Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fluorescent Dye H33342 (H342) is a bis-benzimidazole used for intravital fluorescent staining. In this report, we found that H342 completely abolished histone 2a mRNA but had no effect on alkaline phosphatase gene expression and protein synthesis in UMR 106-01 rat osteoblast-like cells. The complete loss of histone 2a mRNA occurred after only 20 min of treatment with H342. This effect is unlikely to be a result of inhibition of DNA synthesis, which was only partly suppressed. The mechanism of the action of H342 on histone 2a mRNA is presently unknown.
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PMID:Expression of histone and alkaline phosphatase genes in UMR 106-01 rat osteoblast-like cells exposed to the Hoechst dye H33342. 844 Jul 51

Previous studies on the intestinal epithelium from various species have shown that the number of alpha 2-adrenergic receptors in immature cells from the crypts is several-fold higher than in mature cells from the villi, thus suggesting an inverse relationship between enterocytic differentiation and the expression of this inhibitory receptor. The receptor density along the surface-crypt axis of the human colonic mucosa is correlated with the amount of alpha 2C10 mRNA; however, the mechanisms underlying this regulation remain unknown. The human colonic adenocarcinoma cell line HT29, which expresses the alpha 2A-adrenergic receptor and is able to undergo enterocytic differentiation, is a suitable model with which to investigate this question in vitro. In this study, we explored the effects of short chain fatty acids (SCFAs), differentiating agents normally present in the colon lumen, on alpha 2-adrenergic receptor expression. Exposure of HT29 cells to butyrate and propionate, but not acetate, resulted in a large diminution of [3H]RX821002 binding sites. The reduction of alpha 2-adrenergic receptor number induced by butyrate or propionate was due to decreased amounts of alpha 2C10 mRNA and was associated with an increase of alkaline phosphatase activity, which reflected the emergence of a more differentiated phenotype. The changes in alpha 2C10 mRNA level induced by both SCFAs were dose-dependent, rapid, and reversible and resulted from a diminution in the transcription rate of the alpha 2C10 gene. Finally, these effects were mimicked by trichostatin A, indicating that they are triggered primarily through inhibition of histone deacetylases. The present findings demonstrate that decrease of alpha 2-adrenergic receptor expression is a very early event of the HT29 cell differentiation process. They also suggest that SCFAs, which originate from bacterial fermentation of dietary fibers, may play a role in the regulation of the alpha 2-adrenergic receptivity of colonic mucosa in vivo.
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PMID:Regulation of alpha 2A-adrenergic receptor expression in the human colon carcinoma cell line HT29: SCFA-induced enterocytic differentiation results in an inhibition of alpha 2C10 gene transcription. 886 48

The histochemical and cytochemical localization of acid phosphatase has been used in an attempt to map the sites of cellular lysis and death. Reaction product was found both in the brush border of the midgut epithelium and in the basal membrane. Vacuolar acid phosphatase activity was found in the regenerative epithelial cells. Extra-cisternal reaction product was associated with the endoplasmic reticulum which was dilated in lysed areas of the cytoplasm. Free acid and alkaline phosphatase activity was found in the basal area of the midgut epithelial cells and the former also occurred in the haemocoel. In the tracheoblastic cells only vacuolar acid phosphatase activity was seen. Chromatin aggregates were distributed throughout the nucleus and the nuclear envelope showed some infolding. Certain mature epithelial cells proved positive for anti-histone associated DNA fragmentation indicative of programmed cell death.
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PMID:Programmed cell death in the honey-bee (Apis mellifera L.) larvae midgut. 915 91

Platelet-derived growth factor (PDGF) is mitogenic and chemotactic for osteoblastic cells in vitro. It is expressed during osseous wound healing and stimulates formation of new bone in vivo. PDGF stimulates cells by binding to specific cell surface receptors. The purpose of this study was to examine the effects of PDGF on osteoblastic proliferation and differentiation in long-term mineralizing cultures. Utilizing Northern blot analysis, we found that continuous PDGF treatment increased histone expression, indicative of enhanced proliferation, but suppressed osteoblast differentiation, demonstrated by inhibition of alkaline phosphatase, type I collagen, and osteocalcin expression. The inhibitory effect of PDGF on the differentiated function of osteoblasts was further established by findings that PDGF significantly inhibited nodule formation. The expression of PDGF receptors varied at different stages of culture. PDGF receptor mRNA expression increased when the cells had achieved a mature phenotype, during the stage of matrix maturation, and then decreased. However, as demonstrated by thymidine incorporation assays, the capacity of PDGF to stimulate DNA synthesis actually decreased during osteoblast maturation, as receptor expression increased. To investigate this apparent contradiction, tyrosyl phosphorylation and immunoblot assays were performed to assess changes in PDGF activation of their cognate receptors. The pattern of PDGF-induced tyrosyl phosphorylation remained relatively constant. This suggests that the diminished mitogenic activity of PDGF that occurs after osteoblast differentiation is regulated at a postreceptor level.
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PMID:Temporal expression of PDGF receptors and PDGF regulatory effects on osteoblastic cells in mineralizing cultures. 917 63

