Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Phenotypic modulation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources
PubMed2001

Modulation of dendritic cell phenotype and mobility by tumor cells in vitro.

To gain new insights into the functional interaction between DC and neoplastic cells, we have analyzed the effects of melanoma and colorectal cancer lines on the chemotaxis and the phenotype of monocyte-derived DC in vitro. Both types of tumor cells displayed effective chemoattractive capacity towards immature, but not mature DC. Furthermore, conditioned medium of discrete melanoma lines induced upregulation of CD80, CD86, MHC class I, and MHC class II molecules on immature DC. However, de novo expression of E-cadherin and strong upregulation of CD15 could also be detected in the absence of CD83 expression. Melanoma-conditioned DC exhibited an increased adhesion capacity to a melanoma cell line in vitro and did not migrate in response to SLC chemokine. Tumor-infiltrating CD15(+) cells displaying DC morphology could also be detected by immunohistochemistry in the original tumor specimens from which discrete melanoma cell lines under investigation were derived. Colorectal cancer cell lines, although able to chemoattract immature DC, were apparently unable to modulate their phenotype. Altogether our results suggest that tumor cells can attract immature DC in vitro and, eventually, modulate their phenotype. As a result, DC mobility could be severely impaired.

Animals↗
PubMed1991

Hepatocytes modulate the hepatic microvascular phenotype.

The liver microvasculature is unique among epithelial organs because it is composed of sinusoids rather than capillaries. Since hepatocytes lack a basement membrane, they are not separated from plasma by any continuous filtration barrier. During the cirrhotic process, the sinusoids become transformed into typical continuous capillaries with specialized endothelial junctions, continuous basement membrane, and pericytes. To explore the factors that determine the phenotype of the hepatic microvasculature, we implanted fetal rat liver fragments onto the chorioallantoid membrane of 6-day-old, shell-less, quail embryos. After 5 days in culture they were studied by light and electron microscopy immunohistochemistry using markers specific for: quail cells, hepatocytes, and basement membrane components of murine or avian origin. The normal quail chorioallantoid membrane is vascularized by continuous capillaries. The periphery of the transplanted fetal rat liver fragments becomes vascularized by microvessels of quail origin. However, the quail microvessels in the proximity of rat hepatocytes assume a sinusoidal phenotype with fenestrations lacking diaphragms, endothelial cell gaps, and devoid of basement membrane. These results demonstrate that liver cells modulate the phenotype of the hepatic microvascular. Since hepatocytes and endothelium do not establish direct cell contacts, we postulate that this modulation is exerted either by secreted soluble cytokines or by the extracellular matrix.

Animals↗
PubMed1998

Keratinocyte growth factor modulates alveolar epithelial cell phenotype in vitro: expression of aquaporin 5.

We investigated the role of keratinocyte growth factor (KGF) in regulation of alveolar epithelial cell (AEC) phenotype in vitro. Effects of KGF on cell morphology, expression of surfactant apoproteins A, B, and C (SP-A, -B, and -C), and expression of aquaporin 5 (AQP5), a water channel present in situ on the apical surface of alveolar type I (AT1) cells but not expressed in alveolar type II (AT2) cells, were evaluated in AECs grown in primary culture. Observations were made on AEC monolayers grown in serum-free medium without KGF (control) or grown continuously in the presence of KGF (10 ng/ml) from either Day 0 (i.e., the time of plating) or Day 4 or 6 through Day 8 in culture. AECs monolayers express AQP5 only on their apical surfaces as determined by cell surface biotinylation studies. Control AECs grown in the absence of KGF through Day 8 express increasing levels of AQP5, consistent with transition toward the AT1 cell phenotype. Exposure of AECs to KGF from Day 0 results in decreased AQP5 expression, retention of a cuboidal morphology, and greater numbers of lamellar bodies relative to control on Day 8 in culture. AECs treated with KGF from Day 4 or 6 exhibit a decrease in AQP5 expression through subsequent days in culture, as well as an increase in expression of surfactant apoproteins. These data, showing that KGF both prevents and reverses the increase in AQP5 (and decrease in surfactant apoprotein) expression that accompanies progression of the AT2 toward the AT1 cell phenotype, support the concepts that transdifferentiation between AT2 and AT1 cell phenotypes is at least partially reversible and that KGF may play a major role in modulating AEC phenotype.

