Springer Science and Business Media LLCActa Medica Okayama1873-96011742023Expression and function of CCN2-derived circRNAs in chondrocytes15011515ENSomaKatoDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesKazumiKawataDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesTakashiNishidaDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesTomomiMizukawaDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesMasaharuTakigawaAdvanced Research Center for Oral and Craniofacial Sciences, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical SciencesSeijiIidaDepartment of Oral Maxillofacial Reconstructive Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesSatoshiKubotaDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesCellular communication network factor 2 (CCN2) molecules promote endochondral ossification and articular cartilage regeneration, and circular RNAs (circRNAs), which arise from various genes and regulate gene expression by adsorbing miRNAs, are known to be synthesized from CCN2 in human vascular endothelial cells and other types of cells. However, in chondrocytes, not only the function but also the presence of CCN2-derived circRNA remains completely unknown. In the present study, we investigated the expression and function of CCN2-derived circRNAs in chondrocytes. Amplicons smaller than those from known CCN2-derived circRNAs were observed using RT-PCR analysis that could specifically amplify CCN2-derived circRNAs in human chondrocytic HCS-2/8 cells. The nucleotide sequences of the PCR products indicated novel circRNAs in the HCS-2/8 cells that were different from known CCN2-derived circRNAs. Moreover, the expression of several Ccn2-derived circRNAs in murine chondroblastic ATDC5 cells was confirmed and observed to change alongside chondrocytic differentiation. Next, one of these circRNAs was knocked down in HCS-2/8 cells to investigate the function of the human CCN2-derived circRNA. As a result, CCN2-derived circRNA knockdown significantly reduced the expression of aggrecan mRNA and proteoglycan synthesis. Our data suggest that CCN2-derived circRNAs are expressed in chondrocytes and play a role in chondrogenic differentiation.No potential conflict of interest relevant to this article was reported.Springer Science and Business Media LLCActa Medica Okayama1873-96011722023Do not overwork: cellular communication network factor 3 for life in cartilage353359ENSatoshiKubotaDepartment of Biochemistry and Molecular Dentistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical SciencesHarumiKawakiDepartment of Oral Biochemistry, Asahi University School of DentistryBernardPerbalInternational CCN SocietyMasaharuTakigawaAdvanced Research Center for Oral and Craniofacial Sciences, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical Sciences/Dental SchoolKazumiKawataDepartment of Biochemistry and Molecular Dentistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical SciencesTakakoHattoriDepartment of Biochemistry and Molecular Dentistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical SciencesTakashiNishidaDepartment of Biochemistry and Molecular Dentistry, Okayama University Faculty of Medicine, Dentistry and Pharmaceutical SciencesCellular communication network factor (CCN) 3, which is one of the founding members of the CCN family, displays diverse functions. However, this protein generally represses the proliferation of a variety of cells. Along with skeletal development, CCN3 is produced in cartilaginous anlagen, growth plate cartilage and epiphysial cartilage. Interestingly, CCN3 is drastically induced in the growth plates of mice lacking CCN2, which promotes endochondral ossification. Notably, chondrocytes in these mutant mice with elevated CCN3 production also suffer from impaired glycolysis and energy metabolism, suggesting a critical role of CCN3 in cartilage metabolism. Recently, CCN3 was found to be strongly induced by impaired glycolysis, and in our study, we located an enhancer that mediated CCN3 regulation via starvation. Subsequent investigations specified regulatory factor binding to the X-box 1 (RFX1) as a transcription factor mediating this CCN3 regulation. Impaired glycolysis is a serious problem, resulting in an energy shortage in cartilage without vasculature. CCN3 produced under such starved conditions restricts energy consumption by repressing cell proliferation, leading chondrocytes to quiescence and survival. This CCN3 regulatory system is indicated to play an important role in articular cartilage maintenance, as well as in skeletal development. Furthermore, CCN3 continues to regulate cartilage metabolism even during the aging process, probably utilizing this regulatory system. Altogether, CCN3 seems to prevent "overwork" by chondrocytes to ensure their sustainable life in cartilage by sensing energy metabolism. Similar roles are suspected to exist in relation to systemic metabolism, since CCN3 is found in the bloodstream.No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama1422-006723112022Molecular and Genetic Interactions between CCN2 and CCN3 behind Their Yin-Yang Collaboration5887ENSatoshiKubotaDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesKazumiKawataDepartment of Biochemistry and Molecular Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityTakakoHattoriDepartment of Biochemistry and Molecular Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityTakashiNishidaDepartment of Biochemistry and Molecular Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityCellular communication network factor (CCN) 2 and 3 are the members of the CCN family that conduct the harmonized development of a variety of tissues and organs under interaction with multiple biomolecules in the microenvironment. Despite their striking structural similarities, these two members show contrastive molecular functions as well as temporospatial emergence in living tissues. Typically, CCN2 promotes cell growth, whereas CCN3 restrains it. Where CCN2 is produced, CCN3 disappears. Nevertheless, these two proteins collaborate together to execute their mission in a yin-yang fashion. The apparent functional counteractions of CCN2 and CCN3 can be ascribed to their direct molecular interaction and interference over the cofactors that are shared by the two. Recent studies have revealed the mutual negative regulation systems between CCN2 and CCN3. Moreover, the simultaneous and bidirectional regulatory system of CCN2 and CCN3 is also being clarified. It is of particular note that these regulations were found to be closely associated with glycolysis, a fundamental procedure of energy metabolism. Here, the molecular interplay and metabolic gene regulation that enable the yin-yang collaboration of CCN2 and CCN3 typically found in cartilage development/regeneration and fibrosis are described.No potential conflict of interest relevant to this article was reported.Elsevier BVActa Medica Okayama8756-32821502021Odontoblast differentiation is regulated by an interplay between primary cilia and the canonical Wnt pathway116001ENKazumiKawataDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesKeishiNaritaDepartment of Anatomy and Cell Biology, University of Yamanashi Interdisciplinary Graduate School of Medicine and EngineeringAyakoWashioDivision of Endodontics and Restorative Dentistry, Department of Oral Functions, Kyushu Dental UniversityChiakiKitamuraDivision of Endodontics and Restorative Dentistry, Department of Oral Functions, Kyushu Dental UniversityTatsujiNishiharaDivision of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University,SatoshiKubotaDepartment of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesSenTakedaDepartment of Anatomy and Cell Biology, University of Yamanashi Interdisciplinary Graduate School of Medicine and EngineeringPrimary cilium is a protruding cellular organelle that has various physiological functions, especially in sensory reception. While an avalanche of reports on primary cilia have been published, the function of primary cilia in dental cells remains to be investigated. In this study, we focused on the function of primary cilia in dentin-producing odontoblasts. Odontoblasts, like most other cell types, possess primary cilia, which disappear upon the knockdown of intraflagellar transport-88. In cilia-depleted cells, the expression of dentin sialoprotein, an odontoblastic marker, was elevated, while the deposition of minerals was slowed. This was recapitulated by the activation of canonical Wnt pathway, also decreased the ratio of ciliated cells. In dental pulp cells, as they differentiated into odontoblasts, the ratio of ciliated cells was increased, whereas the canonical Wnt signaling activity was repressed. Our results collectively underscore the roles of primary cilia in regulating odontoblastic differentiation through canonical Wnt signaling. This study implies the existence of a feedback loop between primary cilia and the canonical Wnt pathway.No potential conflict of interest relevant to this article was reported.