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Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice

Osteogenesis Imperfecta (OI) is a human syndrome characterized by exquisitely fragile bones due to osteoporosis. The majority of autosomal dominant OI cases result from point or splice site mutations in the type I collagen genes, which are thought to lead to aberrant osteoid within developing bones....

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Autores principales: Choi, Jae Won, Sutor, Shari L., Lindquist, Lonn, Evans, Glenda L., Madden, Benjamin J., Bergen, H. Robert, Hefferan, Theresa E., Yaszemski, Michael J., Bram, Richard J.
Formato: Texto
Lenguaje:English
Publicado: Public Library of Science 2009
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2777385/
https://www.ncbi.nlm.nih.gov/pubmed/19997487
http://dx.doi.org/10.1371/journal.pgen.1000750
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author Choi, Jae Won
Sutor, Shari L.
Lindquist, Lonn
Evans, Glenda L.
Madden, Benjamin J.
Bergen, H. Robert
Hefferan, Theresa E.
Yaszemski, Michael J.
Bram, Richard J.
author_facet Choi, Jae Won
Sutor, Shari L.
Lindquist, Lonn
Evans, Glenda L.
Madden, Benjamin J.
Bergen, H. Robert
Hefferan, Theresa E.
Yaszemski, Michael J.
Bram, Richard J.
author_sort Choi, Jae Won
collection PubMed
description Osteogenesis Imperfecta (OI) is a human syndrome characterized by exquisitely fragile bones due to osteoporosis. The majority of autosomal dominant OI cases result from point or splice site mutations in the type I collagen genes, which are thought to lead to aberrant osteoid within developing bones. OI also occurs in humans with homozygous mutations in Prolyl-3-Hydroxylase-1 (LEPRE1). Although P3H1 is known to hydroxylate a single residue (pro-986) in type I collagen chains, it is unclear how this modification acts to facilitate collagen fibril formation. P3H1 exists in a complex with CRTAP and the peptidyl-prolyl isomerase cyclophilin B (CypB), encoded by the Ppib gene. Mutations in CRTAP cause OI in mice and humans, through an unknown mechanism, while the role of CypB in this complex has been a complete mystery. To study the role of mammalian CypB, we generated mice lacking this protein. Early in life, Ppib-/- mice developed kyphosis and severe osteoporosis. Collagen fibrils in Ppib-/- mice had abnormal morphology, further consistent with an OI phenotype. In vitro studies revealed that in CypB–deficient fibroblasts, procollagen did not localize properly to the golgi. We found that levels of P3H1 were substantially reduced in Ppib-/- cells, while CRTAP was unaffected by loss of CypB. Conversely, knockdown of either P3H1 or CRTAP did not affect cellular levels of CypB, but prevented its interaction with collagen in vitro. Furthermore, knockdown of CRTAP also caused depletion of cellular P3H1. Consistent with these changes, post translational prolyl-3-hydroxylation of type I collagen by P3H1 was essentially absent in CypB–deficient cells and tissues from CypB–knockout mice. These data provide significant new mechanistic insight into the pathophysiology of OI and reveal how the members of the P3H1/CRTAP/CypB complex interact to direct proper formation of collagen and bone.
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spelling pubmed-27773852009-12-08 Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice Choi, Jae Won Sutor, Shari L. Lindquist, Lonn Evans, Glenda L. Madden, Benjamin J. Bergen, H. Robert Hefferan, Theresa E. Yaszemski, Michael J. Bram, Richard J. PLoS Genet Research Article Osteogenesis Imperfecta (OI) is a human syndrome characterized by exquisitely fragile bones due to osteoporosis. The majority of autosomal dominant OI cases result from point or splice site mutations in the type I collagen genes, which are thought to lead to aberrant osteoid within developing bones. OI also occurs in humans with homozygous mutations in Prolyl-3-Hydroxylase-1 (LEPRE1). Although P3H1 is known to hydroxylate a single residue (pro-986) in type I collagen chains, it is unclear how this modification acts to facilitate collagen fibril formation. P3H1 exists in a complex with CRTAP and the peptidyl-prolyl isomerase cyclophilin B (CypB), encoded by the Ppib gene. Mutations in CRTAP cause OI in mice and humans, through an unknown mechanism, while the role of CypB in this complex has been a complete mystery. To study the role of mammalian CypB, we generated mice lacking this protein. Early in life, Ppib-/- mice developed kyphosis and severe osteoporosis. Collagen fibrils in Ppib-/- mice had abnormal morphology, further consistent with an OI phenotype. In vitro studies revealed that in CypB–deficient fibroblasts, procollagen did not localize properly to the golgi. We found that levels of P3H1 were substantially reduced in Ppib-/- cells, while CRTAP was unaffected by loss of CypB. Conversely, knockdown of either P3H1 or CRTAP did not affect cellular levels of CypB, but prevented its interaction with collagen in vitro. Furthermore, knockdown of CRTAP also caused depletion of cellular P3H1. Consistent with these changes, post translational prolyl-3-hydroxylation of type I collagen by P3H1 was essentially absent in CypB–deficient cells and tissues from CypB–knockout mice. These data provide significant new mechanistic insight into the pathophysiology of OI and reveal how the members of the P3H1/CRTAP/CypB complex interact to direct proper formation of collagen and bone. Public Library of Science 2009-12-04 /pmc/articles/PMC2777385/ /pubmed/19997487 http://dx.doi.org/10.1371/journal.pgen.1000750 Text en Choi et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Choi, Jae Won
Sutor, Shari L.
Lindquist, Lonn
Evans, Glenda L.
Madden, Benjamin J.
Bergen, H. Robert
Hefferan, Theresa E.
Yaszemski, Michael J.
Bram, Richard J.
Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice
title Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice
title_full Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice
title_fullStr Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice
title_full_unstemmed Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice
title_short Severe Osteogenesis Imperfecta in Cyclophilin B–Deficient Mice
title_sort severe osteogenesis imperfecta in cyclophilin b–deficient mice
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2777385/
https://www.ncbi.nlm.nih.gov/pubmed/19997487
http://dx.doi.org/10.1371/journal.pgen.1000750
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