Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “differentiation”

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 361 records · Page 20Linked to original sources

Identification of a precursor to phosphatidyl choline-specific B-1 cells suggesting that B-1 cells differentiate from splenic conventional B cells in vivo: cyclosporin A blocks differentiation to B-1.

The origin of B-1 cells is controversial. The initial paradigm posited that B-1 and B-2 cells derive from separate lineages. More recently it has been argued that B-1 cells derive from conventional B cells as a result of T-independent Ag activation. To understand B-1 cell differentiation, we have generated Ig transgenic (Tg) mice using the H and L chain genes (VH12 and Vkappa4) of anti-phosphatidyl choline (anti-PtC) B cells. In normal mice anti-PtC B cells segregate to B-1. Segregation is intact in VH12 (6-1) and VH12/Vkappa4 (double) Tg mice that develop large numbers of PtC-specific B cells. However, if B-1 cell differentiation is blocked, anti-PtC B cells in these Tg mice are B-2-like in phenotype, suggesting the existence of an Ag-driven differentiative pathway from B-2 to B-1. In this study, we show that double Tg mice have a population of anti-PtC B cells that have the phenotypic characteristics of both B-2 and B-1 cells and that have the potential to differentiate to B-1 (B-1a and B-1b). Cyclosporin A blocks this differentiation and induces a more B-2-like phenotype in these cells. These findings indicate that these cells are intermediate between B-2 and B-1, further evidence of a B-2 to B-1 differentiative pathway.

Animals↗

p53 and p21waf-1 expression correlates with apoptosis or cell survival in poorly differentiated, but not well-differentiated, retinoblastomas.

In human retinoblastomas, rare genetic mutations of the retinoblastoma gene cause massive cell proliferation, altered differentiation, and tumor formation; but paradoxically, this is accompanied by extensive apoptotic cell loss. We quantified the immunohistochemical distribution of p53, its downstream effector p21 (WAF-1), and apoptotic cells in 50 human retinoblastomas, within three concentric zones of sleeves of tumor cells surrounding blood vessels. In poorly differentiated retinoblastomas, both p53 expression and apoptosis increase toward the outer zone of tumor sleeves, whereas p21 expression occurs primarily within the inner zone. This staining pattern of p53 expression is reversed in well-differentiated tumors, whereas p21 staining and apoptotic cell distributions are unchanged. We detected no p53 mutations in four retinoblastomas and two retinoblastoma cell lines. We postulate that oxygen and cell "survival/growth factors" delivered via blood vessels protect retinoblastoma cells from apoptosis. In poorly differentiated tumors, apoptosis is spatially associated with increased p53 expression and may be p53 mediated, but in well-differentiated tumors, apoptosis does not colocalize with p53 and may be p53 independent. In retinoblastomas, p21 is involved not in cell death by apoptosis but in cell survival. Thus, p53 varies its expression (and by implication its function) with altered differentiation in retinoblastomas.

Apoptosis↗

The PPARgamma ligands PGJ2 and rosiglitazone show a differential ability to inhibit proliferation and to induce apoptosis and differentiation of human glioblastoma cell lines.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is involved in the control of cell proliferation, apoptosis and differentiation in various tumor cells. Among PPARgamma ligands, 15-deoxy-Delta12,14-prostaglandin J2 (PGJ2), the ultimate metabolite of PGD2, plays a role in the biology of brain tumors. It is still unclear to which extent the anti-proliferative and differentiation-promoting activity of PGJ2 is mediated through PPARgamma. We compared the effects of PGJ2 with those of rosiglitazone - the synthetic agonist with the highest affinity for PPARgamma - in 4 human glioblastoma cell lines (A172, U87-MG, M059K, M059J). All cell lines expressed high levels of PPARgamma, consistent with the high levels of PPARgamma protein in 5 tumor samples. Both PGJ2 and rosiglitazone inhibited proliferation of all cell lines with a G2/M arrest and apoptosis, but only PGJ2 up-regulated p21Cip/WAF1. The growth inhibitory effect was partially reversed by the PPARgamma antagonist GW9662. We studied the time sequence of selected molecular events, that lead glioblastoma cells to apoptosis and/or differentiation, after treatment with both agonists. M059K cells committed to undergo apoptosis by PGJ2, initially up-regulated PPARgamma, and then down-regulated PPARgamma as they began apoptosis. Apoptotic cells also increased their expression of retinoic acid receptor beta (RARbeta) and retinoid X receptor alpha (RXRalpha). PGJ2 increased expression of glial fibrillary acidic protein (GFAP) and decreased levels of vimentin, structural proteins modulated during astrocytic differentiation. Unexpectedly, PGJ2 up-regulated the expression of cyclooxygenase-2 (COX-2). Rosiglitazone caused the same pattern of PPARgamma, RARbeta and RXRalpha expression as PGJ2, but no significant modulation of p21Cip/WAF1, cytoskeletal proteins or COX-2 occurred. Our data indicate that PGJ2, and rosiglitazone suppress cell proliferation and cause apoptosis in glioblastoma cell lines, most likely through a PPARgamma-dependent pathway. By contrast, the modulation of differentiation-associated proteins by PGJ2, but not rosiglitazone, suggests that PGJ2 promotes differentiation of glioblastoma cells independently of PPARgamma activation.

