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 spindle pole body (SPB) is the equivalent of the centrosome in fission yeast. In vivo it nucleates microtubules (MTs) during mitosis, but, unlike animal centrosomes, does not act as a microtubule organizing center (MTOC) during interphase. We have studied the MT-nucleating activity of SPBs in vitro and have found that SPBs in permeabilized cells retain in vivo characteristics. SPBs in cells permeabilized during mitosis can nucleate MTs, and are recognized by two antibodies: anti-gamma-tubulin and MPM-2 which recognizes phosphoepitopes. SPBs in cells permeabilized during interphase cannot nucleate MTs and are only recognized by anti-gamma-tubulin. Interphase SPBs which cannot nucleate can be converted to a nucleation competent state by incubation in cytostatic factor (CSF)-arrested Xenopus egg extracts. After incubation, they are recognized by MPM-2, and can nucleate MTs. The conversion does not occur in Xenopus interphase extract, but occurs in Xenopus interphase extract driven into mitosis by preincubation with exogenous cyclin B. The conversion is ATP dependent and inhibited by protein kinase inhibitors and alkaline phosphatase. Purified, active, cdc2 kinase/cyclin B complex in itself is not effective for activation of MT nucleation, although some interphase SPBs are now stained with MPM-2. These results suggest that the ability of SPBs in vitro to nucleate MTs after exposure to CSF-arrested extracts is activated through a downstream pathway which is regulated by cdc2 kinase.
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PMID:In vitro microtubule-nucleating activity of spindle pole bodies in fission yeast Schizosaccharomyces pombe: cell cycle-dependent activation in xenopus cell-free extracts. 153 43

Interphase cytosol extracts prepared from Xenopus laevis eggs are active in RNA polymerase III (Pol III) transcription. Addition of recombinant B1 cyclin to these extracts activates mitotic protein kinases that repress transcription. Affinity-purified p34cdc2-cyclin B kinase (mitosis-promoting factor) is sufficient to effect this repression in a simplified Pol III transcription system. This mitotic repression involves the direct phosphorylation of a component of the Pol III transcription initiation factor TFIIIB, which consists of the TATA box-binding protein (TBP) and associated Pol III-specific factors. The transcriptional activity of the TFIIIB-TBP fraction can be modulated in vitro by phosphorylation with mitotic kinases and by dephosphorylation with immobilized alkaline phosphatase.
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PMID:Mitotic repression of RNA polymerase III transcription in vitro mediated by phosphorylation of a TFIIIB component. 827 69

Lymph nodes from 21 cases of malignant lymphoma of a centrocytic (mantle cell) type, (ML, cc (mc)) were examined. All the cases had monoclonal surface immunoglobulin (sig) M and/or D, but were negative for CD10 (CALLA), and CD11c (LeuM5). Lymphoma cells with CD25 (anti-Tac)+, CD5 (Leu1)+, and alkaline phosphatase (ALPase)- in eight cases showed bone marrow involvement (10-66% of the nucleated cells; mean 32 +/- 18%) but with no leukemic changes. These eight cases had a similar phenotype and were distributed by the lymphoma cells to the examined B-chronic lymphocytic leukemia. Seven cases showed an infiltration of CD25-, CD5+, and ALPase- lymphoma cells, in which only two cases showed focal bone marrow involvement. There was a close relationship between CD25 expression and bone marrow invasion by the lymphoma cells in ML, cc (mc). Three of the six CD25- and CD5- cases presented zonal proliferation of ALPase+ lymphoma cells with round nuclei and a high anti-proliferating cell nuclear antigen/cyclin (PCNA/c) rate in the mantle zone and paracortex, accompanied by a prominent interdigitating dendritic and histiocytic cell reaction. Examined CD25-, CD5- and ALPase+ lymphoma showed a neoplastic counterpart of so-called marginal zone lymphocytes, which was different from other cases of ML, cc (mc). Lymphoma cells in ML, cc (mc), except for those of the so-called marginal zone lymphoma, might be derived from slgM+, D+/-, CD25+/-, CD5+/-, ALPase-, CD10- and CD11c- lymphocytes present in the mantle zone and primary lymph follicles.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinicopathologic, enzyme and histochemical studies of centrocytic (mantle cell) lymphoma: comparison with other types of low-grade B cell lymphoma based on the updated Kiel classification. 832 10

