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 promoter region of the liver/bone/ kidney-type alkaline phosphatase gene was examined to define the cis-acting regulatory sequences and transcription factors responsible for its expression in hematopoietic cells. Transient transfection experiments revealed that regions deleted up to -154 base pairs upstream from the transcription initiation site had significant activities to induce bacterial chloramphenicol acetyltransferase gene. The shortest DNA fragment was found to contain three GC boxes in addition to a TATA box. Electrophoretic mobility shift assay and Southwestern analysis showed that Sp3 could bind to the fragment. Western blot analysis also detected Sp3 protein in eluate from the DNA probe mixed with the nuclear extracts. Through the use of Drosophila Schneider cells that lack the Sp1 family of transcription factors, Sp3 was shown to activate the basal promoter in a dose-dependent manner. When the amount of Sp3 was limited, the most proximal GC box was found to be critical for the basal promoter activity.
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PMID:Transcription factor Sp3 activates the liver/bone/kidney-type alkaline phosphatase promoter in hematopoietic cells. 1107 19

Cystathionine beta-synthase (CBS) catalyzes the condensation of serine and homocysteine to form cystathionine, an intermediate step in the synthesis of cysteine. We previously characterized the CBS -1b minimal promoter (-3792 to -3667) and found that Sp1/Sp3, nuclear factor Y, and USF-1 were involved in the regulation of basal promoter activity (Ge, Y., Konrad, M. A., Matherly, L. H., Taub, J. W. (2001) Biochem. J. 357, 97-105). In this study, the critical cis-elements and transcription factors in the CBS -1b upstream region (-4046 to -3792) were examined in HT1080 and HepG2 cells, which differ approximately 10-fold in levels of CBS transcripts transcribed from the CBS -1b promoter. In DNase I footprint and gel shift analyses and transient transfections of mutant CBS -1b promoter constructs into HT1080 and HepG2 cells, transcriptionally important roles for Sp1/Sp3 binding to three GC boxes and one GT box and for binding of myeloid zinc finger 1-like proteins to two myeloid zinc finger 1 elements were indicated. In gel shift assays, very low levels of Sp1/Sp3 DNA-protein complexes were detected in HT1080 cells compared with HepG2 cells despite comparable levels of nuclear factor Y and USF-1 binding and similar levels of Sp1 and Sp3 proteins on Western blots. Mixing of HT1080 and HepG2 nuclear extracts resulted in no difference in total Sp factor binding in gel shift assays, thus excluding a role for an unknown activator or inhibitor in the disparate Sp1/Sp3 binding between the lines. Increased Sp1/Sp3 binding in gel shift assays was observed upon treatment of HT1080 nuclear extracts with protein kinase A, and decreased Sp1/Sp3 binding resulted from treatment of HepG2 nuclear extracts with calf alkaline phosphatase, suggesting a role for changes in Sp1/Sp3 phosphorylation in transcription factor binding and transactivation of the CBS -1b promoter. Characterization of CBS promoter structure and function should clarify the molecular bases for variations in CBS gene expression in genetic diseases and the relationship between CBS and Down syndrome.
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PMID:Transcriptional regulation of cell-specific expression of the human cystathionine beta -synthase gene by differential binding of Sp1/Sp3 to the -1b promoter. 1156 58

Keratoconus is a potentially blinding disease that thins the central cornea. In afflicted corneas, the level of an inhibitor, alpha1-proteinase inhibitor (alpha1-PI), is found reduced. An increased expression of transcription factor Sp1 is also demonstrated. To examine the role of Sp1 in regulation of the human alpha1-PI gene, a 1.4-kb (-1397/+9) 5'-flanking promoter sequence that contains 10 Sp1 sites was cloned. Previous transient transfection experiments showed that Sp1 expression indeed repressed the alpha1-PI promoter activity. In this study, 12 DNA segments, a series of 5', 3', and internal deletions of the 1.4-kb alpha1-PI promoter sequence, were ligated into the SEAP (secreted alkaline phosphatase) reporter gene vector and transfected into human corneal stromal cells. Co-transfection with a Sp1 expression vector pPacSp1 was also performed in parallel. The SEAP enzyme activity was assayed. A fragment with 489 bp (-480/+9) of the 3' sequence, and three fragments with internal deletions, were found to confer a majority of the full promoter activity. Other deletions significantly abolished the promoter activity. Site-directed mutagenesis experiments further revealed that the most proximal Sp1 site (-100/-87) may be an essential element involved in the negative regulation of alpha1-PI promoter activity by Sp1. Interaction between the proximal and distal Sp1 sites also seemed to be important. These results provide the first in-depth characterization of the transcription mechanisms regulating the expression of alpha1-PI. Mapping of the Sp1 sites may help elucidate the molecular pathway leading to the alterations observed in keratoconus.
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PMID:Mapping of Sp1 regulation sites in the promoter of the human alpha1-proteinase inhibitor gene. 1196 87

