Quantification of cellular uptake and in vivo tracking of transduction using real-time monitoring.

Biochem Biophys Res Commun. 2010 Mar 3;

Authors: Lee MS, Kwon EH, Choi HS, Kwon SH, Shim IS, Lee SK, Her S

Protein transduction domains (PTDs) are short amino acid sequences that promote their own translocation across the cell plasma membrane and have been studied for possible use in drug delivery and gene therapy. However, no direct method to quantify transduction is available. Here, using a new luciferase-tagged human PTD, we show that cellular uptake levels can be determined in a reliable manner. Furthermore, we show that enhanced in vivo tracking by human PTD can be quantified in a mouse model. This is the first report on the direct quantification of PTD transduction in vitro and in vivo, which will be necessary for studying its possible therapeutic application in drug delivery and gene therapy.

PMID: 20206600 [PubMed - as supplied by publisher]

miR-29 is a key regulator of collagen expression in systemic sclerosis.

Arthritis Rheum. 2010 Mar 3;

Authors: Maurer B, Stanczyk J, Jüngel A, Akhmetshina A, Trenkmann M, Brock M, Kowal-Bielecka O, Gay RE, Michel BA, Distler JH, Gay S, Distler O

OBJECTIVE: To investigate the role of microRNAs as posttranscriptional regulators of profibrotic genes in systemic sclerosis (SSc). METHODS: MicroRNAs which target collagens were identified by in silico analysis. Expression of miR-29 was determined by TaqMan Real-time PCR in skin biopsies and fibroblasts from SSc patients and healthy controls and in the mouse model of bleomycin-induced skin fibrosis. Cells were transfected with pre/anti-miRs of miR-29 using lipofectamine. Collagen gene expression was also studied in Luciferase reporter gene assays. For stimulation recombinant TGF-beta, PDGF-B or IL-4 were used. The effects of inhibiting PDGF-B and TGF-beta signalling on the levels of miR-29 were studied in vitro and in the bleomycin model. RESULTS: miR-29a was strongly downregulated in SSc fibroblasts and skin sections compared to healthy controls. Overexpression in SSc fibroblasts significantly decreased, and accordingly, knockdown in normal fibroblasts increased collagen types I and III mRNA and protein. In the reporter gene assay, co-transfection with pre-miR-29a significantly decreased the relative luciferase activity suggesting a direct regulation of collagen by miR-29a. TGF-beta, PDGF-B or IL-4 reduced the levels miR-29a in normal fibroblasts to a level as seen in SSc fibroblasts. Similar to human SSc, the expression of miR-29a was reduced in the bleomycin model. Inhibition of PDGF-B and TGF-beta pathways by treatment with imatinib restored the levels of miR-29a in vitro and in the bleomycin model in vivo. CONCLUSION: These data add the posttranscriptional regulation of collagens by miR-29a as a novel aspect to the fibrogenesis of SSc and suggest miR-29a as a potential therapeutic target.

PMID: 20201077 [PubMed - as supplied by publisher]

Akt is a direct target for myricetin to inhibit cell transformation.

Mol Cell Biochem. 2009 Dec;332(1-2):33-41

Authors: Kumamoto T, Fujii M, Hou DX

Akt, a serine/threonine kinase, is a critical regulator in many cellular processes including cell growth, proliferation, and apoptosis. In this study, we found that myricetin, a typical flavonol existing in many fruits and vegetables, could directly target Akt to inhibit cell transformation. Binding assay revealed that myricetin bound to Akt directly by competing with ATP. In vitro and ex vivo data confirmed that myricetin inhibited the phosphorylation and kinase activity of Akt. Molecular modeling suggested that myricetin easily docks to the ATP-binding site of Akt with hydrogen bonds. Signaling analysis data further demonstrated that myricetin inhibited Akt-mediated activator protein-1 (AP-1) transactivation, cyclin D1 expression and cell transformation. Overall, our results indicate that Akt is a direct target for myricetin to inhibit cell transformation.

