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SOCS: suppressors of cytokine signalling
1Cooperative Research Centre for Cellular Growth Factors, Parkville, Vic., Australia. starr@wehi.edu.au
Abstract:
Regulation of many aspects of cell behaviour occurs through the interaction of cytokines with specific cell surface receptors, resulting in the activation of cytoplasmic signal transduction pathways. Although cellular responses to cytokines are tightly controlled, few molecules have been identified which are able to switch these signals off. The suppressors of cytokine signalling (SOCS) proteins are a new family of negative regulators of cytokine signal transduction. SOCS proteins contain a variable amino-terminal region, a central Src-homology 2 (SH2) domain and a novel conserved carboxy-terminal motif termed the SOCS box. The expression of SOCS proteins is induced by cytokine. Once expressed, SOCS downregulate JAK/STAT pathways and hence the biological response. Recent studies, primarily reliant on overexpression of proteins, indicate that SOCS may be involved in modulating additional pathways, suggesting that they may play a more general role in regulating cellular responses to cytokine. The analysis of knockout mice will clarify the physiological role of SOCS in regulating cytokine responsiveness. Mutations leading to the loss of SOCS activity may give rise to cytokine hyperresponsiveness and may contribute to the development of diseases such as diabetes and cancer. Small molecule effectors which modify SOCS function may potentially be useful therapeutics for the treatment of certain diseases.
Insights
Suppressors of cytokine signalling (SOCS) proteins are newly identified negative regulators of cytokine signal transduction. These proteins, induced by cytokines, downregulate JAK/STAT pathways, controlling cellular responses and potentially impacting diseases like cancer.
Area of Science:
- Cell Biology
- Immunology
- Molecular Biology
Background:
- Cytokine signaling regulates cell behavior via cell surface receptors and cytoplasmic pathways.
- Few molecules are known to inhibit cytokine signaling, necessitating identification of negative regulators.
- Suppressors of Cytokine Signalling (SOCS) proteins represent a novel class of negative regulators.
Purpose of the Study:
- To investigate the role of SOCS proteins in regulating cytokine signal transduction.
- To understand the molecular structure and function of SOCS proteins.
- To explore the potential involvement of SOCS in broader cellular responses and disease.
Main Methods:
- Analysis of SOCS protein structure, including SH2 domains and SOCS boxes.
- Investigating cytokine-induced expression of SOCS proteins.
- Examining the downregulation of JAK/STAT pathways by SOCS.
- Utilizing knockout mouse models to clarify physiological roles (proposed).
Main Results:
- SOCS proteins possess distinct structural domains (amino-terminal, SH2, SOCS box).
- SOCS protein expression is induced by cytokine stimulation.
- SOCS proteins effectively downregulate JAK/STAT signaling pathways.
- Preliminary evidence suggests SOCS may regulate additional signaling pathways.
Conclusions:
- SOCS proteins are critical negative regulators of cytokine signaling, primarily via JAK/STAT pathway inhibition.
- Further research, including knockout mouse studies, is needed to fully elucidate the physiological roles of SOCS.
- Dysregulation of SOCS activity may contribute to diseases like diabetes and cancer, suggesting therapeutic potential.