PMID: 27777970 DOI: 10.1172/jci.insight.86330] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Mutations of the Plekhm1 gene in humans and rats cause osteopetrosis, an inherited bone disease characterized by diminished bone resorption by osteoclasts. PLEKHM1 binds to RAB7 and is critical for lysosome trafficking. However, the molecular mechanisms by which PLEKHM1 regulates lysosomal pathways remain unknown. Here, we generated germline and conditional Plekhm1-deficient mice. These mice displayed no overt abnormalities in major organs, except for an increase in trabecular bone mass. Furthermore, loss of PLEKHM1 abrogated the peripheral distribution of lysosomes and bone resorption in osteoclasts. Mechanistically, we indicated that DEF8 interacts with PLEKHM1 and promotes its binding to RAB7, whereas the binding of FAM98A and NDEL1 with PLEKHM1 connects lysosomes to microtubules. Importantly, suppression of these proteins results in lysosome positioning and bone resorption defects similar to those of Plekhm1-null osteoclasts. Thus, PLHKEM1, DEF8, FAM98A, and NDEL1 constitute a molecular complex that regulates lysosome positioning and secretion through RAB7.
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Affiliation(s)
- Toshifumi Fujiwara
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Shiqiao Ye
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Thiago Castro-Gomes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | | | - Norma W Andrews
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | | | | | - Samuel G Mackintosh
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Yunfeng Feng
- Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA
| | - Nathan Pavlos
- Center for Orthopedic Research, Dentistry and Health Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Takashi Nakamura
- Department of Biochemistry & Integrative Medical Biology, School of Medicine, Keio University, Tokyo, Japan
| | - Stavros C Manolagas
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Haibo Zhao
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.,Department of Physiology and Biophysics, and
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20
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Puissant E, Boonen M. Monocytes/Macrophages Upregulate the Hyaluronidase HYAL1 and Adapt Its Subcellular Trafficking to Promote Extracellular Residency upon Differentiation into Osteoclasts. PLoS One 2016; 11:e0165004. [PMID: 27755597 PMCID: PMC5068775 DOI: 10.1371/journal.pone.0165004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/04/2016] [Indexed: 11/18/2022] Open
Abstract
Osteoclasts are giant bone-resorbing cells originating from monocytes/macrophages. During their differentiation, they overexpress two lysosomal enzymes, cathepsin K and TRAP, which are secreted into the resorption lacuna, an acidified sealed area in contact with bone matrix where bone degradation takes place. Here we report that the acid hydrolase HYAL1, a hyaluronidase able to degrade the glycosaminoglycans hyaluronic acid (HA) and chondroitin sulfate, is also upregulated upon osteoclastogenesis. The mRNA expression and protein level of HYAL1 are markedly increased in osteoclasts differentiated from RAW264.7 mouse macrophages or primary mouse bone marrow monocytes compared to these precursor cells. As a result, the HYAL1-mediated HA hydrolysis ability of osteoclasts is strongly enhanced. Using subcellular fractionation, we demonstrate that HYAL1 proteins are sorted to the osteoclast lysosomes even though, in contrast to cathepsin K and TRAP, HYAL1 is poorly mannose 6-phosphorylated. We reported previously that macrophages secrete HYAL1 proforms by constitutive secretion, and that these are recaptured by the cell surface mannose receptor, processed in endosomes and sorted to lysosomes. Present work highlights that osteoclasts secrete HYAL1 in two ways, through lysosomal exocytosis and constitutive secretion, and that these cells promote the extracellular residency of HYAL1 through downregulation of the mannose receptor. Interestingly, the expression of the other main hyaluronidase, HYAL2, and of lysosomal exoglycosidases involved in HA degradation, does not increase similarly to HYAL1 upon osteoclastogenesis. Taken together, these findings point out the predominant involvement of HYAL1 in bone HA metabolism and perhaps bone remodeling via the resorption lacuna.
