MoD Special issue on “Upstream and Downstream of Hox Genes

The antero-posterior axis of bilaterian is determined by set of homeodomain transcription factors encoded by the hox genes that are organized into gene clusters. Remarkably, the arrangement of the hox genes along the chromosome within the cluster corresponds to the order of the structures that are specified along the antero-posterior body axis of the organism. This conserved organization is thought to reflect fundamental mechanism of activation that is conserved through evolution. Nine years back, leading scientists in this field and large number of participants gathered at Center for Cellular andMolecular Biology at Hyderabad to discuss the biology of hox genes in an EMBOworkshop entitled ‘Upstream and Downstream of Hox Genes’ (Affolter and Mann, 2006). Upstream stands mostly for the chromatin mechanism that govern hox gene regulation and that were discovered through the initial identification of the polycomb group of genes and the trithorax group of genes in Drosophila. Downstream relates to the identification of the target genes regulated by the hox proteins and that realize themorphological features that form along the antero-posterior axis. Downstream also stands for DNA target selection by the hox proteins and their cofactors. Between Upstream and Downstream, lies the study of the regulatory landscape of the hox clusters. Recently, the event was replicated and advances in thefield of hox geneswere discussed in another edition of the same workshop. It was amazing to see enormous progress in the field during these nine years aswell as the new challenges that emerged alongwith the new insights. An unique asset of themeeting is the gathering of specialists from distant horizons, such as epigeneticists, transcriptional regulation aficionados, developmental biologists and evolutionarists that rarely meet. Discussions of this hox meeting can be broadly clubbed into three groups.