The TrxG Complex Mediates Cytokine Induced De Novo Enhancer Formation in Islets.
To better understand how β-cells respond to proinflammatory cytokines we mapped the locations of histone 3 lysine 4 monomethylation (H3K4me1), a post-translational histone modification enriched at active and poised cis-regulatory regions, in IFNγ, Il-1β, and TNFα treated pancreatic islets. We identified 96,721 putative cis-regulatory loci, of which 3,590 were generated de novo, 3,204 had increased H3K4me1, and 5,354 had decreased H3K4me1 in IFNγ, Il-1β, and TNFα exposed islets. Roughly 10% of the de novo and increased regions were enriched for the repressive histone modification histone 3 lysine 27 trimethylation (H3K27me3) in untreated cells, and these were frequently associated with chemokine genes. We show that IFNγ, Il-1β, and TNFα exposure overcomes this repression and induces chemokine gene activation in as little as three hours, and that this expression persists for days in absence of continued IFNγ, Il-1β, and TNFα exposure. We implicate trithorax group (TrxG) complexes as likely players in the conversion of these repressed loci to an active state. To block the activity of these complexes, we suppressed Wdr5, a core component of the TrxG complexes, and used the H3K27me3 demethylase inhibitor GSK-J4. We show that GSK-J4 is particularly effective in blunting IFNγ, Il-1β, and TNFα-induced chemokine gene expression in β-cells; however, it induced significant islet-cell apoptosis and β-cell dysfunction. Wdr5 suppression also reduced IFNγ, Il-1β, and TNFα induced chemokine gene expression in β-cells without affecting islet-cell survival or β-cell function after 48hrs, but did begin to increase islet-cell apoptosis and β-cell dysfunction after four days of treatment. Taken together these data suggest that the TrxG complex is potentially a viable target for preventing cytokine induced chemokine gene expression in β-cells.
Child and Family Research Institute, British Columbia Children's Hospital and Sunny Hill Health Centre, 950 W28th Avenue, Vancouver, British Columbia, Canada.
Bryan R
BR
Tennant
Child and Family Research Institute, British Columbia Children's Hospital and Sunny Hill Health Centre, 950 W28th Avenue, Vancouver, British Columbia, Canada.
Peter
P
Hurley
Child and Family Research Institute, British Columbia Children's Hospital and Sunny Hill Health Centre, 950 W28th Avenue, Vancouver, British Columbia, Canada.
Jasmine
J
Dhillon
Child and Family Research Institute, British Columbia Children's Hospital and Sunny Hill Health Centre, 950 W28th Avenue, Vancouver, British Columbia, Canada.
Amol
A
Gill
Child and Family Research Institute, British Columbia Children's Hospital and Sunny Hill Health Centre, 950 W28th Avenue, Vancouver, British Columbia, Canada.
Cheryl
C
Whiting
Child and Family Research Institute, British Columbia Children's Hospital and Sunny Hill Health Centre, 950 W28th Avenue, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, B.C., Canada.
Brad G
BG
Hoffman
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001552:Benzazepines / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D011495:Histone-Lysine N-Methyltransferase / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D007371:Interferon-gamma / Q000008:administration & dosage; D053583:Interleukin-1beta / Q000008:administration & dosage; D047908:Intracellular Signaling Peptides and Proteins; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics; D051788:Myeloid-Lymphoid Leukemia Protein / Q000737:chemistry / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage
D001552:Benzazepines; C000593030:GSK-J4; D006657:Histones; D053583:Interleukin-1beta; D047908:Intracellular Signaling Peptides and Proteins; C497422:KMT2A protein, human; D046912:Multiprotein Complexes; D011506:Proteins; D011743:Pyrimidines; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha; C443118:Wdr5 protein, mouse; D051788:Myeloid-Lymphoid Leukemia Protein; D007371:Interferon-gamma; D011495:Histone-Lysine N-Methyltransferase