interacts_with DB06616?
Regulation of Na+/H+ exchanger P48764 by glucagon-like peptide 1 receptor agonist exendin-4 in renal proximal tubule cells . The gut incretin hormone glucagon-like peptide 1 ( P0C6A0 ) is released in response to ingested nutrients and enhances insulin secretion . In addition to its insulinotropic properties , P0C6A0 has been shown to have natriuretic actions paralleled by a diminished proton secretion . We therefore studied the role of the P43220 agonist exendin-4 in modulating the activity of Na(+)/H(+) exchanger P48764 in LLC-PK(1) cells . We found that P48764 -mediated Na(+)-dependent intracellular pH ( pH(i) ) recovery decreased approximately 50 % after 30-min treatment with 1 nM exendin-4 . Pharmacological inhibitors and DB02527 analogs that selectively activate protein kinase A ( PKA ) or the exchange protein directly activated by DB02527 ( O95398 ) demonstrated that regulation of P48764 activity by exendin-4 requires activation of both DB02527 downstream effectors . This conclusion was based on the following observations : 1 ) the PKA antagonist H-89 completely prevented the effect of the PKA activator but only partially blocked the exendin-4-induced P48764 inhibition ; 2 ) the Q02750 /2 inhibitor U-0126 abolished the effect of the O95398 activator but only diminished the exendin-4-induced P48764 inhibition ; 3 ) combination of H-89 and U-0126 fully prevented the effect of exendin-4 on P48764 ; 4 ) no additive effect in the inhibition of P48764 activity was observed when exendin-4 , PKA , and O95398 activators were used together . Mechanistically , the inhibitory effect of exendin-4 on pH(i) recovery was associated with an increase of P48764 phosphorylation . Conversely , this inhibition took place without changes in the surface expression of the transporter . We conclude that P43220 agonists modulate sodium homeostasis in the kidney , most likely by affecting P48764 activity . Imatinib mesylate ( Gleevec ) enhances mature osteoclast apoptosis and suppresses osteoclast bone resorbing activity . Recent studies have reported that imatinib mesylate , a kinase inhibitor that targets the intracellular tyrosine kinase P11274 - P00519 and the platelet derived growth factor ( PDGF ) receptor , is an effective inhibitor of the macrophage colony stimulating factor ( P09603 ) receptor , c- P07333 . Given that P09603 signalling through c- P07333 plays an important role in osteoclast biology , we speculated that blocking such a pathway with imatinib may modulate osteoclast activity . Using a cell model of mature rabbit osteoclasts , we thus investigated the effect of imatinib on in vitro osteoclast apoptosis and bone resorbing activity . Our findings demonstrate that imatinib dose-dependently stimulates osteoclast apoptosis , a phenomenon which is blocked by the caspase I inhibitor Z-VAD-fmk . The ability of imatinib to enhance osteoclast cell death was accompanied by a dose-dependent inhibition of osteoclast bone resorbing activity . Imatinib was also found to inhibit P09603 -induced osteoclast survival as well as P09603 -induced osteoclast bone resorbing activity , but was without effect on interleukin 1alpha ( IL-1alpha ) and receptor activator of nuclear factor kappa B ligand ( O14788 ) -induced inhibition of osteoclasts apoptosis , further supporting the hypothesis that imatinib may affect mature osteoclasts through the inhibition of c- P07333 . Taken together , these results suggest that imatinib could be of clinical value in treating diseases where bone destruction can occur due to excessive P09603 production such as osteoporosis , inflammatory-and tumor-induced osteolysis . Novel MEK inhibitor trametinib and other retinoblastoma gene ( RB ) -reactivating agents enhance efficacy of 5-fluorouracil on human colon cancer cells . Chemotherapy for colorectal cancer has become more complicated and diversified with the appearance of molecular-targeting agents . DB00544 ( DB00544 ) has been a mainstay of chemotherapy for colorectal cancer , but it is still unknown whether the combining of DB00544 with novel molecular-targeting agents is effective . P04818 ( TS ) is a direct target of DB00544 , and the low TS level has been generally supposed to sensitize DB00544 's efficacy . We therefore hypothesized that RB-reactivating agents could enhance the efficacy of DB00544 , because the RB-reactivating agents could suppress the function