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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cells in normal tendon are in a resting G0 state, performing maintenance functions. However, traumatic injury introduces growth factors such as platelet-derived growth factor and insulin-like growth factor from blood as well as activates endogenous growth factors. These factors stimulate migration and proliferation of tendon cells at the wound area. Tendon cells require growth-promoting factors to transit the cell cycle. To evaluate the contribution of endogenous growth factors in tendon, extracts of the epitenon and internal compartment of avian flexor tendon as well as medium of cultured cells from the epitenon (tendon surface cells) and internal tendon (tendon internal fibroblasts) were collected to assess their ability to stimulate DNA synthesis. Acid-ethanol extracts of tissues and medium were chromatographed on a P-30 molecular sieve column and assayed for mitogenic activity by quantitating [3H]thymidine incorporation into tendon cell DNA. The extract from the internal tendon compartment was more stimulatory for DNA synthesis than that from the epitenon, particularly when tested on tendon internal fibroblasts. However, conditioned medium fractions from surface epitenon cells stimulated DNA synthesis to a high degree on both tendon surface cells and tendon internal fibroblasts. Conditioned medium from tendon internal fibroblasts was also stimulatory. An anti-insulin-like growth factor-I antibody ablated most of the mitogenic activity present in both tissues and conditioned medium. The levels of acid-extractable insulin-like growth factor-I in tendon were determined by competitive radioimmunoassay as 1.48+/-0.05 ng/g tissue for the epitenon and 3.83+/-0.03 ng/g tissue for the internal compartment. Results of Western immunoblots of conditioned medium revealed insulin-like growth factor-I at the 7.5 kDa position. Cultured tendon surface cells and tendon internal fibroblasts as well as cells in intact flexor tendon expressed insulin-like growth factor-I mRNA detected by reverse transcriptase-polymerase chain reaction. In situ hybridization histochemistry positively identified insulin-like growth factor-I mRNA in tendons from 52-day-old chickens. Platelet-derived growth factor was not detected at the protein or message levels. Furthermore, tendon surface cells and tendon internal fibroblasts both expressed receptors for insulin-like growth factor-I detected by flow cytometry. These data suggest that tendon cells express insulin-like growth factor-I mRNA and synthesize insulin-like growth factor-I in both the epitenon and the internal compartment of tendon, which is present in an inactive form, most likely bound to insulin-like growth factor-binding proteins.
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PMID:Insulin-like growth factor-I is expressed by avian flexor tendon cells. 1105 90

Using sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) methods, we showed the expression of mRNA for growth hormone (GH) but not prolactin (PRL) in whole human skin (normal and basal cell carcinoma (BCC)). These RNAs for PRL and GH were below detectability in human epidermal keratinocytes and in human and hamster malignant melanocytes. This is in agreement with previous studies showing GH gene expression in dermal fibroblasts. GH peptide was not detected (by immunocytochemistry) in human skin specimens (normal and pathologic) in either dermal or epidermal compartments. The mRNA coding for the GH mediator insulin-like growth factor-1 (IGF-1) was detectable in whole skin and in malignant melanocytes. Therefore, in the present investigation of hormonal mediators of the cutaneous (epidermal) response to environmental stress, we have excluded the direct participation of PRL and GH in that reaction. Thus the analogy previously noted between the systemic (central) and skin responses to stress, as represented by cutaneous expression of hypothalamic-pituitary-adrenal axis components, does not extend to other pituitary hormones also involved in that response such as PRL and GH.
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PMID:Human skin expresses growth hormone but not the prolactin gene. 1112 49

