Lysosomes can be thought of as the 'garbage-disposal units' of our cells, including cells of the retina and brain. The CLN3 protein is located in the membrane surrounding the lysosome and is known as a 'transmembrane' protein. While the function of the CLN3 protein in cells is not fully understood, we do know it has important functions related to degradation of cell waste and transport of cellular cargo in and out of the lysosome.
The Nature paper, published by Laqtom and colleagues, reveals that in mice with a defective CLN3 gene (and dysfunctional CLN3 protein), a specific cellular waste product called glycerophosphodiesters, or GPDs, accumulate in massive, toxic levels inside lysosomes . GPDs are a naturally occuring breakdown product of fatty membrane proteins called glycerophospholipids. The study reveals for the first time that functional CLN3 protein is required for the efflux of GPDs from the lysosome, and identifies a key pathway in CLN3 disease that may prove a useful target in the development of effective therapies.