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A death-promoting role for ISG54/IFIT2
1Department of Molecular Genetics and Microbiology, Stony Brook University , Stony Brook, NY 11794, USA. nreich@notes.cc.sunysb.edu
Abstract:
The cellular responses to infection are many, and include programmed cell death to inhibit microbial dissemination and the production and secretion of interferons (IFNs), which confer resistance to uninfected cells. In addition to the antimicrobial effects of IFNs, these cytokines have been used clinically for the treatment of various neoplasias to inhibit proliferation and stimulate apoptosis. However, the precise mechanisms of action of IFNs remain to be completely understood. One of the primary response genes induced after an infection or treatment with type I or III IFN is known as IFN-stimulated gene 54 (ISG54) or IFN-induced gene with tetratricopeptide repeats 2 (IFIT2). ISG54/IFIT2 is a member of a family of IFN-induced genes related in the sequence and structure. Expression of this protein has been found to promote cellular apoptosis by a mitochondrial pathway dependent on the action of Bcl2 proteins. ISG54/IFIT2 does not function as a monomer, and it forms complexes with itself and with the related ISG56/IFIT1 and ISG60/IFIT3 proteins to elicit complex cellular responses. The apoptotic response to ISG54/IFIT2 may contribute to other functions that have been reported, including translational regulation, inhibition of tumor colonization, and protection against a lethal viral infection.
Insights
Interferons (IFNs) trigger cellular apoptosis via ISG54/IFIT2, a key protein that forms complexes to regulate cell death and other functions. This mechanism is crucial for antiviral defense and has implications for cancer therapy.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Cellular responses to infection include programmed cell death and interferon (IFN) production.
- IFNs are cytokines used clinically for cancer treatment due to their antiproliferative and pro-apoptotic effects.
- The exact mechanisms of IFN action require further elucidation.
Purpose of the Study:
- To investigate the role of IFN-stimulated gene 54 (ISG54)/IFN-induced gene with tetratricopeptide repeats 2 (IFIT2) in cellular responses.
- To understand the apoptotic pathway mediated by ISG54/IFIT2.
- To explore the functional complexes formed by ISG54/IFIT2.
Main Methods:
- Analysis of gene expression following IFN treatment.
- Investigation of protein-protein interactions involving ISG54/IFIT2.
- Assessment of apoptosis induction via mitochondrial pathways and Bcl2 proteins.
Main Results:
- ISG54/IFIT2 is a primary response gene induced by type I or III IFNs.
- ISG54/IFIT2 expression promotes apoptosis through a Bcl2-dependent mitochondrial pathway.
- ISG54/IFIT2 functions as part of a complex with itself and related proteins (ISG56/IFIT1, ISG60/IFIT3).
Conclusions:
- ISG54/IFIT2 plays a significant role in IFN-mediated apoptosis.
- The apoptotic function of ISG54/IFIT2 may underlie its roles in translational regulation, tumor inhibition, and viral protection.
- Understanding ISG54/IFIT2 mechanisms offers insights into both immune responses and therapeutic applications.
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