This is the first study to our knowledge to report a novel mutation in the interferon regulatory factor 8 gene (IRF8G388S) associated with multiple idiopathic tooth root resorption, a form of periodontal disease. The IRF8G388S variant in the highly conserved C-terminal motif is predicted to alter the protein structure, likely impairing IRF8 function. Functional assays demonstrated that the IRF8G388S mutant promoted osteoclastogenesis and failed to inhibit NFATc1-dependent transcriptional activation when compared with IRF8WT control. Further, similar to subjects with heterozygous IRF8G388S mutation, Irf8+/– mice exhibited increased osteoclast activity in the mandibular alveolar bone surrounding molar teeth. Immunohistochemistry illustrated increased NFATc1 expression in the dentoalveolar region of Irf8–/– and Irf8+/– mice when compared with Irf8+/+ controls. Genomewide analyses revealed that IRF8 constitutively bound to regulatory regions of several thousand genes in osteoclast precursors, and genetic aberration of IRF8 significantly enhanced many osteoclast-specific transcripts. Collectively, this study delineates the critical role of IRF8 in defining osteoclast lineage and osteoclast transcriptional program, which may help in better understanding of various osteoclast-mediated disorders, including periodontal disease.
Bibliographical noteFunding Information:
Supported by grants AR066110 to BLF, DE028439 to VTM, start-up funds from University of Maryland School of Dentistry to VTM, and intramural funding to MJS from NIAMS/NIH and to KO from NICHD/NIH.
We thank the research subjects for participating in this study. We thank Eva Szymanski and Amy Hsu (NIAID/NIH) for assistance with Sanger sequencing. We thank Dr Steven Holland (NIAID/NIH) for intellectual input. We thank Dr Steve Bakke (University of Minnesota) for assistance in measuring TRAP+ cells and resorption pits. We thank Kristina Zaal (NIAMS/NIH) for assistance in imaging and slide scanning. We thank Gustavo Gutierrez-Cruz, Stefania Dell'Orso, and Faiza Naz (NIAMS/NIH) for assistance with RNA-seq data acquisition. We thank Dr Amitabh Das (University of Maryland) for assistance with macrophage RT-qPCR and Dr Xiaobei Wang (University of Maryland) for assistance with TRAP staining and immunohistochemistry. Supported by grants AR066110 to BLF, DE028439 to VTM, start-up funds from University of Maryland School of Dentistry to VTM, and intramural funding to MJS from NIAMS/NIH and to KO from NICHD/NIH. Data and materials availability: GEO accession number: GSE115497. Authors? roles: VTM and HY established functional assays and performed experiments. VTM, BLF, MB, KCM, MJS, and KO aided in experimental design and interpretation of the data. ALN obtained patient samples and provided clinical expertise. AC analyzed mouse bone microarchitecture. ST performed protein stability assay. VTM performed coimmunoprecipitation assay. SB, MB, and VTM performed bioinformatics analysis. ZD and BLF performed genetic analysis. VTM and BLF wrote the paper, supervised by MJS.
© 2019 American Society for Bone and Mineral Research
- DENTAL BIOLOGY