Novel clathrin activity: developments in health and disease

Clathrin self-assembles into a coat around vesicles filled with cargo such as nutrients, hormones, and proteins destined for degradation. Recent developments indicate clathrin is not a specialist, but is involved in different processes relevant to health and disease. Clathrin is used to strengthen centrosomes and mitotic spindles essential for chromosome segregation in cell division. In Wnt signaling, clathrin is a component of signalosomes on the plasma membrane needed to produce functional Wnt receptors. In glucose metabolism, a muscle-specific isoform, CHC22 clathrin, is key to the formation of storage compartments for GLUT4 receptor, and CHC22 dysfunction has been tied to type 2 diabetes. The activity of clathrin to self-assemble and to work with huntingtin-interacting proteins to organize actin is exploited by Listeria and enteropathic Escherichia coli in their infection pathways. Finally, there is an important connection between clathrin and human malignancies. Clathrin is argued to help transactivate tumor suppressor p53 that controls specific genes in DNA repair and apoptosis. However, this is debatable because trimeric clathrin must be made monomeric. To get insight on how the clathrin structure could be converted, the crystal structure of the trimerization domain is used in the development of the detrimerization switch hypothesis. This novel hypothesis will be relevant if connections continue to be found between CHC17 and p53 anti-cancer activity in the nucleus.