PMID: 19504174 [PubMed - indexed for MEDLINE]

Oncostatin M promotes bone formation independently of resorption when signaling through leukemia inhibitory factor receptor in mice.

J Clin Invest. 2010 Feb 1;120(2):582-92

Authors: Walker EC, McGregor NE, Poulton IJ, Solano M, Pompolo S, Fernandes TJ, Constable MJ, Nicholson GC, Zhang JG, Nicola NA, Gillespie MT, Martin TJ, Sims NA

Effective osteoporosis therapy requires agents that increase the amount and/or quality of bone. Any modification of osteoclast-mediated bone resorption by disease or drug treatment, however, elicits a parallel change in osteoblast-mediated bone formation because the processes are tightly coupled. Anabolic approaches now focus on uncoupling osteoblast action from osteoclast formation, for example, by inhibiting sclerostin, an inhibitor of bone formation that does not influence osteoclast differentiation. Here, we report that oncostatin M (OSM) is produced by osteoblasts and osteocytes in mouse bone and that it has distinct effects when acting through 2 different receptors, OSM receptor (OSMR) and leukemia inhibitory factor receptor (LIFR). Specifically, mouse OSM (mOSM) inhibited sclerostin production in a stromal cell line and in primary murine osteoblast cultures by acting through LIFR. In contrast, when acting through OSMR, mOSM stimulated RANKL production and osteoclast formation. A key role for OSMR in bone turnover was confirmed by the osteopetrotic phenotype of mice lacking OSMR. Furthermore, in contrast to the accepted model, in which mOSM acts only through OSMR, mOSM inhibited sclerostin expression in Osmr-/- osteoblasts and enhanced bone formation in vivo. These data reveal what we believe to be a novel pathway by which bone formation can be stimulated independently of bone resorption and provide new insights into OSMR and LIFR signaling that are relevant to other medical conditions, including cardiovascular and neurodegenerative diseases and cancer.

PMID: 20051625 [PubMed - indexed for MEDLINE]

In vivo detection of extrapancreatic insulin gene expression in diabetic mice by bioluminescence imaging.

PLoS One. 2010;5(2):e9397

Authors: Chen X, Larson CS, West J, Zhang X, Kaufman DB

BACKGROUND: Extrapancreatic tissues such as liver may serve as potential sources of tissue for generating insulin-producing cells. The dynamics of insulin gene promoter activity in extrapancreatic tissues may be monitored in vivo by bioluminescence-imaging (BLI) of transgenic mice Tg(RIP-luc) expressing the firefly luciferase (luc) under a rat-insulin gene promoter (RIP). METHODS: The Tg(RIP-luc) mice were made diabetic by a single injection of the pancreatic beta-cell toxin streptozotocin. Control mice were treated with saline. Mice were subject to serum glucose measurement and bioluminescence imaging daily. On day eight of the treatment, mice were sacrificed and tissues harvested for quantitative luciferase activity measurement, luciferase protein cellular localization, and insulin gene expression analysis. RESULTS: Streptozotocin-induced diabetic Tg(RIP-luc) mice demonstrated a dramatic decline in the BLI signal intensity in the pancreas and a concomitant progressive increase in the signal intensity in the liver. An average of 5.7 fold increase in the liver signal intensity was detected in the mice that were exposed to hyperglycemia for 8 days. Ex vivo quantitative assays demonstrated a 34-fold induction of the enzyme activity in the liver of streptozotocin-treated mice compared to that of the buffer-treated controls. Luciferase-positive cells with oval-cell-like morphology were detected by immunohistochemistry in the liver samples of diabetic mice, but not in that of non-treated control transgenic mice. Gene expression analyses of liver RNA confirmed an elevated expression of insulin genes in the liver tissue exposed to hyperglycemia. CONCLUSIONS: BLI is a sensitive method for monitoring insulin gene expression in extrapancreatic tissues in vivo. The BLI system may be used for in vivo screening of biological events or pharmacologic activators that have the potential of stimulating the generation of extrapancreatic insulin-producing cells.

