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#interdigital apoptosis

2 public questions tagged with this topic.

Limb Development -ll

Which molecule is essential for interdigital apoptosis?

Digit individualization depends on BMP-driven apoptosis of interdigital tissue executed by conserved cell death pathways and lysosomal activation. BMP4 binds BMPR1B activating phosphorylated Smad1-5 and upregulating Msx2 and proapoptotic Bax caspase-9 cascade in interdigital necrotic zones, while Noggin and Gremlin protect digit rays allowing Sox9 chondrogenesis and collagen II synthesis. Genetic inactivation of BMP4, Bmpr1b or Msx2 causes syndactyly with retained webbing and fused soft tissue. FGF8 from digit tips opposes BMP to maintain digit outgrowth and survival. SHH and PITX1 regulate patterning and hindlimb identity respectively

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 20: BMP4 essential for interdigital apoptosis.

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Limb Development -lll

Which molecule is essential for interdigital apoptosis in tetrapod limbs?

Digit separation requires selective elimination of interdigital necrotic zones by programmed cell death. BMP ligands through BMPR1A BMPR1B activate phosphorylated Smad1-5-8 cascade, transcriptionally upregulate Msx1 Msx2 and promote caspase-dependent apoptosis with DNA fragmentation. Distal FGFs from digit tips antagonize BMP to protect digit chondrogenesis driven by Sox9. In ducks, Gremlin blocks BMP and retains webbing; ectopic Noggin in chick creates syndactyly. Genetic ablation of BMP2 or BMP4 or Msx2 causes soft-tissue fusion. SHH and FGF10 promote growth, RA modulates proximal identity, but BMP4 execution is central to interdigital apoptosis forming free digits.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 20: BMP-induced interdigital apoptosis.

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