Stable, nonradioactive riboprobes were used in ribonuclease protection assays to monitor the changes in cyclin mRNA expression during cell cycle progression in human mammary epithelial cells. Probes labeled with biotin demonstrated sufficient sensitivity (comparable to 32P) to detect these low-abundance mRNAs and thus offer a safe and easy alternative to traditional radioactive assays. Three detection systems based on chemiluminescence generated by horseradish peroxidase or alkaline phosphatase were compared for sensitivity, background and ease of use.
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PMID:Detection of cyclin messenger RNAs by nonradioactive ribonuclease protection assay: a comparison of four detection methods. 858 15

The PH081 gene product functions as an inhibitor of the cyclin-cyclin-dependent kinase pair, Pho80-Pho85, and is required for derepression of acid phosphatase-encoding gene (PH05) expression. PH081 is the only known regulator of this system whose transcriptional expression is regulated by the level of inorganic phosphate. This effect is mediated by the gene products of the PH04 and PH02 (BAS2, GRF10) genes which act as transcription factors. Fine structural analysis of the PH081 promoter region has revealed the existence of a negative regulatory sequence (NRS). That is, removal of this element causes an approx. 4-fold increase in PH081 expression. The NRS functions in either orientation, but only when located downstream from activation sequences. Interestingly, this element shows significant homology to a sequence present in the promoter of the PH08 gene, encoding a phosphate-repressible alkaline phosphatase. An electrophoretic mobility shift assay (EMSA) using whole-cell extracts and a NRS-containing DNA fragment detects a protein which specifically binds to this element.
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PMID:Negative transcriptional regulation of PH081 expression in Saccharomyces cerevisiae. 862 60

We have analysed the recircularisation of plasmid DNA, cut with two different endonucleases to generate non-homologous DNA ends, in extracts of unfertilised eggs and oocytes of Xenopus. We found that the capacity to join non-homologous DNA ends, generating diagnostic covalently closed monomer circles, appeared during oocyte maturation at the time of germinal vesicle breakdown. This enzyme function was post-translationally activated in oocyte extracts incubated with unfertilised egg extract containing active cdc2/cyclin B, or by incubation with purified cdc2/cyclin B. Dephosphorylation of egg proteins by alkaline phosphatase inhibited the ability to join non-homologous DNA ends. We show that most linear non-homologous DNA ends repaired to form closed-circular supercoiled monomers, are joined without loss of nucleotides. Following partial purification, the activity was inhibited by inhibitors of poly(ADP-Rib) polymerase, an enzyme that is inactive in oocytes, but phosphorylated and activated during maturation. Competitive inhibition of poly(ADP-Rib) polymerase by > 50 microM 3-aminobenzamide prevented the joining of both matched and non-homologous DNA ends. We conclude that post-translational phosphorylation provides one route by which end-joining of non-homologous DNA can be regulated.
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PMID:Post-translational activation of non-homologous DNA end-joining in Xenopus oocyte extracts. 926 93

1Alpha,25(OH)2 vitamin D3 (1,25(OH)2D3) can induce differentiation of osteoblastic cells by arresting the cell cycle at G1. The p53-inducible gene, WAF1/Cip1, is one of the inhibitors of cyclin-dependent kinases and can inhibit the phosphorylation of retinoblastoma protein (pRB), thereby keeping pRB functionally active. Here we show that in a p53-null human osteoblastic osteosarcoma MG-63 cell line, 10 nM of 1,25(OH)2D3 completely inhibits cell growth and increases alkaline phosphatase activity, which suggests the induction of osteoblastic differentiation. We also found a p53-independent increase of WAF1/Cip1 mRNA and promoter activation by 1,25(OH)2D3. On the other hand, the expression and the promoter activity of the RB gene decreased after treatment with 1,25(OH)2D3 during the differentiation of MG-63 cells. Our results suggest that the p53-independent WAF1/Cip1 induction by 1,25(OH)2D3 is important for osteoblastic differentiation of MG-63 cells.
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PMID:p53-independent induction of WAF1/Cip1 is correlated with osteoblastic differentiation by vitamin D3. 971 36

