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

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 TFEBexpression, we systematically quantified the levels of TFEBin these brains by immunoblotting. Interestingly, cytoplasmic fractions of AD brains showed increased levels of normalized (to tubulin) TFEBonly at Braak stageIV (61%, ). Most importantly, normalized (to lamin) TFEBlevels in the nuclear fractions were consistently reduced starting from Braak stageIV (52%, ), stage V (67%, ), and stage VI (85%, ) when compared to normal control (NC) brains. In the ALS brains also, nuclear TFEBlevels were reduced by 62% (). These data suggest that nuclear TFEBis selectively lost in ALS as well as AD brains, in which TFEBreduction was Braak-stage-dependent. Taken together, the observed reductions in TFEBprotein levels may be responsible for the widely reported autophagy defects in these disorders.