Animals↗
PubMedDate not supplied

Modulation of the anchorage-independent phenotype of human lung fibroblasts obtained from fibrotic tissue following culture with retinoid and corticosteroid.

Fibroblast heterogeneity has been documented in fibrotic tissue from lung and skin. Differences have been demonstrated in proliferative rates in fibroblasts derived from fibrotic lung tissue as compared to normal. Fibroblast lines derived from adult fibrotic lung tissue and neonatal normal lung tissue exhibit colony growth in soft agarose culture, whereas fibroblast cell lines from normal adult lung tissue do not. The characteristic of anchorage-independent growth is consistent with the aggressive nature of the disease and with developmental lung growth. In this study, fibrotic lung fibroblasts were exposed to growth and differentiating factors to determine whether the anchorage-independent phenotype can be modulated. The results indicate that treatment of fibrotic lung fibroblasts with retinoic acid, known to modify matrix gene expression and induce differentiation, inhibits the cells ability to form colonies under soft agarose growth. Treatment with all-trans-retinoic acid yielded the greatest effect inhibiting both IPF and neonatal lung fibroblast anchorage-independent growth approximately 90% at 10(-6) M. Treatment of IPF fibroblasts with all-trans-retinoic acid also inhibited corticosteroid-induced colony growth. Modulation of the "fibrotic" fibroblast phenotype through retinoid therapy may prove beneficial as a potential therapeutic strategy.

Adrenal Cortex Hormones↗
PubMed2005

Using affect-modulated startle to study phenotypes of pediatric bipolar disorder.

OBJECTIVES: Affective neuroscience research that investigates core symptoms of pediatric bipolar disorder (PBD) may be effective in differentiating PBD phenotypes. The current study used affect-modulated startle to examine potential differences in reactivity to emotional stimuli (reward and punishment) in narrow and broad phenotype PBD and controls. METHODS: Thirty children meeting DSM-IV bipolar disorder criteria (i.e. narrow phenotype PBD with defined manic episodes with elevated/expansive mood), 19 children meeting criteria for severe mood dysregulation (i.e. broad phenotype with chronic irritability, hyper-reactivity, and hyperarousal), and 19 controls completed a lottery startle paradigm involving reward (money) and punishment (loud noise). Startle probes were presented during anticipation of the emotional stimulus, immediately following the presentation of the stimulus, or during return to baseline following the stimulus. RESULTS: By self-report, patients and controls found the putative punishment to be preferable to the neutral condition. In the reward condition, patient samples reported greater arousal than did controls, but no between-group differences were found on the magnitude of startle response during the reward, punishment, or neutral conditions. CONCLUSIONS: The failure to find differences in affect-modulated startle between control children and those with narrow or broad PBD phenotypes speaks to the methodological challenges associated with studying reward mechanisms in PBD. Alternative paradigms that focus on different aspects of reward mechanisms are discussed.

Acoustic Stimulation↗
PubMed1997

Differential modulation of the cholinergic phenotype of the nucleus basalis magnocellularis neurons by applying NGF at the cell body or cortical terminal fields.