The cellular mechanisms regulating intestinal proliferation and differentiation remain largely undefined. Previously, we showed an early induction of the cyclin-dependent kinase (CDK) inhibitor p21(Waf1/Cip1) in Caco-2 cells, a human colon cancer line that spontaneously differentiates into a small bowel phenotype. The purpose of our present study was to assess the timing of cell cycle arrest in relation to differentiation in Caco-2 cells and to examine the mechanisms responsible for CDK inactivation. Caco-2 cells undergo a relative G1/S block and cease to proliferate at day 3 postconfluency; an increase in the activity of terminally differentiated brush-border enzymes (sucrase and alkaline phosphatase) was noted at day 6 postconfluency. Cell cycle block was associated with suppression of both CDK2 and CDK4 activities, which are important for G1/S progression. Treatment of the CDK immune complexes with the detergent deoxycholate (DOC) resulted in restoration of CDK2, but not CDK4, activity at day 3 postconfluency, suggesting the presence of inhibitory protein(s) binding to the cyclin/CDK2 complex at this time point. An increased binding of p21(Waf1/Cip1) to CDK2 complexes at day 3 postconfluency was noted, suggesting a potential role for p21(Waf1/Cip1) in CDK2 inactivation; however, immunodepletion of p21(Waf1/Cip1) from Caco-2 protein extracts demonstrated that p21(Waf1/Cip1) is only partially responsible for CDK2 suppression at day 3 postconfluency. A decrease in the cyclin E/CDK2 complex appears to contribute to the CDK2 inactivation noted at days 6 and 12 postconfluency. Taken together, our results suggest that multiple mechanisms contribute to CDK suppression during Caco-2 cell differentiation. Inhibition of CDK2 and CDK4 leads to G1 arrest and inhibition of proliferation that precede Caco-2 cell differentiation.
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PMID:Caco-2 intestinal cell differentiation is associated with G1 arrest and suppression of CDK2 and CDK4. 981 65

Butyrate, a short-chain fatty acid produced in the colon, reduces proliferation and increases differentiation of colon cancer cells. p27, an inhibitor of cyclin-dependent kinases and a negative regulator of the cell cycle, is thought to have a key function in the differentiation of various cell lines. The objective of the present study was to elucidate the role of p27 in butyrate-induced differentiation of the human colorectal carcinoma cell line Caco-2. In this report we show that in spite of the increase in p27 protein expression after incubation with the HMG-CoA reductase inhibitor mevastatin, alkaline phosphatase activity decreases significantly in this cell line. In addition, mevastatin caused a significant increase in the cell cycle inhibitor p21. All effects could be reversed by addition of mevalonate to the medium. Taken together, we provide the first evidence that in Caco-2 cells p27 may have other functions apart from the regulation of cell differentiation.
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PMID:Butyrate-induced differentiation of Caco-2 cells occurs independently from p27. 1118 Oct 44

Monoclonal antibody 12D11 (MAb 12D11) has been shown to bind histone H1 isolated from human placenta and other tissues but not histone H1 that has been digested with bacterial alkaline phosphatase. We show here that phosphorylation of phosphatase-treated histone H1 with cyclin dependent-kinase (CDK) restores binding by MAb 12D11. We conclude that MAb 12D11 selectively binds histone H1 that has been phosphorylated by CDKs, and we have investigated the use of MAb 12D11 as an immunohistochemical probe of CDK activity in situ. Previous immunofluorescence studies have revealed strong nuclear staining by MAb 12D11 in proliferating cultured cells and the absence of staining in terminally differentiated cells. Immunohistochemical staining of frozen and formalin-fixed, paraffin-embedded sections of benign tissues with MAb 12D11 was nuclear and confined to recognized foci of cell proliferation. In lymphoid germinal centers, MAb 12D11 preferentially stained large lymphoid cells with a relative lack of staining in small cleaved cells, contrasting with a lack of cell size discrimination observed with the monoclonal antibody proliferation probe, MIB-1. Tumor tissues displayed strong albeit heterogeneous staining of malignant cells by MAb 12D11, with little or no staining observed in surrounding nonneoplastic stromal cells. Differential staining by MAb 12D11 of invasive and in situ carcinoma suggest applications in prognostication. MAb 12D11 may also be useful in identification of tumors more likely to respond to therapeutic CDK inhibitors.
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PMID:Monoclonal antibody specific for histone H1 phosphorylated by cyclin-dependent kinases: a novel immunohistochemical probe of proliferation and neoplasia. 1211 7


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