Project description:Mandibular prognathism (MP) is the most common type of dento-maxillofacial deformity in East Asian populations. Genetic studies have revealed several MP-associated loci, suggesting that MP could be inherited as familial MP (fMP). However, functional verifications and in-depth mechanistic investigations of these loci are limited. For this study, we recruited 5 fMP families with 17 fMP members and 7 normal members. We first compared the clinical features of the 17 fMP members with 31 non-familial MP patients, finding a stronger mandibular overgrowth phenotype in the fMP subjects. Next, we performed whole-exome sequencing (WES) analysis with members of the 5 fMP families and singled out a potential fMP-associated pathogenic variant in the CASR gene—namely, rs117375173—the mutation introduces an amino acid substitution (A601G) in exon 7 and confers gain-of-function in Calcium-Sensing Receptor (CaSR). The rs11735173 variant changes the CaSR protein structure toward a semi-active state, similar to CaSR activated by L-tryptophan (L-Trp). To verify the regulating roles of CASR in mandibular bone growth, we further generated different mouse models with abnormal CaSR function. L-Trp administration effectively activate CaSR/GNAQ expression in vivo and in vitro. The MC3T3-E1 cell line transfected with CaSR with rs117375173 showed increased osteogenic differentiation and collagen synthesis at transcriptional level. Local injection of L-Trp in the mandible of growing mice significantly increased the mandibular length and BMD, due to activated osteogenic activity and suppressed bone resorption. At the same time, loss-of-function of CaSR in osteogenic progenitors caused mandibular growth retardation in Gli1-CreER; Casrfl/fl; tdTomatofl/+ mice. In conclusion, our study reveals that abnormal functioning of CaSR affects mandibular bone development and may contribute to the pathogenesis of fMP, providing a theoretical and experimental basis for the early diagnosis of and therapeutic strategies for fMP in clinical practice.
Project description:Cell size and the cell cycle are intrinsically coupled and abnormal increases in cell size are associated with senescence and permanent cell cycle arrest. The mechanism by which overgrowth primes cells to withdraw from the cell cycle remains unknown. We investigate this here using CDK4/6 inhibitors that arrest cell cycle progression during G0/G1 and are used in the clinic to treat ER+/HER2- metastatic breast cancer. We demonstrate that CDK4/6 inhibition promotes cellular overgrowth during G0/G1, causing p38MAPK-p53-p21-dependent cell cycle withdrawal. We find that cell cycle withdrawal is triggered by two waves of p21 induction. First, overgrowth during a long-term G0/G1 arrest induces an osmotic stress response. This stress response produces the first wave of p21 induction. Second, when CDK4/6 inhibitors are removed, a fraction of cells escape long term G0/G1 arrest and enter S-phase where overgrowth-driven replication stress results in a second wave of p21 induction that causes cell cycle withdrawal from G2, or the subsequent G1. We propose a model whereby both waves of p21 induction contribute to promote permanent cell cycle arrest. This model could explain why cellular hypertrophy is associated with senescence and why CDK4/6 inhibitors have long-lasting effects in patients.
Project description:Single-cell gene expression of mandibular bone marrow cells and mandibular bone marrow cells under the stimulation of apical periodontitis were determined by scRNAseq.
Project description:Single-cell gene expression of mandibular bone marrow cells and mandibular bone marrow cells under the stimulation of BRONJ were determined by scRNAseq.
Project description:Fusion of branchial arch derivatives is an essential event in the development of craniofacial architecture. A unique feature of the mandibular arch development is medial/lateral compartmentalization for the molecular networks. Those networks give rise to multiple region-specific organs, namely teeth, a tongue, salivary glands, and the supporting matrices such as bones and cartilages. We aimed to investigate molecular networks that govern the fusion process during mouse mandibular development. To this end, cDNA microarray technology was employed for screening of spatio-temporal gene expression in developing mandibular arch from E9.7 through E11.5. We conducted to divide a mandibular arch medially and laterally to compare both gene expression. From an embryo at E10.5, a medial (M) sample of the mandibular arch was dissected out -at just the distal end of opposed lateral lingual swellings-, and the bulk of remnant lateral region was collected as (L) sample under a stereomicroscope. Forty embryos for each time-point were used to obtain a pool of total RNA.
Project description:Fusion of branchial arch derivatives is an essential event in the development of craniofacial architecture. A unique feature of the mandibular arch development is medial/lateral compartmentalization for the molecular networks. Those networks give rise to multiple region-specific organs, namely teeth, a tongue, salivary glands, and the supporting matrices such as bones and cartilages. We aimed to investigate molecular networks that govern the fusion process during mouse mandibular development. To this end, cDNA microarray technology was employed for screening of spatio-temporal gene expression in developing mandibular arch from E9.7 through E14.5.
Project description:Gene expression of mandibular precursor from embryonic day 13.5 trisomic and euploid embryos from the Ts65Dn Down syndrome mouse model. Results provide insight into importance of non-trisomic genes in organogenesis. Total RNA isolated from mandibular precursor of 13 trisomic and 11 euploid E13.5 embryos.