Limits...
Nuclear accumulation of HDAC4 in ATM deficiency promotes neurodegeneration in ataxia telangiectasia.

Li J, Chen J, Ricupero CL, Hart RP, Schwartz MS, Kusnecov A, Herrup K - Nat. Med. (2012)

Bottom Line: To remain cytoplasmic, HDAC4 must be phosphorylated.The activity of the HDAC4 phosphatase, protein phosphatase 2A (PP2A), is downregulated by ATM-mediated phosphorylation.In ATM deficiency, enhanced PP2A activity leads to HDAC4 dephosphorylation and the nuclear accumulation of HDAC4.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Neuroscience, Nelson Biological Laboratories, Rutgers University, Piscataway, New Jersey, USA.

ABSTRACT
Ataxia telangiectasia is a neurodegenerative disease caused by mutation of the Atm gene. Here we report that ataxia telangiectasia mutated (ATM) deficiency causes nuclear accumulation of histone deacetylase 4 (HDAC4) in neurons and promotes neurodegeneration. Nuclear HDAC4 binds to chromatin, as well as to myocyte enhancer factor 2A (MEF2A) and cAMP-responsive element binding protein (CREB), leading to histone deacetylation and altered neuronal gene expression. Blocking either HDAC4 activity or its nuclear accumulation blunts these neurodegenerative changes and rescues several behavioral abnormalities of ATM-deficient mice. Full rescue of the neurodegeneration, however, also requires the presence of HDAC4 in the cytoplasm, suggesting that the ataxia telangiectasia phenotype results both from a loss of cytoplasmic HDAC4 as well as its nuclear accumulation. To remain cytoplasmic, HDAC4 must be phosphorylated. The activity of the HDAC4 phosphatase, protein phosphatase 2A (PP2A), is downregulated by ATM-mediated phosphorylation. In ATM deficiency, enhanced PP2A activity leads to HDAC4 dephosphorylation and the nuclear accumulation of HDAC4. Our results define a crucial role of the cellular localization of HDAC4 in the events leading to ataxia telangiectasia neurodegeneration.

Show MeSH

Related in: MedlinePlus

Nuclear accumulation HDAC4 leads to global effects on histone acetylation and neuronal gene expressiona) Fluorescent images of Atm+/+ and Atm−/− cerebellum sections immunostained for different histones and acetylated histones as indicated.b) Protein extracts of cortex and cerebellum from wild-type and Atm−/− mice were probed with various histone antibodies as labeled to the left of the gels.c-d) Quantification of 3 repetitions of the experiment illustrated in panel I. Error bars denotes standard deviations. * = p<0.05 (by Student’s T-test).e-g) Fragmented chromatin was immunoprecipitated with the antibodies indicated and quantified with real-time PCR. The primers used for q-PCR are listed in Table S1. Statistical analysis was carried out using Student’s t test. Error bars represent SEMh) An illustration of the HDAC4 ChIP-seq alignment and peaks. A 2.7 Mb sample region of chromosome 1 shows the density of coverage of 35 nt sequencing tags from input DNA or ChIP from wild type (blue) or Atm−/− (red) mouse brain.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3378917&req=5

Figure 2: Nuclear accumulation HDAC4 leads to global effects on histone acetylation and neuronal gene expressiona) Fluorescent images of Atm+/+ and Atm−/− cerebellum sections immunostained for different histones and acetylated histones as indicated.b) Protein extracts of cortex and cerebellum from wild-type and Atm−/− mice were probed with various histone antibodies as labeled to the left of the gels.c-d) Quantification of 3 repetitions of the experiment illustrated in panel I. Error bars denotes standard deviations. * = p<0.05 (by Student’s T-test).e-g) Fragmented chromatin was immunoprecipitated with the antibodies indicated and quantified with real-time PCR. The primers used for q-PCR are listed in Table S1. Statistical analysis was carried out using Student’s t test. Error bars represent SEMh) An illustration of the HDAC4 ChIP-seq alignment and peaks. A 2.7 Mb sample region of chromosome 1 shows the density of coverage of 35 nt sequencing tags from input DNA or ChIP from wild type (blue) or Atm−/− (red) mouse brain.

Mentions: Enhanced HDAC4 in Atm−/− neuronal nuclei suggests a reduction of histone acetylation in these cells. Immunostaining for total histone 3 (H3) and 4 (H4) of Atm−/− cerebellum was similar to that of wild-type (Fig. 2a). By contrast, reduced immunostaining for acetylated histone 3 (AcH3) and 4 (AcH4) were found in Atm−/− neocortex and hippocampus (data not shown). These findings were confirmed by Western blots (Fig. 2b-d). We then examined the association of AcH3 and AcH4 with specific gene promoters. ChIP followed by qPCR assays was performed with extracts of wild-type and Atm−/− mouse cerebellum (Fig. 2e-g). H3 ChIP revealed no consistent difference between wild-type and Atm−/− samples in chromatin association at the promoters we examined (Fig. 2e). By contrast, the association of AcH3 and AcH4 with multiple neuronal growth genes was consistently decreased in Atm−/−. The loss of histone acetylation in a promoter region suggests a closed chromatin configuration and reduced transcription. As predicted, in Atm−/− samples, we observed decreased transcription of multiple neuronal genes at which promoter occupancy by acetylated histones was reduced, e.g., Bdnf, NR2a and Nrxn (Fig. 2f-g). Their occupancy by H3 (Fig. 2e) and H4 (not shown) were equivalent to wild-type.


