Li, L., Zhang, C.W., Chen, G.Y., Zhu, B., Chai, C., Xu, Q.H., Tan, E.K., Zhu, Q., Lim, K.L., Yao, S.Q. (2014). A sensitive two-photon probe to selectively detect monoamine oxidase B activity in Parkinson's disease models.  Nat. Commun. 5(): 3276.

FBrf0250710

Research paper

The unusually high MAO-B activity consistently observed in Parkinson's disease (PD) patients has been proposed as a biomarker; however, this has not been realized due to the lack of probes suitable for MAO-B-specific detection in live cells/tissues. Here we report the first two-photon, small molecule fluorogenic probe (U1) that enables highly sensitive/specific and real-time imaging of endogenous MAO-B activities across biological samples. We also used U1 to confirm the reported inverse relationship between parkin and MAO-B in PD models. With no apparent toxicity, U1 may be used to monitor MAO-B activities in small animals during disease development. In clinical samples, we find elevated MAO-B activities only in B lymphocytes (not in fibroblasts), hinting that MAO-B activity in peripheral blood cells might be an accessible biomarker for rapid detection of PD. Our results provide important starting points for using small molecule imaging techniques to explore MAO-B at the organism level.