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1.
Biopsies from 74 cases of vitiligo were examined to study the reactions of marginal melanocytes. In 35 cases, the melanocytes at the edge of the patch appeared highly dendritic and large with marked arborization of the dendrites between the surrounding epidermal cells. These cells showed low pigmentation but a high enzyme activity which extended along the dendrites. The enzymes include tyrosinase/dopa oxidase, dopamine oxidase and noradrenaline activity, indicating that these cells have a biphasic melanogenic/adrenergic differentiation. This similarity between the dendritic melanocytes and the amelanotic melanoma cell line HT-18 is of interest. 相似文献
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Recent studies show that specification of some neural crest lineages occurs prior to or at the time of migration from the neural tube. We investigated what signaling events establish the melanocyte lineage, which has been shown to migrate from the trunk neural tube after the neuronal and glial lineages. Using in situ hybridization, we find that, although Wnts are expressed in the dorsal neural tube throughout the time when neural crest cells are migrating, the Wnt inhibitor cfrzb-1 is expressed in the neuronal and glial precursors and not in melanoblasts. This expression pattern suggests that Wnt signaling may be involved in specifying the melanocyte lineage. We further report that Wnt-3a-conditioned medium dramatically increases the number of pigment cells in quail neural crest cultures while decreasing the number of neurons and glial cells, without affecting proliferation. Conversely, BMP-4 is expressed in the dorsal neural tube throughout the time when neural crest cells are migrating, but is decreased coincident with the timing of melanoblast migration. This expression pattern suggests that BMP signaling may be involved in neural and glial cell differentiation or repression of melanogenesis. Purified BMP-4 reduces the number of pigment cells in culture while increasing the number of neurons and glial cells, also without affecting proliferation. Our data suggest that Wnt signaling specifies melanocytes at the expense of the neuronal and glial lineages, and further, that Wnt and BMP signaling have antagonistic functions in the specification of the trunk neural crest. 相似文献
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Gangliosides of normal and neoplastic human melanocytes 总被引:6,自引:0,他引:6
J M Carubia R K Yu L J Macala J M Kirkwood J M Varga 《Biochemical and biophysical research communications》1984,120(2):500-504
The major ganglioside component isolated from diploid human melanocytes is sialosyllactosylceramide (GM3 86-91% of total sialic acid). The corresponding disialo derivative (GD3) is found as a minor component (2-6% of total sialic acid) in the membranes of these cells. In human melanoma cells, grown in tissue culture, GD3 is the predominant ganglioside component (48-63% of total sialic acid). Withdrawal of TPA from the culture medium of normal melanocytes or addition of TPA to the medium of melanoma cells had no significant effect on GM3/GD3 ratios. We conclude that the difference between the composition of gangliosides is related to the normal vs transformed phenotypes of melanocytes. 相似文献
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Role of cellular antioxidants in metal-induced damage 总被引:23,自引:0,他引:23
M. Sugiyama 《Cell biology and toxicology》1994,10(1):1-22
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Expression and regulation of parathyroid hormone-related peptide in normal and malignant melanocytes
El Abdaimi K Papavasiliou V Goltzman D Kremer R 《American journal of physiology. Cell physiology》2000,279(4):C1230-C1238
We examined parathyroidhormone-related peptide (PTHrP) production and regulation in bothnormal human melanocytes and in a human amelanotic melanoma cell line(A375). Northern blot and immunocytochemical analysis demonstrated thatboth cultured A375 cells and normal human melanocytes express PTHrP,but A375 cells expressed much higher levels of the peptide. PTHrPsecretory rate increased at least 10-fold after treatment with 10%fetal bovine serum (100.2 ± 2.8 pmol/106 cells vs.basal <15 pmol/106 cells) in proliferating A375 cells butonly twofold in confluent cells. Treatment of A375 cells withincreasing concentrations of 1,25-dihydroxyvitamin D3[1,25-(OH)2D3] or its low-calcemic analogEB-1089 revealed that EB-1089 was 10-fold more potent than 1,25-(OH)2D3 on inhibition of both cellproliferation and PTHrP expression. Furthermore, inoculation of A375cells into the mammary fat pad of female severe combinedimmunodeficiency mice resulted in the development ofhypercalcemia and elevated concentrations of plasma immunoreactivePTHrP in the absence of detectable skeletal metastases. Our study,therefore, demonstrates a stepwise increase in PTHrP expression whencells progress from normal to malignant phenotype and suggests thatEB-1089 should be further evaluated as a therapeutic agent in human melanoma. 相似文献
