scholarly journals A Conserved p38 Mitogen-Activated Protein Kinase Pathway Regulates Drosophila Immunity Gene Expression

1998 ◽  
Vol 18 (6) ◽  
pp. 3527-3539 ◽  
Author(s):  
Zhiqiang Stanley Han ◽  
Hervé Enslen ◽  
Xiaodi Hu ◽  
Xiangjun Meng ◽  
I-Huan Wu ◽  
...  

ABSTRACT Accumulating evidence suggests that the insect and mammalian innate immune response is mediated by homologous regulatory components. Proinflammatory cytokines and bacterial lipopolysaccharide stimulate mammalian immunity by activating transcription factors such as NF-κB and AP-1. One of the responses evoked by these stimuli is the initiation of a kinase cascade that leads to the phosphorylation of p38 mitogen-activated protein (MAP) kinase on Thr and Tyr within the motif Thr-Gly-Tyr, which is located within subdomain VIII. We have investigated the possible involvement of the p38 MAP kinase pathway in the Drosophila immune response. Two genes that are highly homologous to the mammalian p38 MAP kinase were molecularly cloned and characterized. Furthermore, genes that encode two novelDrosophila MAP kinase kinases, D-MKK3 and D-MKK4, were identified. D-MKK3 is an efficient activator of bothDrosophila p38 MAP kinases, while D-MKK4 is an activator of D-JNK but not D-p38. These data establish that Drosophilaindeed possesses a conserved p38 MAP kinase signaling pathway. We have examined the role of the D-p38 MAP kinases in the regulation of insect immunity. The results revealed that one of the functions of D-p38 is to attenuate antimicrobial peptide gene expression following exposure to lipopolysaccharide.

2000 ◽  
Vol 279 (5) ◽  
pp. F954-F959 ◽  
Author(s):  
Yoshihisa Ishikawa ◽  
Tsuneo Konta ◽  
Masanori Kitamura

To understand how isolation and explantation of glomeruli affect the function of resident cells, the present study investigated the transcriptional profile of explanted normal glomeruli. We found that ex vivo incubation of glomeruli spontaneously expressed monocyte chemoattractant protein-1 (MCP-1) and stromelysin, the genes regulated by activator protein-1 (AP-1). The expression was suppressed by heparin and quercetin, the drugs with anti-AP-1 activities. The gene expression was preceded by 1) induction of AP-1 components c- fos and c- jun and 2) phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein (MAP) kinase, and c-Jun NH2-terminal kinase (JNK), the upstream inducers/activators of AP-1. Suppression of ERK by PD098059 abrogated induction of c- fos and c- jun, and the p38 MAP kinase inhibitor SB203580 attenuated c- fos expression. Furthermore, treatment with either PD098059, SB203580, or the JNK-AP-1 inhibitor curcumin diminished the expression of MCP-1 and stromelysin. The transcriptional profile of glomerular cells thus alters dramatically after explantation of glomeruli. It is, at least in part, due to activation of multiple MAP kinases that lead to induction of AP-1-dependent gene expression.


2003 ◽  
Vol 23 (1) ◽  
pp. 370-381 ◽  
Author(s):  
Concetta Ambrosino ◽  
Gaetane Mace ◽  
Stefanie Galban ◽  
Cornelius Fritsch ◽  
Kristina Vintersten ◽  
...  

ABSTRACT p38 mitogen-activated protein (MAP) kinases play an important role in the regulation of cellular responses to all kinds of stresses. The most abundant and broadly expressed p38 MAP kinase is p38α, which can also control the proliferation, differentiation, and survival of several cell types. Here we show that the absence of p38α correlates with the up-regulation of one of its upstream activators, the MAP kinase kinase MKK6, in p38α−/− knockout mice and in cultured cells derived from them. In contrast, the expression levels of the p38 activators MKK3 and MKK4 are not affected in p38α-deficient cells. The increase in MKK6 protein concentration correlates with increased amounts of MKK6 mRNA in the p38α−/− cells. Pharmacological inhibition of p38α also up-regulates MKK6 mRNA levels in HEK293 cells. Conversely, reintroduction of p38α into p38α−/− cells reduces the levels of MKK6 protein and mRNA to the normal levels found in wild-type cells. Moreover, we show that the MKK6 mRNA is more stable in p38α−/− cells and that the 3′untranslated region of this mRNA can differentially regulate the stability of the lacZ reporter gene in a p38α-dependent manner. Our data indicate that p38α can negatively regulate the stability of the MKK6 mRNA and thus control the steady-state concentration of one of its upstream activators.


2000 ◽  
Vol 191 (2) ◽  
pp. 321-334 ◽  
Author(s):  
Nicole L. Diehl ◽  
Hervé Enslen ◽  
Karen A. Fortner ◽  
Chris Merritt ◽  
Nate Stetson ◽  
...  

The development of T cells in the thymus is coordinated by cell-specific gene expression programs that involve multiple transcription factors and signaling pathways. Here, we show that the p38 mitogen-activated protein (MAP) kinase signaling pathway is strictly regulated during the differentiation of CD4−CD8− thymocytes. Persistent activation of p38 MAP kinase blocks fetal thymocyte development at the CD25+CD44− stage in vivo, and results in the lack of T cells in the peripheral immune system of adult mice. Inactivation of p38 MAP kinase is required for further differentiation of these cells into CD4+CD8+ thymocytes. The arrest of cell cycle in mitosis is partially responsible for the blockade of differentiation. Therefore, the p38 MAP kinase pathway is a critical regulatory element of differentiation and proliferation during the early stages of in vivo thymocyte development.


