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Published on: July 21, 2014
Identification and characterization of genes responsive to apoptosis: application of DNA chip technology and mRNA
1Department of Molecular Biology, Pfizer Global Research and Development, Ann Arbor, MI 48105, USA. yi.sun@wl.com
Abstract:
Apoptosis (programmed cell death) is a genetically programmed active cell death process for maintaining homeostasis under physiological conditions and for responding to various stimuli. Many human diseases have been associated with either increased apoptosis (such as AIDS and neurodegenerative disorders) or decreased apoptosis (such as cancer and autoimmune disorders). In an attempt to understand apoptosis signaling pathway and genes associated with apoptosis, we established two cell model systems on which apoptosis is induced either by DNA damaging agent, etoposide or by redox agent, 1,10-phenanthroline (OP). DNA chip profiling or mRNA differential display (DD) was utilized to identify genes responsive to apoptosis induced by these two agents. In etoposide model with chip hybridization, we defined signaling pathways that mediate apoptosis in p53 dependent manner (through activation of p53 target genes such as Waf-1/p21, PCNA, GPX, S100A2 and PTGF-beta) as well as in p53-independent manner (through activation of ODC and TGF-beta receptor, among others). In OP model with DD screening, we cloned and characterized two genes: glutathione synthetase, encoding an enzyme involved in glutathione synthesis and Sensitive to Apoptosis Gene (SAG), a novel evolutionarily conserved gene encoding a zinc RING finger protein. Both genes appear to protect cells from apoptosis induced by redox agents. Further characterization of SAG revealed that it is a growth essential gene in yeast and belongs to a newly identified gene family that promotes protein ubiquitination and degradation. Through this activity, SAG regulates cell cycle progression and many other key biological processes. Thus, SAG could be a valid drug target for anti-cancer and anti-inflammation therapies.
Insights
Researchers identified genes regulating apoptosis, or programmed cell death, using etoposide and redox agents. The Sensitive to Apoptosis Gene (SAG) protects cells from redox-induced apoptosis and may be a therapeutic target.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Apoptosis, or programmed cell death, is crucial for homeostasis and implicated in diseases like cancer and AIDS.
- Dysregulation of apoptosis contributes to various human pathologies.
Purpose of the Study:
- To identify genes and signaling pathways involved in apoptosis.
- To understand the mechanisms of apoptosis induced by DNA damage and redox agents.
Main Methods:
- Established etoposide (DNA damaging agent) and 1,10-phenanthroline (redox agent) induced apoptosis models.
- Utilized DNA chip profiling and mRNA differential display (DD) to identify responsive genes.
Main Results:
- Defined p53-dependent and p53-independent apoptosis pathways in the etoposide model.
- Cloned and characterized glutathione synthetase and Sensitive to Apoptosis Gene (SAG) in the redox model.
- SAG protects cells from redox-induced apoptosis and regulates cell cycle via protein ubiquitination.
Conclusions:
- Identified key genes and pathways regulating apoptosis.
- SAG is a novel, evolutionarily conserved gene protecting against redox-induced apoptosis.
- SAG represents a potential drug target for anti-cancer and anti-inflammation therapies.
