Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidermal cells produce various kinds of cytokines and express cell adhesion molecules. To analyze early events which induced in human epidermis by stimulation with various chemicals, we analyzed mRNA of cytokines expressed in epidermis in a human skin organ culture system. After painting haptens, primary irritants or vehicle control on human skin specimens sliced to 1 mm thickness and cut into approximately 5 x 5 mm blocks, the pieces were cultured in serum-free medium. After separating epidermis from dermis, total RNA was extracted and mRNA of cytokines was assessed by the reverse transcriptase-poly-merase chain reaction. Only haptens induced IL-1 beta mRNA at 1-3 hours. TNF-alpha mRNA was induced 9 hours after application of haptens and 1 hour after application of primary irritants. IL-1 alpha mRNA was not induced by either haptens or primary irritants. Thus, cytokine mRNA expression induced by haptens in epidermis differs from that induced by primary irritants.
J Dermatol 1998 Jul
PMID:Epidermal cytokine mRNA expression induced by hapten differs from that induced by primary irritant in human skin organ culture system. 971 73

Sebum production is regulated by the opposing effects of androgens and estrogens. The intracrine activity of steroid metabolizing enzymes is important in regulating sebum production because these enzymes can convert weak steroids from the serum into potent androgens and estrogens within the sebaceous gland (SG). 17Beta-hydroxysteroid dehydrogenase (17beta-HSD) interconverts weak and potent sex steroids via redox reactions. In this regard, it may function as a gatekeeping enzyme regulating the hormonal milieu of the SG. Six isozymes of 17beta-HSD have been identified that differ in their substrate preference and their preference to produce weak or potent sex steroids via oxidation or reduction, respectively. The goals of this study are: (i) to identify which isozyme (s) of 17beta-HSD is active in SG; (ii) to determine if its activity differs in facial skin compared with nonacne-prone skin that may account for the regional differences in sebum production; (iii) to compare the activity of 17beta-HSD in intact glands and in SG homogenates; and (iv) to determine if 13-cis retinoic acid inhibits 17beta-HSD activity. Human SG were assayed for 17beta-HSD activity using estrogens, androgens, and progestins as substrates. Oxidative activity of the type 2 isozyme predominated in all samples tested. Although transcripts for the types 1, 2, 3, and 4 isozymes were detected using reverse transcriptase-polymerase chain reaction, only mRNA for the predominant type 2 isozyme and the type 4 isozyme were detected in northern analysis. Greater reductive activity of 17beta-HSD was noted in SG from facial areas compared with nonacne-prone areas, suggesting an increased net production of potent androgens in facial areas. Oxidation was more predominant over reduction in intact SG compared with homogenized SG, thus supporting the hypothesis that 17beta-HSD protects against the effects of potent androgens in vivo. Activity of the type 2 17beta-HSD was not inhibited by 13-cis retinoic acid. In conclusion, SG possess the cellular machinery needed to transcribe the genes for the type 1-4 isozymes of 17beta-HSD. At the protein level, however, oxidative activity of the type 2 isozyme predominates, suggesting that 17beta-HSD isozyme activity may be translationally regulated.
J Invest Dermatol 1998 Sep
PMID:Oxidative activity of the type 2 isozyme of 17beta-hydroxysteroid dehydrogenase (17beta-HSD) predominates in human sebaceous glands. 974 Feb 29

Proopiomelanocortin (POMC) is a precursor polypeptide for various bioactive peptides, including adrenocorticotropic hormone, alpha-, beta-, and gamma-melanotropin, beta-endorphin, and beta-lipotropin. Although the classical source of POMC is the pituitary, various studies indicate the expression of POMC in several nonpituitary tissues. In this study, in situ hybridization with anti-sense cRNA riboprobe was used to show expression of POMC mRNA in human epidermis and cultured human epidermal cells (melanocytes and keratinocytes). POMC mRNA was amplified by reverse transcriptase-polymerase chain reaction using anti-sense and sense primers designed from Exons 2 and 3 of POMC gene. A approximately 300 bp product was present in normal human skin, grafted human skin, and cultured normal human melanocytes and keratinocytes. By Southern analysis this product was hybridized specifically to the POMC cDNA. Sequence analysis of the reverse transcriptase polymerase chain reaction product from tissues or cells showed 85% homology to POMC cDNA from human, bovine, pig, and monkey sources. This suggests the existence of a putative isoform or variant of POMC mRNA in human epidermis.
J Invest Dermatol 1998 Sep
PMID:Identification and sequencing of a putative variant of proopiomelanocortin in human epidermis and epidermal cells in culture. 1020 40

