Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the last decades several markers of pancreatic neoplasia have been proposed to obtain a diagnosis as earlier as possible. Prerequisites of a good tumor marker are high sensitivity and specificity. Among the various substances, serum determination of pancreatic enzymes has been found of no utility in early diagnosis of pancreatic cancer, due to its lack in sensitivity and specificity. Similar results with ribonuclease and deoxyribonuclease. Oncofetal antigens (CEA and POA) have been initially considered promising indices; however, further studies showed their limits. In particular CEA is greatly influenced by the presence of hepatic metastases; therefore, serum levels are detectable only in advanced stages. TPA is characterized by a high sensitivity, but lacks in specificity and its use is now avoided. A real progress in the field of tumor markers has been made in the last years with the monoclonal antibody technique: among them CA 19-9 showed a good sensitivity and a satisfactory specificity as regards the diagnosis of pancreatic cancer. However, it cannot be considered as absolute aid, since it is influenced by several factors, as tumor spread, jaundice and liver dysfunction.
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PMID:[Value and limitations of neoplasm markers in the diagnosis of pancreatic carcinoma]. 204 59

Follistatin was originally identified as a specific inhibitor of follicle stimulating hormone secretion and later characterized as a binding protein for activin. Since activin regulates hormone secretion and cell differentiation, the importance of understanding the mechanisms regulating the synthesis of its binding protein, follistatin, is evident. To study the regulation of follistatin gene expression, we first determined the transcription start site (cap site) of the rat follistatin gene using primer extension and ribonuclease protection assay. Our results led to the identification of multiple cap sites located at three different positions of the promoter. DNA sequence analysis revealed that each cap site was located at approximately 30 nucleotide (nt) downstream of three distinct TATA-like sequences. In primary cultures of rat granulosa cells, transfection studies using 5'-flanking regions of follistatin gene fused to the chloramphenicol acetyltransferase (CAT) reporter gene revealed the presence of two DNA segments that act to suppress basal transcriptional activity. The promoter activity of the CAT construct containing 2.6 kilo base pairs (kb) of 5'-flanking region was induced 2.5-fold above basal activity by forskolin (10 microM), and 1.6-fold by 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 nM). Co-treatment with forskolin and TPA resulted in a 6.4-fold induction in its promoter activity, suggesting that two distinct signal transduction pathways, the cAMP-dependent protein kinase-A pathway and diacylglycerol-dependent protein kinase-C pathway, act coordinately to modulate follistatin gene transcription. Experiments using a series of 5'-flanking region deletion constructs located the regulatory regions responsive to these two pharmacological agents at nt -312 to -32 and -35 to +139.
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PMID:Structural and functional characterization of the rat follistatin (activin-binding protein) gene promoter. 847 73

The protein-kinase-C (PKC) family of iso-enzymes regulates mitogenic signal transduction in colorectal-cell lines. Its function in human colonic mucosal proliferation is controversial. Our study investigated the role of PKC with regard to proliferation and changes of PKC iso-enzyme expression in colonic biopsies compared with small adenomas. In short-term tissue-culture experiments of colonic mucosal biopsies, we found reduced S-phase labeling in the 2 apical compartments of longitudinally sectioned crypts when PKC was activated by 200 nM of the phorbol ester TPA (n = 8). Thus, PKC inhibited growth of differentiated colonocytes which may influence cell homeostasis in colonic crypts. Furthermore, we have determined the expression of PKC alpha, -beta1, -beta2, -delta and -epsilon in colonic adenomas smaller than 1 cm in diameter of 18 patients and found a significant increase of PKC alpha in the cytosolic fraction and decreased membrane levels of PKC beta2 in adenomas compared to normal, neighboring mucosa while protein levels of PKC beta1, -delta and -epsilon were not altered. Moreover PKC delta but not PKC alpha mRNA expression was significantly lowered in adenoma tissue in 7 patients, as determined by ribonuclease-protection analysis. Changes in the regulation patterns of PKC isoforms suggest a decreased activation state of PKC even in small adenomas. This is compatible with an anti-proliferative function of PKC serving to protect mucosa from expanding mutated cells.
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PMID:Anti-proliferative activity of protein kinase C in apical compartments of human colonic crypts: evidence for a less activated protein kinase C in small adenomas. 993 29

The molecular mechanisms involved in regulation of CRH-binding protein (CRH-BP) gene expression were examined using primary rat astrocyte cultures. The cells were treated with various regulators, and CRH-BP messenger RNA (mRNA) levels were determined using ribonuclease protection assays. Forskolin (Fsk, 10 microM) or 12-O-tetradecanoyl-phorbol 13-acetate (TPA, 100 nM) increases CRH-BP mRNA levels up to 30 times control level, and together they act synergistically to increase CRH-BP gene expression up to 100 times control levels. CRH can also positively regulate CRH-BP gene expression to 6.1 times control levels. All of these increases in steady-state CRH-BP mRNA levels can be repressed by dexamethasone, a synthetic glucocorticoid. To determine whether these changes in steady-state CRH-BP mRNA levels are caused by altered transcription or RNA stability, heteronuclear (hn) CRH-BP species were examined using ribonuclease protection assays. CRH-BP hnRNA transcripts can be detected transiently after the addition of Fsk or TPA, and dexamethasone can repress Fsk- or TPA-induced CRH-BP hnRNA levels in this assay. These results demonstrate that CRH, glucocorticoids, and the protein kinase A and protein kinase C signaling pathways are involved in regulation of CRH-BP gene expression in astrocyte cultures, and that this regulation is caused, at least in part, by altered transcription of the gene.
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PMID:Transcriptional regulation of corticotropin-releasing hormone-binding protein gene expression in astrocyte cultures. 1046 81