Apoptosis↗

The identification and characterization of a novel human differentiation-inhibiting protein that selectively blocks erythroid differentiation.

We have isolated a novel inhibitor of erythropoietic differentiation from the plasma of a patient suffering from idiopathic pure red cell aplasia. This differentiation-inhibiting protein (DIP) specifically blocked the differentiation of human burst-forming unit-erythroid (BFU-E), but not colony-forming unit-erythroid (CFU-E) cells. DIP also blocked the maturation of murine BFU-E cells, but not CFU-E or CFU-granulocyte-macrophage cells, and it inhibited the dimethyl sulfoxide (DMSO)-induced differentiation of Friend murine erythroleukemia cells (FLC) at levels between 10(-10) and 10(-12) mol/L. DIP activity was not detectable in the plasma of normal, healthy subjects. Unlike other known inhibitors of hematopoiesis, DIP appears to directly inhibit erythropoietic differentiation, because it did not affect the proliferation of untreated FLC and it effectively blocked FLC hemoglobinization without affecting the ability of the blocked cells to proliferate. DIP blocked FLC differentiation only when added to the culture medium within 1 hour of inducing the cells with DMSO, suggesting that the protein inhibited an early, but critical, DMSO-induced cellular process. DIP appears to be at least partially responsible for the patient's anemia, and its unique activity suggests a role in the early development of some erythroleukemias.

Animals↗

Microarray profiling of genes differentially expressed during erythroid differentiation of murine erythroleukemia cells.

Murine erythroleukemia (MEL) cells are widely used to study erythroid differentiation thanks to their ability to terminally differentiate in vitro in response to chemical induction. At the molecular level, not much is known of their terminal differentiation apart from activation of adult-type globin gene expression. We examined changes in gene expression during the terminal differentiation of these cells using microarray-based technology. We identified 180 genes whose expression changed significantly during differentiation. The microarray data were analyzed by hierarchical and k-means clustering and confirmed by semi-quantitative RT-PCR. We identified several genes including H1f0, Bnip3, Mgl2, ST7L, and Cbll1 that could be useful markers for erythropoiesis. These genetic markers should be a valuable resource both as potential regulators in functional studies of erythroid differentiation, and as straightforward cell type markers.

Acetamides↗

Effects of protein kinase A and calcium/phospholipid-dependent kinase modulators in the process of HL-60 cell differentiation: their opposite effects between HL-60 cell and K-562 cell differentiation.

