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)

Cultured BALB/c epidermal Langerhans cells express high levels of the costimulatory molecule B7 on their surfaces relative to levels expressed on fresh Langerhans cells. Quantitation of relative amounts of B7 mRNA in fresh epidermal cells and cultured epidermal cells following amplification of mRNA signals via reverse transcriptase-polymerase chain reaction, hybridization of PCR products with radiolabeled internal oligonucleotide probes, resolution of hybrids in non-denaturing polyacrylamide gels, and detection by autoradiography revealed dramatically (approximately one thousandfold) higher levels of B7 mRNA in cultured epidermal cells (10-40% I-A+) as compared with fresh epidermal cells (1-4% I-A+). Levels of B7 mRNA in cultured epidermal cells were also substantially greater than those detected in a reference B lymphoma cell line (CH-1). Analysis of B7 mRNA expression in subpopulations of cultured epidermal cells demonstrated that essentially all of the B7 mRNA was present in Langerhans cells; cells bearing I-A and CD45 antigens. Cultured keratinocytes did not contain appreciable amounts of B7 mRNA. These results are consistent with previous data regarding surface expression of B7 by cLC and also demonstrate that fLC are essentially devoid of B7 mRNA and surface protein.
J Invest Dermatol 1993 Dec
PMID:Regulation of expression of B7 by murine Langerhans cells: a direct relationship between B7 mRNA levels and the level of surface expression of B7 by Langerhans cells. 750 29

In human epidermis, expression of CD1a is confined to Langerhans cells (LC), whereas CD1c expression has been observed in dendritic cells of the dermis, as well as the epidermis. In transfected fibroblasts, expression of CD1c at the cell surface appears to exclude expression of either CD1b or CD1a, despite continued transcription of the latter genes. In order to determine whether this mechanism might be operative in human skin, we have compared the expression of CD1a and CD1c on the surface of dermal and epidermal dendritic cells to their expression at the level of mRNA using a combination of dual-label immunofluorescence microscopy, northern blot hybridization, and reverse transcriptase-polymerase chain reaction (RT-PCR). By both immunofluorescence and Northern blotting, CD1c expression was observed in both dermal and epidermal cells, whereas expression of CD1a was confined largely to the epidermis. Moreover, as shown by immunomagnetic bead selection and RT-PCR, CD1a and CD1c were both expressed on epidermal LC, but were absent from other epidermal cell types. These results argue against cell surface exclusion as a mechanism for selective expression of CD1c in human dermis.
J Dermatol Sci 1993 Dec
PMID:CD1 gene expression in human skin. 751 Sep 98

The c-kit ligand is expressed on tissue-anchored stromal cells. It plays an important role in the development of c-kit-bearing cells, such as haematopoietic cells, germ cells, mast cells and melanocytes. In the present study, we used the reverse transcriptase-mediated polymerase chain reaction (PCR) technique to investigate whether human keratinocytes are able to express c-kit ligand mRNA. Two sets of primers were designed to distinguish two types of c-kit ligand mRNA (full-length type and spliced type). One set was used to amplify an 882-bp DNA fragment from the full-length type, and a 798-bp DNA fragment from the spliced type. Another set was used to amplify a 375-bp DNA fragment from the full-length type only. A cDNA fragment corresponding to the full-length type mRNA was amplified from a cDNA preparation of cultured human keratinocytes as well as from epidermis obtained by the suction blister technique. This result indicates the spontaneous transcription of full-length type mRNA of the c-kit ligand in human keratinocytes.
Arch Dermatol Res 1994
PMID:Expression of c-kit ligand in human keratinocytes. 752 Feb 25

Three different intercellular adhesion molecules (ICAMs) have been identified acting as ligand for counter-receptor leukocyte-function-associated antigen-1 (LFA-1) (CD11a/CD18). We have recently shown that ICAM-1 (CD54) is present on cultured human epidermal Langerhans cells but not on freshly isolated Langerhans cells, and that this molecule participates in the generation of an antigen-specific T-cell response. ICAM-2 (CD102) was not involved because this molecule is expressed by neither fresh nor cultured Langerhans cells. In this study, the presence of ICAM-3 (CD50) on Langerhans cells was examined. Flow cytofluorometric analysis demonstrated that ICAM-3 is strongly displayed by fresh Langerhans cells, and daily determinations showed that the level of this trypsin-resistant molecule remained nearly unchanged during in vitro culture for up to 4 d, indicating that Langerhans cells constitutively express this molecule. Analysis of RNA extracted from purified cultured Langerhans cells by means of reverse transcriptase-polymerase chain reaction demonstrated the presence of mRNA specific for ICAM-3. Antigen-specific T-cell responses triggered by Langerhans cells were dose-dependently inhibited by anti-ICAM-3 if the antibody was added within the first 16 h of T-cell stimulation. Simultaneous addition of anti-ICAM-1 and anti-ICAM-3 synergistically inhibited T-cell responses, although a total block was never achieved. Pretreatment of Langerhans cells with anti-ICAM-3 resulted in a reduced T-cell response, whereas pretreatment of T cells did not. These results suggest that ICAM-3 on Langerhans cells, like ICAM-1, is functionally involved in the initiation of antigen-specific activation of T cells, but the expression of these two ICAMs on Langerhans cells is differently regulated.
J Invest Dermatol 1995 Jun
PMID:Intercellular adhesion molecule-3 (CD50) on human epidermal Langerhans cells participates in T-cell activation. 753 71