In this paper, specific PHO13 alkaline phosphatase from Saccharomyces cerevisiae was demonstrated to possess phosphoprotein phosphatase activity on the phosphoseryl proteins histone II-A and casein. The enzyme is a monomeric protein with molecular mass of 60 kDa and hydrolyzes p-nitrophenyl phosphate with maximal activity at pH 8.2 with strong dependence on Mg2+ ions and an apparent Km of 3.6 x 10(-5) M. No other substrates tested except phosphorylated histone II-A and casein were hydrolyzed at any significant rate. These data suggest that the physiological role of the p-nitrophenyl phosphate-specific phosphatase may involve participation in reversible protein phosphorylation. 1988 Federation of European Microbiological Societies.
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PMID:A specific alkaline phosphatase from Saccharomyces cerevisiae with protein phosphatase activity. 956 42

Short chain fatty acids such as sodium butyrate are concentrated in the colonic lumen and may protect against colon carcinogenesis by maintaining colonocytic differentiation, but the mechanisms by which they act are not fully understood. It has recently been suggested that short chain fatty acids modulate cellular tyrosine kinase activity in addition to altering chromatin structure via regulation of histone acetylation and DNA methylation. Therefore, the authors evaluated the influence of tyrosine kinase inhibition on the effects of 10 mM butyrate on human Caco-2 intestinal epithelial differentiation, using alkaline phosphatase and dipeptidyl dipeptidase specific activity as markers of differentiation, and two tyrosine kinase inhibitors, of different mechanisms of action and different effects on Caco-2 brush border enzyme specific activity, to block tyrosine kinase activity. As expected, butyrate stimulated both alkaline phosphatase and dipeptidyl dipeptidase specific activity. The tyrosine kinase inhibitors prevented, and indeed one inhibitor reversed the effects of butyrate on alkaline phosphatase specific activity. However, tyrosine kinase inhibition did not prevent butyrate stimulation of dipeptidyl dipeptidase specific activity. Different pathways are likely to regulate the effects of butyrate on expression of these two brush border enzymes. Butyrate stimulation of alkaline phosphatase, but not dipeptidyl dipeptidase, may involve tyrosine phosphorylation signaling.
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PMID:Tyrosine kinase inhibitors reverse butyrate stimulation of human Caco-2 intestinal epithelial cell alkaline phosphatase but not butyrate promotion of dipeptidyl dipeptidase. 1019 53

Plasmodial fragmin, a Physarum polycephalum F-actin severing and capping protein, is phosphorylated by casein kinase II at Ser(266) (De Corte, V., Gettemans, J., De Ville, Y., Waelkens, E., and Vandekerckchove, J. (1996), Biochemistry 35, 5472-5480). In this study, we report the purification and characterization of the corresponding fragmin phosphatases. One of the enzymes was purified to near homogeneity from a cytosolic extract; it dephosphorylates CKII-phosphorylated fragmin, a peptide encompassing the CKII phosphorylation site of fragmin as well as histone 2A, CKII-phosphorylated casein and the CKII model-peptide substrate: R(3)E(3)S(P)E(3). Its activity was highly stimulated by Mn(2+) and Mg(2+), and based on its lack of sensitivity toward phosphatase effectors we could exclude similarities with PP1, PP2A and PP2B phosphatases. All biochemical properties of the phosphatase point to a PP2C-like enzyme. A second phosphatase dephosphorylating fragmin was identified as a Physarum alkaline phosphatase.
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PMID:A novel endogenous PP2C-like phosphatase dephosphorylates casein kinase II-phosphorylated Physarum fragmin. 1111 5

