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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental models and clinical investigations have suggested that epidermal growth factor (EGF) may have a role in corneal wound healing. It has been identified as a normal component of human tears. Rabbit and mouse lacrimal glands have recently been shown to synthesize EGF messenger RNA (mRNA). The purpose of the present study was to determine whether the human lacrimal gland synthesizes EGF mRNA. Total cellular RNA was isolated from pathologic specimens of normal human lacrimal glands from two individuals. Reverse transcriptase was used to generate complementary DNA (cDNA) using a human EGF-specific mRNA primer. Amplification of EGF-related cDNA sequences was performed with the polymerase chain reaction (PCR) and human EGF-derived up- and downstream primers. The PCR products from both lacrimal glands contained an amplified product of the expected length of approximately 410 base pairs. The PCR-generated fragment was verified as an EGF-related amplification product with Southern blotting using a synthetic oligonucleotide probe derived from the mature coding sequence of EGF. These results conclusively demonstrate that the human lacrimal gland synthesizes EGF and suggest that the lacrimal gland could have a regulatory role in maintaining the ocular surface and possibly regulating corneal wound healing through the secretion of EGF.
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PMID:Epidermal growth factor messenger RNA production in human lacrimal gland. 172 72

A major unsolved problem in developmental biology is to determine when and how time- and position-restricted instructions are signaled and received during secondary embryonic inductions such as branching morphogenesis. The mouse embryonic lung rudiment was used to test the hypothesis that endogenous peptide growth factors, specifically epidermal growth factor (EGF), serve as instructive epigenetic signals for morphogenesis. The presence of EGF precursor mRNA transcripts was detected using the reverse-transcriptase-coupled polymerase chain reaction both in E11-E17-day mouse embryo lung tissues in vivo and in E11-day lung cultured for up to 7 days in vitro under chemically defined, serum-free conditions. Immunolocalization identified a position-restricted distribution of EGF in and around the primitive airways both during in vivo lung morphogenesis and in culture. EGF receptors (EGFR) coimmunolocalized with EGF in the primitive airways. Addition of exogenous EGF to lungs in culture resulted in significant concentration-dependent stimulation of branching morphogenesis, DNA, RNA, and protein content, and in [3H]thymidine incorporation into DNA. Conversely, the addition of tyrphostin (specific EGF receptor kinase antagonist) to lungs in culture resulted in concentration-dependent inhibition of branching morphogenesis, DNA, RNA, and protein content, and in [3H]thymidine incorporation into DNA without apparent cytotoxicity. The inhibition of the EGF signal by tyrphostin was confirmed by immunoprecipitation of tyrosine phosphoproteins. We conclude that early mouse embryo lungs express EGF transcripts and corresponding EGF peptides in a specific position-restricted distribution which coimmunolocalizes with EGFR in the primitive airways, while stimulatory and inhibitory studies indicate a functional role for the transduced EGF signal in the epigenetic regulation of lung branching morphogenesis. We speculate that the peptide growth factor EGF serves a function in secondary embryonic morphogenetic inductions, which may be modulated by interaction with other growth factors.
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PMID:Epigenetic role of epidermal growth factor expression and signalling in embryonic mouse lung morphogenesis. 172 82

Microvascular murine endothelial cells lines transformed by middle T oncogene of polyoma virus maintain the biological characteristics of nontransformed microvascular endothelial cells (EC). By using cell lines originated from different anatomical districts (thymus, brain, heart, and skin), we demonstrated that murine granulocyte-colony-stimulating factor (G-CSF) induces proliferation of murine microvascular endothelial cells at nanomolar concentrations without any cooperation with fetal calf serum. The proliferative effect on murine cells is less than that elicited by epidermal growth factor (EGF), used as standard for this function. G-CSF also promotes the migration of tEnd.1 endothelial cell line assayed by Boyden chamber technique. The analysis of transcript for G-CSF receptor (G-CSFR) by Northern blot hybridization and by reverse-transcriptase polymerase chain reaction (RT-PCR) shows that these cell lines have specific mRNA, with the size of that present in myeloid cells. These results indicate that G-CSF operates in the microvascular endothelial cells by a mechanism related to the presence of a specific receptor.
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PMID:Proliferative and migratory responses of murine microvascular endothelial cells to granulocyte-colony-stimulating factor. 768 23