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J R Vielkind K S Vogel 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》1989,2(1):44-52
Neural crest cells obtained from explanted neural tubes take up, express, and retain exogenous DNA applied by the CaPO4 co-precipitation method during their differentiation into melanocytes. High efficiencies of gene transfer were obtained with both supercoiled DNA and intact phage particles; linear DNA or DNA from the phage yielded very low efficiencies. There is some evidence that transferred gene expression is differentiation dependent. The system should be useful for studies concerned with the analysis of cell developmental genes and their regulatory elements. 相似文献
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Characterization of a normal avian cell protein related to the avian sarcoma virus transforming gene product. 总被引:74,自引:0,他引:74
In this paper, we identify and characterize both structurally and functionally a protein from normal uninfected avian cells that is antigenically related to the pp60src viral protein responsible for transformation by ASV. This protein was detected by immunoprecipitation of radiolabeled normal cell extracts with serum derived from marmosets bearing ASV-induced tumors. The normal avian cell protein, which has been detected in each of the four avian species tested (chicken, duck, quail and pheasant) is a phosphoprotein of 60,000 daltons. This protein is not related to any of the ASV structural proteins; however, its immunoprecipitation is prevented by preadsorption of the antiserum with cell extracts specifically containing pp60src. Peptide analyses by partial proteolysis using chymotrypsin resulted in a map of the normal cell protein that was very similar to that of pp60src. When Staphylococcus aureus V8 protease was used, however, one of the major cleavage products of the normal cell protein exhibited an altered migration with respect to the corresponding pp60src product. Tryptic phosphopeptide analyses demonstrated that phosphorylation of the normal cell protein was also different from that seen in pp60src. The expression of the normal cell protein did not seem to be affected by cellular growth conditions, maintaining a constant level which was approximately 30–50 fold lower than that of pp60src in infected cells. The normal cell protein appeared to be functionally dissimilar to pp60src lacking detectable protein kinase activity in the currently available assay system. 相似文献
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Significant RNA polymerase activity was demonstrated in isolated nuclei from mature avian erythrocytes. This activity was shown to have characteristics common to mammalian systems, including sensitivity to α-amanatin. A crude fraction of RNA polymerase was solubilized from these nuclei and characterized to provide further support for the existence of the enzyme in these cells. 相似文献
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This review focuses on natural and assisted prevention against lipid peroxidation in avian spermatozoa. The presence of high levels of n-6 polyunsaturated fatty acids (PUFAs) in the plasma membrane creates favorable conditions for the formation of peroxidative products, a major cause of membrane damage which may ultimately impair male fertility. However, a complex antioxidant system involving vitamin C, vitamin E and GSH is naturally present in avian semen. Coupled with a battery of enzymatic defenses (e.g., SOD, GSH-Px either Se- or non-Se-dependent), this system acts to prevent or restrict the formation and propagation of peroxides. The presence of specialized sites dedicated to prolonged sperm storage in avian females raises the question of durable protection of sperm membranes against peroxidation. Preliminary observations have revealed the presence of a specific antioxidant system at these sites in which vitamin C could exert a major role. From a practical standpoint, the extensive use of artificial insemination in poultry, along with the emergence in some species of workable techniques to cryopreserve spermatozoa, demand better control of peroxidation occurring in the plasma membrane of spermatozoa before or during storage. Dietary supplementation with vitamin E is effective in limiting lipid peroxidation of sperm plasma membranes, both in chickens and turkeys. In addition, organic Se with or without vitamin E stimulates Se-GSH-Px activity in seminal plasma. Preliminary observations in female chickens have also revealed the effectiveness of dietary supplementation with vitamin E, organic selenium or both to sustain fertility in aging flocks. 相似文献
