Abstract
MicroRNAs (MiRNAs) are small endogenous non-coding RNAs that bind to the 3′-untranslated region of target genes and promote their degradation or inhibit translation, thereby regulating gene expression. MiRNAs are ubiquitous in biology and are involved in many biological processes, playing an important role in a variety of physiological and pathological processes. MiRNA-21 (miR-21) is one of them. In recent years, miR-21 has received a lot of attention from researchers as an emerging player in orthopedic diseases. MiR-21 is closely associated with the occurrence, development, treatment, and prevention of orthopedic diseases through a variety of mechanisms. This review summarizes its effects on osteoblasts, osteoclasts and their relationship with osteoporosis, fracture, osteoarthritis (OA), osteonecrosis, providing a new way of thinking for the diagnosis, treatment and prevention of these bone diseases.
Highlights
MiRNAs, first discovered by Lee et al in elegans, are a class of endogenous non-coding small RNAs that play an important regulatory role in gene expression at the post-transcriptional level (Lee et al, 1993; Zhang et al, 2012)
Promotes mesenchymal stem cells (MSCs) osteogenesis through the miR-21/SPRY1 functional axis inhibits the expression of SPRY2, activates ERK-MAPK signal pathway, and increases the level of transcription factors related to osteogenic differentiation inhibits the expression of SOX2 and accelerates osteogenesis activates the PI3K-AKT-GSK3β pathway and promotes the entry of β-catenin into the nucleus, promoting osteogenic differentiation promotes osteogenic differentiation through SMAD7-SMAD1/5/8-RUNX2 pathway promotes osteogenic differentiation and mineralization by inhibiting the expression of SMAD7 promotes osteogenic differentiation by reducing the level of SMAD7 to maintain the activation of BMP9/ SMAD signal promotes the osteogenic differentiation of periodontal ligament cells (PDLCs) by regulating the expression of PLAP-1 promotes stretch-induced osteogenic differentiation by inhibiting the expression of ACVR2B
They established a cell model of osteoporosis by adding tumor necrosis factor-α (TNF-α) to the medium of MSCs and found that miR-21 mimics as well as RECK siRNA attenuated the effects of TNF-α on apoptosis, proliferation and differentiation of MSCs, and increased the expression of MT1-MMP
Summary
MiRNAs, first discovered by Lee et al in elegans, are a class of endogenous non-coding small RNAs that play an important regulatory role in gene expression at the post-transcriptional level (Lee et al, 1993; Zhang et al, 2012). Mesenchymal stem cells (MSCs) are a kind of multipotent stem cell with the potential of multi-directional differentiation (Lin et al, 2019) It is the precursor cell of osteoblasts and osteocytes in the process of bone formation (Hou et al, 2021). MiR-21 maintains the activation of ERK-MAPK signaling by decreasing the level of SPRY2, thereby increasing the expression of osteogenic differentiation-related transcription factors (Mei et al, 2013). MiR-21 can promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs) by targeting the SMAD7-SMAD1/5/8-RUNX2 pathway (Li et al, 2017)
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