The salivary glands of mammals synthesize and secrete a number of peptide growth factors that play important roles in cell/tissue homeostasis and embryonic development. Using a radioimmunoassay, insulin, insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II) were detected in saliva from mice. Unlike epidermal growth factor (EGF), there was no sexual dimorphism in the concentrations of the insulin growth factor family. Immunohistochemical localization of IGF-I and IGF-II was confined to the duct cells of both the parotid and the submandibular glands. Reverse transcriptase-polymerase chain reaction amplification of total RNA from parotid and submandibular glands confirmed the presence of all three hormone/growth factor mRNAs in both glands. The levels of insulin and IGF-I were higher in saliva from an animal model for autoimmune type 1 diabetes, the non-obese diabetic (NOD) mouse, than in a second inbred strain, BALB/c. In contrast, the IGF-II levels were decreased relative to the BALB/c strain. With the onset of diabetes in NOD mice, insulin levels declined, while IGF-I and IGF-II levels showed trends toward lower levels of these growth factors when compared with non-diabetic animals. These changes were reflected in the concentrations from parotid and submandibular gland cell lysates.
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PMID:Detection of insulin and insulin-like growth factors I and II in saliva and potential synthesis in the salivary glands of mice. Effects of type 1 diabetes mellitus. 776 95

A receptor tyrosine kinase (RTK), TIE (tyrosine kinase that contains immunoglobulin-like loops and epidermal growth factor [EGF] homology domains), is expressed in vascular endothelial and hematopoietic cells. We generated monoclonal antibodies (MoAbs) against the extracellular domain of TIE and a polyclonal antibody against the TIE carboxyterminus and used them to analyze expression of TIE in hematopoietic cells. Western blotting detected two forms of TIE protein with a molecular mass of 135 and 130 kD in hematopoietic and endothelial cells. Northern blotting analysis revealed that TIE was expressed preferentially in undifferentiated cell lines, especially when megakaryocytic, but not erythroid differentiation was induced. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that TIE was predominantly expressed in the human hematopoietic progenitor fraction, CD34+ cells. Fluorescence-activated cell sorting (FACS) showed that 42% of CD34+ and 17% of KIT-positive (KIT+) cells were TIE-positive (TIE+). The majority (81%) of the primitive hematopoietic stem cells, CD34+CD38- cells, were TIE+. Assays of progenitor cells and long-term culture-initiating cells (LTC-IC) showed that the TIE+ fraction contained more primitive cells than the TIE- fraction. Some TIE+ cells were in the CD34- fraction, which were CD19+ and CD20+ (B cells). These findings indicate that TIE has a unique spectrum of expression in primitive hematopoietic stem cells and B cells. Although its ligand has not been identified, TIE and its ligand may establish a novel regulatory pathway not only in early hematopoiesis, but also in the differentiation and/or proliferation of B cells.
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PMID:Predominant expression of a receptor tyrosine kinase, TIE, in hematopoietic stem cells and B cells. 854 81

It is widely accepted that polypeptide growth factors are involved in the growth and development of normal and neoplastic human prostate. It has been previously reported that epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) receptors are present in the human hyperplastic prostate tissue (BPH). To add information on the mechanism of action of EGF and transforming growth factor-alpha (TGF alpha), a peptide correlated to EGF, and the EGF receptor (EGF-R) in the human prostate, we studied the expression and cellular localization of messenger ribonucleic acid (RNA) encoding EGF, EGF-R, and TGF alpha in BPH tissue. Reverse transcriptase-PCR of total RNA extracted from BPH tissues documented the presence of specific transcripts for EGF, EGF-R, and TGF alpha. In situ hybridization with specific RNA probes synthesized from the respective complementary DNA demonstrated that EGF, EGF-R, and TGF alpha messenger RNAs were mainly localized in the epithelial cells. Immunprecipitation and Western blot analysis showed that BPH tissue contained the corresponding proteins, EGF and TGF alpha. Our findings provide additional support for the idea that EGF and TGF alpha may be considered specialized symbols in the language of cell-cell interactions and for the hypothesis that in the human prostate they seem to act in an autocrine fashion.
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PMID:Epidermal growth factor, epidermal growth factor receptor, and transforming growth factor-alpha in human hyperplastic prostate tissue: expression and cellular localization. 892 74

