Broad-spectrum rescue-of-secretion of Tdark glycoprotein mutants

This project has been funded thanks to the Joint Call Fondazione Cariplo and Fondazione Telethon 2022

Proteins - large molecules central to life - adopt a specific shape to perform their activities. This process is called folding and, for some proteins, it happens in a cell organelle called Endoplasmic Reticulum (ER).

In the ER, a wonderfully efficient machinery retains newly made proteins until they are folded properly. This quality control is of great help to healthy people, but in individuals carrying a DNA mutation in a secreted protein gene, the same system causes disease.

What happens in these patients is that the quality control system recognises a defect in a mutated protein, which then remains stuck in the ER, even if the defect is small and the patient would still profit from the protein’s exit from the ER, because of its residual activity (“responsive mutant”). Terrible disease ensues.

We shall study in the laboratorywhat the quality control does to such responsive mutants, following their trajectories in human cells in which the quality control checkpoint has been deleted. If, in these conditions, the responsive mutant can escape the ER, then a drug that loosens the same checkpoint should have therapeutic potential in a broad range of rare diseases.

We selected a panel of ten such defective proteins, hand-picked from the set of 6,000 or so human proteins whose function is little or completely unknown (“Tdark proteins”). This choice has the additional advantage that we shall contribute basic knowledge about Tdarks, towards future treatment of patients whose rare disease is presently not understood let alone cured.