Expression of HLA class I molecules is essential for the recognition of tumor cells by CD8+ T cells. In this study, 48 bioptic samples of 42 patients in all stages of melanoma were investigated after short-time cultivation of tumor cells. To confirm melanocytic origin of cultured cells, samples were screened for mRNA expression of melanoma markers gp100, tyrosinase, MAGE-3, MelanA, and MUC18 by reverse transcriptase-polymerase chain reaction. Surface expression of specific HLA-A and -B allospecificities on melanoma cells were analyzed with a standard microcytotoxicity assay after stimulation with interferon (IFN)-alpha and compared with the background found in peripheral blood mononuclear cells from the corresponding patients. Immunohistochemistry and flow cytometry confirmed specific losses in cases where the appropriate monoclonal antibodies were available. The level of expression of HLA-I, HLA-II, and intercellular adhesion molecule 1 antigens on melanoma cells cultured in the presence or absence of IFN-alpha and IFN-gamma was determined cytofluorometrically. All cell cultures tested were found to be positive for one or more melanocytic markers by reverse transcriptase-polymerase chain reaction. The specific HLA-I alleles on the cultured cells were detectable in 45 of 48 samples. In 11 cases a specific loss of one HLA-I allele was observed (2 x A2, B7, B8, B18, 4XB44, B47, B49). Ten of these samples were derived from locoregional lymphnode metastases or from distant metastatic tumors. Only one sample from a primary melanoma showed a specific loss of HLA-I (B47). IFN-alpha upregulated expression of HLA-I up to 4-fold. IFN-gamma enhanced the appearance of HLA-II up to 35-fold and the expression of intercellular adhesion molecule 1 up to 40-fold. Selective loss of HLA-I allospecificities might be a major step in tumor progression.
J Invest Dermatol 1998 Sep
PMID:Higher frequency of selective losses of HLA-A and -B allospecificities in metastasis than in primary melanoma lesions. 974 Feb 47

Parathyroid hormone-related protein (PTHrP) is strongly expressed in the epidermis and has been implicated in the regulation of growth and differentiation of keratinocytes. PTHrP has N-terminal sequence homology with parathyroid hormone (PTH) and binds to the type I PTH/PTHrP receptor, but earlier reports suggest that keratinocytes do not possess this cell surface receptor. In order to determine which PTHrP mRNA isoforms are expressed by keratinocytes and whether the type I receptor mRNA is present, we designed specific primers for reverse transcriptase-polymerase chain reaction. The interaction of PTHrP with other promoters of keratinocyte differentiation is unclear. In particular, 1,25(OH)2D3 is also fundamental in calcium homeostasis and induces changes in intracellular calcium. We therefore investigated the effect of 1,25(OH)2D3 on PTHrP mRNA expression and protein production in cultured human keratinocytes. Cells were incubated for 3 days at concentrations of 1.25(OH)2D3 of 10(-10)-10(-6) mol/L. PTHrP in culture supernatant, measured by two site immunoradiometric assay, was 915 +/- 98 PTHrP fmol/mg of cell layer protein in untreated cultures decreasing to 570 +/- 113 with 10(-8) mol/L and 402 +/- 24 with 10(-6) mol/L 1,25(OH)2D3 (mean +/- SEM, P < 0.01, n = 6). Transcripts for all three PTHrP isoforms (139, 141 and 173 amino acids) were detectable in keratinocyte mRNA. Corresponding to the decrease in PTHrP protein we demonstrated a reduction in all three PTHrP mRNA transcripts after 3 days' incubation with 1,25(OH)2D3 over a concentration range 10(-10)-10(-6) mol/L. Repeated studies failed to detect type I PTH/PTHrP receptor mRNA in human keratinocytes, either in control cultures or in the presence of 1,25(OH)2D3. We have shown that keratinocytes produce abundant PTHrP and that this is modulated by 1,25(OH)2D3, suggesting a physiological role. Further studies are required to investigate the relative expression of PTHrP isoforms, their role in keratinocyte signalling and the receptors involved.
Br J Dermatol 1998 Jun
PMID:Human keratinocytes express transcripts for three isoforms of parathyroid hormone-related protein (PTHrP), but not for the parathyroid hormone/PTHrP receptor: effects of 1,25(OH)2 vitamin D3. 974 54