The effects of staphylococcal enterotoxin B (SEB), a Staphylococcus aureus-derived bacterial superantigen, on expression of intercellular adhesion molecule-1 (ICAM-1) were examined in cultured normal and transformed (DJM-1 cells) human keratinocytes by flow cytometry, confocal microscopy, digital image processing, and reverse transcriptase-polymerase chain reaction. SEB significantly upregulated ICAM-1 expression in the interferon-gamma (IFN-gamma)-pretreated, HLA-DR-positive normal keratinocytes and DJM-1 cells in a dose-dependent manner, but not in the untreated, HLA-DR-negative cells. Other toxins such as diphtheria and pertussis toxins did not have the effect. The distribution of SEB and HLA-DR molecules was identical on the IFN-gamma-treated, HLA-DR-positive DJM-1 cells by confocal microscopy. Digital image processing analysis demonstrated that SEB induced a transient increase of intracellular calcium concentration only in the IFN-gamma-treated DJM-1 cells. Pretreatment of the IFN-gamma-treated DJM-1 cells with anti-major histocompatibility complex class II monoclonal antibody completely blocked the effect of SEB. Furthermore, ICAM-1 mRNA was detected in the IFN-gamma-pretreated, SEB-exposed normal keratinocytes by reverse transcriptase-polymerase chain reaction. Our results demonstrate that SEB binds to keratinocytes, presumably via major histocompatibility complex class II molecules such as HLA-DR, triggers calcium mobilization, and induces the synthesis of ICAM-1 molecules. We speculate that, in various cutaneous disorders, SEB penetrates the epidermis and interacts with HLA-DR-positive keratinocytes to upregulate ICAM-1 expression, thus modulating the course of the inflammatory process.
J Invest Dermatol 1995 Oct
PMID:Staphylococcal enterotoxin B upregulates expression of ICAM-1 molecules on IFN-gamma-treated keratinocytes and keratinocyte cell lines. 756 Nov 55

Neurofibromin enhances the inactivation of protooncogene p21ras and has been suggested to function as a regulator of cell growth and differentiation. In normal skin, neurofibromin is particularly abundant in the basal keratinocytes of epidermis. The present study utilized antibodies raised against two synthetic peptides corresponding to different regions of neurofibromin. One of the antibodies recognized all forms of neurofibromin and the other was specific for type II neurofibromin. The following specimens were analyzed for neurofibromin immunoreactivity: 1) skin of apparently healthy volunteers, 2) active lesions of 15 psoriatic patients, 3) apparently healthy skin of the same patients at the time of the active phase of the disease, and 4) the previously lesional areas after anti-psoriatic treatment of the same patients. The presence of neurofibromin mRNA in normal epidermis and in keratinocytes cultured from normal skin was demonstrated by reverse transcriptase-polymerase chain reaction or by Northern hybridization. In marked contrast to normal epidermis, active psoriatic lesions were characterized by a weak immunosignal for types I and II neurofibromin in the basal cell layer of the epidermis. Previously lesional, clinically healed areas displayed variable, yet clearly detectable, expression of neurofibromin. Our results demonstrate that the epidermis of psoriatic lesions displays reduced immunostaining for type I and II neurofibromins compared to normal epidermis, and that neurofibromin immunoreactivity is partially restored concomitant with clinical healing of the lesions. The question whether the changes in neurofibromin expression in psoriasis are causal or consequential with respect to the pathogenesis of psoriasis remains to be elucidated.
J Invest Dermatol 1995 Nov
PMID:Lesional psoriatic epidermis displays reduced neurofibromin immunoreactivity. 759 40

We investigated the responses of normal and scleroderma fibroblasts to various growth factors, especially transforming growth factor-beta 1 (TGF-beta 1). The effects of various growth factors on [3H]thymidine incorporation in normal and scleroderma fibroblasts were examined. [125I]-labeled platelet-derived growth factor (PDGF)-BB binding in scleroderma and normal fibroblasts was examined both in the presence and absence of TGF-beta 1 (1 ng/ml). Cytoplasmic protein was isolated and analyzed by Western blotting. Total RNA from fibroblasts was also isolated and analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) using specific primer sets. Mitogenic responses to TGF-beta 1 (0.33-1 ng/ml) in seven scleroderma fibroblast strains were significantly greater than those in normal controls. [125I]-PDGF-BB binding to scleroderma fibroblasts was increased after TGF-beta 1 stimulation. The increased response to TGF-beta 1 was shown to be mediated through PDGF-like protein induction; TGF-beta 1-treated scleroderma fibroblasts produced greater amounts of 36-kD PDGF-like protein, which was reported previously as connective tissue growth factor (CTGF), than did TGF-beta 1-treated normal fibroblasts. TGF-beta 1 treatment also upregulated PDGF-alpha receptor expression in scleroderma fibroblasts but not in normal dermal fibroblasts. mRNA expression of CTGF and PDGF-alpha receptor was correlated with the above protein expression. These observations suggest that the increased growth response to TGF-beta 1 in scleroderma fibroblasts is mediated through the induction of CTGF and PDGF-alpha receptor.
J Invest Dermatol 1995 Jul
PMID:Growth regulation in scleroderma fibroblasts: increased response to transforming growth factor-beta 1. 761 66

