Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A primary culture of mammalian parafollicular cells was established from rat thyroid glands in order to investigate the effects of serotonin and somatostatin on calcitonin secretion. Minced rat thyroid glands were dissociated with collagenase and cultured in a Ham's F-12K medium supplemented with calf serum (5%), insulin (1.3 X 10(-6) mol/l), hydrocortisone (10(-8) mol/l), transferrin (6.1 X 10(-9) mol/l), and glycyl-L-histidyl-L-lysin (2.5 X 10(-8) mol/l). Immunohistochemical peroxidase-antiperoxidase method revealed that the cultured parafollicular cells were immunopositive for human calcitonin, and electron microscopy demonstrated the existence of dense secretory granules in the cultured parafollicular cells. Addition of the Ca2+ to the culture medium stimulated calcitonin secretion from the cells dose-dependently as measured by radioimmunoassay. Pre-incubation of serotonin with the cells produced higher calcitonin levels in a dose-dependent manner. On the other hand, pre-incubation of somatostatin with the cells significantly inhibited calcitonin secretion.
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PMID:Effects of somatostatin and serotonin on calcitonin secretion from cultured rat parafollicular cells. 289 90

Hepatocyte cell suspensions obtained by collagenase perfusion method did not have transferrin (TF) receptors. However, after incubation at 37 degrees, they appeared to gain TF receptors, the number of which was the function of incubation time at 37 degrees. It is suggested that hepatocyte TF receptors are collagenase-sensitive. This study can explain previous observations that hepatocyte isolated with collagenase treatment of the tissue do not bind TF at 4 degrees but take up TF at 37 degrees.
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PMID:Recovery of transferrin receptors on hepatocytes membrane after collagenase perfusion. 300 61

The binding of 125I-transferrin to rat mammary cells isolated by collagenase and hyaluronidase digestion has been investigated. Surface binding was determined at 4 degrees C and total binding also at 4 degrees C but in the presence of 0.1% w/v saponin. KD values between 20 and 25 nM were obtained. Binding assays at 37 degrees C showed the internalisation of the receptor and the bound transferrin was occurring but also provided evidence for an impaired recycling of the receptors to the cell surface in the freshly isolated cells. No differences in total binding were observed in cells prepared at different stages of lactation with a mean value of 29 fmol transferrin bound/micrograms cellular DNA, equivalent to 180,000 receptors per cell.
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PMID:Transferrin receptor activity in rat mammary epithelial cells. 324 Mar 22

The content and distribution of transferrin receptors (Tf-R) in suspended adult rat hepatocytes were studied using 125I-protein A in combination with either a monoclonal (MRC OX-26) or a polyclonal antibody to Tf-R. Internal receptors were made accessible by permeabilization with digitonin. The number of Tf-R detected depended on the batch of collagenase used for liver perfusion. By using the monoclonal reagent in conjunction with the less damaging of two batches of the enzyme, 129,000 receptors were found per cell, with 47,000 (37%) of these on the surface. The polyclonal reagent yielded Tf-R numbers which were consistently higher than those obtained with MRC OX-26. This difference is interpreted as being due to the binding of several (on the average 5-6) molecules of polyclonal IgG per molecule of Tf-R. Remarkably, transferrin binding by Tf-R was not affected by this cluster of associated IgG and the overlayer of protein A. Parallel studies with 131I-transferrin in a simplified binding assay system yielded surface Tf-R estimates which, in most cases, were close to the values obtained with MRC OX-26. After prolonged exposure to collagenase, the ligand-binding capacity of Tf-R was more affected than its immunoreactivity. In preliminary studies, monensin (10 microM) produced a 32%-50% shift of Tf-R from the surface to the inside, whereas short-term incubation with epidermal growth factor (0.17 mM) brought about no clear-cut Tf-R redistribution.
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PMID:Quantification of rat hepatocyte transferrin receptors with poly- and monoclonal antibodies and protein A. 325 59

