Early Differentiation Genes Research Articles

Early proliferation alteration and differential gene expression in human periodontal ligament cells subjected to cyclic tensile stress

The study was aimed to provide insights into genes governing the early stages of cell proliferation ability alteration and mechano-response in human periodontal ligament cells (PDLCs) induced by short-term cyclic tensile stress. Primary human PDLCs were subjected to cyclic tensile stress (0.5 Hz, 5000 μstrain) for 2h through a four-point bending strain system. After that, cell viability and proliferation ability were examined by MTT [3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and flow cytometry. Furthermore, the gene expression profile was investigated by microarray analysis, and the reliability of which was verified by quantitative RT-PCR. MTT assay and flow cytometry demonstrated that mechanical stress inhibited functional expression and slowed down proliferation of cells. Microarray analysis showed that 110 genes related to cyclic tensile stress were identified in total. Amongst them, ninety-seven were up-regulated, whilst 13 were down-regulated. Eleven genes (KLF10, ETS1, CKS2, DUSP6, KIF23, MAPK6, SERTAD1, IRF1, MAPRE1, CCNB1 and BCAR3) regarding cell cycle arrest were identified. Seven up-regulated genes (PTGS2, KLF10, CDC42EP2, BHLHB2, SPRY2, IER3 and CCL2) were verified by quantitative RT-PCR, which supported the microarray results. Cell cycle arrest and the slow-down proliferation can benefit PDLCs to have more time to respond to mechanical stimuli, and the differential gene expression reflects the behaviour of cells. Those genes in response to cyclic tensile stress were identified in human PDLCs, some of which are related with the mechano-induced cell cycle arrest.

Entamoeba histolytica: Differential gene expression during programmed cell death and identification of early pro- and anti-apoptotic signals

We have demonstrated that programmed cell death (PCD) in Entamoeba histolytica is induced in vitro by G418 aminoglycoside antibiotic. To ascertain if biochemical and morphological changes previously observed are paired to molecular changes that reflect a genetic program, we looked here for early differential gene expression during the induction of PCD. Using cDNA-amplified fragment length polymorphisms (AFLPs) and in silico derived analysis we showed in E. histolytica a differential gene expression during PCD induced by G418. The genes identified encoded for proteins homologous to Glutaminyl-tRNA synthase, Ribosomal Subunit Proteins 40S and 18S, Saposin-like, Silent Information Regulator-2 (Sir-2), and Grainins 1 and 2. Using real-time quantitative PCR (RT Q-PCR), we found that glutaminyl-tRNA synthetase, sir-2, grainins and saposin-like genes were strongly overexpressed after 30 min of PCD induction, while its expression dramatically decreased up to 60 min. On the other hand, overexpression of ribosomal genes increased only 7-fold of basal expression, showing a progressive down-regulation up to 90 min. g lutaminyl-tRNA synthetase, sir-2 and grainins could act as negative regulators of PCD, trying to control the biochemical changes related to PCD activation. Overexpression of saposin-like gene could act as up-regulator of some cell death pathways. Our results give evidence of the first genes identified during the early stage of PCD in E. histolytica that could be implicated in regulation of apoptotic pathways.

Tracing the Derivation of Embryonic Stem Cells from the Inner Cell Mass by Single-Cell RNA-Seq Analysis

SummaryDuring the transition from the inner cell mass (ICM) cells of blastocysts to pluripotent embryonic stem cells (ESCs) in vitro, a normal developmental program is replaced in cells that acquire a capacity for infinite self-renewal and pluripotency. We explored the underlying mechanism of this switch by using RNA-Seq transcriptome analysis at the resolution of single cells. We detected significant molecular transitions and major changes in transcript variants, which include genes for general metabolism. Furthermore, the expression of repressive epigenetic regulators increased with a concomitant decrease in gene activators that might be necessary to sustain the inherent plasticity of ESCs. Furthermore, we detected changes in microRNAs (miRNAs), with one set that targets early differentiation genes while another set targets pluripotency genes to maintain the unique ESC epigenotype. Such genetic and epigenetic events may contribute to a switch from a normal developmental program in adult cells during the formation of diseased tissues, including cancers.

