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Janus kinases and their role in growth and disease
M Aringer1, A Cheng, J W Nelson
1Lymphocyte Biology Section, Arthritis and Rheumatism Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892-1820, USA.
Abstract:
Janus kinases (JAK) play a crucial role in the initial steps of cytokine signaling. Each of the four members (JAK1, JAK2, JAK3, TYK2) of this non-receptor tyrosine kinase family is indispensable for the effects of distinct cytokines. Moreover, recent reports have added to our knowledge on their highly specific functions: JAK3 knockout mice and JAK3 deficient patients cannot signal through the interleukin-2,4,7,9, or 15 receptors and suffer from severe combined immunodeficiency (SCID). JAK1 and JAK2 knockout mice do not survive, their cells again showing distinct patterns of cytokine signaling deficits. At the other end of the spectrum, JAK fusion proteins have been shown to play a role in leukemias. In addition, a new class of JAK-specific inhibitors was described by several groups, the CIS/SOCS/Jab family. This review on the rapidly growing field focuses on JAK function and regulation, and on their emerging role in development and human disease.
Insights
Janus kinases (JAKs) are vital for cytokine signaling. This review explores their specific roles in immunity, development, and diseases like leukemia, highlighting new inhibitors.
Area of Science:
- Biochemistry
- Immunology
- Molecular Biology
Background:
- Janus kinases (JAKs) are critical non-receptor tyrosine kinases involved in cytokine signaling pathways.
- The JAK family comprises JAK1, JAK2, JAK3, and TYK2, each essential for distinct cytokine receptor signaling.
- Dysregulation of JAK signaling is implicated in various human diseases, including immunodeficiency and leukemia.
Purpose of the Study:
- To review the specific functions and regulation of Janus kinases (JAKs).
- To highlight the emerging roles of JAKs in biological development and human diseases.
- To discuss the implications of JAK-specific inhibitors.
Main Methods:
- Literature review of recent findings on JAK function, regulation, and disease association.
- Analysis of data from knockout mouse models and human patient studies.
- Examination of newly identified JAK-specific inhibitor families, such as CIS/SOCS/Jab.
Main Results:
- JAK3 deficiency leads to severe combined immunodeficiency (SCID) due to impaired signaling of specific interleukins.
- JAK1 and JAK2 knockout mice exhibit distinct cytokine signaling deficits and are non-viable.
- JAK fusion proteins are associated with leukemias, and specific JAK inhibitors are under development.
Conclusions:
- Janus kinases (JAKs) exhibit highly specific functions crucial for normal development and immune responses.
- Aberrant JAK signaling contributes to severe human diseases, including SCID and leukemias.
- JAKs represent promising therapeutic targets, with ongoing research into specific inhibitors for various conditions.