transforming-growth-factor-beta and Osteosclerosis

The transforming growth factor β (TGF-β) and bone morphogenetic protein (BMP) signaling pathways play a pivotal role in bone development and skeletal health. More than 30 different types of skeletal dysplasia are now known to be caused by pathogenic variants in genes that belong to the TGF-β superfamily and/or regulate TGF-β/BMP bioavailability. This review describes the latest advances in skeletal dysplasia that is due to impaired TGF-β/BMP signaling and results in short stature (acromelic dysplasia and cardiospondylocarpofacial syndrome) or tall stature (Marfan syndrome). We thoroughly describe the clinical features of the patients, the underlying genetic findings, and the pathomolecular mechanisms leading to disease, which have been investigated mainly using patient-derived skin fibroblasts and mouse models. Although no pharmacological treatment is yet available for skeletal dysplasia due to impaired TGF-β/BMP signaling, in recent years advances in the use of drugs targeting TGF-β have been made, and we also discuss these advances.

Topics: Animals; Biological Availability; Bone Development; Mice; Osteochondrodysplasias; Osteosclerosis; Transforming Growth Factor beta

Transforming growth factor beta-activated kinase 1 (TAK1) is a highly conserved kinase protein encoded by MAP3K7, and activated by multiple extracellular stimuli, growth factors and cytokines. Heterozygous variants in MAP3K7 cause the cardiospondylocarpofacial syndrome (CSCFS) which is characterized by short stature, dysmorphic facial features, cardiac septal defects with valve dysplasia, and skeletal anomalies. CSCFS has been described in seven patients to date and its molecular pathogenesis is only partially understood. Here, the functional effects of the MAP3K7 c.737-7A > G variant, previously identified in a girl with CSCFS and additional soft connective tissue features, were explored. This splice variant generates an in-frame insertion of 2 amino acid residues in the kinase domain of TAK1. Computational analysis revealed that this in-frame insertion alters protein dynamics in the kinase activation loop responsible for TAK1 autophosphorylation after binding with its interactor TAB1. Co-immunoprecipitation studies demonstrate that the ectopic expression of TAK1-mutated protein impairs its ability to physically bind TAB1. In patient's fibroblasts, MAP3K7 c.737-7A > G variant results in reduced TAK1 autophosphorylation and dysregulation of the downstream TAK1-dependent signaling pathway. TAK1 loss-of-function is associated with an impaired TGFβ-mediated α-SMA cytoskeleton assembly and cell migration, and defective autophagy process. These findings contribute to our understanding of the molecular pathogenesis of CSCFS and might offer the rationale for the design of novel therapeutic targets.

Topics: Abnormalities, Multiple; Actins; Adaptor Proteins, Signal Transducing; Autophagy; Child; Cytoskeleton; Female; Fibroblasts; Hearing Loss, Bilateral; Humans; Loss of Function Mutation; MAP Kinase Kinase Kinases; Mitral Valve Insufficiency; Mutation; Osteosclerosis; Phosphorylation; Polymorphism, Single Nucleotide; Protein Binding; Signal Transduction; Transforming Growth Factor beta

Cardiospondylocarpofacial (CSCF) syndrome is characterized by growth retardation, dysmorphic facial features, brachydactyly with carpal-tarsal fusion and extensive posterior cervical vertebral synostosis, cardiac septal defects with valve dysplasia, and deafness with inner ear malformations. Whole-exome sequencing identified heterozygous MAP3K7 mutations in six distinct CSCF-affected individuals from four families and ranging in age from 5 to 37 years. MAP3K7 encodes transforming growth factor β (TGF-β)-activated kinase 1 (TAK1), which is involved in the mitogen-activated protein kinase (MAPK)-p38 signaling pathway. MAPK-p38 signaling was markedly altered when expression of non-canonical TGF-β-driven target genes was impaired. These findings support the loss of transcriptional control of the TGF-β-MAPK-p38 pathway in fibroblasts obtained from affected individuals. Surprisingly, although TAK1 is located at the crossroad of inflammation, immunity, and cancer, this study reports MAP3K7 mutations in a developmental disorder affecting mainly cartilage, bone, and heart.

