Isolation and embryonic expression of avian ADAM 12 and ADAM 19

Members of the ADAM gene family encode large multi-domain proteins containing A Disintegrin And Metalloprotease domain. We have cloned quail orthologs of ADAM 12 and 19 using PCR-based screening and describe their expression patterns over the period E2.5 (Hamilton and Hamburger stage 14) to E5.0 (HH 25) using in situ hybridisation. Quail ADAM 12 is expressed in mesenchyme, cranially, in the tail and in the limb buds, and also in visceral mesenchyme. In the nervous system it is expressed in dorsal root ganglia and ventral roots. Quail ADAM 19 is expressed in cranial and dorsal root ganglia, sympathetic ganglia, ventral mixed nerves and in the allantois. Avian ADAM 12 and 19 genes exhibit similarities and differences in expression pattern compared to their murine orthologs, for example, expression of ADAM 12 in the nervous system, limb and tail bud in quail but not mouse. Interestingly, in mouse ADAM 19 is expressed in these locations. We have generated a sheep antibody to quail ADAM 19 and, in embryonic cells in vitro, found the protein at cell-cell junctions in many cell types. Some of these did have detectable ADAM 19 by in situ hybridisation but RT-PCR analysis confirmed the presence of low level ADAM 19 transcripts not detectable by in situ hybridisation.