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Updated: May 6, 2026

A Rapid In Vivo Bioassay for Developmentally Active Enhancers
Hox5 interacts with Plzf to restrict Shh expression in the developing forelimb.
Ben Xu1, Steven M Hrycaj, Daniel C McIntyre
1Department of Internal Medicine, Division of Molecular Medicine and Genetics, University of Michigan, Ann Arbor, MI 48109.
Anterior Hox5 genes are crucial for proper forelimb development by repressing Sonic Hedgehog (Shh) expression. Loss of Hox5 genes leads to anterior limb defects due to Shh derepression, revealing novel roles in limb patterning.
Area of Science:
- Developmental Biology
- Genetics
- Molecular Biology
Background:
- Hox genes (Hox9-Hox13) are known to regulate posterior limb patterning.
- Posterior Hox genes control proximodistal skeletal elements and initiate Hand2 and maintain Sonic Hedgehog (Shh) expression.
Purpose of the Study:
- To investigate the role of anterior Hox paralog groups in forelimb patterning.
- To determine the function of Hox5 genes in vertebrate limb development.
Main Methods:
- Gene deletion of all three Hox5 genes (Hoxa5, Hoxb5, Hoxc5).
- Analysis of forelimb anterior patterning defects.
- Biochemical and genetic interaction studies with promyelocytic leukemia zinc finger.
- Examination of Sonic Hedgehog (Shh) expression levels.
Main Results:
- Deletion of all Hox5 genes caused anterior forelimb defects.
- These defects were linked to the derepression of Shh expression.
- Hox5 genes function redundantly and interact with promyelocytic leukemia zinc finger to restrict Shh expression.
Conclusions:
- Anterior Hox5 genes are essential for forelimb anterior patterning.
- Repression of Shh expression by Hox5 is critical for correct vertebrate limb development.
- Highlights the importance of Shh regulation in limb patterning.
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