PMID: 20195523 [PubMed - in process]

Protective effect of human amniotic fluid stem cells in an immunodeficient mouse model of acute tubular necrosis.

PLoS One. 2010;5(2):e9357

Authors: Perin L, Sedrakyan S, Giuliani S, Da Sacco S, Carraro G, Shiri L, Lemley KV, Rosol M, Wu S, Atala A, Warburton D, De Filippo RE

Acute Tubular Necrosis (ATN) causes severe damage to the kidney epithelial tubular cells and is often associated with severe renal dysfunction. Stem-cell based therapies may provide alternative approaches to treating of ATN. We have previously shown that clonal c-kit(pos) stem cells, derived from human amniotic fluid (hAFSC) can be induced to a renal fate in an ex-vivo system. Herein, we show for the first time the successful therapeutic application of hAFSC in a mouse model with glycerol-induced rhabdomyolysis and ATN. When injected into the damaged kidney, luciferase-labeled hAFSC can be tracked using bioluminescence. Moreover, we show that hAFSC provide a protective effect, ameliorating ATN in the acute injury phase as reflected by decreased creatinine and BUN blood levels and by a decrease in the number of damaged tubules and apoptosis therein, as well as by promoting proliferation of tubular epithelial cells. We show significant immunomodulatory effects of hAFSC, over the course of ATN. We therefore speculate that AFSC could represent a novel source of stem cells that may function to modulate the kidney immune milieu in renal failure caused by ATN.

PMID: 20195358 [PubMed - in process]

Species-specific activation of nuclear receptors correlates with the response of liver drug metabolizing enzymes to EMD 392949 in vitro.

Toxicol Lett. 2010 Mar 1;193(1):120-3

Authors: Mueller SO, Fery Y, Tuschl G, Schrenk D

We previously reported on the species-specific effects on drug metabolizing enzymes (DME), in particular cytochrome P450-dependent monooxygenases (P450s), by the drug development candidate EMD 392949 (EMD) in vitro and in vivo. Induction of P450s occurs via activation of specific transcription factors such as the arylhydrocarbon receptor (AhR) and the nuclear xenobiotic receptors (NXRs). We analyzed whether the reported species-specific P450 induction by EMD could be related to a specific activation of the CYP1A regulator AhR and the CYP3A regulator pregnane X receptor (PXR) in human and rat cell lines. The human HepG2 and rat H4IIE cell lines exhibited inducibility of CYP1A and 3A and expressed functional AhR as well as PXR. CYP3A was induced by EMD in human HepG2 cells exceeding the level induced by rifampicin, but was not induced in rat H4IIE cells. Regulation of P450s was not related to expression levels of their respective transcription factor, but EMD treatment resulted in a significant reporter gene activation in xenobiotic response enhancer module (XREM)-transfected HepG2 but not H4IIE cells indicating activation of human but not rat PXR. In summary, we showed that the P450 inducing properties of EMD were perfectly reflected by its ability to activate AhR or PXR in a species-specific manner. These findings support the tight correlation of species-specific nuclear receptor activation with P450 induction and foster the use of nuclear receptor activation as a complementary screen to identify cytochrome P450 inducers.

PMID: 20035846 [PubMed - indexed for MEDLINE]

Non-invasive detection of a small number of bioluminescent cancer cells in vivo.

