International Mammalian Genome Society

G27 Regulated Expression of Patched (Ptc1 and Ptc2) and Sonic Hedgehog Signalling During Somite Formation in Mouse Embryos

Evi Wollscheid, Anne-Gaelle Borycki, Adonia Hsu, Charles P. Emerson. Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia PA 19104-6058., USA

Sonic hedgehog (Shh), a secreted signaling protein produced by the notochord and floorplate, is an essential signal for the activation of the myogenic regulatory gene, Myf5, during somite formation in vertebrate embryoss. In order to investigate the mechanisms that regulate Shh signaling and Myf5 activation in somites, we have examined the developmental regulation of the Shh receptor genes,

Patched 1 and Patched 2 (Ptc1 and Ptc2) using in situ hybridization techniques. We have found that in tight coordination with somite formation.. Ptc1 is expressed preferentially in the dorsal medial somite in the region of Myf5 activation and myotome differentiation, whereas Ptc2 is expressed preferentially in the ventral somite in the region of sclerotome formation. These findings indicate that Ptc regulates Shh signaling during somite formation and that Ptc1 and Ptc2 have differential functions in the Shh signaling regulation of myotome and sclerotome formation. Experiments are in progress to investigate the roles of specific Gli transcription factors in the somite expression of Ptc genes.

Supported by NIH and March of Dimes.