PSENEN/PEN2 is the smallest subunit of the γ-secretase complex, an intramembrane protease that cleaves proteins within their transmembrane domains. Mutations in components of the γ-secretase underlie Show more
PSENEN/PEN2 is the smallest subunit of the γ-secretase complex, an intramembrane protease that cleaves proteins within their transmembrane domains. Mutations in components of the γ-secretase underlie familial Alzheimer disease. In addition to its proteolytic activity, supplementary, γ-secretase independent, functions in the macroautophagy/autophagy-lysosome system have been proposed. Here, we screened for PSENEN-interacting proteins and identified CLN3. Mutations in Show less
Juvenile neuronal ceroid lipofuscinosis, the most common neurodegenerative disease affecting children, is caused by mutations of the CLN3 gene encoding CLN3, a transmembrane protein with so far undefi Show more
Juvenile neuronal ceroid lipofuscinosis, the most common neurodegenerative disease affecting children, is caused by mutations of the CLN3 gene encoding CLN3, a transmembrane protein with so far undefined function. The embryonic expression of the gene has not been studied in detail before. Moreover, the protein CLN3 was mostly localized on the subcellular level to lysosomes but the exclusiveness is still under debate. Here, we analyze the expression pattern of murine CLN3 at different developmental stages by in situ hybridizations. We observe expression maxima in the developing thalamus and cerebral cortex and outside of the central nervous system in the gastrointestinal tract and other peripheral organs. In differentiated primary neurons, the protein CLN3 shows mainly a somatodendritic localization. In primary neurons, we thoroughly revisit the subcellular localization of CLN3 and find a predominant localization in late endosomal-lysosomal compartments. Moreover, we expressed the major mutant form of CLN3 - CLN3deltaExon7/8 - in neurons and demonstrate that it is retained in the endoplasmatic reticulum. Time-lapse microscopy analysis of neurons revealed co-trafficking of CLN3 with the late endosomal marker Rab7, but not with the early endosomal marker Rab5. Furthermore, a constitutive active mutant of Rab7 traps CLN3 in enlarged endosomes. Our subcellular localization study in neurons refines the localization and subcellular targeting of CLN3 to late endosomal-lysosomal compartments and provides information on the velocity of CLN3 in living neurons which has not been investigated before. Show less