-
Frontiers in Bioscience (Landmark... Jun 2023Osteopetrosis represents a rare genetic disease with a wide range of clinical and genetic heterogeneity, which results from osteoclast failure. Although up to 10 genes...
BACKGROUND
Osteopetrosis represents a rare genetic disease with a wide range of clinical and genetic heterogeneity, which results from osteoclast failure. Although up to 10 genes have been identified to be related with osteopetrosis, the pathogenesis of osteopetrosis remains foggy. Disease-specific induced pluripotent stem cells (iPSCs) and gene-corrected disease specific iPSCs provide a platform to generate attractive disease cell models and isogenic control cellular models respectively. The purpose of this study is to rescue the disease causative mutation in osteopetrosis specific induced pluripotent stem cells and provide isogenic control cellular models.
METHODS
Based on our previously established osteopetrosis-specific iPSCs (ADO2-iPSCs), we repaired the point mutation R286W of the gene in ADO2-iPSCs by the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) mediated homologous recombination.
RESULTS
The obtained gene corrected ADO2-iPSCs (GC-ADO2-iPSCs) were characterized in terms of hESC-like morphology, a normal karyotype, expression of pluripotency markers, homozygous repaired sequence of gene, and the ability to differentiate into cells of three germ layers.
CONCLUSIONS
We successfully corrected the point mutation R286W of the gene in ADO2-iPSCs. This isogenic iPSC line is an ideal control cell model for deciphering the pathogenesis of osteopetrosis in future studies.
Topics: Humans; Induced Pluripotent Stem Cells; CRISPR-Cas Systems; Osteopetrosis; Mutation; Chloride Channels
PubMed: 37395026
DOI: 10.31083/j.fbl2806131 -
European Journal of Medical Genetics Jun 2024Osteopetrosis refers to a group of related rare bone diseases characterized by a high bone mass due to impaired bone resorption by osteoclasts. Despite the high bone... (Review)
Review
Osteopetrosis refers to a group of related rare bone diseases characterized by a high bone mass due to impaired bone resorption by osteoclasts. Despite the high bone mass, skeletal strength is compromised and the risk of fracture is high, particularly in the long bones. Osteopetrosis was classically categorized by inheritance pattern into autosomal recessive forms (ARO), which are severe and diagnosed within the first years of life, an intermediate form and an autosomal dominant (ADO) form; the latter with variable clinical severity and typically diagnosed during adolescence or in young adulthood. Subsequently, the AD form was shown to be a result of mutations in the gene CLCN7 encoding for the ClC-7 chloride channel). Traditionally, the diagnosis of osteopetrosis was made on radiograph appearance alone, but recent molecular and genetic advances have enabled a greater fidelity in classification of osteopetrosis subtypes. In the more severe ARO forms (e.g., malignant infantile osteopetrosis MIOP) typical clinical features have severe consequences and often result in death in early childhood. Major complications of ADO are atypical fractures with delay or failure of repair and challenge in orthopedic management. Bone marrow failure, dental abscess, deafness and visual loss are often underestimated and neglected in relation with lack of awareness and expertise. Accordingly, the care of adult patients with osteopetrosis requires a multidisciplinary approach ideally in specialized centers. Apart from hematopoietic stem cell transplantation in certain infantile forms, the treatment of patients with osteopetrosis, has not been standardized and remains supportive. Further clinical studies are needed to improve our knowledge of the natural history, optimum management and impact of osteopetrosis on the lives of patients living with the disorder.
Topics: Osteopetrosis; Humans; Osteoclasts; Adult; Chloride Channels; Mutation
PubMed: 38593953
DOI: 10.1016/j.ejmg.2024.104936 -
Methods in Molecular Biology (Clifton,... 2024Osteoclasts are specialized cells that degrade bone and are essential for bone formation and maintaining bone homeostasis. Excess or deficient activity of these cells...