Corpora lutea were removed from regularly cycling dairy cows, dissociated with collagenase and cultured for 8 or 10 days in Ham's F-12 medium. In Exp. 1 treatment with insulin, or an insulin-transferrin-selenium combination (ITS), increased progesterone production from basal levels on Day 4 of culture to 234% (P less than 0.01) above controls on Day 10. LH alone increased progesterone production 45% above controls on Day 10 (P greater than 0.05). When LH was combined with insulin or ITS, progesterone production was stimulated to an average of 1802% (P less than 0.01) above controls on Day 10 of culture. Transferrin or selenium without insulin did not allow LH to stimulate progesterone synthesis. In Exp. II, LH alone or LH plus gentamicin or penicillin-streptomycin increased progesterone production from basal levels on Day 2 steadily to an average of 468% (P less than 0.01) above controls (no antibiotics) by Day 8 of culture. The addition of amphotericin-B, alone or in combination with the other antibiotics, inhibited all LH-stimulated progesterone synthesis, but did not affect basal progesterone levels. We conclude that insulin is essential for maximal steroidogenesis in a bovine luteal cell culture system, and that LH-stimulated progesterone production is inhibited in the presence of amphotericin-B, but is not inhibited by gentamicin or penicillin-streptomycin. The elimination of amphotericin-B, coupled with the addition of insulin to the cell culture system increased the responsiveness of the cells to LH. These culture conditions represent the first report in which LH increased total progesterone production for 10 days, maintaining luteal function in a chemically-defined culture system.
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PMID:Effects of antibiotics and medium supplements on steroidogenesis in cultured cow luteal cells. 327 87

Sperm maturation and storage occur in a unique milieu created in large part by the epididymal epithelium. To learn more about the interaction of the epididymal epithelial cell with both luminal and systemic environments, we now report on the preparation and characterization of epididymal epithelial cell plasma membranes. A preparation enriched for epididymal epithelial cell plasma membranes was isolated from collagenase-digested epididymal tubule fragments by hand-Dounce homogenization, differential centrifugation, and sucrose gradient centrifugation. The final membrane fraction was enriched 11-fold for the plasma membrane marker 5'-nucleotidase; 2.6-fold for the lysosomal marker acid phosphatase, and 3-fold for the Golgi marker thiamine pyrophosphatase. No enrichment was observed for mitochondrial or endoplasmic reticulum enzyme markers. Specific and saturable transferrin-binding activity was also detected in the final preparation. Electron microscopy revealed the presence of vesicles and sheets of membranes as well as an occasional Golgi apparatus. The plasma membrane fraction was used to generate monoclonal antibodies. Of 102 wells exhibiting growth, 12 were positive by immunofluorescent staining of frozen sections. Ten of these recognized determinants in epithelial cells, and 2 stained peritubular smooth muscle cells. Most of the epithelial cell-specific antibodies stained brush border alone or in combination with the basolateral plasma membrane. Three antibodies stained the Golgi apparatus. Most antibodies were specific for particular epididymal regions, 3 also recognized determinants in the kidney, and 1 stained residual bodies in the testis.
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PMID:Isolation and characterization of epididymal epithelial cell plasma membranes. 336 69

It is generally considered that in exocytosis the size of the secreting cells does not increase when the membranes of exocytosis vesicles fuse with the plasma membrane. As the factors involved in the regulation of this phenomenon are poorly understood, we thought it worthwhile to investigate the relationship between the plasma membrane surface area and secretory activity. Isolated rat hepatocytes were prepared by liver collagenase perfusion. Secretion of the plasma protein, transferrin (Tf) was detected at the single cell level with specific anti-rat transferrin antibodies using the reverse hemolytic plaque test. Hepatocyte surface and hemolytic ring surface areas were calculated from diameters of hepatocyte and hemolytic plaque measured after 5h of incubation. A highly significant correlation was established between the plaque-forming hepatocyte surface areas and the corresponding hemolytic surface areas. This result was confirmed using an automatic image analysis method. Two-month-old rats were compared to 4-month-old rats. We observed that the ratio of the quantity of transferrin secreted by hepatocytes to the hepatocyte surface area was constant for a given incubation time, whatever the size of the hepatocytes. These results suggest that the plasma membrane surface area of hepatocytes may constitute a limiting factor in Tf secretion.
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PMID:Correlation between plasma membrane surface area and transferrin secretion rate in isolated hepatocytes. 353 69