Although it is well known that exogenous nerve growth factor (NGF) can dramatically affect the phenotype of the basal forebrain cholinergic neurons in normal, aged, or lesioned animals, whether its actions are restricted to the terminal field level of these cholinergic neurons has yet to be established. In most cases, NGF has been applied into the cerebroventricle space giving it access to both the terminal fields and somatodendritic regions. The recent demonstration that TrkA, the essential component of high-affinity NGF receptors, is expressed not only at the distal fields (terminals and distal axons) but also at the proximal fields (cell bodies, dendrites, and proximal axons) of the basal forebrain cholinergic neurons has provoked renewed interest in this problem. More recently, it was further demonstrated that in Alzheimer's disease (AD), the NGF peptide increased throughout the brain but decreased in the nucleus basalis magnocellularis (NBM), suggesting that there is an impaired retrograde transport of NGF from the cortex to the NBM. Thus, it will be crucial to clarify whether or not the TrkA receptors on the somatodendritic fields of the NBM cholinergic neurons respond to exogenous NGF in order to support the rationale for site-directed neurotrophic factor therapy in AD or other neurological disorders. To clarify this issue, we delivered 2.5S purified mouse NGF locally into the cortex or corpus striatum adjacent to the NBM of naive and cortically devascularized mature male Wistar rats. The local distribution of exogenous NGF was demonstrated by immunohistochemical staining. In naive rats, an NGF dose of 84.00 or 16.80 microg infused into either the cortex or the corpus striatum for 2 weeks caused ipsilateral hypertrophy of the cholinergic neurons of the NBM. In cortically devascularized animals, an NGF dose of 84.00 microg delivered into the cortex and 84.00 microg or 16.80 microg infused into the striatum adjacent to the NBM for 2 weeks rescued the ipsilateral cholinergic phenotype of NBM neurons of the basolocortical pathway from retrograde degeneration. Thus, exogenous NGF can affect the cholinergic phenotype of the NBM regardless of whether it is presented to their nerve terminal fields or their somatodendritic region. The present results provide new evidence that the TrkA receptors present in the somatodendritic region of the cholinergic neurons of the NBM are functional and capable of modulating neuronal phenotype in the naive and lesioned CNS, when applied pharmacologically.

Animals↗
PubMed1995

Differential dependence of TH-0, TH-1 and TH-2 CD4+ T cells on co-stimulatory activity provided by the accessory molecule LFA-1.

BACKGROUND: The adhesion molecule LFA-1 contributes to the activation response of peripheral blood human CD4+ T cells. Less is known of its contribution to stimulation of long-term CD4+ T cell lines and clones or of its potential to co-stimulate CD4+ T cells of different functional phenotype. OBJECTIVE: This study was therefore performed to investigate co-stimulatory properties of the LFA-1 (CD11a/CD18) complex in the activation of human CD4+ T cell lines and clones of TH-0, TH-1 and TH-2 subsets. METHODS: Co-stimulatory activity was measured by cross-linking antibodies to CD11a or CD18 with anti-CD3 antibodies to plastic and then measuring the proliferative response of CD4+ T cells to these antibodies. RESULTS: A house duct mite allergen-specific CD4+ T cell line (TH-2) demonstrated much greater dependence on both CD11a and CD18 than a mycobacterial antigen-specific CD4+ T cell line (TH-1). Co-stimulatory activity through LFA-1 was also provided to a house dust mite-specific CD4+ T cell clone (DE-9; TH-2) but not to an influenza haemagglutinin-specific CD4+ T cell clone (HA1-7; TH-0). In contrast, soluble antibodies to CD18 inhibited proliferative responses of both DE-9 and HA1.7 to an immunogenic challenge of antigen and to stimulation by anti-CD3 antibodies. However, the allergen-specific T cells were more susceptible to inhibition. Signal transduction was also observed from the T-cell receptor to LFA-1. Ligation of the T-cell receptor modulated the phenotypic expression of LFA-1 and ICAM-1 on both HA1.7 and DE-9. Phenotypic modulation was observed as a result of both activation and the induction of non-responsiveness. CONCLUSION: These experiments indicate that CD4+ T cells of TH-2 functional phenotype may have a greater requirement for the co-stimulatory activity of LFA-1 than CD4+ T cells of TH-0 or TH-1 phenotypes.

