Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Simian virus 40 (SV40) entry leading to infection occurred only after the virus was at the cell surface for 1.5 to 2 h. SV40 infectious entry was not sensitive to cytosol acidification, a treatment that blocks endocytosis via clathrin-coated vesicles. Instead, SV40 infectious entry was blocked by treating cells with the phorbol ester PMA or nystatin, which selectively disrupts caveolae. In control experiments, transferrin internalization was sensitive to cytosol acidification but was not sensitive to PMA or nystatin. Also, absorbed transferrin entered cells within minutes. Finally, bound SV40 translocated to caveolin-enriched membrane complexes isolated by a Triton X-100 insolubility protocol. Treatment with nystatin did not impair SV40 binding but did block the partitioning of virus into the caveolin-enriched complexes.
Mol Biol Cell 1996 Nov
PMID:Bound simian virus 40 translocates to caveolin-enriched membrane domains, and its entry is inhibited by drugs that selectively disrupt caveolae. 893 Sep 3

Neutral sphingomyelinase (SMase) can be activated by extracellular signals to produce ceramide, which may affect mitogen-activated protein kinase (MAPK) activities. Neutral SMase activity was assessed in membranes from Jurkat, a human T-cell line, and EL4, a murine T-cell line. Ara-C activated SMase with 10 minutes in both Jurkat and EL4 cells, while phorbol ester (PMA) had no effect. PMA, but not Ara-C or ceramides, activated ERK MAPKS, in Jurkat and EL4. PMA acted synergistically with ionomycin to activate JNK MAPKs in Jurkat and EL4 within 10 minutes. Ara-C activated JNKs only after prolonged incubation (90-120 minutes). Thus, ceramide is not a positive signal for ERK activation in T-cell lines. The effects of Ara-C on JNK activity may be mediated through secondary response pathways.
Biochem Mol Biol Int 1996 Nov
PMID:Effects of Ara-C on neutral sphingomyelinase and mitogen- and stress-activated protein kinases in T-lymphocyte cell lines. 895 29

We have characterized the nuclear and cytoplasmic RNA transcripts derived from the gonadotropin releasing hormone (GnRH) gene in a mouse hypothalamic neuronal GT1 cell line. Analyses of nuclear GnRH RNA precursors present in the GT1 cells by RNase protection assay show that there is no particular order of intron excision, suggesting the existence of multiple processing pathways. A similar pattern is observed in mouse preoptic area-anterior hypothalamus (POA-AH). In GT1 cells, approximately 5% of the total GnRH RNA transcripts are found in the nucleus. In contrast, in the POA-AH of mice, nuclear transcripts comprise 40% of the total GnRH transcripts. Thus the GT1 cells, while similar in overall GnRH RNA processing to mouse hypothalamic GnRH neurons, do not exhibit the high abundance of nuclear GnRH RNA transcripts seen in the rodent GnRH neuron in vivo. Quantitative analysis of the nuclear RNA species shows that the GnRH primary transcript comprises more than 90% of the total nuclear GnRH mRNA precursors in both GT1 cells and mouse POA-AH and thus GnRH processing intermediates account for fewer than 10% of these precursors. Using these probes, we have examined changes in GnRH primary transcript expression in GT1-7 cells. In the presence of RNA synthesis inhibitors, the half-life of the GnRH primary transcript was found to be quite short, approximately 18 min, suggesting that the level of primary transcript would reflect levels of GnRH gene transcription. When GT1-7 cells are treated with the phorbol ester PMA (phorbol, 12-myristate, 13-acetate) for 1 h, GnRH primary transcript levels decrease by approximately 70%. Supporting the hypothesis that GnRH primary transcript is a good indicator of GnRH gene transcription is the finding that 1 h of PMA treatment results in a similar (approximately 50%) decrease in GnRH gene transcription, as assayed by nuclear run-on assay. Our observation that GT1 cells resemble mouse hypothalamic GnRH neurons in their pattern of intron excision and in the ratio of primary transcript to other nuclear transcripts emphasizes the utility of these cells for studying the regulation of GnRH gene expression in this immortalized hypothalamic cell line.
Brain Res Mol Brain Res 1996 Dec
PMID:Characterization of gonadotropin-releasing hormone gene transcripts in a mouse hypothalamic neuronal GT1 cell line. 901 81

