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Liu X, Dong M, Li Y, Li L, Zhang Y, Zhou A, Wang D. Structural characterization of Russula griseocarnosa polysaccharide and its improvement on hematopoietic function. Int J Biol Macromol 2024; 263:130355. [PMID: 38395281 DOI: 10.1016/j.ijbiomac.2024.130355] [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] [Received: 11/14/2023] [Revised: 02/19/2024] [Accepted: 02/19/2024] [Indexed: 02/25/2024]
Abstract
The hematopoietic function of a polysaccharide derived from Russula griseocarnosa was demonstrated in K562 cells, and subsequently purified through chromatography to obtain RGP1. RGP1 is a galactan composed of 1,6-α-D-Galp as the main chain, with partial substitutions. A -CH3 substitution was detected at O-3 of 1,6-α-D-Galp. The possible branches at O-2 of 1,6-α-D-Galp was α-L-Fucp. In mice with cyclophosphamide (CTX)-induced hematopoietic dysfunction, RGP1 alleviated bone marrow damage and multinucleated giant cell infiltration of the spleen, increased the number of long-term hematopoietic stem cells, and regulated the levels of myeloid cells in the peripheral blood. Furthermore, RGP1 promoted the differentiation of activated T cells and CD4+ T cells without affecting natural killer cells and B cells. Proteomic analysis, detection of cytokines, and western blotting revealed that RGP1 could alleviate hematopoietic dysfunction by promoting the activation of CD4+ T cells and the Janus kinase/ signal transducer and activator of transcription 3 pathway. The present study provides experimental evidence to support the application of RGP1 in CTX-induced hematopoietic dysfunction.
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Affiliation(s)
- Xin Liu
- School of Life Sciences, Jilin University, Changchun 130012, China; School of Health Science and Biomedical Engineering, Hebei University of Technology, Tianjin 300131, China.
| | - Mingyuan Dong
- School of Life Sciences, Jilin University, Changchun 130012, China.
| | - Yuan Li
- School of Life Sciences, Jilin University, Changchun 130012, China.
| | - Lanzhou Li
- Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, School of Plant Protection, Jilin Agricultural University, Changchun 130118, China.
| | - Yongfeng Zhang
- School of Life Sciences, Jilin University, Changchun 130012, China.
| | - Andong Zhou
- School of Life Sciences, Jilin University, Changchun 130012, China.
| | - Di Wang
- School of Life Sciences, Jilin University, Changchun 130012, China; Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, School of Plant Protection, Jilin Agricultural University, Changchun 130118, China.
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2
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Liu G, Zhu G, Wu X, Tang Z, Shao W, Wang M, Xia H, Sun Q, Yan M. Thy-1 knockdown promotes the osteogenic differentiation of GMSCs via the Wnt/β-catenin pathway. J Cell Mol Med 2023; 27:3805-3815. [PMID: 37786319 PMCID: PMC10718136 DOI: 10.1111/jcmm.17955] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 10/04/2023] Open
Abstract
Gingival mesenchymal stem cells (GMSCs) are newly developed seed cells for tissue engineering owing to their easy isolation, abundance and high growth rates. Thy-1 is an important regulatory molecule in the differentiation of mesenchymal stem cells (MSCs). In this study, we investigated the function of Thy-1 in the osteogenic differentiation of GMSCs by reducing the expression of Thy-1 using a lentivirus. The results demonstrated that Thy-1 knockdown promoted the osteogenic differentiation of GMSCs in vitro. Validation by RNA-seq revealed an obvious decrease in Vcam1 and Sox9 gene expression with Thy-1 knockdown. Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that the differentially expressed genes were enriched in the Wnt signalling pathway. We further demonstrated that Thy-1 knockdown promoted osteogenic differentiation of GMSCs by activating the Wnt/β-catenin signalling pathway. Therefore, Thy-1 has a key regulatory role in the differentiation of GMSCs and maybe a core molecule connecting transcription factors related to the differentiation of MSCs. Our study also highlighted the potential of Thy-1 to modify MSCs, which may help improve their use in tissue engineering.
