Different EZH2-containing complexes target methylation of histone H1 or nucleosomal histone H3.

Human Enhancer of Zeste homolog (Ezh2) is a histone lysine methyltransferase (HKMT) associated with transcriptional repression. Ezh2 is present in several distinct complexes, one of which, PRC2, we characterized previously. Here we report an additional Ezh2 complex, PRC3. We show that the Ezh2 complexes exhibit differential targeting of specific histones for lysine methylation dependent upon the context of the histone substrates. This differential targeting is a function of the associated Eed protein within each complex. We found that Eed protein is present in four isoforms, which represent alternate translation start site usage from the same mRNA. These Eed isoforms selectively associate with distinct Ezh2-containing complexes with resultant differential targeting of their associated HKMT activity toward histone H3-K27 or histone H1-K26. Our data provide evidence for a novel mechanism regulating the substrate specificity of a chromatin-modifying enzyme through disparate translational products of a regulatory subunit.

[1]  Hengbin Wang,et al.  Role of Histone H3 Lysine 27 Methylation in X Inactivation , 2003, Science.

[2]  C. Ponting,et al.  Regulation of chromatin structure by site-specific histone H3 methyltransferases , 2000, Nature.

[3]  A. Wolffe,et al.  Review: chromatin structural features and targets that regulate transcription. , 2000, Journal of structural biology.

[4]  Brigitte Wild,et al.  Histone Methyltransferase Activity of a Drosophila Polycomb Group Repressor Complex , 2002, Cell.

[5]  Kevin Struhl,et al.  Lysine methylation within the globular domain of histone H3 by Dot1 is important for telomeric silencing and Sir protein association. , 2002, Genes & development.

[6]  V. Ramakrishnan,et al.  Position and orientation of the globular domain of linker histone H5 on the nucleosome , 1998, Nature.

[7]  D. Reinberg,et al.  ING 1 Candidate Tumor Suppressor p 33 Complex in Growth Regulation by the Role of the Sin 3-Histone Deacetylase , 2001 .

[8]  R. van Driel,et al.  Characterization of Interactions between the Mammalian Polycomb-Group Proteins Enx1/EZH2 and EED Suggests the Existence of Different Mammalian Polycomb-Group Protein Complexes , 1998, Molecular and Cellular Biology.

[9]  Wolfgang Fischle,et al.  Binary switches and modification cassettes in histone biology and beyond , 2003, Nature.

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

[11]  T. Richmond,et al.  Preparation of nucleosome core particle from recombinant histones. , 1999, Methods in enzymology.

[12]  K. Bomsztyk,et al.  The product of the murine homolog of the Drosophila extra sex combs gene displays transcriptional repressor activity , 1997, Molecular and cellular biology.

[13]  D. Reinberg,et al.  Transcription regulation by histone methylation: interplay between different covalent modifications of the core histone tails. , 2001, Genes & development.

[14]  T. Archer,et al.  Histone H1 Phosphorylation by Cdk2 Selectively Modulates Mouse Mammary Tumor Virus Transcription through Chromatin Remodeling , 2001, Molecular and Cellular Biology.

[15]  J. Min,et al.  Structural basis for specific binding of Polycomb chromodomain to histone H3 methylated at Lys 27. , 2003, Genes & development.

[16]  B. Daneholt,et al.  The ultrastructure of upstream and downstream regions of an active Balbiani ring gene , 1989, Cell.

[17]  N. Brockdorff,et al.  Mitotically Stable Association of Polycomb Group Proteins Eed and Enx1 with the Inactive X Chromosome in Trophoblast Stem Cells , 2002, Current Biology.

[18]  B. Holzmann,et al.  The Human WD Repeat Protein WAIT-1 Specifically Interacts with the Cytoplasmic Tails of β7-Integrins* , 1998, The Journal of Biological Chemistry.

[19]  Hengbin Wang,et al.  Role of Histone H3 Lysine 27 Methylation in Polycomb-Group Silencing , 2002, Science.

[20]  A. Wolffe,et al.  Asymmetric linker histone association directs the asymmetric rearrangement of core histone interactions in a positioned nucleosome containing a thyroid hormone response element. , 1998, Biochemistry.

[21]  S. Khochbin,et al.  Histone H1 diversity: bridging regulatory signals to linker histone function. , 2001, Gene.

[22]  D. Reinberg,et al.  Set9, a novel histone H3 methyltransferase that facilitates transcription by precluding histone tail modifications required for heterochromatin formation. , 2002, Genes & development.

[23]  T. Jenuwein,et al.  The many faces of histone lysine methylation. , 2002, Current opinion in cell biology.

[24]  D. Reinberg,et al.  Histone methyltransferase activity associated with a human multiprotein complex containing the Enhancer of Zeste protein. , 2002, Genes & development.

[25]  V. Pirrotta,et al.  Drosophila Enhancer of Zeste/ESC Complexes Have a Histone H3 Methyltransferase Activity that Marks Chromosomal Polycomb Sites , 2002, Cell.

[26]  N. Brockdorff,et al.  Establishment of histone h3 methylation on the inactive X chromosome requires transient recruitment of Eed-Enx1 polycomb group complexes. , 2003, Developmental cell.

[27]  J. Simon,et al.  A Drosophila ESC-E(Z) Protein Complex Is Distinct from Other Polycomb Group Complexes and Contains Covalently Modified ESC , 2000, Molecular and Cellular Biology.

[28]  E. Bradbury,et al.  Reversible histone modification and the chromosome cell cycle , 1992 .

[29]  Kevin Struhl,et al.  Methylation of H3-Lysine 79 Is Mediated by a New Family of HMTases without a SET Domain , 2002, Current Biology.

[30]  V. Orlando.  Polycomb, Epigenomes, and Control of Cell Identity , 2003, Cell.

[31]  Paul Tempst,et al.  PR-Set7 is a nucleosome-specific methyltransferase that modifies lysine 20 of histone H4 and is associated with silent chromatin. , 2002, Molecular cell.

[32]  Youngchang Kim,et al.  Molecular basis for the discrimination of repressive methyl-lysine marks in histone H3 by Polycomb and HP1 chromodomains. , 2003, Genes & development.

[33]  C. Allis,et al.  Methylation of Histone H3 at Lys-9 Is an Early Mark on the X Chromosome during X Inactivation , 2001, Cell.

[34]  T. Richmond,et al.  Crystal structure of the nucleosome core particle at 2.8 Å resolution , 1997, Nature.

[35]  T. Archer,et al.  Prolonged glucocorticoid exposure dephosphorylates histone H1 and inactivates the MMTV promoter , 1998, The EMBO journal.

[36]  V. Pirrotta,et al.  Related chromosome binding sites for zeste, suppressors of zeste and Polycomb group proteins in Drosophila and their dependence on Enhancer of zeste function. , 1993, The EMBO journal.

[37]  Philip R. Gafken,et al.  Dot1p Modulates Silencing in Yeast by Methylation of the Nucleosome Core , 2002, Cell.