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Hofstaetter JG, Atkins GJ, Kato H, Kogawa M, Blouin S, Misof BM, Roschger P, Evdokiou A, Yang D, Solomon LB, Findlay DM, Ito N. A Mild Case of Autosomal Recessive Osteopetrosis Masquerading as the Dominant Form Involving Homozygous Deep Intronic Variations in the CLCN7 Gene. Calcif Tissue Int 2022; 111:430-444. [PMID: 35618777 PMCID: PMC9474465 DOI: 10.1007/s00223-022-00988-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 05/06/2022] [Indexed: 11/28/2022]
Abstract
Osteopetrosis is a heterogeneous group of rare hereditary diseases characterized by increased bone mass of poor quality. Autosomal-dominant osteopetrosis type II (ADOII) is most often caused by mutation of the CLCN7 gene leading to impaired bone resorption. Autosomal recessive osteopetrosis (ARO) is a more severe form and is frequently accompanied by additional morbidities. We report an adult male presenting with classical clinical and radiological features of ADOII. Genetic analyses showed no amino-acid-converting mutation in CLCN7 but an apparent haploinsufficiency and suppression of CLCN7 mRNA levels in peripheral blood mononuclear cells. Next generation sequencing revealed low-frequency intronic homozygous variations in CLCN7, suggesting recessive inheritance. In silico analysis of an intronic duplication c.595-120_595-86dup revealed additional binding sites for Serine- and Arginine-rich Splicing Factors (SRSF), which is predicted to impair CLCN7 expression. Quantitative backscattered electron imaging and histomorphometric analyses revealed bone tissue and material abnormalities. Giant osteoclasts were present and additionally to lamellar bone, and abundant woven bone and mineralized cartilage were observed, together with increased frequency and thickness of cement lines. Bone mineralization density distribution (BMDD) analysis revealed markedly increased average mineral content of the dense bone (CaMean T-score + 10.1) and frequency of bone with highest mineral content (CaHigh T-score + 19.6), suggesting continued mineral accumulation and lack of bone remodelling. Osteocyte lacunae sections (OLS) characteristics were unremarkable except for an unusually circular shape. Together, our findings suggest that the reduced expression of CLCN7 mRNA in osteoclasts, and possibly also osteocytes, causes poorly remodelled bone with abnormal bone matrix with high mineral content. This together with the lack of adequate bone repair mechanisms makes the material brittle and prone to fracture. While the skeletal phenotype and medical history were suggestive of ADOII, genetic analysis revealed that this is a possible mild case of ARO due to deep intronic mutation.
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Affiliation(s)
- Jochen G Hofstaetter
- 1st Medical Dept., Hanusch Hospital, Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, Vienna, Austria
- Michael Ogon Laboratory, Orthopaedic Hospital Vienna-Speising, Vienna, Austria
| | - Gerald J Atkins
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia.
| | - Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan
| | - Masakazu Kogawa
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia
| | - Stéphane Blouin
- 1st Medical Dept., Hanusch Hospital, Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, Vienna, Austria
| | - Barbara M Misof
- 1st Medical Dept., Hanusch Hospital, Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, Vienna, Austria
| | - Paul Roschger
- 1st Medical Dept., Hanusch Hospital, Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, Vienna, Austria
| | - Andreas Evdokiou
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia
| | - Dongqing Yang
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia
| | - Lucian B Solomon
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia
- Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - David M Findlay
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia
| | - Nobuaki Ito
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, Adelaide Health and Medical Sciences Building, The University of Adelaide, North Terrace, Adelaide, SA, 5005, Australia
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan
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Essex AL, Huot JR, Deosthale P, Wagner A, Figueras J, Davis A, Damrath J, Pin F, Wallace J, Bonetto A, Plotkin LI. Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) R47H Variant Causes Distinct Age- and Sex-Dependent Musculoskeletal Alterations in Mice. J Bone Miner Res 2022; 37:1366-1381. [PMID: 35575023 PMCID: PMC9307075 DOI: 10.1002/jbmr.4572] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 04/25/2022] [Accepted: 05/11/2022] [Indexed: 12/05/2022]
Abstract