The product of the leptin gene is a 16-kDa protein secreted by adipose tissue and regulates adiposity. The leptin gene could be a potential candidate gene controlling some proportion of adipose and lean accretion in cattle, and thus, may be referred to as one of genetic factor controlling meat quality determinants such as marbling. We have isolated the bovine leptin gene including its promoter region. We have determined the exon-intron organization of the bovine leptin gene, which consisted of three exons and two introns and spanned about 18.9 kb, equivalent to that of human or mouse gene. A approximately 3-kb 5'-flanking region upstream from the putative transcription start site of the gene contained consensus Sp1 and CCAAT/enhancer-binding protein (C/EBP) motifs, and transient transfection assay with secreted alkaline phosphatase reporter confirmed the promoter activity in 3T3-L1 cells that possessed expression of the cotransfected C/EBP alpha expression plasmid. Cotransfection with C/EBP alpha caused 24-fold activation in leptin reporter expression, as compared to cotransfection with control plasmid, consistent with existence of the putative C/EBP alpha binding site in the proximal 5'-flanking region of the bovine leptin gene.
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PMID:Genomic structure and promoter analysis of the bovine leptin gene. 1204 96

Previous studies have shown that progestin increases the content of progesterone receptor (hPRA and hPRB) and the hPR mRNA during decidualization of human endometrial stromal cells suggesting that endogenous hPR enhances the transcription of the hPR gene. In the present study, we provide evidence that hPR regulates the promoter activity mediated through an active Sp1 site. In stromal cells treated with medroxyprogesterone acetate, the promoter activity was significantly increased when cells were co-transfected with hPR expression vector. Progressive deletion analysis showed that the highest activity was derived from the promoter region between -55 and +31 bp. Transactivation by hPR was dose dependent. The capacity of hPRA was stronger than that of hPRB. The ligand binding domain, but not DNA binding domain of the hPR was required for the transactivation. The proximal promoter region lacks a canonical progesterone response element. Instead, an active Sp1 site (-49 to -43 bp) has been confirmed. Mutation of the Sp1 site eliminated the effect of hPR activation. The promoter activity was increased by over expression of Sp1, whereas Sp3 had no effect. Electrophoretic mobility shift assay showed that the promoter region between -55 and +31 bp bound to Sp1 family proteins, Sp1 (C2 complex) and Sp3 (C1 and C3 complexes) identified by antibodies to Sp1 and Sp3. Sp1 complex formed by extracts of stromal cells was less intense than that formed by progestin-decidualized stromal cells. Sp1/DNA binding was enhanced when stromal cell extracts were incubated with calf intestine alkaline phosphatase (CIP) suggesting that dephosphorylation of Sp1 enhances the DNA binding. Addition of protein kinase inhibitor, H-89 or H-7, enhanced the hPR stimulated promoter activity. Western blot analysis showed that endometrial stromal/decidual cell extracts contained a wide band of Sp1 spanning from approximately 105 to 96 kDa and was resolved into one band at 96 kDa by CIP. Decidual cell extracts are abundant with the 96 kDa Sp1. In addition, the 96 kDa Sp1 was co-precipitated with ligand-activated hPRA or hPRB in the decidual cell nuclear extracts. These data suggest that dephosphorylated Sp1, abundant in decidual cells, enhances the binding to both DNA and hPR resulting in a robust increase of the hPR promoter activity.
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PMID:Progesterone receptor activates its promoter activity in human endometrial stromal cells. 1208 66

