A novel first exon of the Patched1 gene is upregulated by Hedgehog signaling resulting in a protein with pathway inhibitory functions

Patched homolog 1 (PTCH1) is a key component of the Hedgehog (HH) signaling pathway with three alternative first exons, but only exon 1B transcription depending on HH activation. Here, we show that in both human and mouse a novel PTCH1 first exon (1C) is expressed. Exon 1C transcription is upregulated by HH signaling, but the resulting PTCH1-1C protein has a lower capacity for pathway inhibition than PTCH1-1B.