Previous studies proposed the Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), a receptor expressed in myeloid cells including microglia in brain and osteoclasts in bone, as a link between brain and bone disease. The TREM2 R47H variant is a known risk factor for Alzheimer's disease (AD), the most common form of dementia. To investigate whether altered TREM2 signaling could contribute to bone and skeletal muscle loss, independently of central nervous system defects, we used mice globally hemizygous for the TREM2 R47H variant (TREM2R47H/+ ), which do not exhibit AD pathology, and wild-type (WT) littermate control mice. Dxa/Piximus showed bone loss in female TREM2R47H/+ animals between 4 and 13 months of age and reduced cancellous and cortical bone (measured by micro-computed tomography [μCT]) at 13 months, which stalled out by 20 months of age. In addition, they exhibited decreased femoral biomechanical properties measured by three-point bending at 13 months of age, but not at 4 or 20 months. Male TREM2R47H/+ animals had decreased trabecular bone geometry but increased ultimate strain and failure force at 20 months of age versus WT. Only male TREM2R47H/+ osteoclasts differentiated more ex vivo after 7 days with receptor activator of nuclear factor κB ligand (RANKL)/macrophage colony-stimulating factor (M-CSF) compared to WT littermates. Yet, estrogen receptor alpha expression was higher in female and male TREM2R47H/+ osteoclasts compared to WT mice. However, female TREM2R47H/+ osteoclasts expressed less complement 3 (C3), an estrogen responsive element, and increased protein kinase B (Akt) activity, suggesting altered estrogen signaling in TREM2R47H/+ cells. Despite lower bone volume/strength in TREM2R47H/+ mice, skeletal muscle function measured by plantar flexion and muscle contractility was increased in 13-month-old female mutant mice. Overall, these data demonstrate that an AD-associated TREM2 variant can alter bone and skeletal muscle strength in a sex-dimorphic manner independent of central neuropathology, potentially mediated through changes in osteoclastic intracellular signaling. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Alyson L. Essex
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
- Roudebush Veterans Administration Medical CenterIndianapolisINUSA
- Indiana Center for Musculoskeletal HealthIndianapolisINUSA
| | - Joshua R. Huot
- Indiana Center for Musculoskeletal HealthIndianapolisINUSA
- Department of SurgeryIndiana University School of MedicineIndianapolisINUSA
| | - Padmini Deosthale
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
- Roudebush Veterans Administration Medical CenterIndianapolisINUSA
| | - Alison Wagner
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - Jorge Figueras
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - Azaria Davis
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - John Damrath
- Weldon School of Biomedical EngineeringPurdue UniversityWest LafayetteINUSA
| | - Fabrizio Pin
- Indiana Center for Musculoskeletal HealthIndianapolisINUSA
- Department of SurgeryIndiana University School of MedicineIndianapolisINUSA
- Simon Comprehensive Cancer CenterIndiana UniversityIndianapolisINUSA
| | - Joseph Wallace
- Roudebush Veterans Administration Medical CenterIndianapolisINUSA
- Indiana Center for Musculoskeletal HealthIndianapolisINUSA
- Department of Biomechanical EngineeringIndiana University‐Purdue University IndianapolisIndianapolisINUSA
| | - Andrea Bonetto
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
- Indiana Center for Musculoskeletal HealthIndianapolisINUSA
- Department of SurgeryIndiana University School of MedicineIndianapolisINUSA
- Simon Comprehensive Cancer CenterIndiana UniversityIndianapolisINUSA
| | - Lilian I. Plotkin
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
- Roudebush Veterans Administration Medical CenterIndianapolisINUSA
- Indiana Center for Musculoskeletal HealthIndianapolisINUSA
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Ferrer I. The Primary Microglial Leukodystrophies: A Review. Int J Mol Sci 2022; 23:ijms23116341. [PMID: 35683020 PMCID: PMC9181167 DOI: 10.3390/ijms23116341] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022] Open
Abstract
Primary microglial leukodystrophy or leukoencephalopathy are disorders in which a genetic defect linked to microglia causes cerebral white matter damage. Pigmented orthochromatic leukodystrophy, adult-onset orthochromatic leukodystrophy associated with pigmented macrophages, hereditary diffuse leukoencephalopathy with (axonal) spheroids, and adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) are different terms apparently used to designate the same disease. However, ALSP linked to dominantly inherited mutations in CSF1R (colony stimulating factor receptor 1) cause CSF-1R-related leukoencephalopathy (CRP). Yet, recessive ALSP with ovarian failure linked to AARS2 (alanyl-transfer (t)RNA synthase 2) mutations (LKENP) is a mitochondrial disease and not a primary microglial leukoencephalopathy. Polycystic membranous lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL; Nasu–Hakola disease: NHD) is a systemic disease affecting bones, cerebral white matter, selected grey nuclei, and adipose tissue The disease is caused by mutations of one of the two genes TYROBP or TREM2, identified as PLOSL1 and PLOSL2, respectively. TYROBP associates with receptors expressed in NK cells, B and T lymphocytes, dendritic cells, monocytes, macrophages, and microglia. TREM2 encodes the protein TREM2 (triggering receptor expressed on myeloid cells 2), which forms a receptor signalling complex with TYROBP in macrophages and dendritic cells. Rather than pure microglial leukoencephalopathy, NHD can be considered a multisystemic “immunological” disease.