Topics: Abnormalities, Multiple; Adolescent; Adult; Carpal Bones; Cervical Vertebrae; Child; Child, Preschool; Female; Fibroblasts; Gene Expression Regulation; Hearing Loss, Bilateral; Hearing Loss, Conductive; Heterozygote; Humans; Interleukin-1beta; Male; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Mitral Valve Insufficiency; Mutation; Osteosclerosis; p38 Mitogen-Activated Protein Kinases; Syndrome; Tarsal Bones; Transforming Growth Factor beta; Young Adult

Metastasis is the rapid proliferation of cancer cells (secondary tumour) at a specific place, generally leading to death. This occurs at anatomical parts providing the necessary environment for vascularity, oxygen and food to hide their actions and trigger the rapid growth of cancer. Prostate and breast cancers, for example, use bone marrow for their proliferation. Bone-supporting cancer cells thus adapt to the environment, mimicking the behaviour of genetic and molecular bone cells. Evidence of this has been given in Cecchini et al. (2005, EAU Update Ser. 3:214-226), providing arguments such as how cancer cell growth is so active during bone reabsorption. This paper simulates metastasis activation in bone marrow. A mathematical model has been developed involving the activation of molecules from bone tissue cells, which are necessary for cancer to proliferate. Here, we simulate two forms of secondary tumour growth depending on the type of metastasis: osteosclerosis and osteolysis.

Topics: Biomedical Engineering; Bone Marrow Neoplasms; Bone Neoplasms; Bone Remodeling; Cell Differentiation; Cell Proliferation; Computer Simulation; Humans; Mathematical Concepts; Models, Biological; Neoplasm Metastasis; Osteolysis; Osteosclerosis; Parathyroid Hormone-Related Protein; Somatomedins; Transforming Growth Factor beta

Hepatitis C-associated osteosclerosis (HCAO) is a rare syndrome characterized by severe, acquired, generalized osteosclerosis and hyperostosis in adults who are infected with the hepatitis C virus. However, the detail of the pathogenesis of HCAO is still unknown. We examined the effects of serum of the HCAO patient on the proliferation, alkaline phosphatase (ALP) activity and transforming growth factor (TGF)-beta-Smad signaling in mouse osteoblastic cells. The patient was compatible with HCAO, characterized by high bone mass, bone thickening and bone pain with normal lamelar bone. The serum from the HCAO patient increased the levels of TGF-beta and Smad3 expression in osteoblastic MC3T3-E1 cells, compared with the control subject. Moreover, the serum from the HCAO patient significantly augmented TGF-beta-induced transcriptional activity with luciferase assay using 3TP-Lux with a Smad3-specific responsive element. In addition, the serum from the HCAO patient significantly stimulated the MTT intensity, the level of proliferating cell nuclear antigen expression, a proliferation marker, and ALP activity in MC3T3-E1 cells, compared with that from the control subject. In conclusion, the present study indicated that the serum from the HCAO patient stimulated TGF-beta-Smad signaling, as well as the proliferation and ALP activity in osteoblastic cells. Some soluble factors other than parathyroid hormone might be related to the pathogenesis of HCAO.

Topics: 3T3 Cells; Absorptiometry, Photon; Alkaline Phosphatase; Animals; Bone and Bones; Bone Development; Cell Division; Diphosphonates; Gene Expression Regulation; Hepatitis C; Humans; Male; Mice; Middle Aged; Mitochondria; Osteoblasts; Osteosclerosis; Pamidronate; Transfection; Transforming Growth Factor beta

