title: The MEK/ERK pathway promotes NOTCH signalling in pancreatic cancer cells.
abstract: Activation of the NOTCH receptors relies on their intracellular proteolysis by the gamma-secretase complex. This cleavage liberates the NOTCH intracellular domain (NIC) thereby allowing the translocation of NIC towards the nucleus to assemble into a transcriptional platform. Little information is available regarding the regulatory steps operating on NIC following its release from the transmembrane receptor up to its association with transcriptional partners. Interfering with these regulatory steps might potentially influences the nuclear outcome of NOTCH signalling. Herein, we exploited a reliable model to study the molecular events occurring subsequent to NOTCH1 cleavage. In pancreatic cancer cells, pulse of NOTCH1 activation led to increased expression of NOTCH target genes namely HES1 and c-MYC. We uncovered that, upon its release, the NOTCH1 intracellular domain, NIC1, undergoes a series of post-translational modifications that include phosphorylation. Most interestingly, we found that activation of the MEK/ERK pathway promotes HES1 expression. Inhibition of the gamma-secretase complex prevented the MEK/ERK-induced HES1 expression suggesting a NOTCH-dependent mechanism. Finally, higher levels of NIC1 were found associated with its transcriptional partners [CBF1, Su(H) and LAG-1] (CSL) and MASTERMIND-LIKE 1 (MAML1) upon MEK/ERK activation providing a potential mechanism whereby the MEK/ERK pathway promotes expression of NOTCH target genes. For the first time, our data exposed a signalling pathway, namely the MEK/ERK pathway that positively impacts on NOTCH nuclear outcome.
authors.affiliation: Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Tremblay
authors.affiliation: Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Paré
authors.affiliation: Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Dominique
authors.initials: D
authors.lastname: Arsenault
authors.affiliation: Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Douziech
authors.affiliation: Department of Medicine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Boucher
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000473:pathology*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D051881:Receptor, Notch1 / Q000737:chemistry / Q000378:metabolism*; D000072056:Transcription Factor HES-1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002118:Calcium; D048049:Extracellular Signal-Regulated MAP Kinases; D018398:Homeodomain Proteins; D020929:Mitogen-Activated Protein Kinase Kinases; D051881:Receptor, Notch1; D000072056:Transcription Factor HES-1; C078493:HES1 protein, human