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)

Vitronectin is an adhesion protein present within the acrosomal cap region of human spermatozoa and is liberated during the acrosome reaction. The purpose of this study was to determine if vitronectin mRNA was synthesized in the male genital tract using the reverse transcriptase in-situ polymerase chain reaction (PCR) technique. Twelve genital tract tissues, which included six testes, one showing Sertoli cells only and one from a 3 year old boy, as well as sections from the prostate, seminal vesicles, and epididymis, were analysed for vitronectin transcripts. PCR-amplified vitronectin cDNA was detected in the seminiferous tubules of the four adult testes that showed normal spermatogenesis and localized to the spermatocytes and round spermatids. PCR-amplified vitronectin cDNA was not detected in the tissues of the prostate, epididymis, and seminal vesicles from the men whose testes did contain the message, nor in the testes with Sertoli cells only or that of the prepubertal boy. It is concluded that, in the male genital tract, vitronectin is transcribed exclusively in the germ cells at the spermatocyte and round spermatid stages. This demonstrates that the translated protein present in the spermatozoon is being produced in situ. Further study is needed to determine the role of this protein in the dynamics of sperm-oocyte interaction.
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PMID:PCR-amplified vitronectin mRNA localizes in situ to spermatocytes and round spermatids in the human testis. 856 71

To form distant metastases, tumour cells must stabilize adhesive interactions that prevent detachment at secondary sites. Primary receptor-ligand interactions alone may not maintain prolonged adhesive contacts without secondary events that lead to adhesion stabilization. Computerized imaging methods enable us to examine various substrates for: (i) the wall shear adhesion threshold (WSAT), a measure of the dynamic adhesive potential of tumour cells; (ii) the number of tumour cells that adhered; and (iii) the adhesion stabilization lag time (ASLT) or length of time required for tumour cells to stabilize adhesive contacts capable of withstanding high wall shear force (up to 100 dynes/cm2). The relative WSAT ratios found were: wheat germ agglutinin (WGA) > laminin > fibronectin > vitronectin > collagen I > collagen IV > von Willebrand factor (vWF) (the greater the shear rate the higher the adhesive potential). The relative stabilization ratios found were as follows: laminin < fibronectin < vitronectin < collagen IV < collagen I < vWF < WGA (shorter times correlate with greater stabilization potential). Stabilization data using fibronectin as a substrate correlated the best with metastatic potential. Using three melanoma lines of different metastatic potential semiquantitative reverse transcriptase-polymerase chain reaction (PCR) showed a two- to four-fold increase in alpha1, alpha3, alpha4, alpha5, alpha6, and ICAM-1 in the highly metastatic 70W cells compared to the MeWo and non-metastatic 3S5 melanoma cells. There were no differences in alphav, beta1 and beta3 levels among the three melanoma lines, and PCR products for alphaIIb, alpha2, CD36, or ICAM-2 were not detected. The 70W cells also had higher levels of alphax and beta2 (CD11/CD18 and p150 leukocyte antigen) than either the MeWo or 3S5 cells. The data indicate that melanoma cells exhibit differences in the adhesion properties under fluid shear and differences in the expression of adhesion components that correlate with their metastatic potential.
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PMID:Human melanoma integrins contribute to arrest and stabilization potential while flowing over extracellular matrix. 871 81

Vitronectin is a multifunctional protein present in serum and in extracellular matrices, but its localization has not been fully elucidated. In the present study, immunoblotting with anti-rat vitronectin antibody showed that rat testes contained vitronectin in both Triton-soluble and -insoluble fractions. Immunofluorescence microscopy demonstrated that this immunoreactivity was localized mainly in the interstitial Leydig cells. Occasionally vitronectin was shown in some spermatocytes and around blood vessels. Immunoelectron microscopy with nanogold probes showed that vitronectin was present in the cytoplasm of Leydig cells but not in the nucleus or in the mitochondria and probably not on the luminal side of the endoplasmic reticulum. In situ hybridization with synthetic oligonucleotides, however, showed that vitronectin mRNA was not present in Leydig cells, although a faint reaction was shown in spermatogonia and/or in early spermatocytes. This observation was supported by the results of reverse transcriptase polymerase chain reaction, which showed that vitronectin mRNA was not present in the Leydig cell fraction, whereas a band corresponding to vitronectin gene product was detected in the seminiferous tubule fraction. These results indicate that Leydig cells contain vitronectin but do not synthesize it. The source of vitronectin in Leydig cells seemed to be either spermatogenic cells or blood.
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PMID:Vitronectin in the cytoplasm of Leydig cells in the rat testis. 883 97

