Jmjd2b antagonizes H3K9 trimethylation at pericentric heterochromatin in mammalian cells

Abstract

Histone lysine trimethyl states represent some of the most robust epigenetic modifications in eukaryotic chromatin. Using a candidate approach, we identified the subgroup of murine Jmjd2 proteins to antagonize H3K9me3 at pericentric heterochromatin. H3K27me3 and H4K20me3 marks are not impaired in inducible Jmjd2b-GFP cell lines, but Jmjd2b also reduces H3K36 methylation. Since recombinant Jmjd2b appears as a very poor enzyme, we applied metabolic labeling with heavy methyl groups to demonstrate Jmjd2b-mediated removal of chromosomal H3K9me3 as an active process that occurs well before replication of chromatin. These data reveal that certain members of the jmjC class of hydroxylases can work in a pathway that actively antagonizes a histone lysine trimethyl state. Histone lysine methylation is a central epigenetic modification with both activating and repressive roles in eukaryotic chromatin (Kouzarides 2002;Fischle et al. 2003;Lachner et al. 2004;Reinberg et al. 2004). There are five lysine residues in the histone N termini that are prominently methylated, with H3K4 and H3K36 methylation primarily transducing activating functions, whereas H3K9, H3K27, and H4K20 methylation is mainly associated with repressed chromatin. Histone lysine methylation can be presented as mono-, di-, or trimethyl states, where each distinct methyl state confers different biological read-outs (Santos-Rosa et al. 2002;Lachner et al. 2004). Histone lysine trimethyl states, particularly for the repressive functions, appear relatively robust, since they are stably propagated during several cell divisions Reinberg et al. 2004;Schotta et al. 2004) and resist reprogramming in early mammalian embryos (Santos et al. 2003).Until recently, no enzymatic mechanism had been described that would directly remove histone lysine methylation, although amine oxidation or radical attack by hydroxylation could destabilize the amino-methyl bond Bannister and Kouzarides 2005;Trewick et al. 2005). Indeed, a lysine-specific demethylase 1 (LSD1) has been shown to demethylate H3K4me2 (an active mark) (Shi et al. 2004) and, when associated with a different protein complex, also appears to convert H3K9me2 (a repressive mark) (Metzger et al. 2005). Based on the reaction mechanism, LSD1 cannot act on a lysine trimethyl state, and more potent mechanisms, involving attack by oxygen radicals via hydroxylases/dioxygenases, have been postulated (Clissold and Ponting 2001;Trewick et al. 2005). This could be inferred from the activities of the Escherichia coli AlkB enzyme to counteract alkylating damage of DNA or from other protein hydroxylases, such as the jmjC (jumonji) domain containing protein Factor Inhibiting Hypoxia (FIH) (Lando et al. 2002). In Schizosaccharomyces pombe, there is one silencing modifier, Epe1, which also carries a jmjC domain, and this factor antagonizes repressive H3K9me2 at centromeric regions (Ayoub et al. 2003). In addition, there are several jmjC proteins that have been shown to be important transcriptional/chromatin regulators (Takeuchi et al. 19...

Histone demethylase JMJD2B coordinates H3K4/H3K9 methylation and promotes hormonally responsive breast carcinogenesis

“…As stated before, JMJD2B has been demonstrated to be able to demethylate H3K9me3 at pericentric heterochromatin in mammalian cells (20,21). In light of our observation that JMJD2B influences ERα-regulated transcription and its demethylase activity is essential for that effect, it is logical to postulate that JMJD2B may also function in euchromatin regions and act to erase the H3K9me3 mark in ERα-activated transcription.…”

“…To further support this observation and to investigate whether or not H3K4 methylation is affected by H3K9me3 demethylation, mouse Jmjd2b (W-mJmjd2b or M-mJmjd2b) (20,28) was transfected into JMJD2B-depleted (with stable transfection of JMJD2B-specific siRNA molecules) MCF-7 cells. These cells were deprived of estrogen for 3 d and then treated with E2.…”

“…Specifically, it has been reported that, in euchromatin, JHDM2A catalyzes the removal of mono-and dimethylation at H3K9 (H3K9me1/2) (18) and JMJD2C acts to erase trimethylation at H3K9 (H3K9me3) (19), whereas JMJD2B has been shown to demethylate H3K9me3 at pericentric heterochromatin in mammalian cells (20,21). A role for JMJD2B in euchromatin function has not yet been defined.…”

Epigenetic regulation of cancer growth by histone demethylases

“…Indeed, ectopic expression of JMJD2A, -B and -C significantly decreased H3K9me3/2 levels, and delocalized HP1. 14,38 Thus, cancer cells with high expression of JMJD2 might evade this important tumor suppressor mechanism. 14 In agreement with the oncogenic potential of JMJD2 to tumor development, overexpression of JMJD2 proteins was observed in prostate cancer.…”

Isolation and characterization of histone H3 lysine 4 demethylase-containing complexes

“…Though histone methylation was originally considered irreversible, recent studies have demonstrated that it can be reversed by several histone demethylases including PAD4/ PADI4, BHC110/LSD1 and a new family of JmjC domain-containing histone demethylases (Cloos et al, 2006;Cuthbert et al, 2004;Fodor et al, 2006;Klose et al, 2006;Shi et al, 2004;Tsukada et al, 2006;Wang et al, 2004;Whetstine et al, 2006;Yamane et al, 2006).…”