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Affiliation(s)
- Gufeng Liu
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Guixin Zhu
- The State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of StomatologySichuan UniversityChengduChina
| | - Xiaoyi Wu
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Ziqiao Tang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Wenjun Shao
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Min Wang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
- Department of Oral Implantology, Hospital and School of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Haibin Xia
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
- Department of Oral Implantology, Hospital and School of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Quan Sun
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
- Center for Prosthodontics and Implant Dentistry, Optics Valley Branch, School and Hospital of StomatologyWuhan UniversityWuhanPeople's Republic of China
| | - Mingdong Yan
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key lab of Fujian College and University, School and Hospital of StomatologyFujian Medical UniversityFuzhouPeople's Republic of China
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Yu F, Li F, Yu P, Zhou B, Ye L. Identification and characterization of NFATc1+ skeletal stem cells in bone regeneration. Cell Rep 2022; 41:111599. [DOI: 10.1016/j.celrep.2022.111599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 04/06/2022] [Accepted: 10/13/2022] [Indexed: 11/09/2022] Open
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The Osteogenesis Imperfecta Type V Mutant BRIL/IFITM5 Promotes Transcriptional Activation of MEF2, NFATc, and NR4A in Osteoblasts. Int J Mol Sci 2022; 23:ijms23042148. [PMID: 35216266 PMCID: PMC8875491 DOI: 10.3390/ijms23042148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 11/18/2022] Open
Abstract
BRIL (bone restricted ifitm-like; also known as IFITM5) is a transmembrane protein expressed in osteoblasts. Although its role in skeletal development and homeostasis is unknown, mutations in BRIL result in rare dominant forms of osteogenesis imperfecta. The pathogenic mechanism has been proposed to be a gain-of or neomorphic function. To understand the function of BRIL and its OI type V mutant (MALEP BRIL) and whether they could activate signaling pathways in osteoblasts, we performed a luciferase reporter assay screen based on the activity of 26 transcription factors. When overexpressed in MC3T3-E1 and MLO-A5 cells, the MALEP BRIL activated the reporters dependent on MEF2, NFATc, and NR4A significantly more. Additional co-transfection experiments with MEF2C and NFATc1 and a number of their modulators (HDAC4, calcineurin, RCAN, FK506) confirmed the additive or synergistic activation of the pathways by MALEP, and suggested a coordinated regulation involving calcineurin. Endogenous levels of Nr4a members, as well as Ptgs2, were upregulated by MALEP BRIL. Y2H and co-immunoprecipitation indicated that BRIL interacted with CAML, but its contribution as the most upstream stimulator of the Ca2+-calcineurin-MEF2/NFATc cascade was not confirmed convincingly. Altogether the data presented provide the first ever readout to monitor for BRIL activity and suggest a potential gain-of-function causative effect for MALEP BRIL in OI type V, leading to perturbed signaling events and gene expression.
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Duddu S, Chakrabarti R, Ghosh A, Shukla PC. Hematopoietic Stem Cell Transcription Factors in Cardiovascular Pathology. Front Genet 2020; 11:588602. [PMID: 33193725 PMCID: PMC7596349 DOI: 10.3389/fgene.2020.588602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/21/2020] [Indexed: 12/14/2022] Open
Abstract
Transcription factors as multifaceted modulators of gene expression that play a central role in cell proliferation, differentiation, lineage commitment, and disease progression. They interact among themselves and create complex spatiotemporal gene regulatory networks that modulate hematopoiesis, cardiogenesis, and conditional differentiation of hematopoietic stem cells into cells of cardiovascular lineage. Additionally, bone marrow-derived stem cells potentially contribute to the cardiovascular cell population and have shown potential as a therapeutic approach to treat cardiovascular diseases. However, the underlying regulatory mechanisms are currently debatable. This review focuses on some key transcription factors and associated epigenetic modifications that modulate the maintenance and differentiation of hematopoietic stem cells and cardiac progenitor cells. In addition to this, we aim to summarize different potential clinical therapeutic approaches in cardiac regeneration therapy and recent discoveries in stem cell-based transplantation.
