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1.
Dexamethasone modulates the metabolism of type IV collagen and fibronectin in human basement-membrane-forming fibrosarcoma (HT-1080) cells. 总被引:1,自引:0,他引:1
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The effect of dexamethasone on the synthesis and degradation of type IV collagen was studied in human fibrosarcoma cells, HT-1080. A dexamethasone concentration as low as 0.1 microM markedly increased collagen synthesis in HT-1080 cells labelled with [14C]proline. The increase in type IV collagen synthesis was not specific, since total protein synthesis was also increased. Further studies indicated that part of the increase was due to an increase in the specific radioactivity of the intracellular proline pool, after dexamethasone treatment. In fact, with dexamethasone concentrations of 0.1-10 microM the relative collagen synthesis was decreased, indicating that synthesis of other protein was increased more than that of type IV collagen. This was also confirmed by measuring the relative amount of type IV collagen RNA by using recombinant plasmid cDNA specific for the human procollagen pro alpha l (IV) RNA. The results indicated that relative collagen synthesis and the relative amount of type IV collagen messenger RNA was decreased similarly, indicating that dexamethasone affected type IV collagen synthesis at the pre-translational level. The dexamethasone-induced effect on total protein and collagen synthesis was maximal after 12-24 h. Dexamethasone induced a marked accumulation of collagen into the cell layer, leading to diminished deposition of soluble collagen into the medium. Since bacterial-collagenase treatment of the cell layer drastically decreased the collagen content of the dexamethasone-treated cells, this indicates that dexamethasone caused an accumulation of collagen into the extracellular matrix of the cell layer. In contrast, the amount of fibronectin was markedly increased in the medium. Dexamethasone decreased the type IV collagen-degrading activity in HT-1080 cells. The HT-1080 cells contained glucocorticoid receptors, as demonstrated by two different methods: by a whole-cell binding assay and by using a cytosol-gel-filtration method. The number of specific binding sites was similar to that in human skin fibroblasts. In conclusion, glucocorticoids affect the metabolism of type IV collagen and fibronectin in HT-1080 cells, and, since these cells contain specific glucocorticoid receptors, the effects are apparently receptor-mediated. 相似文献
2.
Types I and IV collagenolytic and plasminogen activator activities in preovulatory ovarian follicles 总被引:1,自引:0,他引:1
A Palotie T Salo K K Vihko L Peltonen H Rajaniemi 《Journal of cellular biochemistry》1987,34(2):101-112
During ovulation, enzymatic degradation of the extracellular matrix occurs within and around the graafian follicles. In this study, the activities of several different proteolytic enzymes were measured in the culture media of follicles taken from pregnant mare serum gonadotropin (PMSG)-primed immature rats. At 52 h after PMSG, the follicles were cultured for 2 to 15 h in media with or without human chorionic gonadotropin (hCG). Type I collagenase activity in hCG-stimulated follicles gradually increased within 6 h to 3.3-fold above that of the controls. Relatively pure populations of granulosa cells produced type I collagenase to a similar extent. Likewise, type IV collagenase increased 3.8-fold by 6 h after exposure of the follicles to hCG. In contrast, plasminogen activator activity increased by 3.9-fold at 2 h after hCG, but was negligible at 4, 6, and 15 h after incubation. These results suggest that plasminogen activator may activate both type I and type IV collagenase in hCG-stimulated ovulatory follicles. 相似文献
3.
PD Dr. G. F. Jirikowski J. F. Ramalho-Ortigao K. W. Kesse F. E. Bloom 《Histochemistry and cell biology》1990,94(2):187-190
Summary We recently described a nonradioactive method for in situ hybridization with 5-bromo-2-deoxyuridine (BrdU) labelled oligonucleotide
probes. An antibody to BrdU and immunocytochemistry were used in order to detect the hybridization signal. We have now applied
this method to semithin Epon sections, in order to hybridize consecutive sections through single cells with different probes
and to stain them with antibodies to neuropeptides. It could be shown that Epon embedding preserves mRNA well. In the present
study we used a BrdU labelled synthetic oligonucleotide probe complementary to a fragment of the vasopressin precursor and
an antibody to Arg-vasopressin. Vasopressin mRNA was demonstrable in a fraction of the vasopressin immunoreactive neurons
in the magnocellular nuclei. In addition some of the magnocellular neurons showed either hybridization or vasopressin immunostaining
only, perhaps indicating different stages of synthetic and secretory activity.