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Affiliation(s)
- Emeline Puissant
- Laboratoire de Chimie Physiologique - URPhyM, University of Namur, Namur, Belgium
| | - Marielle Boonen
- Laboratoire de Chimie Physiologique - URPhyM, University of Namur, Namur, Belgium
- * E-mail:
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21
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Flanagan-Steet H, Aarnio M, Kwan B, Guihard P, Petrey A, Haskins M, Blanchard F, Steet R. Cathepsin-Mediated Alterations in TGFß-Related Signaling Underlie Disrupted Cartilage and Bone Maturation Associated With Impaired Lysosomal Targeting. J Bone Miner Res 2016; 31:535-48. [PMID: 26404503 PMCID: PMC4808492 DOI: 10.1002/jbmr.2722] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 11/11/2022]
Abstract
Hypersecretion of acid hydrolases is a hallmark feature of mucolipidosis II (MLII), a lysosomal storage disease caused by loss of carbohydrate-dependent lysosomal targeting. Inappropriate extracellular action of these hydrolases is proposed to contribute to skeletal pathogenesis, but the mechanisms that connect hydrolase activity to the onset of disease phenotypes remain poorly understood. Here we link extracellular cathepsin K activity to abnormal bone and cartilage development in MLII animals by demonstrating that it disrupts the balance of TGFß-related signaling during chondrogenesis. TGFß-like Smad2,3 signals are elevated and BMP-like Smad1,5,8 signals reduced in both feline and zebrafish MLII chondrocytes and osteoblasts, maintaining these cells in an immature state. Reducing either cathepsin K activity or expression of the transcriptional regulator Sox9a in MLII zebrafish significantly improved phenotypes. We further identify components of the large latent TGFß complex as novel targets of cathepsin K at neutral pH, providing a possible mechanism for enhanced Smad2,3 activation in vivo. These findings highlight the complexity of the skeletal disease associated with MLII and bring new insight to the role of secreted cathepsin proteases in cartilage development and growth factor regulation.
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Affiliation(s)
| | - Megan Aarnio
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Brian Kwan
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | | | - Aaron Petrey
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Mark Haskins
- Departments of Pathology and Clinical Studies, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA
| | | | - Richard Steet
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
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22
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Boonen M, Staudt C, Gilis F, Oorschot V, Klumperman J, Jadot M. Cathepsin D and its newly identified transport receptor SEZ6L2 can modulate neurite outgrowth. J Cell Sci 2015; 129:557-68. [PMID: 26698217 DOI: 10.1242/jcs.179374] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/17/2015] [Indexed: 12/14/2022] Open
Abstract
How, in the absence of a functional mannose 6-phosphate (Man-6-P)-signal-dependent transport pathway, some acid hydrolases remain sorted to endolysosomes in the brain is poorly understood. We demonstrate that cathepsin D binds to mouse SEZ6L2, a type 1 transmembrane protein predominantly expressed in the brain. Studies of the subcellular trafficking of SEZ6L2, and its silencing in a mouse neuroblastoma cell line reveal that SEZ6L2 is involved in the trafficking of cathepsin D to endosomes. Moreover, SEZ6L2 can partially correct the cathepsin D hypersecretion resulting from the knockdown of UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase in HeLa cells (i.e. in cells that are unable to synthesize Man-6-P signals). Interestingly, cleavage of SEZ6L2 by cathepsin D generates an N-terminal soluble fragment that induces neurite outgrowth, whereas its membrane counterpart prevents this. Taken together, our findings highlight that SEZ6L2 can serve as receptor to mediate the sorting of cathepsin D to endosomes, and suggest that proteolytic cleavage of SEZ6L2 by cathepsin D modulates neuronal differentiation.
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Affiliation(s)
- Marielle Boonen
- URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 rue de Bruxelles, Namur 5000, Belgium
| | - Catherine Staudt
- URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 rue de Bruxelles, Namur 5000, Belgium
| | - Florentine Gilis
- URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 rue de Bruxelles, Namur 5000, Belgium
| | - Viola Oorschot
- Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands
| | - Judith Klumperman
- Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands
| | - Michel Jadot
- URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 rue de Bruxelles, Namur 5000, Belgium
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23
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Zhang JY, Wu Y, Zhao S, Liu ZX, Zeng SM, Zhang GX. Lysosomes are involved in induction of steroidogenic acute regulatory protein (StAR) gene expression and progesterone synthesis through low-density lipoprotein in cultured bovine granulosa cells. Theriogenology 2015; 84:811-7. [DOI: 10.1016/j.theriogenology.2015.05.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 05/14/2015] [Accepted: 05/20/2015] [Indexed: 11/29/2022]
