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#BMP

2 public questions tagged with this topic.

Limb Development -l

Which molecule acts as an inhibitor of BMP signaling in limb development?

Bone morphogenetic protein activity must be spatially modulated to permit cartilage condensation and prevent premature apoptosis. Noggin is secreted extracellular antagonist binding BMP2, BMP4, BMP7 with high affinity, preventing ligand binding to receptors and Smad activation. Expression of Noggin in distal mesenchyme allows chondrogenic differentiation and maintains FGF signaling loop through Gremlin-family related inhibition. Wnt7a dorsalizes limb, FGF10 induces bud, Tbx5 specifies forelimb. Balanced BMP-Noggin interplay regulates joint formation, digit number, and interdigital regression essential for sculpted limb morphology and digit separation.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 19: BMP antagonists Noggin and Gremlin in limb patterning.

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frog development

High levels of BMP specify amphibian ectodermal cells to become:

BMP morphogen gradient patterns ectoderm: highest ventrally, lowest dorsally. High BMP4/7 activates Smad1/5/8 complexing with Smad4, translocating to nucleus inducing epidermal keratin genes XK81, AP2 and GATA2 while repressing Sox2 and Neurogenin. Animal caps exposed to BMP become ciliated epidermis. In intact embryo lateral and ventral ectoderm receiving high BMP becomes epidermis covering embryo, dorsal ectoderm protected by organizer antagonists becomes neural plate. Neural crest forms at intermediate BMP border. Thus high BMP specifies epidermis rather than neural, crest or endoderm fates. This illustrates conserved developmental logic of morphogen gradients patterning embryonic axes through Wnt and BMP antagonism.

Ref: Gilbert, Developmental Biology 12th ed., Chapter 12: BMP gradient and ectodermal patterning.

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