JAK kinases control IL-5 receptor ubiquitination, degradation, and internalization

Biology of Inflammation Center and Immunology, Allergy and Rheumatology Section, Department of Medicine, Baylor College of Medicine, One Baylor Plaza, BCM 285, Houston, TX 77030-3411, USA.
Journal of Leukocyte Biology (Impact Factor: 4.29). 05/2007; 81(4):1137-48. DOI: 10.1189/jlb.0706465
Source: PubMed


IL-5, IL-3, and GM-CSF are related hematopoietic cytokines, which regulate the function of myeloid cells and are mediators of the allergic inflammatory response. These cytokines signal through heteromeric receptors containing a specific alpha chain and a shared signaling chain, betac. Previous studies demonstrated that the ubiquitin (Ub) proteasome degradation pathway was involved in signal termination of the betac-sharing receptors. In this study, the upstream molecular events leading to proteasome degradation of the IL-5 receptor (IL-5R) were examined. By using biochemical and flow cytometric methods, we show that JAK kinase activity is required for betac ubiquitination and proteasome degradation but only partially required for IL-5R internalization. Furthermore, we demonstrate the direct ubiquitination of the betac cytoplasmic domain and identify lysine residues 566 and 603 as sites of betac ubiquitination. Lastly, we show that ubiquitination of the betac cytoplasmic domain begins at the plasma membrane, increases after receptor internalization, and is degraded by the proteasome after IL-5R internalization. We propose an updated working model of IL-5R down-regulation, whereby IL-5 ligation of its receptor activates JAK2/1 kinases, resulting in betac tyrosine phosphorylation, ubiquitination, and IL-5R internalization. Once inside the cell, proteasomes degrade the betac cytoplasmic domain, and the truncated receptor complex is terminally degraded in the lysosomes. These data establish a critical role for JAK kinases and the Ub/proteasome degradation pathway in IL-5R down-regulation.

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Available from: Jonathan Thomas Lei, Apr 22, 2015
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    • "The common beta chain shared by the cognate receptors for interleukin‐3, interleukin‐5, and the granulocyte‐macrophage colony‐stimulating factor was shown to be ubiquitinated, internalized, and degraded in a manner dependent on activity of associated JAK2 [Martinez‐Moczygemba and Huston, 2001] and, perhaps, of JAK1 that is associated with the interleukin‐5‐specific alpha chain [Martinez‐Moczygemba et al., 2007]. Similarly to the JAK‐inducible IFNAR1 ubiquitination [Kumar et al., 2007], specific ubiquitin‐ acceptor sites appear to be responsible for the downregulation of common chain induced by interleukin‐5 [Lei et al., 2011]. "
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    ABSTRACT: Activation of cytokine receptor-associated Janus kinases (JAKs) mediates most, if not all, of the cellular responses to peptide hormones and cytokines. Consequently, JAKs play a paramount role in homeostasis and immunity. Members of this family of tyrosine kinases control the cytokine/hormone-induced alterations in cell gene expression program. This function is largely mediated through an ability to signal towards activation of the signal transducer and activator of transcription proteins (STAT) as well as towards some other pathways. Importantly, JAKs are also instrumental in tightly controlling the expression of associated cytokine and hormone receptors, and, accordingly, in regulating the cell sensitivity to these cytokines and hormones. This review highlights the enzymatic and non-enzymatic mechanisms of this regulation and discusses the importance of the ambidextrous nature of JAK as a key signaling node that integrates the combining the functions of forward signaling and eliminative signaling. Attention to the latter aspect of JAK function may contribute to emancipating our approaches to the pharmacologic modulation of JAKs. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.
    Journal of Cellular Biochemistry 01/2014; 115(1). DOI:10.1002/jcb.24647 · 3.26 Impact Factor
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    • "Delineating the biology of these cytokines is enabling the development of new strategies for diagnosing and treating these diseases and modulating immune responses. [13] It has been reported that recombinant human granulocyte-macrophage colonystimulating factor (rhGM-CSF), applied as a solution or an emulsion, improves wound healing. In order to confirm these data, the wound-healing efficacy of this growth factor was studied in a murine model. "
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    ABSTRACT: Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) is one of the several naturally occurring glycoproteins that regulate leukocyte production, migration and function. It has been produced in different cell types and with different properties based on the production process. The objective of this work is to carry out the site-directed mutagenesis (in-silico analysis) in human Granulocyte Macrophage Colony Stimulating Factor in order to increase the stability and half-life of this protein without affecting its biological activity. Among the other GM-CSF’s, Murine GM-CSF is the most stable form. Hence in this work, sequential analysis of the murine and human GM-CSF was performed in detail to understand the differences in the stability. It was found that the sialic acid content increased the half life of GM-CSF. Based on phylogenetic analysis and the information about the interaction of sialic acid, number of point mutations with Glutamic Acid (Glu), Asparagine (Asn), Arginine (Arg) were implemented at position 78 (Threonine-Thr) of hGMCSF and studied the effect of these mutations using Bio-Informatics tools. Energy minimisation studies were carried out to identify the stability. These studies revealed the potential advantages of using Arg to increase the stability. Further, using Bio-Informatics tools such as PatchDock, Argus Lab and Hex the mutated GM-CSF was docked and analyzed for the bio-activity of hGMCSF. The Arg mutation showed no change in the bioactivity. This Arg (-78) mutated GM-CSF can be confirmed for stability and biological activity using site- directed mutagenesis, in-vitro and in-vivo experiments.
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