Prenatal Exposure to the Environmental Obesogen Tributyltin Predisposes Multipotent Stem Cells to Become Adipocytes

The environmental obesogen hypothesis proposes that pre- and postnatal exposure to environmental chemicals contributes to adipogenesis and the development of obesity. Tributyltin (TBT) is an agonist of both retinoid X receptor (RXR) and peroxisome proliferator-activated receptor gamma (PPARgamma). Activation of these receptors can elevate adipose mass in adult mice exposed to the chemical in utero. Here we show that TBT sensitizes human and mouse multipotent stromal stem cells derived from white adipose tissue [adipose-derived stromal stem cells (ADSCs)] to undergo adipogenesis. In vitro exposure to TBT, or the PPARgamma activator rosiglitazone increases adipogenesis, cellular lipid content, and expression of adipogenic genes. The adipogenic effects of TBT and rosiglitazone were blocked by the addition of PPARgamma antagonists, suggesting that activation of PPARgamma mediates the effect of both compounds on adipogenesis. ADSCs from mice exposed to TBT in utero showed increased adipogenic capacity and reduced osteogenic capacity with enhanced lipid accumulation in response to adipogenic induction. ADSCs retrieved from animals exposed to TBT in utero showed increased expression of PPARgamma target genes such as the early adipogenic differentiation gene marker fatty acid-binding protein 4 and hypomethylation of the promoter/enhancer region of the fatty acid-binding protein 4 locus. Hence, TBT alters the stem cell compartment by sensitizing multipotent stromal stem cells to differentiate into adipocytes, an effect that could likely increase adipose mass over time.

Prenatal Exposure to the Environmental Obesogen Tributyltin Predisposes Multipotent Stem Cells to Become Adipocytes

The environmental obesogen hypothesis proposes that pre- and postnatal exposure to environmental chemicals contributes to adipogenesis and the development of obesity. Tributyltin (TBT) is an agonist of both retinoid X receptor (RXR) and peroxisome proliferator-activated receptor (PPAR). Activation of these receptors can elevate adipose mass in adult mice exposed to the chemical in utero. Here we show that TBT sensitizes human and mouse multipotent stromal stem cells derived from white adipose tissue [adipose-derived stromal stem cells (ADSCs)] to undergo adipogenesis. In vitro exposure to TBT, or the PPAR activator rosiglitazone increases adipogenesis, cellular lipid content, and expression of adipogenic genes. The adipogenic effects of TBT and rosiglitazone were blocked by the addition of PPAR antagonists, suggesting that activation of PPAR mediates the effect of both compounds on adipogenesis. ADSCs from mice exposed to TBT in utero showed increased adipogenic capacity and reduced osteogenic capacity with enhanced lipid accumulation in response to adipogenic induction. ADSCs retrieved from animals exposed to TBT in utero showed increased expression of PPAR target genes such as the early adipogenic differentiation gene marker fatty acid-binding protein 4 and hypomethylation of the promoter/ enhancer region of the fatty acid-binding protein 4 locus. Hence, TBT alters the stem cell compartment by sensitizing multipotent stromal stem cells to differentiate into adipocytes, an effect that could likely increase adipose mass over time. (Molecular Endocrinology 24: 526–539, 2010)

Initiation of neuronal differentiation requires PI3-kinase/TOR signalling in the vertebrate neural tube

Regulated neuron production within the vertebrate nervous system relies on input from multiple signalling pathways. Work in the Drosophila retina has demonstrated that PI3-kinase and downstream TOR signalling regulate the timing of photoreceptor differentiation; however, the function of such signals during vertebrate neurogenesis is not well understood. Here we show that mutant mice lacking PKB activity downstream of PDK1, the master kinase of the PI3-kinase pathway, exhibit deficient neuron production. We further demonstrate expression of PI3-kinase signalling components and active PKB and TOR signalling in the chick spinal cord, an early site of neurogenesis. Neuron production was also attenuated in the chick neural tube following exposure to small molecule inhibitors of PI3-kinase (LY294002) or TOR (Rapamycin) activity. Furthermore, Rapamycin repressed expression of early neuronal differentiation genes, such as Ngn2, but did not inhibit expression of Sox1B genes characteristic of proliferating neural progenitors. In addition, some cells expressing an early neuronal marker were mis-localised at the ventricular surface in the presence of Rapamycin and remained aberrantly within the cell cycle. These findings suggest that TOR signalling is necessary to initiate neuronal differentiation and that it may facilitate coordination of cell cycle and differentiation programmes. In contrast, stimulating PI3-kinase signalling did not increase neuron production, suggesting that such activity is simply permissive for vertebrate neurogenesis.