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Affiliation(s)
| | | | | | - Praphulla Chandra Shukla
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
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Lieberman A, Barrett R, Kim J, Zhang KL, Avery D, Monslow J, Kim H, Kim BJ, Puré E, Ryeom S. Deletion of Calcineurin Promotes a Protumorigenic Fibroblast Phenotype. Cancer Res 2019; 79:3928-3939. [PMID: 31189649 PMCID: PMC6679769 DOI: 10.1158/0008-5472.can-19-0056] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 04/25/2019] [Accepted: 06/05/2019] [Indexed: 01/05/2023]
Abstract
Fibroblast activation is a crucial step in tumor growth and metastatic progression. Activated fibroblasts remodel the extracellular matrix (ECM) in primary tumor and metastatic microenvironments, exerting both pro- and antitumorigenic effects. However, the intrinsic mechanisms that regulate the activation of fibroblasts are not well-defined. The signaling axis comprising the calcium-activated Ser/Thr phosphatase calcineurin (CN), and its downstream target nuclear factor of activated T cells, has been implicated in endothelial (EC) and immune cell activation, but its role in fibroblasts is not known. Here, we demonstrate that deletion of CN in fibroblasts in vitro altered fibroblast morphology and function consistent with an activated phenotype relative to wild-type fibroblasts. CN-null fibroblasts had a greater migratory capacity, increased collagen secretion and remodeling, and promoted more robust EC activation in vitro. ECM generated by CN-null fibroblasts contained more collagen with greater alignment of fibrillar collagen compared with wild-type fibroblast-derived matrix. These differences in matrix composition and organization imposed distinct changes in morphology and cytoskeletal architecture of both fibroblasts and tumor cells. Consistent with this in vitro phenotype, mice with stromal CN deletion had a greater incidence and larger lung metastases. Our data suggest that CN signaling contributes to the maintenance of fibroblast homeostasis and that loss of CN is sufficient to promote fibroblast activation. SIGNIFICANCE: Calcineurin signaling is a key pathway underlying fibroblast homeostasis that could be targeted to potentially prevent fibroblast activation in distant metastatic sites.
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Affiliation(s)
- Allyson Lieberman
- Department of Cancer Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - Richard Barrett
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - Jaewon Kim
- Department of Cancer Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kathy L Zhang
- Department of Cancer Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Diana Avery
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - James Monslow
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - Hyunsoo Kim
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Bang-Jin Kim
- Department of Cancer Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ellen Puré
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania.
| | - Sandra Ryeom
- Department of Cancer Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
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Bai J, Xu Y, Dieo Y, Sun G. Combined low-dose LiCl and LY294002 for the treatment of osteoporosis in ovariectomized rats. J Orthop Surg Res 2019; 14:177. [PMID: 31196133 PMCID: PMC6567919 DOI: 10.1186/s13018-019-1210-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 05/20/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND To provide a low-toxicity and high-efficacy clinical treatment for osteoporosis via a novel combination of LiCl and LY294002. METHODS The protein levels of p-AKT, AKT, p-GSK3β, GSK3β, β-catenin, p-β-catenin, and NFATC1 were measured in osteoblasts and osteoclasts by Western blot. ALP activity and TRACP activity were measured using the corresponding kit. The levels of BALP, PINP, CTX, and TRACP-5b were determined in accordance with the requirements of the ELISA kits. Microstructural analysis was performed on the left distal femur using microcomputed tomography. RESULTS Treatment with the combination of LiCl and LY294002 led to a markedly increased osteoblast activity but significantly decreased osteoclast differentiation and bone absorption capacity compared with the treatment with LiCl or LY294002 alone (P < 0.01). In serum, the low-dose combination of LiCl and LY294002 significantly enhanced BALP levels (P < 0.01) and significantly decreased PINP, TRACP-5b, and CTX levels (P < 0.01) compared with the application of either drug alone. CONCLUSIONS This study indicates that drug combinations directed at multiple targets could be used for osteoporosis treatment by promoting osteoblast proliferation and inhibiting differentiation with high efficiency.
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Affiliation(s)
- Jianhai Bai
- Department of Ophthalmology, Taizhou Central Hospital (Taizhou University Hospital), 999 Donghaidadao St, Jiaojiang District, Taizhou, 318000, Zhejiang Province, China
| | - Yier Xu
- The Fourth Affiliated Hospital of Nanchang University, 133 Guangchangnan St., Xihu District, Nanchang, China
| | - Yan Dieo
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China
| | - Guicai Sun
- The Fourth Affiliated Hospital of Nanchang University, 133 Guangchangnan St., Xihu District, Nanchang, China.
