SFRP2 enhances the osteogenic differentiation of apical papilla stem cells by antagonizing the canonical WNT pathway
Jin et al. Cellular & Molecular Biology Letters
SFRP2 enhances the osteogenic differentiation of apical papilla stem cells by antagonizing the canonical WNT pathway
Luyuan Jin 0 2
Yu Cao 0 2
Guoxia Yu 0 2 6
Jinsong Wang 0 5
Xiao Lin 1 2
Lihua Ge 2
Juan Du 2
Liping Wang 2
Shu Diao 2
Xiaomeng Lian 4
Songlin Wang 0 5
Rui Dong 2
Zhaochen Shan 3
0 Molecular Laboratory for Gene Therapy and Tooth Regeneration, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology , No. 4 Tiantanxili, Dongcheng District, Beijing 100050 , China
1 Department of Implant Dentistry, Capital Medical University School of Stomatology , Beijing 100050 , China
2 Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology , No. 4 Tiantanxili, Dongcheng District, Beijing 100050 , China
3 Oral and Maxillofacial Surgery Department, Capital Medical University School of Stomatology , No. 4 Tiantanxili, Dongcheng District, Beijing 100050 , China
4 Department of Stomatology, Beijing Shijitan Hospital, Capital Medical University , Beijing 100045 , China
5 Department of Biochemistry and Molecular Biology, Capital Medical University School of Basic Medical Sciences , No. 10 Xitoutiao Youanmen, Fengtai District, Beijing 100069 , China
6 Department of Stomatology, Beijing Children's Hospital, Capital Medical University , No.56 Nanlishi Road, Xicheng District, Beijing 100045 , China
Background: Exploring the molecular mechanisms underlying directed differentiation is helpful in the development of clinical applications of mesenchymal stem cells (MSCs). Our previous study on dental tissue-derived MSCs demonstrated that secreted frizzled-related protein 2 (SFRP2), a Wnt inhibitor, could enhance osteogenic differentiation in stem cells from the apical papilla (SCAPs). However, how SFRP2 promotes osteogenic differentiation of dental tissue-derived MSCs remains unclear. In this study, we used SCAPs to investigate the underlying mechanisms. Methods: SCAPs were isolated from the apical papilla of immature third molars. Western blot and real-time RT-PCR were applied to detect the expression of βcatenin and Wnt target genes. Alizarin Red staining, quantitative calcium analysis, transwell cultures and in vivo transplantation experiments were used to study the osteogenic differentiation potential of SCAPs. Results: SFRP2 inhibited canonical Wnt signaling by enhancing phosphorylation and decreasing the expression of nuclear β-catenin in vitro and in vivo. In addition, the target genes of the Wnt signaling pathway, AXIN2 (axin-related protein 2) and MMP7 (matrix metalloproteinase-7), were downregulated by SFRP2. WNT1 inhibited the osteogenic differentiation potential of SCAPs. SFRP2 could rescue this WNT1-impaired osteogenic differentiation potential. Conclusions: The results suggest that SFRP2 could bind to locally present Wnt ligands and alter the balance of intracellular Wnt signaling to antagonize the canonical Wnt pathway in SCAPs. This elucidates the molecular mechanism underlying the SFRP2-mediated directed differentiation of SCAPs and indicates potential target genes for improving dental tissue regeneration.
SFRP2; Osteogenic differentiation; Stem cells from apical papilla (SCAPs); Wnt signaling; β-catenin
Background
Mesenchymal stem cells (MSCs) are considered a good cell source for therapies
focused on tissue regeneration [
1
]. First isolated from the bone marrow, MSCs
have since also been successfully obtained from other tissue, like dental tissue,
including periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs),
dental follicle stem cells (DFSCs) and stem cells from apical papilla (SCAPs) [
1–3
].
Displaying the potential to differentiate into various cell types, including
odontoblasts, osteoblasts, chondrocytes, myocytes and adipocytes, these cells are
capable of self-renewal, are easily accessible and more intimately associated with
dental tissues, can generate bone- or dentin-like mineralized tissues, and can repair
tooth defects [
1–5
]. However, their potential clinical applications are limited
because the mechanism underlying their directed differentiation remains largely
unknown.
Wnts are potent regulatory proteins in stem cells, modulating proliferation and
differentiation via both canonical and non-canonical pathways. WNT1, WNT3a
and WNT8 can activate the canonical Wnt signaling pathway, which has β-catenin
as a key mediator [
6
]. Some studies have shown that the Wnt/β-catenin pathway
enhances osteogenesis of MSCs and osteoprogenitor cells by upregulating
osteoblast-related genes [
7
]. However, the pathway has also been reported to inhibit
the osteogenesis capacity of PDLSCs [
8
]. These findings suggest that the canonical
Wnt/β-catenin pathway might play different roles in MSCs derived from different
tissues. Thus, delica (...truncated)