Gene expression profiles and bioinformatics analysis of insulin-like growth factor-1 promotion of osteogenic differentiation

Compression Promotes the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Regulating METTL14-mediated IGF1

BACKGROUND AND OBJECTIVES

Orthodontic treatment involves the application of mechanical force to induce periodontal tissue remodeling and ultimately promote tooth movement. It is essential to study the response mechanisms of human periodontal ligament stem cells (hPDLSCs) to improve orthodontic treatment.

METHODS

In this study, hPDLSCs treated with compressive force were used to simulate orthodontic treatment. Cell viability and cell death were assessed using the CCK-8 assay and TUNEL staining. Alkaline phosphatase (ALP) and alizarin red staining were performed to evaluate osteogenic differentiation. The binding relationship between IGF1 and METTL14 was assessed using RIP and dual-luciferase reporter assays.

RESULTS

The compressive force treatment promoted the viability and osteogenic differentiation of hPDLSCs. Additionally, m6A and METTL14 levels in hPDLSCs increased after compressive force treatment, whereas METTL14 knockdown decreased cell viability and inhibited the osteogenic differentiation of hPDLSCs treated with compressive force. Furthermore, the upregulation of METTL14 increased m6A levels, mRNA stability, and IGF1 expression. RIP and dual-luciferase reporter assays confirmed the interaction between METTL14 and IGF1. Furthermore, rescue experiments demonstrated that IGF1 overexpression reversed the effects of METTL14 knockdown in hPDLSCs treated with compressive force.

CONCLUSIONS

In conclusion, this study demonstrated that compressive force promotes cell viability and osteogenic differentiation of hPDLSCs by regulating IGF1 levels mediated by METTL14.

Preparation, characterization, and osteogenic activity mechanism of casein phosphopeptide-calcium chelate

Casein phosphopeptides (CPPs) are good at calcium-binding and intestinal calcium absorption, but there are few studies on the osteogenic activity of CPPs. In this study, the preparation of casein phosphopeptide calcium chelate (CPP-Ca) was optimized on the basis of previous studies, and its peptide-calcium chelating activity was characterized. Subsequently, the effects of CPP-Ca on the proliferation, differentiation, and mineralization of MC3T3-E1 cells were studied, and the differentiation mechanism of CPP-Ca on MC3T3-E1 cells was further elucidated by RNA sequencing (RNA-seq). The results showed that the calcium chelation rate of CPPs was 23.37%, and the calcium content of CPP-Ca reached 2.64 × 10⁵ mg/kg. The test results of Ultraviolet–Visible absorption spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR) indicated that carboxyl oxygen and amino nitrogen atoms of CPPs might be chelated with calcium during the chelation. Compared with the control group, the proliferation of MC3T3-E1 cells treated with 250 μg/mL of CPP-Ca increased by 21.65%, 26.43%, and 28.43% at 24, 48, and 72 h, respectively, and the alkaline phosphatase (ALP) activity and mineralized calcium nodules of MC3T3-E1 cells were notably increased by 55% and 72%. RNA-seq results showed that 321 differentially expressed genes (DEGs) were found in MC3T3-E1 cells treated with CPP-Ca, including 121 upregulated and 200 downregulated genes. Gene ontology (GO) revealed that the DEGs mainly played important roles in the regulation of cellular components. The enrichment of the Kyoto Encyclopedia of Genes and Genomes Database (KEGG) pathway indicated that the AMPK, PI3K-Akt, MAPK, and Wnt signaling pathways were involved in the differentiation of MC3T3-E1 cells. The results of a quantitative real-time PCR (qRT-PCR) showed that compared with the blank control group, the mRNA expressions of Apolipoprotein D (APOD), Osteoglycin (OGN), and Insulin-like growth factor (IGF1) were significantly increased by 2.6, 2.0 and 3.0 times, respectively, while the mRNA levels of NOTUM, WIF1, and LRP4 notably decreased to 2.3, 2.1, and 4.2 times, respectively, which were consistent both in GO functional and KEGG enrichment pathway analysis. This study provided a theoretical basis for CPP-Ca as a nutritional additive in the treatment and prevention of osteoporosis.

