TY - JOUR
T1 - Osteoblast-specific expression of the fibrous dysplasia (FD)-causing mutation Gsα(R201C) produces a high bone mass phenotype but does not reproduce FD in the mouse
AU - Remoli, Cristina
AU - Michienzi, Stefano
AU - Sacchetti, Benedetto
AU - Consiglio, Alberto Di
AU - Cersosimo, Stefania
AU - Spica, Emanuela
AU - Robey, Pamela G
AU - Holmbeck, Kenn
AU - Cumano, Ana
AU - Boyde, Alan
AU - Davis, Graham
AU - Saggio, Isabella
AU - Riminucci, Mara
AU - Bianco, Paolo
N1 - © 2014 American Society for Bone and Mineral Research.
PY - 2015/6/1
Y1 - 2015/6/1
N2 - We recently reported the generation and initial characterization of the first direct model of human fibrous dysplasia (FD; OMIM #174800), obtained through the constitutive systemic expression of one of the disease-causing mutations, Gsα(R201C) , in the mouse. To define the specific pathogenetic role(s) of individual cell types within the stromal/osteogenic system in FD, we generated mice expressing Gsα(R201C) selectively in mature osteoblasts using the 2.3kb Col1a1 promoter. We show here that this results in a striking high bone mass phenotype but not in a mimicry of human FD. The high bone mass phenotype involves specifically a deforming excess of cortical bone and prolonged and ectopic cortical bone remodeling. Expression of genes characteristic of late stages of bone cell differentiation/maturation is profoundly altered as a result of expression of Gsα(R201C) in osteoblasts, and expression of the Wnt inhibitor Sost is reduced. Although high bone mass is, in fact, a feature of some types/stages of FD lesions in humans, it is marrow fibrosis, localized loss of adipocytes and hematopoietic tissue, osteomalacia, and osteolytic changes that together represent the characteristic pathological profile of FD, as well as the sources of specific morbidity. None of these features are reproduced in mice with osteoblast-specific expression of Gsα(R201C) . We further show that hematopoietic progenitor/stem cells, as well as more mature cell compartments, and adipocyte development are normal in these mice. These data demonstrate that effects of Gsα mutations underpinning FD-defining tissue changes and morbidity do not reflect the effects of the mutations on osteoblasts proper.
AB - We recently reported the generation and initial characterization of the first direct model of human fibrous dysplasia (FD; OMIM #174800), obtained through the constitutive systemic expression of one of the disease-causing mutations, Gsα(R201C) , in the mouse. To define the specific pathogenetic role(s) of individual cell types within the stromal/osteogenic system in FD, we generated mice expressing Gsα(R201C) selectively in mature osteoblasts using the 2.3kb Col1a1 promoter. We show here that this results in a striking high bone mass phenotype but not in a mimicry of human FD. The high bone mass phenotype involves specifically a deforming excess of cortical bone and prolonged and ectopic cortical bone remodeling. Expression of genes characteristic of late stages of bone cell differentiation/maturation is profoundly altered as a result of expression of Gsα(R201C) in osteoblasts, and expression of the Wnt inhibitor Sost is reduced. Although high bone mass is, in fact, a feature of some types/stages of FD lesions in humans, it is marrow fibrosis, localized loss of adipocytes and hematopoietic tissue, osteomalacia, and osteolytic changes that together represent the characteristic pathological profile of FD, as well as the sources of specific morbidity. None of these features are reproduced in mice with osteoblast-specific expression of Gsα(R201C) . We further show that hematopoietic progenitor/stem cells, as well as more mature cell compartments, and adipocyte development are normal in these mice. These data demonstrate that effects of Gsα mutations underpinning FD-defining tissue changes and morbidity do not reflect the effects of the mutations on osteoblasts proper.
KW - Amino Acid Substitution
KW - Animals
KW - Bone and Bones/metabolism
KW - Chromogranins
KW - Disease Models, Animal
KW - Fibrous Dysplasia of Bone/genetics
KW - GTP-Binding Protein alpha Subunits, Gs/genetics
KW - Gene Expression Regulation
KW - Humans
KW - Mice
KW - Mice, Transgenic
KW - Mutation, Missense
KW - Organ Size
KW - Osteoblasts/metabolism
U2 - 10.1002/jbmr.2425
DO - 10.1002/jbmr.2425
M3 - Journal article
C2 - 25487351
SN - 0884-0431
VL - 30
SP - 1030
EP - 1043
JO - Journal of Bone and Mineral Research
JF - Journal of Bone and Mineral Research
IS - 6
ER -