Abstract Details

Title Failure of Autolysosome Fusion Results in Impaired Autophagy in UBQLN2-Linked ALS-FTD

Topic Anterior Horn

Presentation(s) P02 - (-)

Poster/Presentation
Number 167

Objective

Background BACKGROUND: Mutations in UBQLN2 cause ALS and ALS-FTD. Pathological inclusions containing UBQLN2 are a common pathological feature in ALS and ALS-FTD. UBQLN2 sits at the crossroads of protein degradation through the ubiquitin-proteasome system (UPS), and bulk lysosomal degradation via autophagy. Alterations in autophagy have been proposed to contribute to pathogenesis in several neurodegenerative diseases including ALS. However, the precise mechanism behind autophagy malfunction in ALS is poorly understood.

Design/Methods DESIGN/METHODS: To study the effect of UBQLN2 mutations on autophagy, neuro-2a cells were transiently transfected with expression vectors containing wildtype (wt) UBQLN2, P497H-UBQLN2 or P506T-UBQLN2. For flow cytometry and imaging studies, cells were co-transfected with an autophagosome marker (LC3-GFP). Fourty-eight hours post-transfection cells were collected using a BD LSRFortessa flow cytometer and analyzed using BD FACSDiva software. For imaging studies, cells were fixed 24 hours post-transfection, immunolabeled with anti-UBQLN2, anti-p62 or anti-LAMP1 antibodies and analyzed using a Zeiss LSM 510 Meta laser scanning confocal microscope. Endogenous LC3 and p62 turnover assay was performed using Western blotting according to standard protocols.

Results RESULTS: We found that cells expressing mutant UBQLN2 accumulate autophagosomes and autophagosome precursors. Expression of mutant UBQLN2 leads to an accumulation of autophagosome-associated proteins, LC3 and p62. After autophagic induction, autophagosomes in mutant UBQLN2 expressing cells fail to mature into autolysosomes and degrade LC3 and p62.

Conclusions CONCLUSIONS: Our data implicate UBQLN2 in autophagy, and suggest that impaired autophagy due to the failure of autolysosome fusion is central to the pathogenesis of UBQLN2-linked ALS and ALS-FTD and may explain the pathology seen in ALS and FTD patients. Hence, autophagy represents an attractive target for designing rational therapeutics in ALS and FTD.

Authors/Disclosures
Faisal Fecto, MD, PhD (Advocate Medical Group) PRESENTER	The institution of Dr. Fecto has received research support from NINDS.
Jacqueline A. Nicholas, MD (OhioHealth Riverside Methodist Hospital)	Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novartis. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Genentech. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bristol Myers Squib. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EMD Serono. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Greenwich Biosciences. Dr. Nicholas has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Nicholas has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for EMD Serono. Dr. Nicholas has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Genentech. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Alexion. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Vielo Bio. Dr. Nicholas has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bristol Myers Squibb. The institution of Dr. Nicholas has received research support from Novartis. The institution of Dr. Nicholas has received research support from Biogen. The institution of Dr. Nicholas has received research support from Genentech. The institution of Dr. Nicholas has received research support from PCORI. Dr. Nicholas has a non-compensated relationship as a Physician with National MS Society that is relevant to AAN interests or activities. Dr. Nicholas has a non-compensated relationship as a Physician with Siegal Rare Neuroimmune Association that is relevant to AAN interests or activities.
	No disclosure on file
Han-Xiang Deng, MD	Dr. Deng has nothing to disclose.
Teepu Siddique, MD, FAAN	No disclosure on file

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