In an attempt to elucidate the potential of premeiotic male germ cells to malignant transformation both the invasiveness and the differential gene expression of several putative tumor markers of the spermatogonia-derived cell line GC-1spg and the spermatocyte-derived cell line GC-4spc were analyzed. Studies, using RT-PCR analysis, of the expression pattern of the alkaline phosphatase isoenzymes which serve as markers for testicular germ cell tumors demonstrated that the expression of the endogenous mouse embryonic alkaline phosphatase (EAP) is upregulated in the GC-1spg cell line. Additionally, after transfection of GC-1spg cells and GC-4spc cells with a GCAP-CAT construct, an increased promoter activity of the human germ cell alkaline phosphatase (GCAP), the equivalent human isoenzyme of EAP, was shown in GC-1spg. Furthermore, an in vitro Matrigel invasion assay revealed a significant higher invasive potential of GC-1spg cells as compared to GC-4spc cells. Finally, a suppression subtractive hybridization on RNA of invasive GC-1spg cells and non-invasive GC-4spc cells was performed. In total, 31 cDNA sequences were isolated and further analyzed. Among these, 18 known sequences and 13 unknown sequences were determined. Northern blot analysis revealed that one unknown gene and eight known genes, namely integrin alpha 6, L6 antigen, annexin VIII, BVL-1 retrotransposon, protective protein, replacement variant histone 3.3, alpha-catenin and LPS-binding protein, are over-expressed in invasive GC-1spg cells. Taken together, both the enhanced invasive activity of GC-1spg cells and the upregulated expression of genes involved in the process of tumor progression suggest that the immortalized spermatogonia-derived cell line GC-1spg does have a higher potential to malignant transformation than the immortalized spermatocyte-derived cell line GC-4spc.
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PMID:Isolation and characterization of differentially expressed genes in invasive and non-invasive immortalized murine male germ cells in vitro. 1117 88

The nuclear structure changes during the differentiation from growing to infective stages of Trypanosoma cruzi. As histone modifications have been correlated with structural and functional changes of chromatin, we investigated whether histones in T. cruzi are modified during the life cycle of this protozoan parasite. We found that histone H1 isolated from proliferating forms (epimastigotes) and from differentiated/infective forms (trypomastigotes) have a distinct migrating pattern in Triton-acetic acid-urea gel electrophoresis. While epimastigotes contain predominantly a fast migrating form, a slow migrating band is prominent in trypomastigotes. By metabolically labeling the cells with radioactive phosphate, we demonstrated that the slow migrating histone H1 band is phosphorylated, and that after alkaline phosphatase treatment, it migrates as the fast form. Parasites arrested at the onset of the S phase of the cell cycle with hydroxyurea (HU) also predominantly have the phosphorylated form of histone H1, suggesting that phosphorylation occurs in non-replicating stages of T. cruzi. We also found that the phosphorylated histone H1 is more weakly associated with the chromatin, being preferentially released at 150 mM NaCl. Therefore, histone H1 phosphorylation varies during the life cycle of T. cruzi, and might be related to changes in the chromatin structure.
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PMID:Histone H1 is phosphorylated in non-replicating and infective forms of Trypanosoma cruzi. 1181 78

Although quantitative measurement of skeletal alkaline phosphatase (sALP) activity in serum can provide an index of the rate of bone formation, the metabolic process that determines the release of sALP - from the surface of osteoblasts, into circulation-is unknown. The current studies were intended to examine the hypothesis that the release of sALP from human osteoblasts is a consequence of apoptotic cell death. We measured the release of sALP activity from human osteosarcoma (SaOS-2) cells and normal human bone cells, under basal conditions and in response to agents that increased apoptosis (TNF-a, okadiac acid) and agents that inhibit apoptosis (IGF-I, calpain, and caspase inhibitors). Apoptosis was determined by the presence of nucleosomes (histone-associated DNA) in the cytoplasm of the cells by using a commercial kit. The results of these studies showed that TNF-a and okadiac acid caused dose- and time-dependent increases in apoptosis in the SaOS-2 cells (r = 0.78 for doses of TNF-a and r = 0.93 for doses of okadiac acid, P <0.005 for each), with associated decreases in cell layer protein (P <0.05 for each) and concomitant increases in the release of sALP activity (e.g., r = 0.89 for TNF-a and r = 0.75 for okadiac acid, P <0.001 for each). In contrast, caspase and calpain inhibitors reduced apoptosis, increased cell layer protein, and decreased the release of sALP activity (P <0.05 for each). Exposure to IGF-I also decreased apoptosis, in a time- and dose-dependent manner (e.g., r = 0.93, P <0.001 for IGF-I doses), with associated proportional effects to increase cell layer protein (P <0.001) and decrease the release of sALP activity (P <0.001). IGF-I also inhibited the actions of TNF-a and okadiac acid to increase apoptosis and sALP release. The associations between apoptosis and sALP release were not unique to osteosarcoma (i.e., SaOS-2) cells, but also seen with osteoblast-line cells derived from normal human bone. Together, these data demonstrate that the release of sALP activity from human osteoblast-line cells in vitro is associated with, and may be a consequence of, apoptotic cell death. These findings are consistent with the general hypothesis that the appearance of sALP activity in serum may reflect the turnover of osteoblast-line cells.
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PMID:Apoptosis may determine the release of skeletal alkaline phosphatase activity from human osteoblast-line cells. 1203 23


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