RT Journal Article
SR Electronic
T1 Vitamin K3 (Menadione)-Induced Oncosis Associated with Keratin 8 Phosphorylation and Histone H3 Arylation
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 606
OP 615
DO 10.1124/mol.105.013474
VO 68
IS 3
A1 Gary K. Scott
A1 Christian Atsriku
A1 Patrick Kaminker
A1 Jason Held
A1 Brad Gibson
A1 Michael A. Baldwin
A1 Christopher C. Benz
YR 2005
UL http://molpharm.aspetjournals.org/content/68/3/606.abstract
AB The vitamin K analog menadione (K3), capable of both redox cycling and arylating nucleophilic substrates by Michael addition, has been extensively studied as a model stress-inducing quinone in both cell culture and animal model systems. Exposure of keratin 8 (k-8) expressing human breast cancer cells (MCF7, T47D, SKBr3) to K3 (50-100 μM) induced rapid, sustained, and site-specific k-8 serine phosphorylation (pSer73) dependent on signaling by a single mitogen activated protein kinase (MAPK) pathway, MEK1/2. Normal nuclear morphology and k-8 immunofluorescence coupled with the lack of DNA laddering or other features of apoptosis indicated that K3-induced cytotoxicity, evident within 4 h of treatment and delayed but not prevented by MEK1/2 inhibition, was due to a form of stress-activated cell death known as oncosis. Independent of MAPK signaling was the progressive appearance of K3-induced cellular fluorescence, principally nuclear in origin and suggested by in vitro fluorimetry to have been caused by K3 thiol arylation. Imaging by UV transillumination of protein gels containing nuclear extracts from K3-treated cells revealed a prominent 17-kDa band shown to be histone H3 by immunoblotting and mass spectrometry (MS). K3 arylation of histones in vitro followed by electrospray ionization-tandem MS analyses identified the unique Cys110 residue within H3, exposed only in the open chromatin of transcriptionally active genes, as a K3 arylation target. These findings delineate new pathways associated with K3-induced stress and suggest a potentially novel role for H3 Cys110 as a nuclear stress sensor.