Osteoclasts are specialized cells that degrade bone and are essential for bone formation and maintaining bone homeostasis. Excess or deficient activity of these cells can significantly alter bone mass, structure, and physical strength, leading to significant morbidity, as in osteoporosis or osteopetrosis, among many other diseases. Protein phosphorylation in osteoclasts plays critical roles in the signaling pathways that govern the production of osteoclasts and regulate their bone-resorbing activity. In this chapter, we describe the isolation of mouse splenocytes and their differentiation into mature osteoclasts on resorptive (e.g., bone) and non-resorptive (e.g., plastic or glass) surfaces, examining matrix resorption by osteoclasts, immunofluorescence staining of these cells, and knocking out genes by CRISPR in the mouse osteoclastogenic cell line RAW264.7.
Topics: Animals; Mice; Osteoclasts; Osteogenesis; Bone Density; Cell Differentiation; Phosphoprotein Phosphatases
PubMed: 38147208
DOI: 10.1007/978-1-0716-3569-8_4 -
Current Osteoporosis Reports Oct 2023Recently, there has been an increasing number of studies on the crosstalk between the bone and the bone marrow and how it pertains to anemia. Here, we discuss four... (Review)
Review
PURPOSE OF REVIEW
Recently, there has been an increasing number of studies on the crosstalk between the bone and the bone marrow and how it pertains to anemia. Here, we discuss four heritable clinical syndromes contrasting those in which anemia affects bone growth and development, with those in which abnormal bone development results in anemia, highlighting the multifaceted interactions between skeletal development and hematopoiesis.
RECENT FINDINGS
Anemia results from both inherited and acquired disorders caused by either impaired production or premature destruction of red blood cells or blood loss. The downstream effects on bone development and growth in patients with anemia often constitute an important part of their clinical condition. We will discuss the interdependence of abnormal bone development and growth and hematopoietic abnormalities, with a focus on the erythroid lineage. To illustrate those points, we selected four heritable anemias that arise from either defective hematopoiesis impacting the skeletal system (the hemoglobinopathies β-thalassemia and sickle cell disease) versus defective osteogenesis resulting in impaired hematopoiesis (osteopetrosis). Finally, we will discuss recent findings in Diamond Blackfan anemia, an intrinsic disorder of both the erythron and the bone. By focusing on four representative hereditary hematopoietic disorders, this complex relationship between bone and blood should lead to new areas of research in the field.
Topics: Humans; Bone Marrow; Anemia; Hematopoiesis; Bone and Bones
PubMed: 37436584
DOI: 10.1007/s11914-023-00809-3 -
Journal of Molecular Medicine (Berlin,... Apr 2024Osteocalcin (OC) is the most abundant non-collagenous and osteoblast-secreted protein in bone. It consists of two forms such as carboxylated OC (cOC) and... (Review)
Review
Current knowledge of bone-derived factor osteocalcin: its role in the management and treatment of diabetes mellitus, osteoporosis, osteopetrosis and inflammatory joint diseases.
Osteocalcin (OC) is the most abundant non-collagenous and osteoblast-secreted protein in bone. It consists of two forms such as carboxylated OC (cOC) and undercarboxylated OC (ucOC). While cOC promotes bone mineralization and increases bone strength, ucOC is regarded an endocrinologically active form that may have several functions in multiple end organs and tissues. Total OC (tOC) includes both of these forms (cOC and ucOC) and is considered a marker of bone turnover in clinical settings. Most of the data on OC is limited to preclinical studies and therefore may not accurately reflect the situation in clinical conditions. For the stated reason, the aim of this review was not only to summarize current knowledge of all forms of OC and characterize its role in diabetes mellitus, osteoporosis, osteopetrosis, inflammatory joint diseases, but also to provide new interpretations of its involvement in the management and treatment of aforementioned diseases. In this context, special emphasis was placed on available clinical trials. Significantly lower levels of tOC and ucOC could be associated with the risk of type 2 diabetes mellitus. On the contrary, tOC level does not seem to be a good indicator of high bone turnover status in postmenopausal osteoporosis, osteoarthritis and rheumatoid arthritis. The associations between several pharmacological drugs used to treat all disorders mentioned above and OC levels have also been provided. From this perspective, OC may serve as a medium through which certain medications can influence glucose metabolism, body weight, adiponectin secretion, and synovial inflammation.