of transcription factor E2F of TS gene promoter . We used three RB-reactivating agents , trametinib/GSK1120212 ( MEK inhibitor ) , fenofibrate ( Q07869 α agonist ) , and LY294002 ( PI3K inhibitor ) , with DB00544 against human colon cancer HT-29 and HCT15 cells . DB08911 induced p15 and p27 expression and reduced cyclin D1 levels in HT-29 cells . Fenofibrate also dephosphorlated P27361 /2 and reduced cyclin D1 levels in HT-29 cells . LY294002 induced p27 expression in HCT15 cells . All three agents caused dephosphorylation of RB protein and P55008 -phase arrest with a reduction of TS expression . As a consequence , the combination of DB00544 with each of the agents resulted in a significant decrease of colony numbers in HT-29 or HCT15 cells . These results suggest " RB-reactivation therapy " using molecular-targeting agents to be a new strategy for DB00544 -based chemotherapy . In particular , we strongly expect trametinib , which was discovered in Japan and was recently submitted to FDA for approval , to be used together with established regimens for colorectal cancer . Evidence of drug-drug interactions through uptake and efflux transport systems in rat hepatocytes : implications for cellular concentrations of competing drugs . For drugs with hepatobiliary transport across hepatocytes , the interplay between uptake and efflux transporters determines hepatic concentrations of drugs , but the evolution over time of these concentrations is difficult to measure in humans other than with magnetic resonance imaging contrast agents in the liver . DB00743 dimeglumine ( BOPTA ) is a contrast agent used in liver magnetic resonance imaging that enters into human hepatocytes through organic anion transporting polypeptides ( P46721 ) and exits unchanged into bile through the multiple resistance-associated protein 2 ( Q92887 ) . DB01045 ( Q9HBH0 ) is transported by the same membrane proteins and may compete with BOPTA for hepatic uptake . Simultaneous drug-drug interactions through uptake and efflux transport systems in hepatocytes according to the cellular concentrations of competing drugs were never investigated . In perfused rat liver preparations , we demonstrate how the drug-drug interactions through transporters determine cellular concentrations of the competing drugs BOPTA and Q9HBH0 , and we show that the cellular concentrations by modulating transport through membranes regulate the rat Oatp-Mrp2 interplay . Moreover , drug interactions through transporters change greatly over time . Differential effects of P43220 agonists on components of dysglycaemia in individuals with type 2 diabetes mellitus . Metabolic consequences of glucagon-like peptide-1 receptor agonists ( P0C6A0 RAs ) are the result of enhanced glucose-stimulated insulin secretion , inhibition of glucagon release , delayed gastric emptying and increased satiety . These attributes make P0C6A0 agonists a treatment option in type 2 diabetes mellitus ( T2DM ) . To optimise treatment choice , a detailed understanding of the effects of P0C6A0 RAs on glucose homeostasis in individuals with T2DM is necessary . Although the various P0C6A0 RAs share the same basic mechanisms of action , differences in pharmacokinetic/pharmacodynamic characteristics translate into differential effects on parameters of glycaemia . Head-to-head comparisons between long-acting non-prandial ( liraglutide once daily and exenatide once weekly ) and shorter-acting prandial ( exenatide twice daily and lixisenatide once daily prandial ) P0C6A0 RAs confirm their differential effects on fasting plasma glucose ( FPG ) and post-prandial glucose ( PPG ) . DB06655 once daily and exenatide once weekly demonstrate greater reductions in FPG but lesser impacts on PPG excursions plasma than exenatide twice daily . Prandial P0C6A0 RAs have a profound effect on post-prandial glycaemia , mediated by delaying gastric emptying , which is not subject to the tachyphylaxis occurring due to the sustained elevated plasma P0C6A0 concentrations after treatment with long-acting P0C6A0 RAs . DB09265 once-daily prandial , in contrast to liraglutide , strongly suppresses post-prandial glucagon secretion , further contributing to the more pronounced PPG-lowering effect found with lixisenatide . Evidence suggests that the P0C6A0 RAs that predominantly target the prandial glucose excursions , such as exenatide twice daily and lixisenatide once-daily