Expression Of P38 Mitogen-activated Protein Kinase Research Articles

The p38 Mitogen-Activated Protein Kinase Is Involved in Associative Learning in Rabbits

This study examined the role of the mitogen-activated protein kinase (MAPK) family during acquisition of the rabbit's classically conditioned eye-blink response. Eye-blink conditioning produced a significant, bilateral activation of both extracellular signal-regulated protein kinases (ERKs) and p38 MAPK in the anterior cerebellar vermis. There was also a significant bilateral activation of ERKs in the dorsal hippocampus with no change in p38 MAPK. These changes were seen at 2 min after the last conditioning session, were maintained for at least 180 min, and occurred without any change in the protein expression of either ERKs or p38 MAPK. There were no changes in ERKs or p38 MAPK in frontal cortex, in cerebellar hemispheral lobule VI, or in a section of brainstem containing the inferior olive. Moreover, the stress-related protein kinase Jun N-terminal kinase (JNK), another subfamily of MAPKs, was not altered in any of the brain regions examined. Animals receiving explicitly unpaired presentations of a conditioned stimulus and an unconditioned stimulus did not acquire conditioned responses (CRs) and did not demonstrate any changes in ERKs, p38 MAPK, or JNK. The intraventricular injection of SB203580, a selective p38 MAPK inhibitor, significantly retarded CR acquisition and blocked the learning-related increases in p38 MAPK activity in the anterior vermis. PD98059, a selective MAPK kinase inhibitor, had a smaller and only marginally significant effect on CR acquisition, although it did block the learning-related increases in ERK activity in both the hippocampus and anterior vermis. These results indicate that p38 MAPK is activated during associative learning and may play a role in the transcriptional events that lead to memory consolidation.

Exercise-associated differences in an array of proteins involved in signal transduction and glucose transport.

Vastus lateralis muscle biopsies were obtained from endurance-trained (running approximately 50 km/wk) and untrained (no regular physical exercise) men, and the expression of an array of insulin-signaling intermediates was determined. Expression of insulin receptor and insulin receptor substrate-1 and -2 was decreased 44% (P < 0.05), 57% (P < 0.001), and 77% (P < 0.001), respectively, in trained vs. untrained muscle. The downstream signaling target, Akt kinase, was not altered in trained subjects. Components of the mitogenic signaling cascade were also assessed. Extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase expression was 190% greater (P < 0.05), whereas p38 mitogen-activated protein kinase expression was 32% lower (P < 0.05), in trained vs. untrained muscle. GLUT-4 protein expression was twofold higher (P < 0.05), and the GLUT-4 vesicle-associated protein, the insulin-regulated aminopeptidase, was increased 4.7-fold (P < 0. 05) in trained muscle. In conclusion, the expression of proteins involved in signal transduction is altered in skeletal muscle from well-trained athletes. Downregulation of early components of the insulin-signaling cascade may occur in response to increased insulin sensitivity associated with endurance training.

The p38 Mitogen-activated Protein Kinase Is Required for NF-κB-dependent Gene Expression: THE ROLE OF TATA-BINDING PROTEIN (TBP)

Endotoxin-induced cytokine gene transcription in monocytes and macrophages is regulated in part by NF-kappaB. We have previously shown that the p38 mitogen-activated protein (MAP) kinase is necessary for endotoxin-induced cytokine gene transcription. Due to the fact that most cytokine promoter sequences have active NF-kappaB sites, we hypothesized that the p38 MAP kinase was necessary for NF-kappaB-dependent gene expression. We found that NF-kappaB-dependent gene expression was reduced to near control levels with either SB 203580 or a dominant-negative p38 MAP kinase expression vector. Inhibition of the p38 MAP kinase did not alter NF-kappaB activation at any level, but it significantly reduced the DNA binding of TATA-binding protein (TBP) to the TATA box. The dominant-negative p38 MAP kinase expression vector interfered with the direct interaction of native TFIID (TBP) with a co-transfected p65 fusion protein. Likewise, this dominant-negative plasmid also interfered with the direct interaction of a co-transfected TBP fusion protein with the native p65 subunit. The p38 kinase also phosphorylated TFIID (TBP) in vitro, and SB 203580 inhibited phosphorylation of TFIID (TBP) in vivo. Thus, the p38 MAP kinase regulates NF-kappaB-dependent gene transcription, in part, by modulating activation of TFIID (TBP).

