Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.2 (PDK1)
 2,238 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracellular nucleotides can activate a common purinoceptor mediating various cell responses. In this study we report that stimulation of rat mesangial cells with ATP and UTP leads to a rapid activation of the protein kinase B/Akt (PKB) pathway. Time-course studies reveal a rapid and transient phosphorylation of both Ser(473) and Thr(308) of PKB with a maximal effect after 5 min of stimulation. The response is concentration-dependent with a maximal effect at 30 microM of ATP and UTP. Western blot analysis of mesangial cells reveals the expression of the isoenzymes PKB-alpha and PKB-gamma, but not the PKB-beta. ATP and UTP also activate the upstream located PI 3-kinase-dependent kinase. Furthermore, the ATP- and UTP-induced PKB phosphorylation is abolished by two inhibitors of the PI 3-kinase. In addition, suramin, a putative P2Y(2) receptor antagonist, and pertussis toxin, an inhibitor of G(i)/G(o) activation, markedly block ATP- and UTP-induced PKB phosphorylation. A series of ATP and UTP analogues were tested for their ability to stimulate PKB phosphorylation. UTP, ATP and gamma-thio-ATP are the only compounds capable of activating PKB. Stress-induced apoptosis of mesangial cells is reduced by the stable ATP analogue, gamma-thio-ATP, and this inhibitory effect is reversed in the presence of LY 294002. In summary, these results demonstrate that extracellular nucleotides are able to activate the PI 3-kinase/PDK/PKB cascade via the P2Y(2)-receptor and a pertussis toxin-sensitive G(i) protein. Moreover, in mesangial cells this cascade may have an important role in the antiapoptotic response but not in the mitogenic or inflammatory response produced by extracellular nucleotides.
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PMID:Extracellular ATP and UTP activate the protein kinase B/Akt cascade via the P2Y(2) purinoceptor in renal mesangial cells. 1205 30

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used as analgesics. They inhibit cyclooxygenases (COX), preventing the formation of prostaglandins, including prostacyclin and thromboxane. A serious side effect of COX-1 and COX-2 inhibitors is renal damage. To investigate the molecular basis of the renal injury, we evaluated the expression of the stress marker, heme oxygenase-1 (HO-1), in celecoxib-stimulated mesangial cells. We report here that a COX-2 selective NSAID, celecoxib, induced a concentration- and time-dependent increase of HO-1 expression in glomerular mesangial cells. Celecoxib-induced HO-1 protein expression was inhibited by actinomycin D and cycloheximide, suggesting that de novo transcription and translation are required in this process. N-acetylcysteine, a free radical scavenger, strongly decreased HO-1 expression, suggesting the involvement of reactive oxygen species (ROS). Celecoxib-induced HO-1 expression was attenuated by pretreatment of the cells with SP 600125 (a specific JNK inhibitor), but not SB 203580 (a specific p38 MAPK inhibitor), or PD 98059 (a specific MEK inhibitor). Consistently, celecoxib activated c-Jun N-terminal kinase (JNK) as demonstrated by kinase assays and by increasing phosphorylation of this kinase. N-acetylcysteine reduced the stimulatory effect of celecoxib on stress kinase activities, suggesting an involvement of JNK in HO-1 expression. On the other hand, LY 294002, a phosphatidylinositol 3-kinase (PI-3K)-specific inhibitor, prevented the enhancement of HO-1 expression. This effect was correlated with inhibition of the phosphorylation of the PDK-1 downstream substrate Akt/protein kinase B (PKB). In conclusion, our data suggest that celecoxib-induced HO-1 expression in glomerular mesangial cells may be mediated by ROS via the JNK-PI-3K cascade.
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PMID:Celecoxib induces heme-oxygenase expression in glomerular mesangial cells. 1596 68

Homo- and heterodimers of platelet-derived growth factor-A (PDGF-A) and PDGF-B chains are involved through PDGF alpha- and beta-receptors in the growth regulation of multiple normal and tumoural cell types as well as in tumour neovascularization. Since little information is available on the impact of PDGF/PDGF receptors in normal and adenomatous pituitary, we studied the expression and action of this growth factor system in a variety of pituitary tumour cell lines and in rat anterior pituitary cell cultures. By RT-PCR, mRNA expression of PDGF-A and -B chains and of both receptors was found in rat pituitary and mouse folliculostellate TtT/GF pituitary tumour cells. Rat somatotroph MtT-S and mouse corticotroph AtT20 tumor cells expressed only a part of the PDGF/PDGF receptor components whereas mouse gonadotroph alphaT3-1 and rat lactosomatotroph GH3 pituitary tumour cells contained neither PDGF nor PDGF receptors. To further characterize the role of PDGF in TtT/GF cells, the effect of PDGF-AB and -BB on growth and vascular endothelial growth factor-A (VEGF-A) release was studied. Proliferation of TtT/GF cells was weakly but significantly stimulated by PDGF. Both in rat pituitary cell cultures and in TtT/GF cells, PDGF-AB and -BB strongly enhanced VEGF-A secretion. The PI3 kinase inhibitor LY 294002 blocked the increase in VEGF-A. Western immunoblotting confirmed the participation of key components of the PI3 kinase/Akt signal pathway (PDK1, Akt-Ser476) in PDGF-stimulated VEGF production. Thus the PDGF/PDGF receptor system is expressed in folliculostellate cells and is involved in VEGF regulation. Its role in endocrine pituitary tumour cell lines and pituitary adenomas need to be clarified in future studies.
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PMID:Platelet-derived growth factor (PDGF) and PDGF receptor expression and function in folliculostellate pituitary cells. 1937 54