Altered cytoskeletal organization characterized lethal but not surviving Brtl+/- mice: insight on phenotypic variability in osteogenesis imperfecta.
Osteogenesis imperfecta (OI) is a heritable bone disease with dominant and recessive transmission. It is characterized by a wide spectrum of clinical outcomes ranging from very mild to lethal in the perinatal period. The intra- and inter-familiar OI phenotypic variability in the presence of an identical molecular defect is still puzzling to the research field. We used the OI murine model Brtl(+/-) to investigate the molecular basis of OI phenotypic variability. Brtl(+/-) resembles classical dominant OI and shows either a moderately severe or a lethal outcome associated with the same Gly349Cys substitution in the α1 chain of type I collagen. A systems biology approach was used. We took advantage of proteomic pathway analysis to functionally link proteins differentially expressed in bone and skin of Brtl(+/-) mice with different outcomes to define possible phenotype modulators. The skin/bone and bone/skin hybrid networks highlighted three focal proteins: vimentin, stathmin and cofilin-1, belonging to or involved in cytoskeletal organization. Abnormal cytoskeleton was indeed demonstrated by immunohistochemistry to occur only in tissues from Brtl(+/-) lethal mice. The aberrant cytoskeleton affected osteoblast proliferation, collagen deposition, integrin and TGF-β signaling with impairment of bone structural properties. Finally, aberrant cytoskeletal assembly was detected in fibroblasts obtained from lethal, but not from non-lethal, OI patients carrying an identical glycine substitution. Our data demonstrated that compromised cytoskeletal assembly impaired both cell signaling and cellular trafficking in mutant lethal mice, altering bone properties. These results point to the cytoskeleton as a phenotypic modulator and potential novel target for OI treatment.
Functional Proteomics Laboratory, Department of Life Sciences, University of Siena, Siena, Italy.
Laura
L
Bianchi
Functional Proteomics Laboratory, Department of Life Sciences, University of Siena, Siena, Italy.
Assunta
A
Gagliardi
Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy.
Silvia
S
Maruelli
Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy.
Roberta
R
Besio
Functional Proteomics Laboratory, Department of Life Sciences, University of Siena, Siena, Italy.
Claudia
C
Landi
Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy.
Roberta
R
Gioia
Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.
Kenneth M
KM
Kozloff
Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.
Basma M
BM
Khoury
Center for Medical Genetics, Ghent University, Ghent, Belgium and.
Paul J
PJ
Coucke
Center for Medical Genetics, Ghent University, Ghent, Belgium and.
Sofie
S
Symoens
Bone and Extracellular Matrix Branch, NICHD, National Institute of Health, Bethesda, MD, USA.
Joan C
JC
Marini
Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy.
Antonio
A
Rossi
Functional Proteomics Laboratory, Department of Life Sciences, University of Siena, Siena, Italy.
Luca
L
Bini
Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy, aforlino@unipv.it.
Antonella
A
Forlino
D048948:14-3-3 Proteins / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism / Q000473:pathology; D051338:Cofilin 1 / Q000378:metabolism; D024042:Collagen Type I / Q000235:genetics; D000090602:Collagen Type I, alpha 1 Chain; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000378:metabolism; D005804:Genes, Lethal; D006801:Humans; D016023:Integrins / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D010013:Osteogenesis Imperfecta / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D014746:Vimentin / Q000378:metabolism
D048948:14-3-3 Proteins; C495811:Cfl1 protein, mouse; D051338:Cofilin 1; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D003598:Cytoskeletal Proteins; D016023:Integrins; C499130:Sfn protein, mouse; D014746:Vimentin