PLoS One. 2010;5(2):e9364

Authors: Kim JB, Urban K, Cochran E, Lee S, Ang A, Rice B, Bata A, Campbell K, Coffee R, Gorodinsky A, Lu Z, Zhou H, Kishimoto TK, Lassota P

Early detection of tumors can significantly improve the outcome of tumor treatment. One of the most frequently asked questions in cancer imaging is how many cells can be detected non-invasively in a live animal. Although many factors limit such detection, increasing the light emission from cells is one of the most effective ways of overcoming these limitations. Here, we describe development and utilization of a lentiviral vector containing enhanced firefly luciferase (luc2) gene. The resulting single cell clones of the mouse mammary gland tumor (4T1-luc2) showed stable light emission in the range of 10,000 photons/sec/cell. In some cases individual 4T1-luc2 cells inserted under the skin of a nu/nu mouse could be detected non-invasively using a cooled CCD camera in some cases. In addition, we showed that only few cells are needed to develop tumors in these mice and tumor progression can be monitored right after the cells are implanted. Significantly higher luciferase activity in these cells allowed us to detect micrometastases in both, syngeneic Balb/c and nu/nu mice.

PMID: 20186331 [PubMed - in process]

Characterization of tailor-made copolymers of oligo(ethylene glycol) methyl ether methacrylate and N,N-dimethylaminoethyl methacrylate as nonviral gene transfer agents: influence of macromolecular structure on gene vector particle properties and transfection efficiency.

Biomacromolecules. 2010 Jan 11;11(1):39-50

Authors: Uzgün S, Akdemir O, Hasenpusch G, Maucksch C, Golas MM, Sander B, Stark H, Imker R, Lutz JF, Rudolph C

Oligo(ethylene glycol) methyl ether methacrylates (OEGMA) of various chain lengths (i.e., 9, 23, or 45 EG units) and N,N-dimethylaminoethyl methacrylate (DMAEMA) were copolymerized by atom transfer radical polymerization (ATRP), yielding well-defined P(DMAEMA-co-OEGMA) copolymers with increasing OEGMA molar fractions (F(OEGMA)) but a comparable degree of polymerization (DP approximately 120). Increase of both F(OEGMA) and OEGMA chain lengths correlated inversely with gene vector size, morphology, and zeta potential. P(DMAEMA-co-OEGMA) copolymers prevented gene vector aggregation at high plasmid DNA (pDNA) concentrations in isotonic solution and did not induce cytotoxicity even at high concentrations. Transfection efficiency of the most efficient P(DMAEMA-co-OEGMA) copolymers was found to be >10-fold lower compared with branched polyethylenimine (PEI) 25 kDa. Although OEGMA copolymerization largely reduced gene vector binding with the cell surface, cellular internalization of the bound complexes was less affected. These observations suggest that inefficient endolysosomal escape limits transfection efficiency of P(DMAEMA-co-OEGMA) copolymer gene vectors. Despite this observation, optimized p(DMAEMA-co-OEGMA) gene vectors remained stable under conditions for in vivo application leading to 7-fold greater gene expression in the lungs compared with PEI. Tailor-made P(DMAEMA-co-OEGMA) copolymers are promising nonviral gene transfer agents that fulfill the requirements for successful in vivo gene delivery.

PMID: 19957957 [PubMed - indexed for MEDLINE]

Mechanisms regulating repression of haptoglobin production by peroxisome proliferator-activated receptor-gamma ligands in adipocytes.