We have previously shown that HL-60 cells treated with 1 alpha, 25-(OH)2D3 in magnesium-deficient medium are committed to differentiate but do not express differentiation-related phenotypes. In the present study, we demonstrated that Mg2+ deprivation blocked the process of differentiation before the induction of lysozyme mRNA and that the process of HL-60 cell differentiation could be divided into two steps, i.e., a commitment step and a phenotypic expression step. We studied the effects of protein kinase A (PKA) and calcium/phospholipid-dependent protein kinase (PKC) modulators at each step. The results indicated that agonists of PKA enhanced both steps but that N-(2-[methylamino]ethyl-5-isoquinolinesulfonamide inhibited them. On the other hand, 1-oleyl-2-acetylglycerol and 12-O-tetradecanoylphorbol-13-acetate enhanced the commitment step but inhibited that of phenotypic expression. Staurosporine and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine inhibited the commitment step and enhanced that of phenotypic expression. These results indicate that PKA acts as a positive regulatory signal and that PKC has a dual role in the process of HL-60 cell differentiation, i.e., as a positive regulatory signal in the commitment step and as a negative one in the phenotypic expression step. Recently, we have also shown that in K-562 cell differentiation into erythroid lineage, PKA may serve as a negative regulatory signal in both steps; however, PKC may act dually, namely as a negative regulatory signal in the commitment step and as a positive one in the phenotypic expression step.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗

Differential regulation of beta 1- and beta 2-adrenergic receptor protein and mRNA levels by glucocorticoids during 3T3-F442A adipose differentiation.

The regulation by dexamethasone of beta 1- and beta 2-adrenergic receptor expression during the adipose differentiation of 3T3-F442A cells was investigated at the receptor protein and mRNA level. Preadipocytes were poorly responsive to beta-adrenergic receptor (beta-AR) agonists and expressed few beta-ARs (approximately 3,000 sites/cell) solely of beta 1 subtype. Differentiation increased adrenergic sensitivity and total beta-AR number (approximately 16,000 sites/cell) with a beta 1/beta 2 ratio of approximately 90/10. Long term exposure of either differentiating cells or mature adipocytes to dexamethasone induced down-regulation of (-)-isoproterenol-sensitive adenylate cyclase activity which paralleled a 2- to 3.5-fold decrease in beta-ARs, while the beta 1/beta 2 ratio switched to approximately 20/80. The ratios of beta 1/beta 2 binding sites were always consistent with the rank order of potency of beta-adrenergic agonists in stimulating the adenylate cyclase system. The action of steroid agonists and antagonist suggested a glucocorticoid receptor-mediated mechanism. The beta 1-AR mRNA (3.2 kilobases) was stimulated 3-4.7 times in differentiated cells, as compared with preadipose cells; this beta 1-AR transcript was repressed in dexamethasone-treated cells. The beta 2-AR mRNA species (2.3 kilobases), absent in preadipocytes, was expressed at low levels in untreated adipocytes, but reached 11-fold this level in dexamethasone-exposed cells. The switch in receptor subtype protein and mRNA levels elicited by dexamethasone demonstrates the differential genetic control by glucocorticoids of beta-AR subtype expression in 3T3-F442A cells. We suggest that this regulation of beta-AR gene expression requires interactions of glucocorticoid receptors with specific DNA targets and with one (or several) transcription factor(s) that are cell- and differentiation state-dependent.

Adenylyl Cyclases↗

Cytokine-dependent granulocytic differentiation. Regulation of proliferative and differentiative responses in a murine progenitor cell line.

Human granulocyte colony stimulating factor (G-CSF) can support the survival and short term proliferation of the interleukin 3 (IL 3)-dependent diploid murine hemopoietic progenitor cell line 32D C13. After 8 days in the presence of 30 U/ml of G-CSF and in the absence of IL 3, the great majority of 32D C13 cells becomes positive for myeloperoxidase (a marker that appears at the promyelocytic stage of the granulocytic lineage) and progressively differentiates into lactoferrin-containing neutrophilic granulocytes. Myeloperoxidase mRNA rapidly increases after 24 to 48 hr of treatment with G-CSF, peaks at day 6 and is no longer detectable at day 9 and 12, paralleling the appearance of myeloperoxidase-positive promyelocytes and myelocytes in the culture. After 12 days, 100% of the cells terminally differentiate, and clonogenic assays in IL 3-containing semisolid media indicate that the whole population has irreversibly lost proliferative capability. By using varying concentrations of both murine IL 3 and recombinant human G-CSF, the cultures develop an heterogeneous population of cells representing all the differentiation stages of the myeloid lineage, and the relative ratios of immature proliferating precursors and terminally differentiated cells present in the cultures can be modulated by modifying the concentrations of IL 3 or recombinant human G-CSF. Isobolic curves indicate that IL 3 and G-CSF have an antagonistic effect on the proliferation of 32D C13 cells. Thus, these cells represent a simplified in vitro model of normal granulocytic differentiation whose extent may be modulated completely in the presence of serum by two well-defined growth and differentiation factors: IL 3 and G-CSF.