Bone remodeling: an operational process ensuring survival and bone mechanical competence

Bone remodeling replaces old and damaged bone with new bone through a sequence of cellular events occurring on the same surface without any change in bone shape. It was initially thought that the basic multicellular unit (BMU) responsible for bone remodeling consists of osteoclasts and osteoblasts functioning through a hierarchical sequence of events organized into distinct stages. However, recent discoveries have indicated that all bone cells participate in BMU formation by interacting both simultaneously and at different differentiation stages with their progenitors, other cells, and bone matrix constituents. Therefore, bone remodeling is currently considered a physiological outcome of continuous cellular operational processes optimized to confer a survival advantage. Bone remodeling defines the primary activities that BMUs need to perform to renew successfully bone structural units. Hence, this review summarizes the current understanding of bone remodeling and future research directions with the aim of providing a clinically relevant biological background with which to identify targets for therapeutic strategies in osteoporosis.

Effect of a Bone Morphogenetic Protein-2-derived peptide on the expression of tumor marker ZNF217 in osteoblasts and MCF-7 cells

Zinc Finger Protein 217 (ZNF217), a transcription factor and oncogene product, has been found to dysregulate Bone Morphogenetic Protein (BMP) signaling and induce invasion in breast tumors. In this study, the effect of BMP-2 or an active BMP-2 peptide, AISMLYLDEN, on the expression of ZNF217, BMP4 and CDK-inhibitor p21 gene, CDKN1A, was investigated in MCF-7 breast cancer cells. In parallel, the entire protein (BMP-2) as well as the aforementioned peptide were investigated in hDPSCs during osteogenic differentiation. The treatment of MCF-7 cancer cells with different concentrations of peptide AISMLYLDEN showed that the addition of 22.6 ng/ml was more effective in comparison to the other used concentrations. In particular, 48 h after treatment, CDKN1A and BMP4 mRNA levels were substantially increased in contrast to ZNF217 mRNA levels which were decreased. These results are strongly supported by BrdU assay that clearly indicated inhibition of cancer cell proliferation. Taken together, these results open ways for a concurrent use, at appropriate concentrations, of the peptide AISMLYLDEN during conventional therapeutic treatment in breast tumors with a metastatic tendency to the bones. Regarding the effect of the entire protein as well as its peptide on hDPSCs differentiation into osteocytes, the mRNA levels of osteocalcin, an osteogenic marker, showed that the peptide enhanced osteogenesis at a higher degree in comparison to the entire BMP-2 without however altering ZNF217, CDKN1A and BMP4 expression levels, which remained as expected of non-cancer cells.

Transcriptome Analysis of Egg Yolk Sialoglycoprotein on Osteogenic Activity in MC3T3-E1 Cells

In this study, the effects of egg yolk sialoglycoprotein (EYG) on osteogenesis in MC3T3-E1 cells were investigated and the DEGs (differentially expressed genes) were explored by transcriptome analysis. The results found that EYG effectively increased cell proliferation, enhanced ALP activity, promoted the secretion of extracellular matrix protein COL-I and OCN, enhanced bone mineralization activity, exhibiting good osteogenic activity. Further study of the mechanism was explored through transcriptome analysis. Transcriptome analysis showed that 123 DEGs were triggered by EYG, of which 78 genes were downregulated and 45 genes were upregulated. GO (gene ontology) analysis showed that EYG mainly caused differences in gene expression of biological processes and cell composition categories in the top 30 most enriched items. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis showed that EYG inhibited inflammatory factors and downregulated inflammation-related pathways. The results also showed EYG regulated such genes as COL2A1, COL4A1 and COL4A2 to up-regulate pathways including ECM–receptor interaction, focal adhesion and protein digestion and absorption, enhancing the proliferation and differentiation of osteoblasts. Gene expression of COL-I, Runx2, BMP2 and β-catenin was determined by qRT-PCR for verification, which found that EYG significantly increased COL-I, Runx2, BMP2 and β-catenin gene expression, suggesting that BMP-2 mediated osteogenesis pathway was activated.

