Substrate Stiffness Regulates the Proliferation and Apoptosis of Periodontal Ligament Cells through Integrin-Linked Kinase ILK.

The hallmark of orthodontic tooth movement (OTM) is time-consuming during clinical treatments. The acceleration of OTM through modulating proliferation and apoptosis of periodontal ligament cells (PDLCs) possesses the potential application in clinical treatments. Here, we established an in vitro model with a graded increase in substrate stiffness to investigate the underlying mechanism of proliferation and apoptosis of PDLCs. The role of the integrin-linked kinase (ILK) in response to substrate stiffness was investigated by the depletion model of PDLCs. We found that the proliferation and apoptosis of PDLCs show a stiffness-dependent property with stiffer substrates favoring increased bias at the transcript level. Depleting integrin-linked kinase diluted the correlation between PDLCs behaviors and substrate stiffness. Our results suggest that ILK plays a significant role in modulating PDLC proliferation and apoptosis and can serve as a potential target for accelerating OTM.

Hyoid bone position in subjects with different facial growth patterns of different dental ages.

OBJECTIVE: To explore the correlation between hyoid bone (HB) positions and facial growth patterns (facial patterns) in Chinese adults; to identify any significant difference in HB position among subjects with different facial patterns in various dental ages. METHODS: Lateral cephalometric radiographs of 197 Chinese subjects were divided into nine groups based on their dental ages and facial patterns. Seven measurements were used to define HB position. Regression, correlation analyses, and one-way ANOVA were carried out. RESULTS: Significant correlations were found between facial patterns and anteroposterior HB positions. The HB was more anterior in the horizontal group after mixed dentition and further away from the mandibular plane in the vertical group of adults. Vertical HB positions were insignificantly different in any stage. CONCLUSION: HB position and facial patterns were correlated. There were significantly different HB positions among people with different facial patterns in various dental ages.

Role of integrin­linked kinase in static compressive stress­induced autophagy via phosphatidylinositol 3 kinase in human periodontal ligament cells.

Orthodontic tooth movement (OTM) is achieved by using mechanical stimuli, which lead to the remodeling of periodontal tissues. Previous findings have demonstrated that autophagy may be one of the cell responses to mechanical stress. As a key structure in the integrin pathway, integrin linked­kinase (ILK) may play a role in the transmission of these mechanical signals. In addition, ILK is an important upstream molecule that regulates autophagy, under the influence of phosphatidylinositol 3 kinase (PI3K). Therefore, exploring the effect of mechanical stress on autophagy and the associated role of ILK/PI3K is of utmost significance to understanding the mechanism behind OTM. In the present study, human periodontal ligament cells (hPDLCs) were embedded into a collagen­alginate complex hydrogel for three­dimensional (3D) culturing. Static compressive stress (2.5 g/cm2) was loaded using the uniform weight method for 5, 15, 30, and 60 min. The autophagy of hPDLCs was detected by the expression of Beclin­1 (BECN1) and ATG­5 using RT­qPCR and LC3, respectively, using immunofluorescence. The results showed that the level of autophagy and gene expression of ILK increased significantly under static compressive stress. In ILK­silenced cells, static compressive stress could also upregulate ILK expression and increase the levels of autophagy. After PI3K inhibition, the increase in the autophagy level and the upregulation of ILK expression disappeared. These findings suggest that static compressive stress can induce autophagy in hPDLCs in a rapid, transient process, regulated by ILK and PI3K. Moreover, this static stress can upregulate ILK expression in a PI3K­dependent manner.

[Preliminary study on response and its mechanism of ginsenoside biosynthesis in Panax ginseng to water regulation].

The study is aimed to explore the effect of soil moisture content on ginsenoside biosynthesis and explain its mechanism from the perspectives of antioxidant enzyme system and gene expression of key enzymes in the pathway of ginsenoside synthesis. In the study,two years old Panax ginseng was used as the experimental material and three moisture gradient,40% of saturated water content( W1),60%( W2),80%( W3) were set up. The content of 11 monomeric saponins were determined by HPLC. With GAPDH as a reference gene,six key enzymes( HMGR,SS,ß-AS,CYP716 A47,CYP716 A52 v2,CYP716 A53 v2) in ginseng saponin synthesis pathway expression were analyzed by fluorescent quantitative PCR and the activities of superoxide dismutase( SOD),peroxidase( POD),catalase( CAT) activity and MDA content were also determined. With the increase of soil water,the content of ginseng saponin and biomass showed an increasing trend. PPD( Rb1,Rc,Rb2,Rd,Rh2,Rb3,Rg3),PPT( Rg1,Re,Rf) ginsenoside,Ro and total ginsenoside reached the maximum value on August 30,were 9.92,5.48,0.63 mg·g-1,respectively. During the whole regulation period,the antioxidant activity of W3 was greater than that of W1,and the MDA content was less than that of W1. At W3,expression levels of ß-AS,CYP716 A47 and CYP716 A53 v2 showed an increasing trend,while HMGR and SS genes showed relatively stable expression levels under various water conditions. According to the correlation analysis,HMGR and SS genes in the W3 treatment group were significantly positively correlated with PPD,PPT ginsenoside and Ro,CYP716 A52 v2 gene was significantly positively correlated with Ro,and CYP716 A47 gene was significantly positively correlated with PPD ginsenoside. There was a significant positive correlation between ß-AS gene and PPD ginsenoside in W1 and W2 treatment. Therefore,W3 is the optimum moisture content,ginseng total saponins and monomer saponin content is the highest,the gene closely correlation with content of saponins and more conducive to the accumulation of ginsenosides.