Cell cycle-regulated ApiAP2s and parasite development: the Toxoplasma paradigm.

The cell division cycle of T. gondii is driven by cyclically expressed ApiAP2 transcription factors (AP2s) that promote gene sets (regulons) associated with specific biological functions. AP2s drive other AP2s, thereby propelling the progressive gene expression waves defining the lytic cycle. AP2s can act as dimers by themselves, in combination with other AP2s (constitutive or cyclical) or in complexes with epigenetic factors. Exit from the cell cycle into either the extracellular state or differentiation into bradyzoites results in major changes in gene expression. Surprisingly, both transitions lead to expression of a shared set of unique AP2s that suggest a shared stress response that, governed by the specific conditions, leads to different outcomes. • AP2 factors are the major gene expression drivers of the T. gondii cell cycle. • AP2 factors can act as activators or repressors in complex with other players. • A distinct, shared set of AP2 is associated with various exogenous stresses. • New tools now permit comprehensive dissection of the AP2-driven programs. [ABSTRACT FROM AUTHOR]