Consequences of Dynamin 2 PH Domain Dysfunction in Charcot-Marie-Tooth Neuropathy

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Our team has just discovered a new gene mutation that causes Charcot-Marie-Tooth (CMT) disease. CMT is a clinically and genetically diverse family of human peripheral neuropathies. CMT neuropathy is the most common inherited peripheral neuropathy, affecting approximately 1 in 2500. It is the most common human genetic disorder known and is caused by fifty or more genes. CMT is of large economic significance since many of the affected individuals are on lifetime invalid pensions and require continual medical and paramedical support. The new mutation we discovered is in a variant form of CMT and affects the protein dynamin 2, in an important region called the PH domain. The normal function of Dyn2 is to retrieve activated receptors for hormones and growth factors from the membrane of cells (caller receptor mediated endocytosis or RME) and it is also required for other functions like cell proliferation. The PH domain is the part of Dyn2 that allows it to move to the appropriate part of the cell when needed to do its job, but it is not known whether the mutation disrupts this function of Dyn2. Since Dyn2 has multiple cellular functions, it is not understood why it might cause the disease. Our goal is to understand why this mutation causes peripheral nerves to degenerate, by revealing which of dynamin's many functions are primarily affected. We expect to uncover a new concept in how RME links to neuronal degeneration. In previous studies we developed the first drugs that interact with PH domains. We will now fully develop these, and synthesise new drugs that interact with the PH domain, as candidates to effect some repair of the damaged PH domain. A better understanding of Dyn2 and endocytosis is crucial to understanding both CMT and ultimately for developing therapies.