Molecular analysis of Aldh1a2 conditional inactivation in developing limbs reveals mechanisms of retinoic-acid mediated interdigital apoptosis

In particular, RA function during limb development is associated with interdigital cell death. However, the molecular mechanism(s) through which RA signaling contributes to interdigital cell death remains elusive.

To gain insights into the mechanism(s) involved, we used a conditional approach to inactivate the RA catalyzing enzyme Aldh1a2 thereby abrogating RA signaling in the distal limb. Our data first show that Aldh1a2 mutant limb buds are characterized by a lack of apoptosis in the interdigital region, which results in a very severe syndactyly phenotype at birth. Molecular analysis of Aldh1a2 mutant distal limb buds reveals that RA regulates the expression of several key genes in the interdigital tissue related to apoptosis in the limb and to the extracellular matrix degradation.