Microtubules are integral components of the cytoskeleton of human cells and are composed of alpha- and beta-tubulin as well as a variable number of microtubule-associated proteins. In monocytes and macrophages, microtubules bind endotoxin and partly regulate endotoxin-induced inflammatory events such as cytokine production. Endotoxin causes a rapid alteration in monocyte microtubule stability. To characterize the effect of endotoxin on mononuclear phagocyte microtubule composition, Western blots and flow cytometry were performed on human monocytes and the monocyte/macrophage-like cell line THP-1. Compared to unstimulated monocytes, monocytes stimulated with endotoxin for 18 h had increased quantities of alpha-, beta-, and tyrosinated alpha-tubulin as well as microtubule-associated protein-2. PMA-differentiated THP-1 cells had increased levels of alpha-tubulin, beta-tubulin, microtubule-associated protein-5, microtubule-associated protein-2, and tau after endotoxin stimulation. These results indicate that endotoxin can alter mononuclear phagocyte microtubules by causing an increase in certain microtubule component proteins.
Am J Respir Cell Mol Biol 1997 Feb
PMID:Changes in mononuclear phagocyte microtubules after endotoxin stimulation. II. Changes in microtubule composition. 903 19

Extracellular nucleotides stimulate mucin release by binding to the P2u receptor coupled to phospholipase C via G proteins (Br. J. Pharmacol. 103:1053-1056, 1991; Am. J. Respir. Cell Mol. Biol. 8:121-125, 1993). In the present study, we intended to investigate pathways downstream to the phospholipase C activation which is responsible for adenosine triphosphate (ATP)-induced mucin release in hamster tracheal epithelial cells in primary culture. We have found that: (1) Ca2+ ionophores (A23187 and ionomycin) did not affect mucin release even at 1 microM; (2) thapsigargin (10 microM), either alone or in combination with ATP (20 microM), did not enhance mucin release over its respective control group; (3) pretreatment of hamster tracheal surface epithelial (HTSE) cells with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) (50 microM) did not inhibit ATP-induced mucin release; (4) 4beta-phorbol 12alpha-myristate 13-acetate (PMA, 1 microM) stimulated mucin release and its effect was completely blocked by protein kinase C inhibitors such as sphingosine (10 microM) and calphostin C (0.1 microM), whereas ATP-induced mucin release was blocked, only in part, by these inhibitors; (5) desensitization of protein kinase C by pretreatment with PMA inhibited the PMA-induced mucin release completely, however, ATP-induced mucin release was inhibited only partially. We conclude that mucin release by ATP does not require an increase in the intracellular Ca2+ level but involves the activation of protein kinase C. The results also suggest the presence of another mechanism separate from the phospholipase C-protein kinase C pathway for the ATP-induced mucin release.
Am J Respir Cell Mol Biol 1997 Feb
PMID:ATP-induced mucin release from cultured airway goblet cells involves, in part, activation of protein kinase C. 903 27