Antibodies, Monoclonal↗
PubMed1971

Immunoglobulin and other surface antigens of cells of the immune system.

Immunoglobulins (Ig) on cells of the immune system: The cytotoxicity test, with class-specific and type-specific anti-Ig sera, identifies kappa and micro determinants on mouse lymphocytes. The proportion of kappa(+) cells is characteristic for each source of cells: 30% of bone marrow cells, 40% of cells from peripheral lymph nodes, 45% of lymphocytes from peripheral blood or peritoneal cavity, and 50% of spleen cells. No Ig was demonstrable on thymocytes or on leukemia cells (most of which arise from thymus-derived [T] cells). Cytotoxicity tests were performed on various myelomas secreting different Ig; the only positive reactions were given by kappagamma1 myelomas (all four kappagamma1 myelomas tested were sensitive to both anti-kappa and anti-gamma1). Hemolytic plaque-forming cells (PFC) of IgG type had no demonstrable surface Ig, but a proportion of IgM PFC were kappa(+)micro(+). Virtually all rosette-forming cells (RFC) have surface Ig, more than 90% of them being inhibited by anti-kappa, 50% by anti-micro, and 10-30% by antisera to other heavy chains. Anti-lambda sera gave no positive reactions with any cell type, which is in keeping with the low level of this light chain in mouse serum. Ig and other differentiation antigens as markers for T and B cells: Thymocytes are hallmarked by the alloantigens TL, theta, and the Ly series, and it is generally held that extrathymic lymphoid cells that bear them are derived from thymocytes. There is one alloantigen marker for the thymus-independent (B) cell, and that is PC, which appears late in differentiation. (The mouse-specific lymphocyte (MSLA) and mouse-specific bone marrow-derived lymphocyte (MBLA) antigens recognized by heteroantisera, not used in the present study, are other candidates for T and B cell markers.) Making use of antisera to these surface antigens to inhibit the function of cells that carry them, we find the following: Approximately 30% of RFC, 60% of IgM PFC, and 90% of IgG are PC(+) and so are identified as B cells. No T markers were demonstrable on these cell populations. Thus if T cells do become RFC or PFC they presumably lose their T surface markers in the process (cf. the quantitative reduction of T markers accompanying the thymocyte --> lymphocyte transition). Cells that have the potential to initiate graft-versus-host (GVH) reactions have the T cell surface phenotype theta(+)Ig(-). Adoptive transfer of thymus-dependent antibody-forming capacity (response to sheep erythrocytes) required theta(+) cells but transfer of a thymus-independent immune response to Brucella antigen did not. Cells with surface Ig were involved in both types of adoptive transfers. Thus the presently available T markers do not provide evidence for T cells carrying surface Ig. Suppression of the Ig phenotype by antibody: antigenic modulation? A phenotypic change from Ig(+) to Ig(-) occurs when Ig(+) lymphocytes or myeloma cells are incubated with anti-Ig sera in vitro in the absence of complement (C). As with antigenic modulation in the TL system, which it resembles, this phenomenon is temperature dependent and in the case of lymph node cells (LNC) can be inhibited by high doses of actinomycin D.

Animals↗
PubMed1993

Effects of signalling transduction modulators on the transformed phenotypes in v-H-ras-transformed NIH 3T3 cells.