Inter-MAR Association Contributes to Transcriptionally Active Looping Events in Human β-globin Gene Cluster

Matrix attachment regions (MARs) are important in chromatin organization and gene regulation. Although it is known that there are a number of MAR elements in the β-globin gene cluster, it is unclear that how these MAR elements are involved in regulating β-globin genes expression. Here, we report the identification of a new MAR element at the LCR(locus control region) of human β-globin gene cluster and the detection of the inter-MAR association within the β-globin gene cluster. Also, we demonstrate that SATB1, a protein factor that has been implicated in the formation of network like higher order chromatin structures at some gene loci, takes part in β-globin specific inter-MAR association through binding the specific MARs. Knocking down of SATB1 obviously reduces the binding of SATB1 to the MARs and diminishes the frequency of the inter-MAR association. As a result, the ACH establishment and the α-like globin genes and β-like globin genes expressions are affected either. In summary, our results suggest that SATB1 is a regulatory factor of hemoglobin genes, especially the early differentiation genes at least through affecting the higher order chromatin structure.

Estrogen treatment up-regulates female genes but does not suppress all early testicular markers during rainbow trout male-to-female gonadal transdifferentiation

In non-mammalian vertebrates, estrogens are key players in ovarian differentiation, but the mechanisms by which they act remain poorly understood. The present study on rainbow trout was designed to investigate whether estrogens trigger the female pathway by activating a group of early female genes (i.e. cyp19a1, foxl2a, foxl2b, fst, bmp4, and fshb) and by repressing early testicular markers (i.e. dmrt1, nr0b1, sox9a1 and sox9a2). Feminization was induced in genetically all-male populations using 17alpha-ethynylestradiol (EE2, 20 mg/kg of food during 2 months). The expression profiles of 100 candidate genes were obtained by real-time RT-PCR and 45 expression profiles displayed a significant differential expression between control populations (males and females) and EE2-treated populations. These expression profiles were grouped in five temporally correlated expression clusters. The estrogen treatment induced most of the early ovarian differentiation genes (foxl2a, foxl2b, fst, bmp4, and fshb) and in particular foxl2a, which was strongly and quickly up-regulated. Simultaneously, Leydig cell genes, involved in androgen synthesis, as well as some Sertoli cell markers (amh, sox9a2) were strongly repressed. However, in contrast to our initial hypothesis, some genes considered as essential for mammalian and fish testis differentiation were not suppressed during the early process of estrogen-induced feminization (dmrt1, nr0b1, sox9a1 and pax2a) and some were even strongly up-regulated (nr0b1, sox9a1and pax2a). In conclusion, estrogens trigger male-to-female transdifferentiation by up-regulating most ovarian specific genes and this up-regulation appears to be crucial for an effective feminization, but estrogens do not concomitantly down-regulate all the testicular differentiation markers.

Quantitative gene expression analysis of pluripotent and early differentiation genes in human preimplantation embryos at the single-cell level

Accurate quantitative measurement of gene expression provides an essential step in understanding the properties and state of blastomeres (BLM). To our knowledge, quantitative measurement of the pluripotency genes Oct4 and NANOG, trophectoderm (Cdx2, HCG), and primitive endoderm (GAT6) in single blastomeres has not been achieved.

Forkhead Proteins Are Critical for Bone Morphogenetic Protein-2 Regulation and Anti-tumor Activity of Resveratrol

Osteoporosis is a major public health problem and the most obvious preventive strategy, hormone replacement therapy, has lost favor due to recent findings of the Women's Health Initiative regarding increased risks of breast cancer and cardiovascular disease. Resveratrol, a naturally occurring compound possessing estrogenic activity, is thought to have considerable potential for therapy of osteoporosis. In the present study, resveratrol was found to exhibit bone-protective effects equivalent to those exerted by hormone replacement therapy and decrease the risk of breast cancer in the in vivo and in vitro models. Forkhead proteins were found to be essential for both effects of resveratrol. The bone-protective effect was attributable to induction of bone morphogenetic protein-2 through Src kinase-dependent estrogen receptor activation and FOXA1 is required for resveratrol-induced estrogen receptor-dependent bone morphogenetic protein-2 expression. The tumor-suppressive effects of resveratrol were the consequence of Akt inactivation-mediated FOXO3a nuclear accumulation and activation. Resveratrol is therefore anticipated to be highly effective in management of postmenopausal osteoporosis without an increased risk of breast cancer.

