Fibrillar Collagen Genes

Abstract

The collagens represent a multigene family whose members are segregated into evolutionarily distinct groups. The largest of these groups (group 1) includes the genes that specify the procollagen precursors of the fibril-forming molecules (types I, 11, 111, V, and XI). To date seven of the group 1 genes have been cloned, and their corresponding loci have been mapped. Despite some important differences, the overall organization of the fibrillar collagen genes is highly similar and remarkably conserved in Deuterostomia. This substantiates the hypothesis that the group 1 collagens arose from a common multi-exon progenitor prior to vertebrates’ radiation. The characterization of several collagenopathies has elucidated some of the selective pressures that have rigidly maintained such a complex organization during evolution. These studies have also defined the metabolic consequences of collagen mutations and the unique contribution of each collagen type to the integrity of the body architecture. In contrast to their structural similarities, the differential expression of the group 1 genes correlates with the presence of distinct networks of interactions between cisacting sequences, as well as between these elements and specific trans-acting nuclear factors. Relevant to this, the finding that fibrillar collagen genes are activated during