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Melanoma growth stimulatory activity (MGSA) was originally described as an endogenous growth factor for human melanoma cells. To test the hypothesis that an MGSA autocrine loop is responsible for the partial freedom from growth control observed in nevocytes and melanoma cells, MGSA growth response and MGSA mRNA/protein levels were examined in these cells compared with normal melanocytes. As a single agent, or in combination with other factors, MGSA stimulated the growth of normal human epidermal melanocytes as well as other growth promoters for melanocytes. Nevocytes were not as responsive to exogenous MGSA as melanocytes. MGSA mRNA was minimal or not detected in cultured normal melanocytes, although the protein was present when the cells were cultured in the presence of serum/growth factors and absent when serum/growth factors were omitted. In contrast, MGSA mRNA was constitutively expressed in the absence of exogenous growth factors in cultures established from benign intradermal and dysplastic nevi and melanoma lesions in different stages of tumor progression. Nevus cultures contained immunoreactive MGSA protein in the presence of serum but were negative or only faintly positive in the absence of serum. Melanoma cell lines were positive for MGSA protein in both the presence and the absence of serum. Thus, continued expression of both MGSA mRNA and MGSA protein in the absence of exogenous hormones or serum factors may correlate with partial freedom from growth control exhibited by malignant melanocytes. 相似文献
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Duval C Smit NP Kolb AM Régnier M Pavel S Schmidt R 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2002,15(6):440-446
The pheo/eumelanin ratio of cultured normal human melanocytes is distinct from the ratio observed for the same cells in vivo where they are in close contact with keratinocytes. To study the possible involvement of keratinocytes in the control of melanogenesis, we compared quantitatively and qualitatively the melanin production in melanocyte mono-cultures, in melanocyte-keratinocyte co-cultures and in pigmented reconstructed epidermis. Pheomelanin and eumelanin contents were assessed by high-performance liquid chromatography with electrochemical and fluorometric detection of their specific degradation products and revealed striking differences in the presence of keratinocytes. In the absence of keratinocytes (melanocyte mono-cultures), we observed a very limited eumelanin production and a very high pheomelanin synthesis. The pheo/eumelanin ratio in mono-cultures could be slightly influenced by changing the composition of the culture medium, however, the very strong imbalance in favor of pheomelanin remained unchanged. An induction of eumelanin synthesis accompanied by an important reduction of pheomelanin formation was only observed in the presence of keratinocytes. The pheo/eumelanin ratio in melanocyte mono-culture dropped from 1043 down to about 25 in the presence of keratinocytes (co-cultures). The same observations were made when the melanocytes were integrated into a reconstructed human epidermis. Interestingly, under co-culture conditions resulting in only a partial contact between melanocytes and keratinocytes, the reduction of the pheo/eumelanin ratio were less pronounced. From these results we conclude that keratinocytes play an important role in the melanin production, affecting the melanogenic pathways. 相似文献
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Meenhard Herlyn Maria Laura Mancianti Jadranka Jambrosic Joseph B. Bolen Hilary Koprowski 《Experimental cell research》1988,179(2):322-331
Normal human melanocytes, unlike malignant melanoma cells, required at least three growth-promoting agents, i.e., phorbol ester for protein kinase C activation and the growth factors basic fibroblast growth factor (bFGF) and insulin, for growth in chemically defined W489 medium. Cell growth was further stimulated by addition of agents that increase intracellular levels of cyclic adenosine 3',5'-monophosphate (cAMP) to the medium. Among these agents, the pituitary hormones alpha-melanocyte-stimulating hormone (alpha-MSH) and follicle-stimulating hormone were the most potent, whereas bacterial toxins, including cholera, tetanus, and pertussis toxin and their subunits either were less mitogenic or gave variable results depending on the culture tested. Medium containing phorbol ester PMA, growth factors bFGF and insulin (or insulin-like growth factor-I), and synthetic alpha-MSH supported melanocyte growth for more than 5 months with doubling times between 5 and 8 days. Two copper-binding proteins, ceruloplasmin and tyrosinase, were mitogenic when added to medium and ceruloplasmic induced a long bi- to tripolar-shape of cells. Addition of 1 mM dibutyryl cAMP to the medium led to the formation of dendrites in all cells, with an average of 28 extensions per cell. Although cell growth was inhibited by dibutyryl cAMP, cells were not terminally differentiated and continued to proliferate. Dendritic melanocytes showed a 2.2-fold increase in activity of the tyrosine kinase pp60c-src. The induction of dendritic processes in melanocytes by dibutyryl cAMP or sodium butyrate was reversible and appears to reflect the expression of the mature melanocytic phenotype in situ. 相似文献
