Background: SATB2-associated syndrome (SAS) is a multisystem disorder caused by mutation of humanSATB2gene. Tooth agenesis is one of the most common phenotypes observed in SAS. Our study aimed at identifying novel variant of SATB2 in a patient with SAS, and to investigate the cellular and molecular mechanism of tooth agenesis caused bySATB2mutation.Methods: We applied whole exome sequencing (WES) to identify the novel mutation ofSATB2in a Chinese patient with SAS. Construction and overexpression of wild-type and the mutant vector was performed, followed by functional analysis including flow cytometry assay, fluorescent immunocytochemistry, western blot, quantitative real-time PCR and Alizarin Red S staining to investigate its impact on hDPSCs and the underlying mechanisms.Results: As a result, we identified a novel frameshift mutation ofSATB2(c. 376_378delinsTT) in a patient with SAS exhibiting tooth agenesis. Human DPSCs transfected with mutant SATB2 showed decreased cell proliferation and odontogenic differentiation capacity compared with hDPSCs transfected with wild-type SATB2 plasmid. Mechanistically, mutant SATB2 failed to translocate into nucleus and distributed in the cytoplasm, failing to activate Wnt/β-catenin signaling pathway, whereas the wild-type SATB2 translocated into the nucleus and upregulated the expression of activeβ-catenin. When we used Wnt inhibitor XAV939 to treat hDPSCs transfected with wild-type SATB2 plasmid, the increased odontogenic differentiation capacity was attenuated. Furthermore, we found that SATB2 mutation resulted in the upregulation of DKK1 and histone demethylase JHDM1D to inhibit Wnt/β-catenin signaling pathway.Conclusion: We identified a novel frameshift mutation of SATB2 (c.376_378delinsTT, p.Leu126SerfsX6) in a Chinese patient withSATB2-associated syndrome (SAS) exhibiting tooth agenesis. Mechanistically, SATB2 regulated osteo/odontogenesis of human dental pulp stem cells through Wnt/β-catenin signaling pathway by regulating DKK1 and histone demethylase JHDM1D.

Dental pulp stem cells (DPSCs), characterized by easy availability, multi‐lineage differentiation ability, and high proliferation ability, are ideal seed cells for cartilage tissue engineering. However, the epigenetic mechanism underlying chondrogenesis in DPSCs remains elusive. Herein, it is demonstrated that KDM3A and G9A, an antagonistic pair of histone‐modifying enzymes, bidirectionally regulate the chondrogenic differentiation of DPSCs by controlling SOX9 (sex‐determining region Y‐type high‐mobility group box protein 9) degradation through lysine methylation. Transcriptomics analysis reveals that KDM3A is significantly upregulated during the chondrogenic differentiation of DPSCs. In vitro and in vivo functional analyses further indicate that KDM3A promotes chondrogenesis in DPSCs by boosting the SOX9 protein level, while G9A hinders the chondrogenic differentiation of DPSCs by reducing the SOX9 protein level. Furthermore, mechanistic studies indicate that KDM3A attenuates the ubiquitination of SOX9 by demethylating lysine (K) 68 residue, which in turn enhances SOX9 stability. Reciprocally, G9A facilitates SOX9 degradation by methylating K68 residue to increase the ubiquitination of SOX9. Meanwhile, BIX‐01294 as a highly specific G9A inhibitor significantly induces the chondrogenic differentiation of DPSCs. These findings provide a theoretical basis to ameliorate the clinical use of DPSCs in cartilage tissue‐engineering therapies.

Bone homeostasis and skeletal fragility are sexually dimorphic in humans, with postmenopausal women at the highest risk of osteoporosis. Here, we identify X-linked methyltransferase SUV39H1 as a suppressor of osteogenesis in females. Both experiments in primary samples and Suv39h1-deficient mice show enhanced osteogenesis upon SUV39H1 ablation with gender differences. Transcriptomic analysis reveals the aberrant NF-κB activation and inflammation signatures independent of H3K9me3 underlying SUV39H1-inhibited osteogenesis. Surprisingly, SUV39H1 shows a unique cytoplasmic distribution in female osteoblasts and is directly engaged in inflammation response by catalyzing IκBα methylation at lysine 38 adjacent to its degradation motif. This SUV39H1-deposited methylation mark signals UACA binding and subsequently restrains bone formation by provoking IκBα destabilization. Importantly, intrinsically improved osteogenesis by Suv39h1 depletion ameliorates ovariectomy-induced osteoporotic bone loss. Together with the chronologically elevated female SUV39H1 levels, these data identify an SUV39H1-governed molecular amplifier in sexually divergent skeletal remodeling and highlight its potential as therapeutic avenue for osteoporosis.

Aging severely impairs the beneficial effects of human dental pulp stem cells (hDPSCs) on cartilage regeneration. Lysine demethylase 3A (KDM3A) is involved in regulating mesenchymal stem cells (MSCs) senescence and bone aging. In this study, we investigated the role of KDM3A in hDPSCs aging and whether KDM3A could rejuvenate aged hDPSCs to enhance their chondrogenic differentiation capacity. The cellular aging of hDPSCs was evaluated by senescence-associated β-galactosidase (SA-β-gal) staining. Protein levels were determined using Western blot analysis. KDM3A was overexpressed in aged hDPSCs by lentivirus infection. Quantitative reverse-transcription polymerase chain reaction (RT-qPCR) were used to determine the mRNA levels of stemness markers. Toluidine blue staining was used to evaluate the effect of KDM3A overexpression on the chondrogenic differentiation of aged hDPSCs. hDPSCs at passage 12 or treated with etoposide exhibited augmented cellular senescence as evidenced by increased SA-β-gal activity. KDM3A was significantly increased during senescence of hDPSCs. Overexpression of KDM3A did not affect the stemness properties but significantly promoted the chondrogenic differentiation of aged hDPSCs. Our findings indicate that KDM3A plays an important role in the maintenance of the chondrogenic differentiation capacity of aged hDPSCs and suggest that therapies targeting KDM3A may be a novel strategy to rejuvenate aged hDPSCs.