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Affiliation(s)
- Isidro Ferrer
- Network Centre of Biomedical Research of Neurodegenerative Diseases (CIBERNED), Department of Pathology and Experimental Therapeutics, Bellvitge Biomedical Research Institute (IDIBELL), University of Barcelona, 08907 Barcelona, L'Hospitalet de Llobregat, Spain
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The NGF R100W Mutation Specifically Impairs Nociception without Affecting Cognitive Performance in a Mouse Model of Hereditary Sensory and Autonomic Neuropathy Type V. J Neurosci 2019; 39:9702-9715. [PMID: 31685654 DOI: 10.1523/jneurosci.0688-19.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 10/01/2019] [Accepted: 10/27/2019] [Indexed: 12/22/2022] Open
Abstract
Nerve growth factor (NGF) is a key mediator of nociception, acting during the development and differentiation of dorsal root ganglion (DRG) neurons, and on adult DRG neuron sensitization to painful stimuli. NGF also has central actions in the brain, where it regulates the phenotypic maintenance of cholinergic neurons. The physiological function of NGF as a pain mediator is altered in patients with Hereditary Sensory and Autonomic Neuropathy type V (HSAN V), caused by the 661C>T transition in the Ngf gene, resulting in the R100W missense mutation in mature NGF. Homozygous HSAN V patients present with congenital pain insensitivity, but are cognitively normal. This led us to hypothesize that the R100W mutation may differentially affect the central and peripheral actions of NGF. To test this hypothesis and provide a mechanistic basis to the HSAN V phenotype, we generated transgenic mice harboring the human 661C>T mutation in the Ngf gene and studied both males and females. We demonstrate that heterozygous NGFR100W/wt mice display impaired nociception. DRG neurons of NGFR100W/wt mice are morphologically normal, with no alteration in the different DRG subpopulations, whereas skin innervation is reduced. The NGFR100W protein has reduced capability to activate pain-specific signaling, paralleling its reduced ability to induce mechanical allodynia. Surprisingly, however, NGFR100W/wt mice, unlike heterozygous mNGF+/- mice, show no learning or memory deficits, despite a reduction in secretion and brain levels of NGF. The results exclude haploinsufficiency of NGF as a mechanistic cause for heterozygous HSAN V mice and demonstrate a specific effect of the R100W mutation on nociception.SIGNIFICANCE STATEMENT The R100W mutation in nerve growth factor (NGF) causes Hereditary Sensory and Autonomic Neuropathy type V, a rare disease characterized by impaired nociception, even in apparently clinically silent heterozygotes. For the first time, we generated and characterized heterozygous knock-in mice carrying the human R100W-mutated allele (NGFR100W/wt). Mutant mice have normal nociceptor populations, which, however, display decreased activation of pain transduction pathways. NGFR100W interferes with peripheral and central NGF bioavailability, but this does not impact on CNS function, as demonstrated by normal learning and memory, in contrast with heterozygous NGF knock-out mice. Thus, a point mutation allows neurotrophic and pronociceptive functions of NGF to be split, with interesting implications for the treatment of chronic pain.
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