Topics: Humans; Diabetes Mellitus, Type 2; Osteocalcin; Osteopetrosis; Osteoporosis; Joint Diseases; Biomarkers
PubMed: 38363329
DOI: 10.1007/s00109-024-02418-8 -
Genes Jul 2023Mutations in the mouse microphthalmia-associated transcription factor () gene affect retinal pigment epithelium (RPE) differentiation and development and can lead to...
Mutations in the mouse microphthalmia-associated transcription factor () gene affect retinal pigment epithelium (RPE) differentiation and development and can lead to hypopigmentation, microphthalmia, deafness, and blindness. For instance, an association has been established between loss-of-function mutations in the mouse gene and a variety of human retinal diseases, including Waardenburg type 2 and Tietz syndromes. Although there is evidence showing that mice with the homozygous mutation manifest microphthalmia and osteopetrosis, there are limited or no data on the effects of the heterozygous condition in the eye. mice can therefore be regarded as an important model system for the study of human disease. Thus, we characterized mice at 1, 3, 12, and 18 months old in comparison with age-matched wild-type mice. The light- and dark-adapted electroretinogram (ERG) recordings showed progressive cone-rod dystrophy in mice. The RPE response was reduced in the mutant in all age groups studied. Progressive loss of pigmentation was found in mice. Histological retinal sections revealed evidence of retinal degeneration in mice at older ages. For the first time, we report a mouse model of progressive cone-rod dystrophy and RPE dysfunction with a mutation in the gene.
Topics: Animals; Mice; Cone-Rod Dystrophies; Microphthalmia-Associated Transcription Factor; Microphthalmos; Retinal Dystrophies; Retinal Pigment Epithelium
PubMed: 37510362
DOI: 10.3390/genes14071458 -
Pediatric Radiology Jun 2024Osteopetrosis describes several types of rare sclerosing bone dysplasias of varying clinical and radiographic severity. The classic autosomal dominant subtype emerges... (Review)
Review
Osteopetrosis describes several types of rare sclerosing bone dysplasias of varying clinical and radiographic severity. The classic autosomal dominant subtype emerges most often in adolescence but can present from infancy through adulthood. The autosomal recessive osteopetrosis, or "malignant infantile osteopetrosis," presents in infancy with a grimmer prognosis, though the autosomal dominant forms (often mislabeled as "benign") actually can have life-threatening consequences as well. Often osteopetrosis is detected due to skeletal findings on radiographs performed to evaluate injury or as an incidental finding during evaluation for illness. Given the varied phenotypic severity and presentations at different ages, radiologists play an integral role in the care of these patients both in diagnosis and in clinical evaluation and monitoring. A deeper understanding of the underlying genetic basis of the disease can aid in the radiologist in diagnosis and in anticipation of unique complications. An overview of current clinical management is also discussed.
Topics: Humans; Osteopetrosis; Child; Diagnosis, Differential; Adolescent; Infant
PubMed: 38483591
DOI: 10.1007/s00247-024-05899-4 -
Radiologie (Heidelberg, Germany) Jun 2024We were looking for an osteoporosis screening in computed tomography (CT) exams, simple and without additional examinations. We hypothesized that the criterion of...
BACKGROUND
We were looking for an osteoporosis screening in computed tomography (CT) exams, simple and without additional examinations. We hypothesized that the criterion of "decreasing cortical thickness", may have an influence on the hard palate. Therefore, we investigated whether thickness of the hard palate (HPT) may serve as an indicator of osteoporosis for patients imaged for other reasons.
METHODS
Patients with dual-energy x-ray absorptiometry (DXA) and CT were identified by a radiology information system (RIS)-based, full-text search. Measurement of thickness of hard palate done in existing CT image by radiologist and dentist and compared with available findings and DXA measurements.
RESULTS
We identified a "test group": 57 patients with DXA and CT available out of 449 patient population and we selected further 70 patients without bone diseases as "control groups". The measurements showed that HPT correlated with age and bone density. The mean HPT was 2.4 mm in normal, 0.9 mm in osteopenia, 0.8 mm in osteoporosis and 5.3 mm in osteopetrosis case. No bone "healthy" patient fell below 1 mm. The relationship between bone density and HPT has not been described previously. HPT was highest in the bone-healthy group and decreased with age, osteopenia, and osteoporosis. Osteopetrosis, as a disease with increased bone density showed an increase in HPT.