Several signalling transduction modulators were used to examine their effects on the morphological changes, foci formation in soft agar and cellular growth in v-H-ras-transformed NIH 3T3 cells. The results from this study showed that specific tyrosine kinase inhibitors (genistein and tyrphostin 23) and cyclic AMP-elevating agents (forskolin and 3-isobutyl-1-methyl-xanthine) could effectively induce differential flat phenotype of v-H-ras transformant at micromolar concentrations. At the same dose range, both signalling modulators also caused a significant suppression of anchorage-independent and cellular growth in the same transformant. By contrast, compound inhibitors such as protein kinase C (staurosporin and H-7), phospholipase A2 (aristolochic acid), phospholipase C (neomycin sulfate) and cyclooxygenase (indomethacin) all did not alter the cellular morphology or foci formation in soft agar, although PKC inhibitors exhibited a slight inhibition on the cellular growth. Based on these observations, we propose that the alterations of protein kinase A or tyrosine kinase-associated signal pathways is necessary and the original cause of the transformation event, but that increase of the activities of protein kinase C, phospholipase C, phospholipase A2 or cyclooxygenase probably is an indirect result of the v-H-ras-mediated transformation.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Apolipoprotein E2 transgenic rabbits. Modulation of the type III hyperlipoproteinemic phenotype by estrogen and occurrence of spontaneous atherosclerosis.

Transgenic rabbits were produced that expressed high plasma levels (30-70 mg/dl) of human apolipoprotein (apo) E2(Cys-158), an apoE variant associated with the human genetic disorder type III hyperlipoproteinemia (HLP). Male transgenic rabbits fed normal chow had up to 8-fold (289 +/- 148 mg/dl) and 15-fold (697 +/- 452 mg/dl) increases in plasma total cholesterol and triglycerides, respectively, compared with nontransgenic males. Female transgenic rabbits had only a modest hyperlipidemia (total cholesterol, 140 +/- 46 mg/dl; total triglycerides, 174 +/- 66 mg/dl). Both sexes displayed the hallmarks fo type III HLP: beta-migrating very low density lipoproteins (beta-VLDL) (intestinal and hepatic remnant lipoproteins) and significantly increased VLDL and intermediate density lipoproteins. Apolipoprotein E2-containing VLDL particles were cleared from teh circulation more slowly and were more resistant to lipoprotein lipase-mediated lipolysis than normal VLDL. Only females had increased high density lipoproteins (HDL) (40%), which were shifted from typical small HDL to larger HDL1. Plasma apoE2 was predominantly associated with beta-VLDL in males and with HDL in females. To ascertain reasons for the phenotypic gender difference, we treated male transgenic rabbits with 17alpha-ethinyl estradiol. Estrogen treatment for 10 days dramatically decreased total cholesterol (73%) and triglycerides (89%) and converted beta-VLDL to pre-beta-migrating VLDL. Concomitantly, lipoprotein lipase and hepatic lipase activities increased by 90%, low density lipoprotein receptor activity was stimulated significantly, apoE2 was redistributed to HDL, and HDL were converted to HDL1. Conversely, ovariectomy in female transgenic rabbits significantly increased total cholesterol (75%), triglycerides (117%), and beta-VLDL, while decreasing lipoprotein lipase and hepatic lipase activities by 35% and redistributing apoE2 to the beta-VLDL. Thus, estrogen status appears to be responsible for much of the gender difference of the lipoprotein phenotype, mainly by modulating both lipase and low density lipoprotein receptor activities. Furthermore, transgenic rabbits fed normal chow for 11 months developed fatty streaks, and some had more advanced atherosclerotic lesions, especially around the aortic arch and proximal abdominal aorta. The lesions were more extensive in males, roughly correlating with the magnitude of the hyperlipidemia. Therefore, high plasma levels of human apoE2 in transgenic rabbits result in a type III HLP phenotype, in which males have both more severe hyperlipidemia and more extensive atherosclerosis than females.

Animals↗
PubMed1996

A modular misexpression screen in Drosophila detecting tissue-specific phenotypes.