Animals↗

[Bioactive sialoglycosphingolipids (gangliosides): differentiation-inducers as well as differentiation-markers in human hematopoietic cells].

Glycosphingolipids (GSLs), which are amphipathic molecules composed of both hydrophobic and hydrophilic moieties and synthesized by a group of Golgi enzymes, glycosyltransferases, are located almost exclusively on the outer leaflet of plasma membranes of mammalian cells in general, and recently have become known to show an unexpectedly vast molecular heterogeneity. Furthermore, GSLs have been considered to be involved in cellular interactions and cell growth regulations, changing characteristically their composition and biosynthetic pathway during cell development, differentiation and oncogenic transformation although they constitute only a small portion of the cell surface glycoconjugates. In addition, acidic GSLs, gangliosides, have been recently shown to exhibit special receptor-functions for exogenous, bioactive factors such as bacterial toxins, hormones and biological response modifiers. We and other investigators have found that human and murine hemopoietic malignant cells show ganglioside-patterns characteristic of their cell lineages and differentiation-stages, serving an differentiation-markers for both normal and malignant hemopoietic cells, and further, discovered that particular ganglioside molecules themselves, which specifically increase during differentiation along particular cell lineages induced by a variety of chemical agents, exhibit remarkably potent differentiation-inducing and growth-inhibitory activities on human myelogenous leukemia cells. On the basis of these findings, some important biological functions of GSLs, especially gangliosides, will be discussed in special reference to hemopoietic cell differentiation.

Animals↗

Association of p93c-fes tyrosine protein kinase with granulocytic/monocytic differentiation and resistance to differentiating agents in HL-60 leukemia cells.

A 93-kDa tyrosine protein kinase (p93) identified previously as the gene product of the c-fes proto-oncogene, is highly expressed in HL-60 leukemia cells induced to differentiate to the granulocyte or monocyte phenotype. We have now studied the relationship of p93 to the differentiation process by using a dimethyl sulfoxide (DMSO)-resistant subline of HL-60 cells (HL-60/DMSO) or the parental cell line treated with peptide or protein substrates of p93. Treatment of HL-60/DMSO cells with DMSO induced neither differentiation nor the expression of p93; however, cotreatment with IFN-alpha and DMSO resulted in partial differentiation and the concomitant induction of p93 activity. Treatment of wild-type HL-60 cells by the coaddition of the p93 substrates poly(Glu,Tyr)1:1, poly(Glu,Tyr)4:1, poly(Glu,Ala,Tyr)6:3:1, angiotensin II or vasoactive intestinal peptide with DMSO or IFN-tau partially blocked differentiation and concurrently diminished the induction of p93 activity. The inhibitory concentrations of the p93 substrates were related to their Km values. These results indicate that there is an obligatory association between the expression of p93 and granulocyte/monocyte differentiation in this cell line.

Cell Differentiation↗

Changes in asparagine-linked sugar chains of human promyelocytic leukemic cells (HL-60) during monocytoid differentiation and myeloid differentiation. Decrease of high-molecular-weight oligosaccharides in acidic fraction.

Asialo-oligosaccharides obtained by sialidase digestion of asparagine-linked acidic sugar chains of promyelocytic leukemic cells (HL-60) differed in size distribution from those of cells induced to undergo myeloid or monocytoid differentiation. High-molecular-weight oligosaccharides which are predominant in HL-60 cells, decreased slightly during myeloid differentiation and markedly during monocytoid differentiation with concomitant increase of biantennary oligosaccharides. Structural analyses revealed that the induced monocytoid cells contain a series of complex-type oligosaccharides with bi-, tri-, and tetraantennary structures and high-molecular-weight oligosaccharides with N-acetyllactosamine repeating units, which show diversity in the presence or absence of the fucose residue linked to the reducing terminal N-acetylglucosamine, of the bisecting N-acetylglucosamine residue, and of the X-antigenic determinant in their outer chain moieties. Methylation analysis of each class of oligosaccharides of HL-60 cells and of their differentiated counterparts revealed the presence of similar heterogeneity in their structures, indicating that the difference is only quantitative. The results show that the shifts in size of the oligosaccharides found in the differentiated cells are derived from changes in outer chain formation and elongation of N-acetyllactosamine repeating units, and thus suggests that the decreased expression of N-acetylglucosaminyltransferases may be involved especially in the monocytoid differentiation program.

