Trans-2-Phenylcyclopropylamine induces nerve cells apoptosis in zebrafish mediated by depression of LSD1 activity

Trans-2-phenylcyclopropylamine (referred to as PCPA hereafter; also known as tranylcypromine and Parnate) is used clinically as an antidepressant. Here, we use a new model - zebrafish (Danio rerio) to study the molecular mechanisms of it's adverse reactions in vivo. Following a PCPA exposure (75muM), embryos showed \"sluggish\" action (slow swim and slow escape action). Whole mount in situ hybridization showed that sox1a and huc expressions were downregulated in PCPA-treated embryos, which indicated a decrease in the number of nerve cells. TUNEL assay diplayed that the drop of nerve cells number due to excessive apoptosis. Moreover, lysine specific demethylase1 morpholino injection (LSD1 MO) also induced increases cellular apoptosis in embryos just as PCPA. RT-PCR at 24hpf evaluated that the absence of LSD1 resulted in increased expression of two p53 target genes (p21 and bax2). These findings demonstrate for the first time that PCPA induced apoptosis through inhibition of LSD1 demethylase activity and p53-dependent signaling pathway might be required for the maintenance of nerve cell apoptosis.