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24
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Lei Y, Iwashita M, Choi J, Aikawa M, Aikawa E. N-acetylglucosamine-1-Phosphate Transferase Suppresses Lysosomal Hydrolases in Dysfunctional Osteoclasts: A Potential Mechanism for Vascular Calcification. J Cardiovasc Dev Dis 2015; 2:31-47. [PMID: 29371511 PMCID: PMC5753093 DOI: 10.3390/jcdd2020031] [Citation(s) in RCA: 6] [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: 02/21/2015] [Revised: 03/31/2015] [Accepted: 04/07/2015] [Indexed: 01/18/2023] Open
Abstract
In addition to increased differentiation of vascular smooth muscle cells into osteoblast-like phenotypes, the limited accumulation of osteoclasts in atherosclerotic plaques or their dysfunction may participate in potential mechanisms for vascular calcification. N-acetylglucosamine-1-phosphate transferase containing alpha and beta subunits (GNPTAB) is a transmembrane enzyme complex that mediates the vesicular transport of lysosomal hydrolases. GNPTAB may also regulate the biogenesis of lysosomal hydrolases from bone-marrow derived osteoclasts. In this study, the areas surrounding calcification in human atherosclerotic plaques contained high levels of GNPTAB and low levels of lysosomal hydrolases such as cathepsin K (CTSK) and tartrate-resistant acid phosphatase (TRAP), as demonstrated by immunohistochemistry and laser-capture microdissection-assisted mRNA expression analysis. We therefore hypothesized that GNPTAB secretion may suppress the release of CTSK and TRAP by vascular osteoclast-like cells, thus causing their dysfunction and reducing the resorption of calcification. We used human primary macrophages derived from peripheral blood mononuclear cells, an established osteoclast differentiation model. GNPTAB siRNA silencing accelerated the formation of functional osteoclasts as detected by increased secretion of CTSK and TRAP and increased their bone resorption activity as gauged by resorption pits assay. We concluded that high levels of GNPTAB inhibit secretion of lysosomal hydrolases in dysfunctional osteoclasts, thereby affecting their resorption potential in cardiovascular calcification.
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Affiliation(s)
- Yang Lei
- Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Masaya Iwashita
- Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Jung Choi
- Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Masanori Aikawa
- Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Elena Aikawa
- Center for Interdisciplinary Cardiovascular Sciences, Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Osteopetrorickets due to Snx10 deficiency in mice results from both failed osteoclast activity and loss of gastric acid-dependent calcium absorption. PLoS Genet 2015; 11:e1005057. [PMID: 25811986 PMCID: PMC4374855 DOI: 10.1371/journal.pgen.1005057] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 02/07/2015] [Indexed: 12/26/2022] Open
Abstract
Mutations in sorting nexin 10 (Snx10) have recently been found to account for roughly 4% of all human malignant osteopetrosis, some of them fatal. To study the disease pathogenesis, we investigated the expression of Snx10 and created mouse models in which Snx10 was knocked down globally or knocked out in osteoclasts. Endocytosis is severely defective in Snx10-deficient osteoclasts, as is extracellular acidification, ruffled border formation, and bone resorption. We also discovered that Snx10 is highly expressed in stomach epithelium, with mutations leading to high stomach pH and low calcium solubilization. Global Snx10-deficiency in mice results in a combined phenotype: osteopetrosis (due to osteoclast defect) and rickets (due to high stomach pH and low calcium availability, resulting in impaired bone mineralization). Osteopetrorickets, the paradoxical association of insufficient mineralization in the context of a positive total body calcium balance, is thought to occur due to the inability of the osteoclasts to maintain normal calcium-phosphorus homeostasis. However, osteoclast-specific Snx10 knockout had no effect on calcium balance, and therefore led to severe osteopetrosis without rickets. Moreover, supplementation with calcium gluconate rescued mice from the rachitic phenotype and dramatically extended life span in global Snx10-deficient mice, suggesting that this may be a life-saving component of the clinical approach to Snx10-dependent human osteopetrosis that has previously gone unrecognized. We conclude that tissue-specific effects of Snx10 mutation need to be considered in clinical approaches to this disease entity. Reliance solely on hematopoietic stem cell transplantation can leave hypocalcemia uncorrected with sometimes fatal consequences. These studies established an essential role for Snx10 in bone homeostasis and underscore the importance of gastric acidification in calcium uptake.
