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Selection-subtraction approach (SSA): a universal genetic screening technique that enables negative selection
Aatur D Singhi1, Roman V Kondratov, Nickolay Neznanov
1Department of Molecular Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Summary
This study introduces a novel selection-subtraction approach (SSA) to identify genes that inhibit or promote mammalian cell growth. SSA enables the discovery of previously hidden growth-modulating genetic elements.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Traditional screening methods for bioactive clones are limited to positive selections.
- These methods cannot identify genetic elements that suppress or cause lethality in mammalian cells.
- A need exists for methods that can detect a broader range of growth-modulating clones.
Purpose of the Study:
- To develop a novel technique, the selection-subtraction approach (SSA), for isolating growth-modulating clones.
- To enable the discovery of both growth-promoting and growth-suppressing genetic elements.
- To demonstrate the utility of SSA for gene discovery, target identification, and mutant protein generation.
Main Methods:
- Developed SSA utilizing tagged retroviral libraries in bacteriophage lambda vectors (retrophages).
- Employed nylon prints of retrophage libraries to quantify tag abundance in transduced cells.
- Assessed alterations in relative tag abundance to identify biological activity of individual clones.
Main Results:
- Successfully demonstrated the application of SSA for isolating growth-modulating clones.
- Used p53 and ataxia telangiectasia mutated (ATM) as models to identify growth inhibitory proteins, peptides, and antisense RNAs.
- Generated temperature-sensitive mutant proteins using the SSA technique.
Conclusions:
- SSA is an effective method for discovering genetic elements that modulate mammalian cell growth, including inhibitory ones.
- The technique facilitates gene discovery, target identification, and the generation of functional mutant proteins.
- SSA expands the scope of expression library screening beyond positive selection.