Transcriptional responses to polypeptide ligands: the JAK-STAT pathway
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1Department of Medicine, Columbia University Medical Center, New York, N.Y., USA.
Abstract:
Cytokines and growth factors regulate multiple aspects of cell growth through their interactions with specific receptors. These receptors initiate signals directed at both the cytoplasmic and the nuclear compartments. Many of the nuclear signals culminate in the induction of new genes. Characterization of the ability of IFN-alpha to rapidly induce new genes has led to the identification of a new signaling paradigm, the JAK-STAT (Signal Transducers and Activators of Transcription) pathway. In the IFN-alpha pathway, two receptor associated tyrosine kinases from the JAK family, Jak1 and Tyk2, mediate the activation of two latent cytoplasmic transcription factors, Stat1 and Stat2. More recent studies have not only determined that this pathway is used extensively, but have led to the identification of additional components (e.g., Jak2, Jak3, Stat3, Stat4, Stat5, and Stat6). This review will examine how these components mediate the transduction of signal directly from receptor to nucleus.
Insights
The JAK-STAT pathway, involving Janus kinases (JAK) and Signal Transducers and Activators of Transcription (STAT) proteins, rapidly transmits signals from cell receptors to the nucleus, inducing new genes. This review details the components and mechanisms of this crucial signaling pathway.
Area of Science:
- Cellular signaling
- Molecular biology
- Genetics
Background:
- Cytokines and growth factors regulate cell growth via receptors, initiating cytoplasmic and nuclear signals.
- Nuclear signals often lead to the induction of new genes.
- Interferon-alpha (IFN-alpha) rapidly induces genes, revealing the JAK-STAT signaling pathway.
Purpose of the Study:
- To review the identification and characterization of the JAK-STAT signaling pathway.
- To examine the components involved in signal transduction from receptor to nucleus.
- To elucidate the mechanism of gene induction mediated by this pathway.
Main Methods:
- Review of existing literature on IFN-alpha signaling.
- Identification of receptor-associated tyrosine kinases (JAK family).
- Characterization of latent cytoplasmic transcription factors (STAT family).
Main Results:
- The JAK-STAT pathway comprises JAK kinases (Jak1, Jak2, Jak3, Tyk2) and STAT proteins (Stat1-Stat6).
- This pathway mediates signal transduction from the cell surface receptor directly to the nucleus.
- IFN-alpha utilizes this pathway for rapid gene induction.
Conclusions:
- The JAK-STAT pathway is a critical signaling paradigm for cytokine and growth factor responses.
- Understanding the JAK-STAT pathway components is essential for comprehending cellular regulation.
- This pathway provides a direct link between receptor activation and nuclear gene expression.