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Cellular Transforming Processes Sensed by Apoptin. Dongjun Peng. Dept. of Biological Chemistry, LIC Leiden University, The Netherlands Dept. of Biochemistry & Molecular Biology Tongji Medical College, HUST, Wuhan, China. CAV. in human tumor cells. Apoptin. Phosphorylation.
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Cellular Transforming Processes Sensed by Apoptin Dongjun Peng Dept. of Biological Chemistry, LIC Leiden University, The Netherlands Dept. of Biochemistry & Molecular Biology Tongji Medical College, HUST, Wuhan, China
CAV in human tumor cells Apoptin Phosphorylation in human normal cells dead alive
Normal cells Apoptosis Model system: SV40 T antigen induces transforming processes N localization + SV40-T apoptin apoptin apoptin Phosphorylation apoptin + SV40-T apoptin P-apoptin SV40-T antigen can be used to identify the cellular factors involved in apoptin activation
LT p53 binding 708aa SV40 LT/st harbors transforming domains targeting cellular factors N-terminal of LT/st is sufficient for apoptin’s activation Rb binding 136aa J LT136 nls Hsc70 binding st unique J 174aa st PP2A binding
124aa Rb J LT 124 Rb binding domain mutation PP2A 174aa st J binding 136aa Rb J LT 136 nls LT124/st/nls- LT124/st/nls-/Rb- PP2A 174aa st J LT136/st/Rb- binding Is nuclear targeting of LT136/st important? LT136/st Control • Rb is only involved in bringing LT/st into nucleus • Nuclear targeting is essential P-apoptin apoptin
136aa 136aa J LT 136 J LT 136 nls nls LT136 + st LT136/st Control LT136 st P-apoptin apoptin st LT136 Are both LT136 and st of importance? PP2A 174aa st J binding Both LT136 and st are needed for optimal activation of apoptin
136aa 136aa 136aa 136aa 136aa 136aa Rb Rb Rb J J J J J J LT LT LT LT LT LT 136 136 136 136 136 136 binding binding binding nls nls nls nls nls nls + + + + + + PP2A PP2A PP2A PP2A PP2A PP2A 174aa 174aa 174aa 174aa 174aa 174aa st st st st st st J J J J J J binding binding binding binding binding binding LT136 D44N + st D44N LT136 D44N + st LT136 + st D44N LT136+st P-apoptin apoptin st LT136 Is the J domain important for apoptin’s activation? D44N mutation in J domain Both J-domains are involved in apoptin activation
C103S Strep-LT136/st C103S Strep-LT136/st LT136/st C103S Input LT136/st Control F9 A (PP2A) P-apoptin st apoptin LT136 st Actin LT136 Is the PP2A binding domain in st crucial?
Nuclear presence of both J domain & PP2A binding domain are crucial for activation of tumor-related kinase Recently: Both the J domain & PP2A binding domain of st contact and inactivate PP2A Chen Y, 2007, Nat Struct Mol Biol Cho US, 2007, PLoS Biology
Is inactivation of PP2A sufficient to activate apoptin’s tumor-related kinase? RNAi analysis control B56- RNAi B56 P-apoptin apoptin
Inactivation of PP2A’s regulatory subunit B56γ is sufficient to activate apoptin’s tumor-related kinase
Acknowledgement • Dept. of Biological Chemistry in University Leiden • Mathieu Noteborn • Maarten de Smit • Patrick Voskamp • Rhyenne Zimmerman • Dept. of Molecular Genetics in University Leiden • Claude Backendorf • Ying-Hui Zhang • Wilbert Vermeij • University of Pittsburgh • James Pipas KNAW Leiden Institute of Chemistry Tongji Medical College