In a study initially designed to evaluate reinnervation of human cutaneous wounds using an antibody to the neuroneal marker protein gene product (PGP) 9.5, we observed marked immunostaining of cells with morphologic features of fibroblasts in the wounds. PGP 9.5 has recently been shown to be an important enzyme in the highly conserved ubiquitin system of proteolysis. Because the ubiquitin system is known to play an important role in regulating the cell cycle, the presence of PGP 9.5 in cells at a wound site was of considerable interest. Our objectives were to clarify the time frame for the appearance of PGP 9.5 and ubiquitin in wounds, to verify that PGP 9.5 is produced by wound fibroblasts, and to evaluate a potential role for these proteins in the tissue repair process. Standard incisional human wounds were stained with antibodies specific for PGP 9.5 and ubiquitin. At 7 d, stellate cells with morphologic features of fibroblasts stained for PGP 9.5, whereas earlier wounds were generally negative. In 14 and 21 d incised wounds and in chronic granulation tissue from nonhealing ulcers there was strong cellular staining for PGP 9.5 and for ubiquitin. These stellate cells also showed expression of mRNA for PGP 9.5 by reverse transcriptase-polymerase chain reaction in situ hybridization. PGP 9.5 was detected in cultured fibroblasts both by reverse transcriptase-polymerase chain reaction and by northern blot analysis. Confocal microscopy showed colocalization of antibodies to PGP 9.5 and prolyl-4-hydroxylase (a fibroblast marker) as well as colocalization of PGP 9.5 and the platelet derived growth factor beta receptor. We conclude that ubiquitin and PGP 9.5 were expressed by fibroblasts during the granulation tissue and remodeling phases wound healing. The mRNA for PGP 9.5 was demonstrated in stellate cells in chronic wounds and in fibroblasts in culture. The appearance of these degradative proteins in later wounds suggests a downregulation function in the wound healing response.
J Invest Dermatol 1998 Oct
PMID:Protein gene product 9.5 is expressed by fibroblasts in human cutaneous wounds. 976 34

Lipodermatosclerosis refers to skin induration of the lower extremities and is associated with patients preceding venous ulcerations. To better understand the pathogenesis of ulcer formation we investigated the expression of matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in lipodermatosclerosis. By preparing biopsies from healthy skin and liposclerotic lesions, MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were analyzed by using reverse transcriptase-polymerase chain reaction, western blot, zymography, hydrolysis of [3H]labeled collagens, and immunohistochemistry. Our investigations provide evidence that mRNA and protein expression of MMP-1, MMP-2, and TIMP-1 were significantly increased in lipodermatosclerosis, whereas the total amount of MMP-9 and TIMP-2 mRNA and protein was not altered. Western blot of liposclerotic lesions revealed an inactive proMMP-1-TIMP-1 complex, whereas MMP-2 was prominent as an active 66 kDa band. Increased proteolytic activity of MMP-2 could be proven in lesional in comparison with healthy skin by zymography and [3H] collagen degradation. Increased diffuse staining was found for MMP-1 in the epidermis and dermis in comparison with controls. In lipodermatosclerosis, MMP-2 was predominantly localized in the basal and suprabasal layers of the epidermis, in perivascular regions, and in the reticular part of the dermis. Furthermore, MMP-2 was imbalanced by locally reduced expression of TIMP-2 in the basement membrane zone of lesional skin. Our findings indicate lipodermatosclerosis to be characterized by elevated matrix turnover.
J Invest Dermatol 1998 Nov
PMID:Lipodermatosclerosis is characterized by elevated expression and activation of matrix metalloproteinases: implications for venous ulcer formation. 1038 52

