Kegg Pathway: Basal transcription factors

J Dermatol Sci. 2009 Nov 13;
Anggakusuma , Yanti , Hwang JK

BACKGROUND: UVB irradiation (290-320nm) is the most damaging component of the UV spectrum and causes both direct and indirect damage to the Basal cell layer of the epidermis; this results in the activation of a number of signaling pathways involved in pathophysiological processes in the skin, such as photoaging and inflammation. In photoaging UVB irradiation promotes degradation of the extracellular matrix (ECM) by matrix metalloproteinases (MMPs) and, in inflammation, UVB irradiation promotes the expression of inducible cyclooxygenase (COX-2), leading to overproduction of inflammatory mediators. OBJECTIVE: We first investigated the protective effects of macelignan from Myristica fragrans Houtt. on immortalized human keratinocytes (HaCaT) against UVB damage. We then explored the inhibitory effects of macelignan on UVB-induced MMP-9 and COX-2 and investigated the molecular mechanism underlying those effects. METHODS: HaCaT cells were treated with macelignan for the indicated times followed by irradiation with UVB. Secretion of MMP-9 was measured by gelatin zymography. Expression of COX-2, mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinase/Akt (PI3K/Akt), c-Fos, c-Jun, and CREB were assayed by western analysis. RESULTS: Macelignan at a concentration of 0.1-1muM increased the viability of HaCaT cells following UVB irradiation and inhibited MMP-9 secretion and COX-2 expression in a concentration-dependent manner. An inhibitory effect was also seen in the signal transduction network, where macelignan treatment reduced the activation of UVB-induced MAPKs, PI3K/Akt, and their downstream transcription factors. CONCLUSION: These results suggest that macelignan protects skin keratinocytes from UVB-induced damage and inhibits MMP-9 and COX-2 expression by attenuating the activation of MAPKs and PI3K/Akt.

Dev Biol. 2009 Nov 12;
Koop D, Holland ND, Sémon M, Alvarez S, Rodriguez de Lera A, Laudet V, Holland LZ, Schubert M

Previous developmental studies of vertebrate development have shown that retinoic acid (RA) signaling at the gastrula stage strongly influences anterior-posterior (A-P) patterning of the neurula and later stages. However, much less is known about the more immediate effects of RA signaling on gene transcription and developmental patterning at the gastrula stage. To investigate the targets of RA signaling during the gastrula stage, we used the Basal chordate amphioxus, in which gastrulation involves very minimal tissue movements. First, we determined the effect of altered RA signaling on expression of 42 genes (encoding transcription factors and components of major signaling cascades) known to be expressed in restricted domains along the A-P axis during the gastrula and early neurula stage. Of these 42 genes, the expression domains during gastrulation of only four (Hox1, Hox3, HNF3-1 and Wnt3) were spatially altered by exposure of the embryos to excess RA or to the RA antagonist BMS009. Moreover, blocking protein synthesis with puromycin before adding RA or BMS009 showed that only three of these genes (Hox1, Hox3 and HNF3-1) are direct RA targets at the gastrula stage. From these results we conclude that in the amphioxus gastrula RA signaling primarily acts via regulation of Hox transcription to establish positional identities along the A-P axis and that Hox1, Hox3, HNF3-1 and Wnt3 constitute a Basal module of RA action during chordate gastrulation.

Ann N Y Acad Sci. 2009 Oct; 1179: 153-66
Chrousos GP, Kino T

Glucocorticoids contribute to the maintenance of Basal and stress-related homeostasis in all higher organisms, and influence a large proportion of the expressed human genome, and their effects spare almost no organs or tissues. Glucocorticoids regulate many functions of the central nervous system, such as arousal, cognition, mood, sleep, the activity and direction of intermediary metabolism, the maintenance of a proper cardiovascular tone, the activity and quality of the immune and inflammatory reaction, including the manifestations of the sickness syndrome, and growth and reproduction. The numerous actions of glucocorticoids are mediated by a set of at least 16 glucocorticoid receptor (GR) isoforms forming homo- or hetero-dimers. The GRs consist of multifunctional domain proteins operating as ligand-dependent transcription factors that interact with many other cell signaling systems, including large and small G proteins. The presence of multiple GR monomers and homo- or hetero-dimers expressed in a cell-specific fashion at different quantities with quantitatively and qualitatively different transcriptional activities suggest that the glucocorticoid signaling system is highly stochastic. Glucocorticoids are heavily involved in human pathophysiology and influence life expectancy. Common behavioral and/or somatic complex disorders, such as anxiety, depression, insomnia, chronic pain and fatigue syndromes, obesity, the metabolic syndrome, essential hypertension, diabetes type 2, atherosclerosis with its cardiovascular sequelae, and osteoporosis, as well as autoimmune inflammatory and allergic disorders, all appear to have a glucocorticoid-regulated component.

