Which transcription factor is essential for hindlimb specification?
Hindlimb specification integrates Islet1, Pitx1 and Tbx4 transcriptional network in caudal lateral plate mesoderm governing positional identity. Pitx1, a bicoid-type homeodomain factor, is expressed specifically in hindlimb mesenchyme, activating Tbx4 and other hindlimb genes such as Hoxc10, while repressing forelimb program, dictating hindlimb morphology including patella, flexed knee and differential muscle pattern. Pitx1 knockout partially transforms hindlimbs toward forelimb identity and causes clubfoot-like phenotypes with altered musculature. TBX5 drives forelimb, SOX9 chondrogenesis, PA
Ref: Gilbert, Developmental Biology, 12th ed., Chapter 20: PITX1 and TBX4 in hindlimb specification.