Mutations of the gene encoding myosin V can produce a dilute or silvery hair color and various neurologic defects in mice and patients with Griscelli syndrome, leading to speculations that the myosin V motor protein plays a critical role in transporting melanosomes within melanocytes and neurosecretory vesicles within neurons. Therefore, we investigated the in vitro expression of myosin V in cultured normal human melanocytes, keratinocytes, and dermal fibroblasts using reverse transcriptase-polymerase chain reaction and northern blot analysis. Subcellular distribution of myosin V and proximity to actin bundles and melanosomes were determined by double indirect immunofluorescence labeling and immunogold electron microscopy. In all studied cells myosin V is expressed and treatment of melanocytes with the cyclic AMP-inducer 3-isobutyl-1-methylxanthine causes an induction of the myosin V message. In all cells myosin V colocalizes with actin bundles, concentrating in the subcortical cell zone. In the melanocyte it is closely associated with melanosomes. Quantitative analysis of myosin V labeling in melanocytes reveals a significantly higher (p < 0.005) presence of myosin V in the periphery of dendrites. These results suggest that myosin V is important in melanosome transport in human melanocytes. Possible roles in the other skin cells remain to be elucidated.
J Invest Dermatol 1998 Nov
PMID:Myosin V colocalizes with melanosomes and subcortical actin bundles not associated with stress fibers in human epidermal melanocytes. 980 47

We analyzed changes of growth and apoptotic cell death in human hair follicles. In anagen hair follicles, terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate-biotin nick labeling-positive cells were observed in the keratogenous zone of the upper bulb matrix, the inner root sheath, and the companion layer of the outer root sheath. DNA ladder formation was also detected in anagen hair follicles. In catagen hair follicles, the lower bulb matrix cells around the dermal papilla and the outer layer cells of the outer root sheath became strongly positive, showing that apoptosis in catagen hair is distinct from that in anagen hair. We also confirmed the mRNA expression of four caspases (caspase-1, caspase-3, caspase-4, and caspase-7) in anagen hair follicles by reverse transcriptase-polymerase chain reaction and in situ hybridization. When human anagen hair follicles were cultured in the presence of transforming growth factor-beta or tumor necrosis factor-alpha in the serum-free medium, transforming growth factor-beta but not tumor necrosis factor-alpha induced catagen-like morphologic changes, which were indistinguishable from normal catagen hair follicles. Tumor necrosis factor-alpha, however, strongly inhibited the elongation of the hair shaft in a dose-dependent manner, accompanied by abnormal morphology and increased cell death in the bulb matrix cells. Our results suggest that apoptosis in hair follicles involves two different types. One is related to the terminal differentiation of follicular epithelial cells in anagen hair. The other occurs as a major driving force to eliminate the distinct portion of epithelial components in catagen hair. Furthermore, this study strongly indicates that the transforming growth factor-beta pathway is involved in the induction of catagen phase in human hair cycle.
J Invest Dermatol 1998 Dec
PMID:Analysis of apoptotic cell death in human hair follicles in vivo and in vitro. 985 1

Although the precise underlying pathomechanisms of psoriasis have not been fully elucidated, previous reports suggest that T helper 1-type cytokines are critically involved in the pathogenesis of this disease. Interleukin-12 (IL-12), a heterodimeric cytokine, has been suggested to play a major role in the development of T helper 1 cell responses. In this study, the presence of IL-12 mRNA and protein was investigated in normal human skin as well as nonlesional and lesional psoriatic skin. Messenger RNA levels were determined in biopsy specimens by a standard and a nested reverse transcriptase-polymerase chain reaction method. Additionally, IL-12 protein expression was analyzed in situ by immunohistochemistry using an antibody recognizing IL-12 p70. Whereas specific transcripts for IL-12 p35 were reproducibly detected without any significant differences in all samples, enhanced IL-12 p40 mRNA signals were only found in lesional psoriatic skin as compared with normal and nonlesional psoriatic skin. Furthermore, immunoreactivity for IL-12 p70 was markedly increased in the psoriatic skin lesions and was predominantly expressed on mononuclear cells in the dermis. In conclusion, our data suggest a critical role for IL-12 in promoting and maintaining T cell activation and inducing T helper 1-type cytokines such as interferon-gamma in psoriasis. We speculate that IL-12 might be a key cytokine in the pathogenesis of psoriasis.
J Invest Dermatol 1998 Dec
PMID:Expression of interleukin-12 is increased in psoriatic skin. 985 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>