Essential role of calcium in the regulation of MAP kinase phosphatase-1 expression

Transcriptional elongation of many eukaryotic, prokaryotic, and viral genes is tightly controlled, which contributes to gene regulation. Here we describe this phenomenon for the MAP kinase phosphatase 1 (MKP-1) immediate early gene. In rat GH4C1 pituitary cells, MKP-1 mRNA is rapidly and transiently induced by the thyrotropin-releasing hormone (TRH) and the epidermal growth factor EGF via transcriptional activation of the gene. Ca 2؉ signals are necessary for the induction of MKP-1 in response to TRH but not to EGF. Reporter gene analysis with the newly cloned rat promoter sequence shows only limited induction in response to various stimuli, including TRH or EGF. By nuclear run-on assays we demonstrate that in basal conditions, a strong block to elongation in the first exon regulates the MKP-1 gene and that stimulation with either TRH or EGF overcomes the block. Ca 2؉ signals are important to release the MKP-1 elongation block in a manner similar to the c-fos oncogene. These results suggest that a common mechanism of intragenic regulation may be conserved between MKP-1 and c-fos in mammalian cells.Long term cellular processes such as proliferation, differentiation, and neuronal plasticity are controlled by extracellular stimuli and require the synthesis of new gene products. Following stimulation, expression of immediate early genes (IEGs) precedes the expression of late response genes, the latter encoding for proteins implicated in specific functions. The best known IEG products are transcription factors such as c-Fos, c-Jun, and c-Myc, which control the expression of late response genes (1, 2). Not all IEGs encode for transcription factors. For instance, structural proteins like actin or tropomyosin, cytokines, and other regulatory proteins show a rapid and transient induction by growth factors (1).Recently, a group of dual specificity phosphatases have been identified as being IEG products induced by various stimuli (growth factors, stress, neurotransmittors, etc.; reviewed in Ref.3). These dual specificity (threonine/tyrosine) phosphatases have been named MAP kinase phosphatases (DSPs or MKPs), since they are effective in the inactivation of MAP kinases by dual dephosphorylation (4). MAP kinase phosphatase-1 (MKP-1/CL100/3CH134) is one example of this group of nuclear enzymes encoded by an IEG. Although MKP-1 gene transcription is activated by multiple signals, such as mitogens (5, 6), cytokines (7), oxidative stress (8), heat shock (8), or hypoxia (9), the precise mode of gene regulation of this immediate early gene by such stimuli remains unclear. A comparison of the 5Ј-flanking sequence of the murine and the human genes revealed two conserved Ca 2ϩ /cAMP-responsive elements (CREs) and one E box motif in the promoter region of MKP-1. Recently, the upstream stimulatory factor, a member of the basic/helix-loop-helix/leucine zipper family has been shown to bind to the E box motif and transactivate MKP-1 expression in synergy with protein kinase A (10). Since multiple intracellular signals can target MKP-1 gen...

Section: Rapid Induction Of Mkp-1 Mrna By Trh and Egf In Pituitary Ghmentioning

confidence: 59%

Section: -41mentioning

confidence: 99%

MAP Kinase Phosphatase-1 Gene Transcription in Rat Neuroendocrine Cells Is Modulated by a Calcium-sensitive Block to Elongation in the First Exon

Ryser¹,

Tórtola²,

Haasteren³

et al. 2001

“…Given the fact that a particular stimulus can trigger various signaling cascades depending on the cell type, different kinases are expected to be involved in the export and transcriptional deactivation of NFAT in distinct cell types. For example, calcium elevation induced by ionophores activates only very weakly, or not at all, the p38 MAPK pathway in fibroblasts (51), whereas the same stimulus triggers a strong and sustained activation of p38 MAPK in PBLs (Fig. 1B).…”

Section: Discussionmentioning

confidence: 99%

A Role for the p38 MAP Kinase Pathway in the Nuclear Shuttling of NFATp

Arco¹,

Martı́nez-Martı́nez²,

Maldonado³

et al. 2000

142

Calcium signals lead to the translocation of nuclear factor of activated T cells (NFAT) from the cytoplasm to the nucleus. This process is regulated by the calciumactivated phosphatase calcineurin, which can be cotransported with NFAT to the nucleus to maintain it transcriptionally active for the duration of calcium signaling. When the calcium signal ceases, NFAT is exported to the cytoplasm, and different NFAT kinases have been reported to oppose calcineurin activities and regulate the nuclear export of NFAT. Here we show that p38 MAPK phosphorylates in vitro and interacts in vivo with NFATp. Furthermore, the activation of this pathway in HeLa cells by cotransfection with activated MKK6 and p38 counteracts the calcium-induced nuclear accumulation of NFATp but not that of NFATc. By contrast, activation of JNK or ERK pathways failed to modify the nuclear shuttling of NFATp. Consistently, activation of p38, but not the JNK MAPK pathway, results in the inhibition of NFATp-driven transcription. In addition, the inhibition of the nuclear accumulation of NFATp by p38 appears to be mediated through the activation of NFATp nuclear export and takes place in a Leptomycin B-sensitive fashion, suggesting the involvement of the exportin CRM1 in this process. Thus, the p38 signal transduction pathway appears to play an important role in the regulation of the nuclear shuttling of NFATp and in cellular homeostasis.

