CLN8 interactors: a possible function of the CLN8 protein in the lipid metabolism and autophagy

e NCLs are a group of neurodegenerative lysosomal storage diseases mainly occurring in childhood. ey are characterized by lipopigment inclusions and visual loss, motor and cognitive dysfunction and epilepsy. Diagnosis relays upon the identification of mutations of at least ten genes (CLN1-CLN10), leading to distinct forms. Pathogenic mechanisms are still unknown and no cure is available. We have recently showed that in the mnd (motor neuron disease) mouse, which is a model of the CLN8 form of the late-infantile NCL (CLN8-vLINCL), oxidative stress, lipid peroxidation, inflammation and ER stress occur in certain neuronal types and are likely associated to autophagy and mitochondrial dysfunction in the progression of the disease (Guarneri et al., 2004; Galizzi et al., 2011). e CLN8 gene encodes a transmembrane protein with unknown function that is located at ER and Golgi compartment. Due to the high homology with the TCL-domain (TRAM- LAG1- CLN8), the CLN8 protein is presumed to be involved in the lipid synthesis and transport (Winter and Ponting, 2002). Here, by screening a human adult brain cDNAs library using the yeast twohybrid split ubiquitin system, we identified interesting binding partners of the CLN8, such as the VAP-A protein, which is involved in the lipid synthesis and transport, and three other proteins - GABARAPL2, BNIP3 and BNIP3L - that belong to the autophagic pathway. ese interactions were confirmed by coimmunoprecipitation and co-localization studies using Cos-1 and Hela cells transiently transfected. Our findings highlight the potential function of the CLN8 in the lipid homeostasis and endosomal-lysosomal pathway and provide clues to understanding the pathomechanism(s) of the CLN8-vLINCL.