Hepatic gene induction in murine bone marrow after hepatectomy

Bone marrow cells are highly plastic and differentiate into various cell types, including hepatocytes. To explore the mechanisms underlying these processes, we focused on the initial responses of bone marrow to hepatectomy, using a mouse model. To evaluate hepatic differentiation in bone marrow cells we measured hepatocyte-related gene expression in mice undergoing partial hepatectomy with or without pretreatment for 1 week with 2-acetyl aminofluorene (AAF). Hepatectomy induced several genes related to early hepatic differentiation in bone marrow. Expression of these genes was enhanced by the administration of AAF, whereas genes specific for mature hepatocytes were not detected. We characterised the bone marrow cell population expressing hepatocyte differentiation genes. alpha-fetoprotein mRNA was induced in Lin- and either CD34+, c-kit+, Sca-1+, CD49f+ or CD45+ cells. The genes upregulated in the liver after AAF treatment and hepatectomy were identified using oligonucleotide microarrays. These included genes associated with the acute phase response. Dexamethasone inhibited the expression of early hepatic differentiation genes in the bone marrow of AAF/PHx mice. Early hepatic differentiation genes were induced in bone marrow in response to hepatectomy, especially when regeneration of the remnant liver was suppressed. Circulating signals generated in the AAF/PHx liver might activate this differentiation.

85 Ionizing radiation induces an early differential gene expression profile in normal mouse brain

85 Ionizing radiation induces an early differential gene expression profile in normal mouse brain

Early Differential Gene Expression of Rat Lung after Exposure to Paraquat

Paraquat (PQ), a quaternary nitrogen herbicide, is highly toxic to humans and animals. Acute poisoning and death due to PQ exposure have been reported over the past few decades. Excessive production of oxygen free radicals has been proposed to play an important role in the pulmonary pathology. The aim of the present work was to evaluate the implications for genes that are regulated by oxidative stress at the early stage of PQ exposure in rat lungs. We performed differential display RT-PCR (DD-PCR) on total RNA extracted from rat lungs after injection of 20mg per kg body weight. The experimental DD-PCR conditions, primer length and annealing temperature, were adjusted to improve reproducibility, and 19 differentiated clones were isolated. Sequence analysis followed by conventional RT-PCR and real-time RT-PCR analyses were used to confirm the results. Four clones were finally determined to be significantly affected. These genes were mRNAs for plasma phospholipid transfer protein (PLTP), CL1BA protein, (latrophilin: LPH), and alphaII-spectrin as well as one unknown gene. We demonstrated the distribution of mRNA expression of one gene, LPH, in lung tissues. The present study suggests that 20mg per kg intraperitoneal PQ affects the expression of numerous genes in the lung at 3 h, the onset of pulmonary injury, and that the four genes specified may be major contributors to serious lung injury due to PQ exposure.

Direct interaction of Sox10 with the promoter of murine Dopachrome Tautomerase (Dct) and synergistic activation of Dct expression with Mitf.

The murine dopachrome tautomerase (Dct) gene is expressed early in melanocyte development during embryogenesis, prior to other members of the tyrosinase gene family important for regulating pigmentation. We have used deletion mutants of the Dct promoter, transfections with developmentally relevant transcription factors, and gel shift assays to define transcriptional determinants of Dct expression. Deletion mutagenesis studies show that sequences within the proximal 459 nucleotides are critical for high level expression in melanocytic cells. This region of the promoter contains candidate binding sites for the transcription factors Sox10 and Mitf. Transfections into 293T and NIH3T3 cells show that Sox10 and Mitf independently activate Dct expression, and, when co-transfected, synergistically activate Dct expression. To support the notion that Sox10 acts directly upon the Dct promoter to activate gene expression, direct interaction of Sox10 was demonstrated using gel shifts of oligonucleotide probes derived from promoter sequences within the region required for Sox10-dependent induction. These results suggest that a combinatorial transcription factor interaction is important for expression of Dct in neural crest-derived melanocytes, and support a model for sequential gene activation in melanocyte development whereby Mitf, a Sox10-dependent transcription factor, is expressed initially before an early melanocyte differentiation gene, Dct, is expressed.

