Streptogramin- and tetracycline-responsive dual regulated expression of p27(Kip1) sense and antisense enables positive and negative growth control of Chinese hamster ovary cells.
We constructed a dual regulated expression vector cassette (pDuoRex) whereby two heterologous genes can be independently regulated via streptogramin- and tetracycline-responsive promoters. Two different constructs containing growth-promoting and growth-inhibiting genes were stably transfected in recombinant Chinese hamster ovary (CHO) cells that express the streptogramin- and tetracycline-dependent transactivators in a dicistronic configuration. An optimally balanced heterologous growth control scenario was achieved by reciprocal expression of the growth-inhibiting human cyclin-dependent kinase inhibitor p27(Kip1) in sense (p27(Kip1)S) and antisense (p27(Kip1)AS) orientation. Exclusive expression of p27(Kip1)S resulted in complete G(1)-phase-specific growth arrest, while expression of only p27(Kip1)AS showed significantly increased proliferation compared to control cultures (both antibiotics present), presumably by decreasing host cell p27(Kip1) expression. In a second system, a derivative of pDuoRex encoding streptogramin-responsive expression of the growth-promoting SV40 small T antigen (sT) and tetracycline-regulated expression of p27(Kip1) was stably transfected into CHO cells. Expression of sT alone resulted in an increase in cell proliferation, but the expression of p27(Kip1) failed to provide the expected G(1)-specific growth arrest despite having demonstrated expression of the protein. This illustrates the difficulty in balancing the complex pathways underlying cell proliferation control through the expression of two functionally distinct genes involved in those pathways, and how a single-gene sense/antisense approach using pDuoRex can overcome this barrier to complete metabolic engineering control.
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Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zurich, Switzerland.
Moser
S
S
Schlatter
S
S
Rimann
M
M
Bailey
J E
JE
Fussenegger
M
M
D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects*; D006224:Cricetinae; D050760:Cyclin-Dependent Kinase Inhibitor p27; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D007700:Kinetics; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D016372:RNA, Antisense / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology*; D014162:Transfection; D025521:Tumor Suppressor Proteins; D014769:Virginiamycin / Q000494:pharmacology*
D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; D016372:RNA, Antisense; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D014769:Virginiamycin; D050760:Cyclin-Dependent Kinase Inhibitor p27; D013752:Tetracycline