摘要:

AbstractThe effects of cachectin/tumor necrosis factor (TNF) on growth and differentiation of 3T3‐L1 cells were examined. This fibroblastic cell line can be induced to differentiate into a mature cell type having the biochemical and morphological characteristics of normal adipocytes. At various stages of growth and differentiation, 3T3‐L1 cells were exposed to 2.5 × 10−16to 2.5 × 10−8M (4.2 fg/ml to 420 ng/ml = ca. 1.2 × 10−14to 1.2 × 10−6U/ml) recombinant human cachectin/TNF for 24 hr, after which cytotoxicity or differentiation was evaluated. During log‐phase cell growth, cachectin/TNF had no significant effect on cell viability, and the preadipocytic cells were also resistant to the cytotoxic effect of cachectin/TNF at the contact‐inhibited confluent stage. However, when cachectin/TNF was added to the cells during induced differentiation, only 20% of the cells survived. After differentiation into adipocytes, cells regained their resistance to cachectin/TNF‐induced cytotoxicity. Cachectin/TNF also markedly affected the differentiation of 3T3‐L1 cells into adipocytes. When cells in the confluent phase of growth were exposed to cachectin/TNF for 24 hr, their subsequent hormone‐induced differentiation to adipocytes was inhibited. Like cachectin/TNF, IL‐1 also induces suppression of lipoprotein lipase and enhances lipolysis in differentiated 3T3‐L1 adipocytes; however, in contrast to cachectin/TNF, IL‐1 had no effect on the viability or differentiation of pre‐adipocyte 3T3‐L1 cells. These results indicate that the cytotoxic action of cachectin/TNF varies in the same cell type depending on the stage of growth or differentiation. The results also imply that cachectin/TNF may play a normal role in controlling the differentiation of certain types of cells i

ISSN:0021-9541    

DOI:10.1002/jcp.1041380102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractProliferation of human skin fibroblasts was stimulated significantly by the presence of L‐ascorbic acid 2‐phosphate (Asc 2‐P). The presence of Asc 2‐P (0.1–1.0 mM) in the culture medium for 3 weeks enhanced the relative rate of collagen synthesis to total protein synthesis 2‐fold as well as cell growth 4‐fold. Coexistence of L‐azetidine 2‐carboxylic acid (AzC), an inhibitor of collagen synthesis, attenuated both effects of Asc 2‐P in a dose‐dependent manner. Supplementation of the medium with Asc 2‐P also accelerated procollagen processing to collagen and deposition of collagen in the cell layer. Among the acidic glycosaminoglycans (GAG), another major component of extracellular matrix (ECM), deposition of sulfated forms was increased by the additive. Electron microscopic observations showed multilayered, rough endoplasmic reticulum‐rich cells surrounded by dense ECM. These results indicate that Asc 2‐P is useful in culture systems as a long‐acting vitamin C derivative and also that it promotes reorganization of a three‐dimensional tissuelike substance from skin fibroblasts in culture by stimulating collagen

ISSN:0021-9541    

DOI:10.1002/jcp.1041380103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have studied the effect of increased intracellular levels of cyclic AMP on the growth response to platelet‐derived growth factor (PDGF) of human foreskin fibroblasts in culture. It was found that forskolin, a potent stimulator of adenylate cyclase activity, inhibits the stimulatory effect of PDGF on3H‐thymidine incorporation with a dose dependence similar to that observed with regard to cyclic AMP formation. A time‐course study indicated that forskolin has no effect on ongoing DNA synthesis but affects events in the prereplicative phase. The cell‐cycle block induced by forskolin was found to be reversible; after removal of the drug, DMA synthesis was initiated after a lag period, similar to that of the prereplicative phase of control cells. Forskolin had no effect on PDGF binding, receptor autophosphorylation, or c‐fosmRNA expression. However, a reduction in PDGF‐induced c‐mycmRNA expression was observed in cultures given forskolin. Forskolin was also found to have a marked stimulatory effect on the expression of interferon‐β2mRNA expression. However, we were unable to demonstrate that the growth‐inhibitory effect of forskolin is mediated by interferon‐β. In conclusion, an increase in cAMP levels leads to a reversible inhibition of PDGF‐induced DNA synthesis in human fibroblasts, which may be related to an inhibition

