Effect of irisin on the expression of osteoclast-related genes in cementoblasts

Cementoblasts can communicate with osteoclasts by synthesis and secretion of cytokines, such as RANKL, OPG, and M-CSF. Previously, we reported that irisin promotes the differentiation of cementoblasts, while the effect of irisin on cementoblast-mediated osteoclastogenesis remains inconclusive. This study aimed to explore the effect of irisin on the expression of osteoclastogenesis-related cytokines in cementoblasts.

An immortalized murine cementoblast cell line OCCM-30 was used. Immunofluorescence and Western Blot were performed to identify the expression of irisin receptor integrin alphaV and the activation of its downstream signals in OCCM-30 cells. Cells were treated with irisin (100 ng/ml) for various time lengths ranging from 0 to 72 hours, and then qRT-PCR was used to detect the expression of osteoclastogenesis-related genes, including RANKL, IL-6, M-CSF, OPG, Wnt5A, Sema3A. Cells were also incubated with irisin in a series of concentrations (0-200 ng/ml) for 24 hours, and then qRT-PCR and ELISA were performed to examine the above osteoclastogenesis-related cytokines.

Irisin receptor integrin alphaV was expressed in OCCM-30 cells and its downstream signaling pathways were markedly activated by irisin. Both qRT-PCR and ELISA results revealed that RANKL and IL-6 were up-regulated by irisin while M-CSF, OPG, Wnt5A, Sema3A remained unaffected.

OCCM-30 cells were responsive to the stimulation of irisin. The expression of RANKL and IL-6 was significantly enhanced by irisin, suggesting a possible promotive effect on cementoblast-mediated osteoclastogenesis.