Influence of Adiponectin on the Rodent Cementoblasts Hemeostasis and Signaling Pathway Interaction under Compressive Force

Abstract

In obese patients, current clinical evidences suggest that changes in levels of circulating adipokines such as adiponectin can influence the speed of orthodontically induced tooth movement due to their capacity to regulate peripheral bone formation. Here, qRT-PCR and Western blots were performed to verify the mRNA and protein levels of adiponectin receptors (AdipoRs) of OCCM-30 cells. Alizarin Red S staining revealed that adiponectin increased mineralized nodule formation and quantitative AP activity in a dose-dependent manner. Adiponectin up-regulates the mRNA levels of AP, BSP, OCN, OPG, Runx-2 as well as F-Spondin. Adiponectin also increases the migration and proliferation of OCCM-30 cells. Moreover, Adiponectin induces a transient activation of JNK, P38 and ERK1/2. The activation of adiponectin-mediated migration and proliferation was attenuated after pharmacological inhibition of P38, ERK1/2 and JNK in different degrees, whereas mineralization was facilitated by MAPK inhibition in varying degrees. Based on our results, I showed that adiponectin could favorably affect cementoblast migration, proliferation as well as cementogenesis partly through the activation of MAPK signaling pathways. Furthermore, siRNAs targeting P38α, JNK1, ERK1, ERK2 and AdipoRs were performed. It was found that compressive forces increased the expression of AdipoRs. Western blots showed that co-stimuli of adiponectin and compression activated MAPK and β-Catenin signaling pathways. The MAPK inhibition alters the compression-induced β-Catenin activation. The siRNAs targeting AdipoR1, P38α and JNK1 showed the interaction of single MAPK molecules and β-Catenin signaling in response to compression and/or adiponectin. Silencing by a dominant negative-version of P38α and JNK1 attenuated adiponectin-induced TCF/LEF reporter activation. P38α is a key connector between β-Catenin, TCF/LEF transcription and MAPK signaling pathway. In conclusion, compressive forces activate β-Catenin and MAPK signaling pathways. Adiponectin regulates β-Catenin signaling principally by inactivating GSK-3β kinase activity. β-Catenin expression was partially inhibited by MAPK blockade indicating that MAPK plays a crucial role regulating β-Catenin during cementogenesis. Moreover, adiponectin modulates GSK-3β and β-Catenin mostly through AdipoR1.