RNA polymerase II large subunit is cleaved by caspases during DNA damage-induced apoptosis.
UV radiation induces DNA lesions that are repaired by the nucleotide excision repair (NER) pathway. Cells that are NER deficient such as those derived from xeroderma pigmentosum (XP) patients are susceptible to apoptosis after 10J/m(2) UV radiation, a dose largely survivable by repair proficient cells. Herein, we report that RNA polymerase II large subunit (RNAP II-LS) undergoes caspase-mediated cleavage, yielding a 140kDa C-terminal fragment in XP lymphoblasts but not NER proficient lymphoblasts after 10J/m(2) UV irradiation. Cleavage could also be induced by cisplatin or oxaliplatin, but not transplatin, an isomer of cisplatin that does not induce DNA adducts. The cleavage of RNAP II-LS was blocked by a panel of caspase inhibitors but not by proteasomal inhibitors or inhibitors of other proteases. In vitro cleavage with caspase 8 yielded the same 140kDa RNAP II-LS fragment observed in vivo. Using site-directed mutagenesis, the RNAP II-LS cleavage site was localized to an LETD sequence ending at residue 1339, which is near its C-terminal domain.
Lu
Yi
Y
Department of Pathology, Albert Einstein College of Medicine, F512, 1300 Morris Park Ave., Bronx, NY 10461, USA.
Luo
Zhonghui
Z
Bregman
David B
DB
D017209:Apoptosis; D001665:Binding Sites; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002945:Cisplatin / Q000494:pharmacology; D018736:DNA Adducts; D004249:DNA Damage; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D019169:Jurkat Cells; D008214:Lymphocytes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000378:metabolism*; D009418:S100 Proteins / Q000378:metabolism; D014162:Transfection; D014466:Ultraviolet Rays
D018736:DNA Adducts; D009418:S100 Proteins; D012319:RNA Polymerase II; C410949:RNA polymerase II largest subunit; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D002945:Cisplatin