A third human desmocollin, designated DSC3, was identified in foreskin epidermis by reverse transcriptase-polymerase chain reaction (PCR) using degenerate desmocollin primers. cDNA clones covering the entire coding sequence of the longer DSC3 splice variant were isolated and sequenced. Sequence comparisons indicated that this new desmocollin showed greater homology (67% amino acid identity) with the original human desmocollin (now designated DSC2) than with DSC1 (52% amino acid identity) although it had a unique potential cell adhesion recognition site (YAS). DSC3 was assigned to chromosome 18 by PCR analysis of rodent-human somatic cell hybrids, where it appears to be closely linked to all the other desmosomal cadherin genes. The expression of the three human desmocollins was examined in foreskin epidermis by in situ hybridization with 3'-untranslated riboprobes and by immunofluorescence with isoform-specific anti-peptide antibodies. DSC1 was present in the upper spinous/granular layers but not in the basal/lower spinous layers of the tissue. DSC2 and DSC3 were present in most of the living layers of the epidermis. DSC1 was not detected in any of the nonkeratinizing human epithelia examined (buccal mucosa, cervix, esophagus), indicating that it is specific for the keratinizing epithelium of the epidermis. However, all these internal epithelia expressed DSC2 and DSC3, and both were present in most of the living layers of the tissues including the basal layers.
J Invest Dermatol 1995 Sep
PMID:The desmocollins of human foreskin epidermis: identification and chromosomal assignment of a third gene and expression patterns of the three isoforms. 766 6

Human papillomavirus type 11 (HPV-11), produced from the athymic mouse xenograft system, was shown to infect cultured neonatal human foreskin keratinocytes and the HaCaT keratinocyte cell line in vitro. Infection was documented by the appearance of HPV-11-specific spliced mRNA, detected by reverse transcriptase-polymerase chain reaction. Purified HPV-11 virions at concentrations of approximately 10(7) particles/ml could successfully evoke infection in this system. Infection was completely abrogated by preincubation of the HPV-11 inoculum with mouse anti-HPV-11 monoclonal antibodies, experimentally immunized animal sera, or sera of human patients with HPV infection. Concurrent detection of cellular mRNA for the beta-actin gene, also by reverse transcriptase-polymerase chain reaction, provided an internal control confirming RNA recovery and successful reverse transcriptase-polymerase chain reaction. Using this approach, it was possible to determine semiquantitative titers for test solutions of HPV-11-neutralizing antibodies. The in vitro system for HPV-11 infectivity and neutralization may be useful in the study of the immune response to HPV-11 infection or immunization in patients.
J Invest Dermatol 1995 Sep
PMID:Titration of HPV-11 infectivity and antibody neutralization can be measured in vitro. 766 26

As dendritic antigen-presenting cells in skin and mucous membranes, Langerhans cells (LC) are found in areas at risk of inoculation by the human immunodeficiency virus (HIV). LC have been reported as targets for HIV-1. The aim of the present study was to investigate whether LC can be experimentally infected by HIV provided by a cell-free infection system. A cell-free suspensions was prepared from viral particles provided by chronically infected cell lines (U937 or H9 cells) by low-speed centrifugation followed by 0.45-microns filtration. LC-enriched epidermal cell (EC) suspensions with no CD3+ cells (assessed by flow cytometry and electron microscopy) and uninfected U937 cells (cell-free infection system control) were infected with two isolates (HTL VIII-B and RF). The infectiousness of the cell-free virus fluids was controlled on U937 cells where proviral DNA was amplified (gag, pol, and env gene sequences by the polymerase chain reaction, PCR) and release of virus particles into the supernatant was controlled either by measure of the reverse transcriptase (RT) activity or detection of viral RNA amplified by RT-PCR for the gag gene sequences). Proviral DNA (gag gene sequences) was found in LC-enriched epidermal cellular DNA from day 4 post-infection with isolate HTL VIII-B and from day 7 with isolate RF. Although the RT activity did not reach a significantly high level, viral RNA was found in the supernatant of LC-enriched EC cultures at the same time as proviral DNA was detected in LC.(ABSTRACT TRUNCATED AT 250 WORDS)
Arch Dermatol Res 1994
PMID:Detection of HIV-specific DNA sequences in epidermal Langerhans cells infected in vitro by means of a cell-free system. 772 34


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