To investigate which cells of the liver express the receptor for transferrin, isolated rat liver cells produced by collagenase perfusion were fractionated by repeated differential centrifugation to produce hepatocytes (95% + 1%, mean +/- SD, n = 4) and nonparenchymal cells (97% + 1%, n = 3). Saturable, high-affinity binding of 125I-transferrin was demonstrated on intact cells at 4 degrees C, with average receptor numbers 20,900 +/- 3,160 (mean + SD, n = 4) for hepatocytes and 5,500 + 1,520 (n = 3) for nonparenchymal cells. Total cellular receptors measured in detergent permeabilized hepatocytes were 42,000 +/- 18,330 (mean +/- SD, n = 3) per cell and 14,760 +/- 7,120 (n = 3) per cell in the nonparenchymal fraction. Immunocytochemical demonstration of transferrin using antitransferrin, peroxidase antiperoxidase complex confirmed that both cell types bound transferrin. There was heterogeneity of the staining reaction since there was no detectable staining on 40% of hepatocytes and 60% of nonparenchymal cells. Microdensitometric analysis of the staining product corroborated the biochemical evidence that hepatocytes have, on average, more than three times more transferrin receptors than do nonparenchymal cells. These findings support the concept that the hepatocyte has a central role in the uptake and storage of transferrin iron.
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PMID:Heterogeneous distribution of transferrin receptors on parenchymal and nonparenchymal liver cells: biochemical and morphological evidence. 353 27

Rat ventral prostate epithelial cells were cultured in collagen gel after collagenase digestion. The primary cultures were mainly composed of single and spherical cells. After 10 days incubation in growth medium containing insulin, transferrin, and cholera toxin, there was a 3.8-fold increase in cell numbers, aggregates of which formed three-dimensional acinus-like structures. These structures consisted of one layer of cells surrounding the lumen. The cells were joined together with a junctional complex and had microvilli on the luminal surface and secretory vacuoles in the cytoplasm facing the lumen. The ultrastructural features of the cells were not altered by growth medium containing steroids. This culture system may prove to be very useful in elucidating proliferation, organization, and differentiation of prostatic epithelial cells in relation to the extracellular matrix and stromal cells.
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PMID:Primary culture of epithelial cells derived from the rat ventral prostate: formation of three-dimensional acinus-like structure in collagen gel. 356 46

Primary cultures of hepatocytes isolated by collagenase perfusion of adult rats were transformed by infection with adenovirus type 5 or transfection with adenovirus DNA. Total virion DNA or recombinant plasmid DNA containing the adenovirus E1A and E1B genes transformed hepatocytes at comparable frequencies. No foci of replicating hepatocytes were detected after transfection with a plasmid containing the E1A gene alone. The frequency of transformation by the adenovirus E1A and E1B genes was dependent on the composition of the culture medium. Transformation occurred at a low frequency when the transfected hepatocytes were maintained in a chemically defined medium (CDM), but the frequency was enhanced 8- to 10-fold when the cells were maintained in (i) serum-supplemented medium or (ii) CDM supplemented with epidermal growth factor. Cell lines derived from the adenovirus-transformed colonies of hepatocytes expressed adenovirus E1A and E1B RNAs. When hepatocytes were maintained in CDM supplemented with dimethyl sulfoxide and transfected with plasmids containing the E1A and E1B genes, it was possible to derive cell lines that retained the ability to express several liver-specific genes, including albumin, transferrin, hemopexin, and the third component of complement. The amount of albumin secreted per cell varied from 1 to 5 pg per cell per 24 h, and in one cell line it was below detectable levels by passage 9. Adenovirus-transformed hepatocytes were not tumorigenic when inoculated subcutaneously into neonatal syngeneic rats. We conclude that the adenovirus E1A and E1B genes are capable of transforming adult rat hepatocytes, a differentiated epithelial cell type.
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PMID:Transformation of differentiated rat hepatocytes with adenovirus and adenovirus DNA. 366 53


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