In vitro production of cat-restricted Toxoplasma pre-sexual stages by epigenetic reprogramming [ChIP-seq]

Here we show that AP2XII-1 and AP2XI-2, two transcription factors expressed in tachyzoites, a stage that causes acute toxoplasmosis, silence genes specific to merozoites, a developmental stage critical for sexual commitment and transmission to the next host, including humans. Their conditional and simultaneous depletion leads to a drastic change in the transcriptional program, promoting a complete transition from tachyzoites to merozoites. Pre-gametes produced in vitro are characterized by specific protein markers and undergo typical asexual endopolygenic division cycles. AP2XII-1 and AP2XI-2 bind DNA as heterodimers at merozoite promoters and recruit the epigenitors MORC and HDAC3, which in turn restrict the accessibility of chromatin to the transcriptional machinery. We report genome-wide AP2-XII-1, AP2-XI-2, MORC and HDAC3, profiles in Toxoplasma gondii RHKU80 using ChIP-seq in the context of inducible knock downs of AP2-XII-1, AP2-XI-2 or both simultaneously.