All mice harboring the X-linked Gata1low mutation in a predominantly CD1 background are born anemic and thrombocytopenic. They recover from anemia at 1 month of age but remain thrombocytopenic all their life and develop myelofibrosis, a syndrome similar to human idiopathic myelofibrosis, at 12 months. The effects of the genetic background on the myelofibrosis developed by Gata1low mice was assessed by introducing the mutation, by standard genetic approaches, in the C57BL/6 and DBA/2 backgrounds and by analyzing the phenotype of the different mutants at 12 to 13 (by histology) and 16 to 20 (by cytofluorimetry) months of age. Although all the Gata1low mice developed fibrosis at 12 to 13 months, variegations were observed in the severity of the phenotype expressed by mutants of different backgrounds. In C57BL/6 mice, the mutation was no longer inherited in a Mendelian fashion, and fibrosis was associated with massive osteosclerosis. Instead, DBA/2 mutants, although severely anemic, expressed limited fibrosis and osteosclerosis and did not present tear-drop poikilocytes in blood or extramedullary hemopoiesis in liver up to 20 months of age. We propose that the variegation in myelofibrosis expressed by Gata1low mutants of different strains might represent a model to study the variability of the clinical picture of the human disease.

Topics: Aging; Animals; Antigens, CD; Ataxin-1; Ataxins; Biomarkers; Blood Group Antigens; Erythroblasts; Femur; GATA1 Transcription Factor; Hematopoiesis; Mice; Mice, Inbred Strains; Mice, Transgenic; Mutation; Nerve Tissue Proteins; Nuclear Proteins; Osteosclerosis; Phenotype; Spleen; Stem Cells; Transforming Growth Factor beta

The aim of this study is to investigate the mechanism of osteosclerosis in IMF in relation to OPG derangement.. Plasma OPG level was assayed by OPG ELISA in 19 patients with IMF, 15 patients with other myeloproliferative disorders (MPDs), and 12 normal volunteers as controls and correlated with the degree of osteosclerosis. Furthermore, the level of OPG mRNA, in the cultured bone marrow stromal (BMS) cells of patients with IMF and anemia patients used as controls, in the presence or absence of TGF-beta1, was studied by real-time RT-PCR.. The present study showed that blood OPG level was significantly elevated in patients with IMF as compared to patients with other MPDs (p < 0.01) or normal volunteer controls (p < 0.05), and there was no significant difference in the level between patients with MPDs and controls. In addition, there was a positive correlation (r=0.67, p=0.04) between plasma OPG levels and the degree of osteosclerosis. There was no difference in the OPG mRNA in patients with IMF as compared with controls even on TGF-beta1 stimulation.. These results suggest that osteosclerosis in IMF may be related to overproduction of OPG and enhanced level of OPG is not due to the effect of TGF-beta1 on the BMS cells. It could be due to the effect of TGF-beta1 or other growth factors on cells other than BMS cells such as the osteoblasts.

Topics: Bone Marrow Cells; Case-Control Studies; Cells, Cultured; Glycoproteins; Humans; Myeloproliferative Disorders; Osteoprotegerin; Osteosclerosis; Primary Myelofibrosis; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; RNA, Messenger; Stromal Cells; Transforming Growth Factor beta; Transforming Growth Factor beta1

Myelofibrosis and osteosclerosis are prominent features arising in mice overexpressing thrombopoietin (TPO). The pivotal role of transforming growth factor beta 1 (TGF-beta 1) in the pathogenesis of myelofibrosis has been documented, but the mechanisms mediating osteosclerosis remain unclear. Here, we used mice deficient in osteoprotegerin (OPG), a secreted inhibitor of bone resorption, to determine whether osteosclerosis occurs through a deregulation of osteoclastogenesis. Marrow cells from opg-deficient mice (opg(-/-)) or wild-type (WT) littermates were infected with a retrovirus encoding TPO and engrafted into an opg(-/-) or WT background for long-term reconstitution. The 4 combinations of graft/host (WT/WT, opg(-/-)/opg(-/-), opg(-/-)/WT, and WT/opg(-/-)) were studied. Elevation of TPO and TGF-beta 1 levels in plasma was similar in the 4 experimental groups and all the mice developed a similar myeloproliferative syndrome associated with severe myelofibrosis. Osteosclerosis developed in WT hosts engrafted with WT or opg(-/-) hematopoietic cells and was associated with increased OPG levels in plasma and decreased osteoclastogenesis. In contrast, opg(-/-) hosts exhibited an osteoporotic phenotype and a growth of bone trabeculae was rarely seen. These findings suggest that osteosclerosis in mice with TPO overexpression occurs predominantly via an up-regulation of OPG in host stromal cells leading to disruption of osteoclastogenesis.

