The significance of aryl acylamidase activity of acetylcholinesterase in osteoblast differentiation and mineralization.

Osteoblast differentiation is an essential event in the developmental process, which is favoured by the production of extra cellular matrix proteins and various enzymes including discrete ones like acetylcholinesterase (AChE). Despite the fact that AChE facilitates osteoblast differentiation, the significance of its catalytic functions [esterase and aryl acylamidase (AAA) activities] in the process is yet to be ascertained. In this context, SaOS-2 cell line was used in the present study to implicate the catalytic activities of AChE in process of osteoblast differentiation and mineralization. During differentiation, it was found that the activity of both esterase and AAA increased 1.13 and 1.46 folds respectively, signifying the involvement of catalytic activities of AChE in the process. Inhibition of both the catalytic activities of AChE with edrophonium significantly reduced the amount of mineralization by decreasing the alkaline phosphatase (ALP) activity and expression of differentiation-related genes such as RUNX-2, COL1A, ALP, OC, and OP significantly (p < 0.05). Inhibition of esterase activity without altering the AAA activity using gallamine significantly increased the level ALP activity and expression of differentiation-associated genes (p < 0.05), thus favouring mineralization. Therefore, this study concludes and confirms that the AAA activity of AChE is actively involved in the process of osteoblast differentiation and mineralization.