Genetic screens in Drosophila have lead to the discovery of many genes important for patterning and signal transduction in diverse organisms. Traditionally, the phenotypic effects of loss-of-function mutations are analyzed. As an alternative way to link genes and function, I have developed a versatile misexpression screen in Drosophila, the first such screen in higher eukaryotes. The screen identifies genes that, when over- or misexpressed in a pattern of interest, give a specific phenotype or modulate an existing mutant phenotype. It is based on Gal4 transactivation of a mobile enhancer and promoter that "targets" random endogenous genes for expression. The modular design of the screen allows directed expression in any temporal or spatial pattern. When activated in the developing eye, 4% of target inserts gave dominant phenotypes. One insertion was in the gene encoding Ras GTPase-activating protein; its overexpression phenotype was strongly enhanced by a mutation in Ras1. Thus, biologically relevant phenotypes and genetic interactions are identified using this method. The screen is a powerful new tool for developmental genetics; similar approaches can also be developed for other organisms.

Animals↗
PubMed1992

Modulation of the antigenic phenotype of human breast carcinoma cells by modifiers of protein kinase C activity and recombinant human interferons.

In the present study we have analyzed the effect of a synthetic protein kinase C (PKC) activator 3-(N-acetylamino)-5-(N-decyl-N-methylamino)-benzyl alcohol (ADMB) and the natural PKC-activating tumor-promoting agents 12-O-tetradecanoylphorbol 13-acetate (TPA) and mezerein on the antigenic phenotype of T47D human breast carcinoma cells. All three agents increased the surface expression of the tumor-associated antigen BCA 225 and various cellular antigens, including HLA class II antigens, intercellular adhesion molecule 1 (ICAM-1) and c-erbB-2. Expression of the same antigens was also upregulated to various extents in T47D cells by recombinant fibroblast (IFN beta) and immune (IFN gamma) interferon. Shedding of BCA 225 from T47D cells was induced by TPA, mezerein, IFN beta and IFN gamma, whereas ADMB did not display this activity. The ability of ADMB, TPA and mezerein to modulate the antigenic phenotype of T47D cells appears to involve a PKC-mediated pathway, since the PKC inhibitor, H-7, eliminates antigenic modulation. In contrast, the ability of IFN beta and IFN gamma to enhance the synthesis, expression and shedding of BCA 225, as well as to enhance HLA class II antigens, c-erbB-2 and ICAM-1 expression, was either unchanged or modestly reduced by simultaneous exposure to H-7. Analysis of steady-state mRNA levels for HLA class I antigens, HLA class II-DR beta antigen, ICAM-1 and c-erbB-2 indicated that the ability of H-7 to inhibit expression of these antigens in TPA-, mezerein- and ADMB-treated cells was not a consequence of a reduction in the steady-state levels of mRNAs for these antigens. The results of the present investigation indicate that the biochemical pathways mediating enhanced antigenic expression in T47D cells induced by TPA, mezerein and the synthetic PKC activator ADMB are different from those induced by recombinant interferons. Furthermore, up-regulation of antigenic expression in T47D cells can occur by a PKC-dependent or a PKC-independent pathway.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Interleukin-1 beta modulates the growth and phenotype of neonatal rat cardiac myocytes.