In this study we demonstrate that human endothelial cells (EC) synthesize mRNA for vitronectin by using techniques based on reverse transcriptase (RT) reaction and polymerase chain reaction (PCR). The identification of vitronectin mRNA, shown by sequence analysis of PCR-amplified RT product of RNA extracted from EC, clearly demonstrates that these cells synthesize mRNA for vitronection. We further investigated whether vitronectin in serum-free EC cultures regulates the net expression of the terminal complement pathway, measured as the terminal complement complex (TCC) bound to co-cultured agarose beads which activate the alternative pathway. Presence of polyclonal F(ab')2 anti-human vitronectin (VN) antibodies, regardless of concentration (10-80 micrograms/ml), significantly reduced the binding of monoclonal anti-C3c antibodies to co-cultured beads, whereas the binding of monoclonal anti-TCC antibodies was unaltered or significantly increased compared with controls. Despite some interexperimental variation in the results, addition of vitronectin (10-80 micrograms/ml) to the EC resulted in an inversely related pattern compared with experiments using anti-VN antibodies. The binding indices of anti-C3c are comparable to the controls. On the other hand, there is a steady concentration-dependent (10-80 micrograms of vitronectin added) reduction in binding of anti-TCC up to approximately 60%. The results indicate that vitronectin regulates the expression of synthezised and surface-bound TCC in serum-free EC cultures, comparable to previous findings in serum.
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PMID:Vitronectin modulates the expression of complement components of the terminal pathway synthesized by human umbilical vein endothelial cells in vitro. 892 Aug 5

Rat oligodendrocytes spontaneously activate complement (C) and lack the C inhibitor CD59. As a consequence, rat oligodendrocytes are susceptible to lysis by autologous C in vitro. Expression of C inhibitors on human oligodendrocytes in vitro and other human glia has yet to be well characterized. We have previously shown expression at the mRNA level of the membrane inhibitors CD59, decay-accelerating factor (DAF; CD55) and membrane cofactor protein (MCP; CD46) in human astrocytes. We here examine the expression of membrane and secreted C inhibitors by the oligodendrocyte cell line, HOG. HOG cells abundantly expressed CD59, assessed at protein and mRNA level, and expressed DAF and MCP, albeit at a lower level. Expression of all three inhibitors was enhanced by incubation with interferon-gamma or with phorbol ester (PMA). Complement receptor type 1 (CR1; CD35) was neither expressed constitutively nor induced by cytokines. HOG also constitutively secreted C1-inhibitor, S-protein and clusterin. Factor H was secreted only after stimulation with cytokines. C4b binding protein was expressed at a very low level and was detected only at the mRNA level by reverse transcriptase-polymerase chain reaction (RT-PCR). For comparison, astrocyte expression of CD59, DAF, MCP and CR1 was confirmed at the mRNA and protein levels. HOG did not activate C spontaneously, as judged by the lack of deposition of C fragments, and were not lysed by C even after inhibition of CD59 and DAF using specific monoclonal antibodies.
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PMID:Complement regulatory protein expression by a human oligodendrocyte cell line: cytokine regulation and comparison with astrocytes. 895 45

