A cell-cycle–dependent GARP-like transcriptional repressor regulates the initiation of differentiation in Giardia lamblia

Abstract

Significance Transition between life cycle stages is a common feature among parasitic pathogens, and its regulation must be optimized to balance persistence of infection with transmission. The early transcription factors (TFs) regulating commitment to differentiate are totally unknown in Giardia . In this work, we identified Golden2, ARR-B, Psr-1–like protein 1 (GARP)–like protein 4 (GLP4), a previously uncharacterized GARP-like TF, as an early-acting transcriptional repressor that inhibits G1+S cells from entering the encystation pathway. GLP4 is therefore a key regulator controlling the balance between proliferative growth and terminal differentiation into infective cysts.