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Rafayelyan S, Meyer P, Radlanski RJ, Minden K, Jost-Brinkmann PG, Präger TM. Effect of methotrexate upon antigen-induced arthritis of the rabbit temporomandibular joint. J Oral Pathol Med 2014; 44:614-21. [PMID: 25243828 DOI: 10.1111/jop.12265] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2014] [Indexed: 01/07/2023]
Abstract
BACKGROUND Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of methotrexate (MTX) on AIA in rabbits by means of three different histological staining methods. METHODS After sensitization, a bilateral arthritis of the TMJ was induced by an intra-articular administration of ovalbumin in 12 New Zealand white rabbits aged 10 weeks. From the 13th week of age, six of the 12 rabbits received weekly intramuscular injections of MTX, and the other six animals remained without therapy. Another six animals served as controls, receiving no treatment or intra-articular injections at all. After euthanasia at the age of 22 weeks, all TMJs were retrieved en bloc. Sagittal sections were cut and stained with haematoxylin-eosin (H-E), Safranin-O for the evaluation of the Mankin score and tartrate-resistant acid phosphatase (TRAP). RESULTS In the arthritis group, a chronic inflammation with degeneration of the articular cartilage was visible. In the MTX group, the signs of cartilage degeneration were significantly reduced compared with the arthritis group. In contrast, the joints in the control group were inconspicuous. A correlation between the Mankin score and TRAP-positive cells could be found. CONCLUSIONS Systemic administration of MTX seems to have a positive effect upon the inflammatory process in the rabbit TMJ but fails to eliminate the sign of arthritis completely.
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Affiliation(s)
- Smbat Rafayelyan
- Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Philipp Meyer
- Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ralf J Radlanski
- Department of Oral Structural Biology, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Kirsten Minden
- German Rheumatism Research Centre Berlin, Berlin, Germany
| | - Paul-Georg Jost-Brinkmann
- Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas M Präger
- Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany
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27
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van Meel E, Klumperman J. TGN exit of the cation-independent mannose 6-phosphate receptor does not require acid hydrolase binding. CELLULAR LOGISTICS 2014; 4:e954441. [PMID: 25610721 DOI: 10.4161/21592780.2014.954441] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 08/07/2014] [Indexed: 12/23/2022]
Abstract
The cation-independent mannose 6-phosphate (Man-6-P) receptor (CI-MPR) binds newly synthesized, Man-6-P-containing lysosomal acid hydrolases in the trans-Golgi network (TGN) for clathrin-mediated transport to endosomes. It has remained unresolved, however, whether acid hydrolase binding is required for exit of the CI-MPR from the TGN. To address this question we used a B cell line derived from a Mucolipidosis type II (MLII)/I-cell disease patient. In MLII patients, acid hydrolases do not acquire the Man-6-P recognition marker and as a consequence do not bind to the CI-MPR. This causes secretion of the majority of the acid hydrolases and a decreased lysosomal activity resulting in typical inclusion bodies. In agreement herewith, ultrastructural analysis of the MLII patient derived B cells showed numerous inclusion bodies with undigested material, which we defined as autolysosomes. By quantitative immuno-electron microscopy we then studied the distribution of the CI-MPR in these cells. We found that the level of co-localization of TGN-localized CI-MPR and clathrin was similar in MLII and control B cells. Moreover, the CI-MPR was readily found in endosomes of MLII cells and the TGN-to-early endosome ratio of CI-MPR labeling was unaltered. These data show that there is no block in TGN exit of the CI-MPR in the absence of Man-6-P-modified acid hydrolases. Notably, late endosomes and inclusion bodies in MLII B cells contained increased levels of the CI-MPR, which likely reflects the reduced degradative capacity of these compartments.
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Affiliation(s)
- Eline van Meel
- Department of Cell Biology; University Medical Center Utrecht ; Utrecht, The Netherlands
| | - Judith Klumperman
- Department of Cell Biology; University Medical Center Utrecht ; Utrecht, The Netherlands
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28
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Rafayelyan S, Radlanski RJ, Minden K, Pischon N, Jost-Brinkmann PG, Präger TM. Histomorphometry in antigen-induced arthritis of the rabbit temporomandibular joint. J Oral Pathol Med 2014; 44:67-74. [PMID: 24935724 DOI: 10.1111/jop.12201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2014] [Indexed: 12/23/2022]
Abstract
BACKGROUND Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of the tumor necrosis factor-alpha (TNF-α) antagonist etanercept on AIA in rabbits by means of three different histological staining methods. METHODS After sensitization, a bilateral arthritis of the TMJ was induced and maintained by repeated intra-articular administrations of ovalbumin in 12 New Zealand white rabbits aged 10 weeks. From the 13th week of age, 6 of the 12 rabbits received weekly subcutaneous injections of etanercept, and the other 6 animals remained without therapy. Another 6 animals served as controls, receiving no treatment or intra-articular injections at all. After euthanasia at the age of 22 weeks, all TMJs were retrieved en bloc. Sagittal sections were cut and stained with hematoxylin-eosin (H-E), Safranin-O for the evaluation of the Mankin score, and tartrate-resistant acid phosphatase (TRAP). RESULTS In the arthritis group, a chronic inflammation with degeneration of the articular cartilage was visible. In the etanercept group, the signs of cartilage degeneration were significantly reduced but present. In contrast, the joints in the control group were inconspicuous. A strong correlation between the Mankin score and TRAP-positive cells could be found. CONCLUSIONS Antigen-induced arthritis causes severe damage in the TMJ of young rabbits. An improvement seems to be achievable by a systemic administration of etanercept.
