40 years of the homeobox: mechanisms of Hox spatial-temporal collinearity in vertebrates.

Animal body plans are established during embryonic development by the Hox genes. This patterning process relies on the differential expression of Hox genes along the head-to-tail axis. Hox spatial collinearity refers to the relationship between the organization of Hox genes in clusters and the differential Hox expression, whereby the relative order of the Hox genes within a cluster mirrors the spatial sequence of expression in the developing embryo.

The pioneering function of the hox transcription factors.

Ever since the discovery that the Hox family of transcription factors establish morphological diversity in the developing embryo, major efforts have been directed towards understanding Hox-dependent patterning. This has led to important discoveries, notably on the mechanisms underlying the collinear expression of Hox genes and Hox binding specificity. More recently, several studies have provided evidence that Hox factors have the capacity to bind their targets in an inaccessible chromatin context and trigger the switch to an accessible, transcriptional permissive, chromatin state.

Cell-specific alterations in Pitx1 regulatory landscape activation caused by the loss of a single enhancer.

Developmental genes are frequently controlled by multiple enhancers sharing similar specificities. As a result, deletions of such regulatory elements have often failed to reveal their full function. Here, we use the Pitx1 testbed locus to characterize in detail the regulatory and cellular identity alterations following the deletion of one of its enhancers (Pen).