title: HER4 D-box sequences regulate mitotic progression and degradation of the nuclear HER4 cleavage product s80HER4.
abstract: Heregulin-mediated activation of HER4 initiates receptor cleavage (releasing an 80-kDa HER4 intracellular domain, s80(HER4), containing nuclear localization sequences) and results in G(2)-M delay by unknown signaling mechanisms. We report herein that s80(HER4) contains a functional cyclin B-like sequence known as a D-box, which targets proteins for degradation by anaphase-promoting complex (APC)/cyclosome, a multisubunit ubiquitin ligase. s80(HER4) ubiquitination and proteasomal degradation occurred during mitosis but not during S phase. Inhibition of an APC subunit (APC2) using short interfering RNA knockdown impaired s80(HER4) degradation. Mutation of the s80(HER4) D-box sequence stabilized s80(HER4) during mitosis, and s80(HER4)-dependent growth inhibition via G(2)-M delay was significantly greater with the D-box mutant. Polyomavirus middle T antigen-transformed HC11 cells expressing s80(HER4) resulted in smaller, less proliferative, more differentiated tumors in vivo than those expressing kinase-dead s80(HER4) or the empty vector. Cells expressing s80(HER4) with a disrupted D-box did not form tumors, instead forming differentiated ductal structures. These results suggest that cell cycle-dependent degradation of s80(HER4) limits its growth-inhibitory action, and stabilization of s80(HER4) enhances tumor suppression, thus providing a link between HER4-mediated growth inhibition and cell cycle control.
authors.affiliation: UNC Lineberger Comprehensive Cancer Center and Department of Medicine, University of North Carolina School of Medicine, 102 Mason Farm Road, Chapel Hill, NC 27599, USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Strunk
authors.forename: Carty
authors.initials: C
authors.lastname: Husted
authors.forename: Leah C
authors.initials: LC
authors.lastname: Miraglia
authors.forename: Melissa
authors.initials: M
authors.lastname: Sandahl
authors.forename: William A
authors.initials: WA
authors.lastname: Rearick
authors.forename: Debra M
authors.initials: DM
authors.lastname: Hunter
authors.forename: H Shelton
authors.initials: HS
authors.lastname: Earp
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Muraoka-Cook
mesh_terms: D020816:Amino Acid Motifs; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D002455:Cell Division; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D066246:ErbB Receptors / Q000502:physiology*; D016195:G2 Phase; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis; D020890:Neuregulin-1 / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D066247:Receptor, ErbB-4; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D000952:Antigens, Polyomavirus Transforming; D020890:Neuregulin-1; D025801:Ubiquitin; D049452:Green Fluorescent Proteins; C587689:ERBB4 protein, human; D066246:ErbB Receptors; D066247:Receptor, ErbB-4