Nur77 protein has also been shown to be a phospho-protein in cells, suggesting that its activity may be controlled by protein kinase signalling cascades, a mechanism common to additional nuclear receptors as well as unrelated transcription factors such as FOXOs (forkhead box Os), CREB (cAMP-response-element-binding protein) and Ets factors [18C20]. Nur77 has been reported to be phosphorylated at several sites, including Ser142, Thr145 [21,22] and Ser354 (amino acid figures are for murine Nur77). to 14-3-3 proteins (also referred to as or is definitely expressed in a variety of cell types, and has been implicated in both the rules of genes in the hypothalamicCpituitaryCadrenal axis associated with swelling and steroidogenesis and also in the rules of apoptosis. In T-cells, Nur77 is definitely suggested to promote the apoptosis of immature self-reactive T-cells in the thymus [2C5], while, in additional cell types, Nur77 has been reported to both promote or inhibit apoptosis [6C9]. Nur77, and also Nurr1 and Nor1, are able to bind as monomers to NBREs [NGF (nerve growth element)-induced B element response element) (AAAGGTCA) and as homodimers to NurREs Rabbit polyclonal to HOXA1 (Nur response elements) (TGATATTTX6AAATGCCA) in DNA [10]. At present, no physiological ligand has been explained for Nur77, although recently it has been suggested that 1,1-bis-(3-indolyl)-1-(and genes are immediate early genes, and may become up-regulated in cells via a variety of stimuli, including (-)-Huperzine A NGF, depolarization, (-)-Huperzine A serum, PMA, EGF (epidermal growth element) and anisomycin [15C17]. Nur77 protein has also been demonstrated to be a phospho-protein in cells, suggesting that its activity may be controlled by protein kinase signalling cascades, a mechanism common to additional nuclear receptors as well as unrelated transcription factors (-)-Huperzine A such as FOXOs (forkhead package Os), CREB (cAMP-response-element-binding protein) and Ets factors [18C20]. Nur77 has been reported to be phosphorylated at several sites, including Ser142, Thr145 [21,22] and Ser354 (amino acid figures are for murine Nur77). Ser354 lies in the A package of the DNA-binding website of Nur77, a region of the protein adjacent to the zinc-finger website. The phosphorylation of Ser354 is definitely potentially important in Nur77 rules, as phosphorylation of this site has been suggested to inhibit the DNA binding of Nur77 [23]. Consistent with this, the crystal structure of the Nur77 DNA-binding website has shown that Ser354 forms a hydrogen relationship to the phosphate backbone of the DNA [24]. Based on the crystal structure, the intro of a negative charge by phosphorylation of this residue would be expected to interfere with the binding of the A package to DNA. While there is evidence that phosphorylation of this site can have practical significance in cells, the pathways and kinases which control phosphorylation of this site are less well recognized. In Personal computer12 cells (derived from rat pheochromocytoma) stimulated with NGF or bFGF (fundamental fibroblast growth element) Nur77 was reported to be phosphorylated on multiple sites. PMA or EGF activation was also reported to stimulate the phosphorylation of Nur77, but on fewer sites than NGF or bFGF [25], even though phosphorylated sites were not recognized in these studies. Using phospho-specific antibodies against Ser354, NGF but not membrane depolarization [26] was found to promote phosphorylation of this site in Personal computer12 cells. In NGF-stimulated Personal computer12 cells, the kinase responsible for the phosphorylation of Ser354 of Nur77 was initially described as becoming unique from RSK (ribosomal S6 kinase), but identical with the kinase responsible for the phosphorylation of CREB [23]. The kinases that phosphorylate CREB have since been identified as MSK1 (mitogen- and stress-activated protein kinase 1) and MSK2 [27,28], which are known to be able to phosphorylate related focuses on to RSK [29]. In contrast, other studies possess reported that RSK is able to phosphorylate Nur77 [30,31], and also in cells [32]. These studies made use of biochemical purification and characterization of the Nur77 kinase in order to determine it; however, this can give rise to misleading results as partially purified kinases which phosphorylate a substrate in assays are not constantly the physiological kinases for the substrate. It is therefore necessary to also use other approaches to confirm that the correct kinase has been identified. More recently, PKB (protein kinase B)/Akt has been suggested as the kinase responsible for phosphorylation of Ser354 in Nur77. PKB offers been shown to be able to phosphorylate the DNA-binding website of Nur77 [26]. PKA, however, appears unlikely to phosphorylate Nur77 as providers that elevate cAMP in cells, and therefore activate PKA, have been shown to stimulate DNA binding of Nur77 and promote its dephosphorylation at Ser354 [34,35]. In the.