When the role of exogenous epidermal growth factor (EGF) during tooth eruption was first demonstrated it was strongly suggested that EGF was a natural regulator of eruption. Recent immunohistochemical studies have shown that EGF and EGF-receptors are localized in the dental follicle, alveolar bone and ameloblasts before and during the prefunctional stage of eruption. Localization of mRNA for EGF has also been successfully attempted in mouse incisors and molars. The purpose now was to study the temporal expression of EGF and EGF-receptor genes in the coronal aspect of the dental follicle. First molars from 2-, 5-, 9- and 11-day-old CD-1 mouse neonates were incubated in 1% trypsin for 1.5 h at 4 degrees C. Follicles were carefully separated from the coronal aspect of the molar and processed for RNA extraction. Reverse transcriptase-polymerase chain reaction was performed on each mRNA sample. EGF expression was detected at day 2, 5 and 9 in the coronal aspect of the follicle whereas EGF-receptor expression was found at day 9 only. These findings strongly suggest that cells of the dental follicle are the target of EGF at a specific stage of their development and therefore may have a very important role during eruption.
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PMID:Epidermal growth factor and epidermal growth factor-receptor expression in the mouse dental follicle during tooth eruption. 893 53

cDNA clones encoding human (h) Grb7 and a previously unknown protein with high homology to hGrb-IR and mGrb10 (where m indicates mouse) were found by screening expressed sequence tag data bases. hGrb7 mRNA expression is greatest in pancreas and restricted to a few other tissues. The second protein termed hGrb-IRbeta/Grb10 contains an intact PH domain and lacks the 80-residue mGrb10 insertion. Expression is greatest in pancreas and muscle but occurs in nearly all tissues. hGrb-IRbeta/Grb10 and hGrb-IR likely arise as alternative mRNA splicing products of a common gene. Reverse transcriptase-coupled polymerase chain reaction shows both mRNAs in muscle. In cells, Grb-IRbeta/Grb10 protein translocates from cytosol to membrane upon insulin stimulation, most likely due to direct interactions with the insulin receptor. These interactions are mediated by the SH2 domain and additional regions of the protein. Studies with mutated receptors and synthetic phosphopeptides show that the hGrb-IRbeta/Grb10 SH2 domain binds at least two sites in the insulin receptor: the kinase activation loop > the juxtamembrane site. hGrb-IRbeta/Grb10 also binds a 135-kDa phosphoprotein in unstimulated 3T3-L1 adipocytes; binding is reduced upon insulin stimulation. In addition, the c-Abl SH3 domain binds Grb-IR/Grb10, whereas Fyn, phosphatidylinositol 3-kinase p85, and Grb2 SH3 domains do not. The site of c-Abl SH3 domain interaction is highly conserved within the Grb-IR/Grb10/Grb7/Grb14 family. hGrb-IRbeta/Grb10 also binds platelet-derived growth factor and epidermal growth factor receptors, suggesting a broader role in the signaling pathways of numerous receptors. We conclude that hGrb-IRbeta/Grb10 is a widely expressed, PH and SH2 domain-containing, SH3 domain-binding protein that functions downstream from activated insulin and growth factor receptors.
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PMID:Human GRB-IRbeta/GRB10. Splice variants of an insulin and growth factor receptor-binding protein with PH and SH2 domains. 900 1

