Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.16 (calcineurin)
 17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sustained calcium signaling induces a state of anergy or antigen unresponsiveness in T cells, mediated through calcineurin and the transcription factor NFAT. We show here that Ca(2+)-induced anergy is a multistep program that is implemented at least partly through proteolytic degradation of specific signaling proteins. Calcineurin increased mRNA and protein of the E3 ubiquitin ligases Itch, Cbl-b and GRAIL and induced expression of Tsg101, the ubiquitin-binding component of the ESCRT-1 endosomal sorting complex. Subsequent stimulation or homotypic cell adhesion promoted membrane translocation of Itch and the related protein Nedd4, resulting in degradation of two key signaling proteins, PKC-theta and PLC-gamma1. T cells from Itch- and Cbl-b-deficient mice were resistant to anergy induction. Anergic T cells showed impaired calcium mobilization after TCR triggering and were unable to maintain a mature immunological synapse, instead showing late disorganization of the outer ring containing lymphocyte function-associated antigen 1. Our results define a complex molecular program that links gene transcription induced by calcium and calcineurin to a paradoxical impairment of signal transduction in anergic T cells.
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PMID:Calcineurin imposes T cell unresponsiveness through targeted proteolysis of signaling proteins. 1498 8

Acquisition of the anergy phenotype in T cells is blocked by inhibitors of protein synthesis and calcineurin activity, suggesting that anergic T cells may have a unique genetic program. Retroviral transduction of hemopoietic stem cells from TCR transgenic mice and subsequent reconstitution of syngeneic mice to express the E3 ubiquitin ligase, gene related to anergy in lymphocytes (GRAIL), or an enzymatically inactive form, H2N2 GRAIL, allowed analysis of the role of GRAIL in T cell anergy in vivo. Constitutive expression of GRAIL was sufficient to render naive CD4 T cells anergic, however, when the enzymatically inactive form H2N2 GRAIL was expressed, it functioned as a dominant negative of endogenous GRAIL and blocked the development of anergy. These data provide direct evidence that a biochemical pathway composed of GRAIL and/or GRAIL-interacting proteins is important in the development of the CD4 T cell anergic phenotype in vivo.
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PMID:The gene related to anergy in lymphocytes, an E3 ubiquitin ligase, is necessary for anergy induction in CD4 T cells. 1521 Jul 61

The ubiquitination system comprises a highly specific and regulated post-translational mechanism by which the immune response can be modulated, setting the balance between immunity and tolerance. Proteolysis dependent and independent mechanisms have been implicated. Particularly, the role of ubiquitin ligases as modulators of central and peripheral tolerance has brought attention to this system as one of the key elements of a complex regulatory network designed to maintain an active surveillance system. Cbl-b, GRAIL and Itch are the main E3 ligases, considered as negative regulators of the immune response as part of the genetic program induced by the calcium/calcineurin pathway. Other key signaling pathways for the immune response, such as the NF-kappaB and TGF-beta signaling are prone to be modulated by these ubiquitin ligases. Diverse mechanisms have been implicated in the development of anergy associated to E3 ligases, among these, the setting for TCR responsiveness and repression of cytokine transcription are best well characterized. Also, a role as inductors of regulatory T cells has been evidenced for Cbl-b and GRAIL. The defective expression of some of these E3 ligases has been related to the development of autoimmune disease, in experimental murine and human models, remarking its possible pathogenic role.
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PMID:Ubiquitination system and autoimmunity: the bridge towards the modulation of the immune response. 1829 31