CLN8 Deficiency Impairs Dendritic Development in Hippocampal Neuronal Model

PESAOLA F; QUASSOLLO G,; NOHER DE HALAC I.; BISBAL M

Rio de Janeiro

Congreso; 13th International Congress of Inborn Errors of Metabolism; 2017

Latin American Society of Inborn Errors of Metabolism and Neonatal Screening

Introduction: CLN8-disease belongs to the group of NeuronalCeroid Lipofuscinoses, neurodegenerative disorders characterizedby the abnormal lysosomal accumulation of lipofuscinlikecompounds. It is caused by a deficiency of CLN8p, anEndoplasmic Reticulum resident protein. It was related with thesynthesis, transport and detection of lipids; however, its roleremains unknown. We aim to study the effect of CLN8 expressionlevels on the morphology of neurons. Methods: Embryonichippocampal rat neurons of 2 and 9 d.i.v. were transiently transfectedwith pYFP (control) alone or co-transfected withpCLN8wt (overexpression) or pshCLN8 (silencing). 2 d.i.v. neuronswere marked with anti-Tau and anti-Tubulin by immunostainingfor axonal length measure. 9 d.i.v. neurons were used fordendritic branching study by Sholl analysis. Images were takenin an epifluorescence microscope and analyzed with ImageJ-Fijisoftware. One-way ANOVA test was used to evaluate axonallength, and two-way ANOVA test with repeated measures wasused for dendritic evaluation. Results: 1) 2 d.i.v. neurons did notshow meaningful differences regarding axonal length amongtreatments (P > .05). 2) 9 d.i.v. neurons did reveal significantvariations in dendritic ramification measured. Dendritic developmentin pshCLN8-treated cells was diminished comparedwith control cells (P < .0001). Interestingly, neurons overexpressingCLN8 showed values between the other two conditions.Discussion: CLN8p deficiency affects dendritic development,but not the axonal length. Our previous results showed a tendencyof CLN8 to alter lysosomal distribution in the cell body.An appropriate lysosomal function and distribution are requiredfor a correct dendritic development.Moreover, it was shown thatchanges in the morphology of dendrites are related with someneurodegenerative disorders. Now we propose that both overexpressionand silencing of CLN8 affect the development ofdendrites possibly through altering lysosomal dynamics. Thesemorphological changes may be part of the pathophysiology ofCLN8, as was shown for some other neurodegenerative diseases.