title: EZH1 and EZH2 cogovern histone H3K27 trimethylation and are essential for hair follicle homeostasis and wound repair.
abstract: Polycomb protein group (PcG)-dependent trimethylation on H3K27 (H3K27me3) regulates identity of embryonic stem cells (ESCs). How H3K27me3 governs adult SCs and tissue development is unclear. Here, we conditionally target H3K27 methyltransferases Ezh2 and Ezh1 to address their roles in mouse skin homeostasis. Postnatal phenotypes appear only in doubly targeted skin, where H3K27me3 is abolished, revealing functional redundancy in EZH1/2 proteins. Surprisingly, while Ezh1/2-null hair follicles (HFs) arrest morphogenesis and degenerate due to defective proliferation and increased apoptosis, epidermis hyperproliferates and survives engraftment. mRNA microarray studies reveal that, despite these striking phenotypic differences, similar genes are up-regulated in HF and epidermal Ezh1/2-null progenitors. Featured prominently are (1) PcG-controlled nonskin lineage genes, whose expression is still significantly lower than in native tissues, and (2) the PcG-regulated Ink4a/Inkb/Arf locus. Interestingly, when EZH1/2 are absent, even though Ink4a/Arf/Ink4b genes are fully activated in HF cells, they are only partially so in epidermal progenitors. Importantly, transduction of Ink4b/Ink4a/Arf shRNAs restores proliferation/survival of Ezh1/2-null HF progenitors in vitro, pointing toward the relevance of this locus to the observed HF phenotypes. Our findings reveal new insights into Polycomb-dependent tissue control, and provide a new twist to how different progenitors within one tissue respond to loss of H3K27me3.
authors.affiliation: Howard Hughes Medical Institute, Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, New York 10065, USA;
authors.forename: Elena
authors.initials: E
authors.lastname: Ezhkova
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Lien
authors.forename: Nicole
authors.initials: N
authors.lastname: Stokes
authors.forename: H Amalia
authors.initials: HA
authors.lastname: Pasolli
authors.forename: Jose M
authors.initials: JM
authors.lastname: Silva
authors.forename: Elaine
authors.initials: E
authors.lastname: Fuchs
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics; D017209:Apoptosis / Q000235:genetics; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000235:genetics; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000071221:Enhancer of Zeste Homolog 2 Protein; D000078404:Epidermal Cells; D004817:Epidermis / Q000637:transplantation; D005786:Gene Expression Regulation; D055786:Gene Knockout Techniques; D018859:Hair Follicle / Q000166:cytology / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis / Q000235:genetics*; D056484:Jumonji Domain-Containing Histone Demethylases / Q000378:metabolism*; D008745:Methylation; D063151:Polycomb Repressive Complex 2; D016038:Skin Transplantation; D013234:Stem Cells / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014945:Wound Healing / Q000235:genetics*
chemical_list: D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D056484:Jumonji Domain-Containing Histone Demethylases; C523761:Kdm6b protein, mouse; D000071221:Enhancer of Zeste Homolog 2 Protein; C498408:Ezh1 protein, mouse; C498410:Ezh2 protein, mouse; D011495:Histone-Lysine N-Methyltransferase; D063151:Polycomb Repressive Complex 2; D020823:ADP-Ribosylation Factor 1