Dynamic equilibrium between calcineurin and kinase activities regulates the phosphorylation state and localization of the nuclear factor of activated T-cells

Abstract

The nuclear factor of activated T-cells (NFAT p ) is a phosphorylated transcription factor that resides in the cytoplasm of unactivated T-cells. T-cell activation results in the activation of the phosphatase calcineurin (CaN), which leads to the dephosphorylation and subsequent nuclear localization of NFAT p . We have investigated the role of kinases in the phosphorylation state and subcellular localization of NFAT p . The phosphorylation state and nuclear\cytoplasmic location of NFAT p were determined in unstimulated murine HT-2 cells treated with a panel of kinase inhibitors. Two of the seven kinase inhibitors, staurosporine (St) and bisindolylmaleimide I (BI), resulted in the dephosphorylation and nuclear localization of NFAT p . These Stinduced effects were inhibited by pretreatment with FK506,

Wnt-5a/Ca2+-Induced NFAT Activity Is Counteracted by Wnt-5a/Yes-Cdc42-Casein Kinase 1α Signaling in Human Mammary Epithelial Cells

“…The phosphorylated form of NFAT1 appears to have a molecular mass of approximately 135 kDa, whereas the active, dephosphorylated form, which is sequestered in the nucleus, is about 120 kDa (23,52,55). In line with our previous results we found that treatment with PP1 alone caused a slight activation of NFAT1 in both types of cells, an effect that was more pronounced in the Wnt-5a high cells (Fig.…”

Sustained Activation of N-Methyl-d-Aspartate Receptors in Podoctyes Leads to Oxidative Stress, Mobilization of Transient Receptor Potential Canonical 6 Channels, Nuclear Factor of Activated T Cells Activation, and Apoptotic Cell Death

“…Highly phosphorylated NFAT normally resides in the cytosol. However, TRPC6-mediated activation of calcineurin results in dephosphorylation of NFAT, causing some of it to translocate to the nucleus where it can regulate gene expression (Scott et al, 1997;Kuwahara et al, 2006). Using an assay based on cell fractionation, we observed that 100 M NMDA treatment for 24 h caused a marked increase in the amount of NFAT that is located in nuclei (a cell fraction enriched in histone) but did not produce a substantial effect on cytosolic NFAT (a much larger pool in a cell fraction in which actin is abundant) (Fig.…”

“…thereby allows its translocation to the nucleus (Scott et al, 1997). A contribution of TRPC6 channels to this pathway was initially established in cardiac cells, where it is thought to play a role in angiotensin-mediated cardiac hypertrophy (Kuwahara et al, 2006).…”

Vascular targets of redox signalling in diabetes mellitus

“…Thereby, the impact of Ca 2+ on gene expression exceeded its role in the nuclear envelope, where Ca 2+ is essential for modulating immediate early genes by modulating the DNA-binding of transcription factors (e. g. cAMP-responsive element binding protein CREB [191,192,198,199,200]). Ca 2+ triggers the activation of transcription factors such as the nuclear factor of activated T cells (NFAT) [201,202,203,204,205,206] and the serum response factor-related proteins (RSRF or the myocyte enhancer factor 2 (MEF2) [207]) by calcineurin [208] or Ca 2+ -sensitive kinases (e. g. Cam-kinase IV [207]). In the case of NFAT, the Ca 2+ /calmodulin-activated protein phosphatase-2B (calcineurin) dephosphorylates NFAT resulting in its translocation into the nucleus [208] to form a heteromeric transcriptional activator complex with activator-protein-1 (AP-1) and initiates gene expression [202].…”

“…Ca 2+ triggers the activation of transcription factors such as the nuclear factor of activated T cells (NFAT) [201,202,203,204,205,206] and the serum response factor-related proteins (RSRF or the myocyte enhancer factor 2 (MEF2) [207]) by calcineurin [208] or Ca 2+ -sensitive kinases (e. g. Cam-kinase IV [207]). In the case of NFAT, the Ca 2+ /calmodulin-activated protein phosphatase-2B (calcineurin) dephosphorylates NFAT resulting in its translocation into the nucleus [208] to form a heteromeric transcriptional activator complex with activator-protein-1 (AP-1) and initiates gene expression [202]. In vascular smooth muscle cells NFAT activation by increasing cytosolic free Ca 2+ concentration depends on the patterns of the Ca 2+ signalling observed in response to the compound tested.…”