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

Wang H, Wang R, Xu S, Lakshmana MK - Neurosci J (2016)

Bottom Line: Most importantly, normalized (to lamin) TFEB levels in the nuclear fractions were consistently reduced starting from Braak stage IV (52%, p < 0.01), stage V (67%, p < 0.01), and stage VI (85%, p < 0.01) when compared to normal control (NC) brains.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.

View Article: PubMed Central - PubMed

Affiliation: Section of Neurobiology, Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, FL 34987, USA.

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%, p < 0.01). Most importantly, normalized (to lamin) TFEB levels in the nuclear fractions were consistently reduced starting from Braak stage IV (52%, p < 0.01), stage V (67%, p < 0.01), and stage VI (85%, p < 0.01) when compared to normal control (NC) brains. In the ALS brains also, nuclear TFEB levels were reduced by 62% (p < 0.001). 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.

No MeSH data available.


Related in: MedlinePlus

Reduced expression of TFEB protein in ALS nuclear fractions. Lysates of patients brains diagnosed with ALS and NC were prepared, and nuclear and cytosolic fractions were separated as in Figures 1 and 2. Actin and lamin were detected as loading controls and used for normalization of TFEB protein levels. Quantitation by ImageJ revealed significantly reduced (62%) normalized (to lamin) levels of TFEB protein in the nuclear fractions, but no change in the cytosolic fractions. The data are mean ± SEM. ∗∗∗p < 0.001 by Student's paired t-test, n = 5 per group.
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fig3: Reduced expression of TFEB protein in ALS nuclear fractions. Lysates of patients brains diagnosed with ALS and NC were prepared, and nuclear and cytosolic fractions were separated as in Figures 1 and 2. Actin and lamin were detected as loading controls and used for normalization of TFEB protein levels. Quantitation by ImageJ revealed significantly reduced (62%) normalized (to lamin) levels of TFEB protein in the nuclear fractions, but no change in the cytosolic fractions. The data are mean ± SEM. ∗∗∗p < 0.001 by Student's paired t-test, n = 5 per group.

Mentions: Since autophagy is also dysregulated in ALS brains [22–24], we obtained ALS and NC brains from NICHD. The demographic details of NC and ALS patients are given in Table 2. The age range of NC subjects was 59–76 years and the PMI was between 3 and 21 h. For ALS patients, the age range was 59–87 years and the PMI were 6–22 h. Both males and females were included in the NC and ALS groups. The motor cortices were subjected to homogenization and separated into nuclear and cytoplasmic fractions as described above for AD brains. Immunoblot detection and quantitation of TFEB protein levels in the cytoplasmic fractions did not reveal any changes in the ALS motor cortex compared to NC. However, nuclear fractions showed a 62% reduction (p < 0.001) compared to NC motor cortex (Figure 3). Thus, similar to AD brains, reduction in nuclear TFEB levels in ALS brains suggests possible reduction in TFEB's transcriptional activity.


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

Wang H, Wang R, Xu S, Lakshmana MK - Neurosci J (2016)

Reduced expression of TFEB protein in ALS nuclear fractions. Lysates of patients brains diagnosed with ALS and NC were prepared, and nuclear and cytosolic fractions were separated as in Figures 1 and 2. Actin and lamin were detected as loading controls and used for normalization of TFEB protein levels. Quantitation by ImageJ revealed significantly reduced (62%) normalized (to lamin) levels of TFEB protein in the nuclear fractions, but no change in the cytosolic fractions. The data are mean ± SEM. ∗∗∗p < 0.001 by Student's paired t-test, n = 5 per group.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig3: Reduced expression of TFEB protein in ALS nuclear fractions. Lysates of patients brains diagnosed with ALS and NC were prepared, and nuclear and cytosolic fractions were separated as in Figures 1 and 2. Actin and lamin were detected as loading controls and used for normalization of TFEB protein levels. Quantitation by ImageJ revealed significantly reduced (62%) normalized (to lamin) levels of TFEB protein in the nuclear fractions, but no change in the cytosolic fractions. The data are mean ± SEM. ∗∗∗p < 0.001 by Student's paired t-test, n = 5 per group.
Mentions: Since autophagy is also dysregulated in ALS brains [22–24], we obtained ALS and NC brains from NICHD. The demographic details of NC and ALS patients are given in Table 2. The age range of NC subjects was 59–76 years and the PMI was between 3 and 21 h. For ALS patients, the age range was 59–87 years and the PMI were 6–22 h. Both males and females were included in the NC and ALS groups. The motor cortices were subjected to homogenization and separated into nuclear and cytoplasmic fractions as described above for AD brains. Immunoblot detection and quantitation of TFEB protein levels in the cytoplasmic fractions did not reveal any changes in the ALS motor cortex compared to NC. However, nuclear fractions showed a 62% reduction (p < 0.001) compared to NC motor cortex (Figure 3). Thus, similar to AD brains, reduction in nuclear TFEB levels in ALS brains suggests possible reduction in TFEB's transcriptional activity.

Bottom Line: Most importantly, normalized (to lamin) TFEB levels in the nuclear fractions were consistently reduced starting from Braak stage IV (52%, p < 0.01), stage V (67%, p < 0.01), and stage VI (85%, p < 0.01) when compared to normal control (NC) brains.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.

View Article: PubMed Central - PubMed

Affiliation: Section of Neurobiology, Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, FL 34987, USA.

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%, p < 0.01). Most importantly, normalized (to lamin) TFEB levels in the nuclear fractions were consistently reduced starting from Braak stage IV (52%, p < 0.01), stage V (67%, p < 0.01), and stage VI (85%, p < 0.01) when compared to normal control (NC) brains. In the ALS brains also, nuclear TFEB levels were reduced by 62% (p < 0.001). 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.

No MeSH data available.


Related in: MedlinePlus