Endocrinology. 2010 Feb;151(2):586-94

Authors: Vernochet C, Davis KE, Scherer PE, Farmer SR

Obesity leads to inflammation of white adipose tissue involving enhanced secretion of cytokines and acute-phase proteins in response in part to the accumulation of excess lipids in adipocytes. Haptoglobin is an acute-phase reactant secreted by white adipose tissue and induced by inflammatory cytokines such as TNFalpha. In this study, we investigated the mechanisms regulating haptoglobin expression in adipocytes. Peroxisome proliferator-activated receptor (PPAR)-gamma agonists such as thiazolidinediones (TZDs) as well as non-TZD ligands can repress in vitro and in vivo haptoglobin expression in adipocytes and also prevent its induction by TNFalpha. This action requires direct involvement of PPAR gamma in regulating haptoglobin gene transcription because mutation of critical amino acids within helix 7 of the ligand-binding domain of PPAR gamma prevents repression of the haptoglobin gene by the synthetic ligands. Chromatin immunoprecipitation analysis shows active binding of PPAR gamma to a distal region of the haptoglobin promoter, which contains putative PPAR gamma binding sites. Additionally, PPAR gamma induces transcription of a luciferase reporter gene when driven by the distal promoter region of the haptoglobin gene, and TZD treatment significantly reduces the extent of this induction. Furthermore, the mutated PPAR gamma is incapable of enhancing luciferase activity in these in vitro reporter gene assays. In contrast to other adipokines repressed by TZDs such as resistin and chemerin, repression of haptoglobin does not require either CCAAT/enhancer-binding protein C/EBP alpha or the corepressors C-terminal binding protein 1 or 2. These data are consistent with a model in which synthetic PPAR gamma ligands selectively activate PPAR gamma bound to the haptoglobin gene promoter to arrest haptoglobin gene transcription.

PMID: 19952271 [PubMed - indexed for MEDLINE]

Bioluminescent approaches for measuring tumor growth in a mouse model of neurofibromatosis.

Toxicol Pathol. 2010;38(1):123-30

Authors: Hawes JJ, Reilly KM

Neurofibomatosis (NF1) patients are susceptible to multiple tumors of the nervous system including neurofibromas, optic glioma, malignant peripheral nerve sheath tumors (MPNSTs), and astrocytoma. The Nf1+/-;Trp53+/- (NPcis) mouse model of NF1 spontaneously develops astrocytoma and MPNSTs that are very similar to human NF1 tumors. To use this model for testing potential therapeutics, we have developed systems that take advantage of bioluminescent reporters of tumor growth. We have generated E2F1 promoter-driving luciferase (ELUX) reporter mice to detect proliferating tumors in NPcis mice in vivo using bioluminescence. The power of this system is that it enables looking at tumor evolution and detecting spontaneous tumors at early stages of development as they evolve within their natural haploinsufficient microenvironment. This system can be used to identify tumors at different stages of tumorigenesis and to examine where spontaneous NF1 tumors initiate. The ability to rapidly screen multiple animals at a time increases the potential for use of this model in preclinical trials. This model will be valuable for the characterization of spontaneous NF1 tumors and will be important for studying the treatment and prevention of NF1 tumors in vivo.

PMID: 20176786 [PubMed - in process]

Regulation of thyroid hormone activation via the LXR/RXR pathway.

J Endocrinol. 2010 Feb 22;

Authors: Christoffolete M, Doleschall M, Egri P, Liposits Z, Zavacki AM, Bianco A, Gereben B

Thyroid hormone (TR)- and liver X-receptors (LXR) are master regulators of lipid metabolism. Remarkably, a mouse with a targeted deletion of both LXR alpha and beta is resistant to Western diet-induced obesity, and exhibits ectopic liver expression of the thyroid hormone activating type 2 deiodinase (D2). We hypothesized that LXR/RXR signaling inhibits hepatic D2 expression, and studied this using a luciferase reporter containing the human DIO2 promoter (hDIO2) in HepG2 cells. Given that, in contrast to mammals, the chicken liver normally expresses D2, the chicken DIO2 promoter (cDIO2) was also studied. 22(R)-OH-cholesterol negatively regulated hDIO2 in a dose dependent manner (100 muM, ~2-fold), while it failed to affect the chicken DIO2 promoter. Truncations in the hDIO2 promoter identified the region -901 to -584 bp as critical for negative regulation. We also investigated if 9-cis retinoic acid (9-cis RA), the ligand for the heterodimeric partner of TR and LXR, RXR, could regulate the hDIO2 promoter. Notably, 9-cis RA repressed the hDIO2 luciferase reporter (1 muM, ~4-fold) in a dose-dependent manner, while co-expression of an inactive mutant RXR abolished this effect. However, it is unlikely that RXR homodimers mediate the repression of hDIO2 since mutagenesis of a DR-1 at -506 did not interfere with 9-cis RA-mediated repression. Our data indicates that hDIO2 transcription is negatively regulated by both 22(R)-OH-cholesterol and 9-cis RA, consistent with LXR/RXR involvement. In vivo, the inhibition of D2-mediated T3 production by cholesterol/9-cis RA could function as a feedback loop, given that T3 decreases hepatic cholesterol levels.