Children with Down syndrome (DS) with acute myeloid leukemia (AML) have significantly higher event-free survival rates compared to those with non-DS AML, linked to greater cytosine arabinoside (ara-C) sensitivity and higher transcript levels of the chromosome 21-localized gene, cystathionine-beta-synthase (CBS), in DS myeloblasts. In this study, we examined the transcriptional regulation of the CBS gene in the DS megakaryocytic leukemia (AMkL) cell line, CMK, characterized by significantly higher CBS transcripts compared with the non-DS AMkL cell line, CMS. Rapid amplification of 5'-cDNA ends (5'-RACE) analysis demonstrated exclusive use of the CBS -1b promoter in the cell lines, and transient transfections with the full-length CBS -1b luciferase reporter gene construct showed 40-fold greater promoter activity in the CMK than CMS cells. Electrophoretic mobility shift assays showed enhanced binding of the transcription factors Sp1/Sp3 to 2 GC/GT-box elements (GC-f and GT-d) in the upstream regions of the CBS -1b promoter in CMK nuclear extracts and undetectable binding in CMS cells. Mutation of the GC-f- or GT-d-binding site resulted in an approximately 90% decrease of the CBS -1b promoter activity in transient transfections of CMK cells. Chromatin immunoprecipitation assays confirmed in vivo binding of Sp3, USF-1, and nuclear factor YA (NF-YA) to the CBS -1b promoter region in chromatin extracts of CMK and CMS cells. Decreased binding of Sp1/Sp3 in CMK nuclear extracts following treatment with calf alkaline phosphatase suggested a role for phosphorylation of Sp1/Sp3 in regulating CBS promoter activity and in the differential CBS expression between CMK and CMS cells. The results of this study with clinically relevant cell line models suggest potential mechanisms for disparate patterns of CBS gene expression in DS and non-DS myeloblasts and may, in part, explain the greater sensitivity to chemotherapy shown by patients with DS AML.
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PMID:Transcriptional regulation of the cystathionine-beta -synthase gene in Down syndrome and non-Down syndrome megakaryocytic leukemia cell lines. 1239 9

This study demonstrates that in vitro exposure of adult rat alveolar epithelial cells to CdCl(2) decreases DNA binding activity of specificity protein 1 (Sp1), a zinc-finger transcription factor known to play a key role in eukaryotic gene expression, maintenance of homeostasis, cell cycle control, terminal differentiation, and apoptosis. Suppression of Sp1 function, as assessed by electrophoretic mobility shift assays (EMSAs), is dependent upon cadmium (Cd) dose and duration of exposure. A 45% decrease of Sp1 activity occurs as early as 30 min after Cd addition. By 2 h, Sp1 activity is reduced even further with no loss of cell viability, suggesting that Sp1 inactivation precedes cell death. If Cd is removed from cultures during these early periods of exposure, inhibition of Sp1 binding activity is reversed. Sp1 inactivation does not appear to be a generalized, non-selective response to Cd as other transcription factors are up-regulated under the same conditions. Phosphorylation is involved in Sp1 down-regulation, as evidenced by the finding that alkaline phosphatase treatment of nuclear extracts from cells exposed to Cd for 2 h helps restore Sp1 binding activity. A broad spectrum Protein Kinase C (PKC) inhibitor, GF109203X, substantially reduces the Cd-mediated effect on Sp1 suggesting that a member of the PKC family is required for Sp1 phosphorylation. More prolonged Cd exposure promotes Sp1 degradation with the appearance of cleavage products (40 and 50 kDa), as detected by Western blotting. Changes in the integrity of the Sp1 protein are accompanied by a corresponding decline in cell survival. Cd-induced cell death is substantially attenuated if cells are pretreated with antagonists of PKC activity which implies that a PKC isoform is also a participant in this process.
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PMID:Mechanisms regulating the cadmium-mediated suppression of Sp1 transcription factor activity in alveolar epithelial cells. 1249 19

