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Neuroscience Journal
Volume 2016, Article ID 4732837, 8 pages
http://dx.doi.org/10.1155/2016/4732837
Research Article

Transcription Factor EB Is Selectively Reduced in the Nuclear Fractions of Alzheimer’s and Amyotrophic Lateral Sclerosis Brains

1Section of Neurobiology, Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, FL 34987, USA
2Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA

Received 20 April 2016; Revised 3 June 2016; Accepted 7 June 2016

Academic Editor: Inga Kadish

Copyright © 2016 Hongjie Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Multiple studies suggest that autophagy is strongly dysregulated in Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS), as evidenced by accumulation of numerous autophagosomes, lysosomes with discontinuous membranes, and aggregated proteins in the patients’ brains. Transcription factor EB (TFEB) was recently discovered to be a master regulator of lysosome biogenesis and autophagy. To examine whether aberrant autophagy in AD and ALS is due to alterations in TFEB expression, we systematically quantified the levels of TFEB in these brains by immunoblotting. Interestingly, cytoplasmic fractions of AD brains showed increased levels of normalized (to tubulin) TFEB only at Braak stage IV (61%, ). Most importantly, normalized (to lamin) TFEB levels in the nuclear fractions were consistently reduced starting from Braak stage IV (52%, ), stage V (67%, ), and stage VI (85%, ) when compared to normal control (NC) brains. In the ALS brains also, nuclear TFEB levels were reduced by 62% (). These data suggest that nuclear TFEB is selectively lost in ALS as well as AD brains, in which TFEB reduction was Braak-stage-dependent. Taken together, the observed reductions in TFEB protein levels may be responsible for the widely reported autophagy defects in these disorders.