prandial , are therefore best used as combination therapy with basal insulin and will form an important new treatment option for individuals with T2DM . Persistent Cdk2 inactivation drives growth arrest of P11274 - P00519 -expressing cells in response to dual inhibitor of P12931 and P00519 kinases SKI606 . Complementary inhibition of tyrosine and P12931 kinases implement dual P12931 / P00519 inhibitor effects in chronic myeloid leukemia ( CML ) . Here , we show that one such inhibitor , DB06616 , induces persistent Cdk2 inactivation leading to growth arrest of P11274 - P00519 -expressing cells either IM-sensitive or driven to IM-resistance by other events than gene overexpression and point mutations . Inhibition of Akt serine/threonine kinase , a phosphatidylinositol 3 kinase ( PI-3k ) target that integrates Q92817 TK signaling with membrane-associated P12931 kinases , is a central component of restored expression and subcellular redistribution of Cdk2 regulatory signals ( P38936 and p27 and Cdc25A phosphatase ) in response to DB06616 . The putative roles of growth factor ( namely P08700 ) autocrine loop in P11274 - P00519 -expressing progenitor progression towards a drug-resistant phenotype are discussed . Discovery and optimization of sulfonyl acrylonitriles as selective , covalent inhibitors of protein phosphatase methylesterase-1 . The serine hydrolase protein phosphatase methylesterase-1 ( Q9Y570 ) regulates the methylesterification state of protein phosphatase 2A ( PP2A ) and has been implicated in cancer and Alzheimer 's disease . We recently reported a fluorescence polarization-activity-based protein profiling ( fluopol- P05067 ) high-throughput screen for Q9Y570 that uncovered a remarkably potent and selective class of aza-β-lactam ( P00519 ) Q9Y570 inhibitors . Here , we describe a distinct set of sulfonyl acrylonitrile inhibitors that also emerged from this screen . The optimized compound , 28 ( AMZ30 ) , selectively inactivates Q9Y570 and reduces the demethylated form of PP2A in living cells . Considering that 28 is structurally unrelated to P00519 inhibitors of Q9Y570 , these agents , together , provide a valuable set of pharmacological probes to study the role of methylation in regulating PP2A function . We furthermore observed that several serine hydrolases were sensitive to analogues of 28 , suggesting that more extensive structural exploration of the sulfonyl acrylonitrile chemotype may result in useful inhibitors for other members of this large enzyme class . Enhancement of retroviral infection in vitro by anti-Le(y) IgG : reversal by humanization of monoclonal mouse antibody . Monoclonal mouse IgG3 antibody ( P00519 364 ) against the carbohydrate Le(y) antigen enhanced infection in vitro with HTLV-1 and with HIV-1 when propagated in both transformed and normal lymphocytes . Enhancement was independent of complement , occurred with both lymphocytes and monocytes as target cells , and did not use either L(ey) epitopes on target cells for cross-linkage of virus to the cell or the Fc part of the antibody as a ligand for any cellular receptor . For enhancement to occur , binding of anti-Le(y) antibody to virus was required to take place before virus binding to its specific receptor with no indication of any alternative pathway of infection , as evidenced by abrogation of enhancement by anti- P01730 MAb or soluble recombinant P01730 , and also the inability of anti-Le(y) MAb to mediate HIV infection of DB01040 -2 cells in which HTLV-1/HIV pseudovirus infection was enhanced . While F(ab)2 fragments of P00519 364 also enhanced infection , a human/mouse chimeric antibody and a fully humanized antibody had no enhancing effect on free virus infection . We suggest that binding of anti-Le(y) P00519 364 or its F(ab)2 fragment induced a conformational change in the gp120 oligomers facilitating the process of infection , and that this function was abrogated by the IgG1 Fc of the chimeric and the humanized antibodies . The observations indicate that the non-paratope domains of antiviral antibodies can influence their function as neutralizing or enhancing for infection . Tumour cell radiosensitization using constitutive ( CMV ) and radiation inducible ( P38936 ) promoters to drive the P35228 gene : a novel suicide gene therapy . DB00435 ( NO(*) ) has many characteristics including cytotoxicity , radiosensitization and anti-angiogenesis , which make