The method described seems to be a valuable tool for studying synthetic activity in peptidergic neurons on a single cell level.
The method might also have potential for in situ hybridization on the electronmicroscopical level. 相似文献
4.
The cupro-zinc enzyme superoxide dismutase (SOD) undergoes an irreversible (oxidative) inactivation when exposed to its product, hydrogen peroxide (H2O2). Recent studies have shown that several oxidatively modified proteins (e.g., hemoglobin, albumin, catalase, etc.) are preferentially degraded by a novel proteolytic pathway in the red blood cell. We report that bovine SOD is oxidatively inactivated by exposure to H2O2, and that the inactivated enzyme is selectively degraded by proteolytic enzymes in cell-free extracts of bovine erythrocytes. For example, 95% inactivation of SOD by 1.5 mM H2O2 was accompanied by a 106 fold increase in the proteolytic susceptibility of the enzyme during (a subsequent) incubation with red cell extract. Both SOD inactivation and proteolytic susceptibility increased with H2O2 concentration and/or time of exposure to H2O2. Pre-incubation of red cell extracts with metal chelators, serine reagents, or sulfhydryl reagents inhibited the (subsequent) preferential degradation of H2O2-modified SOD. Furthermore, a slight inhibition of degradation was observed with the addition of ATP. We suggest that H2O2-inactivated SOD is recognized and preferentially degraded by the same. ATP-independent, metallo- serine- and sulfhydryl- proteinase pathway which degrades other oxidatively denatured red cell proteins. Related work in this laboratory suggests that this novel proteolytic pathway may actually consist of a 700 kDa enzyme complex of proteolytic activities. Mature red cells have no capacity for de novo protein synthesis but do have extremely high concentrations of SOD. Red cell SOD generates (and is, therefore, exposed to) H2O2 on a continuous basis, by dismutation of superoxide (from hemoglobin autooxidation and the interaction of hemoglobin with numerous xenobiotics).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
5.
Purification and characterization of a murine basement membrane collagen-degrading enzyme secreted by metastatic tumor cells 总被引:13,自引:0,他引:13
A type IV collagen-degrading enzyme activity secreted by a highly metastatic mouse tumor was purified by concanavalin A- and type IV collagen-agarose affinity chromatographies followed by gel filtration on Bio-Gel A-0.5 m. The apparent molecular weight of the enzyme was 160,000 but about 70,000 when Triton X-100 was added to the column buffer. The purified enzyme protein was resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis into two polypeptide chains of about 68,000 and 62,000 daltons. The enzyme activity could be increased by preincubation with trypsin and it is possible that the two chains represent latent and active enzyme forms. The enzyme activity was not reduced in the presence of dithiothreitol, it had a pH optimum of 7.6 and was inhibited by EDTA but not N-ethylmaleimide, phenylmethylsulfonyl fluoride, or Trasylol. The inhibition with EDTA was reversible. The pro-alpha 1(IV) and pro-alpha 2(IV) chains of the type IV procollagen substrate were both degraded at a similar rate to form two pairs of degradation fragments corresponding in molecular weights to about 70 and 30% of the original size chains. The presence of Triton X-100 increased slightly the activity of the enzyme and diminished the reduction of its activity upon freezing, indicating that the enzyme is a hydrophobic protein. 相似文献
6.
7.
