ETS Proto-oncogene 1 Transcriptionally Up-regulates the Cholangiocyte Senescence-associated Protein Cyclin-dependent Kinase Inhibitor 2A.
Primary sclerosing cholangitis (PSC) is a chronic, fibroinflammatory cholangiopathy (disease of the bile ducts) of unknown pathogenesis. We reported that cholangiocyte senescence features prominently in PSC and that neuroblastoma RAS viral oncogene homolog (NRAS) is activated in PSC cholangiocytes. Additionally, persistent microbial insult (e.g.LPSs) induces cyclin-dependent kinase inhibitor 2A (CDKN2A/p16INK4a) expression and senescence in cultured cholangiocytes in an NRAS-dependent manner. However, the molecular mechanisms involved in LPS-induced cholangiocyte senescence and NRAS-dependent regulation of CDKN2A remain unclear. Using ourin vitrosenescence model, we found that LPS-inducedCDKN2Aexpression coincided with a 4.5-fold increase inETS1(ETS proto-oncogene 1) mRNA, suggesting that ETS1 is involved in regulatingCDKN2AThis idea was confirmed by RNAi-mediated suppression or genetic deletion of ETS1, which blocked CDKN2A expression and reduced cholangiocyte senescence. Furthermore, site-directed mutagenesis of a predicted ETS-binding site within theCDKN2Apromoter abolished luciferase reporter activity. Pharmacological inhibition of RAS/MAPK reduced ETS1 and CDKN2A protein expression andCDKN2Apromoter-driven luciferase activity by ∼50%. In contrast, constitutively active NRAS expression induced ETS1 and CDKN2A protein expression, whereas ETS1 RNAi blocked this increase. Chromatin immunoprecipitation-PCR detected increased ETS1 and histone 3 lysine 4 trimethylation (H3K4Me3) at theCDKN2Apromoter following LPS-induced senescence. Additionally, phospho-ETS1 expression was increased in cholangiocytes of human PSC livers and in theAbcb4(Mdr2)-/-mouse model of PSC. These data pinpoint ETS1 and H3K4Me3 as key transcriptional regulators in NRAS-induced expression ofCDKN2A, and this regulatory axis may therefore represent a potential therapeutic target for PSC treatment.
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Steven P
SP
O'Hara
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Patrick L
PL
Splinter
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Christy E
CE
Trussoni
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Maria J Lorenzo
MJ
Pisarello
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Lorena
L
Loarca
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Noah S
NS
Splinter
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905.
Bryce F
BF
Schutte
From the Division of Gastroenterology and Hepatology, and the Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, Minnesota 55905 larusso.nicholas@mayo.edu.
Nicholas F
NF
LaRusso
D000818:Animals; D002460:Cell Line; D016922:Cellular Senescence; D015209:Cholangitis, Sclerosing / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics* / Q000276:immunology; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology; D008099:Liver / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D051379:Mice; D000090063:Proto-Oncogene Mas; D050784:Proto-Oncogene Protein c-ets-1 / Q000235:genetics* / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D015533:Transcriptional Activation; D015854:Up-Regulation
D019941:Cyclin-Dependent Kinase Inhibitor p16; C494041:ETS1 protein, human; D008070:Lipopolysaccharides; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D050784:Proto-Oncogene Protein c-ets-1; D012333:RNA, Messenger
CDKN2A; Cholangiocytes; ETS1; cell signaling; epigenetics; epithelial cell; senescence; transcription