Hypoxic stress induces dimethylated histone H3 lysine 9 through histone methyltransferase G9a in mammalian cells.

Dimethylated histone H3 lysine 9 (H3K9me2) is a critical epigenetic mark for gene repression and silencing and plays an essential role in embryogenesis and carcinogenesis. Here, we investigated the effects of hypoxic stress on H3K9me2 at both global and gene-specific level. We found that hypoxia increased global H3K9me2 in several mammalian cell lines. This hypoxia-induced H3K9me2 was temporally correlated with an increase in histone methyltransferase G9a protein and enzyme activity. The increase in H3K9me2 was significantly mitigated in G9a-/- mouse embryonic stem cells following hypoxia challenge, indicating that G9a was involved in the hypoxia-induced H3K9me2. In addition to the activation of G9a, our results also indicated that hypoxia increased H3K9me2 by inhibiting H3K9 demethylation processes. Hypoxic mimetics, such as deferoxamine and dimethyloxalylglycine, were also found to increase H3K9me2 as well as G9a protein and activity. Finally, hypoxia increased H3K9me2 in the promoter regions of the Mlh1 and Dhfr genes, and these increases temporally correlated with the repression of these genes. Collectively, these results indicate that G9a plays an important role in the hypoxia-induced H3K9me2, which would inhibit the expression of several genes that would likely lead to solid tumor progression.

[1]  Todd L Davidson,et al.  Soluble nickel inhibits HIF‐prolyl‐hydroxylases creating persistent hypoxic signaling in A549 cells , 2006, Molecular carcinogenesis.

[2]  Paul Tempst,et al.  JHDM2A, a JmjC-Containing H3K9 Demethylase, Facilitates Transcription Activation by Androgen Receptor , 2006, Cell.

[3]  Yang Shi,et al.  Reversal of Histone Lysine Trimethylation by the JMJD2 Family of Histone Demethylases , 2006, Cell.

[4]  Yan Yan,et al.  Nickel Ions Increase Histone H3 Lysine 9 Dimethylation and Induce Transgene Silencing , 2006, Molecular and Cellular Biology.

[5]  Kelly M. McGarvey,et al.  Silenced tumor suppressor genes reactivated by DNA demethylation do not return to a fully euchromatic chromatin state. , 2006, Cancer research.

[6]  H. Erdjument-Bromage,et al.  Histone demethylation by a family of JmjC domain-containing proteins , 2006, Nature.

[7]  D. Brizel,et al.  Prognostic value of tumor oxygenation in 397 head and neck tumors after primary radiation therapy. An international multi-center study. , 2005, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[8]  Antoine H. F. M. Peters,et al.  LSD1 demethylates repressive histone marks to promote androgen-receptor-dependent transcription , 2005, Nature.

[9]  B. J. Roberts,et al.  Role of the von Hippel-Lindau tumour suppressor protein in the regulation of HIF-1α and its oxygen-regulated transactivation domains at high cell density , 2005, Oncogene.

[10]  Martha R. Stampfer,et al.  Chromatin Inactivation Precedes De Novo DNA Methylation during the Progressive Epigenetic Silencing of the RASSF1A Promoter , 2005, Molecular and Cellular Biology.

[11]  R. Allshire,et al.  Methylation: lost in hydroxylation? , 2005, EMBO reports.

[12]  A. Giaccia,et al.  Adaptive Myogenesis under Hypoxia , 2005, Molecular and Cellular Biology.

[13]  Tsutomu Ohta,et al.  Histone methyltransferases G9a and GLP form heteromeric complexes and are both crucial for methylation of euchromatin at H3-K9. , 2005, Genes & development.

[14]  Yang Shi,et al.  Histone Demethylation Mediated by the Nuclear Amine Oxidase Homolog LSD1 , 2004, Cell.

[15]  M. Walsh,et al.  CCAAT displacement protein/cut homolog recruits G9a histone lysine methyltransferase to repress transcription. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[16]  C. Peterson,et al.  Histones and histone modifications , 2004, Current Biology.

[17]  A. Roopra,et al.  Localized domains of G9a-mediated histone methylation are required for silencing of neuronal genes. , 2004, Molecular cell.

[18]  Lianna Johnson,et al.  Dimethylation of histone H3 lysine 9 is a critical mark for DNA methylation and gene silencing in Arabidopsis thaliana , 2004, Chromosoma.

[19]  G. Semenza.  O2-regulated gene expression: transcriptional control of cardiorespiratory physiology by HIF-1. , 2004, Journal of applied physiology.