Mononuclear cell infiltration and local cytokine elaboration are hallmarks of inflammatory and immunologic heart diseases. To test the hypothesis that cytokines can modulate cardiac myocyte growth and phenotype, myocytes cultured from neonatal rat hearts were exposed to IL-1 beta, an inflammatory cytokine prevalent in myocardial inflammation. IL-1 beta (2 ng/ml, 24 h) increased [3H]leucine incorporation by 30 +/- 4% (P < 0.001, n = 29) and net cellular protein content by 20 +/- 4% (P < 0.001, n = 27), but had no effect on DNA synthesis. Northern hybridization showed that IL-1 beta increased prepro-atrial natriuretic factor (ANF) mRNA (5.8 +/- 1.5-fold, P < 0.01, n = 13) and beta-myosin heavy chain (beta-MHC) mRNA (> 10-fold, n = 4), and decreased mRNA levels for sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) (-46 +/- 7%; P < 0.001; n = 11), calcium release channel (CRC) (-65 +/- 11%, P < 0.001, n = 8) and voltage-dependent calcium channel (VDCC) (-53 +/- 7%, P < 0.001, n = 8). NG-monomethyl-L-arginine (1 mM), an inhibitor of nitric oxide (NO) synthesis, did not inhibit the IL-1 beta-induced protein synthesis or changes in mRNA levels. In ventricular myocardium obtained from adult rats treated with lipopolysaccharide (4 mg/kg intraperitoneally 18 h) to stimulate systemic cytokine production, there were changes in the mRNA levels for beta-MHC (6 +/- 1-fold, P < 0.01, n = 4), SERCA2 (-65 +/- 4%, P < 0.0001, n = 4), CRC (-67 +/- 5%, P < 0.001, n = 4), and VDCC (-58 +/- 5%, P < 0.001; n = 4) that were qualitatively similar to those observed in cultured myocytes. Thus, IL-1 beta, acting via an NO-independent mechanism, caused myocyte hypertrophy associated with induction of fetal genes (ANF and beta-MHC) and downregulation of three important calcium regulatory genes (SERCA2, CRC, and VDCC). IL-1 beta may contribute to the abnormal structural and functional alterations of cardiac myocytes in conditions marked by mononuclear cell infiltration.

Animals↗
PubMed2005

Agouti-related protein-deficient mice display an age-related lean phenotype.

Endogenous modulators of the central melanocortin system, such as the agouti-related protein (AgRP), should hold a pivotal position in the regulation of energy intake and expenditure. Despite this, AgRP-deficient mice were recently reported to exhibit normal food intake, body weight gain, and energy expenditure. Here we demonstrate that 2- to 3-month-old Agrp null mice do in fact exhibit subtle changes in response to feeding challenges (fasting and MCR agonists) but, of more significance and magnitude, exhibit reduced body weight and adiposity after 6 months of age. This age-dependent lean phenotype is correlated with increased metabolic rate, body temperature, and locomotor activity and increased circulating thyroid hormone (T4 and T3) and BAT UCP-1 expression. These results provide further proof of the importance of the AgRP neuronal system in the regulation of energy homeostasis.

Adipose Tissue↗
PubMed1981

Progressive loss of shape-responsive metabolic controls in cells with increasingly transformed phenotype.

The modulation of cell metabolism by cell shape and external surface contact has been studied by suspension culture of anchorage-dependent fibroblasts. The suspended cells shut down protein synthesis and nuclear RNA metabolism and cease replicating DNA. However, these responses to suspension are lost or modified as cells become progressively transformed in behavior. We compare the metabolic consequences of suspension culture in five related types of fibroblasts: the well regulated mouse diploid fibroblast; the spontaneously immortalized and progressively less well regulated lines 3T3, 3T6 and HDP3T6; and the fully transformed anchorage-independent SVPy3T3. Protein synthesis is inhibited rapidly following suspension in diploid fibroblasts and more slowly in the less well regulated cells. In contrast, the response of hnRNA synthesis to suspension is lost completely when cells adopt the 3T6 phenotype, and message regulation is lost in HDP3T6. The prompt inhibition of ribosomal RNA precursor is modified to a slow decline in HDP3T6. The metabolism of fully transformed SVPy3T3 cells is indifferent to suspension. The progressive loss of shape-responsive controls may be related to tumor progression.

Animals↗
PubMed1994

Modulation of the differentiated phenotype of keratinocytes of the hair follicle and from epidermis.

