title: BRCA1 interacts with and is required for paclitaxel-induced activation of mitogen-activated protein kinase kinase kinase 3.
abstract: BRCA1 has been implicated in a number of cellular processes, including transcriptional regulation, DNA damage repair, cell cycle arrest, and apoptosis. We identified mitogen-activated protein kinase (MAPK) kinase kinase 3 (MEKK3), an upstream regulator of the c-Jun NH(2)-terminal kinase/stress-activated protein kinase and p38/MAPK pathways, as a novel BRCA1-interacting protein in a yeast two-hybrid screen and confirmed the interaction by coimmunoprecipitation in mammalian cells. Deletion mapping demonstrated that amino acids 1611-1863 are required to mediate the interaction with MEKK3 in yeast. BRCA1 disease-associated mutations abrogated the interaction in yeast, and BRCA1 failed to interact with MEKK3 in BRCA1 mutant HCC1937 breast cancer cells. We demonstrate that small interfering RNA-based inhibition of endogenous BRCA1 reduces MEKK3 kinase activity and conversely that inducible expression of BRCA1 activates MEKK3 and p38/MAPK. Finally, we demonstrate using complementary approaches that BRCA1 is required for paclitaxel-induced activation of MEKK3. These data indicate that BRCA1 is a key regulator of the paclitaxel-induced stress response pathway and suggest that the ability of BRCA1 to associate with, and mediate the activation of, MEKK3 represents a potential mechanism through which this pathway is regulated.
authors.affiliation: Department of Oncology, Cancer Research Centre, Queens University Belfast, Belfast, Northern Ireland.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Gilmore
authors.forename: Nuala
authors.initials: N
authors.lastname: McCabe
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Quinn
authors.forename: Richard D
authors.initials: RD
authors.lastname: Kennedy
authors.forename: Julia J
authors.initials: JJ
authors.lastname: Gorski
authors.forename: Heather N
authors.initials: HN
authors.lastname: Andrews
authors.forename: Stewart
authors.initials: S
authors.lastname: McWilliams
authors.forename: Michael
authors.initials: M
authors.lastname: Carty
authors.forename: Paul B
authors.initials: PB
authors.lastname: Mullan
authors.forename: W Paul
authors.initials: WP
authors.lastname: Duprex
authors.forename: Edison T
authors.initials: ET
authors.lastname: Liu
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Johnston
authors.forename: D Paul
authors.initials: DP
authors.lastname: Harkin
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D019313:BRCA1 Protein / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D001943:Breast Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D048748:MAP Kinase Kinase Kinase 3; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology*; D010957:Plasmids / Q000235:genetics; D017434:Protein Structure, Tertiary
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D019313:BRCA1 Protein; D048748:MAP Kinase Kinase Kinase 3; D020930:MAP Kinase Kinase Kinases; C482625:MAP3K3 protein, human; D017239:Paclitaxel