J. Soinila A. Salo H. Uusitalo N. Yanaihara O. Häppölä 《Histochemistry and cell biology》1989,91(6):455-460
Summary Indirect immunofluorescence technique was used to study the occurrence and distribution of CGRP immunoreactivity in the submandibular gland of normal rats and after unilateral sensory and sympathetic denervations. In normal rats, CGRP-immunoreactive nerve fibers and nerve trunks were seen around or in close contact with interlobular salivary ducts as well as around small blood vessels of the gland. Occasionally, CGRP-immunoreactive nerve fibers were also detected between or around the acini of the gland.The submandibular ganglia contained CGRP-immunoreactive nerve fibers, but the ganglion cells were not immunoreactive for CGRP. The trigeminal ganglion contained a population of CGRP-immunoreactive, mainly small sized ganglion cells and nerve fibers distributed throughout the ganglion. Unilateral electrocoagulation of the trigeminal nerve caused a significant reduction in the number of immunoreactive nerve fibers in the gland, although some fibers still were present in the ipsilateral glandular tissue. Unilateral superior cervical ganglionectomy caused no detectable effect on the number of CGRP-immunoreactive nerve fibers in the gland.The present results suggest that the rat submandibular gland contains CGRP-immunoreactive nerve fibers both around blood vessels and in glandular secretory elements. Denervation experiments support the view that the majority, but perhaps not all of them originate from the trigeminal ganglion. 相似文献
8.
9.
Summary The microproblematicumPycnoporidium ? eomesozoicum
Flügel, 1972, from Upper Triassic reefs of the Alpine-Mediterranean region, Turkey Oman and Iran (originally interpreted as possible
alga) represents the type species of a new strophomenid brachiopod genus (Gosaukammerella n.g.). The genus is characterized by a very small, millimeter-sized plano-convex shell, whose ventral valve is attached to
the substratum (mainly sponges) by symmetrically arranged outgrowths developing from a pseudopunctate, lamellose foliated
shell wall and composed of densely spaced subparallel ‘tubes’ comparable with productide spines secreted by papillose extensions
of the mantle.Gosaukammerella seems to be the only reliable candidate for the existence of post-Paleozoic strophomenid (productid ?) brachiopods.
Gosaukammerella eomesozoica is restricted to possibly cryptic, shaded reef environments inhabited predominantly by sponges serving as substrates for
micromorphic brachiopods. 相似文献
10.
T. Schultz J. Soinila R. Tolonen O. Häppölä H. Uusitalo A. Salo 《The Histochemical journal》1994,26(7):563-570
Summary The distribution and origin of neuropeptide Y in the major salivary glands of the rat was studied by indirect immunofluorescence technique. Numerous nerve fibres immunoreactive for the peptide were seen in the parotid and sublingual glands. Most of the fibres were located around blood vessels and salivary acini. In the submandibular gland the number of immunoreactive nerve fibres around the acini was lower in comparison with that in the parotid and sublingual glands. Some immunoreactive nerve fibres were also found around or along intra- and interlobular ducts in all major salivary glands.A large number of the neuropeptide-containing neuronal cell bodies and nerve fibres were detected in the sympathetic superior cervical ganglion. Sympathetic postganglionic nerve trunks of this ganglion contained numerous immunoreactive nerve fibres as well. A subpopulation of the neuronal cell bodies in the submandibular ganglion were immunoreactive to neuropeptide Y.Both uni- and bilateral superior cervical ganglionectomies caused a significant decrease in the number of immunoreactive nerve fibres around the blood vessels in all the major salivary glands. However, these denervations did not affect the density of nerve fibres around the acini and ducts. On the contrary, unilateral parasympathetic denervation by sectioning the auriculotemporal nerve reduced the fibres around the secretory acini in the parotid gland remarkably, while only a minor reduction in the density of immunoreactive fibres associated with the blood vessels of the gland was detected. Unilateral electrocoagulation of the trigeminal nerve branches caused no detectable change in the density of immunoreactive nerve fibres in any of the major salivary glands.On the basis of the present findings it is concluded that neuropeptide Y-reactive nerve fibres present in all major salivary glands around the blood vessels seem to be mainly sympathetic, whereas those around the acini and ducts seems to be of parasympathetic origin. 相似文献