Asparagine↗

Differential regulation of the activity of the 42 kD mitogen activated protein kinase (p42mapk) during enterocyte differentiation in vivo.

The family of mitogen activated protein (MAP) kinases appear to play a central role in relaying signals generated by receptor protein tyrosine kinases (RPTK) from the cell surface to the nucleus. We previously demonstrated that undifferentiated and mitotically active crypt cells have high levels of tyrosine phosphorylated proteins (DR Burgess, W Jiang, S Mamajiwalla and W Kinsey. 1989. J. Cell Biol., 109: 2139) possibly due to the activation of RPTKs and also have high pp60c-src protein tyrosine kinase activity (CA Cartwright, SN Mamajiwalla, SA Skolnik, W Eckhart and DR Burgess. 1993. Oncogene. 8: 1033) when compared to differentiated, non-mitotic villus cells. Since activation of RPTKs leading to cell proliferation or differentiation involves activation of the Ras-MAP kinase pathway, we chose to determine in this study if the activity of the MAP kinases were also regulated during differentiation of normal adult enterocytes. Our data show that although the 42 kD MAP kinase (p42mapk) was expressed in both crypt and villus cells, it was phosphorylated on tyrosine and active only in the crypt cells. Our data further suggest that p42mapk is inactivated during differentiation, possibly by a protein tyrosine phosphatase. Immunofluorescence studies revealed that p42mapk localized to the nuclei in both undifferentiated and differentiated enterocytes and colocalized with phosphotyrosine containing proteins at the region of the junctional complex. These results suggest that p42mapk and its regulators are tightly controlled during enterocyte differentiation in vivo and implicate p42mapk as a key regulatory molecule in the normal development of the adult intestinal epithelium.

Animals↗

Differential roles of two types of the TNF receptor in TNF-induced cytotoxicity, DNA fragmentation, and differentiation.

Two different types of TNF receptors, the p60 receptor with a molecular mass of 60 kDa and the p80 receptor with a mass of 80 kDa, have been identified. TNF exhibits a wide variety of biologic actions, but which receptor is responsible for these biologic actions is not well characterized. In the present study, we examined the roles of the p60 and p80 receptors in three different TNF-induced biologic actions: 1) cytotoxicity; 2) DNA fragmentation; and 3) differentiation to macrophages. Analysis of TNF actions on various tumor cell lines revealed that TNF-induced cytotoxicity occurred in cells that expressed the p60 receptor, irrespective of expression of the p80 receptor. In contrast, DNA fragmentation and differentiation were observed only in cells that expressed both receptor types. Additionally, the specific Ab to each receptor were used to examine the roles of both receptors in the myelogenous leukemia cell line, ML-1a. Anti-p60 Ab alone showed cytotoxicity but little DNA fragmentation and differentiation, and anti-p80 Ab alone showed no effects. When these Abs were added in the presence of TNF, each independently, and almost completely, inhibited TNF-induced DNA fragmentation and differentiation. We also found that both Abs together synergistically induce differentiation and DNA fragmentation. These results indicate that signals through the p60 receptor are essential to induce cytotoxicity, but signals through both the p60 and p80 receptors are necessary, and act synergistically, for DNA fragmentation and differentiation.

Cell Differentiation↗

Correct cell- and differentiation-specific expression of a murine alpha 1 (I) collagen minigene in vitro differentiating embryonal carcinoma cells.

