Decoding anterior-posterior patterning cues into embryo-wide binary fate decisions through recruitment-mediated targeting.

Developmental pattern formation requires patterning cues to be converted into discrete, gene- and cell-specific regulatory outputs, but how this conversion is achieved remains unclear. We address this problem in Caenorhabditis elegans anterior-posterior patterning, where quantitatively asymmetric Wnt/β-catenin cues, namely anterior-enriched POP-1/TCF and posterior-enriched SYS-1/β-catenin, are decoded into binary, switch-like fate decisions. We show that these cues are resolved into embryo-wide binary regulatory outputs through ZIP-7/DBP, a transcription factor with stage-specific, lineage-wide posterior-exclusive expression that is essential for multiple posterior fate decisions. We define a model for this cue-to-decision decoding. At the zip-7 promoter, the transcription factor ZIP-8/NFIL3, which begins to be expressed during mid-embryogenesis prior to ZIP-7 onset, provides an activating input while recruiting POP-1 and SYS-1. POP-1 restrains this activity anteriorly, whereas the POP-1-SYS-1 complex promotes it posteriorly, thereby generating a binary pattern of zip-7 transcription. This recruitment-mediated promoter control couples Wnt/β-catenin cues to gene-specific transcriptional regulation and enables flexible spatiotemporal control of cue-dependent transcription. Genome-wide analyses further suggest that recruitment-mediated cotargeting may extend beyond zip-7 and point to additional candidate factors with similar recruitment functions, supporting a scalable framework for decoding patterning cues into context-specific regulatory decisions.