it an attractive molecule for use in cancer therapy . We have investigated the use of P35228 gene transfer , driven by both a constitutive ( CMV ) and X-ray inducible ( P38936 ) promoter , for generating high concentrations of NO(*) within tumour cells . We have combined this treatment with radiation to exploit the radiosensitizing properties of this molecule . Transfection of murine Q9HBH0 -1 tumour cells in vitro with the P35228 constructs resulted in increased P35228 protein levels . Under hypoxic conditions cells were radiosensitized by delivery of both constructs so that these treatments effectively eliminated the radioresistance observed under hypoxic conditions . In vivo transfer of the CMV/ P35228 construct by direct tumour injection resulted in a delay ( 4.2 days ) in tumour growth compared with untreated controls . This was equivalent to the effect of 20 Gy X-rays alone . Combination of CMV/ P35228 gene transfer with 20 Gy X-rays resulted in a dramatic 19.8 day growth delay compared with controls . Tumours treated with the CMV/ P35228 showed large areas of necrosis and abundant apoptosis . We believe that P35228 gene transfer has the potential to be a highly effective treatment in combination with radiotherapy . Chronic rapamycin restores brain vascular integrity and function through NO synthase activation and improves memory in symptomatic mice modeling Alzheimer 's disease . Vascular pathology is a major feature of Alzheimer 's disease ( AD ) and other dementias . We recently showed that chronic administration of the target-of-rapamycin ( TOR ) inhibitor rapamycin , which extends lifespan and delays aging , halts the progression of AD-like disease in transgenic human (h) P05067 mice modeling AD when administered before disease onset . Here we demonstrate that chronic reduction of TOR activity by rapamycin treatment started after disease onset restored cerebral blood flow ( Q03701 ) and brain vascular density , reduced cerebral amyloid angiopathy and microhemorrhages , decreased amyloid burden , and improved cognitive function in symptomatic hAPP ( AD ) mice . Like acetylcholine ( ACh ) , a potent vasodilator , acute rapamycin treatment induced the phosphorylation of endothelial nitric oxide ( NO ) synthase ( P29474 ) and NO release in brain endothelium . Administration of the NOS inhibitor L-NG- DB04223 methyl ester reversed vasodilation as well as the protective effects of rapamycin on Q03701 and vasculature integrity , indicating that rapamycin preserves vascular density and Q03701 in AD mouse brains through NOS activation . Taken together , our data suggest that chronic reduction of TOR activity by rapamycin blocked the progression of AD-like cognitive and histopathological deficits by preserving brain vascular integrity and function . Drugs that inhibit the TOR pathway may have promise as a therapy for AD and possibly for vascular dementias . DB04866 suppresses the lung metastasis of chemically induced hepatocellular carcinoma in rats through MMP inhibition . DB04866 , an inhibitor of collagen synthesis , appears to be a promising antitumoral drug in preclinical studies . We used a relevant rat model of autochthonous , chemically induced , spontaneously metastasizing hepatocellular carcinoma ( HCC ) to test the efficacy of halofuginone on tumor progression and matrix metalloproteinase ( MMP ) expression . Following sequential administration of diethylnitrosamine and N-nitrosomorpholine for 14 weeks , all animals developed HCC and then received halofuginone or its solvent for 10 weeks . The final number of liver tumors was lower in the halofuginone group than in the solvent group ( 57.2 +/- 4.6 vs 68 +/- 5.0 ; P < .01 ) . The percentage of the lung surface infiltrated by metastasis was much smaller in the halofuginone group ( 0.3 +/- 0.2 % ) than in the solvent group ( 13.5 +/- 10.1 % ; P < .02 ) . P14780 activity was decreased in the halofuginone group by 89 % and 63 % in non-neoplastic parts of the liver and tumor , respectively . The percentage of active P08253 was reduced by 90 % in non-neoplastic parts of the liver and by 61 % in tumors . This was likely subsequent to a decreased expression of both P50281 and tissue inhibitor of matrix metalloproteinase-2 , which are required for pro- P08253 activation . These results , obtained from a clinically relevant model , further suggest the potential benefit of halofuginone in HCC . Inhibitory effects of imatinib on vitamin D₃ synthesis in human keratinocytes . Chronic myeloid leukemia ( CML ) is a myeloproliferative disease characterized by the presence of the BCR‑ P00519 fusion gene , a constitutively active , oncogenic tyrosine kinase that is responsible for the clinical features of CML . Tyrosine kinase inhibitors , such as imatinib , have markedly altered the treatment of CML . However , tyrosine kinase inhibitors are associated with side effects on bone metabolism , in adult and pediatric patients . DB00169 is involved in the complex cycle of bone remodeling , therefore the present study aimed to investigate the influence of imatinib on vitamin D3 metabolism in the HaCaT human keratinocyte cell line , using commercially available enzyme assays . Imatinib was shown to significantly reduce the production of calcidiol and calcitriol . Based on interaction studies of imatinib with the cytochrome P450 ( CYP450 ) inhibitors VID400 and ketoconazole , it is proposed that imatinib may interfere with the vitamin D3 cascade due to its metabolism by O15528 , which is involved in vitamin D3 metabolism . Increased serum levels of neutrophil gelatinase-associated lipocalin in patients with essential thrombocythemia and polycythemia vera . Neutrophil gelatinaase-associated lipocalin ( P80188 ) is a glycoprotein bound with matrix metalloproteinase-9 ( P14780 ) in human neutrophils , and elevated tissue P80188 expression has been documented in different infectious and inflammatory conditions . Recent evidence suggests that P80188 expression is induced in many types of human cancer . Moreover , P80188 is required for P11274 - P00519 -induced tumorigenesis . The aim of the present study was to measure serum levels of P80188 in patients with essential thrombocythemia ( ET ) and polycythemia vera ( PV ) . We also evaluated P80188 levels in patients with ET and PV with and without thrombotic events , to explore a possible correlation of P80188 with platelet and leukocyte activation , and in patients with sepsis . Serum P80188 levels in the study population were significantly higher than in healthy adults and in subjects with sepsis . A correlation between P80188 and the number of white cells and neutrophils was found in patients with PV and ET . P80188 serum levels were not different depending on the presence or not of the O60674 mutation , and a mutant allele dosage effect was not observed for P80188 levels . Patients with PV and ET with thrombosis did not have significantly higher levels of P80188 . We were unable to demonstrate a significant association between serum P80188 levels and CD11b or CD62 expression . In conclusion , our study reports evidence demonstrating that increased levels of P80188 appear to be a characteristic of patients with PV and ET . DB11582 suppresses osteoclastogenesis induced by O14788 and cancer cells through inhibition of inflammatory pathways : a new use for an old drug . BACKGROUND AND PURPOSE : Most patients with cancer die not because of the tumour in the primary site , but because it has spread to other sites . Common tumours , such as breast , multiple myeloma , and prostate tumours , frequently metastasize to the bone . To search for an inhibitor of cancer-induced bone loss , we investigated the effect of thiocolchicoside , a semi-synthetic colchicoside derived from the plant Gloriosa superba and clinically used as a muscle relaxant , on osteoclastogenesis induced by receptor activator of NF-κB ligand ( O14788 ) and tumour cells . EXPERIMENTAL APPROACH : We used RAW 264.7 ( murine macrophage ) cells , a well-established system for osteoclastogenesis , and evaluated the effect of thiocolchicoside on O14788 -induced NF-κB signalling and osteoclastogenesis as well as on osteoclastogenesis induced by tumour cells . KEY RESULTS : DB11582 suppressed osteoclastogenesis induced by O14788 , and by breast cancer and multiple myeloma cells . Inhibition of the NF-κB pathway was responsible for this effect since the colchicoside inhibited O14788 -induced NF-κB activation , activation of IκB kinase ( IKK ) and suppressed inhibitor of NF-κBα ( IκBα ) phosphorylation and degradation , an inhibitor of NF-κB . Furthermore , an inhibitor of the IκBα kinase γ or NF-κB essential modulator , the regulatory component of the IKK complex , demonstrated that the NF-κB signalling pathway is mandatory for osteoclastogenesis induced