Previously, several important cis-elements and trans-factors have been shown to play a functional role in the proximal promoter of mouse mu-opioid receptor (MOR) gene. In this study, we defined another functional element located the in -450 to -400 bp (translational start site designated as +1) region of the proximal promoter, which is also essential for the full promoter activity. It is designated as the morAP-2-like element for its sequence homologous to the consensus AP-2 element. Surprisingly, electrophoretic mobility shift analysis (EMSA) revealed that Sp1 and Sp3, but not AP-2 proteins, were specifically bound to the morAP-2-like element. Mutation of the morAP-2-like element, resulting in a loss of Sp binding, led to an approximately 35% decrease in activity, further confirming the positive role of the morAP-2-like element in MOR gene expression. Dephosphorylation of Sp proteins with alkaline phosphatase also decreased Sp binding to the morAP-2-like element in EMSA, suggesting phosphorylation of Sp is essential for its binding to this element. However, direct or indirect activation of PKA, a classical G-protein coupled signaling pathway, resulted in no significant change of Sp binding to the morAP-2-like element, nor of the promoter activity the SH-SY5Y cells, MOR expressing cells, suggesting that phosphorylation of Sp does not involve PKA. These results suggest that the binding of different phosphorylated forms of Sp proteins to the morAP-2-like element may contribute to the fine tuning of MOR expression in different cells.
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PMID:Role of an AP-2-like element in transcriptional regulation of mouse mu-opioid receptor gene. 1267 Jul 13

The reduced folate carrier (RFC) is the dominant influx transporter for antifolates. A major mechanism of antifolate resistance is loss of RFC (SLC19A1) gene expression due to decreased GC-box-dependent transcription. However, despite the poor GC-box binding in multiple antifolate-resistant cell lines, normal Sp1 levels were retained. Here we explored the post-translational modifications that may disrupt Sp1 function. Phospho-affinity purification of nuclear proteins revealed that resistant cells contained approximately 8-fold more phosphorylated Sp1 than parental cells; treatment of nuclear proteins from these cells with alkaline phosphatase restored GC-box binding. As protein kinase A phosphorylates Sp1, resistant cells were treated with various cAMP-reactive agents, revealing no apparent effect on GC-box binding except for the general phosphodiesterase inhibitor IBMX. As cGMP levels also may be affected by IBMX, resistant cells were treated with 8-pCPT-cGMP, resulting in the complete restoration of GC-box binding, luciferase reporter activity, and RFC mRNA levels. This restoration was abolished in the presence of the protein phosphatase 2A inhibitor (PP2A) okadaic acid. Importantly, whereas resistant cells showed multiple phosphorylated Sp1 forms barely detectable in parental cells, treatment with 8-pCPT-cGMP resulted in their elimination; this disappearance, however, was prevented by the copresence of okadaic acid. These findings provide the first evidence that loss of RFC gene expression in antifolate-resistant cells is associated with an inhibitory Sp1 phosphorylation that can be eliminated by a cGMP-dependent activation of PP2A.
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PMID:Loss of Sp1 function via inhibitory phosphorylation in antifolate-resistant human leukemia cells with down-regulation of the reduced folate carrier. 1616 3

Inhibitors of histone deacetylases (HDACs) induce growth arrest, differentiation, and apoptosis of colon cancer cell lines in vitro and have demonstrated anti-cancer efficacy in clinical trials. Whereas a role for HDAC1 and -2 in mediating components of the HDAC inhibitor response has been reported, the role of HDAC3 is unknown. Here we demonstrate increased protein expression of HDAC3 in human colon tumors and in duodenal adenomas from Apc1638(N/+) mice. HDAC3 was also maximally expressed in proliferating crypt cells in normal intestine. Silencing of HDAC3 expression in colon cancer cell lines resulted in growth inhibition, a decrease in cell survival, and increased apoptosis. Similar effects were observed for HDAC2 and, to a lesser extent, for HDAC1. HDAC3 silencing also selectively induced expression of alkaline phosphatase, a marker of colon cell maturation. Concurrent with its effect on cell growth, overexpression of HDAC3 and other Class I HDACs inhibited basal and butyrate-induced p21 transcription in a Sp1/Sp3-dependent manner, whereas silencing of HDAC3 stimulated p21 promoter activity and expression. However, the magnitude of the effects elicited by silencing of individual Class I HDACs was significantly less than that induced by HDAC inhibitors. These findings identify HDAC3 as a gene deregulated in human colon cancer and as a novel regulator of colon cell maturation and p21 expression. These findings also demonstrate that multiple Class I HDACs are involved in repressing p21 and suggest that the growth-inhibitory and apoptotic effects induced by HDAC inhibitors are probably mediated through the inhibition of multiple HDACs.
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PMID:Histone deacetylase 3 (HDAC3) and other class I HDACs regulate colon cell maturation and p21 expression and are deregulated in human colon cancer. 1653 12


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