The presence and subcellular localization of the Ca2+-dependent protein kinase C (PKC) isoforms alpha and beta were investigated in freshly isolated adult rat cardiac ventricular myocytes. PKC activity was measured in cytosolic and particulate fractions prepared from control myocytes and those treated with either phorbol ester (phorbol 12-myristate 13-acetate, PMA) or a permeant synthetic diacylglycerol analog (1-oleoyl-2-acetylglycerol, OAG) in the absence or presence of an inhibitor of diacylglycerol kinase activity, compound R59022. Preliminary studies detected no Ca2+-/phospholipid-dependent histone kinase activity in either subcellular fraction. To reproducibly observe Ca2+-/phospholipid-dependent protein kinase activity, partial purification using a MonoQ HR 5/5 column and the presence of the peptide inhibitor of the cAMP-dependent protein kinase were essential. MonoQ chromatography of cytosolic and particulate fractions resulted in three peaks of Ca2+/phospholipid-dependent protein kinase activity. In the cytosolic fraction a large peak of activity eluted at 230-300 mM NaCl. Isoform-specific antisera indicated both PKC alpha and PKC beta were present. In the particulate fraction two peaks of Ca2+-/phospholipid-dependent protein kinase activity, both containing PKCa immunoreactivity, were observed. The larger peak eluted at 230-300 mM NaCl. In addition, a peak eluting at lower salt concentrations contained a Ca2+-/phospholipid-independent histone kinase activity. This peak of kinase activity contained PKC alpha immunoreactive bands of 80- and 50-kDa. The 80-kDa band was the holoenzyme of PKC alpha whereas the band of lower molecular mass was likely a proteolytic fragment. In both cytosolic and particulate fractions, the peak of kinase activity eluting at 230-300 mM NaCl contained PKC alpha in the form of an 80-kDa doublet; this suggested the presence of autophosphorylated PKC. Incubation of the myocytes with PMA, but not OAG, resulted in translocation of PKC from the cytosolic to the particulate fraction. Curiously, a transient decrease in PKC activity was observed in both subcellular fractions following treatment with either OAG or ethanol (1%). Results from this study show that freshly isolated adult rat cardiac ventricular myocytes contain both PKC alpha and PKC beta, and that these isoforms translocate to the particulate fraction in response to treatment with PMA, but not OAG.
Mol Cell Biochem 1997 Jan
PMID:Characterization of calcium-dependent forms of protein kinase C in adult rat ventricular myocytes. 904 17

Interactions between erythropoietin (Epo) and its receptor (EpoR) are critical for the normal proliferation and differentiation of erythroid progenitor cells. EpoR is expressed in low numbers during early stages of erythroid maturation, while higher levels are expressed during later stages, suggesting that the expression of the EpoR gene is tightly regulated throughout erythropoiesis. We used the TF-1 erythroleukemia cell line to analyze the effects of various cytokines and reagents on the regulation of human EpoR gene expression. Human EpoR gene expression was significantly upregulated by IL-1 alpha and the protein inhibitor cycloheximide, but significantly downregulated by the calcium ionophore ionomycin and the phorbol ester PMA. These effects on EpoR gene expression were not due to changes in EpoR mRNA stability, suggesting that these agents directly affected EpoR gene transcription. The selective in vitro modification of EpoR expression by these agents highlights the complexity of human EpoR gene expression, and provides clues to its in vivo regulation.
Blood Cells Mol Dis 1996
PMID:Regulation of expression of the human erythropoietin receptor gene. 907 72

The mechanisms by which GnRH modulates synthesis of LH beta subunit and release of LH from the pituitary gonadotropes are not clearly understood. However, GnRH actions in the pituitary gonadotropes have been suggested to be mediated by the PKC- and/or cAMP-dependent pathways. Thus, in the present study we have examined 1) whether the activations of either the PKC- and/or cAMP-dependent signaling cascades could elevate the levels of LH beta mRNA, and if so, 2) whether this increase of LH beta mRNA levels is the result of transcriptional activation or the result of suppressing the turnover of LH beta mRNA. In the present experiment, the activators of protein kinase C and the adenylate cyclase, PMA (5 nM) and forskolin (10 microM) respectively, have elevated the steady state levels of LH beta mRNA significantly by 18 h at the specific concentrations shown in the parenthesis. Subsequently, we have determined whether the elevation of LH beta mRNA levels by either PMA or forskolin is due to the new synthesis of LH beta mRNA or the suppression of LH beta mRNA turnover. Result showed that the ability of PMA or forskolin to elevate the LH beta mRNA levels was suppressed by the addition of actinomycin D, an inhibitor of transcription. Result further showed that the turnover of LH beta mRNA was not suppressed either by PMA or forskolin. These results indicate that the activation of PKC as well as the elevation of cAMP by GnRH leads to the increase in the levels of LH beta mRNA by stimulating the new synthesis of LH beta mRNA instead of increasing the stability of pre-existing LH beta mRNA.
Mol Cells 1997 Feb 28
PMID:cAMP and protein kinase C elevate LH beta mRNA levels by activating transcription rather than stabilizing mRNA in rat pituitary cells. 908 72