Nontransformed stromal colony-derived cell lines (CDCLs) consist of a pure stromal cell population that differentiates following a vascular smooth muscle cell repertoire, and whose in vivo counterpart is that of myoid cells found in adult and fetal human bone marrow cords. We studied the cytokine expression by reverse-transcriptase polymerase chain reaction (RT-PCR) from pooled fast-growing clones from 10 different bone marrow samples. RT-PCR indicated that 30 cytokines (out of 42 studied) were expressed by CDCLs (20 after medium renewal and hydrocortisone renewal, three after addition of interleukin I beta (IL-1 beta) and seven in only part of the CDCL layers examined). The cytokines expressed comprised mediators known to be involved in the maintenance of early and late hematopoiesis (IL-1 alpha and IL-beta, IL-6, IL-7, IL-8, IL-11 and IL-13; colony-stimulating factors, thrombopoietin, erythropoietin, stem cell factor, fit 3-ligand, hepatocyte cell growth factor, tumor necrosis factor alpha, leukemia inhibitory factor, transforming growth factors beta 1 and beta 3; and macrophage inflammatory protein 1 alpha), angiogenic factors (fibroblast growth factors 1 and 2, vascular endothelial growth factor) and mediators whose usual target (and source) is the connective tissue-forming cells (platelet-derived growth factor A, epidermal growth factor, transforming growth factors alpha and beta 2, oncostatin M and insulin-like growth factor 1), or neuronal cells (nerve growth factor). The cytokines not expressed were lymphokines (IL-2, IL-3, IL-4, IL-5, IL-9, IL-10, and IL-12 and interferon gamma) or mediators synthesized by macrophages (inhibin, activin, platelet-derived growth factor B, and IL-1 receptor antagonist). This study complements the description of the phenotype of the myoid cells, confirming that these cells are the marrow connective tissue-forming cells; moreover, this work suggests that stromal control of hematopoiesis is multifactorial and that myoid cells are involved in the control of marrow angiogenesis and innervation.
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PMID:The broad spectrum of cytokine gene expression by myoid cells from the human marrow microenvironment. 909 Jul 90

The effects of coculture and conditioned medium of rat hepatoma Reuber H-35 cells on the subsequent in vitro development and hatching of mouse 2-cell embryos were examined. The hatching of embryos obtained from CD-1 mice was accelerated by coculture with Reuber H-35 cells in the presence of 3 mg/ml BSA. The promoting effect on complete hatching from zona pellucida was evident even in cell-conditioned medium containing 60 micrograms/ml BSA. In the presence of 60 micrograms/ml BSA, more than 20% of embryos completely hatched, whereas none hatched in the control culture. The promoting activity was also found in both the M(r) < 10,000 and the M(r) > 10,000 subfractions of the conditioned medium separated by ultrafiltration. The cell number per blastocyst was increased to 1.1- to 1.3 times the control by culturing embryos from the 2-cell stage with the conditioned medium or its subfractions. The effective target of promoting factors for complete hatching was after the morula stage, and blastocysts hatched completely even when incubated in conditioned medium for 6 h. Inhibitors of DNA polymerase alpha, protein synthesis, and protein kinase partially reduced (40-90% inhibition) the promoting effect of the conditioned medium. On the other hand, protease inhibitors showed no effect. In a caseinolytic assay, protease activity was undetectable in the conditioned medium. Incubating the 125I-labeled proteins derived from the M(r) > 10,000 fraction with blastocysts revealed that at least 9 proteins with apparent molecular masses of 76, 60, 49, 38, 34, 31, 24, 22, and 18 kDa specifically bound to or accumulated in the embryos. Moreover, reverse-transcriptase polymerase chain reaction showed that Reuber H-35 cells expressed mRNAs for epidermal growth factor, transforming growth factors alpha and beta 1, and stem cell factor. These results indicated that embryonic development and the process of zona hatching was accelerated by factors synthesized by Reuber H-35 cells. This and other studies demonstrated that Reuber H-35 cells exert positive (later than 2-cell stage) and negative (at 2-cell stage) effects upon the development of mouse embryos at different embryonic stages. These factors will serve as valuable tools to clarify the proliferating and differentiating mechanisms of the preimplantation embryo.
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PMID:Rat hepatoma Reuber H-35 cells produce factors that promote the hatching of mouse embryos cultured in vitro. 909 89


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