1996 ◽  
Vol 16 (3) ◽  
pp. 1247-1255 ◽  
Author(s):  
J Raingeaud ◽  
A J Whitmarsh ◽  
T Barrett ◽  
B Dérijard ◽  
R J Davis

The p38 mitogen-activated protein (MAP) kinase signal transduction pathway is activated by proinflammatory cytokines and environmental stress. The detection of p38 MAP kinase in the nucleus of activated cells suggests that p38 MAP kinase can mediate signaling to the nucleus. To test this hypothesis, we constructed expression vectors for activated MKK3 and MKK6, two MAP kinase kinases that phosphorylate and activate p38 MAP kinase. Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. Cotransfection experiments demonstrated that p38 MAP kinase activation causes increased reporter gene expression mediated by the transcription factors ATF2 and Elk-1. These data demonstrate that the nucleus is one target of the p38 MAP kinase signal transduction pathway.


2002 ◽  
Vol 87 (05) ◽  
pp. 888-898 ◽  
Author(s):  
Stefania Gaino ◽  
Valeria Zuliani ◽  
Rosa Tommasoli ◽  
Donatella Benati ◽  
Riccardo Ortolani ◽  
...  

SummaryWe investigated similarities in the signaling pathways elicited by the F2 isoprostane 8-iso-PGF2α and by low doses of U46619 to induce platelet activation. Both 0.01-0.1 µmol/L U46619 and 0.01-1 µmol/L 8-isoPGF2α triggered shape change and filopodia extension, as well as adhesion to immobilized fibrinogen of washed platelets. At these doses the two platelet agonists failed to trigger secretion and aggregation, which were however induced by higher doses of U46619 (0.1-1 µmol/L). SB203580 (1-10 µmol/L), a specific inhibitor of the p38 mitogen activated protein (MAP) kinase blunted platelet shape change and adhesion induced by 0.05-1 µmol/L 8-iso-PGF2α and by 0.01 µmol/L U46619. These platelet responses were also inhibited by 20 µmol/L cytochalasin D, an inhibitor of actin polymerization, and 50 µmol/L piceatannol, an inhibitor of the Syk tyrosine kinases. Both 8-iso-PGF2α and U46619-induced p38 MAP kinase phosphorylation in suspended platelets and this was inhibited by piceatannol, indicating that Syk activation occurs upstream p38 MAP kinase phosphorylation. These findings suggest that the signaling pathway triggered by both 8-iso-PGF2α and low concentrations of U46619 to induce platelet adhesion and shape change implicates Syk, the p38 MAP kinase, and actin polymerization.


Endocrinology ◽  
1997 ◽  
Vol 138 (8) ◽  
pp. 3103-3111 ◽  
Author(s):  
Masahide Ohmichi ◽  
Koji Koike ◽  
Akiko Kimura ◽  
Kanji Masuhara ◽  
Hiromasa Ikegami ◽  
...  

Abstract In this study, prostaglandin (PG) F2α was found to activate mitogen-activated protein (MAP) kinase and MAP kinase kinase (MEK) in cultured rat puerperal uterine myometrial cells. PGF2α stimulation also led to an increase in phosphorylation of raf-1, son of sevenless (SOS), and Shc. Furthermore, we examined the mechanism by which PGF2α induced MAP kinase phosphorylation. Both pertussis toxin (10 ng/ml), which inactivates Gi/Go proteins, and expression of a peptide derived from the carboxyl terminus of the β-adrenergic receptor kinase 1 (βARK1), which specifically blocks signaling mediated by the βγ subunits of G proteins, blocked the PGF2α-induced activation of MAP kinase. Ritodrine (1 μm), which is known to relax uterine muscle contraction, attenuated PGF2α-induced tyrosine phosphorylation of MAP kinase. Moreover, to examine the role of MAP kinase pathway in uterine contraction, an inhibitor of MEK activity, PD098059, was used. Although MEK inhibitor had no effect on PGF2α-induced calcium mobilization, this inhibitor partially inhibited PGF2α-induced uterine contraction. These results provide evidence that PGF2α stimulates the MAP kinase signaling pathway in cultured rat puerperal uterine myometrial cells through Gβγ protein, suggesting that this new pathway may play an important role in the biological action of PGF2α on these cells.


2002 ◽  
Vol 22 (12) ◽  
pp. 4073-4085 ◽  
Author(s):  
Rachel J. Buchsbaum ◽  
Beth A. Connolly ◽  
Larry A. Feig

ABSTRACT Tiam1 and Ras-GRF1 are guanine nucleotide exchange factors (GEFs) that activate the Rac GTPase. The two GEFs have similar N-terminal regions containing pleckstrin homology domains followed by coiled-coils and additional sequences that function together to allow regulated GEF activity. Here we show that this N-terminal region of both proteins binds to the scaffold protein IB2/JIP2. IB2/JIP2 is a scaffold for the p38 mitogen-activated protein (MAP) kinase cascade because it binds to the Rac target MLK3, the MAP kinase kinase MKK3, and the p38 MAP kinase. Expression of IB2/JIP2 in cells potentiates the ability of Tiam1 or Ras-GRF1 to activate the p38 MAP kinase cascade but not the Jnk MAP kinase cascade. In addition, Tiam1 or Ras-GRF1 binding to IB2/JIP2 increases the association of the components of the p38 MAP kinase signaling cassette with IB2/JIP2 in cells and activates scaffold-associated p38. These findings imply that Tiam1 and Ras-GRF1 can contribute to Rac signaling specificity by their ability to form a complex with a scaffold that binds components of one of the many known Rac effector pathways.


Sign in / Sign up

Export Citation Format

Share Document