The differentiation capacity and its modulation by cell-cell and cell-matrix interactions of epithelial cells from epidermis (NEK), hair follicle outer root sheath (ORS) and hair matrix cells (HMC) in different experimental model systems is reviewed. Reformation of structurally intact and functioning hair follicles has been achieved with isolated neonatal mouse cells in vivo when follicular epithelia and dermal fibroblasts were transplanted. This structural reorganization has not yet been feasible in vitro in either surface or matrix embedded organotypic cocultures with mesenchymal cells. While the epithelial cells isolated from epidermis or hair follicle compartments formed similar stratified and keratinizing epithelia in vitro, their degree of differentiation was significantly different, declining from NEK over ORS to HMC. Differentiation was further reduced in HMC cultures in the presence of dermal papilla cells (DPC). Differentiation was analyzed by morphologic criteria and the biochemical analysis as well as immunohistochemical localization of differentiation products such as keratins, involucrin, filaggrin, integrins, basement membrane components and membrane antigens. The results demonstrate fully maintained differentiation capacity of skin and appendage-keratinocytes to reconstitute a squamous epithelium, reflecting their common origin from embryonic epidermis. For the induction of hair follicle-specific structural and functional characteristics, different and probably more complex interactive mechanisms may be required.

Animals↗
PubMed1995

Loss of transcriptional attenuation in N-myc is associated with progression towards a more malignant phenotype.

The modulation of RNA polymerase II processivity through the untranslated N-myc first exon represents an important mechanism governing N-myc mRNA levels during normal development. In this study, we employed the rat embryo fibroblast (REF) cooperation assay as a functional means to (i) map N-myc first exon sequences involved in the regulation of N-myc gene expression and specifically their contribution to controlling a block to transcriptional elongation and (ii) determine whether this transcriptional control mechanism plays a role in governing the oncogenic activity of N-myc. Transfection of N-myc expression constructs harboring various deletions within the untranslated first exon revealed that a region encoding a potential stem-loop structure followed by a thymine stretch (stem-loop/T region) was required for efficient transcriptional attenuation. The increase in transcriptional read-through associated with all deletions involving the stem-loop/T region also resulted in a more aggressive malignant phenotype as evidenced by a significant enhancement in the subcloning efficiency of N-myc/ras transformed foci. Most significantly, when cell lines generated from overexpression of the intact N-myc expression construct were selected for anchorage-independent growth, a strong block to transcriptional elongation was completely eliminated in all cases examined. Since the subcloning efficiency of transformed foci and the capacity of permanently established cell lines for anchorage-independent growth are direct correlates of more advanced stages of malignant transformation, our findings suggest that loss of transcriptional attenuation represents an important genetic event in the progression of N-myc-induced cellular transformation.

Animals↗
PubMed1996

Fc gamma receptor expression on sheep afferent lymph dendritic cells and rapid modulation of cell surface phenotype following Fc gamma receptor engagement in vitro and in vivo.

Afferent lymph dendritic cells were analysed for the presence of Fc gamma receptors by Western blotting and for modulation of surface markers following Fc gamma receptor engagement in vitro and in vivo. The results showed that unstimulated dendritic cells expressed Fc gamma RII constitutively. When dendritic cells were incubated in vitro with antigen/antibody complexes in antibody excess, a marked reduction in surface staining was observed for MHC class II, CD1, CD44, and VLA-4 after 8 h in culture. These changes did not occur with antigen or antibody alone. DC expression of LFA-1 and LFA-3 were slightly reduced after 8 h in culture with Ova alone, but this was enhanced slightly when the cells were cultured with immune complexes. Even more marked reductions in surface staining for MHC class II, CD1, CD44 and VLA-4 were observed on dendritic cells 4-8 h following secondary antigen challenge in vivo. LFA-1 and LFA-3 expression was reduced only slightly. The level of expression of MHC class II, CD1, LFA-1 and LFA-3 was substantially increased over resting values 24 h after Fc gamma R occupancy. The intensity of staining at this time was also significantly elevated for CD44, LFA-1, LFA-3 and VLA-4. These results show that engagement of Fc gamma receptors cause a substantial modulation of the dendritic cell surface phenotype after immune complex uptake. The phenomenon may function to maximize subsequent presentation of the challenge antigen to T cells.

Animals↗