CONCLUSIONS
HPT correlates with bone disease. We propose a new criterion for assessment on CT and digital volume tomography (DVT) or cone beam computed tomography (CBCT). A threshold of 1.0 mm when applying a simple measurement of HPT on Head CT or DVT may serve as an indicator for potential osteopenia or osteoporosis as incidental finding without extra imaging further diagnosis and treatment leading to early notice of Osteoporosis.
PubMed: 38842551
DOI: 10.1007/s00117-024-01318-9 -
Impaired Autophagic Clearance with a Gain-of-Function Variant of the Lysosomal Cl/H Exchanger ClC-7.Biomolecules Dec 2023ClC-7 is a ubiquitously expressed voltage-gated Cl/H exchanger that critically contributes to lysosomal ion homeostasis. Together with its β-subunit Ostm1, ClC-7...
ClC-7 is a ubiquitously expressed voltage-gated Cl/H exchanger that critically contributes to lysosomal ion homeostasis. Together with its β-subunit Ostm1, ClC-7 localizes to lysosomes and to the ruffled border of osteoclasts, where it supports the acidification of the resorption lacuna. Loss of ClC-7 or Ostm1 leads to osteopetrosis accompanied by accumulation of storage material in lysosomes and neurodegeneration. Interestingly, not all osteopetrosis-causing mutations from patients are associated with a loss of ion transport. Some rather result in an acceleration of voltage-dependent ClC-7 activation. Recently, a gain-of-function variant, ClC-7, that yields larger ion currents upon heterologous expression, was identified in two patients with neurodegeneration, organomegaly and albinism. However, neither the patients nor a mouse model that carried the equivalent mutation developed osteopetrosis, although expression of ClC-7 induced the formation of enlarged intracellular vacuoles. Here, we investigated how, in transfected cells with mutant ClC-7, the substitution of this tyrosine impinged on the morphology and function of lysosomes. Combinations of the tyrosine mutation with mutations that either uncouple Cl from H counter-transport or strongly diminish overall ion currents were used to show that increased ClC-7 Cl/H exchange activity is required for the formation of enlarged vacuoles by membrane fusion. Degradation of endocytosed material was reduced in these compartments and resulted in an accumulation of lysosomal storage material. In cells expressing the ClC-7 gain-of-function mutant, autophagic clearance was largely impaired, resulting in a build-up of autophagic material.
Topics: Mice; Animals; Humans; Osteopetrosis; Gain of Function Mutation; Mutation; Lysosomes; Tyrosine; Chloride Channels
PubMed: 38136669
DOI: 10.3390/biom13121799 -
Nature Communications Feb 2024Osteoclasts are over-activated as we age, which results in bone loss. Src deficiency in mice leads to severe osteopetrosis due to a functional defect in osteoclasts,...
Osteoclasts are over-activated as we age, which results in bone loss. Src deficiency in mice leads to severe osteopetrosis due to a functional defect in osteoclasts, indicating that Src function is essential in osteoclasts. G-protein-coupled receptors (GPCRs) are the targets for ∼35% of approved drugs but it is still unclear how GPCRs regulate Src kinase activity. Here, we reveal that GPR54 activation by its natural ligand Kisspeptin-10 (Kp-10) causes Dusp18 to dephosphorylate Src at Tyr 416. Mechanistically, Gpr54 recruits both active Src and the Dusp18 phosphatase at its proline/arginine-rich motif in its C terminus. We show that Kp-10 binding to Gpr54 leads to the up-regulation of Dusp18. Kiss1, Gpr54 and Dusp18 knockout mice all exhibit osteoclast hyperactivation and bone loss, and Kp-10 abrogated bone loss by suppressing osteoclast activity in vivo. Therefore, Kp-10/Gpr54 is a promising therapeutic target to abrogate bone resorption by Dusp18-mediated Src dephosphorylation.
Topics: Animals; Mice; Osteoclasts; Kisspeptins; Receptors, G-Protein-Coupled; src-Family Kinases; Mice, Knockout; Bone Resorption; Receptors, Kisspeptin-1
PubMed: 38346942
DOI: 10.1038/s41467-024-44852-9