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RCANs regulate the convergent roles of NFATc1 in bone homeostasis. Sci Rep 2016; 6:38526. [PMID: 27917924 PMCID: PMC5137032 DOI: 10.1038/srep38526] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 11/11/2016] [Indexed: 01/04/2023] Open
Abstract
Activation of calcineurin-dependent nuclear factor of activated T cells c1 (NFATc1) is convergent for normal bone homeostasis. NFATc1 regulates both osteoclastogenesis and osteoblastogenesis. Here we investigated the roles of regulator of calcineurin (RCAN) genes in bone homeostasis. RCANs function as potent physiological inhibitors of calcineurin. Overexpression of RCANs in osteoclast precursor cells attenuated osteoclast differentiation, while their overexpression in osteoblasts enhanced osteoblast differentiation and function. Intriguingly, opposing effects of RCANs in both cell types were shown by blocking activation of the calcineurin-NFATc1 pathway. Moreover, the disruption of RCAN1 or RCAN2 in mice resulted in reduced bone mass, which is associated with strongly increased osteoclast function and mildly reduced osteoblast function. Taken together, RCANs play critical roles in bone homeostasis by regulating both osteoclastogenesis and osteoblastogenesis, and they serve as inhibitors for calcineurin-NFATc1 signaling both in vivo and in vitro.
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Chiu YH, Ritchlin CT. DC-STAMP: A Key Regulator in Osteoclast Differentiation. J Cell Physiol 2016; 231:2402-7. [PMID: 27018136 DOI: 10.1002/jcp.25389] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 03/24/2016] [Indexed: 01/09/2023]
Abstract
Osteoimmunology research is a new emerging research field that investigates the links between the bone and immune responses. Results from osteoimmunology studies suggest that bone is not only an essential component of the musculoskeletal system, but is also actively involved in immune regulation. Many important factors involved in immune regulation also participate in bone homeostasis. Bone homeostasis is achieved by a coordinated action between bone-synthesizing osteoblasts and bone-degrading osteoclasts. An imbalanced action between osteoblasts and osteoclasts often results in pathological bone diseases: osteoporosis is caused by an excessive osteoclast activity, whereas osteopetrosis results from an increased osteoblast activity. This review focuses on dendritic cell-specific transmembrane protein (DC-STAMP), an important protein currently considered as a master regulator of osteoclastogenesis. Of clinical relevance, the frequency of circulating DC-STAMP+ cells is elevated during the pathogenesis of psoriatic diseases. Intriguingly, recent results suggest that DC-STAMP also plays an imperative role in bone homeostasis by regulating the differentiation of both osteoclasts and osteoblasts. This article summarizes our current knowledge on DC-STAMP by focusing on its interacting proteins, its regulation on osteoclastogenesis-related genes, its possible involvement in immunoreceptor tyrosine-based inhibitory motif (ITIM)-mediated signaling cascade, and its potential of developing therapeutics for clinical applications. J. Cell. Physiol. 231: 2402-2407, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ya-Hui Chiu
- Division of Allergy, Immunology and Rheumatology, School of Medicine, University of Rochester, Rochester, New York
| | - Christopher T Ritchlin
- Division of Allergy, Immunology and Rheumatology, School of Medicine, University of Rochester, Rochester, New York
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Abstract
Ca(2+) release-activated Ca(2+) (CRAC) channels mediate a specific form of Ca(2+) influx called store-operated Ca(2+) entry (SOCE) that contributes to the function of many cell types. CRAC channels are composed of ORAI1 proteins located in the plasma membrane, which form its ion-conducting pore. ORAI1 channels are activated by stromal interaction molecule (STIM) 1 and STIM2 located in the endoplasmic reticulum. Loss- and gain-of-function gene mutations in ORAI1 and STIM1 in human patients cause distinct disease syndromes. CRAC channelopathy is caused by loss-of-function mutations in ORAI1 and STIM1 that abolish CRAC channel function and SOCE; it is characterized by severe combined immunodeficiency (SCID)-like disease, autoimmunity, muscular hypotonia, and ectodermal dysplasia, with defects in sweat gland function and dental enamel formation. The latter defect emphasizes an important role of CRAC channels in tooth development. By contrast, autosomal dominant gain-of-function mutations in ORAI1 and STIM1 result in constitutive CRAC channel activation, SOCE, and increased intracellular Ca(2+) levels that are associated with an overlapping spectrum of diseases, including nonsyndromic tubular aggregate myopathy (TAM) and York platelet and Stormorken syndromes. The latter two syndromes are defined, besides myopathy, by thrombocytopenia, thrombopathy, and bleeding diathesis. The fact that myopathy results from both loss- and gain-of-function mutations in ORAI1 and STIM1 highlights the importance of CRAC channels for Ca(2+) homeostasis in skeletal muscle function. The cellular dysfunction and clinical disease spectrum observed in mutant patients provide important information about the molecular regulation of ORAI1 and STIM1 proteins and the role of CRAC channels in human physiology.