Mol Endocrinol. 2009 Nov 6;
Zella LA, Meyer MB, Nerenz RD, Lee SM, Martowicz ML, Pike JW

The vitamin D receptor (VDR) mediates the endocrine actions of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and autoregulates the expression of its own gene in target cells. In studies herein, we used chromatin immunoprecipitation-chip analyses to examine further the activities of 1,25(OH)2D3 and to assess the consequences of VDR/retinoid X receptor heterodimer binding at the VDR gene locus. We also explored mechanisms underlying the ability of retinoic acid, dexamethasone, and the protein kinase A activator forskolin to induce VDR up-regulation as well. We confirmed two previously identified intronic 1,25(OH)2D3-inducible enhancers and discovered two additional regions, one located 6 kb upstream of the VDR transcription start site. Although RNA polymerase II was present at the transcription start site in the absence of 1,25(OH)2D3, it was strikingly up-regulated at both this site and at individual enhancers in its presence. 1,25(OH)2D3 also increased Basal levels of H4 acetylation at these enhancers as well. Surprisingly, many of these enhancers were targets for CCAAT enhancer-binding protein-beta and runt-related transcription factor 2; a subset also bound cAMP response element binding protein, retinoic acid receptor, and glucocorticoid receptor. Unexpectedly, many of these factors were resident at the Vdr gene locus in the absence of inducer, suggesting that they might contribute to Basal Vdr gene expression. Indeed, small interfering RNA down-regulation of CCAAT enhancer-binding protein-beta suppressed Basal VDR expression. These regulatory activities of 1,25(OH)2D3, forskolin, and dexamethasone were recapitulated in MC3T3-E1 cells stably transfected with a full-length VDR bacterial artificial chromosome (BAC) clone-luciferase reporter gene. Finally, 1,25(OH)2D3 also induced accumulation of VDR and up-regulated H4 acetylation at conserved regions in the human VDR gene. These data provide important new insights into VDR gene regulation in bone cells.

Arch Pathol Lab Med. 2009 Nov; 133(11): 1822-5
Kleer CG

This case presentation reviews the histologic distinction between pure medullary carcinoma and breast carcinomas with medullary-like features. This particular case prompts us to analyze the relationship among medullary carcinoma, Basal-like breast carcinomas and carcinomas associated with germline BRCA1 mutations. In addition to now well-defined features, such as expression of high-molecular-weight cytokeratins and EGFR (epidermal growth factor receptor), Basal-like tumors have a deficiency or dysfunction of BRCA1. This association in part explains the histologic features of BRCA1-associated breast cancers. Recent studies in our laboratory demonstrate that BRCA1 protein is regulated by a recently described gene, EZH2. These concepts illustrate the important relationships among histopathologic features; genomic profile; single gene abnormalities, such as BRCA1 and EZH2; and growth regulation in this subset of breast carcinomas.

Mol Biol Cell. 2009 Oct 28;
Xu Y, Baker D, Quan T, Baldassare JJ, Voorhees JJ, Fisher GJ

