Identification of a novel septin 4 protein binding to human herpesvirus 8 kaposin A protein using a phage display cDNA library.
Human herpesvirus 8 (HHV-8) is associated with the development of Kaposi's sarcoma and several other human malignancies. Kaposin A protein of HHV-8 has been demonstrated as inducing tumorigenic transformation, being responsible for nuclear receptor coactivators in the transforming activity. In this study, a kaposin A-interacting septin 4 variant that contained the unique GDR at the N-terminus and AAALE at the C-terminus was identified using affinity selection of a phage display library. Co-immunoprecipitation and confocal imaging revealed in vitro binding specificity and in vivo co-localization of HHV-8 kaposin A protein to the septin 4 variant. The kaposin A-interacting septin 4 variant induced cell rounding up, activated caspase-3, and up-regulated transcriptional factor NF-kappaB. By contrast, kaposin A protein showed an antagonistic effect on the biological functions of the septin 4 variant. Therefore, the interaction of kaposin A protein and the septin 4 variant was suggested as playing a possible role in the development of HHV-8-associated malignancies. This study provides insights into the mechanism of the kaposin A protein pathology, in which the interactions of kaposin A protein with cellular proteins might allow alteration of fundamental cellular processes.
Lin
Cheng-Wen
CW
Department of Medical Laboratory Science and Biotechnology, China Medical University, No. 91, Hsueh-Shih Road, Taichung 404, Taiwan. cwlin@mail.cmu.edu.tw
Tu
Ping-Feng
PF
Hsiao
Nai-Wan
NW
Chang
Ching-Yao
CY
Wan
Lei
L
Lin
Yu-Tsun
YT
Chang
Hsueh-Wei
HW
D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism*; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism*; D019288:Herpesvirus 8, Human / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000378:metabolism; D019151:Peptide Library; D011994:Recombinant Proteins; D012514:Sarcoma, Kaposi; D058112:Septins; D015398:Signal Transduction; D015854:Up-Regulation; D014764:Viral Proteins / Q000302:isolation & purification* / Q000378:metabolism*
D003598:Cytoskeletal Proteins; D016328:NF-kappa B; D019151:Peptide Library; D011994:Recombinant Proteins; D014764:Viral Proteins; C120136:kaposin B protein, Human herpesvirus 8; D053148:Caspase 3; D020558:GTP Phosphohydrolases; C492027:SEPTIN4 protein, human; D058112:Septins