Brain-derived Neurotrophic Factor Stimulates Bone/Cementum-related Protein Gene Expression in Cementoblasts

Abstract

Brain-derived neurotrophic factor (BDNF), recognized as essential in the developing nervous system, is involved in differentiation and proliferation in non-neuronal cells, such as endothelial cells, osteoblasts, and periodontal ligament cells. We have focused on the application of BDNF to the regeneration of periodontal tissue and indicated that BDNF promotes the regeneration of experimentally created periodontal defects. Cementoblasts form cementum, mineralized tissue, which is key to establishing a functional periodontium. The application of BDNF to the regeneration of periodontal tissue requires elucidation of the mechanism by which BDNF regulates the functions of cementoblasts. In this study, we examined how BDNF regulates the mRNA expression of bone/cementum-related proteins (alkaline phosphatase (ALP), osteopontin (OPN), and bone morphogenetic protein-2 (BMP-2)) in cultures of immortalized human cementoblast-like (HCEM) cells. BDNF elevated the mRNA levels of ALP, OPN, and BMP-2 in HCEM cells. Small interfering RNA (siRNA) for TRKB, a high affinity receptor of BDNF, siRNA for ELK-1, which is a downstream target of ERK1/2, and PD98059, an ERK inhibitor, obviated the increase in the mRNA levels. BDNF increased the levels of phosphorylated ERK1/2 and Elk-1, and the blocking of BDNF signaling by treatment with siRNA for TRKB and PD98059 suppressed the phosphorylation of ERK1/2 and Elk-1. Furthermore, BDNF increased the levels of phosphorylated c-Raf, which activates the ERK signaling pathway. These findings provide the first evidence that the TrkB-c-Raf-ERK1/2-Elk-1 signaling pathway is required for the BDNF-induced mRNA expression of ALP, OPN, and BMP-2 in HCEM cells.

Brain‐derived neurotrophic factor induces migration of endothelial cells through a TrkB–ERK–integrin αVβ3–FAK cascade

“…2B). A typical three-band pattern, with of 80, 110, and 140 kDa forms were detected as reported (Kajiya et al, 2008). In addition, Western blotting indicated that BDNF stimulated the phosphorylation of ERK, with a maximal effect seen at 30 min A: Wound healing assay.…”

The Antimicrobial Peptide LL37 Induces the Migration of Human Pulp Cells: A Possible Adjunct for Regenerative Endodontics

“…The HP cells were washed three times with PBS, and then samples of the cells were prepared as previously described (29). The samples were then resolved on a 12% sodium dodecyl sulfate-polyacrylamide gel by electrophoresis under nonreducing conditions and electrophoretically transferred onto PVDF membranes (Bio-Rad Laboratories, Hercules, CA).…”

Brain‐derived neurotrophic factor protects cementoblasts from serum starvation‐induced cell death

“…In our previous study, although BDNF activated both the ERK1/2 and NF-kB signaling pathways in HCEM cells, only the ERK1/2 signaling pathway was found to be involved in the elevation of the bone/cementum-related gene expression induced by BDNF (Kajiya et al, 2008). In contrast, the activation of ERK1/2 signaling by BDNF is not involved in cell survival, even though NF-kB signaling is involved in the rescue of HCEM cells from death due to serum starvation.…”

“…In neuronal cells, the two signaling pathways triggered by BDNF contribute to cell survival under certain conditions, depending on the cell type and survival factors. Our previous studies have shown that BDNF enhances the gene expression of bone/cementum-related proteins through the TrkB-c-Raf-ERK1/2-Elk-1 signaling pathway in human cementoblast-like (HCEM) cells (Kajiya et al, 2008). Therefore, we hypothesized that BDNF activates the PI3-kinase-Akt signaling pathway as well as the ERK1/2 pathway to regulate cell survival in HCEM cells.…”