ISSN:0021-9541    

DOI:10.1002/jcp.1041380104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWe recently identified two types of mast cell colonies derived from murine peritoneal cells: type 1 and type 2. Type 1 mast cell colonies consisted of berberine sulfate(+)‐ safranin(+) connective tissue‐type mast cells (CTMC) and were derived from mature CTMC in the heaviest fraction obtained by Percoll density gradient centrifugation. In contrast, type 2 mast cell colonies consisted of alcian blue(+)‐ berberine sulfate(−)‐ safranin(−) mucosal mast cells (MMC) and were derived from immature progenitors in low density fractions. We replated a total of 60 type 1 and 60 type 2 mast cell colonies and examined their capability for producing secondary colonies. Although all of the primary colonies yielded secondary colonies, the replating efficiencies of individual colonies varied over a wide range.Cumulative distributions of secondary colonies from both type 1 and type 2 primary colonies could be fitted well by gamma distributions obtained by computer simulation. These findings are in agreement with the stochastic model for CTMC‐ and MMC proliferation. Cytological analyses of secondary colonies from primary type 1 colonies revealed heterogeneous distributions of alcian blue(+)‐ safranin(−)‐ berberine sulfate(−) mast cells, suggesting that transdifferentiation from mature CTMC to safranin(−)‐ berberine sulfate(−) mast cells is also govern

ISSN:0021-9541    

DOI:10.1002/jcp.1041380105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractDexamethasone inhibited the basal and EGF‐stimulated DNA synthesis of adult rat hepatocytes in primary culture. The inhibition was glucocorticoid‐specific: It was shown by dexamethasone and hydrocortisone, but not by progesterone, testosterone, or estradiol; and was counteracted by the glucocorticoid antagonist RU‐38486 in a concentration‐dependent manner. Dexamethasone acted by decreasing the rate of entry into S‐phase (kG1/S), while cell cycle parameters were unaffected. The steroid was able to decrease the kG1/Sseveralfold even when added more than 20 hr after EGF, half‐maximal effect occurring 11 hr after the addition of dexamethasone. Densily populated areas were much more sensitive to the inhibition by dexamethasone than sparsely populated areas within the same culture dish: A moderate (10 nM) concentration of dexamethasone nearly abolished the DNA synthesis in densily populated areas of hepatocyte cultures with only marginal effect on sparsely popu

ISSN:0021-9541    

DOI:10.1002/jcp.1041380106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have studied the tissue distribution of interleukin (IL) and hemopoietic colony‐stimulating factor (CSF) transcripts in mice by S1‐nuclease protection analysis. Accumulation of several of these mRNAs in response to intravenous injection of lipopolysaccharide (IPS) appears to occur in a tissue‐specific fashion. IL‐1α transcripts accumulate in spleen and lung; IL‐6 transcripts accumulate in kidney, heart, and spleen; granulocyte‐macrophage‐CSF transcripts accumulate in lung and heart; and granulocyte‐CSF transcripts accumulate in heart. Three distinct patterns of in vivo mRNA accumulation were detected: (1) silent—interleukins 2–5 showed no transcripts in either LPS‐treated or untreated animals; (2) induced—IL‐1α, IL‐6, granulocyte‐macrophage (GM)‐CSF, and G‐CSF transcripts were increased in abundance in LPS‐injected mice; and (3) constitutive—M‐CSF transcripts were found in similar amounts in both untreated and treated mice

ISSN:0021-9541    

DOI:10.1002/jcp.1041380107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractIn human melanoma cells one can detect two discrete DNA replication intermediates, 10‐kb DNA intermediates and Okakzaki fragments. Both intermediates are seen when cells are rapidly growing in medium supplemented with fetal calf serum. When the medium is supplemented with newborn calf serum, one can detect Okakzaki fragments but not 10‐kb DNA intermediates. In contrast we do not detect changes in the replicon sizes in the two me