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Affiliation(s)
- S Rafayelyan
- Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Center for Dental and Craniofacial Sciences, Charité - Universitätsmedizin Berlin, Berlin, Germany
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29
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Role of vesicular trafficking in skeletal dynamics. Curr Opin Pharmacol 2014; 16:7-14. [PMID: 24566133 DOI: 10.1016/j.coph.2014.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 01/06/2023]
Abstract
Vesicular trafficking is critical for the function of bone cells, exemplified by bone diseases such as osteopetrosis, which frequently results from defects in this process. Recent work has further dissected the role of the endolysosomal system in both bone formation by osteoblasts and bone resorption by osteoclasts. This pathway also plays an important role in the communication between these and other cells in bone, through trafficking and degradation of growth factors and their receptors, and microvesicle release. In addition, a crucial role for autophagy in bone remodelling and bone disease is beginning to emerge. These insights into the molecular control of bone remodelling raise the possibility of developing novel therapeutics for bone diseases designed to target specific aspects of this process.
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30
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Kollmann K, Pestka JM, Kühn SC, Schöne E, Schweizer M, Karkmann K, Otomo T, Catala-Lehnen P, Failla AV, Marshall RP, Krause M, Santer R, Amling M, Braulke T, Schinke T. Decreased bone formation and increased osteoclastogenesis cause bone loss in mucolipidosis II. EMBO Mol Med 2013; 5:1871-86. [PMID: 24127423 PMCID: PMC3914524 DOI: 10.1002/emmm.201302979] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 09/06/2013] [Accepted: 09/09/2013] [Indexed: 01/03/2023] Open
Abstract
Mucolipidosis type II (MLII) is a severe multi-systemic genetic disorder caused by missorting of lysosomal proteins and the subsequent lysosomal storage of undegraded macromolecules. Although affected children develop disabling skeletal abnormalities, their pathogenesis is not understood. Here we report that MLII knock-in mice, recapitulating the human storage disease, are runted with accompanying growth plate widening, low trabecular bone mass and cortical porosity. Intralysosomal deficiency of numerous acid hydrolases results in accumulation of storage material in chondrocytes and osteoblasts, and impaired bone formation. In osteoclasts, no morphological or functional abnormalities are detected whereas osteoclastogenesis is dramatically increased in MLII mice. The high number of osteoclasts in MLII is associated with enhanced osteoblastic expression of the pro-osteoclastogenic cytokine interleukin-6, and pharmacological inhibition of bone resorption prevented the osteoporotic phenotype of MLII mice. Our findings show that progressive bone loss in MLII is due to the presence of dysfunctional osteoblasts combined with excessive osteoclastogenesis. They further underscore the importance of a deep skeletal phenotyping approach for other lysosomal diseases in which bone loss is a prominent feature.
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Affiliation(s)
- Katrin Kollmann
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Lacombe J, Karsenty G, Ferron M. Regulation of lysosome biogenesis and functions in osteoclasts. Cell Cycle 2013; 12:2744-52. [PMID: 23966172 DOI: 10.4161/cc.25825] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In order to resorb the mineralized bone extracellular matrix, the osteoclast relies on the generation of a resorption lacuna characterized by the presence of specific proteases and a low pH. Hence, bone resorption by osteoclasts is highly dependent on lysosomes, the organelles specialized in intra- and extracellular material degradation. This is best illustrated by the fact that multiple forms of human osteopetrosis are caused by mutations in genes encoding for lysosomal proteins. Yet, until recently, the molecular mechanisms regulating lysosomal biogenesis and function in osteoclasts were poorly understood. Here we review the latest developments in the study of lysosomal biogenesis and function in osteoclasts with an emphasis on the transcriptional control of these processes.
