Albumin fibrillization induces apoptosis via integrin/FAK/Akt pathway.
BACKGROUND
Numerous proteins can be converted to amyloid-like fibrils to increase cytotoxicity and induce apoptosis, but the methods generally require a high concentration of protein, vigorous shaking, or fibril seed. As well, the detailed mechanism of the cytotoxic effects is not well characterized. In this study, we have developed a novel process to convert native proteins into the fibrillar form. We used globular bovine serum albumin (BSA) as a model protein to verify the properties of the fibrillar protein, investigated its cellular effects and studied the signaling cascade induced by the fibrillar protein.


RESULTS
We induced BSA, a non-cytotoxic globular protein, to become fibril by a novel process involving Superdex-200 column chromatography in the presence of anionic or zwittergenic detergent(s). The column pore size was more important than column matrix composite in fibril formation. The fibrillar BSA induced apoptosis in BHK-21 cell as well as breast cancer cell line T47D. Pre-treating cells with anti-integrin antibodies blocked the apoptotic effect. Fibrillar BSA, but not globular BSA, bound to integrin, dephosphorylated focal adhesion kinase (FAK), Akt and glycogen synthase kinase-3beta (GSK-3beta).


CONCLUSIONS
We report on a novel process for converting globular proteins into fibrillar form to cause apoptosis by modulating the integrin/FAK/Akt/GSK-3beta/caspase-3 signaling pathway. Our findings may be useful for understanding the pathogenesis of amyloid-like fibrils and applicable for the development of better therapeutic agents that target the underlying mechanism(s) of the etiologic agents.
Huang
Chun-Yung
CY
Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan. l6892106@ccmail.ncku.edu.tw
Liang
Chi-Ming
CM
Chu
Chiao-Li
CL
Liang
Shu-Mei
SM
D000818:Animals; D017209:Apoptosis; D002417:Cattle; D045744:Cell Line, Tumor; D002850:Chromatography, Gel; D006224:Cricetinae; D003902:Detergents; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000378:metabolism*
D003902:Detergents; D016023:Integrins; D012710:Serum Albumin, Bovine; D051416:Focal Adhesion Protein-Tyrosine Kinases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3