Topics: Animals; Bone and Bones; Bone Marrow Transplantation; Cells, Cultured; Disease Models, Animal; Gene Expression Regulation; Genetic Vectors; Glycoproteins; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myeloproliferative Disorders; Osteoclasts; Osteoporosis; Osteoprotegerin; Osteosclerosis; Primary Myelofibrosis; Radiation Chimera; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Recombinant Fusion Proteins; Retroviridae; Thrombopoietin; Transduction, Genetic; Transforming Growth Factor beta; Transforming Growth Factor beta1

The TGF-betas are multifunctional proteins whose activities are believed to be controlled by interaction with the latent TGF-beta binding proteins (LTBPs). In spite of substantial effort, the precise in vivo significance of this interaction remains unknown. To examine the role of the Ltbp-3, we made an Ltbp-3-null mutation in the mouse by gene targeting. Homozygous mutant animals develop cranio-facial malformations by day 10. At 2 mo, there is a pronounced rounding of the cranial vault, extension of the mandible beyond the maxilla, and kyphosis. Histological examination of the skulls from null animals revealed ossification of the synchondroses within 2 wk of birth, in contrast to the wild-type synchondroses, which never ossify. Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis. The pathological changes of the Ltbp-3-null mice are consistent with perturbed TGF-beta signaling in the skull and long bones. These observations give support to the notion that LTBP-3 is important for the control of TGF-beta action. Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-beta bioavailability.

Topics: Adaptor Proteins, Signal Transducing; Animals; Bone and Bones; Bone Remodeling; Carrier Proteins; Craniofacial Abnormalities; Gene Deletion; Gene Targeting; In Situ Hybridization; Latent TGF-beta Binding Proteins; Mice; Mice, Knockout; Osteoarthritis; Osteosclerosis; RNA, Messenger; Skull; Transforming Growth Factor beta

We have previously shown that mice induced to overexpress thrombopoietin (TPO) by retroviral-mediated gene transfer into bone marrow (BM) cells develop myelofibrosis and osteosclerosis. It was speculated that these effects were secondary to TPO, resulting from high levels of megakaryocytes and platelets. Also, it was proposed that these mice represent a model for myelofibrosis and osteosclerosis. In this report, we show that levels of both transforming growth factor-beta 1 and platelet-derived growth factor are increased twofold to fivefold in the platelet-poor plasma of TPO overexpressing mice compared with control mice. These data suggest that the increased megakaryocytes produce elevated levels of these cytokines that lead to the pathogenesis of disease. Further, we retransplanted TPO overexpressing mice, at 40 to 42 weeks after primary transplantation, with normal BM cells. After the secondary transplantation, megakaryocytes and platelets returned to normal levels and the myelofibrosis and osteosclerosis were completely corrected. These data extend our initial studies of the effects of overexpression of TPO and show the potential use of this model to explore the underlying cause of myelofibrosis and osteosclerosis and potential treatments for these diseases.

Topics: Animals; Blood Platelets; Bone and Bones; Bone Marrow Transplantation; Cells, Cultured; Disease Models, Animal; Female; Gene Expression Regulation, Viral; Gene Transfer Techniques; Genetic Vectors; Hematopoietic Stem Cell Transplantation; Hematopoietic Stem Cells; Male; Megakaryocytes; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Osteosclerosis; Platelet-Derived Growth Factor; Primary Myelofibrosis; Proviruses; Radiation Chimera; Recombinant Fusion Proteins; Repetitive Sequences, Nucleic Acid; Retroviridae; Spleen; Thrombopoietin; Transfection; Transforming Growth Factor beta