RESUMO
We have previously shown the delivery of phosphatase of regenerating liver-1 (PRL-1) to the immunological synapse (IS) and proposed a regulatory role of the catalytic activity of PRLs (PRL-1, PRL-2 and PRL-3) in antigen-induced IL-2 production. Nonetheless, the expression in T cells and delivery to the IS of the highly homologous PRL-3, as well as the role of the catalytic activity of PRLs in antigen-induced early signaling, has not been investigated. Here, the expression of PRL-3 protein was detected in primary CD4 T cells and in the CD4 T cell line Jurkat (JK), in which an overexpressed GFP-PRL-3 fluorescent fusion protein trafficked through the endosomal recycling compartment and co-localized with PLCγ1 signaling sites at the IS. Pharmacological inhibition was used to compare the role of the catalytic activity of PRLs in antigen-induced early signaling and late IL-2 production. Although the phosphatase activity of PRLs was not critical for early signaling triggered by antigen, it seemed to regulate signaling dynamics and was necessary for proper IL-2 production. We propose that enzymatic activity of PRLs has a higher significance for cytokine production than for early signaling at the IS. However, further research will be necessary to deeply understand the regulatory role of PRLs during lymphocyte activation and effector function.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Interleucina-2/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais , Linfócitos T CD4-Positivos/efeitos dos fármacos , Células Cultivadas , Endossomos/metabolismo , Inibidores Enzimáticos/farmacologia , Humanos , Iminas/farmacologia , Interleucina-2/genética , Células Jurkat , Ativação Linfocitária , Proteínas de Neoplasias/antagonistas & inibidores , Fosfolipase C gama/metabolismo , Proteínas Tirosina Fosfatases/antagonistas & inibidores , Piridinas/farmacologiaRESUMO
Twenty-seven diterpenes, including abietanes, labdanes, abeoabietanes, halimanes, and pimaranes, have been evaluated against epimastigote and intracellular amastigote forms of Trypanosoma cruzi and also against LC5 and NCTC cell lines. Royleanones (3, 4, and 5) and a further abietane (12), obtained by purification of Plectranthus spp. extracts, were the most active compounds on epimastigotes, showing IC50 values similar (1.73 µg/mL, 12) or even lower (0.39, 0.99, and 1.20 µg/mL, 3, 4, and 5 respectively) than the positive control nifurtimox (2.3 µg/mL). On intracellular amastigotes, abietanes 3, 4, and 5 showed a significant activity with IC50 values of 0.83, < 0.31, and 0.62 µg/mL, respectively, but were less potent than the positive control nifurtimox (IC50 < 0.16 µg/mL). Compounds 3, 4, and 5 were not cytotoxic to LC5 and NCTC 929 cells at 1 µg/mL.
Assuntos
Antiparasitários/farmacologia , Diterpenos/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Antiparasitários/química , Linhagem Celular , Diterpenos/química , Humanos , Concentração Inibidora 50 , Camundongos , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Plectranthus/químicaRESUMO
Actin dynamics control early T-cell receptor (TCR) signalling during T-cell activation. However, the precise regulation of initial actin rearrangements is not completely understood. Here, we have investigated the regulatory role of the phosphatase Slingshot-1 (SSH1) in this process. Our data show that SSH1 rapidly polarises to nascent cognate synaptic contacts and later relocalises to peripheral F-actin networks organised at the mature immunological synapse. Knockdown of SSH1 expression by CRISPR/Cas9-mediated genome editing or small interfering RNA reveal a regulatory role for SSH1 in CD3ε conformational change, allowing Nck binding and proper downstream signalling and immunological synapse organisation. TCR triggering induces SSH1-mediated activation of actin dynamics through a mechanism mediated by Limk-1 inactivation. These data suggest that during early TCR activation, SSH1 is required for rapid F-actin rearrangements that mediate initial conformational changes of the TCR, integrin organisation and proximal signalling events for proper synapse organisation. Therefore, the SSH1 and Limk-1 axis is a key regulatory element for full T cell activation.