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Affiliation(s)
- Julie Lacombe
- Institut de Recherches Cliniques de Montréal; Montréal, Québec, Canada
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32
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Szewczyk KA, Fuller K, Chambers TJ. Distinctive subdomains in the resorbing surface of osteoclasts. PLoS One 2013; 8:e60285. [PMID: 23555944 PMCID: PMC3605329 DOI: 10.1371/journal.pone.0060285] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 02/25/2013] [Indexed: 11/19/2022] Open
Abstract
We employed a novel technique to inspect the substrate-apposed surface of activated osteoclasts, the cells that resorb bone, in the scanning electron microscope. The surface revealed unexpected complexity. At the periphery of the cells were circles and crescents of individual or confluent nodules. These corresponded to the podosomes and actin rings that form a 'sealing zone', encircling the resorptive hemivacuole into which protons and enzymes are secreted. Inside these rings and crescents the osteoclast surface was covered with strips and patches of membrane folds, which were flattened against the substrate surface and surrounded by fold-free membrane in which many orifices could be seen. Corresponding regions of folded and fold-free membrane were found by transmission electron microscopy in osteoclasts incubated on bone. We correlated these patterns with the distribution of several proteins crucial to resorption. The strips and patches of membrane folds corresponded in distribution to vacuolar H+-ATPase, and frequently co-localized with F-actin. Cathepsin K localized to F-actin-free foci towards the center of cells with circular actin rings, and at the retreating pole of cells with actin crescents. The chloride/proton antiporter ClC-7 formed a sharply-defined band immediately inside the actin ring, peripheral to vacuolar H+-ATPase. The sealing zone of osteoclasts is permeable to molecules with molecular mass up to 10,000. Therefore, ClC-7 might be distributed at the periphery of the resorptive hemivacuole in order to prevent protons from escaping laterally from the hemivacuole into the sealing zone, where they would dissolve the bone mineral. Since the activation of resorption is attributable to recognition of the αVβ3 ligands bound to bone mineral, such leakage would, by dissolving bone mineral, release the ligands and so terminate resorption. Therefore, ClC-7 might serve not only to provide the counter-ions that enable proton pumping, but also to facilitate resorption by acting as a 'functional sealing zone'.
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Affiliation(s)
- Kinga A. Szewczyk
- Division of Basic Medical Sciences, St George's, University of London, Cranmer Terrace, Tooting, London, United Kingdom
| | - Karen Fuller
- Division of Basic Medical Sciences, St George's, University of London, Cranmer Terrace, Tooting, London, United Kingdom
| | - Tim J. Chambers
- Division of Basic Medical Sciences, St George's, University of London, Cranmer Terrace, Tooting, London, United Kingdom
- * E-mail:
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33
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Voronov I, Ochotny N, Jaumouillé V, Owen C, Manolson MF, Aubin JE. The R740S mutation in the V-ATPase a3 subunit increases lysosomal pH, impairs NFATc1 translocation, and decreases in vitro osteoclastogenesis. J Bone Miner Res 2013; 28:108-18. [PMID: 22865292 DOI: 10.1002/jbmr.1727] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 06/07/2012] [Accepted: 07/16/2012] [Indexed: 01/04/2023]
Abstract
Vacuolar H(+) -ATPase (V-ATPase), a multisubunit enzyme located at the ruffled border and in lysosomes of osteoclasts, is necessary for bone resorption. We previously showed that heterozygous mice with an R740S mutation in the a3 subunit of V-ATPase (+/R740S) have mild osteopetrosis resulting from an ∼90% reduction in proton translocation across osteoclast membranes. Here we show that lysosomal pH is also higher in +/R740S compared with wild-type (+/+) osteoclasts. Both osteoclast number and size were decreased in cultures of +/R740S compared with +/+ bone marrow cells, with concomitant decreased expression of key osteoclast markers (TRAP, cathepsin K, OSCAR, DC-STAMP, and NFATc1), suggesting that low lysosomal pH plays an important role in osteoclastogenesis. To elucidate the molecular mechanism of this inhibition, NFATc1 activation was assessed. NFATc1 nuclear translocation was significantly reduced in +/R740S compared with +/+ cells; however, this was not because of impaired enzymatic activity of calcineurin, the phosphatase responsible for NFATc1 dephosphorylation. Protein and RNA expression levels of regulator of calcineurin 1 (RCAN1), an endogenous inhibitor of NFATc1 activation and a protein degraded in lysosomes, were not significantly different between +/R740S and +/+ osteoclasts, but the RCAN1/NFATc1 ratio was significantly higher in +/R740S versus +/+ cells. The lysosomal inhibitor chloroquine significantly increased RCAN1 accumulation in +/+ cells, consistent with the hypothesis that higher lysosomal pH impairs RCAN1 degradation, leading to a higher RCAN1/NFATc1 ratio and consequently NFATc1 inhibition. Our data indicate that increased lysosomal pH in osteoclasts leads to decreased NFATc1 signaling and nuclear translocation, resulting in a cell autonomous impairment of osteoclastogenesis in vitro.