The effect of infra-red laser irradiation has been experimented on various biological systems and particularly in human tissues, in vitro as well as in vivo. In order to examine the influence of laser irradiation on cells of the monocytic lineage we have irradiated human peripheral blood mononuclear cells with an infra-red laser at a wavelength of 904 nm, at 2000 Hz frequency and 15 mW for 2 min. Here, we report that laser irradiation for 2 min. at different preincubation times (T = 0 and T = 30 min) enhances LPS (10 micrograms/ml or PHA (10 micrograms/ml, suboptimal concentration)-stimulated monocytes by modifying cell proliferation, as judged by [3H] thymidine incorporation. IL-1 receptor antagonist (IL-1ra) along with an increased release of [3H] Arachidonic acid production, is also influenced by laser irradiated monocytes when treated for 2 min after 1 h incubation. IL-1RA production increased 4-5 fold after laser irradiation, while 3H-arachidonic acid incorporated from PMA-stimulated cells increased and the effect was significant at T = 0 and T = 30 min; while at T = 1 h the effect was negligible. These results may provide new information regarding the effect of laser irradiation on the immune system.
Mol Cell Biochem 1997 Apr
PMID:Infra-red laser irradiation enhances interleukin-1 receptor antagonist, increases 3H-thymidine incorporation and the release of [3H]arachidonic acid in human monocytes. 908 31

This study was undertaken parthenogenetically to activate Chinese hamster oocytes in vitro by chemical stimuli. Oocytes were exposed to five different chemical agents, ethanol (EtOH), strontium chloride (SrCl2), cycloheximide (CHX), phorbol ester (PMA), and ionophore A23187 (IA23). No parthenogenetic activation was observed in the oocytes treated with 8% EtOH for 8-11 min, 1.7 mM and 5.0 mM SrCl2 for 1 hr, 100 microM and 400 microM CHX for 2 hr, and 81 nM and 162 nM PMA for 5 min. In contrast, 89.7% of oocytes parthenogenetically extruded the second polar body in treatment with 3 microM IA23 for 5 min, but only 22.6% of them formed a pronucleus and developed to 2-cell embryos. The remaining ova stopped their cell cycle immediately after completion of the second meiotic division. They had unichromatid chromosomes (monads), which are called MIII chromosomes. Treatment with 5 microM IA23 for 5 min was so deleterious that > 90% of oocytes were degenerated. However, oocyte activation was significantly improved when the treatment with 3 microM IA23 for 5 min was followed by treatment with 8% EtOH for 10 min, 100 microM CHX for 2 hr, 81 nM PMA for 5 min or 3 microM IA23 for 5 min: rates of pronuclear formation were 54.4%, 84.3%, 34.2%, and 54.6%, respectively. More than 80% of pronucleate ova successfully developed into 2-cell stage. Additive treatment with 5 mM SrCl2 for 1 hr had no positive effect on pronuclear formation. Incidences of aneuploidy (4.6%) and structural chromosome aberrations (1.0%) in parthenogenons produced by combined stimuli of IA23 and CHX were not significantly different from those (3.8% and 1.6%, respectively) in female pronuclei of ova fertilized in vitro, showing that combined treatments with IA23 and CHX cause neither nondisjunction at the second meiotic division nor structural aberrations in MII chromosomes. The present technique for parthenogenetic activation of Chinese hamster oocytes may be useful as an assessment system to detect aneugenic and clastogenic effects of mutagens on mammalian oocytes.
Mol Reprod Dev 1997 May
PMID:Parthenogenetic activation of Chinese hamster oocytes by chemical stimuli and its cytogenetic evaluation. 911 Mar 17


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