Hypothesis 3265 FGD1 as a central regulator of extracellular matrix remodelling – lessons from faciogenital dysplasia Elisabeth Genot1,2,3,4, Thomas Daubon1,2,3, Vincenzo Sorrentino5 and Roberto Buccione6,* 1Universite´ de Bordeaux, Physiopathologie du Cancer du Foie, U1053, F-33000 Bordeaux, France 2INSERM, Physiopathologie du Cancer du Foie, U1053, F-33000 Bordeaux, France 3European Institute of Chemistry and Biology, 2 rue Robert Escarpit, 33607 Pessac, France 4CHU de Bordeaux, F-33076 Bordeaux, France 5Department of Neurosciences, Molecular Medicine Section, University of Siena, Siena 53100, Italy 6Tumour Cell Invasion Laboratory, Consorzio Mario Negri Sud, S. Maria Imbaro, Chieti 66030, Italy *Author for correspondence (
[email protected]) Accepted 27 March 2012 Journal of Cell Science 125, 3265–3270 ß 2012. Published by The Company of Biologists Ltd doi: 10.1242/jcs.093419 Summary Disabling mutations in the FGD1 gene cause faciogenital dysplasia (also known as Aarskog-Scott syndrome), a human X-linked developmental disorder that results in disproportionately short stature, facial, skeletal and urogenital anomalies, and in a number of cases, mild mental retardation. FGD1 encodes the guanine nucleotide exchange factor FGD1, which is specific for the Rho GTPase cell division cycle 42 (CDC42). CDC42 controls cytoskeleton-dependent membrane rearrangements, transcriptional activation, secretory membrane trafficking, G1 transition during the cell cycle and tumorigenic transformation. The cellular mechanisms by which FGD1 mutations lead to the hallmark skeletal deformations of faciogenital dysplasia remain unclear, but the pathology of the disease, as well as some recent discoveries, clearly show that the protein is involved in the regulation of bone development. Two recent studies unveiled new potential functions of FGD1, in particular, its involvement in the regulation of the formation and function of invadopodia and podosomes, which are cellular structures devoted to degradation of the extracellular matrix in tumour and endothelial cells.