Distal Limb Patterning Requires Modulation of cis-Regulatory Activities by HOX13

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• Hox genes establish positional identity along the animal body axis.
• HOXA13 and HOXD13 (HOX13) transcription factors are essential for digit development, but their regulatory mechanisms are unclear.

Purpose of the Study:

• To investigate the genome-wide binding of HOXA13 and HOXD13 in vivo.
• To understand how HOX13 proteins regulate gene expression and chromatin state during distal limb development.

Main Methods:

• Genome-wide profiling of HOXA13 and HOXD13 binding.
• Transcriptome and chromatin state analysis in wild-type and HOX13-deficient mouse limbs.
• Analysis of cis-regulatory module activity.

Main Results:

• HOX13 proteins bind to specific cis-regulatory modules in the developing limb.
• HOX13 regulates the transition from early to late distal limb developmental programs.
• Loss of HOX13 disrupts gene expression and chromatin accessibility, impacting limb formation.

Conclusions:

• HOX13 proteins coordinate the termination of the early limb program and activation of the late-distal limb program.
• The dual action of HOX13 on cis-regulatory modules is critical for distal limb identity and development.