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Affiliation(s)
- Rodrigo S Lacruz
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, New York
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Zanotti S, Canalis E. Activation of Nfatc2 in osteoblasts causes osteopenia. J Cell Physiol 2015; 230:1689-95. [PMID: 25573264 DOI: 10.1002/jcp.24928] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 01/07/2015] [Indexed: 01/08/2023]
Abstract
Nuclear factor of activated T-cells (Nfat) c1 to c4 are transcription factors that play an undisputable role in osteoclastogenesis. However, Nfat function in osteoblastic cells is controversial. Constitutive activation of Nfatc1 and c2 in osteoblasts suppresses cell function, although the study of Nfat in vivo has yielded conflicting results. To establish the consequences of Nfatc2 activation in osteoblasts, we generated transgenic mice where a 3.6 kb fragment of the collagen type I α1 promoter directs expression of a constitutively active Nfatc2 mutant (Col3.6-Nfatc2). The skeletal phenotype of Col3.6-Nfatc2 mice of both sexes and of sex-matched littermate controls was investigated by microcomputed tomography and histomorphometry. Col3.6- Nfatc2 mice were born at the expected Mendelian ratio and appeared normal. Nfatc2 expression was confirmed in parietal bones from 1 and 3 month old transgenic mice. One month old Col3.6-Nfatc2 female mice exhibited cancellous bone compartment osteopenia secondary to a 30% reduction in bone formation. In contrast, cancellous femoral bone volume and bone formation were not altered in male transgenics, whereas osteoblast number was higher, suggesting incomplete osteoblast maturation. Indices of bone resorption were not affected in either sex. At 3 months of age, the skeletal phenotype evolved; and Col3.6-Nfatc2 male mice exhibited vertebral osteopenia, whereas femoral cancellous bone was not affected in either sex. Nfatc2 activation in osteoblasts had no impact on cortical bone structure. Nfatc2 activation inhibited alkaline phosphatase activity and mineralized nodule formation in bone marrow stromal cell cultures. In conclusion, Nfatc2 activation in osteoblasts inhibits bone formation and causes cancellous bone osteopenia.
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Affiliation(s)
- Stefano Zanotti
- Departments of Orthopaedic Surgery and Medicine, UConn Health Center, Farmington, Connecticut
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Schreck C, Bock F, Grziwok S, Oostendorp RAJ, Istvánffy R. Regulation of hematopoiesis by activators and inhibitors of Wnt signaling from the niche. Ann N Y Acad Sci 2014; 1310:32-43. [PMID: 24611828 DOI: 10.1111/nyas.12384] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hematopoietic stem cells (HSCs) are a rare population of somatic stem cells that have the ability to regenerate the entire mature blood system in a hierarchical way for the duration of an adult life. Adult HSCs reside in the bone marrow niche. Different niche cell types and molecules regulate the balance of HSC dormancy and activation as well as HSC behavior in both normal and malignant hematopoiesis. Here, we describe the interplay of HSCs and their niche, in particular the involvement of the Wnt signaling pathway. Although the prevailing notion has been that malignant transformation of HSCs is the main cause of leukemia, evidence is mounting that disruption of niche regulation by transformed hematopoietic cells, which may overexpress Wnt signaling or intrinsic stromal defects in gene expression, is at least a collaborative factor in leukemogenesis. Thus, insights into the normal and altered functions of niche components will help to obtain a better understanding of normal and malignant hematopoiesis and how environmental factors affect these processes.
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Affiliation(s)
- Christina Schreck
- III. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany
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