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Published on: March 21, 2017
IRF4 suppresses osteogenic differentiation of BM-MSCs by transcriptionally activating miR-636/DOCK9 axis
Xuepu Zhang1, Yue Zhang2, Limin Yang1
1Orthopedics, The First Affiliated Hospital of Jinzhou Medical University, China.
Objectives:
Osteoblasts are derived from Bone Marrow-derived Mesenchymal Stem Cells (BM-MSCs), which play an indispensable role in bone formation. In this study, the authors aim to investigate the role of IRF4 in the osteogenic differentiation of BM-MSCs and its potential molecular mechanism.
Methods:
The authors used lentivirus infection to overexpress IRF4 in BM-MSCs. The expression of IRF4 and osteogenesis-related genes were detected by qRT-PCR and western blot analysis. The osteogenic differentiation of BM-MSCs was evaluated by Alkaline Phosphatase (ALP) activity, Alizarin red staining, and Alkaline Phosphatase (ALP) staining. Chromatin Immunoprecipitation (ChIP), Dual-Luciferase reporter assay and RNA Immunoprecipitation Assay were applied to confirm the regulatory mechanism between IRF4, miR-636 and DOCK9.
Results:
The authors found IRF4 was down-regulated during the osteogenic differentiation of BM-MSCs, and IRF4 overexpression could decrease the osteogenic differentiation of BM-MSCs by specifically promoting the reduction of Alkaline Phosphatase (ALP) activity and down-regulating osteogenic indicators, including OCN, OPN, Runx2 and CollA1. Mechanistically, IRF4 activated microRNA-636 (miR-636) expression via binding to its promoter region, and Dedicator of Cytokinesis 9 (DOCK9) was identified as the target of miR-636 in BM-MSCs. Moreover, the damage in the capacity of osteogenic differentiation of BM-MSCs induced by IRF4 overexpression could be rescued by miR-636 inhibition.
Conclusions:
In summary, this paper proposed that IRF4/miR-636/DOCK9 may be considered as targets for the treatment of osteoporosis (OP).
Insights
Interferon regulatory factor 4 (IRF4) inhibits bone formation by down-regulating osteogenic genes in bone marrow stem cells. Targeting the IRF4/miR-636/DOCK9 pathway may treat osteoporosis.
Area of Science:
- Stem cell biology
- Molecular biology
- Bone biology
Background:
- Osteoblasts, crucial for bone formation, originate from Bone Marrow-derived Mesenchymal Stem Cells (BM-MSCs).
- Understanding the regulatory mechanisms of osteogenic differentiation is vital for bone regeneration and treating bone diseases.
Purpose of the Study:
- To investigate the role of Interferon Regulatory Factor 4 (IRF4) in the osteogenic differentiation of BM-MSCs.
- To elucidate the molecular mechanism underlying IRF4's function in bone formation.
Main Methods:
- Overexpression of IRF4 in BM-MSCs using lentivirus infection.
- Assessment of osteogenic differentiation via Alkaline Phosphatase (ALP) activity, Alizarin red staining, and gene expression analysis (qRT-PCR, Western blot).
- Investigation of the IRF4/miR-636/DOCK9 regulatory axis using Chromatin Immunoprecipitation (ChIP), Dual-Luciferase reporter assay, and RNA Immunoprecipitation Assay.
Main Results:
- IRF4 expression was downregulated during BM-MSC osteogenic differentiation.
- IRF4 overexpression inhibited osteogenic differentiation, reducing ALP activity and key osteogenic markers (OCN, OPN, Runx2, CollA1).
- IRF4 promoted miR-636 expression, which in turn targeted DOCK9, thereby inhibiting osteogenesis. Inhibition of miR-636 rescued the differentiation defect.
Conclusions:
- IRF4 negatively regulates osteogenic differentiation of BM-MSCs.
- The IRF4/miR-636/DOCK9 signaling pathway is identified as a novel mechanism controlling bone formation.
- This pathway presents potential therapeutic targets for osteoporosis treatment.
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