by O14788 . CONCLUSIONS AND IMPLICATIONS : Together , these data suggest that thiocolchicoside significantly suppressed osteoclastogenesis induced by O14788 and tumour cells via the NF-κB signalling pathway . Thus , thiocolchicoside , a drug that has been used for almost half a century to treat muscle pain , may also be considered as a new treatment for bone loss . Synergism between bosutinib ( DB06616 ) and the Chk1 inhibitor ( PF-00477736 ) in highly imatinib-resistant P11274 /ABL⁺ leukemia cells . Interactions between the dual P11274 / P00519 and Src inhibitor bosutinib and the Chk1 inhibitor PF-00477736 were examined in P11274 / P00519 (+) leukemia cells , particularly imatinib-resistant cells , including those with the T315I mutation . Bosutinib blocked PF-00477736-induced P27361 /2 activation and sharply increased apoptosis in association with Mcl-1 inhibition , p34(cdc2) dephosphorylation , BimEL up-regulation , and DNA damage in imatinib-resistant CML or Ph(+) ALL cell lines . Inhibition of Src or Q02750 by shRNA significantly enhanced PF-0047736 lethality . Bosutinib/PF-00477736 co-treatment also potentiated cell death in P28906 (+) CML patient samples , including dasatinib-resistant blast crisis cells exhibiting both T315I and E355G mutations , but was minimally toxic to normal P28906 (+) cells . Finally , combined in vivo treatment significantly suppressed BaF3/T315I tumor growth and prolonged survival in an allogeneic mouse model . Together , these findings suggest that this targeted combination strategy warrants attention in IM-resistant CML or Ph(+) ALL . P29323 activation causes epilepsy by stimulating DB01221 receptor activity . The P29323 MAPK signalling pathway is a highly conserved kinase cascade linking transmembrane receptors to downstream effector mechanisms . To investigate the function of P29323 in neurons , a constitutively active form of Q02750 ( caMEK1 ) was conditionally expressed in the murine brain , which resulted in P29323 activation and caused spontaneous epileptic seizures . P29323 activation stimulated phosphorylation of eukaryotic translation initiation factor 4E ( P06730 ) and augmented DB01221 receptor 2B ( Q13224 ) protein levels . Pharmacological inhibition of Q13224 function impaired synaptic facilitation in area cornus ammonicus region 3 ( P07451 ) in acute hippocampal slices derived from caMEK1-expressing mice and abrogated epilepsy in vivo . In addition , expression of caMEK1 caused phosphorylation of the transcription factor , DB02527 response element-binding protein ( CREB ) and increased transcription of ephrinB2 . EphrinB2 overexpression resulted in increased Q13224 tyrosine phosphorylation , which was essential for caMEK1-induced epilepsy in vivo , since conditional inactivation of ephrinB2 greatly reduced seizure frequency in caMEK1 transgenic mice . Therefore , our study identifies a mechanism of epileptogenesis that links Q96HU1 kinase to Eph/Ephrin and DB01221 receptor signalling . Immune reconstitution following rabbit antithymocyte globulin . Depletional induction therapies are routinely used to prevent acute rejection and improve transplant outcome . The effects of depleting agents on T-cell subsets and subsequent T-cell reconstitution are incompletely defined . We used flow cytometry to examine the effects of rabbit antithymocyte globulin ( DB00098 ) on the peripheral T-cell repertoire of pediatric and adult renal transplant recipients . We found that while DB00098 effectively depleted CD45RA+ P26842 + naïve and CD45RO+ P26842 + central memory P01730 + T cells , it had little effect on CD45RO+ P26842 - P01730 + effector memory or CD45RA+CD31- , CD45RO+ P26842 + and CD45RO+ P26842 - CD8+ T cell subsets . When we performed a kinetic analysis of CD31+ recent thymic emigrants and CD45RA+/RO+ T cells , we found evidence for both thymopoiesis and homeostatic proliferation contributing to immune reconstitution . We additionally examined the impact of DB00098 on peripheral P01730 +Foxp3+ T cells . We found that in adults , administration of DB00098 -induced peripheral expansion and new thymic emigration of T cells with a Treg phenotype , while P01730 +Foxp3+ T cells of thymic origin predominated in children , providing the first evidence that DB00098 induces Treg in vivo . Collectively our data indicate that DB00098 alters the balance of regulatory to memory effector T cells posttransplant , providing