Heterochromatin Protein 1a Stimulates Histone H3 Lysine 36 Demethylation by the Drosophila KDM4A Demethylase

Abstract

Summary Recent discoveries of histone demethylases demonstrate that histone methylation is reversible. However, mechanisms governing the targeting and regulation of histone demethylation remain elusive. Here we report that a Drosophila melanogaster JmjC domain-containing protein, dKDM4A, is a histone H3K36 demethylase. dKDM4A specifically demethylates H3K36me2 and me3 both in vitro and in vivo. Affinity purification and mass spectrometry analysis revealed that Heterochromatin Protein 1a (HP1a) associates with dKDMA4A. We found that the chromoshadow domain of HP1a and a HP1-interacting motif of dKDM4A are responsible for this interaction. HP1a stimulates the histone H3K36 demethylation activity of dKDM4A and this stimulation depends on the H3K9me binding motif of HP1a. Finally, we provide in vivo evidence suggesting that HP1a and dKDM4A interact with each other and loss of HP1a leads to increased level of histone H3K36me3. Collectively, these results suggest a function of HP1a in transcription facilitating H3K36 demethylation at transcribed and/or heterochromatin regions.

Heterochromatin protein 1 (HP1) connects the FACT histone chaperone complex to the phosphorylated CTD of RNA polymerase II

“…In agreement with a euchromatin function, HP1a targets to highly expressed genes, including developmentally regulated genes and Hsp70, where it controls gene expression after heat shock (Biasin et al 2003). Moreover, recent studies have shown that HP1a is a positive regulator of transcription by facilitating H3K36 demethylation at active and/or heterochromatic regions (Lin et al 2008), and that it positively regulates euchromatic gene expression by interacting with RNA transcripts and hnRNPs (heterogeneous nuclear ribonucleoproteins) in Drosophila (Piacentini et al 2009). These data suggest that, in addition to its function in gene silencing, HP1 might also play an activating role in gene regulation.…”

Histone acetyltransferase Enok regulates oocyte polarization by promoting expression of the actin nucleation factor spire

“…dsRNAs targeting LacZ or enok were synthesized as described previously (Lin et al 2008). S2 cells were seeded at 1 3 10 6 cells per milliliter in serum-free Schneider's insect medium for RNAi treatment.…”

Heterochromatin-associated interactions of Drosophila HP1a with dADD1, HIPP1, and repetitive RNAs

“…HP1a interactors have been identified previously using yeast two-hybrid screens (Shaffer et al 2002;Giot et al 2003), and HP1a has been recovered from pull-downs of several chromatin-associated protein complexes (Badugu et al 2003;Lin et al 2008;Emelyanov et al 2010;Nozawa et al 2010). HP1a also has been analyzed by inducible expression, affinity purification, and mass spectrometry (Lin et al 2008;Ryu et al 2014).…”

“…HP1a also has been analyzed by inducible expression, affinity purification, and mass spectrometry (Lin et al 2008;Ryu et al 2014). However, a comprehensive picture based on HP1a expressed at endogenous levels within the organism has been lacking.…”