Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia

Abstract Craniometaphyseal dysplasia (CMD), a rare craniotubular disorder, occurs in an autosomal dominant (AD) or autosomal recessive (AR) form. CMD is characterized by hyperostosis of craniofacial bones and metaphyseal flaring of long bones. Many patients with CMD suffer from neurological symptoms...

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Main Authors: Yasuyuki Fujii, Iichiro Okabe, Ayano Hatori, Shyam Kishor Sah, Jitendra Kanaujiya, Melanie Fisher, Rachael Norris, Mark Terasaki, Ernst J. Reichenberger, I-Ping Chen
Format: Article
Language:English
Published: Nature Publishing Group 2025-01-01
Series:Bone Research
Online Access:https://doi.org/10.1038/s41413-024-00383-z
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author Yasuyuki Fujii
Iichiro Okabe
Ayano Hatori
Shyam Kishor Sah
Jitendra Kanaujiya
Melanie Fisher
Rachael Norris
Mark Terasaki
Ernst J. Reichenberger
I-Ping Chen
author_facet Yasuyuki Fujii
Iichiro Okabe
Ayano Hatori
Shyam Kishor Sah
Jitendra Kanaujiya
Melanie Fisher
Rachael Norris
Mark Terasaki
Ernst J. Reichenberger
I-Ping Chen
author_sort Yasuyuki Fujii
collection DOAJ
description Abstract Craniometaphyseal dysplasia (CMD), a rare craniotubular disorder, occurs in an autosomal dominant (AD) or autosomal recessive (AR) form. CMD is characterized by hyperostosis of craniofacial bones and metaphyseal flaring of long bones. Many patients with CMD suffer from neurological symptoms. The pathogenesis of CMD is not fully understood. Treatment is limited to craniofacial surgery. Here, we report a knock in (KI) mouse model for AR CMD carrying a Cx43R239Q mutation. Cx43 KI/KI mice replicate typical features of AR CMD, including thickening of craniofacial bones, club-shaped femurs, and widened diaphyseal cortical bones. Female Cx43 KI/KI mice display remarkably more bone overgrowth than male Cx43 KI/KI mice as they age. In contrast to Cx43 +/+ littermates, Cx43 KI/KI mice exhibit periosteal bone deposition and increased osteoclast (OC) numbers in the endosteum of long bones. Although formation of resting OCs in Cx43 +/+ and Cx43 KI/KI mice is comparable, the actively resorbing Cx43 KI/KI OCs have reduced resorption on bone chips. Cx43 KI/KI mice display reduced osteocyte dendrites. RNA from Cx43 KI/KI femoral cortical bones show reduced expression levels of Sost, Tnf-α, IL-1β, Esr1, Esr2, and a lower Rankl/Opg ratio. Moreover, the Cx43R239Q mutation results in altered spatial expression of Cx43 protein and mild reduction of gap junction and hemichannel activity. The distinct phenotype seen in Cx43 KI/KI mice but not in Cx43 ablation models suggests that Cx43 loss-of-function is unlikely the main cause of AR CMD. Additional studies are required to investigate new roles of CMD-mutant Cx43.
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spelling doaj-art-5f44f023487e41b5afd76f7119ecb88f2025-01-26T12:19:46ZengNature Publishing GroupBone Research2095-62312025-01-0113111410.1038/s41413-024-00383-zSkeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasiaYasuyuki Fujii0Iichiro Okabe1Ayano Hatori2Shyam Kishor Sah3Jitendra Kanaujiya4Melanie Fisher5Rachael Norris6Mark Terasaki7Ernst J. Reichenberger8I-Ping Chen9Department of Endodontology, School of Dental Medicine, University of Connecticut HealthDepartment of Endodontology, School of Dental Medicine, University of Connecticut HealthDepartment of Endodontology, School of Dental Medicine, University of Connecticut HealthDepartment of Endodontology, School of Dental Medicine, University of Connecticut HealthDepartment of Cell Biology, University of Connecticut HealthDepartment of Cell Biology, University of Connecticut HealthDepartment of Cell Biology, University of Connecticut HealthDepartment of Cell Biology, University of Connecticut HealthCenter for Regenerative Medicine and Skeletal Development, School of Dental Medicine, University of Connecticut HealthDepartment of Endodontology, School of Dental Medicine, University of Connecticut HealthAbstract Craniometaphyseal dysplasia (CMD), a rare craniotubular disorder, occurs in an autosomal dominant (AD) or autosomal recessive (AR) form. CMD is characterized by hyperostosis of craniofacial bones and metaphyseal flaring of long bones. Many patients with CMD suffer from neurological symptoms. The pathogenesis of CMD is not fully understood. Treatment is limited to craniofacial surgery. Here, we report a knock in (KI) mouse model for AR CMD carrying a Cx43R239Q mutation. Cx43 KI/KI mice replicate typical features of AR CMD, including thickening of craniofacial bones, club-shaped femurs, and widened diaphyseal cortical bones. Female Cx43 KI/KI mice display remarkably more bone overgrowth than male Cx43 KI/KI mice as they age. In contrast to Cx43 +/+ littermates, Cx43 KI/KI mice exhibit periosteal bone deposition and increased osteoclast (OC) numbers in the endosteum of long bones. Although formation of resting OCs in Cx43 +/+ and Cx43 KI/KI mice is comparable, the actively resorbing Cx43 KI/KI OCs have reduced resorption on bone chips. Cx43 KI/KI mice display reduced osteocyte dendrites. RNA from Cx43 KI/KI femoral cortical bones show reduced expression levels of Sost, Tnf-α, IL-1β, Esr1, Esr2, and a lower Rankl/Opg ratio. Moreover, the Cx43R239Q mutation results in altered spatial expression of Cx43 protein and mild reduction of gap junction and hemichannel activity. The distinct phenotype seen in Cx43 KI/KI mice but not in Cx43 ablation models suggests that Cx43 loss-of-function is unlikely the main cause of AR CMD. Additional studies are required to investigate new roles of CMD-mutant Cx43.https://doi.org/10.1038/s41413-024-00383-z
spellingShingle Yasuyuki Fujii
Iichiro Okabe
Ayano Hatori
Shyam Kishor Sah
Jitendra Kanaujiya
Melanie Fisher
Rachael Norris
Mark Terasaki
Ernst J. Reichenberger
I-Ping Chen
Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
Bone Research
title Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
title_full Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
title_fullStr Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
title_full_unstemmed Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
title_short Skeletal abnormalities caused by a Connexin43R239Q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
title_sort skeletal abnormalities caused by a connexin43r239q mutation in a mouse model for autosomal recessive craniometaphyseal dysplasia
url https://doi.org/10.1038/s41413-024-00383-z
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