Dr Virginie Hamel and A/Prof Paul Guichard

Swiss researchers have identified the essential role of four proteins in retinitis pigmentosa (RP), which could help prevent photoreceptor death, they said.  

Describing the proteins as a ‘molecular zipper’, lead authors Associate Professor Paul Guichard and Dr Virginie Hamel, University of Geneva, said mutations in the genes encoding the proteins are associated with retinal pathologies leading to photoreceptor degeneration. The proteins are located in the cilium that connects the outer and inner segments of retinal neuronal cells. “In the centriole, these proteins ensure the cohesion of the different microtubules by acting like a zipper. We wondered if they did not play the same role in the tubular structures of the connecting cilium,” explained Dr Hamel. 

The authors described visualising retinal tissue with increased resolution via a pioneering expansion microscopy technique that allowed cells to be inflated without deforming them. Using a mouse model, they observed that intact proteins ensured cohesion between microtubules by forming a ‘zipper’ that closed as development proceeded. With mutations affecting those proteins, however, adult mice microtubules eventually collapsed, leading to photoreceptor death. 

“By injecting the (intact) protein into patients suffering from certain types of retinitis pigmentosa, we can imagine preventing the death of photoreceptor cells,” said A/Prof Guichard.