an explanation for how it positively impacts transplant outcome . Effects of neurosteroids on Ca(2+) signaling mediated by recombinant N-methyl-D-aspartate receptor expressed in Chinese hamster ovary cells . DB02789 sulfate ( PREGS ) potentiates the N-methyl-D-aspartate ( DB01221 ) receptor-mediated Ca(2+)-signals in cultured hippocampal neurons . The DB01221 receptor family has several different subunits whose expression in neurons has distinct spatial and temporal patterns . To examine subunit specificity of the PREGS action , we have investigated the effect of PREGS on recombinant GluR epsilon2/zeta1 ( Q13224 / Q9UHB4 ) type DB01221 receptors stabley expressed in Chinese hamster ovary cells using heat shock promoters . PREGS enhanced the Ca(2+) influx through the GluR epsilon2/zeta1 receptors in a dose-dependent manner . The EC(50) of PREGS for the GluR epsilon2/zeta1 receptors was 8.6 microM . Other sulfated neurosteroids , DB05804 ( DHEAS ) , 17beta-estradiol sulfate and 3alpha-ol-5beta-pregnan-20-one sulfate ( 3alpha5betaS ) , inhibited the positive modulatory effect of PREGS on the GluR epsilon2/zeta1 DB01221 receptors . DB08954 , a specific inhibitor of GluR epsilon2 subunit , abolished the DB01221 -induced Ca(2+) influx even in the presence of PREGS . These results imply that PREGS positively modulates the Ca(2+) influx through the GluR epsilon2/zeta1 receptors which are expressed from the embryonic period . The ability to accumulate deoxyuridine triphosphate and cellular response to thymidylate synthase ( TS ) inhibition . P04818 ( TS ) is an important enzyme catalysing the reductive methylation of DB03800 to dTMP that is further metabolized to dTTP for DNA synthesis . Loss of viability following TS inhibition occurs as a consequence of depleted dTTP pools and at least in some cell lines , accumulation of dUTP and subsequent misincorporation of uracil into DNA . The expansion in dUTP pools is largely determined by the expression of the pyrophosphatase , P33316 . Our previous work has shown that following TS inhibition the ability to accumulate dUTP was associated with an earlier growth inhibitory effect . 3 human lung tumour cell lines and HT29 human colon tumour cells transfected with P33316 have been used to investigate the relationship between loss of viability following TS inhibition and dUTP accumulation . Cell cycle arrest typical of TS inhibition was an early event in all cell lines and occurred irrespective of the ability to accumulate dUTP or p53 function . However , a large expansion of dUTP pools was associated with mature DNA damage ( 4 h ) and an earlier loss of viability following TS inhibition compared to cells in which dUTP pools were not expanded . In A549 cells damage to mature DNA may have been exacerbated by significantly higher activity of the excision repair enzyme , uracil-DNA glycosylase . Consistent with results using different inhibitors of TS , transfection of P33316 into HT29 cells significantly reduced the cytotoxicity of a 24 h but not 48 h exposure to ZD9331 . Although loss of viability can be mediated through dTTP deprivation alone , the uracil misincorporation pathway resulted in an earlier commitment to cell death . The relevance of this latter pathway in the clinical response to TS inhibitors deserves further investigation . Vitamin D metabolism , mechanism of action , and clinical applications . DB00169 is made in the skin from 7-dehydrocholesterol under the influence of UV light . DB00153 ( ergocalciferol ) is derived from the plant sterol ergosterol . Vitamin D is metabolized first to 25 hydroxyvitamin D ( 25OHD ) , then to the hormonal form 1,25-dihydroxyvitamin D ( 1,25(OH)2D ) . Q6VVX0 is the most important 25-hydroxylase ; O15528 is the key 1-hydroxylase . Both 25OHD and 1,25(OH)2D are catabolized by Q07973 . 1,25(OH)2D is the ligand for the vitamin D receptor ( P11473 ) , a transcription factor , binding to sites in the DNA called vitamin D response elements ( VDREs ) . There are thousands of these binding sites regulating hundreds of genes in a cell-specific fashion . P11473 -regulated transcription is dependent on comodulators , the profile of which is also cell specific . Analogs of 1,25(OH)2D are being developed to target specific diseases with minimal side effects . This review will examine these different aspects of vitamin D metabolism , mechanism of action , and clinical application .