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The present study was conducted to evaluate the therapeutic effectiveness of chelating agents [glutathione, 2,3 dimercapto propane sulfonic acid (DMPS) and D-penicillamine (DPA)] in combination with antioxidant (sodium selenite) in beryllium induced toxicity in female rats. A bolus dose of 50mg/kg-beryllium nitrate was administered singly followed by chelation therapy with GSH, DMPS + Se and DPA + Se at various durations of 1,3 and 7 days respectively. Results revealed a significant fall in the glycogen content, whereas, a marginal fall in the protein was also observed. The enzymatic activity of alkaline phosphatase and adenosine triphosphatase was depleted; on the contrary, there was a significant rise in the acid phosphatase and glucose-6-phosphatase pattern. A rise in the hepatic lipid peroxidation activity is a direct indication of oxidative damage resulting in free radical generation. The distribution of the metal by atomic absorption spectrophotometry revealed an increased concentration of beryllium in liver and kidney, followed by lung and uterus. The relative ability of three chelating agents to act as antagonists, for acute beryllium poisoning, have been examined in liver, kidney, lungs and uterus. The appreciable change in the beryllium concentration in various organs is duration dependent during the entire period being highly significant at 7 days regimen. Biochemical and distribution studies reveal that DPA + Se was the most effective therapeutic agent followed by DMPS + Se and GSH. 相似文献
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Laminin-binding integrin alpha 7 beta 1: functional characterization and expression in normal and malignant melanocytes. 总被引:9,自引:2,他引:7
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R H Kramer M P Vu Y F Cheng D M Ramos R Timpl N Waleh 《Molecular biology of the cell》1991,2(10):805-817
A novel integrin, alpha 7 beta 1, that specifically binds with high affinity to laminin has been identified on melanoma cells. This complex was purified from both human and murine melanoma cells by laminin-affinity chromatography, and the alpha 7 subunit was recovered after gel electrophoresis. N-terminal amino acid sequence analysis of the alpha 7 subunit from both human and mouse cells verifies that this integrin is distinct from other alpha chains in the beta 1 family, although strikingly similar to the alpha 6 subunit. By using specific proteolytically derived fragments of laminin, it was determined that the alpha 7 beta 1 complex binds selectively to the E8 region, which represents part of the long arm of laminin. In contrast, the receptor failed to bind to the P1 fragment, which contains the intersection of the short arms of laminin. Although the alpha 7 beta 1 complex was commonly expressed in melanoma cells, this integrin was not detected in normal melanocytes, suggesting that alpha 7 expression may be associated with malignant transformation. These results establish the existence of a novel integrin that binds to the E8 domain of laminin and appears to mediate cell adhesion to this ligand. 相似文献
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Role of antioxidants in chronic fatigue syndrome in mice 总被引:11,自引:0,他引:11
The present study was carried out using mice model of chronic fatigue syndrome (CFS) in which mice were forced to swim everyday for 7 days for a 6 min session. There was a significant increase in despair behavior (immobility period) in saline treated mice on successive days. Treatment with potent antioxidants carvedilol (5 mg/kg, i.p.) and melatonin (10 mg/kg, i.p.) produced a significant reduction in immobility period. Similar results were observed with herbal products St. John's Wort (Hypericum perforatum L) (10 mg/kg, p.o.) and GS-02 (20 mg/kg, p.o.). Fluoxetine, a selective serotonin reuptake inhibitor produced a significant effect only on first and second day of its treatment. Biochemical analysis revealed that chronic swim test significantly increased lipid peroxidation and catalase levels in whole brains of mice. There was a decrease in the levels of super oxide dismutase (SOD) and glutathione reductase (GSH) in the brain. Administration of carvedilol, melatonin, GS-02 and St. John's Wort restored the levels of lipid peroxidation and glutathione. The enzymes SOD and catalase were also restored. Fluoxetine affected the biochemical variables not to the same extent as other treatments. The findings of the present study suggest that oxidative stress might play a significant role in the pathophysiology of CFS. Thus antioxidants and herbal products like St. Johns wort and GS-02 could be useful in the treatment of CFS. 相似文献