P38 Map Kinase Is Expressed in the Pancreas and Is Immediately Activated following Cerulein Hyperstimulation

Background: The pathophysiology of pancreatitis and the pancreatic stress response are not well understood. In the pancreas, mitogen-activated protein kinase (MAPK) and stress-activated protein kinase (SAPK) are reportedly regulated by secretagogue stimulation and hyperstimulation. However, no data exist on the expression and regulation of pancreatic p38 Map kinase. Aims: Pancreatic expression of p38 Map kinase and MAPK, SAPK and p38 regulation during pancreatic stress were investigated. Methods: For hyperstimulation and secretory stress, cerulein was given intravenously, while hyperthermia preconditioning stress was induced by whole body hyperthermia (42°C). Results: In addition to MAPK and SAPK, p38 Map kinase was found to be expressed in the rat pancreas. Cerulein regulated all kinases time- and dose-dependently. MAPK and p38 Map kinase showed basal activity and were further activated at low cerulein doses. SAPK had no basal activity and its activation required maximal secretory to supramaximal amounts of cerulein. Cerulein hyperstimulation, inducing pancreatitis, activated p38 more rapidly than SAPK and more strongly than MAPK. In contrast to cerulein hyperstimulation stress, hyperthermia stress only activated p38 Map kinase. Conclusions: p38 Map kinase is expressed in the pancreas and is most rapidly activated following cerulein hyperstimulation. Both SAPK and p38 Map kinase are possibly important regulators during the onset of cerulein pancreatitis.

P38 mitogen-activated protein kinase expression and activation in smooth muscle.

There is relatively little known about expression and activation of p38 mitogen-activated protein kinases (MAPKs) through G protein-linked, seven-transmembrane-spanning (STM) receptors in mammalian smooth muscle. To investigate the role of p38 MAPK in smooth muscle, we cloned and sequenced the p38 MAPK expressed in canine smooth muscles. A full-length clone of the canine p38 MAPK expressed in colonic smooth muscle was obtained by RT-PCR. The deduced amino acid sequence revealed 99% identity to the human p38 MAPK and differed from the human enzyme in only two conservative substitutions. The deduced molecular mass of the canine p38 MAPK is 41.2 kDa, with a calculated isoelectric point of 5.41. Canine p38 MAPK was found to be expressed in colonic, tracheal, and vascular smooth muscles and underwent increased tyrosine phosphorylation in response to motor neurotransmitters, acetylcholine (ACh) and neurokinin A (NKA), in colonic smooth muscle. There was an eightfold increase in p38 MAPK phosphorylation after a 10-min incubation with ACh and a threefold increase with NKA. We also identified a p38 immunoreactive kinase activity isolated from colonic smooth muscle homogenate by Mono Q chromatography. Partially purified p38 MAPK and activated recombinant p38 MAPK (Mpk2) phosphorylated both the known p38 MAPK substrate ATF2, as well as porcine stomach h-caldesmon in vitro. The results suggest that elements of the "stress-response" pathway may be coupled to transcriptional control as well as to cytoskeletal and possibly contractile protein phosphorylation in mammalian smooth muscle.

The Critical Role of p38 MAP Kinase in T Cell HIV-1 Replication

Replication of HIV-1 in human T lymphocytes requires the activation of host cellular proteins. This study identifies p38 mitogen-activated protein kinase (MAPK) as one such kinase necessary for HIV-1 replication in T cells. Primary human T lymphocytes were infected with the LAI strain of HIV-1 and Jurkat cells were infected with the RF strain of HIV-1. HIV replication was measured by reverse transcriptase activity. Cellular expression of endogenous p38 MAPK protein was analyzed using immunoprecipitation. Blockade of p38 MAPK expression was achieved using antisense oligonucleotides to p38 MAPK and the guanylhydrazone compound CNI-1493, an inhibitor of p38 MAPK activation. HIV-1 infection of both primary human T lymphocytes and a T cell line rapidly activated the cellular p38 MAPK pathway, which remained activated for the duration of the culture. Addition of phosphothioated antisense oligonucleotides to p38 MAPK specifically inhibited viral replication. Blockade of p38 MAPK activation by addition of CNI-1493 also inhibited HIV-1 viral replication of primary T lymphocytes in a dose- and time-dependent manner. Stimulation of p38 MAPK activation did not occur with the addition of heat-inactivated virus, suggesting that viral internalization, and not just membrane binding, is necessary for p38 MAPK activation. These results indicate that activation of the p38 MAPK cascade is critical for HIV-1 replication in primary T lymphocytes, and that blockade of this signal transduction pathway may be a novel therapeutic approach to the treatment of HIV-1 infection.