TY - JOUR
T1 - Reduced C9orf72 gene expression in c9FTD/ALS is caused by histone trimethylation, an epigenetic event detectable in blood
AU - Belzil, Veronique V.
AU - Bauer, Peter O.
AU - Prudencio, Mercedes
AU - Gendron, Tania F.
AU - Stetler, Caroline T.
AU - Yan, Irene K.
AU - Pregent, Luc
AU - Daughrity, Lillian
AU - Baker, Matthew C.
AU - Rademakers, Rosa
AU - Boylan, Kevin
AU - Patel, Tushar C.
AU - Dickson, Dennis W.
AU - Petrucelli, Leonard
N1 - Funding Information:
Acknowledgments We would like to thank the patients involved in this study as well as acknowledge the technical support of Jeannette N. Stankowski, Yong-Jie Zhang, Karen r. Jansen-West, Jen-nifer M. gass, Kristin Staggs-Douberly, Pamela Desaro, Amelia Johnston, Marka M. Van Blitterswijk, Patricia H. Brown, Melissa e. Murray, Kevin F. Bieniek, Amanda M. liesinger, and linda g. rousseau from Mayo Clinic. This work was supported by Mayo Clinic Foundation, National Institutes of Health/National Institute on Aging [r01Ag026251 (lP)], National Institutes of Health/National Institute of Neurological Disorders and Stroke [r01 NS 063964-01 (lP), r01 NS077402 (lP)], National Institute of environmental Health Services [eS20395-01 (lP)], Amyotrophic lateral Sclerosis Association (lP), the Canadian Institutes of Health research (VVB), and the Siragusa Foundation (VVB).
PY - 2013/12
Y1 - 2013/12
N2 - Individuals carrying (GGGGCC) expanded repeats in the C9orf72 gene represent a significant portion of patients suffering from amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Elucidating how these expanded repeats cause "c9FTD/ALS" has since become an important goal of the field. Toward this end, we sought to investigate whether epigenetic changes are responsible for the decrease in C9orf72 expression levels observed in c9FTD/ALS patients. We obtained brain tissue from ten c9FTD/ALS individuals, nine FTD/ALS cases without a C9orf72 repeat expansion, and nine disease control participants, and generated fibroblastoid cell lines from seven C9orf72 expanded repeat carriers and seven participants carrying normal alleles. Chromatin immunoprecipitation using antibodies for histone H3 and H4 trimethylated at lysines 9 (H3K9), 27 (H3K27), 79 (H3K79), and 20 (H4K20) revealed that these trimethylated residues bind strongly to C9orf72 expanded repeats in brain tissue, but not to non-pathogenic repeats. Our finding that C9orf72 mRNA levels are reduced in the frontal cortices and cerebella of c9FTD/ALS patients is consistent with trimethylation of these histone residues, an event known to repress gene expression. Moreover, treating repeat carrier-derived fibroblasts with 5-aza-2-deoxycytidine, a DNA and histone demethylating agent, not only decreased C9orf72 binding to trimethylated histone residues, but also increased C9orf72 mRNA expression. Our results provide compelling evidence that trimethylation of lysine residues within histones H3 and H4 is a novel mechanism involved in reducing C9orf72 mRNA expression in expanded repeat carriers. Of importance, we show that mutant C9orf72 binding to trimethylated H3K9 and H3K27 is detectable in blood of c9FTD/ALS patients. Confirming these exciting results using blood from a larger cohort of patients may establish this novel epigenetic event as a biomarker for c9FTD/ALS.
AB - Individuals carrying (GGGGCC) expanded repeats in the C9orf72 gene represent a significant portion of patients suffering from amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Elucidating how these expanded repeats cause "c9FTD/ALS" has since become an important goal of the field. Toward this end, we sought to investigate whether epigenetic changes are responsible for the decrease in C9orf72 expression levels observed in c9FTD/ALS patients. We obtained brain tissue from ten c9FTD/ALS individuals, nine FTD/ALS cases without a C9orf72 repeat expansion, and nine disease control participants, and generated fibroblastoid cell lines from seven C9orf72 expanded repeat carriers and seven participants carrying normal alleles. Chromatin immunoprecipitation using antibodies for histone H3 and H4 trimethylated at lysines 9 (H3K9), 27 (H3K27), 79 (H3K79), and 20 (H4K20) revealed that these trimethylated residues bind strongly to C9orf72 expanded repeats in brain tissue, but not to non-pathogenic repeats. Our finding that C9orf72 mRNA levels are reduced in the frontal cortices and cerebella of c9FTD/ALS patients is consistent with trimethylation of these histone residues, an event known to repress gene expression. Moreover, treating repeat carrier-derived fibroblasts with 5-aza-2-deoxycytidine, a DNA and histone demethylating agent, not only decreased C9orf72 binding to trimethylated histone residues, but also increased C9orf72 mRNA expression. Our results provide compelling evidence that trimethylation of lysine residues within histones H3 and H4 is a novel mechanism involved in reducing C9orf72 mRNA expression in expanded repeat carriers. Of importance, we show that mutant C9orf72 binding to trimethylated H3K9 and H3K27 is detectable in blood of c9FTD/ALS patients. Confirming these exciting results using blood from a larger cohort of patients may establish this novel epigenetic event as a biomarker for c9FTD/ALS.
KW - Amyotrophic lateral sclerosis
KW - C9orf72
KW - Epigenetic modification
KW - Frontotemporal dementia
KW - Histone methylation
KW - Repeat expansion
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U2 - 10.1007/s00401-013-1199-1
DO - 10.1007/s00401-013-1199-1
M3 - Article
C2 - 24166615
AN - SCOPUS:84892596606
SN - 0001-6322
VL - 126
SP - 895
EP - 905
JO - Acta neuropathologica
JF - Acta neuropathologica
IS - 6
ER -