Diurnal expression of hetR and diazocyte development in the filamentous non-heterocystous cyanobacterium Trichodesmium erythraeum.

The marine non-heterocystous cyanobacterium Trichodesmium fixes atmospheric N(2) aerobically in light. In situ immunolocalization/light microscopy of NifH revealed that lighter, non-granulated cell regions observed correspond to the nitrogenase-containing diazocyte clusters in Trichodesmium IMS101. The number of diazocyte clusters per trichome varied from 0 to 4 depending on trichome length. The constant percentage of diazocytes (approx. 15 %) in cultured strains and five natural populations suggests a developmentally regulated differentiation process. Real-time RT-PCR showed that ntcA, encoding the global nitrogen regulator in cyanobacteria, and hetR, the key regulatory gene in heterocyst differentiation, are both constitutively expressed during a 12 h/12 h light/dark cycle. hetR in addition showed a distinct peak in the dark (close to midnight) while nifH expression commenced 6-8 h later. The expression of all three genes was negatively affected by addition of ammonia. Some early heterocyst differentiation genes were also identified in the genome of Trichodesmium. The data suggest that hetR and ntcA may be required for development and function of diazocytes in Trichodesmium.

Gene expression profiling of human plasma cell differentiation and classification of multiple myeloma based on similarities to distinct stages of late-stage B-cell development

AbstractTo identify genes linked to normal plasma cell (PC) differentiation and to classify multiple myeloma (MM) with respect to the expression patterns of these genes, we analyzed global mRNA expression in CD19-enriched B cells (BCs) from 7 tonsils, CD138-enriched PCs from 11 tonsils, 31 normal bone marrow samples, and 74 MM bone marrow samples using microarrays interrogating 6800 genes. Hierarchical clustering analyses with 3288 genes clearly segregated the 4 cell types, and chi-square and Wilcoxin rank sum tests (P < .0005) identified 359 and 500 previously defined and novel genes that distinguish tonsil BCs from tonsil PCs (early differentiation genes [EDGs]), and tonsil PCs from bone marrow PCs (late differentiation genes [LDGs]), respectively. MM as a whole was found to have dramatically variable expression of EDGs and LDGs, and one-way analysis of variance (ANOVA) was used to identify the most variable EDGs (vEDGs) and LDGs (v1LDG and v2LDG). Hierarchical cluster analysis with these genes revealed that previously defined MM gene expression subgroups (MM1-MM4) could be linked to one of the 3 normal cell types. Clustering with 30 vEDGs revealed that 13 of 18 MM4 cases clustered with tonsil BCs (P = .000 05), whereas 14 of 15 MM3 cases clustered with tonsil PCs when using 50 v1LDG (P = .000 008), and 14 of 20 MM2 cases clustered with bone marrow PCs when using 50 v2LDG (P = .000 09). MM1 showed no significant linkage with normal cell types studied. Thus, genes whose expression is linked to distinct transitions in late-stage B-cell differentiation can be used to classify MM.

Distinct Mechanisms Triggering Glial Differentiation in Drosophila Thoracic and Abdominal Neuroblasts 6-4

Neurons and glia are produced in stereotyped patterns after neuroblast cell division during development of the Drosophila central nervous system. The first cell division of thoracic neuroblast 6-4 (NB6-4T) is asymmetric, giving rise to a glial precursor cell and a neuronal precursor cell. In contrast, abdominal NB6-4 (NB6-4A) divides symmetrically to produce two glial cells. To understand the relationship between cell division and glia–neuron cell fate determination, we examined and compared the effects of known cell division mutations on the NB6-4T and NB6-4A lineages. Based on observation of expression of glial fate determination and early glial differentiation genes, the onset of glial differentiation occurred in NB6-4A but not in NB6-4T when both cell cycle progression and cytokinesis were genetically arrested. On the other hand, glial differentiation started in both lineages when cytokinesis was blocked with intact cell cycle progression. These results showed that NB6-4T, but not NB6-4A, requires cell cycle progression for acquisition of glial fate, suggesting that distinct mechanisms trigger glial differentiation in the different lineages.