The bronchial epithelium is a potential source of growth factors that could mediate airway fibrosis during the progression of diseases such as asthma and chronic bronchitis. We report that conditioned medium (CM) from normal human bronchial epithelial cells (NHBECs) contains mitogenic activity for human lung fibroblasts that is blocked by the epidermal growth factor receptor (EGF-R) tyrosine kinase inhibitor AG1478 and by neutralizing antibodies raised against heparin-binding epidermal growth factor-like growth factor (HB-EGF). Neutralizing antibodies against other EGF-R ligands (EGF and transforming growth factor-alpha) or other antibodies against growth factors (platelet-derived growth factors, insulin-like growth factor-1) had no affect on the mitogenic activity of NHBEC-CM. HB-EGF messenger RNA (mRNA) expression in NHBEC was detected by reverse transcriptase/polymerase chain reaction and Northern blot analysis. HB-EGF protein was detected by enzyme-linked immunosorbent assay. Vanadium pentoxide (V2O5), a fibrogenic metal associated with occupational asthma, caused a several-fold increase in HB-EGF mRNA expression and protein, whereas the inert metal titanium dioxide had no effect on HB-EGF expression. V2O5-induced HB-EGF mRNA expression was inhibited by the EGF-R tyrosine kinase inhibitor AG1478, the p38 mitogen-activated protein (MAP) kinase inhibitor SB203580, and the MAP kinase kinase inhibitor PD98059. Finally, HB-EGF induced the production of fibroblast growth factor (FGF)-2 by human lung fibroblasts and anti-FGF-2 antibody partially blocked the mitogenic activity of NHBEC-CM on fibroblasts. These data suggest that HB-EGF is a fibroblast mitogen produced by NHBECs and that induction of an FGF-2 autocrine loop in fibroblasts by HB-EGF accounts for part of this mitogenic activity.
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PMID:Vanadium stimulates human bronchial epithelial cells to produce heparin-binding epidermal growth factor-like growth factor: a mitogen for lung fibroblasts. 1115 45

The aim of the present study is to investigate the effect of insulin-like growth factor (IGF-I) on the development of cultured rat pre-antral follicles. Pre-antral follicles with a diameter between 140 and 160 microm are mechanically isolated from ovaries of 10-day-old rats and cultured in groups for 6 days in FSH and insulin-containing serum-free medium in the absence or presence of IGF-I at concentrations of 1, 10, and 100 ng/ml, respectively. DNA content of the follicles before and after culture is measured to evaluate whether a possible growth is due to proliferation of follicular cells and the ultrastructure of the cultured follicles is studied with transmission electron microscopy to evaluate the quality of follicles cultured under different conditions. Furthermore, reverse transcriptase polymerase chain reaction (RT-PCR) is used to assess the gene expression of IGF-I and type I IGF receptor in pre-antral follicles. When follicles were cultured in medium containing IGF-I at a concentration of 1 and 10 ng/ml, the increase in follicle diameter after a 6-day culture differs significantly from that in the absence of IGF-I. The ultrastructure of follicles cultured in IGF-I-containing medium is better sustained when compared to that of follicles cultured in the absence of IGF-I. Especially, theca cells, which are undergoing degeneration under controlled culture condition, demonstrate normal cellular ultrastructure with some characteristics of steroid-secreting cells in the presence of IGF-I. Moreover, in oocytes of follicles cultured in the presence of IGF-I, cortical granules are observed distributed along the ooplasma membrane whereas cortical granules are hardly present in follicles cultured without IGF-I. With RT-PCR, the presence of the mRNA of IGF-I and type I IGF receptor is demonstrated in both the somatic follicular cells and the oocytes. Taken together, these results suggest that IGF-I, in the presence of follicle-stimulating hormone (FSH), enhances rat pre-antral follicle development in vitro and supports the morphology of cultured pre-antral follicles. The stimulatory effect of exogenous IGF-I on the development of pre-antral follicle together with the gene expression of both IGF-I and type I IGF receptor in pre-antral follicles suggests the involvement of IGF-I in early folliculogenesis and its actions are likely mediated by the putative type I IGF receptor, via both endocrine and paracrine/autocrine pathways.
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PMID:Insulin-like growth factor-I (IGF-I) stimulates the development of cultured rat pre-antral follicles. 1117 Feb 70