Monitoring Editor: Jonathan Chernoff Epidermal growth factor receptor (EGFR) signaling pathways promote human keratinocyte survival and proliferation. In contrast, transforming growth factor-beta (TGF-beta) signaling pathways are strongly anti-proliferative. Receptor type protein tyrosine phosphatase-kappa (RPTP-kappa) specifically dephosphorylates EGFR, thereby blocking EGFR-dependent signaling, and inhibiting proliferation. We report here that RPTP-kappa mediates functional integration of EGFR and TGF-beta signaling pathways in human keratinocytes. TGF-beta up-regulates RPTP-kappa mRNA and protein, in a dose and time dependent manner. Induction of RPTP-kappa by TGF-beta significantly decreases Basal and EGF-stimulated EGFR tyrosine phosphorylation. shRNA-mediated reduction of TGF-beta-induced RPTP-kappa significantly attenuates the ability of TGF-beta to inhibit proliferation. RPTP-kappa induction is dependent on activation of transcription factors Smad3 and Smad4. Inhibition of TGF-beta receptor kinase completely prevents induction of RPTP-kappa. Chromatin immunoprecipitation assays reveal that TGF-beta stimulates Smad3 and Smad4 binding to RPTP- kappa gene promoter. Smad3/4 binding is localized to a 186 base pair region, which contains a consensus Smad3 binding element. These data describe a novel mechanism of cross-talk between EGFR and TGF-beta pathways, in which RPTP-kappa functions to integrate growth promoting and growth inhibiting signaling pathways.

Virus Res. 2009 Oct 22;
Wu Y, Tan J, Su Y, Qiao W, Geng Y, Chen Q

Foamy virus contains two promoters, which are the canonical long terminal repeat (LTR) promoter and the internal promoter (IP). FV gene expression was considered to initiate at the internal promoter. However, little was known about how Basal transcription of IP was triggered by the host cellular factors. Previous studies found some cellular proteins could affect HFV viral replication, but it was no known whether the AP1 signal pathway was involved in the activation of viral replication or not. In this study, we reported that treatment with TPA or AP1 increased Basal transcription of IP and did not affect Basal transcription of the promoter in the LTR. In addition, the c-Jun mutant blocked the IP activity stimulated by TPA. Two AP1 binding sites located in BFV-IP promoter were found by bioinformatics and mutants of two AP1 binding sites decreased luciferase reporter activity of IP activated by AP1. EMSA assay showed that two AP1 binding sites could bind to c-Jun/c-Fos heterodimeric. We also found TPA and AP1 enhanced BFV3026 replication. Taken together, these data suggested that AP1 was a positive regulator of BFV internal promoter.

Genome Biol. 2009 Oct 14; 10(10): R113
Xia X, Kung AL

ABSTRACT: BACKGROUND: Hypoxia-inducible factor 1 (HIF-1) plays a key role in cellular adaptation to hypoxia. To better understand the determinants of HIF-1 binding and transactivation, we used ChIP-chip and gene expression profiling to define the relationship between the epigenetic landscape, sites of HIF-1 binding, and genes transactivated by hypoxia in two cell lines. RESULTS: We found that when cells were acutely subjected to hypoxia, HIF-1 preferentially bound to loci that were already transcriptionally active under normal growth conditions characterized by the presence of histone H3 lysine 4 methylation, the presence of RNA polymerase II, and Basal production of mRNA. Cell type-specific differences in HIF-1 binding were largely attributable to differences in the Basal gene expression patterns in the cells prior to the onset of hypoxia. CONCLUSIONS: These results suggest that the repertoire of genes active in a cell (for example, through lineage specific transcription factors) defines the subset of genes that are permissive for binding and transactivation by stimulus-responsive transcription factors.

Gene Expr Patterns. 2009 Dec; 9(8): 555-61
Nelander J, Hebsgaard JB, Parmar M

The neurons in the ventral mesencephalon (VM) are organized into several nuclei consisting of distinct neuronal populations. These include the dopaminergic (DA) neurons of the substania nigra and ventral tegmental area, the oculomotor (OM) neurons that innervate the muscles controlling eye movement, and the reticular neurons of the red nucleus (RN) involved in motor control and coordination reviewed in Puelles (2007). The factors and genes that control the differentiation of the various neuronal populations in the VM have been extensively studied in the mouse and other model organisms but little is known about the progenitors and their protein expression in the developing human brain. In this study we analyze if key regulators identified in rodents are also expressed in the human VM during embryonic development. We report that BLBP and LMX1A mark the floor plate and that FOXA2 is expressed in both the floor plate and Basal plate of the human VM. The proneural transcription factors NGN2 and MASH1 are expressed in the ventricular zone of the human VM within and lateral to the floor plate. The post-mitotic DA neurons express TH as well as NURR1 and PITX3. ISL1 and BRN3A can be used to detect the cells of OM and RN, respectively. We show that many key developmental control factors are expressed in a temporal and spatial manner in the human VM essentially corresponding to what has been observed in the mouse. This data therefore suggest similar roles for these factors also in human VM development and dopamine neurogenesis.

Endocrinology. 2009 Nov; 150(11): 4950-7
Malloy PJ, Wang J, Jensen K, Feldman D

The vitamin D receptor (VDR) and its corepressor Hairless (HR) are thought to regulate key steps in the hair cycle because mutations in VDR or HR cause alopecia in humans and mice. Many mammalian cells express two major HR isoforms due to alternative splicing of exon 17. HR isoform-a encodes an 1189-amino acid protein (full-length HR), and isoform-b encodes an 1134-amino acid protein (HRDelta1072-1126). We demonstrated that both HR isoforms are expressed in primary human keratinocytes and in the human keratinocyte cell line HaCaT. In transfected COS-7 cells, the full-length HR repressed VDR-mediated transactivation. In contrast, HRDelta1072-1126 failed to suppress and even stimulated VDR-mediated transactivation. In coimmunoprecipitation, both HR isoforms interacted with the VDR, but only the full-length HR interacted with histone deacetylase 1 (HDAC1). Alanine mutagenesis of two conserved glutamic acids residues (E1100A/E1101A) encoded by exon 17 completely eliminated HR corepressor activity and interactions with HDAC1. When the two HR isoforms were coexpressed in COS-7 cells, the corepressor activity of the full-length HR was not antagonized by the HRDelta1072-1126 isoform. When transfected into HaCaT cells, the full-length HR inhibited endogenous CYP24A1 Basal gene expression as well as 1,25-dihydroxyvitamin D3-stimulated CYP24A1 expression. HRDelta1072-1126 failed to suppress Basal or 1,25-dihydroxyvitamin D3-stimulated CYP24A1 gene expression. In conclusion, we have demonstrated that both HR isoforms are expressed in keratinocytes and that the HRDelta1072-1126 isoform lacks corepressor activity and is unable to bind HDACs. HRDelta1072-1126 may function as a coactivator in some settings by inhibiting HDAC recruitment to the VDR transcriptional complex.

Protein Expr Purif. 2009 Oct 7;
Yang C, Khaperskyy DA, Hou M, Ponticelli AS

The Basal RNA polymerase II (RNAPII) transcription machinery is composed of RNAPII and the general transcription factors (TF) TATA binding protein (TBP), TFIIB, TFIIE, TFIIF and TFIIH. Due to the powerful genetic and molecular approaches that can be utilized, the budding yeast Saccharomyces cerevisiae has proven to be an invaluable model system for studies of the mechanisms of RNAPII transcription. Complementary biochemical studies of the S. cerevisiae Basal transcription machinery, however, have been hampered by difficulties in the purification of TFIIF and TFIIH, most notably due to the severe toxicity of the TFIIF Tfg1 subunit in Escherichia coli and the complexity of the purification scheme for native TFIIH. Here, we report the elimination of TFG1-associated toxicity in E. coli, the identification and removal of a functional E. coli promoter and internal translation initiation within the N-terminal coding region of TFG1, and the efficient production and two-step purification of recombinant TFIIF complexes. We also report conditions for the efficient two-step tandem affinity purification (TAP) of holo-TFIIH, core TFIIH and TFIIK complexes from yeast whole cell extracts.

Endocr Regul. 2009 Jul; 43(3): 107-16
Coelho DF, Gualano B, Artioli GG, Roschel H, Amano M, Benatti FB, Fernandes T, Bueno CR, Câmara NO, Lancha AH

OBJECTIVE: Since visceral adipose tissue (VAT) may account for impaired peripheral and hepatic insulin sensitivity (IS), it has been hypothesized that the partial removal of VAT could result in improved insulin action, while the re-growth of the excised tissue and/or compensatory growth of non-excised depots seems to occur. Thus, it was aimed to investigate whether or not VAT removal and exercise affect IS. METHODS: Male Wistar rats were fed a high-fat diet and subsequently assigned randomly to one of four groups: 1. exercised plus lipectomized (EL), 2. exercised plus sham-lipectomized (ES), 3. sedentary plus lipectomized (CL), 4. sedentary plus sham-lipectomized (CS). After lipectomy, EL and ES animals underwent a 7-consecutive-day training period. Body weight, food intake, Basal metabolic rate, fasting glucose, and glucose tolerance were assessed before and after the interventions. Fasting insulin and the HOMA index, body fat mass, and the expression of pro-inflammatory genes were assessed after the interventions. RESULTS: EL group showed greater insulin sensitivity compared to all other groups. EL and ES groups showed lower fasting insulin levels when compared to CL and CS groups, respectively. The EL group showed improved IS when compared to the remaining groups. The CL group showed impaired glucose tolerance and increased TNF-alpha gene expression. Body weight and fat mass did not differ among the groups. PPAR gamma gene expression was increased in the EL and ES groups. CONCLUSIONS: These results showed that short-term swimming training improved insulin sensitivity, but failed to prevent fat regain in lipectomized animals. Lipectomy induced impaired glucose tolerance, which is probably related to increased TNF-alpha gene expression. It is possible that a high-fat diet might be implicated in faster regain of adipose tissue after lipectomy. Our results also show that short-term exercise associated with lipectomy could improve insulin sensitivity.

FASEB J. 2009 Oct 7;
Acin-Perez R, Hoyos B, Zhao F, Vinogradov V, Fischman DA, Harris RA, Leitges M, Wongsiriroj N, Blaner WS, Manfredi G, Hammerling U

The physiology of two metabolites of vitamin A is understood in substantial detail: retinaldehyde functions as the universal chromophore in the vertebrate and invertebrate eye; retinoic acid regulates a set of vertebrate transcription factors, the retinoic acid receptor superfamily. The third member of this retinoid triumvirate is retinol. While functioning as the precursor of retinaldehyde and retinoic acid, a growing body of evidence suggests a far more fundamental role for retinol in signal transduction. Here we show that retinol is essential for the metabolic fitness of mitochondria. When cells were deprived of retinol, respiration and ATP synthesis defaulted to Basal levels. They recovered to significantly higher energy output as soon as retinol was restored to physiological concentration, without the need for metabolic conversion to other retinoids. Retinol emerged as an essential cofactor of protein kinase Cdelta (PKCdelta), without which this enzyme failed to be activated in mitochondria. Furthermore, retinol needed to physically bind PKCdelta, because mutation of the retinol binding site rendered PKCdelta unresponsive to Rol, while retaining responsiveness to phorbol ester. The PKCdelta/retinol complex signaled the pyruvate dehydrogenase complex for enhanced flux of pyruvate into the Krebs cycle. The baseline response was reduced in vitamin A-deficient lecithin:retinol acyl transferase-knockout mice, but this was corrected within 3 h by intraperitoneal injection of vitamin A; this suggests that vitamin A is physiologically important. These results illuminate a hitherto unsuspected role of vitamin A in mitochondrial bioenergetics of mammals, acting as a nutritional sensor. As such, retinol is of fundamental importance for energy homeostasis. The data provide a mechanistic explanation to the nearly 100-yr-old question of why vitamin A deficiency causes so many pathologies that are independent of retinoic acid action.-Acin-Perez, T., Hoyos, B., Zhao, F., Vinogradov, V., Fischman, D. A., Harris, R. A., Leitges, M., Wongsiriroj, N., Blaner, W. S., Manfredi, G., Hammerling, U. Control of oxidative phosphorylation by vitamin A illuminates a fundamental role in mitochondrial energy homoeostasis.

Proc Natl Acad Sci U S A. 2009 Sep 22; 106(38): 16434-45
Meechan DW, Tucker ES, Maynard TM, LaMantia AS

The 22q11 deletion (or DiGeorge) syndrome (22q11DS), the result of a 1.5- to 3-megabase hemizygous deletion on human chromosome 22, results in dramatically increased susceptibility for "diseases of cortical connectivity" thought to arise during development, including schizophrenia and autism. We show that diminished dosage of the genes deleted in the 1.5-megabase 22q11 minimal critical deleted region in a mouse model of 22q11DS specifically compromises neurogenesis and subsequent differentiation in the cerebral cortex. Proliferation of Basal, but not apical, progenitors is disrupted, and subsequently, the frequency of layer 2/3, but not layer 5/6, projection neurons is altered. This change is paralleled by aberrant distribution of parvalbumin-labeled interneurons in upper and lower cortical layers. Deletion of Tbx1 or Prodh (22q11 genes independently associated with 22q11DS phenotypes) does not similarly disrupt Basal progenitors. However, expression analysis implicates additional 22q11 genes that are selectively expressed in cortical precursors. Thus, diminished 22q11 gene dosage disrupts cortical neurogenesis and interneuron migration. Such developmental disruption may alter cortical circuitry and establish vulnerability for developmental disorders, including schizophrenia and autism.

Proc Natl Acad Sci U S A. 2009 Oct 13; 106(41): 17314-9
Payankaulam S, Arnosti DN

Despite the pervasive roles for repressors in transcriptional control, the range of action of these proteins on cis regulatory elements remains poorly understood. Knirps has essential roles in patterning the Drosophila embryo by means of short-range repression, an activity that is essential for proper regulation of complex transcriptional control elements. Short-range repressors function in a local fashion to interfere with the activity of activators or Basal promoters within approximately 100 bp. In contrast, long-range repressors such as Hairy act over distances >1 kb. The functional distinction between these two classes of repressors has been suggested to stem from the differential recruitment of the CtBP corepressor to short-range repressors and Groucho to long-range repressors. Contrary to this differential recruitment model, we report that Groucho is a functional part of the Knirps short-range repression complex. The corepressor interaction is mediated via an eh-1 like motif present in the N terminus and a conserved region present in the central portion of Knirps. We also show that this interaction is important for the CtBP-independent repression activity of Knirps and is required for regulation of even-skipped. Our study uncovers a previously uncharacterized interaction between proteins previously thought to function in distinct repression pathways, and indicates that the Groucho corepressor can be differentially harnessed to execute short- and long-range repression.

Acta Pharmacol Sin. 2009 Oct; 30(10): 1369-84
Gordeladze JO, Djouad F, Brondello JM, Noël D, Duroux-Richard I, Apparailly F, Jorgensen C

Bone and cartilage are being generated de novo through concerted actions of a plethora of signals. These act on stem cells (SCs) recruited for lineage-specific differentiation, with cellular phenotypes representing various functions throughout their life span. The signals are rendered by hormones and growth factors (GFs) and mechanical forces ensuring proper modelling and remodelling of bone and cartilage, due to indigenous and programmed metabolism in SCs, osteoblasts, chondrocytes, as well as osteoclasts and other cell types (eg T helper cells).This review focuses on the concerted action of such signals, as well as the regulatory and/or stabilizing control circuits rendered by a class of small RNAs, designated microRNAs. The impact on cell functions evoked by transcription factors (TFs) via various signalling molecules, also encompassing mechanical stimulation, will be discussed featuring microRNAs as important members of an integrative system. The present approach to cell differentiation in vitro may vastly influence cell engineering for in vivo tissue repair.

Reprod Biol Endocrinol. 2009; 7: 106
Penolazzi L, Vecchiatini R, Bignardi S, Lambertini E, Torreggiani E, Canella A, Franceschetti T, Calura G, Vesce F, Piva R

Wharton's jelly from the umbilical cord is a noncontroversial source of mesenchymal stem cells (WJMSCs) with high plasticity, proliferation rate and ability to differentiate towards multiple lineages. WJMSCs from different donors have been characterized for their osteogenic potential. Although there is large evidence of WJMSCs plasticity, recently scientific debate has focused on MSCs selection, establishing predictable elements to discriminate the cells with most promising osteoprogenitor cell potential.In the present study a comparative study between the presence of osteoblastic markers and different parameters that pertain to both the newborn and the mother was performed. Umbilical cords were collected after all patients signed the informed consent and local ethical commettee approved the study. Obstetric parameters, including baby's gender and birth weight, mother's age at delivery, gestational stage at parturition and mode of delivery were examined. After characterization and expansion, WJMSCs were analyzed for two osteoblastic markers, alkaline phosphatase (ALP) activity, and the expression level of RUNX-2 transcription factor, and for their ability to deposit mineralized matrix after osteogenic induction.We found that osteoblastic potential was not influenced by baby's gender and mode of delivery. On the contrary, the highest degree of osteoblastic potential has been shown by WJMSCs with RUNX-2 high Basal levels, selected from umbilical cords of the heaviest term babies.Even if further evaluation is required, our hypothesis is that our findings may help in selecting the optimal umbilical cord donors and in collecting high potential Wharton's jelly-derived osteoprogenitors efficiently.

Biochem J. 2009 Oct 2;
Mojsin M, Stevanovic M

Sox3/SOX3 is considered to be one of the earliest neural markers in vertebrates, playing a role in specifying neuronal fate. We previously reported characterization of the SOX3 promoter and demonstrated that the general transcription factors NF-Y, Sp1 and USF are involved in transcriptional regulation of SOX3 promoter activity. Here we present the first evidence that the TALE transcription factors PBX1 and MEIS1 participate in regulating human SOX3 gene expression in NT2/D1 cells by direct interaction with the consensus Pbx/Meis binding site, which is conserved in all analysed mammalian orthologue promoters. PBX1 is present in the protein complex formed at this site with nuclear proteins from uninduced cells, while both PBX1 and MEIS1 proteins were detected in the complex created with extract from retinoic acid (RA) induced NT2/D1 cells. By functional analysis we also showed that mutations of the Pbx1/Meis1 binding sites resulted in profound reduction of SOX3 promoter responsiveness to RA. Finally, we demonstrated that overexpressed Pbx1 and Meis1 increased endogenous SOX3 protein expression in both uninduced and RA induced NT2/D1 cells. With the data presented here, for the first time, we have established a functional link between the TALE proteins, PBX1 and MEIS1, and expression of the human SOX3 gene. This link is of particular interest since both TALE family members and members of the SOX super-family are recognized as important developmental regulators.

Genes Dev. 2009 Oct 1; 23(19): 2333-44
Buchon N, Broderick NA, Chakrabarti S, Lemaitre B

Gut homeostasis is controlled by both immune and developmental mechanisms, and its disruption can lead to inflammatory disorders or cancerous lesions of the intestine. While the impact of bacteria on the mucosal immune system is beginning to be precisely understood, little is known about the effects of bacteria on gut epithelium renewal. Here, we addressed how both infectious and indigenous bacteria modulate stem cell activity in Drosophila. We show that the increased epithelium renewal observed upon some bacterial infections is a consequence of the oxidative burst, a major defense of the Drosophila gut. Additionally, we provide evidence that the JAK-STAT (Janus kinase-signal transducers and activators of transcription) and JNK (c-Jun NH(2) terminal kinase) pathways are both required for bacteria-induced stem cell proliferation. Similarly, we demonstrate that indigenous gut microbiota activate the same, albeit reduced, program at Basal levels. Altered control of gut microbiota in immune-deficient or aged flies correlates with increased epithelium renewal. Finally, we show that epithelium renewal is an essential component of Drosophila defense against oral bacterial infection. Altogether, these results indicate that gut homeostasis is achieved by a complex interregulation of the immune response, gut microbiota, and stem cell activity.

Neoplasia. 2009 Oct; 11(10): 976-86
Cosse JP, Ronvaux M, Ninane N, Raes MJ, Michiels C

Tumor hypoxia is one of the features of tumor microenvironment that contributes to chemoresistance in particular by cellular adaptations that modulate the apoptotic process. However, the mechanisms involved in this resistance still need deeper understanding. In this study, we investigated the involvement of four transcription factors, c-Myc, nuclear factor kappaB (NF-kappaB), p53, and c-jun/activator protein 1 (AP-1) in the hypoxia-induced resistance to etoposide in HepG2 cells. Whereas the profile of c-Myc and NF-kappaB activity did not fit the effect of hypoxia on caspase 3 activity, hypoxia decreased Basal p53 abundance and DNA binding activity as well as p53 etoposide-induced activation. Short interfering RNA (siRNA) silencing evidenced that p53 was required for etoposide-induced apoptosis under normoxia. An inhibition of its activity under hypoxia could thus be responsible at least in part for the protection observed under hypoxic conditions. Moreover, p53 was found to induce the expression of Bak1. We showed that Bak1 was involved in the etoposide-induced apoptosis because Bak1 siRNA decreased it. Conversely, hypoxia increased c-jun DNA binding activity in the presence of etoposide. siRNA-mediated silencing of c-jun increased the responsiveness of cells to etoposide under hypoxia, as shown by an increase in caspase 3 activity and lactate dehydrogenase release. These effects occurred in a p53-independent manner. These data evidenced that hypoxia decreased the responsiveness of HepG2 cells to etoposide at least by two independent pathways involving p53 inhibition and c-jun activation.