[20]  K. Wright,et al.  PRDI-BF1 recruits the histone H3 methyltransferase G9a in transcriptional silencing , 2004, Nature Immunology.

[21]  G. Felsenfeld,et al.  Silencing of transgene transcription precedes methylation of promoter DNA and histone H3 lysine 9 , 2004, The EMBO journal.

[22]  Beatrix Ueberheide,et al.  Histone methyltransferases direct different degrees of methylation to define distinct chromatin domains. , 2003, Molecular cell.

[23]  Yi Zhang,et al.  mAM facilitates conversion by ESET of dimethyl to trimethyl lysine 9 of histone H3 to cause transcriptional repression. , 2003, Molecular cell.

[24]  Yan Yan,et al.  Analysis of specific lysine histone H3 and H4 acetylation and methylation status in clones of cells with a gene silenced by nickel exposure. , 2003, Toxicology and applied pharmacology.

[25]  P. Glazer,et al.  Decreased Expression of the DNA Mismatch Repair Gene Mlh1 under Hypoxic Stress in Mammalian Cells , 2003, Molecular and Cellular Biology.

[26]  Manfred Kunz,et al.  Molecular responses to hypoxia in tumor cells , 2003, Molecular Cancer.

[27]  E. Nicolas,et al.  Balance between Acetylation and Methylation of Histone H3 Lysine 9 on the E2F-Responsive Dihydrofolate Reductase Promoter , 2003, Molecular and Cellular Biology.

[28]  H. Kato,et al.  G9a histone methyltransferase plays a dominant role in euchromatic histone H3 lysine 9 methylation and is essential for early embryogenesis. , 2002, Genes & development.

[29]  James B. Mitchell,et al.  Tumor hypoxia: chicken, egg, or a piece of the farm? , 2002, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[30]  D. Hedley,et al.  Tumor hypoxia has independent predictor impact only in patients with node-negative cervix cancer. , 2002, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[31]  R. Campbell,et al.  Novel NG36/G9a gene products encoded within the human and mouse MHC class III regions , 2001, Mammalian Genome.

[32]  D. Theodorescu,et al.  Cell density mediated pericellular hypoxia leads to induction of HIF-1α via nitric oxide and Ras/MAP kinase mediated signaling pathways , 2001, Oncogene.

[33]  C. Allis,et al.  Translating the Histone Code , 2001, Science.

[34]  T. L. Witt,et al.  Relationship of p15 and p16 gene alterations to elevated dihydrofolate reductase in childhood acute lymphoblastic leukaemia , 2001, British journal of haematology.

[35]  K. W. Kim,et al.  Human rad21 gene, hHR21(SP), is downregulated by hypoxia in human tumor cells. , 2001, Biochemical and biophysical research communications.

[36]  J. M. Arbeit,et al.  Hypoxia-inducible Factor-1α Is a Positive Factor in Solid Tumor Growth , 2000 .

[37]  J. Pouysségur,et al.  Identification of Alternative Spliced Variants of Human Hypoxia-inducible Factor-1α* , 2000, The Journal of Biological Chemistry.

[38]  A. Giaccia,et al.  Hypoxia induces p53 accumulation through MDM2 down-regulation and inhibition of E6-mediated degradation. , 1999, Cancer research.

[39]  L. Kasturi,et al.  Biallelic inactivation of hMLH1 by epigenetic gene silencing, a novel mechanism causing human MSI cancers. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[40]  J. Marshall,et al.  Hypoxia facilitates tumour cell detachment by reducing expression of surface adhesion molecules and adhesion to extracellular matrices without loss of cell viability. , 1998, British Journal of Cancer.

[41]  W. Birchmeier,et al.  Cadherin expression in carcinomas: role in the formation of cell junctions and the prevention of invasiveness. , 1994, Biochimica et biophysica acta.

[42]  H. W. Lee,et al.  Studies on compartmentation of S-adenosyl-L-methionine in Saccharomyces cerevisiae and isolated rat hepatocytes. , 1983, Biochimica et biophysica acta.

[43]  J. Folkman.  Tumor angiogenesis: therapeutic implications. , 1971, The New England journal of medicine.

[44]  Lin Guo-yuan.  Molecular responses to hypoxia in tumor cells , 2006 .

[45]  I. Talianidis,et al.  Functional role of G9a-induced histone methylation in small heterodimer partner-mediated transcriptional repression. , 2004, Nucleic acids research.

[46]  M. Blagosklonny,et al.  Carcinogenic nickel induces genes involved with hypoxic stress. , 2000, Cancer research.