We produced an immortalized colonic epithelial cell line, MCE301, using fetal mice transgenic for the temperature-sensitive simian virus 40 large T-antigen gene. MCE301 cells showed epithelial-like morphology and maintained tight connections with neighboring cells. The cells grew at a permissive temperature (33 degrees C), but the growth of the cells was significantly prevented at the nonpermissive temperature (39 degrees C). The cells expressed large T-antigen at 33 degrees C but not at 39 degrees C. MCE301 cells were not transformed, as judged by the absence of anchorage-independent growth in soft agar gel and lack of tumor formation in nude mice. Electron microscopic studies showed that the cells formed microvilli-like structures on the cell surface and junctional complexes such as tight junctions and desmosomes between the cells. The cells expressed cytosketal (acidic cytokeratins and actin), basement membrane (laminin and collagen type IV) and junctional complex proteins (ZO-1 and desmoplakin I + II), as judged by specific antibodies. Fetal bovine serum, epidermal growth factor, insulin-like growth factor and insulin significantly increased the cell growth at 33 degrees C. Moreover, MCE301 cells expressed colonic mucin Muc2 mRNA as demonstrated by reverse transcriptase-polymerase chain reaction, indicating that the cells originate from mucus-secreting cells. Alkaline phosphatase, a brush border-associated enzyme, was detected in the cells. Sodium butyrate (2 mM), an inducer of cellular differentiation, markedly elevated alkaline phosphatase activity. Thus, the present mouse colonic epithelial cell line MCE301 possessing these unique characteristics should provide a useful in vitro model of colonic epithelium.
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PMID:Establishment and characterization of a colonic epithelial cell line MCE301 from transgenic mice harboring temperature-sensitive simian virus 40 large T-antigen gene. 1123 98

Growth factor-induced activation of Akt (protein kinase B) is implicated in the proliferation of vascular smooth muscle cells (VSMC) in addition to antiapoptotic signaling. Although previous studies have documented increases in total Akt or Akt-1 activity in rodent VSMC, little is known about the regulation of Akt-2 or Akt-3 kinase activity in VSMC from any species. In the present study, reverse transcriptase-polymerase chain reaction revealed the expression of all three Akt isoforms in human aortic VSMC. In vitro kinase assays using immunoprecipitated Akt isoforms showed robust increases in Akt-3 activity after stimulation of human aortic VSMC with platelet-derived growth factor (PDGF), insulin, and insulin-like growth factor-1. In contrast, these growth factors produced modest and marginal increases in Akt-1 and Akt-2 kinase activity, respectively. Pretreatment of VSMC with a phosphoinositide-3kinase (PI-3K) inhibitor, LY294002, led to significant inhibition of growth factor(s)-induced increases in Akt-3 activity and DNA synthesis. The present findings provide the first direct evidence that the Akt-3 isoform is predominantly activated in human aortic VSMC. Moreover, these data suggest that PI-3K-dependent activation of Akt-3 may play a major role in VSMC proliferation.
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PMID:Enhanced stimulation of Akt-3/protein kinase B-gamma in human aortic smooth muscle cells. 1132 83

We studied expressions of various growth factors, their receptors, cell adhesion molecules and extracellular matrix components in Warthin's tumor of the salivary gland with immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). Various growth factors and their receptors, such as transforming growth factor-alpha (TGF-alpha), heparin-binding epidermal growth factor-like growth factor (HB-EGF), TGF-beta2, TG-beta3, insulin-like growth factor (IGF)-I and -II, vascular endothelial growth factor (VEGF), EGF receptor (EGFR), erb-B4, TGF-betaRI and II, Flt and Flk-1 and IGF receptor Ibeta, were found in epithelial cells and/or in some lymphoid cells. Fibronectin, laminin, collagen type IV and tenascin were found in stroma of the lymphoid tissue. Integrins such as alpha3beta1 and beta3, Thy-1, CD44 and VCAM-1 were also expressed in epithelial and/or lymphoid cells. These various proteins may interact and regulate the proliferation and cell attachment of both epithelial and lymphoid components in this unique tumor.
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PMID:Growth factors, extracellular matrix components and cell adhesion molecules Warthin's tumor. 1133 65