Pigmented villonodular synovitis (PVNS) and the histologically related lesion giant cell tumor of tendon sheath (GCTTS) are idiopathic, proliferative lesions that can induce osteolysis and formation of bone cysts. These lesions contain two predominant cell types: mononuclear polyhedral cells and multinucleated cells (MNCs). Previous studies demonstrated that the mononuclear cells exhibit phenotypic features consistent with derivation from a monocyte/macrophage lineage. The cell lineage of the MNCs and their relationship to osteoclasts are not known. To characterize the MNCs in these lesions and to establish the relationship of these MNCs to osteoclasts, histological sections from six cases of PVNS and two cases of GCTTS were studied. Mononuclear cells expressed CD14 and HLA-DR, in keeping with their relationship to cells of the monocyte/macrophage lineage. Characterization of the MNCs revealed features associated with an osteoclast phenotype. Seven of the eight specimens contained MNCs that were intensely tartrate-resistant acid phosphatase positive; approximately 5% of the mononuclear cells were tartrate-resistant acid phosphatase positive, and these tended to surround MNCs. MNCs in both lesions reacted strongly with the 23C6 monoclonal antibody that recognizes the alpha V beta 3 integrin (the vitronectin receptor), as did several mononuclear cells surrounding the MNCs. Most MNCs did not express CD14 or HLA-DR. Expression of receptors for calcitonin, a marker for osteoclasts, was detected on MNCs after incubation of sections with 125I-labeled salmon calcitonin and emulsion autoradiography. MNCs in four of six PVNS and two of two GCTTS samples demonstrated specific calcitonin binding. Expression of mRNA for calcitonin receptor was confirmed in all cases by reverse transcriptase polymerase chain reaction. These results demonstrate that MNCs in PVNS and GCTTS express phenotypic features of authentic osteoclasts and suggest that osteoclast-like multinucleated cells can arise in synovial soft tissues remote from bone.
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PMID:Multinucleated cells in pigmented villonodular synovitis and giant cell tumor of tendon sheath express features of osteoclasts. 909 94

The integrin beta5 subunit has only been found to form a heterodimer with subunit alphav which acts as a vitronectin receptor. Integrin alphavbeta5 has been implicated in cell migration and growth factor-induced angiogenesis. In the present study, a mouse liver cDNA library was screened using a human beta5 cDNA fragment obtained by reverse transcriptase PCR (RT-PCR). Three of the clones (MB5, MB15 and MB17) overlapped to give an open reading frame, called beta5A, which is homologous to the human beta5 subunit. The sequence of another clone (MB26), called beta5B, was identical with beta5A, except for a deletion of 29 bp near the 3' end of the open reading frame. The 29 bp deletion resulted in an open-reading-frame shift and a completely different C-terminal sequence in beta5B. beta5A and beta5B were shown, by RT-PCR, to be co-expressed in most mouse tissues tested, although beta5B mRNA was detected at much lower levels than beta5A. beta5A and beta5B mRNAs were also detected in the mouse monocytic cell line, J774, and in isolated mouse peritoneal macrophages. Adhesion of peritoneal macrophages has been shown to up-regulate the expression of both beta5A and beta5B mRNAs. The 29 bp sequence begins with a putative intron-splicing donor site (GTGAT...). A 3' fragment of the mouse integrin beta5 gene was cloned by PCR and sequenced showing that the 29 bp sequence was also immediately followed by an intron. Therefore, the 29 bp sequence was apparently expressed as part of the beta5A mRNA but was spliced out as part of the downstream intron in beta5B. Since the cytoplasmic domains of the integrin beta subunits are important in cytoskeleton attachment and signalling, the two alternatively spliced beta5 isoforms may have distinct roles in cell adhesion and other cellular functions.
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PMID:cDNA cloning reveals two mouse beta5 integrin transcripts distinct in cytoplasmic domains as a result of alternative splicing. 953 7

