Practice question

L-Maf, a large Maf bZIP transcription factor expressed in lens placode downstream of Pax6, Sox2, and FGF-BMP signaling, directly regulates crystallin genes essential for transparency. L-Maf binds Maf recognition elements in delta-crystallin enhancer in chick and alphaA-crystallin promoter in mammals, activating high-level expression during fiber cell elongation and organelle loss. It does not induce optic vesicle formation, inhibit Sox2, or prevent corneal differentiation. L-Maf knockout lenses show severe deficiency in crystallin accumulation and fiber elongation arrest, confirming its central role in regulating structural lens genes and differentiation.