PMID: 20176747 [PubMed - as supplied by publisher]

Identification of the Cyclic AMP Responsive Element (CRE) that Mediates Transcriptional Regulation of the Pyruvate Carboxylase Gene in HepG2 cells.

Biochem Biophys Res Commun. 2010 Feb 17;

Authors: Thonpho A, Sereeruk C, Rojvirat P, Jitrapakdee S

Pyruvate carboxylase (PC) catalyzes the first committed step in gluconeogenesis. Here we investigated the effect of various hormones including cAMP, dexamethasone and insulin on the abundance of PC mRNA in the human hepatocyte cell line, HepG2. Treatment of HepG2 cells with 1 muM of glucagon increased the expression of PC mRNA 3-fold within 72 h. Treatment with 1 mM 8-Br-cAMP caused the abundance of PC mRNA to increase by 2-3-fold by 48 h, peak at 4-fold at 72 h, and remain unchanged to 96 h. This is in contrast to phosphoenolpyruvate carboxykinase (PEPCK) for which expression was decreased after 72 h, suggesting a distinct difference in the control of these two enzymes in the long term. Dexamethasone or insulin alone did not affect the abundance of PC mRNA whereas treatment of HepG2 cells with the combination of 1 mM 8-Br-cAMP and 0.5 muM dexamethasone further increased the abundance of PC mRNA, suggesting the predominant role of 8-Br-cAMP over dexamethasone. Transient transfection of the luciferase reporter construct driven by a 1.95 kbp 5'-flanking sequence of the mouse PC gene and a plasmid encoding the human cAMP-responsive element binding protein increased luciferase reporter activity to 7-8 fold similar to that observed with a PEPCK promoter-luciferase reporter construct. Deletion of the 5'-flanking region of the PC gene to 781 bp resulted in the complete loss of CREB-mediated induction of reporter gene, suggesting the presence of the cAMP-responsive unit is located between 1.95 kbp and 781 bp upstream of the mouse PC gene. Electrophoretic mobility shifted and chromatin immunoprecipitation assays demonstrated that CREB bind to -1639/-1631 CRE of mouse PC gene in vitro and in vivo, respectively.

PMID: 20171190 [PubMed - as supplied by publisher]

Methods for evaluating effects of an irinotecan + 5-fluorouracil/leucovorin (IFL) regimen in an orthotopic metastatic colorectal cancer model utilizing in vivo bioluminescence imaging.

Methods Mol Biol. 2010;602:235-52

Authors: Surguladze D, Steiner P, Prewett M, Tonra JR

In testing novel anticancer therapies, researchers strive to utilize models that reflect the human disease as much as feasible. In this regard, orthotopic models are frequently developed because cancer cells in these models form tumors in, and metastasize from, a tissue environment similar to the tissue of origin of the cancer cells. Here we adapted an orthotopic colorectal cancer model, in which HT-29 colorectal cancer cells form tumors in the rectal lining and metastasize to the para-aortic lymph nodes with high frequency. Firefly luciferase-expressing HT-29 cells were used in this model to realize the benefits of bioluminescence imaging (BLI). A combination of irinotecan, 5-fluorouracil (5-FU), and leucovorin (LV) (IFL) was used as a standard chemotherapeutic regimen positive control. BLI allowed for the demonstration of the effects of IFL on tumor growth in the rectal lining, with tumor weight measurements at the end of the study reflecting total tumor burden. BLI also allowed relatively easy demonstration of reduced tissue metastasis with IFL treatment, compared to more time-consuming histological techniques. It is concluded that the orthotopic colorectal cancer model approach described represents a valuable tool for validating treatment strategies in this indication.

