Chfr regulates a mitotic stress pathway through its RING-finger domain with ubiquitin ligase activity.
Resistance to chemotherapy targeting microtubules could be partially because of the delay in chromosome condensation and segregation during mitosis. The Chfr pathway has been defined recently, and its activation causes a delay in chromosome condensation in response to mitotic stress. Because Chfr contains a RING-finger domain, we tested whether Chfr inhibits chromosome condensation through an ubiquitin (ubiquitin)-dependent pathway. In the presence of purified E1, Ubc4, or Ubc5, and ubiquitin, Chfr catalyzes its own ubiquitination in vitro, an activity requiring the RING domain. In vivo, overexpressed Chfr but not a RING domain mutant is spontaneously ubiquitinated. Our studies with DLD1 cells stably expressing wild-type Chfr and Chfr lacking the RING domain indicated that the RING-finger deletion mutant was defective in inhibiting chromosome condensation after Taxol treatment. In addition, Chfr expression increases the survival rate after Taxol treatment, an activity requiring the RING domain. Preliminary studies indicate that Chfr expression is cell cycle regulated and is dependent on its ubiquitin ligase activity. It is very likely that the Chfr-mediated ubiquitin-dependent pathway is a critical component of the response to mitotic stress.
Chaturvedi
Priya
P
Department of Oncology Research, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406, USA.
Sudakin
Valery
V
Bobiak
Matthew L
ML
Fisher
Paul W
PW
Mattern
Michael R
MR
Jablonski
Sandra A
SA
Hurle
Mark R
MR
Zhu
Yuan
Y
Yen
Tim J
TJ
Zhou
Bin-Bing S
BB
D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D008938:Mitosis / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D017239:Paclitaxel / Q000494:pharmacology; D000075223:Poly-ADP-Ribose Binding Proteins; D017434:Protein Structure, Tertiary; D013312:Stress, Physiological; D019772:Topotecan / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D009363:Neoplasm Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D025801:Ubiquitin; D019772:Topotecan; C412002:CHFR protein, human; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D017239:Paclitaxel