Assuntos
Quinases Lim , Fosfoproteínas Fosfatases , Receptores de Antígenos de Linfócitos T , Humanos , Quinases Lim/metabolismo , Quinases Lim/genética , Receptores de Antígenos de Linfócitos T/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Fosfoproteínas Fosfatases/genética , Actinas/metabolismo , Actinas/genética , Ativação Linfocitária , Células Jurkat , Linfócitos T/metabolismo , Linfócitos T/imunologia , Transdução de Sinais , Sinapses Imunológicas/metabolismoRESUMO
T cell activation and effector function is mediated by the formation of a long-lasting interaction established between T cells and antigen-presenting cells (APCs) called immunological synapse (IS). During T cell activation, different signaling molecules as well as the cytoskeleton and the endosomal compartment are polarized to the IS. This molecular dynamics is tightly regulated by phosphorylation networks, which are controlled by protein tyrosine phosphatases (PTPs). While some PTPs are known to be important regulators of adhesion, ligand discrimination or the stimulation threshold, there is still little information about the regulatory role of PTPs in cytoskeleton rearrangements and endosomal compartment dynamics. Besides, spatial and temporal regulation of PTPs and substrates at the IS is only barely known. Consistent with an important role of PTPs in T cell activation, multiple mutations as well as altered expression levels or dynamic behaviors have been associated with autoimmune diseases. However, the precise mechanism for the regulation of T cell activation and effector function by PTPs in health and autoimmunity is not fully understood. Herein, we review the current knowledge about the regulatory role of PTPs in CD4+ T cell activation, IS assembly and effector function. The potential molecular mechanisms mediating the action of these enzymes in autoimmune disorders are discussed.
Assuntos
Doenças Autoimunes/imunologia , Linfócitos T CD4-Positivos/imunologia , Comunicação Celular/imunologia , Ativação Linfocitária , Proteínas Tirosina Fosfatases/imunologia , Transdução de Sinais/imunologia , Doenças Autoimunes/patologia , Linfócitos T CD4-Positivos/fisiologia , HumanosRESUMO
The regulatory role of most dual specific phosphatases during T cell activation remains unknown. Here, we have studied the expression and function of phosphatases of regenerating liver (PRLs: PRL-1, PRL-2, and PRL-3) during T cell activation, as well as, the dynamic delivery of PRL-1 to the Immunological Synapse (IS). We found that T cell activation downregulates the expression of PRL-2, resulting in an increased PRL-1/PRL-2 ratio. PRL-1 redistributed at the IS in two stages: Initially, it was transiently accumulated at scanning membranes enriched in CD3 and actin, and at later times, it was delivered at the contact site from pericentriolar, CD3ζ-containing, vesicles. Once at the established IS, PRL-1 distributed to LFA-1 and CD3ε sites. Remarkably, PRL-1 was found to regulate actin dynamics during IS assembly and the secretion of IL-2. Moreover, pharmacological inhibition of the catalytic activity of the three PRLs reduced the secretion of IL-2. These results provide evidence indicating a regulatory role of PRL-1 during IS assembly and highlight the involvement of PRLs in immune responses by mature T cells.
Assuntos
Actinas/imunologia , Proteínas de Ciclo Celular/imunologia , Sinapses Imunológicas/imunologia , Ativação Linfocitária , Proteínas de Membrana/imunologia , Proteínas Tirosina Fosfatases/imunologia , Linfócitos T/imunologia , Complexo CD3/imunologia , Feminino , Humanos , Interleucina-2/imunologia , Antígeno-1 Associado à Função Linfocitária/imunologia , MasculinoRESUMO
A phytochemical study of an extract from transformed root cultures of Nepeta teydea, induced by Agrobacterium rhizogenes, led to the isolation of the following new compounds: the sesquiterpene (-)-cinalbicol, the diterpene teydeadione (6,11,14-trihydroxy-12-methoxy-abieta-5,8,11,13,15-penten-7-one), a degraded C23-triterpene (teydealdehyde) and three fatty acid esters of lanosta-7,24-dien-3ß-ol. The propyl ester of rosmarinic acid was also isolated for the first time from a natural source. In addition, two dehydroabietane diterpenes, eight triterpenes and eighteen known phenolic compounds were obtained. The antifeedant, cytotoxic and phytotoxic activities of the isolated compounds have also been investigated.