Human disuse muscle atrophy frequently accompanies orthopedic injury, arthritis, or bed rest, and recovery is often incomplete despite current rehabilitation programs. We have studied the vastus lateralis muscle in 12 patients with chronic disuse atrophy associated with chronic osteoarthritis of the hip both preoperatively and after total hip arthroplasty. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated an increase in the level of expression of myostatin, insulin-like growth factor-1 (IGF-1) and leukemia inhibitory factor (LIF) mRNAs compared to healthy control muscle. In all patients there was a significant correlation preoperatively between increasing myostatin mRNA expression and reduction in type 2A and 2B fiber area. In the 8 female patients there was a significant correlation between increased myostatin mRNA expression and the atrophy factor calculated for 2A and 2B fiber types preoperatively. We hypothesize that a complex interaction occurs between muscle growth regulating factors in the genesis of muscle wasting. Our results indicate that myostatin is a muscle-wasting factor contributing to type 2B and 2A atrophy. Other muscle growth factors, such as IGF-1 and LIF, may be upregulated in a counterregulatory fashion or may be involved in the fiber type switching seen in disuse muscle wasting.
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PMID:Myostatin, insulin-like growth factor-1, and leukemia inhibitory factor mRNAs are upregulated in chronic human disuse muscle atrophy. 1141 Sep 16

A cDNA encoding the porcine type 1 insulin-like growth factor receptor (IGF1R) was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). The sequence of a 4.2-kb product was determined and had an open reading frame, encoding 1367 amino acids with 98.1 and 95.2% sequence similarity to the human and rat IGF1R, respectively. In the comparison of RT-PCR derived IGF1R sequences from 12 unrelated pigs, 12 silent sequence variants were found.
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PMID:Cloning of porcine IGF1 receptor cDNA and detection of sequence polymorphisms using RT-PCR. 1173 11

Arteriogenic erectile dysfunction is associated with impairment of vascular perfusion to the erectile components of the penis. Animal studies have identified insulin-like growth factor (IGF-I) and vascular endothelial growth factor (VEGF) as penile angiogenic growth factors, but the role of these factors in humans is not well understood. We evaluated the ex vivo expression of IGF-I, VEGF, and their receptors (IGF-IR, Flt-1, and KDR) in human penile cavernosal smooth muscle cells (HCSMCs) to identify cellular and molecular pathways involved in the regulation of penile tissue vascularity. Primary culture was initiated with explants of human corpora cavernosa, and early passage (3-5) cells were used for these evaluations. Cultures were examined to verify the presence of smooth muscle cells and the absence of endothelial cell contamination. Specific monoclonal antibodies were used to localize growth factors and their receptors. To evaluate gene expression of VEGF, Flt-1, and KDR, total RNA was extracted from cavernosal cells and subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) using custom synthesized primers. To study the effect on cell proliferation, 10000 cells/well were exposed to varying concentrations of VEGF (0-50 ng/mL). At specified time periods the cells were trypsinized and counted. IGF-I and VEGF and their receptors were localized in the cultures, which were positive for the presence of smooth muscle cells and negative for endothelial cell contamination. RT-PCR evaluation revealed the expression of four splice variants of VEGF messenger RNA (VEGFs 121, 145, 165, and 189) and two of its receptors (Flt-1 and KDR). VEGF165 and VEGF121 were the most abundant forms of messenger RNA and Flt-1 appeared to be the most prominent receptor type in these cells. Exposure to VEGF elicited a twofold to threefold increase in the proliferation of HCSMCs. HCSMCs express both IGF-I and VEGF and their receptors, which may be important in the control of vascularity in human penile architecture.
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PMID:Ex vivo expression of angiogenic growth factors and their receptors in human penile cavernosal cells. 1251 88


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