TIN has recently engaged the laboratory of Mario Bortolozzi at the Veneto Institute of Molecular Medicine in a new sponsored research project. This project is aimed at directly linking genetic defects of CMT1X patients, with dysfunction of the protein that is produced by the disease gene.
CMT1X is caused by the inheritance of a gene (gjb1) that has errors in the instructions it carries to guide the production of a protein called Connexin-32. A normal Connexin-32 protein is located at the surface of a Schwann cell, and acts as a portal into the cell, gating the entry and exit of molecules required for cellular function. In many CMT1X patients, Connexin-32 is present at the cell surface, but is defective in its ability to normally open or close the “gate” that it forms there.
The Bortolozzi laboratory has shown that it can insert the gjb1 gene, or mutant forms of it, directly into a cell, and record the activity of the Connexin-32 gate as it opens and closes. This measure of Connexin-32 function in a dish was used by the laboratory to show how a mutant protein characteristically differs in its opening and closing at the surface of a cell from a normal Connexin-32 protein.
The main goals of the sponsored project are two-fold:
First, the Bortolozzi laboratory will extend their previous work by showing that multiple human mutations of gjb1, which are representative of different CMT1X patients, produce a similar and measurable dysfunction in the portal formed by Connexin-32. This will immediately enable a test in a dish, which can be used routinely to evaluate potential therapies on a lab bench. This would greatly increase the speed, and lower the cost, at which new ideas for therapies can be initially evaluated, before testing in an animal model.
Secondly, the test assay once established will be used to evaluate a potential therapy approach in the laboratory. There is presently evidence that a protein that is known to be “druggable” can interact with Connexin-32 and control its gating function. This potential drug target for CMT1X will be expressed in cells together with the disease gene. Drug-like tools are already available that can turn on this target, and these will be used to show reversal of the dysfunction of the mutant Connexin-32. Success in this arm of the sponsored research would lead to the rapid development of a therapy approach that can be brought to patients.