Intermittent parathyroid hormone promotes cementogenesis in a PKA‐ and ERK1/2‐dependent manner

Abstract

Background: Intermittent parathyroid hormone (PTH) promotes cementogenesis and provides a promising biotherapeutic to rehabilitate resorbed roots. However, the underlying mechanisms remain inconclusive. Cyclic aenosine monophosphate (AMP)-dependent protein kinases A (PKA) and extracellular signal-regulated MAP kinases 1/2 (ERK1/2) are key regulators of bone remodeling. The present study aims to investigate whether PKA and ERK1/2 are involved in the process of intermittent PTH-promoted cementogenesis.Methods: Sprague-Dawley rats in experimental group (n = 30) received a daily subcutaneous injection of PTH and the control (n = 30) received placebo vehicle for 1, 2, 3, 4, and 5 weeks. Results were evaluated by hematoxylin and eosin and immunohistochemistry staining. In vitro, OCCM-30 cells were incubated with intermittent PTH. H89 and U0126 were used to determine the role of PKA and ERK1/2, respectively. The cementogenic results were analyzed by reverse transcription-polymerase chain reaction (RT-PCR), western blotting, alkaline phosphatase activity assay and Alizarin Red S staining. The interaction of PKA and p-ERK1/2 was determined by co-immunoprecipitation (Co-IP). Results:Intermittent PTH exerted anabolic effect on cellular cementum in developing teeth with elevated expression of osteocalcin, osteopontin, and PKA (catalytic subunit) in PTH injection group. The promoting effects of intermittent PTH on cementogenesis and osteogenic differentiation were abrogated by H89 and U0126 in vitro, respectively. Blocking of PKA pathway downregulated intermittent PTH-induced ERK1/2 phosphorylation. Conclusions:Intermittent PTH promotes cementogenesis in a PKA-and ERK1/2dependent manner. In this process, PKA and p-ERK1/2 interact with each other. These results support the future biotherapeutic applications of PTH in cementum resorption.

Intermittent parathyroid hormone promotes cementogenesis via ephrinB2‐EPHB4 forward signaling

“…PTH exerts anabolic effects on cementum formation of developing teeth in young rats and these effects were also confirmed by in vitro studies (Y. Li et al, 2017;Silva, Vasconcelos, Marques, & Barros, 2016;Xu et al, 2019). Taken together, these findings strongly support that intermittent PTH administration does have the capacity for promoting the anabolic activity of cementoblasts and facilitating the healing process of OIRR.…”

“…Western blots were performed as described previously (Hu et al, 2018;Xu et al, 2019). The primary antibodies used in this study were EPHB4…”

Intermittent parathyroid hormone improves orthodontic retention via insulin‐like growth factor‐1

“…Results showed that high dose of iPTH may counteract part of the inhibition effects of BMS‐536924. As shown by previous studies, iPTH may exert its biological effects through else signaling pathways other than IGF‐1 (Xu et al., 2019). Even so, the mineralization activities of high PTH + inhibitor groups were still significantly weaker than the PTH group.…”

“…Then, the animals were randomly divided into 2 groups of 24 animals each: the PTH group and the control group. From the first day of maintenance phase, the animals in the experimental group received a daily injection of PTH (1–34) (Bachem) at a dosage of 4 mg per 100 g of body weight, while the control group received the same volume of vehicle (0.1% acetic acid; Li et al., 2013; Xu et al., 2019). After 4 weeks, the orthodontic wires were detached and maxillary first molars endured a relapsing phase for 2 weeks (Figure 1c).…”

“…Western blots were performed as described previously (Xu et al., 2019). The primary antibodies used in this study were ALP (dilution 1:2000, ET1601‐21, huabio), OCN (dilution 1:500, ER1803‐43, huabio), cementum attachment protein (CAP, dilution 1:200, SC‐53947, Santa Cruz), runt‐related transcription factor 2 (Runx2, dilution 1:1,000, ET1612‐47, huabio), and GAPDH (dilution 1:10,000, ab181602, Abcam).…”