“…Changes in [Ca 2ϩ ] i in skeletal muscle cells often involve a signaling pathway dependent on calcineurin, a Ca 2ϩ -calmodulin-regulated serine/threonine phosphatase (7,51). In addition, an increase in [Ca 2ϩ ] i by Ca 2ϩ -ionophore A23187 has been shown to induce MKP-1 mRNA and protein in rat fibroblasts (52). MKPs are a family of dual specificity protein phosphatases with MKP-1 preferentially inactivating p38 MAPK and c-Jun N-terminal kinase at least in some cell lines (53).…”

Section: Journal Of Biological Chemistry 7271mentioning

confidence: 99%

The p38α/β Mitogen-activated Protein Kinases Mediate Recruitment of CREB-binding Protein to Preserve Fast Myosin Heavy Chain IId/x Gene Activity in Myotubes

Meißner¹,

Chang

Kubis³

et al. 2007

In skeletal muscle, the transformation of fast into slow fiber type is accompanied by shifts in fiber type-specific gene expression that includes down-regulation of the adult fast fiber myosin heavy chain IId/x (MyHCIId/x) gene. Here, we report that the mitogen-activated protein kinases (MAPKs) p38␣/␤ regulate MyHCIId/x gene expression. Electrical stimulation of rabbit skeletal muscle cells with a slow fiber type activity pattern and treatment of C2C12 myotubes with Ca 2؉ -ionophore inhibited p38␣/␤ MAPKs and reduced fast fiber type MyHC protein expression and promoter activity. Pharmacological inhibition of p38␣/␤ also down-regulated MyHCII gene expression. In controls, binding of the myocyte enhancer factor-2 (MEF-2) isoforms C and D as a heterodimer to a proximal consensus site within the MyHCIId/x promoter and recruitment of a transcriptional coactivator, the CREB-binding protein CBP, were observed. Overexpression of wild type MEF-2C but not of a MEF-2C mutant that cannot be phosphorylated by p38 induced promoter activity. Mutation of the MEF-2-binding site decreased the inducing effect of overexpressed CBP. Inhibition of p38␣/␤ MAPKs abolished CBP binding, whereas enforced induction of p38 by activated MAPK kinase 6 (MKK6EE) enhanced binding of CBP and increased promoter activity. Furthermore, knockdown of endogenous CBP by RNA interference eliminated promoter activation by MEF-2C or MKK6EE. In electrical stimulated and Ca 2؉ -ionophore-treated myotubes, CBP was absent in complex formation at that site. Taken together, the data indicate that p38␣/␤ MAPKs-mediated coactivator recruitment at a proximal MEF-2 site is important for MyHCIId/x gene regulation in skeletal muscle.Skeletal muscle fibers have been classified into fiber types based on their contraction speed, force development, fatigability, and metabolic functions (1). The characteristic fiber types are fast twitch glycolytic (type IID/X and IIB), fast twitch oxidative/glycolytic (type IIA), and slow twitch oxidative (type I/␤). Fast fibers express the IID/X, IIB, or IIA isoform of the myosin heavy chain (MyHC), 3 whereas slow fibers predominantly express the type I/␤ isoform. The functional, biochemical, and morphological differences between fiber types are a consequence of different fiber-specific gene expression patterns. Fibers are characterized by a remarkable plasticity and can be modulated by chronic low frequency electrical stimulation depending on the imposed activity pattern (2). Physiologically, this transformation process in fiber type occurs in response to altered demands, such as increases in muscle activity (3). Fiber type shifts are also observed during aging and disease. The importance of changes in intracellular Ca 2ϩ as a trigger for fiber type transformation has clearly been demonstrated by a Ca 2ϩ -ionophore-induced fast-to-slow transformation in primary skeletal muscle cells (4, 5). The involvement of calcineurin, a Ca 2ϩ -calmodulin-regulated serine/threonine phosphatase, in transducing the Ca 2ϩ -signal into altered gene expre...