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Affiliation(s)
- Irina Voronov
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
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34
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Cremasco V, Decker CE, Stumpo D, Blackshear PJ, Nakayama KI, Nakayama K, Lupu TS, Graham DB, Novack DV, Faccio R. Protein kinase C-delta deficiency perturbs bone homeostasis by selective uncoupling of cathepsin K secretion and ruffled border formation in osteoclasts. J Bone Miner Res 2012; 27:2452-63. [PMID: 22806935 PMCID: PMC3498518 DOI: 10.1002/jbmr.1701] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/12/2012] [Accepted: 06/26/2012] [Indexed: 01/27/2023]
Abstract
Bone homeostasis requires stringent regulation of osteoclasts, which secrete proteolytic enzymes to degrade the bone matrix. Despite recent progress in understanding how bone resorption occurs, the mechanisms regulating osteoclast secretion, and in particular the trafficking route of cathepsin K vesicles, remain elusive. Using a genetic approach, we describe the requirement for protein kinase C-delta (PKCδ) in regulating bone resorption by affecting cathepsin K exocytosis. Importantly, PKCδ deficiency does not perturb formation of the ruffled border or trafficking of lysosomal vesicles containing the vacuolar-ATPase (v-ATPase). Mechanistically, we find that cathepsin K exocytosis is controlled by PKCδ through modulation of the actin bundling protein myristoylated alanine-rich C-kinase substrate (MARCKS). The relevance of our finding is emphasized in vivo because PKCδ-/- mice exhibit increased bone mass and are protected from pathological bone loss in a model of experimental postmenopausal osteoporosis. Collectively, our data provide novel mechanistic insights into the pathways that selectively promote secretion of cathepsin K lysosomes independently of ruffled border formation, providing evidence of the presence of multiple mechanisms that regulate lysosomal exocytosis in osteoclasts.
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Affiliation(s)
- Viviana Cremasco
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Corinne E. Decker
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Deborah Stumpo
- Laboratory of Signal transduction; National Institute of Environmental Health Science; Research Triangle Park, NC, 27709; USA
| | - Perry J. Blackshear
- Laboratory of Signal transduction; National Institute of Environmental Health Science; Research Triangle Park, NC, 27709; USA
| | - Keiichi I. Nakayama
- Department of Molecular and Cellular Biology; Medical Institute of Bioregulation; Kyushu University; Fukuoka, Fukuoka 812-8582; JAPAN
| | - Keiko Nakayama
- Department of Developmental Genetics; Center for Translational and Advanced Animal Research; Graduate School of Medicine; Tohoku University; Aoba-ku, Sendai 980-8575; Japan
| | - Traian S. Lupu
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Daniel B. Graham
- Department of Pathology and Immunology; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Deborah V. Novack
- Department of Pathology and Immunology; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Roberta Faccio
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
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35
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Ding Y, Wang J, Wang J, Stierhof YD, Robinson DG, Jiang L. Unconventional protein secretion. TRENDS IN PLANT SCIENCE 2012; 17:606-15. [PMID: 22784825 DOI: 10.1016/j.tplants.2012.06.004] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 06/08/2012] [Accepted: 06/12/2012] [Indexed: 05/11/2023]
Abstract
It is generally believed that protein secretion or exocytosis is achieved via a conventional ER (endoplasmic reticulum)-Golgi-TGN (trans-Golgi network)-PM (plasma membrane) pathway in the plant endomembrane system. However, such signal peptide (SP)-dependent protein secretion cannot explain the increasing number of SP-lacking proteins which are found outside of the PM in plant cells. The process by which such leaderless secretory proteins (LSPs) gain access to the cell exterior is termed unconventional protein secretion (UPS) and has been well-studied in animal and yeast cells, but largely ignored by the plant community. Here, we review the evidence for UPS in plants especially in regard to the recently discovered EXPO (exocyst-positive-organelle).
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Affiliation(s)
- Yu Ding
- School of Life Sciences, Centre for Cell and Developmental Biology, the Chinese University of Hong Kong, Hong Kong, China
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36
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Zhao H. Membrane trafficking in osteoblasts and osteoclasts: new avenues for understanding and treating skeletal diseases. Traffic 2012; 13:1307-14. [PMID: 22759194 DOI: 10.1111/j.1600-0854.2012.01395.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 06/28/2012] [Accepted: 07/03/2012] [Indexed: 12/21/2022]
Abstract
The endocytic and exocytic/secretory pathways are two major intracellular membrane trafficking routes that regulate numerous cellular functions in a variety of cell types. Osteoblasts and osteoclasts, two major bone cells responsible for bone remodeling and homeostasis, are no exceptions. During the past few years, emerging evidence has pinpointed a critical role for endocytic and secretory pathways in osteoblast and osteoclast differentiation and function. The endosomal membrane provides a platform to integrate bone tropic signals of hormones and growth factors in osteoblasts. In osteoclasts, endocytosis, followed by transcytosis, of degraded bone matrix promotes bone resorption. Secretory pathways, especially lysosome secretion, not only participate in bone matrix deposition by osteoblasts and degradation of mineralized bone matrix by osteoclasts; they may also be involved in the coupling of bone resorption and bone formation during bone remodeling. More importantly, mutations in genes encoding regulatory factors within the endocytic and secretory pathways have been identified as causes for bone diseases. Identification of the molecular mechanisms of these genes in bone cells may provide new therapeutic targets for skeletal disorders.