The plasmin activation system plays a key role in extracellular matrix degradation in many malignant tumors. Because no data are available on the involvement of the plasmin activation system in matrix degradation by thyroid carcinoma, the present study was performed using follicular thyroid carcinoma cell lines obtained from a primary tumor (FTC-133) and metastases (FTC-236 and FTC-238) of one patient. Matrix degradation by these cell lines was studied assessing the release of radioactivity from S35-methionine labeled extracellular matrix coated onto plastic. The involvement of constituents of the plasmin activation system as well as matrix metalloproteinases (MMPs), another class of proteolytic enzymes, which can be activated by plasmin, were assessed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and zymography. In the matrix degradation experiment, S35 release by FTC-133 was significantly higher than FTC-236 and FTC-238. S35 degradation could be inhibited by the plasmin inhibitor aprotinin and by anti-human urokinase-type plasminogen activator (uPA) antibody, indicating the involvement of the plasmin activation system. Matrix degradation could also be inhibited by the MMP inhibitor marimastat, thus demonstrating the involvement of MMPs in matrix degradation by these cell lines. Zymographic assays revealed activity of uPA in all cell lines. However, in contrast with FTC-236 and FTC-238, no plasminogen activator inhibitor (PAI) or PAI1 mRNA were found in FTC-133. Therefore, the differences in PAI activity as observed between the cell lines may originate from differences in PAI1 gene transcription. Differences in PAI1 expression did not affect the attachment of these cell lines to vitronectin. We conclude that the plasmin activation system is involved in extracellular matrix degradation by these metastatic follicular thyroid carcinoma cell lines. Differences in extracellular matrix degradation between the cell lines correspond with differences in PAI1 gene expression, indicating the significance of PAI1 in extracellular matrix degradation by metastatic follicular thyroid carcinoma.
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PMID:Degradation of extracellular matrix by metastatic follicular thyroid carcinoma cell lines: role of the plasmin activation system. 1052 70

Healing of venous leg ulcers depends on the adhesive interaction and formation of new vascular cells. Angiogenesis on the surface of angiogenic blood vessels requires the vascular integrin alphavbeta3 also known as the vitronectin receptor. Autologous platelet-derived wound healing factor (autologous PDWHF) has been described to regulate the wound healing process by forming granulation tissue in the early healing phase. Here we analysed the influence of autologous PDWHF on the expression of the alphavbeta3 integrin in tissue specimen of venous leg ulcers in comparison with placebo treated controls by using reverse transcriptase-polymerase chain reaction and immunohistochemistry. Our investigations provide evidence that mRNA and protein expression of alphavbeta3 were significantly increased in healing venous leg ulcers after 96 h treatment (p<0.05), whereas the total amount of alphavbeta3 mRNA and protein was not altered in placebo treated patients. In healing leg ulcers the alphavbeta3 integrin was predominantly localized around capillary vessels preferentially at sites of newly formed granulation tissue. Placebo controlled patients displayed no altered expression of the alphavbeta3 integrin in biopsy specimen. These findings suggest that topical autologous platelet-derived wound healing factor influences the process of angiogenesis/revascularization via alphavbeta3 integrin-expression hereby promoting granulation tissue formation in healing leg ulcers.
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PMID:Autologous platelet-derived wound healing factor promotes angiogenesis via alphavbeta3-integrin expression in chronic wounds. 1102 16

Severe combined immunodeficiency (SCID) mice were engrafted with rheumatoid arthritis (RA) synovium and evaluated to determine whether RA synovial morphology and function were maintained in the RA-SCID grafts. The four major components of RA synovitis, inflammation, immune reactivity, angiogenesis, and synovial hyperplasia persisted in RA-SCID grafts for 12 weeks. Retention of chronic inflammatory infiltrates was demonstrated by histological evaluation and by immunohistology for CD3, CD20, and CD68. Staining for CD68 also revealed that the grafts had undergone reorganization of the tissue, possibly as a result of fibroblast hyperplasia. Immune and inflammatory components were confirmed by the detection of human immunoglobulins and human interleukin-6 in serum samples obtained from grafted animals. Human blood vessels were detected by dense expression of CD31. Small vessels persistently expressed the vitronectin receptor, alpha v beta 3, a marker of angiogenesis. All vessels expressed VAP-1, a marker of activated endothelial cells. Finally, the grafts retained the ability to support immigration by human leukocytes, as demonstrated by the functional capacity to recruit adoptively transferred 5- (and -6)-carboxyfluorescein diacetate succinimidyl ester-labeled T cells. T cells entering the RA-SCID grafts became activated and produced interferon-gamma, as detected by reverse transcriptase-polymerase chain reaction analysis. These studies demonstrate that the RA-SCID model maintains many of the phenotypic and functional features of the inflamed RA synovium.
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PMID:Inflammation, immune reactivity, and angiogenesis in a severe combined immunodeficiency model of rheumatoid arthritis. 1178 29


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