Nuclear accumulation of HDAC4 in ATM deficiency promotes neurodegeneration in ataxia telangiectasia.

Li J, Chen J, Ricupero CL, Hart RP, Schwartz MS, Kusnecov A, Herrup K - Nat. Med. (2012)

Nuclear accumulation HDAC4 leads to global effects on histone acetylation and neuronal gene expressiona) Fluorescent images of Atm+/+ and Atm−/− cerebellum sections immunostained for different histones and acetylated histones as indicated.b) Protein extracts of cortex and cerebellum from wild-type and Atm−/− mice were probed with various histone antibodies as labeled to the left of the gels.c-d) Quantification of 3 repetitions of the experiment illustrated in panel I. Error bars denotes standard deviations. * = p<0.05 (by Student’s T-test).e-g) Fragmented chromatin was immunoprecipitated with the antibodies indicated and quantified with real-time PCR. The primers used for q-PCR are listed in Table S1. Statistical analysis was carried out using Student’s t test. Error bars represent SEMh) An illustration of the HDAC4 ChIP-seq alignment and peaks. A 2.7 Mb sample region of chromosome 1 shows the density of coverage of 35 nt sequencing tags from input DNA or ChIP from wild type (blue) or Atm−/− (red) mouse brain.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3378917&req=5

Figure 2: Nuclear accumulation HDAC4 leads to global effects on histone acetylation and neuronal gene expressiona) Fluorescent images of Atm+/+ and Atm−/− cerebellum sections immunostained for different histones and acetylated histones as indicated.b) Protein extracts of cortex and cerebellum from wild-type and Atm−/− mice were probed with various histone antibodies as labeled to the left of the gels.c-d) Quantification of 3 repetitions of the experiment illustrated in panel I. Error bars denotes standard deviations. * = p<0.05 (by Student’s T-test).e-g) Fragmented chromatin was immunoprecipitated with the antibodies indicated and quantified with real-time PCR. The primers used for q-PCR are listed in Table S1. Statistical analysis was carried out using Student’s t test. Error bars represent SEMh) An illustration of the HDAC4 ChIP-seq alignment and peaks. A 2.7 Mb sample region of chromosome 1 shows the density of coverage of 35 nt sequencing tags from input DNA or ChIP from wild type (blue) or Atm−/− (red) mouse brain.
Mentions: Enhanced HDAC4 in Atm−/− neuronal nuclei suggests a reduction of histone acetylation in these cells. Immunostaining for total histone 3 (H3) and 4 (H4) of Atm−/− cerebellum was similar to that of wild-type (Fig. 2a). By contrast, reduced immunostaining for acetylated histone 3 (AcH3) and 4 (AcH4) were found in Atm−/− neocortex and hippocampus (data not shown). These findings were confirmed by Western blots (Fig. 2b-d). We then examined the association of AcH3 and AcH4 with specific gene promoters. ChIP followed by qPCR assays was performed with extracts of wild-type and Atm−/− mouse cerebellum (Fig. 2e-g). H3 ChIP revealed no consistent difference between wild-type and Atm−/− samples in chromatin association at the promoters we examined (Fig. 2e). By contrast, the association of AcH3 and AcH4 with multiple neuronal growth genes was consistently decreased in Atm−/−. The loss of histone acetylation in a promoter region suggests a closed chromatin configuration and reduced transcription. As predicted, in Atm−/− samples, we observed decreased transcription of multiple neuronal genes at which promoter occupancy by acetylated histones was reduced, e.g., Bdnf, NR2a and Nrxn (Fig. 2f-g). Their occupancy by H3 (Fig. 2e) and H4 (not shown) were equivalent to wild-type.

Bottom Line: To remain cytoplasmic, HDAC4 must be phosphorylated.The activity of the HDAC4 phosphatase, protein phosphatase 2A (PP2A), is downregulated by ATM-mediated phosphorylation.In ATM deficiency, enhanced PP2A activity leads to HDAC4 dephosphorylation and the nuclear accumulation of HDAC4.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Neuroscience, Nelson Biological Laboratories, Rutgers University, Piscataway, New Jersey, USA.

ABSTRACT
Ataxia telangiectasia is a neurodegenerative disease caused by mutation of the Atm gene. Here we report that ataxia telangiectasia mutated (ATM) deficiency causes nuclear accumulation of histone deacetylase 4 (HDAC4) in neurons and promotes neurodegeneration. Nuclear HDAC4 binds to chromatin, as well as to myocyte enhancer factor 2A (MEF2A) and cAMP-responsive element binding protein (CREB), leading to histone deacetylation and altered neuronal gene expression. Blocking either HDAC4 activity or its nuclear accumulation blunts these neurodegenerative changes and rescues several behavioral abnormalities of ATM-deficient mice. Full rescue of the neurodegeneration, however, also requires the presence of HDAC4 in the cytoplasm, suggesting that the ataxia telangiectasia phenotype results both from a loss of cytoplasmic HDAC4 as well as its nuclear accumulation. To remain cytoplasmic, HDAC4 must be phosphorylated. The activity of the HDAC4 phosphatase, protein phosphatase 2A (PP2A), is downregulated by ATM-mediated phosphorylation. In ATM deficiency, enhanced PP2A activity leads to HDAC4 dephosphorylation and the nuclear accumulation of HDAC4. Our results define a crucial role of the cellular localization of HDAC4 in the events leading to ataxia telangiectasia neurodegeneration.

Show MeSH
Related in: MedlinePlus