ISSN:0021-9541    

DOI:10.1002/jcp.1041380108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have studied superoxide dismutase (SOD) levels in the X‐REF‐23 rat embryo fibroblast cell line. X‐REF‐23 is an immortal cell line that maintains a nontransformed phenotype throughout its known lifespan. Low‐passage X‐REF‐23 cells undergo spontaneous differentiation into muscle and adipose cells, while high‐passage X‐REF‐23 cells undergo little or no differentiation. SOD activities were measured in subclones of X‐REF‐23, which differentiate into muscle (AMC subclone) or adipose (AMB‐J) cells, as well as the parental nondifferentiating X‐REF‐23 cells. Total SOD activity increased in all three cell lines with time in culture. Cu‐ZnSOD was induced in the AMB‐J and the X‐REF‐23 cells with time in culture, whereas the AMC cells showed no induction. MnSOD activity was induced during the time period in which differentiation occurred in the two differentiating clones. In contrast, MnSOD was not induced in this time period in the nondifferentiating X‐REF‐23 cell line. However, MnSOD activity was induced in the latter cell line at a much later time. Levels of immunoreactive MnSOD correlated quite well with MnSOD activity in all three cell lines. The nondifferentiating X‐REF‐23 cells, but not the two differentiating cells lines, showed a large increase in cell organelles with time in culture. In particular, an increase in very small mitochondria was observed; these mitochon

ISSN:0021-9541    

DOI:10.1002/jcp.1041380109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractChanges in the packing of phospholipids in the plasma membrane of lymphocytes occur during differentiation within primary and secondary lymphoid organs. As they differentiate, lymphocytes interact with a variety of reticuloendothelial cells, including macrophages. To investigate a possible relation between these two phenomena, the strength of the interactions between lymphocytes and macrophages was measured in vitro as a function of the tightness of packing of phospholipids on the lymphocyte surface. Strength of adherence was measured by the ability of lymphocytes to remain adherent to macrophages when subjected to increasing centrifugal forces. Phospholipid packing was assessed using the fluorescent lipophilic probe merocyanine 540 (MC540), which preferentially binds to bilayers in which the lipids are more loosely packed. Three subpopulations of murine thymocytes were resolved with respect to strength of adherence to peritoneal or thymic macrophages. To determine whether these subpopulations corresponded with the three classes of cells distinguishable by MC540 fluorescence, populations enriched for staining or non‐staining cells, and cells sorted on the basis of MC540 fluorescence intensity, were examined. The least fluorescent cells were the least strongly adherent; the most fluorescent cells were the most strongly adherent; and cells of intermediate fluorescence had intermediate adherence. When splenic lymphocytes were examined with respect to adherence to peritoneal or splenic macrophages, similar patterns of fluorescence and adherence were seen. These results suggest that the organization of the plasma membrane lipid bilayer of lymphocytes may be involved in their interactions with macrophages during primary and secondary differentiation. The adherence signal for lymphocytes thus may be similar to that proposed for other blood cell

ISSN:0021-9541    

DOI:10.1002/jcp.1041380110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractEpidermal growth factor and cartilage‐derived basic fibroblast growth factor (EGF and CD‐bFGF) are mitogens shown to increase the rate of wound repair in animal models. In addition to being a mitogen for granulation tissue, CD‐bFGF stimulates the recruitment of cells to the wound site. CD‐bFGF and a closely‐related chondrosarcoma‐derived fibroblast growth factor stimulated chemotaxis of granulation tissue cells in vitro, each factor having a maximum activity at a concentration of 55 pM. Epidermal growth factor was also a potent chemoattractant for rat granulation tissue fibroblasts; however, maximum activity was obtained at 1.7 nM. Cells from all stages of wound repair were chemotactically responsive to these factors, but there was some attenuation of the response to bFGF in cells derived from fully‐organized day 28 granulation tissue. Collagenase‐catalyzed restructuring of collagen, an additional significant feature of wound repair, is probably critical to cell movement in an extracellular matrix. Cells derived from organizing (6–day old) sponge granulation tissue secreted latent collagenase constituitively in vitro. In the presence of serum, the production of collagenase was stimulated three‐four fold by 1.8 nM bFGF derived either from cartilage or chondrosarcoma. When serum was present, as at a wound site, collagenase production was not enhanced by the addition of EGF. Cells from fully organized, day 21 sponge granulation tissue did not secrete latent collagenase constitutively and could not be stimulated to do so by the addition of EGF, bFGF, or phorbol ester. Human skin fibroblast collagenase production was also stimulated by bFGF and was refractory to EGF. While both classes of growth factor have the ability to promote wound healing, the varying responses they elicit in cell populations from the wound site emphasize the different pathways of

ISSN:0021-9541    

DOI:10.1002/jcp.1041380111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY