Exogenous modification of EL-4 T cell extracellular vesicles with miR-155 induce macrophage into M1-type polarization

Extracellular vesicles (EVs) show promising potential to be used as therapeutics, disease biomarkers, and drug delivery vehicles. We aimed to modify EVs with miR-155 to modulate macrophage immune response that can be potentially used against infectious diseases. Primarily, we characterized T cells (EL-4) EVs by several standardized techniques and confirmed that the EVs could be used for experimental approaches. The bioactivities of the isolated EVs were confirmed by the uptake assessment, and the results showed that target cells can successfully uptake EVs. To standardize the loading protocol by electroporation for effective biological functionality, we chose fluorescently labelled miR-155 mimics because of its important roles in the immune regulations to upload them into EVs. The loading procedure showed that the dosage of 1 µg of miRNA mimics can be efficiently loaded to the EVs at 100 V, further confirmed by flow cytometry. The functional assay by incubating these modified EVs (mEVs) with in vitro cultured cells led to an increased abundance of miR-155 and decreased the expressions of its target genes such as TSHZ3, Jarid2, ZFP652, and WWC1. Further evaluation indicated that these mEVs induced M1-type macrophage polarization with increased TNF-α, IL-6, IL-1β, and iNOS expression. The bioavailability analysis revealed that mEVs could be detected in tissues of the livers. Overall, our study demonstrated that EVs can be engineered with miR-155 of interest to modulate the immune response that may have implications against infectious diseases.

Quercetin improves epithelial regeneration from airway basal cells of COPD patients

BACKGROUND

Airway basal cells (BC) from patients with chronic obstructive pulmonary disease (COPD) regenerate abnormal airway epithelium and this was associated with reduced expression of several genes involved in epithelial repair. Quercetin reduces airway epithelial remodeling and inflammation in COPD models, therefore we examined whether quercetin promotes normal epithelial regeneration from COPD BC by altering gene expression.

METHODS

COPD BC treated with DMSO or 1 µM quercetin for three days were cultured at air/liquid interface (ALI) for up to 4 weeks. BC from healthy donors cultured at ALI were used as controls. Polarization of cells was determined at 8 days of ALI. The cell types and IL-8 expression in differentiated cell cultures were quantified by flow cytometry and ELISA respectively. Microarray analysis was conducted on DMSO or 1 µM quercetin-treated COPD BC for 3 days to identify differentially regulated genes (DEG). Bronchial brushings obtained from COPD patients with similar age and disease status treated with either placebo (4 subjects) or 2000 mg/day quercetin (7 subjects) for 6 months were used to confirm the effects of quercetin on gene expression.

RESULTS

Compared to placebo-, quercetin-treated COPD BC showed significantly increased transepithelial resistance, more ciliated cells, fewer goblet cells, and lower IL-8. Quercetin upregulated genes associated with tissue and epithelial development and differentiation in COPD BC. COPD patients treated with quercetin, but not placebo showed increased expression of two developmental genes HOXB2 and ELF3, which were also increased in quercetin-treated COPD BC with FDR < 0.001. Active smokers showed increased mRNA expression of TGF-β (0.067) and IL-8 (22.0), which was reduced by 3.6 and 4.14 fold respectively after quercetin treatment.

CONCLUSIONS

These results indicate that quercetin may improve airway epithelial regeneration by increasing the expression of genes involved in epithelial development/differentiation in COPD.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov on 6-18-2019. The study number is NCT03989271.

Neuroprotective effect of the PACAP-ADNP axis on SOD1G93A mutant motor neuron death induced by trophic factors deprivation

Amyotrophic lateral Sclerosis (ALS) is a neurodegenerative disease characterized by progressive degeneration of motor neurons in the central nervous system. Mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1) account for approximately in 20% of familial ALS cases. The pathological mechanisms underlying the toxicity induced by mutated SOD1 are still unknown. However, it has been hypothesized that oxidative stress (OS) has a crucial role in motor neuron degeneration in ALS patients. Moreover, it has been described that SOD1 mutation interferes expression of nuclear factor erythroid 2-related factor 2 (Nrf2), a protective key modulator against OS and reactive oxygen species (ROS) formation. The protective effect of pituitary adenylate cyclase-activating peptide (PACAP) has been demonstrated in various neurological disorders, including ALS. Some of its effects are mediated by the stimulation of an intracellular factor known as activity-dependent protein (ADNP). The role of PACAP-ADNP axis on mutated SOD1 motor neuron degeneration has not been explored, yet. The present study aimed to investigate whether PACAP prevented apoptotic cell death induced by growth factor deprivation through ADNP activation and whether the peptidergic axis can counteract the OS insult. By using an in vitro model of ALS, we demonstrated that PACAP by binding to PAC1 receptor (PAC1R) prevented motor neuron death induced by serum deprivation through induction of the ADNP expression via PKC stimulation. Furthermore, we have also demonstrated that the PACAP/ADNP axis counteracted ROS formation by inducing translocation of the Nfr2 from the cytoplasm to the nucleus. In conclusion, our study provides new insights regarding the protective role of PACAP-ADNP in ALS.

Kaempferol counteracts toxicity induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in D. melanogaster: An implication of its mitoprotective activity

The current study aimed to investigate whether kaempferol (KMP), the major bioactive component of green leafy vegetables, could counteract the toxicity elicited by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in Drosophila melanogaster or not. First, we performed a dose-response curve, where adult wild-type flies were fed on diet-containing different concentrations of KMP throughout their lifespan. Afterward, flies were fed on a diet containing MPTP (500 μM) and KMP (20 and 40 μM) for 7 days. The MPTP- fed flies presented a higher mortality rate, lower emergence rate, locomotor deficits, and disruption in circadian rhythm when compared to the control. MPTP exposure induced severe oxidative stress, which was marked by reduction in thiol content, overproduction of reactive species, lipid and protein oxidation, and disruption of enzymes of antioxidant and neurotransmission pathways. MPTP also compromised the mitochondrial dynamics and respiration of flies, affecting the electron transport chain, oxidative phosphorylation, and fusion/fission processes. Besides extending per se the lifespan of flies, KMP counteracted the toxic effects of MPTP on the circadian cycle, survival, climbing, and hatching rates. KMP was also effective in restoring the activities of acetylcholinesterase (AChE) and monoamine oxidase (MAO) enzymes, as well as in normalizing the levels of all oxidant/antioxidant markers disrupted in MPTP-fed flies. Indeed, KMP reestablished the mitochondrial functionality in MPTP- fed flies, restoring the electron transport system linked to mitochondrial complex I and II, and rescuing the mRNA transcription of genes associated with mitochondrial fusion and fission, namely OPA-1 (Optic atrophy 1) and DRP-1 (Dynamin related protein 1). Our results showed the efficacy of KMP in hindering the toxicity induced by MPTP in D. melanogaster and suggest that the mitoprotective action of flavonoid may be boosting its anti-parkinsonism activity in the model. Besides, the study showed that wild-type strains of D. melanogaster proved to be reproducible in vivo model to mimic parkinsonian phenotypes through exposure to the neurotoxin MPTP.

HOXB9 Overexpression Confers Chemoresistance to Ovarian Cancer Cells by Inducing ERCC-1, MRP-2, and XIAP

The purpose of this study was to identify the role of HOXB9 and associated molecular mechanism in acquiring chemoresistance to ovarian cancer cells. After establishing HOXB9-overexpressing cells (HOXB9-OE/SKOV3), cisplatin resistance-induced cells (Cis-R/SKOV3), and an ovarian cancer xenograft mouse model, the effects of HOXB9 were evaluated in vitro and in vivo. Expression levels of ERCC-1, MRP-2, XIAP, and Bax/Bcl-2 were assessed as putative mechanisms mediating chemoresistance. Cisplatin-induced apoptosis was significantly decreased in HOXB9-OE/SKOV3 compared to SKOV3. Cisplatin treatment of SKOV3 strongly induced ERCC-1, MRP-2, and XIAP, and apoptosis was strongly induced through the inhibition of Bcl-2 and activation of Bax. ERCC-1, MRP-2, XIAP, and Bcl-2 were also strongly induced in HOXB9 OE/SKOV3. In contrast to SKOV3, cisplatin treatment alone of HOXB9 OE/SKOV3 did not affect the expression of Bcl-2 and Bax, and consequently, there was no increase in apoptosis. HOXB9 knockdown suppressed the expression of ERCC-1 and XIAP, but did not affect MRP-2 and Bcl-2/Bax expression in HOXB9 OE/SKOV3 and Cis-R/SKOV3, and caused a small increase in apoptosis. Treatment of SKOV3 with both cisplatin and siRNA_HOXB9 led to complete suppression of ERCC-1, MRP-2, and XIAP, and significantly increased apoptosis through inhibition of Bcl-2 expression and activation of Bax. The results observed in Cis-R/SKOV3 were similar to that in HOXB9 OE/SKOV3. Our data suggest that HOXB9 overexpression may cause chemoresistance in ovarian cancer cells by differential induction of ERCC-1, MRP-2, and XIAP depending on the strength of HOXB9 expression through inhibition of the mitochondrial pathway of apoptosis, including Bax/Bcl-2.

PKNOX1 acts as a transcription factor of DHH and promotes the progression of stomach adenocarcinoma by regulating the Hedgehog signalling pathway

BACKGROUND

This study explored the effects and potential mechanism by which PBX/knotted 1 homeobox 1 (PKNOX1) may exacerbate stomach adenocarcinoma (STAD).

METHODS

For the in silico analysis, we examined TCGA-PKNOX1 expression using the UALCAN website, as well as its expression patterns in the GSE172032 and GSE174237 datasets, obtained from the GEO database. The associated patient survival curves, were analysed via the KMplot webtool. In vitro, we measured cell viability, proliferation, migration, and invasion using cell counting kit-8, colony formation, wound healing, and cell migration assays, respectively. Real time qPCR and western blotting assessed the mRNA and protein levels of PKNOX1, Snail, vimentin, N-cadherin, E-cadherin, desert hedgehog (DHH), cyclin D2, glioma-associated oncogene homolog 1, and smoothened. Gene Set Enrichment Analysis was performed using LinkedOmics webtools and the clusterProfiler package in R. Dual-luciferase reporter assay was used to examine the interactions of PKNOX1 with DHH, and of TEA domain transcription factor 4 (TEAD4) with PKNOX1.

RESULTS

PKNOX1 was highly expressed in STAD and linked to poor patient survival. Downregulation of PKNOX1 inhibited STAD cell viability, proliferation, migration, invasion, and epithelial-mesenchymal transition. Upregulation of TEAD4 promoted colony formation and migration, while these effects were reversed by PKNOX1 depletion. Furthermore, PKNOX1 regulated the activation of the hedgehog signalling pathway at the gene level, as we identified PKNOX1 to be a putative transcription factor for DHH that promotes its expression.

CONCLUSION

Our results show that PKNOX1 acts as a candidate transcription factor for DHH and facilitates STAD development by regulating the hedgehog signalling pathway.

BDE-99 Disrupts the Photoreceptor Patterning of Zebrafish Larvae via Transcription Factor six7

Proper visual function is essential for collecting environmental information and supporting the decision-making in the central nervous system and is therefore tightly associated with wildlife survival and human health. Polybrominated diphenyl ethers (PBDEs) were reported to impair zebrafish vision development, and thyroid hormone (TH) signaling was suspected as the main contributor. In this study, a pentabrominated PBDE, BDE-99, was chosen to further explore the action mechanism of PBDEs on the disruption of zebrafish color vision. The results showed that BDE-99 could impair multiple photoreceptors in the retina and disturb the behavior guided by the color vision of zebrafish larvae at 120 h post-fertilization. Although the resulting alteration in photoreceptor patterning highly resembled the effects of 3,3',5-triiodo-l-thyroine, introducing the antagonist for TH receptors was unable to fully recover the alteration, which suggested the involvement of other potential regulatory factors. By modulating the expression of six7, a key inducer of middle-wavelength opsins, we demonstrated that six7, not THs, dominated the photoreceptor patterning in the disruption of BDE-99. Our work promoted the understanding of the regulatory role of six7 in the process of photoreceptor patterning and proposed a novel mechanism for the visual toxicity of PBDEs.

Analysis of Early Cone Dysfunction in an In Vivo Model of Rod-Cone Dystrophy

Retinitis pigmentosa (RP) is a generic term for a group of genetic diseases characterized by loss of rod and cone photoreceptor cells. Although the genetic causes of RP frequently only affect the rod photoreceptor cells, cone photoreceptors become stressed in the absence of rods and undergo a secondary degeneration. Changes in the gene expression profile of cone photoreceptor cells are likely to occur prior to observable physiological changes. To this end, we sought to achieve greater understanding of the changes in cone photoreceptor cells early in the degeneration process of the Rho^−/− mouse model. To account for gene expression changes attributed to loss of cone photoreceptor cells, we normalized PCR in the remaining number of cones to a cone cell reporter (OPN1-GFP). Gene expression profiles of key components involved in the cone phototransduction cascade were correlated with tests of retinal cone function prior to cell loss. A significant downregulation of the photoreceptor transcription factor Crx was observed, which preceded a significant downregulation in cone opsin transcripts that coincided with declining cone function. Our data add to the growing understanding of molecular changes that occur prior to cone dysfunction in a model of rod-cone dystrophy. It is of interest that gene supplementation of CRX by adeno-associated viral vector delivery prior to cone cell loss did not prevent cone photoreceptor degeneration in this mouse model.

Effect of Recombinant Human Pentraxin 2 vs Placebo on Change in Forced Vital Capacity in Patients With Idiopathic Pulmonary Fibrosis: A Randomized Clinical Trial

IMPORTANCE

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with poor prognosis. Approved therapies do not halt disease progression.

OBJECTIVE

To determine the effect of recombinant human pentraxin 2 vs placebo on change from baseline to week 28 in mean forced vital capacity (FVC) percentage of predicted value.

DESIGN, SETTING, AND PARTICIPANTS

Phase 2, randomized, double-blind, placebo-controlled trial conducted at 18 sites in 7 countries of eligible patients with IPF (N = 117; aged 40-80 years; FVC ≥50% and ≤90% predicted; ratio of forced expiratory volume in the first second/FVC >0.70; diffusing capacity for carbon monoxide [Dlco] ≥25% and ≤90% predicted; and distance of ≥150 m on the 6-minute walk test). Study period was August 2015-May 2017.

INTERVENTIONS

Patients were randomized to receive either recombinant human pentraxin 2 (10 mg/kg intravenous every 4 weeks, n = 77) or placebo (n = 39) for 24 weeks, and stratified by concurrent IPF treatment status.

MAIN OUTCOMES AND MEASURES

The primary end point was the least-squares mean change in FVC percentage of predicted value from baseline to week 28 (minimal clinically important difference, decline of 2%-6%). Secondary end points included mean change in lung volumes (total, normal, and interstitial lung abnormalities) on high-resolution computed tomography (HRCT) and 6-minute walk distance (minimal clinically important difference, 24-45 m).

RESULTS

Of 117 randomized patients, 116 received at least 1 dose of study drug (mean age, 68.6 years; 81.0% men; mean time since IPF diagnosis, 3.8 years), and 111 (95.7%) completed the study. The least-squares mean change in FVC percentage of predicted value from baseline to week 28 in patients treated with recombinant human pentraxin 2 was -2.5 vs -4.8 for those in the placebo group (difference, +2.3 [90% CI, 1.1 to 3.5]; P = .001). No significant treatment differences were observed in total lung volume (difference, 93.5 mL [90% CI, -27.7 to 214.7]), quantitative parenchymal features on HRCT (normal lung volume difference, -1.2% [90% CI, -4.4 to 1.9]; interstitial lung abnormalities difference, 1.1% [90% CI, -2.2 to 4.3]), or measurement of Dlco (difference, -0.4 [90% CI, -2.6 to 1.7]). The change in 6-minute walk distance was -0.5 m for patients treated with recombinant human pentraxin 2 vs -31.8 m for those in the placebo group (difference, +31.3 m [90% CI, 17.4 to 45.1]; P < .001). The most common adverse events in the recombinant human pentraxin 2 vs placebo group were cough (18% vs 5%), fatigue (17% vs 10%), and nasopharyngitis (16% vs 23%).

CONCLUSIONS AND RELEVANCE

In this preliminary study, recombinant human pentraxin 2 vs placebo resulted in a slower decline in lung function over 28 weeks for patients with idiopathic pulmonary fibrosis. Further research should more fully assess efficacy and safety.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02550873.

Promotion of LncRNA HOXA11-AS on the proliferation of hepatocellular carcinoma by regulating the expression of LATS1

OBJECTIVE

To investigate the expression levels of lncRNA HOXA11-AS in HCC tissues and cells, and to explore its biological role in the development and progression of HCC.

PATIENTS AND METHODS

We detected the relative expression level of HOXA11-AS in 72 HCC tissues and cells by the real-time quantitative PCR (qRT-PCR) assay. After interference with HOXA11-AS expression in HCC cells, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), clone formation, flow cytometry and an established nude mice transplanted tumor model were used to detect the biological behavior of HCC cells. qRT-PCR and Western blotting assays were used to detect the expression level of large tumor suppressor kinases 1 (LATS1). The subcellular localization of HOXA11-AS in HCC was detected by separating nuclei from the cytoplasm. The molecular mechanism of HOXA11-AS was regulated by ribonucleoprotein immunoprecipitation-microarray (RIP-Chip) experiments.

RESULTS

qRT-PCR assays showed that HOXA11-AS was relatively highly expressed in HCC tissues and cells. In vivo and in vitro experiments showed that HOXA11-AS could inhibit the proliferation of HCC cells, promote their apoptosis and retard the cell cycle progression from G1 to G0 phase. qRT-PCR and Western blotting assays results showed that LATS1 genes were the downstream target genes of HOXA11-AS. RIP and CHIP experiments showed that HOXA11-AS inhibited the expression of LATS1 genes by binding enhancer of zeste homolog 2 (EZH2) proteins.

CONCLUSIONS

HOXA11-AS inhibited the malignant transcription of the LATS1 genes and promoted the malignant proliferation of HCC cells. Interactions among HOXA11-AS, PRC2, and LATS1 may provide a new target for the treatment of HCC.

Cell-Penetrating Peptide as a Means of Directing the Differentiation of Induced-Pluripotent Stem Cells

Protein transduction using cell-penetrating peptides (CPPs) is useful for the delivery of large protein molecules, including some transcription factors. This method is safer than gene transfection methods with a viral vector because there is no risk of genomic integration of the exogenous DNA. Recently, this method was reported as a means for the induction of induced pluripotent stem (iPS) cells, directing the differentiation into specific cell types and supporting gene editing/correction. Furthermore, we developed a direct differentiation method to obtain a pancreatic lineage from mouse and human pluripotent stem cells via the protein transduction of three transcription factors, Pdx1, NeuroD, and MafA. Here, we discuss the possibility of using CPPs as a means of directing the differentiation of iPS cells and other stem cell technologies.

Adult Human Biliary Tree Stem Cells Differentiate to β-Pancreatic Islet Cells by Treatment with a Recombinant Human Pdx1 Peptide

Generation of β-pancreatic cells represents a major goal in research. The aim of this study was to explore a protein-based strategy to induce differentiation of human biliary tree stem cells (hBTSCs) towards β-pancreatic cells. A plasmid containing the sequence of the human pancreatic and duodenal homeobox 1 (PDX1) has been expressed in E. coli. Epithelial-Cell-Adhesion-Molecule positive hBTSCs or mature human hepatocyte cell line, HepG2, were grown in medium to which Pdx1 peptide was added. Differentiation toward pancreatic islet cells were evaluated by the expression of the β-cell transcription factors, Pdx1 and musculoapo-neurotic fibrosarcoma oncogene homolog A, and of the pancreatic hormones, insulin, glucagon, and somatostatin, investigated by real time polymerase chain reaction, western blot, light microscopy and immunofluorescence. C-peptide secretion in response to high glucose was also measured. Results indicated how purified Pdx1 protein corresponding to the primary structure of the human Pdx1 by mass spectroscopy was efficiently produced in bacteria, and transduced into hBTSCs. Pdx1 exposure triggered the expression of both intermediate and mature stage β-cell differentiation markers only in hBTSCs but not in HepG2 cell line. Furthermore, hBTSCs exposed to Pdx1 showed up-regulation of insulin, glucagon and somatostatin genes and formation of 3-dimensional islet-like structures intensely positive for insulin and glucagon. Finally, Pdx1-induced islet-like structures exhibited glucose-regulated C-peptide secretion. In conclusion, the human Pdx1 is highly effective in triggering hBTSC differentiation toward functional β-pancreatic cells.

Exploiting the TRIP-Br family of cell cycle regulatory proteins as chemotherapeutic drug targets in human cancer

TRIP-Br1 and TRIP-Br2 are potent cell growth promoting factors that function as components of the E2F1/DP1 transcription complex to integrate positive growth signals provided by PHD zinc finger- and/or bromodomain-containing transcription factors. TRIP-Br1 has been demonstrated to be an oncogene. We recently reported that antagonism of the TRIP-Br integrator function by synthetic decoy peptides that compete with TRIP-Br for binding to PHD zinc finger- and/or bromodomain-containing proteins elicit an anti-proliferative effect and induces caspase-3-independent sub-diploidization in cancer cells in vitro. We now demonstrate the chemotherapeutic potential of TRIP-Br decoy peptides for the treatment of cutaneous and intracavitary lesions in vitro as well as in vivo in representative human nasopharyngeal cancer (CNE2), cervical cancer (Ca Ski) and melanoma (MeWo) cancer cell lines. In vitro, BrdU incorporation, colony formation assays and cell cycle analysis confirmed that TRIP-Br decoy peptides possess strong anti-proliferative effects and induce nuclear sub-diploidization in cancer cells. In vivo, CNE2, Ca Ski and MeWo-derived chick embryo chorioallantoic membrane (CAM) tumor xenografts were used to evaluate the effect of topically applied TRIP-Br peptides. Confocal microscopy and flow cytometric analysis demonstrated that cells comprising the tumor xenografts efficiently internalized topically applied FITC-labeled peptides. Fifty muM of TRIP-Br1 decoy peptide significantly suppressed the growth of NPC2-derived human nasopharyngeal tumors, while 50 muM of TRIP-Br2 decoy peptide significantly inhibited tumor growth in all three CAM tumor xenograft models. Two hundred muM of TRIP-Br1 decoy peptide significantly inhibited MeWo-derived tumors. These results suggest that the TRIP-Br integrator function may represent a novel chemotherapeutic target for the treatment of human cutaneous and intracavitary proliferative lesions.

Targeted induction of endogenous NKX3-1 by small activating RNA inhibits prostate tumor growth

BACKGROUND

RNA activation (RNAa) is a small RNA-mediated gene regulation mechanism by which expression of a particular gene can be induced by targeting its promoter using small double-stranded RNA also known as small activating RNA (saRNA). We used saRNA as a molecular tool to examine NKX3-1's role as a tumor suppressor and tested in vitro and in vivo antitumor effects of NKX3-1 induction by saRNA.

MATERIALS AND METHODS

NKX3-1 saRNA was transfected into human prostate cancer cells including LNCaP, CWR22R, PC-3, CWR22RV1, DuPro, LAPC4, and DU145. The transfected cells were used for analysis of gene expression by RT-PCR and immunoblotting, proliferation, apoptosis and cell cycle distribution. PC-3 xenograft models were established in immunocompromised mice and treated with NKX3-1 saRNA.

RESULTS

NKX3-1 saRNA induced NKX3-1 expression in different prostate cancer cell lines, resulting in inhibited cell proliferation and survival, cell cycle arrest and apoptotic cell death. These effects were partly mediated by NKX3-1's regulation of several downstream genes including the upregulation of p21 and p27, and the inhibition of VEGFC expression. Treatment of mouse xenograft prostate tumors with intratumoral delivery of NKX3-1 saRNA formulated in lipid nanoparticles significantly inhibited tumor growth and prolonged animal survival.

CONCLUSIONS

By revealing several important target genes of NKX3-1, our findings corroborated NKX3-1's role as a tumor suppressor gene through direct regulation of the cell cycle and growth/survival pathways. This study also validated the therapeutic potential of saRNA for the treatment of prostate cancer via targeted activation of tumor suppressor genes.

Six1 promotes proliferation of pancreatic cancer cells via upregulation of cyclin D1 expression

Six1 is one of the transcription factors that act as master regulators of development and are frequently dysregulated in cancers. However, the role of Six1 in pancreatic cancer is not clear. Here we show that the relative expression of Six1 mRNA is increased in pancreatic cancer and correlated with advanced tumor stage. In vitro functional assays demonstrate that forced overexpression of Six1 significantly enhances the growth rate and proliferation ability of pancreatic cancer cells. Knockdown of endogenous Six1 decreases the proliferation of these cells dramatically. Furthermore, Six1 promotes the growth of pancreatic cancer cells in a xenograft assay. We also show that the gene encoding cyclin D1 is a direct transcriptional target of Six1 in pancreatic cancer cells. Overexpression of Six1 upregulates cyclin D1 mRNA and protein, and significantly enhances the activity of the cyclin D1 promoter in PANC-1 cells. We demonstrate that Six1 promotes cell cycle progression and proliferation by upregulation of cyclin D1. These data suggest that Six1 is overexpressed in pancreatic cancer and may contribute to the increased cell proliferation through upregulation of cyclin D1.

Cytotoxic activity to acute myeloid leukemia cells by Antp-TPR hybrid peptide targeting Hsp90

We previously reported that Antp-TPR hybrid peptide inhibited the interaction of Hsp90 with TPR2A and had selective cytotoxic activity discriminating between normal and cancer cells to induce cancer cell death. In this study, we investigated the cytotoxic activity of Antp-TPR peptide toward acute myeloid leukemia (AML) cells. It was demonstrated that Antp-TPR peptide induced AML cell death in cell lines such as U937, K562, THP-1, and HL-60 via activation of caspases 3 and 7, and disruption of mitochondrial membrane potential. Conversely, Antp-TPR peptide did not reduce the viability of normal cells including peripheral blood mononuclear cells (PBMCs), although both geldanamycin and 17-AAG, small-molecule inhibitors of Hsp90, mediated cytotoxicity to these normal cells at low concentrations. In addition, mutation analysis of TPR peptide demonstrated that the highly conserved amino acids Lys and Arg were critical to the cytotoxic activity. These results indicated that Antp-TPR hybrid peptide would provide potent and selective therapeutic options in the treatment of AML.

Identification of DreI as an antiviral factor regulated by RLR signaling pathway

Background

Retinoic acid-inducible gene I (RIG-I)–like receptors (RLRs) had been demonstrated to prime interferon (IFN) response against viral infection via the conserved RLR signaling in fish, and a novel fish-specific gene, the grass carp reovirus (GCRV)-induced gene 2 (Gig2), had been suggested to play important role in host antiviral response.

Methodology/Principal Findings

In this study, we cloned and characterized zebrafish Gig2 homolog (named Danio rerio Gig2-I, DreI), and revealed its antiviral role and expressional regulation signaling pathway. RT-PCR, Western blot and promoter activity assay indicate that DreI can be induced by poly I:C, spring viremia of carp virus (SVCV) and recombinant IFN (rIFN), showing that DreI is a typical ISG. Using the pivotal signaling molecules of RLR pathway, including RIG-I, MDA5 and IRF3 from crucian carp, it is found that DreI expression is regulated by RLR cascade and IRF3 plays an important role in this regulation. Furthermore, promoter mutation assay confirms that the IFN-stimulated regulatory elements (ISRE) in the 5′ flanking region of DreI is essential for its induction. Finally, overexpression of DreI leads to establish a strong antiviral state against SVCV and Rana grylio virus (RGV) infection in EPC (Epithelioma papulosum cyprinid) cells.

Conclusions/Significance

These data indicate that DreI is an antiviral protein, which is regulated by RLR signaling pathway.

[Mechanism of ING4 mediated inhibition of the proliferation and migration of human glioma cell line U251]

AIM

To investigate the effect of Ad-ING4 on proliferation and migration of glioma cells and explore its probable mechanism.

METHODS

U251 were infected with Ad-ING4. ING4 gene expression was evaluated by RT-PCR. MTT assay was adopted to evaluate the effect of ING4 on proliferation of U251; Boyden chamber assay was used to check the effect of ING4 on the migration of U251. In ING4 transfected U251, Western blot was used for detecting NGF and TrkA expression; Pull-down assay was used for detecting active RhoA expression.

RESULTS

ING4 was overexpressed in Ad-ING4 transfected U251 cells. ING4 inhibited proliferation and migration of U251 significantly. Moreover, overexpression of ING4 result in depression of NGF, TrkA and active RhoA.

CONCLUSION

ING4 mediated inhibition of the proliferation and migration of human glioma cells by down regulating NGF, TrkA and active RhoA expression.

[Neurogenin 3 and Paired box gene 4 promote PDX1-induced differentiation of mesenchymal stem cells into pancreatic secretory cells]

OBJECTIVE

To explore the role of neurogenin 3(NGN3) and paired box gene 4(PAX4) in the process of PDX1-driven mesenchymal stem cells (MSCs) to the pancreatic β-cell differentiation.

METHODS

PDX1 gene and NGN3 were constructed with PAX4 genes expression adenovirus vectors, Adxsi-CMV-PDX1 adenovirus infection induced MSCs. One week later, re-Adxsi-CMV-NGN3/CMV-PAX4 adenovirus infection induced MSCs; and detected PDX1, PAX4, NGN3, NK transcription factor related, gene family 2, locus2(NKX2.2), v-maf musculoaponeurotic fibrosarcoma oncogene homolog B(MafB), insulin, glucagon and other pancreatic secretory cell-associated molecule expression.

RESULTS

Adxsi-CMV-PDX1 and Adxsi-CMV-NGN3/CMV-PAX4 adenovirus vectors were constructed successfully. Through immuocytochemistry and indirect fluorescence detection, the expressions of PDX1 and NGN3 and PAX4 factors were detected stably in MSCs cellular nuclei which were induced by Adxsi-CMV-PDX1 and Adxsi-CMV-NGN3/CMV-PAX4. After transfection for 5 d, the cells formed round, gathered into a mass and showed bright red with dithizone staining. RT-PCR detection showed NruroD1 and NKX2.2 expression after being induced for 1 week and insulin/proinsulin molecules after being induced for 2 week. The induced cells could express some transcription factors such as NKX2.2 and MafB, and also pancreatic-secreting related molecules such as insulin and glucagon, but not the expressions of MafA and C-peptide.

CONCLUSION

NGN3 and PAX4 have a favourable role in PDX1 inducing mesenchymal stem cells into pancreatic secretory cells.

[The in vitro and in vivo effects of adenovirus-mediated inhibitor of growth 4 and interleukin-24 co-expression on the radiosensitivity of human lung adenocarcinoma]

OBJECTIVE

To study the radiosensitivity of the recombinant adenoviral vector (called Ad-ING4-IL-24) carrying and co-expressing inhibitor of growth 4 (ING4) and interleukin-24 (IL-24) to human lung adenocarcinoma and the underlying mechanisms.

METHODS

The expression levels of ING4 and IL-24 were detected by Western blot. The growth-suppressing and apoptosis-inducing effect of Ad-ING4-IL-24 combined with radiotherapy on SPC-A-1 lung carcinoma cells were assessed by MTT assay and FCM respectively. The 25 nude mice were randomly divided into 5 groups of 5 mice ecah: PBS group, Ad group, Ad-ING4-IL-24 group, radiotherapy group and joint group (Ad-ING4-IL-24 combined radiotherapy). Mice in all groups except radiotherapy group were intratumorally injected every other day for 6 cycles. The short and long axes of the tumor were measured dynamically, tumor volume was calculated as: V = L × W(2/2), changes in tumor volume were graphed. The human lung carcinoma model was established with SPC-A-1 cells in nude mice. The ratios of tumor-suppression and q were calculated. The expression of Caspase-3, Bcl-2, Bax, VEGF in tumor samples were detected by immunohistochemistry.

RESULTS

The expressions of ING4 and IL-24 were successfully expressed in SPC-A-1 cells. MTT assay and FCM showed that the levels of cell-growth inhibition and apoptosis induction in Ad-ING4-IL-24 combined with radiotherapy group [(86.2 ± 0.8)%, (60.9 ± 1.0)%] were higher than in Ad-ING4-IL-24 group [(49.8 ± 0.3)%, (26.3 ± 1.3)%] and in radiotherapy group [(44.4 ± 2.2)%, (33.3 ± 0.8)%] (ratio of cell-growth inhibition, F = 550.88, P < 0.01; ratio of induced apoptosis F = 614.08, P < 0.01). Ad-ING4-IL-24 combined with radiotherapy showed an enhanced radiosensitivity effect on human lung adenocarcinoma (q = 1.20). In Ad-ING4-IL-24 group, radiotherapy group and Ad-ING4-IL-24 combined with radiotherapy group, the weight inhibition ratio was 49.5% (5 nude mice), 35.4% (5 nude mice), 79.8% (5 nude mice) respectively. Ad-ING4-IL-24 combined with radiotherapy had a synergetic and enhanced radiosensitivity effect on inhibiting the growth of transplanted tumor (q = 1.18). According to immunohistochemistry, Ad-ING4-IL-24 was shown to up-regulate the expression of Bax and Caspase-3 but down-regulate the expression of Bcl-2 and VEGF.

CONCLUSION

Ad-ING4-IL-24 had an enhanced radiosensitivity effect on human lung adenocarcinoma, and therefore acted as a radiotherapy sensitizer, which may be related to its effect on apoptosis-induction and antiangiogenesis.

Prox1 is required for granule cell maturation and intermediate progenitor maintenance during brain neurogenesis

The transcription factor Prox1 plays a crucial role in intermediate progenitor maintenance and hippocampal neuron differentiation during adult neurogenesis in the dentate gyrus region of the hippocampus.

The dentate gyrus has an important role in learning and memory, and adult neurogenesis in the subgranular zone of the dentate gyrus may play a role in the acquisition of new memories. The homeobox gene Prox1 is expressed in the dentate gyrus during embryonic development and adult neurogenesis. Here we show that Prox1 is necessary for the maturation of granule cells in the dentate gyrus during development and for the maintenance of intermediate progenitors during adult neurogenesis. We also demonstrate that Prox1-expressing intermediate progenitors are required for adult neural stem cell self-maintenance in the subgranular zone; thus, we have identified a previously unknown non-cell autonomous regulatory feedback mechanism that controls adult neurogenesis in this region of the mammalian brain. Finally, we show that the ectopic expression of Prox1 induces premature differentiation of neural stem cells.

In the brain, the hippocampus has a crucial role in learning and memory. In mammals, neurogenesis (the birth of new neurons) occurs in the dentate gyrus region of the hippocampus throughout adulthood, and this activity is thought to be the basis for the acquisition of new memories. In this study we describe for the first time the functional roles of the transcription factor Prox1 during brain development and adult neurogenesis. We demonstrate that in mammals, Prox1 is required for the differentiation of granule cells during dentate gyrus development. We also show that conditional inactivation of Prox1 results in the absence of specific intermediate progenitors in the subgranular zone of the dentate gyrus, which prevents adult neurogenesis from occurring. This is the first report showing blockade of adult neurogenesis at the level of progenitor cells. Next, we demonstrate that in the absence of Prox1-expressing intermediate progenitors, the stem cell population of the subgranular zone becomes depleted. Further, we show that Prox1-expressing intermediate progenitors are required for adult neural stem cell self-maintenance in the subgranular zone. Finally, we demonstrate that Prox1 ectopic expression induces premature granule cell differentiation in the subgranular zone. Therefore, our results identify a previously unknown non-cell autonomous feedback mechanism that links adult stem cell self-maintenance with neuronal differentiation in the dentate gyrus and could have important implications for neurogenesis in other brain regions.

Deficiency of the LIM-only protein FHL2 reduces intestinal tumorigenesis in Apc mutant mice

Background

The four and a half LIM-only protein 2 (FHL2) is capable of shuttling between focal adhesion and nucleus where it signals through direct interaction with a number of proteins including β-catenin. Although FHL2 activation has been found in various human cancers, evidence of its functional contribution to carcinogenesis has been lacking.

Methodology/Principal Findings

Here we have investigated the role of FHL2 in intestinal tumorigenesis in which activation of the Wnt pathway by mutations in the adenomatous polyposis coli gene (Apc) or in β-catenin constitutes the primary transforming event. In this murine model, introduction of a biallelic deletion of FHL2 into mutant Apc^Δ14/+ mice substantially reduces the number of intestinal adenomas but not tumor growth, suggesting a role of FHL2 in the initial steps of tumorigenesis. In the lesions, Wnt signalling is not affected by FHL2 deficiency, remaining constitutively active. Nevertheless, loss of FHL2 activity is associated with increased epithelial cell migration in intestinal epithelium, which might allow to eliminate more efficiently deleterious cells and reduce the risk of tumorigenesis. This finding may provide a mechanistic basis for tumor suppression by FHL2 deficiency. In human colorectal carcinoma but not in low-grade dysplasia, we detected up-regulation and enhanced nuclear localization of FHL2, indicating the activation of FHL2 during the development of malignancy.

Conclusions/Significance

Our data demonstrate that FHL2 represents a critical factor in intestinal tumorigenesis.

The PHD fingers of MLL block MLL fusion protein-mediated transformation

Chromosomal translocations involving the mixed lineage leukemia (MLL) gene are associated with aggressive acute lymphoid and myeloid leukemias. These translocations are restricted to an 8.3-kb breakpoint region resulting in fusion of amino terminal MLL sequences in frame to 1 of more than 60 different translocation partners. The translocations consistently delete the plant homeodomain (PHD) fingers and more carboxyl terminal MLL sequences. The function of the PHD fingers is obscure and their specific role in transformation has not been explored. Here we show that inclusion of the PHD fingers in the MLL fusion protein MLL-AF9 blocked immortalization of hematopoietic progenitors. Inclusion of 2 or more PHD fingers reduced association with the Hoxa9 locus and suppressed Hoxa9 up-regulation in hematopoietic progenitors. These data provide an explanation for why MLL translocation breakpoints exclude the PHD fingers and suggest a possible role for these domains in regulating the function of wild-type MLL.

Defining the transcriptional regulation of the intestinal sodium-glucose cotransporter using RNA-interference mediated gene silencing

BACKGROUND

The sodium glucose cotransporter (SGLT1) is responsible for all active intestinal glucose uptake. Hepatocyte nuclear factors 1 alpha and beta (HNF 1 alpha and HNF 1 beta) activate the SGLT1 promoter, whereas GATA-binding protein 5 (GATA-5) and caudal-type homeobox protein 2 (CDX2) regulate transcription of other intestinal genes. We investigated SGLT1 regulation by these transcription factors using promoter studies and RNA interference.

METHODS

Chinese hamster ovary (CHO) cells were transiently cotransfected with an SGLT1-luciferase promoter construct and combinations of expression vectors for HNF 1 alpha, HNF 1 beta, CDX2, and GATA-5. Caco-2 cells were stably transfected with knockdown vectors for either HNF 1 alpha or HNF 1 beta. mRNA levels of HNF 1 alpha, HNF 1 beta, and SGLT1 were determined using quantitative polymerase chain reaction (qPCR).

RESULTS

HNF 1 alpha, GATA-5, and HNF 1 beta significantly activated the SGLT1 promoter (P < .05). Cotransfection of GATA-5 with HNF 1 alpha had an additive effect, whereas HNF 1 beta and CDX2 antagonized HNF 1 alpha and GATA-5. SGLT1 expression was significantly reduced in HNF 1 alpha or HNF 1 beta knockdowns (P < .001). HNF alpha knockdown significantly reduced HNF 1 beta expression and vice versa (P < .005).

CONCLUSIONS

HNF 1 alpha and HNF 1 beta are important transcription factors for endogenous SGLT1 expression by cultured enterocytes. GATA-5 and CDX2 also regulate SGLT1 promoter activity and show cooperativity with the HNF1s. We, therefore, propose a multifactorial model for SGLT1 regulation, with interactions between HNF1, GATA-5, and CDX2 modulating intestinal glucose absorption.

Pax4 paired domain mediates direct protein transduction into mammalian cells

Pax4, a paired-box transcription factor, is a key regulator of pancreatic islet cell growth and differentiation. Here, we report for the first time that the Pax4 protein can permeate into various cell types including pancreatic islets. The paired domain of Pax4 serves as a novel protein transduction domain (PTD). The Pax4 protein can transduce in a dose- and time-dependent manner. The cellular uptake of Pax4 PTD can be completely blocked by heparin, whereas cytochalasin D and amiloride were partially effective in blocking the Pax4 protein entry. Transduced intact Pax4 protein functions similarly to the endogenous Pax4. It inhibits the Pax6 mediated transactivation and protects Min6 cells against TNFalpha-induced apoptosis. These data suggest that Pax4 protein transduction could be a safe and valuable strategy for protecting islet cell growth in culture from apoptosis and promoting islet cell differentiation.

The HOXB4 homeoprotein differentially promotes ex vivo expansion of early human lymphoid progenitors

The HOXB4 homeoprotein is known to promote the expansion of mouse and human hematopoietic stem cells (HSCs) and progenitors of the myeloid lineages. However, the putative involvement of HOXB4 in lymphopoiesis and particularly in the expansion of early lymphoid progenitor cells has remained elusive. Based on the ability of the HOXB4 protein to passively enter hematopoietic cells, our group previously designed a long-term culture procedure of human HSCs that allows ex vivo expansion of these cells. Here, this method has been further used to investigate whether HOXB4 could cause similar expansion on cells originating from CD34(+) hematopoietic progenitor cells (HPCs) committed at various levels toward the lymphoid lineages. We provide evidence that HOXB4 protein delivery promotes the expansion of primitive HPCs that generate lymphoid progenitors. Moreover, HOXB4 acts on lymphomyeloid HPCs and committed T/natural killer HPCs but not on primary B-cell progenitors. Our results clarify the effect of HOXB4 in the early stages of human lymphopoiesis, emphasizing the contribution of this homeoprotein in the maintenance of the intrinsic lymphomyeloid differentiation potential of defined HPC subsets. Finally, this study supports the potential use of HOXB4 protein for HSC and HPC expansion in a therapeutic setting and furthers our understanding of the mechanisms of the molecular regulation of hematopoiesis.

Purification of the Prep1 interactome identifies novel pathways regulated by Prep1

Prep1 homeodomain transcription factor interacts with Pbx proteins to regulate oculogenesis, angiogenesis, and hematopoiesis in mice. To isolate new Prep1 interactors competing or copurifying with Pbx, we identified proteins copurified with Prep1-TAP by tandem affinity purification (TAP). Prep1-TAP was fully functional and allowed the isolation of a Prep1 proteome from cytoplasm and nucleus, but most interactors were nuclear. The Prep1-TAP complex included Pbx1b, Pbx2, and other nonhomeodomain proteins: p160 Myb-binding protein (p160), beta-actin, NMMHCIIA.

Transcription factors GATA-1 and Fli-1 regulate human HOXA10 expression in megakaryocytic cells

HOXA10 is a member of the HOX family of regulatory genes that are involved in hematopoiesis. Its role in megakaryopoiesis has been suggested by its expression in immature megakaryocytes and by the proliferation of megakaryocyte-primitive blast colonies upon HOXA10 overexpression. We sought to understand the role of HOXA10 in megakaryopoiesis better, by investigating its transcriptional regulation. Analysis of the 5' untranslated region and transfection of promoter/plasmids into human tissue culture cell lines identified transcriptionally active sequences that contain GATA-1 and Ets-1 sites and a putative binding site for its neighboring gene, HOXA11. Gel shift assays confirmed protein-DNA interactions at these sites. Mutation of the GATA-1 and the Ets-1 motifs amplified the expression of HOXA10 in HEL and K562 cells, confirming the importance of these cis-acting elements in regulating HOXA10 expression in megakaryocytic cells. Chromatin immunoprecipitation (ChIP) and chloramphenicol acetyl transferase (CAT) assays confirm that HOXA11 binds to the putative binding site, resulting in repression of HOXA10 expression. These data taken together give insight into the regulation of HOXA10 expression in megakaryocytic differentiation.

The peptide NAP promotes neuronal growth and differentiation through extracellular signal-regulated protein kinase and Akt pathways, and protects neurons co-cultured with astrocytes damaged by ethanol

We have previously shown that glial cells are a target of ethanol toxicity during brain ontogeny, since ethanol affects glial development and impairs the release of neurotrophic factors which are important for neuronal outgrowth and synaptic plasticity. Activity-dependent neuroprotective protein (ADNP) is a glial factor with anti-apoptotic and neuroprotective actions. We proposed that some ethanol effects on brain development and synaptic formation are, in part, mediated by the ethanol-induced impairment of the synthesis and release of ADNP by astroglial cells. We show a reduction in the ADNP mRNA levels in the cerebral cortex and astrocytes from prenatal ethanol exposed (PEE) foetuses. Furthermore, co-cultures of PEE astrocytes with control neurons cause a marked decrease in neuronal growth, differentiation and synaptic connections relative to the co-cultures with control astrocytes, effects that were reverted by the addition of NAP, the active peptide of ADNP. We further show that one mechanism by which NAP could exert its actions is the activation of mitogen-activated protein kinase/extracellular signal-regulated protein kinase, the phosphatidylinositol-3-kinase (PI-3K)/Akt pathways and the transcription factor cAMP response element-binding protein. These results indicate that the protective actions of NAP are mediated by triggering signalling pathways which are important in neuronal growth and differentiation contributing to the restoration of PEE-associated neuronal plasticity.

Forced expression of Nanog in hematopoietic stem cells results in a gammadeltaT-cell disorder

Nanog is a key molecule involved in the maintenance of the self-renewal of undifferentiated embryonic stem (ES) cells. In this work we investigate whether Nanog can enhance self-renewal in hematopoietic stem cells. Contrary to our expectation, no positive effect of Nanog transduction was detected in bone marrow reconstitution assays. However, recipients of Nanog-transduced (Nanog) hematopoietic stem cells (HSCs) invariantly develop a unique disorder typified by an atrophic thymus occupied by Nanog-expressing gammadeltaT-cell receptor-positive (TCR(+)) cells (Nanog T cells). All thymi are eventually occupied by Nanog T cells with CD25(+)CD44(+) surface phenotype that home selectively to the thymus on transfer and suppress normal thymocyte development, which is partly ascribed to destruction of the microenvironment in the thymus cortex. Moreover, this initial disorder invariantly develops to a lymphoproliferative disorder, in which Nanog T cells undergo unlimited proliferation in the peripheral lymphoid tissues and eventually kill the host. This invariable end result suggests that Nanog is a candidate oncogene for gammadeltaT-cell malignancy.

Recombinant activity-dependent neuroprotective protein protects cells against oxidative stress

Activity-dependent neuroprotective protein (ADNP) is essential for brain formation. Here, we investigated the potential neuroprotective effects of recombinant ADNP under stress conditions. The human ADNP cDNA was sub-cloned into a vector that contains VP22, a Herpes virus protein that may allow penetration of fused proteins through cellular membranes. When incubated with pheochromocytoma (PC12) cells, a neuronal model, VP22-ADNP was associated with the cells after a 25-min incubation period. Pre-incubation with VP22-ADNP enriched protein fractions protected against beta amyloid peptide toxicity and oxidative stress (H2O2) in PC12 cells. VP22 by itself was devoid of protective activity. Furthermore, the pro-apoptotic protein p53 increased by 3.5-fold from control levels in the presence of H2O2, while treatment with VP22-ADNP prior to H2O2 exposure significantly reduced the p53 protein levels. ADNP expression was previously shown to oscillate as a function of the estrus cycle in the mouse arcuate nucleus, these oscillations are now correlated with increased cellular protection.

HES1 cooperates with pRb to activate RUNX2-dependent transcription

The retinoblastoma protein, pRb, can activate the transcription factor RUNX2, an essential regulator of osteogenic differentiation, but the mechanism of this activation is unknown. Here we studied the interaction of pRb and RUNX2 with HES1, previously reported to augment RUNX2 activity. PRb can act to promote RUNX2/HES1 association with concomitant promoter occupancy and transcriptional activation in bone cells.

INTRODUCTION

RUNX2 (also known as OSF2/CBFA1) is a transcription factor required for osteoblast differentiation and bone formation. We have reported that RUNX2 can associate with the retinoblastoma protein pRb, a common tumor suppressor in bone, and the resultant complex can bind and activate transcription from bone-specific promoters. This activity of the pRb/RUNX2 complex may thus link differentiation control with tumor suppressor activity. However, the mechanism through which pRb can activate RUNX2 is unknown. HES1 is a reported co-activator of RUNX2 that shares a binding site on RUNX2 with pRb. Thus, we have tested the cooperativity among these factors in activating transcription from bone specific promoters.

MATERIALS AND METHODS

Coimmunoprecipitation, chromatin immunoprecipitation, and EMSA experiments were used to study the interaction of RUNX2, HES1, and pRb in cell lysates and on DNA. Transcriptional reporter assays were used to analyze the activity of RUNX2 in the presence and absence of HES1 and pRb.

RESULTS

We showed that pRb can associate with HES1, a previously described RUNX2 interactor that can itself augment RUNX2-dependent transcription. The association of HES1 with RUNX2 is augmented by pRb. Furthermore, both pRb and HES1 increase the amount of RUNX2 bound to promoter sites in vivo, pRb and HES1 synergistically activate a RUNX2-dependent reporter gene, and depletion of HES1 reduces RUNX2/pRb activity.

CONCLUSIONS

These data indicate that pRb acts as a RUNX2 co-activator at least in part by recruiting HES1 into the pRb/RUNX2 complex and further elucidate a novel role for pRb as a transcriptional co-activator in osteogenesis.

Quantitative production of macrophages or neutrophils ex vivo using conditional Hoxb8

Differentiation mechanisms and inflammatory functions of neutrophils and macrophages are usually studied by genetic and biochemical approaches that require costly breeding and time-consuming purification to obtain phagocytes for functional analysis. Because Hox oncoproteins enforce self-renewal of factor-dependent myeloid progenitors, we queried whether estrogen-regulated Hoxb8 (ER-Hoxb8) could immortalize macrophage or neutrophil progenitors that would execute normal differentiation and normal innate immune function upon ER-Hoxb8 inactivation. Here we describe methods to derive unlimited quantities of mouse macrophages or neutrophils by immortalizing their respective progenitors with ER-Hoxb8 using different cytokines to target expansion of different committed progenitors. ER-Hoxb8 neutrophils and macrophages are functionally superior to those produced by many other ex vivo differentiation models, have strong inflammatory responses and can be derived easily from embryonic day 13 (e13) fetal liver of mice exhibiting embryonic-lethal phenotypes. Using knockout or small interfering RNA (siRNA) technologies, this ER-Hoxb8 phagocyte maturation system represents a rapid analytical tool for studying macrophage and neutrophil biology.

PDX-1 can repress stimulus-induced activation of the INGAP promoter

Islet neogenesis associated protein (INGAP) promotes the generation of new islet mass in adult animal models. It is not understood what factors control the expression of INGAP. In this study, factors that regulate the expression of INGAP promoter activity are reported. To determine factors that regulate INGAP expression, we previously cloned the promoter region for INGAP. Analysis of the INGAP promoter suggested that candidate regulators of INGAP expression include the transcription factors PDX-1, NeuroD, PAN-1, STAT and AP-1. Using gene addition experiments in the 293 cell line the activity of these transcription factors on an INGAP-promoter construct linked to the beta-galactosidase reporter has been determined. Induction of AP-1 activity or STAT activity using PMA or LIF stimulation respectively, or direct expression of PAN-1 specifically up-regulates INGAP promoter activity. In contrast, co-expression of PDX-1 but not NeuroD inhibits activation of the INGAP-promoter driven by PAN-1, PMA or LIF stimulation. PDX-1 binds directly to the INGAP promoter as determined in electromobility shift and antibody supershift assays. Expression of the INGAP-promoter-reporter construct in the HIT-T15 beta-cell line, a cell line that expresses endogenous PDX-1, did not reveal PMA-mediated stimulation of INGAP promoter activity. HIT-T15 cells however did efficiently transfect (> 68%) and respond (2-fold) to PMA-induced signal transduction to a transfected AP-1-CAT reporter. Partial reduction of PDX-1 expression in HIT-T15 cells was associated with recovery of PMA induced INGAP promoter activity. These data suggest that expression of PDX-1 is associated with a repression of stimulus-induced INGAP promoter activity that appears to be mediated by a direct DNA interaction. These findings implicate PDX-1 in a possible feedback loop to block unbridled islet expansion.

[Gene regulatory mechanism of hairy and enhancer of split related-1 for angiogenesis factors]

OBJECTIVE

To study the roles of hairy and enhancer of split related-1 (HESR-1) in maintenance of the mature, quiescent vessel and angiogenesis.

METHODS

Human umbilical vein endothelial cells (HUVEC) were cultured. The full-length coding sequence of HESR-1 was cloned into PcDNA3.1 + using standard protocols. HESR-1 specific siRNA was synthesized and cloned into the RNAi-Ready pSIREN-RetroQ ZsGreen Vector. The constructed PcDNA3.1 + HESR-1 plasmid were transfected into HUVEC for the overexpression of HESR-1, and HESR-1-RNAi plasmid were transfected into HUVEC to silence the HESR-1 gene, the expression of KDR, ALK-1 and Ang-1 in HUVEC were analyzed by RT-PCR and Western blot.

RESULTS

The expression of KDR was down-regulated and ALK-1 and Ang-1 were up-regulated in HUVEC with the overexpression of HESR-1; The expression of KDR was up-regulated and ALK-1 and Ang-1 were down-regulated the HESR-1 in HUVEC by RNAi.

CONCLUSION

HESR-1 may play an important role in maintenance of vessel in quiescent and control angiogenesis by the regulation of the expression of KDR, ALK-1 and Ang-1.

HOXB4 overexpression promotes hematopoietic development by human embryonic stem cells

Human embryonic stem cells (hESCs) are a potential source of hematopoietic cells for therapeutic transplantation and can provide a model for human hematopoiesis. Culture of hESCs on murine stromal layers or in stromal-free conditions as embryoid bodies results in low levels of hematopoietic cells. Here we demonstrate that overexpression of the transcription factor HOXB4 considerably augments hematopoietic development of hESCs. Stable HOXB4-expressing hESC clones were generated by lipofection and could be maintained in the undifferentiated state for prolonged passages. Moreover, differentiation of hESCs as embryoid bodies in serum-containing medium without the use of additional cytokines led to sequential expansion of first erythroid and then myeloid and monocytic progenitors from day 10 of culture. These cells retained the capacity to develop into formed blood elements during in vitro culture. Consistent with the development of committed hematopoietic cells, we observed the expression of transcription factors known to be critical for hematopoietic development. We thus demonstrate successful use of enforced gene expression to promote the differentiation of hESCs into a terminally differentiated tissue, thereby revealing an important role for HOXB4 in supporting their in vitro development along the hematopoietic pathway.

Expansion ex vivo des cellules souches hématopoïétiques humaines par la transduction passive de l'homéoprotéine HOXB4

Expansion of human hematopoietic stem cells (HSCs) is a challenge for cellular therapy. It currently relies on either the use of recombinant cytokines or transfer of transcription factor genes. Among these, the HOXB4 homeoprotein is of particular interest since it promotes the expansion of mouse HSCs without inducing leukemia. To prevent potential deleterious side effects associated with stable HOXB4 gene transfer into the cells, we took advantage of the ability of homeoproteins to passively pass through cell membranes. We have shown that, when co-cultured with stromal cells engineered to secrete HOXB4, human stem cells and immature progenitors clearly were expanded. This expansion was associated with enhanced stem cell repopulating capacity in vivo and maintenance of pluripotentiality. The role that HOXB4 plays on stem cell expansion has also been tested on human lymphoid progenitors. We found that our model of protein transfer was also able to induce the expansion of the immature lympho-myeloid and pro-T/NK progenitors as well as of more mature NK progenitors. We then looked for synergistic activities between HOXB4 and other homeoproteins such as HOXC4. We found that HOXC4 was able to promote the expansion of human hematopoietic cells in vitro roughly as HOXB4 did and that the presence of both HOXB4 and HOXC4 molecules induced even higher expansion levels of these cells. Our method provides a basis for developing cell therapy strategies using expanded HSCs that are not genetically modified.

The transcription factor Engrailed-2 guides retinal axons

Engrailed-2 (En-2), a homeodomain transcription factor, is expressed in a caudal-to-rostral gradient in the developing midbrain, where it has an instructive role in patterning the optic tectum--the target of topographic retinal input. In addition to its well-known role in regulating gene expression through its DNA-binding domain, En-2 may also have a role in cell-cell communication, as suggested by the presence of other domains involved in nuclear export, secretion and internalization. Consistent with this possibility, here we report that an external gradient of En-2 protein strongly repels growth cones of Xenopus axons originating from the temporal retina and, conversely, attracts nasal axons. Fluorescently tagged En-2 accumulates inside growth cones within minutes of exposure, and a mutant form of the protein that cannot enter cells fails to elicit axon turning. Once internalized, En-2 stimulates the rapid phosphorylation of proteins involved in translation initiation and triggers the local synthesis of new proteins. Furthermore, the turning responses of both nasal and temporal growth cones in the presence of En-2 are blocked by inhibitors of protein synthesis. The differential guidance of nasal and temporal axons reported here suggests that En-2 may participate directly in topographic map formation in the vertebrate visual system.

Agonistic and antagonistic action of AP2, Msx2, Pax6, Prox1 AND Six3 in the regulation of Sox2 expression

Sox2 transcription factor is expressed in neural tissues and sensory epithelia from the early stages of development. Particularly, it is known to activate crystallin gene expression and to be involved in differentiation of lens and neural tissues. However, its place in the signaling cascade is not well understood. Here, we report about the response of its promoter to the presence of other transcription factors, AP2alpha, Msx2, Pax6, Prox1 and Six3, in a transient reporter gene assay using HEK293 cells as recipient cells. Taking our data together, AP2, Pax6 and PROX1 can activate the Sox2 promoter. Msx2 has an inhibitory effect, whereas Six3 does not affect the Sox2 promoter. These data indicate a common activating cascade at least for AP2, Pax6, Prox1 and Sox2.

A genetic screen identifies PITX1 as a suppressor of RAS activity and tumorigenicity

Activating mutations of RAS frequently occur in subsets of human cancers, indicating that RAS activation is important for tumorigenesis. However, a large proportion of these cancers still retain wild-type RAS alleles, suggesting that either the RAS pathway is activated in a distinct manner or another pathway is deregulated. To uncover novel tumor-suppressor genes, we screened an RNA-interference library for knockdown constructs that transform human primary cells in the absence of ectopically introduced oncogenic RAS. Here we report the identification of PITX1, whose inhibition induces the RAS pathway and tumorigenicity. Interestingly, we observed low expression of PITX1 in prostate and bladder tumors and in colon cancer cell lines containing wild-type RAS. Restoration of PITX1 in the colon cancer cells inhibited tumorigenicity in a wild-type RAS-dependent manner. Finally, we identified RASAL1, a RAS-GTPase-activating protein, as a transcription target through which PITX1 affects RAS function. Thus, PITX1 suppresses tumorigenicity by downregulating the RAS pathway through RASAL1.

L3/Lhx8 is involved in the determination of cholinergic or GABAergic cell fate

The LIM homeobox family of transcription factors is involved in many processes during the development of the mammalian central nerves system. L3, also called Lhx8 (L3/Lhx8), is a recently identified member of the LIM homeobox gene family and is selectively expressed in the medial ganglionic eminence (MGE). Our previous study demonstrated that L3/Lhx8-null mice specifically lacked cholinergic neurons in the basal forebrain. In this study, we reduced L3/Lhx8 function in the murine neuroblastoma cell line, Neuro2a (N2a), using L3/Lhx8-targeted small interfering RNA (siRNA) produced by H1.2 promoter-driven vector. The levels of cholinergic markers per cell were diminished without a reduction in the number of marker-positive cells. Intriguingly, GABAergic marker expression and the number of GABAergic cells were dramatically increased in the differentiating L3/Lhx8-knockdown N2a. These results suggest the possibility that L3/Lhx8 is involved in the determination of transmitter phenotypes (GABAergic or cholinergic cell fate) in a population of neurons during basal forebrain development.

Polyamines are necessary for synthesis and stability of occludin protein in intestinal epithelial cells

Occludin is an integral membrane protein that forms the sealing element of tight junctions and is critical for epithelial barrier function. Polyamines are implicated in multiple signaling pathways driving different biological functions of intestinal epithelial cells (IEC). The present study determined whether polyamines are involved in expression of occludin and play a role in intestinal epithelial barrier function. Studies were conducted in stable Cdx2-transfected IEC-6 cells (IEC-Cdx2L1) associated with a highly differentiated phenotype. Polyamine depletion by alpha-difluoromethylornithine (DFMO) decreased levels of occludin protein but failed to affect expression of its mRNA. Other tight junction proteins, zonula occludens (ZO)-1, ZO-2, claudin-2, and claudin-3, were also decreased in polyamine-deficient cells. Decreased levels of tight junction proteins in DFMO-treated cells were associated with dysfunction of the epithelial barrier, which was overcome by exogenous polyamine spermidine. Decreased levels of occludin in polyamine-deficient cells was not due to the reduction of intracellular-free Ca(2+) concentration ([Ca(2+)](cyt)), because either increased or decreased [Ca(2+)](cyt) did not alter levels of occludin in the presence or absence of polyamines. The level of newly synthesized occludin protein was decreased by approximately 70% following polyamine depletion, whereas its protein half-life was reduced from approximately 120 min in control cells to approximately 75 min in polyamine-deficient cells. These findings indicate that polyamines are necessary for the synthesis and stability of occludin protein and that polyamine depletion disrupts the epithelial barrier function, at least partially, by decreasing occludin.

Highly efficient, nonpeptidic oligoguanidinium vectors that selectively internalize into mitochondria

Oligoguanidinium-based cell delivery systems have gained broad interest in the drug delivery field since one decade ago. Thus, arginine-containing peptides as Tat or Antp, oligoarginine peptides, and derived peptoids have been described as shuttles for delivering nonpermeant drugs inside cancer cells. Herein we report a new family of tetraguanidinium cell penetrating vectors efficiently internalized in human tumor cells. Their high internalization, studied by confocal microscopy and flow cytometry, as well as their specific accumulation in mitochondria makes these new vectors likely vehicles for the targeted delivery of anticancer drugs to mitochondria.

The role of notch signaling in the development of intrahepatic bile ducts

BACKGROUND & AIMS

Mutations in Jagged1 , a Notch ligand, cause Alagille syndrome (AGS), a disorder characterized by a paucity of intrahepatic bile ducts (IHBD). The mechanism underlying the contribution of the Notch signaling pathway to IHBD formation, however, remains unknown. Here we investigated the role of Notch signaling in IHBD development.

METHODS

The expression patterns of Jagged1, Notch2, and Hes1 during mouse liver development were analyzed by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR), immunoblot, and immunohistochemistry. The hepatocyte maturation level and IHBD development were studied in Hes1 null mice in comparison with wild-type mice. The effect of Jagged1 on biliary differentiation was assessed by using an in vitro 2-cell coculture system with WB-F344 cells, a cell line derived from normal adult rat liver.

RESULTS

Jagged1 was expressed in the portal mesenchyme during the neonatal period. During the same period, Notch2 and Hes1 expression was observed in the biliary epithelial cells adjacent to the Jagged1-positive cells. During ductal plate remodeling, Notch2 and Hes1 were up-regulated exclusively in the biliary epithelial cells that form tubular structures. In contrast, the tubular formation of IHBD was completely absent in Hes1 null mice. Coculture with Balb3T3 cells stably overexpressing Jagged1 induced transactivation of the Hes1 promoter and increased expression of biliary lineage markers, such as cytokeratin-19 and gamma-glutamyl transpeptidase, in WB-F344 cells.

CONCLUSIONS

Our results suggest that Notch signaling has an important role in the differentiation of biliary epithelial cells and is essential for their tubular formation during IHBD development.

In vitro and in vivo expansion of hematopoietic stem cells

The capacity for sustained self-renewal--the generation of daughter cells having the same regenerative properties as the parent cell--is the defining feature of hematopoietic stem cells (HSCs). Strong evidence exists that self-renewal of HSC is under extrinsic biological control in vivo. A variety of cytokines, morphogenic ligands and associated signaling components influence self-renewal in culture and in vivo. Specific homeobox transcription factors act as powerful intrinsic agonists of HSC self-renewal in vitro and in vivo when supplied either as transduced cDNAs or as externally delivered proteins. These findings provide tools for deepening our knowledge of mechanism and for achievement of clinically useful levels of HSC expansion.

Pbx1 is essential for adrenal development and urogenital differentiation

Pbx1 encodes a TALE (three amino acid loop extension) class homeodomain protein that participates in multimeric transcriptional complexes to regulate developmental gene expression. Previous studies demonstrate a critical role for Pbx1 as a developmental regulator whose absence results in embryonic lethality and multiple tissue and organ system abnormalities. Here we report a requirement for Pbx1 in the differentiation of urogenital organs, where Pbx1 is widely expressed in mesenchymal tissues. The complete lack of adrenal glands and formation of gonads displaying rudimentary sexual differentiation correlated with decreased cellular proliferation in Pbx1(-/-) genital ridges. Furthermore, expression of steroidogenic factor-1 (SF-1), a nuclear receptor essential for adrenal organogenesis, was reduced to minimal levels in Pbx1 mutants, indicating an upstream function for Pbx1 in adrenocortical development. Finally, loss of Pbx1 markedly reduces urogenital ridge outgrowth and results in impaired differentiation of the mesonephros and kidneys and the absence of Müllerian ducts. These findings establish a Pbx1-dependent pathway that regulates the expansion of SF-1 positive cells essential for adrenal formation and gonadal differentiation and demonstrate an early requirement for Pbx1 in urogenital development.

Snail and SIP1 increase cancer invasion by upregulating MMP family in hepatocellular carcinoma cells

Loss of E-cadherin (E-cad) triggers invasion, metastasis, and dedifferentiation in various epithelial carcinomas. Recently, it has been reported that two transcription factors, Snail and SIP1 (Smad interacting protein 1), directly repress transcription of the E-cad gene by binding E-box on E-cad promoter. Our aim is to solve the molecular mechanism of Snail and SIP1 in hepatocellular carcinoma (HCC). We first showed an inverse correlation between E-cad and Snail/SIP 1 expression among five HCC lines with different phenotypes. The result indicated that undifferentiated, but not differentiated type expressed Snail/SIP1. Then, we established transfectants stably expressing Snail and SIP1 in two differentiated cells with E-cad expression. Suppressed expression of E-cad, morphologic change into fibroblastoid feature, and remarkable acceleration of invasion activity were observed in the transfectants. In reverse transcription–polymerase chain reaction series of genes relating to motility and invasion, we demonstrated striking evidence that matrix metalloproteinase (MMP-1), MMP-2, MMP-7, and MT1-MMP expressions were strongly upregulated by Snail. On the other hand, MMP-1, MMP-2, and MT1-MMP expressions were enhanced by SIP1 transfection, however, the intensity was weaker than that in Snail transfection. In conclusion, Snail or SIP1 expression may be induced during HCC progression, where Snail/SIP1 directly represses E-cad gene transcription and activates cancer invasion via the upregulation of the MMP gene family.

[Extreme divergence of a homeotic gene: the bicoid case]

Evolutionary developmental genetics (evo-devo) reveals that the plasticity of development is so important that every developmental biology project should carefully take this point into consideration. The example of bicoid, the first discovered morphogen, illustrates how an essential gene can change its function during evolution. The search for bicoid homologues showed that this gene is surprisingly specific to flies (cyclorraphan diptera) and absent in other insects. In fact, recent studies demonstrate that bicoid is a very derived Hox3 homeotic gene. During insect evolution, the ancestral Hox3 gene lost its homeotic function and acquired new roles in oocytes and embryonic annexes. Then, in the lineage leading to modern flies, a duplication of this new gene, followed by functional divergence, led to the formation of bicoid and zerknüllt. Both genes are located within the Drosophila Hox complex; however, they have no homeotic function. Thanks to the power of Drosophila genetics, it is possible to suggest that torso and hunchback may constitute the insect primitive anterior organizer. The bicoid evolutionary history reveals several fundamental mechanisms of the evolution of developmental genes, such as changes of gene regulation, modifications of protein sequences and gene duplication. It also shows the need for studying a wider range of model organisms before generalisations can be made from data obtained with one particular species.

HoxD3 accelerates wound healing in diabetic mice

Poorly healing diabetic wounds are characterized by diminished collagen production and impaired angiogenesis. HoxD3, a homeobox transcription factor that promotes angiogenesis and collagen synthesis, is up-regulated during normal wound repair whereas its expression is diminished in poorly healing wounds of the genetically diabetic (db/db) mouse. To determine whether restoring expression of HoxD3 would accelerate diabetic wound healing, we devised a novel method of gene transfer, which incorporates HoxD3 plasmid DNA into a methylcellulose film that is placed on wounds created on db/db mice. The HoxD3 transgene was expressed in endothelial cells, fibroblasts, and keratinocytes of the wounds for up to 10 days. More importantly, a single application of HoxD3 to db/db mice resulted in a statistically significant acceleration of wound closure compared to control-treated wounds. Furthermore, we also observed that the HoxD3-mediated improvement in diabetic wound repair was accompanied by increases in mRNA expression of the HoxD3 target genes, Col1A1 and beta 3-integrin leading to enhanced angiogenesis and collagen deposition in the wounds. Although HoxD3-treated wounds also show improved re-epithelialization as compared to control db/db wounds, this effect was not due to direct stimulation of keratinocyte migration by HoxD3. Finally, we show that despite the dramatic increase in collagen synthesis and deposition in HoxD3-treated wounds, these wounds showed normal remodeling and we found no evidence of abnormal wound healing. These results indicate that HoxD3 may provide a means to directly improve collagen deposition, angiogenesis and closure in poorly healing diabetic wounds.