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Erkhembaatar M, Gu DR, Lee SH, Yang YM, Park S, Muallem S, Shin DM, Kim MS. Lysosomal Ca 2+ Signaling is Essential for Osteoclastogenesis and Bone Remodeling. J Bone Miner Res 2017; 32:385-396. [PMID: 27589205 PMCID: PMC9850942 DOI: 10.1002/jbmr.2986] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 01/21/2023]
Abstract
Lysosomal Ca2+ emerges as a critical component of receptor-evoked Ca2+ signaling and plays a crucial role in many lysosomal and physiological functions. Lysosomal Ca2+ release is mediated by the transient receptor potential (TRP) family member TRPML1, mutations that cause the lysosomal storage disease mucolipidosis type 4. Lysosomes play a key role in osteoclast function. However, nothing is known about the role of lysosomal Ca2+ signaling in osteoclastogenesis and bone metabolism. In this study, we addressed this knowledge gap by studying the role of lysosomal Ca2+ signaling in osteoclastogenesis, osteoclast and osteoblast functions, and bone homeostasis in vivo. We manipulated lysosomal Ca2+ signaling by acute knockdown of TRPML1, deletion of TRPML1 in mice, pharmacological inhibition of lysosomal Ca2+ influx, and depletion of lysosomal Ca2+ storage using the TRPML agonist ML-SA1. We found that knockdown and deletion of TRPML1, although it did not have an apparent effect on osteoblast differentiation and bone formation, markedly attenuated osteoclast function, RANKL-induced cytosolic Ca2+ oscillations, inhibited activation of NFATc1 and osteoclastogenesis-controlling genes, suppressed the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and markedly reduced the differentiation of bone marrow-derived macrophages into osteoclasts. Moreover, deletion of TRPML1 resulted in enlarged lysosomes, inhibition of lysosomal secretion, and attenuated the resorptive activity of mature osteoclasts. Notably, depletion of lysosomal Ca2+ with ML-SA1 similarly abrogated RANKL-induced Ca2+ oscillations and MNC formation. Deletion of TRPML1 in mice reduced the TRAP-positive bone surfaces and impaired bone remodeling, resulting in prominent osteopetrosis. These findings demonstrate the essential role of lysosomal Ca2+ signaling in osteoclast differentiation and mature osteoclast function, which play key roles in bone homeostasis. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Munkhsoyol Erkhembaatar
- Department of Oral Physiology, and Institute of Biomaterial-Implant, College of Dentistry, Wonkwang University, Iksan, Republic of Korea.,Department of Physiology, School of Pharmacy and Bio-Medicine, Mongolian National University of Medical Science, Ulaanbaatar, Mongolia
| | - Dong Ryun Gu
- Center for Metabolic Function Regulation (CMFR), School of Medicine, Wonkwang University, Iksan, Republic of Korea.,Department of Oral Microbiology and Immunology, College of Dentistry, Wonkwang University, Iksan, Republic of Korea
| | - Seoung Hoon Lee
- Center for Metabolic Function Regulation (CMFR), School of Medicine, Wonkwang University, Iksan, Republic of Korea.,Department of Oral Microbiology and Immunology, College of Dentistry, Wonkwang University, Iksan, Republic of Korea
| | - Yu-Mi Yang
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea
| | - Soonhong Park
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Dong Min Shin
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea
| | - Min Seuk Kim
- Department of Oral Physiology, and Institute of Biomaterial-Implant, College of Dentistry, Wonkwang University, Iksan, Republic of Korea
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Geer JS, Skinner SA, Goldin E, Holden KR. Mucolipidosis type IV: a subtle pediatric neurodegenerative disorder. Pediatr Neurol 2010; 42:223-6. [PMID: 20159435 PMCID: PMC2824620 DOI: 10.1016/j.pediatrneurol.2009.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 09/22/2009] [Accepted: 10/12/2009] [Indexed: 11/28/2022]
Abstract
The mucolipidoses are a heterogeneous group of autosomal recessive neurodegenerative lysosomal storage disorders. Mucolipidosis type IV is rare; it is seen predominantly in the Ashkenazi Jewish population and usually presents with global neurodevelopmental delays in infancy, subtle corneal opacifications or clouding, and very slowly progressive neurodegeneration over many years. Elevation of serum gastrin is reported; findings from x-rays of bone and joints and lysosomal studies are normal. Reported here are two cases of mucolipidosis type IV in children not of Ashkenazi Jewish origin who presented during infancy with nonspecific global psychomotor delays, generalized hypotonia, and mild corneal abnormalities, but remained undiagnosed for years. A rare gene mutation in MCOLN1 was confirmed in one of the two patients, in addition to abnormal serum gastrin levels. More striking was the length of time that these children eluded detection of their final diagnosis.
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Affiliation(s)
| | | | - Ehud Goldin
- Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Kenton R. Holden
- Greenwood Genetic Center, Greenwood, South Carolina, Departments of Neurosciences and Pediatrics, Medical University of South Carolina, Charleston, South Carolina
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