An in vitro differentiation system utilizing retinoic acid (RA) treatment of pluripotent murine P19 embryonal carcinoma (EC) cells, which can be induced to differentiate into various cell types, was optimized for maximal induction of alpha 1 type I collagen (Col1a1) gene expression. Differentiation was associated with apoptotic death of the majority of cells, indicating that this in vitro system faithfully mimics the in vivo differentiation process. Col1a1 mRNA became detectable by RNase protection assay after 3 days of RA treatment and, after 6 days, reached a level comparable to that in NIH 3T3 fibroblasts. After induction of differentiation the Col1a1 gene remained transcriptionally active for extended periods of time even in the absence of RA. A minigene version of the murine Col1a1 gene was constructed that contains all of the so far known Col1a1 regulatory elements. This construct exhibited the correct expression pattern in stable transfection experiments: it was expressed in fibroblasts, but not in undifferentiated P19 EC cells, and it was transcriptionally activated after induction of differentiation. This experimental system should be a useful tool for dissecting the molecular mechanisms involved in the developmental activation and stage- and tissue-specific expression of the murine Col1a1 gene.

3T3 Cells↗

Differential regulation of the Wilms' tumor gene, WT1, during differentiation of embryonal carcinoma and embryonic stem cells.

The expression pattern of the Wilms' tumor suppressor gene, WT1, during embryonal development suggests a role for the WT1 proteins in the differentiation of specific tissues. This notion is supported by the observation that WT1 knock-out mice fall to develop kidneys and gonads. We describe here the changes in the expression and DNA binding activity of the WT1 gene product in P19 embryonal carcinoma cells and embryonic stem cells triggered to differentiate by either retinoic acid (RA) or DMSO. In exponentially growing P19 embryonal carcinoma (EC) cells, WT1 mRNA and proteins were undetectable. During RA-induced but not DMSO-induced differentiation of P19 EC cells, WT1 expression and DNA binding are strongly activated. Treatment of embryonic stem cells with RA resulted in a similar activation of WT1. Immunohistochemical analysis showed that WT1 is expressed in endodermal, glial, and epithelial cell types. In addition, DNA binding by EGR-1, a transcription factor structurally related to WT1, increased during differentiation of P19 EC and embryonic stem cells. To investigate the possible functional consequences of DNA binding by WT1, we examined the expression levels of two putative transcriptional targets of WT1, the insulin-like growth factor 1 receptor and epidermal growth factor receptor. We found that after an initial induction, decreasing expression of the insulin-like growth factor I receptor is correlated with increasing WT1 expression. Our results demonstrate that expression of WT1 is induced in specific cell types during RA-induced differentiation of P19 EC cells, reflecting the tissue-specific expression of WT1 in vivo. Therefore, we believe that P19 EC cells are a suitable system to study activation and function of WT1 during differentiation.

Blotting, Western↗

Molecular basis of basal cell carcinoma: analysis of differential gene expression by differential display PCR and expression array.

Basal cell carcinoma (BCC) is the most common tumor in the Caucasian population. Although BCC rarely metastasize and cause death, they are problematic due to their destructive growth and the frequent localization on the face. Until now the knowledge of genes differentially expressed in BCC has been incomplete. To elucidate the complex alterations in BCC-associated gene expression, we took advantage of 2 techniques: the differential display RT-PCR (DD-PCR) and the differential hybridization of cDNA arrays. Using DD-PCR, we showed differential expression of genes known from other biological contexts (e.g., rac, ubiquitin hydrolase), which could now be associated with BCC. In addition, we detected unknown genes possibly contributing to the carcinogenesis of BCC. Of the 588 genes screened by differential hybridization of the Atlas human cDNA array, differences in the expression levels of BCC were observed for 10 genes. These data were obtained with RNA probes pooled from several BCC of different donors and were subsequently confirmed by semiquantitative RT-PCR for Janus protein tyrosine kinase 3 (Jak3), microsomal glutathione S-transferase 1 (GST 12), teratocarcinoma-derived growth factor cripto, glutaredoxin and the monocyte chemoattractant protein 1 (MCP-1) in 10 individual BCC specimens, 2 squamous cell carcinoma (SCC), the cell line HaCaT and cultured normal human keratinocytes (NHK) in comparison to normal skin. These genes are candidates from gene families with known association to tumors, but they have not been reported in the carcinogenesis of BCC yet. In summary, both approaches allow the detection of differentially expressed genes possibly involved in the carcinogenesis of BCC.

Basal Cell Carcinoma↗