Curcumin promotes osteogenic differentiation of human periodontal ligament stem cells by inducting EGR1 expression

OBJECTIVE

Human periodontal ligament stem cells (hPDLSCs) attract attention for the periodontal regeneration therapy. Curcumin may promote osteogenic differentiation of hPDLSCs. This research aims to elucidate whether Curcumin displays promoting osteogenic differentiation and its mechanism.

METHODS

The hPDLSCs were isolated from human periodontal ligament by immunomagnetic beads, identified with immumofluorescence. hPDLSCs were treated with 0, 5, 10, 20, 50, 100 μmol/L Curcumin. The early growth response gene 1 (EGR1) siRNA or plasmind were tranfected into the hPDLSCs. The viability, Alkaline Phosphatase (ALP) activity and mineralizaiton level of hPDLSCs were measured with 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, ALP Assay Kit or Alizarin Red staining. The expression of EGR1, RUNX family transcription factor 2 (Runx2), bone gamma-carboxyglutamate protein (OC), secreted phosphoprotein 1 (OPN) and collagen type I alpha 1 chain (Collagen I), in hPDLSC were determined by Western blotting and quantitative reverse transcription-polymerase chain reaction.

RESULTS

The isolated hPDLSCs were spindle or irregular, arranged in radial shape and shown positive expression of STRO-1, CD146 and Vimentin. Curcumin 10 μmol/L treatment maximal promoting the cells viability, ALP activities, mineralization, and levels of Runx2, OC, OPN, Collagen I and EGR-1 in hPDLSCs. EGR-1 siRNA transfection inversed Curcumin's promoting effect on ALP activities, mineralization, and levels of Runx2, OC, OPN, Collagen I and EGR-1 in hPDLSCs. While the EGR-1 plasmid transfection enhanced Curcumin's promoting effect on these parameters of hPDLSCs.

CONCLUSION

Curcumin promotes the osteogenic differentiation of hPDLSCs, which may work through the EGR1. Curcumin may be a promising medicine for periodontitis treatment and periodontal regeneration.

Gene expression profiles and bioinformatics analysis of insulin-like growth factor-1 promotion of osteogenic differentiation

Background

Insulin‐like growth factor‐1 (IGF‐1) promotes osteoblast differentiation and mineralization. The objective of this study was to investigate the effects of IGF‐1 on proliferation, mineralization, alkaline phosphatase (ALP) synthesis, and gene expression of osteoblast differentiation in MC3T3‐E1 osteoblasts cells, and to explore gene expression profiling differential genes.

Methods

MC3T3‐E1 osteoblasts cells were cultured in medium with or without IGF‐1. The ALP assay was employed to determine the osteoblast mineralization, and Alizarin red S to stain for calcium deposits, which were the indicators of mature osteocytes. The living cell number was assessed by the Cell Counting Kit‐8 method. RNA‐seq analysis was applied to identify genes that were differentially expressed in with or without IGF‐1 as well as genes that varied between these two groups. The expression of osteogenic marker genes was determined by quantitative real‐time polymerase chain reaction (qRT‐PCR) and western blot analysis.

Result

The cell number of osteoblasts exposed to IGF‐1 at 200 μg/L significantly increased compared with the control group. The ALP activity in IGF‐1‐treated cells was higher than that in the control group. IGF‐1 can increase ALP synthesis in osteoblasts in vitro. RNA‐seq analysis showed that 677 triggered differentially expressed genes by IGF, of which 383 genes were downregulated and 294 genes were upregulated. Gene ontology (GO) analysis showed that IGF‐1 caused a significant change in gene expression patterns.

Conclusions

This result suggested that IGF‐1 could probably promote the synthesis of organic matrix and mineralize action of bone. Osteogenic‐related genes (DMP1, PHEX, SOST, BMP2, RUNX2, OPN, and OCN) were significantly upregulated both in GO analysis and in pathway analysis to perform qRT‐PCR. Western blot analysis demonstrated that the Notch pathway was highly upregulated in MC3T3‐E1 cells.