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Affiliation(s)
- Haibo Zhao
- Department of Internal Medicine, Center for Osteoporosis and Bone Metabolic Diseases, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR, 72205, USA.
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37
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DeSelm CJ, Miller BC, Zou W, Beatty WL, van Meel E, Takahata Y, Klumperman J, Tooze SA, Teitelbaum SL, Virgin HW. Autophagy proteins regulate the secretory component of osteoclastic bone resorption. Dev Cell 2011; 21:966-74. [PMID: 22055344 DOI: 10.1016/j.devcel.2011.08.016] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 07/01/2011] [Accepted: 08/19/2011] [Indexed: 01/13/2023]
Abstract
Osteoclasts resorb bone via the ruffled border, whose complex folds are generated by secretory lysosome fusion with bone-apposed plasma membrane. Lysosomal fusion with the plasmalemma results in acidification of the resorptive microenvironment and release of CatK to digest the organic matrix of bone. The means by which secretory lysosomes are directed to fuse with the ruffled border are enigmatic. We show that proteins essential for autophagy, including Atg5, Atg7, Atg4B, and LC3, are important for generating the osteoclast ruffled border, the secretory function of osteoclasts, and bone resorption in vitro and in vivo. Further, Rab7, which is required for osteoclast function, localizes to the ruffled border in an Atg5-dependent manner. Thus, autophagy proteins participate in polarized secretion of lysosomal contents into the extracellular space by directing lysosomes to fuse with the plasma membrane. These findings are in keeping with a putative link between autophagy genes and human skeletal homeostasis.
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Affiliation(s)
- Carl J DeSelm
- Department of Pathology, Washington University Medical School, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
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38
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Petrey AC, Flanagan-Steet H, Johnson S, Fan X, De la Rosa M, Haskins ME, Nairn AV, Moremen KW, Steet R. Excessive activity of cathepsin K is associated with cartilage defects in a zebrafish model of mucolipidosis II. Dis Model Mech 2011; 5:177-90. [PMID: 22046029 PMCID: PMC3291639 DOI: 10.1242/dmm.008219] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The severe pediatric disorder mucolipidosis II (ML-II; also known as I-cell disease) is caused by defects in mannose 6-phosphate (Man-6-P) biosynthesis. Patients with ML-II exhibit multiple developmental defects, including skeletal, craniofacial and joint abnormalities. To date, the molecular mechanisms that underlie these clinical manifestations are poorly understood. Taking advantage of a zebrafish model of ML-II, we previously showed that the cartilage morphogenesis defects in this model are associated with altered chondrocyte differentiation and excessive deposition of type II collagen, indicating that aspects of development that rely on proper extracellular matrix homeostasis are sensitive to decreases in Man-6-P biosynthesis. To further investigate the molecular bases for the cartilage phenotypes, we analyzed the transcript abundance of several genes in chondrocyte-enriched cell populations isolated from wild-type and ML-II zebrafish embryos. Increased levels of cathepsin and matrix metalloproteinase (MMP) transcripts were noted in ML-II cell populations. This increase in transcript abundance corresponded with elevated and sustained activity of several cathepsins (K, L and S) and MMP-13 during early development. Unlike MMP-13, for which higher levels of protein were detected, the sustained activity of cathepsin K at later stages seemed to result from its abnormal processing and activation. Inhibition of cathepsin K activity by pharmacological or genetic means not only reduced the activity of this enzyme but led to a broad reduction in additional protease activity, significant correction of the cartilage morphogenesis phenotype and reduced type II collagen staining in ML-II embryos. Our findings suggest a central role for excessive cathepsin K activity in the developmental aspects of ML-II cartilage pathogenesis and highlight the utility of the zebrafish system to address the biochemical underpinnings of metabolic disease.
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Affiliation(s)
- Aaron C Petrey
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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