PMID: 20012402 [PubMed - indexed for MEDLINE]

Potent antitumor effects of combined therapy with a telomerase-specific, replication-competent adenovirus (OBP-301) and IL-2 in a mouse model of renal cell carcinoma.

Cancer Gene Ther. 2010 Feb 19;

Authors: Huang P, Kaku H, Chen J, Kashiwakura Y, Saika T, Nasu Y, Urata Y, Fujiwara T, Watanabe M, Kumon H

OBP-301 (a telomerase-specific, replication-competent adenovirus with hTERT promoter) was constructed in a previous study and it showed a strong anticancer effect by inducing cell lysis in human lung and prostate cancer cells. This study investigated the effectiveness of a combination therapy of OBP-301 and interleukin-2 (IL-2) in a mouse model of renal cell carcinoma (RCC). The cell-killing effect of OBP-301 was confirmed in vitro in the RENCA cancer cells. In in vivo experiment, luciferase-expressing RENCA cells were implanted in the left kidney and lung of BALB/c mice to prepare the RCC metastatic model. The animals were randomly divided into four treatment groups: PBS, IL-2 alone, OBP-301 alone and the combination. The analyses of orthotopic tumor weight, lung metastasis and luciferin-stained tumor images 14 days after each treatment showed significant tumor growth inhibition in the combination group in comparison with that in the OBP-301- or IL-2-treated groups. In addition, the percentage of regulatory T-cells (Tregs) in the combination group was significantly suppressed in comparison with that in the PBS and single-agent treatment groups. The outcomes of this study suggest that tumor-specific oncolytic immunovirotherapy may become an attractive strategy for the treatment of human RCC.Cancer Gene Therapy advance online publication, 19 February 2010; doi:10.1038/cgt.2010.5.

PMID: 20168351 [PubMed - as supplied by publisher]

Zac1 Is an Essential Transcription Factor for Cardiac Morphogenesis.

Circ Res. 2010 Feb 18;

Authors: Yuasa S, Onizuka T, Shimoji K, Ohno Y, Kageyama T, Yoon SH, Egashira T, Seki T, Hashimoto H, Nishiyama T, Kaneda R, Murata M, Hattori F, Makino S, Sano M, Ogawa S, Prall OW, Harvey RP, Fukuda K

Rationale: The transcriptional networks guiding heart development remain poorly understood, despite the identification of several essential cardiac transcription factors. Objective: To isolate novel cardiac transcription factors, we performed gene chip analysis and found that Zac1, a zinc finger-type transcription factor, was strongly expressed in the developing heart. This study was designed to investigate the molecular and functional role of Zac1 as a cardiac transcription factor. Methods and Results: Zac1 was strongly expressed in the heart from cardiac crescent stages and in the looping heart showed a chamber-restricted pattern. Zac1 stimulated luciferase reporter constructs driven by ANF, BNP, or alphaMHC promoters. Strong functional synergy was seen between Zac1 and Nkx2-5 on the ANF promoter, which carries adjacent Zac1 and Nkx2-5 DNA-binding sites. Zac1 directly associated with the ANF promoter in vitro and in vivo, and Zac1 and Nkx2-5 physically associated through zinc fingers 5 and 6 in Zac1, and the homeodomain in Nkx2-5. Zac1 is a maternally imprinted gene and is the first such gene found to be involved in heart development. Homozygous and paternally derived heterozygous mice carrying an interruption in the Zac1 locus showed decreased levels of chamber and myofilament genes, increased apoptotic cells, partially penetrant lethality and morphological defects including atrial and ventricular septal defects, and thin ventricular walls. Conclusions: Zac1 plays an essential role in the cardiac gene regulatory network. Our data provide a potential mechanistic link between Zac1 in cardiogenesis and congenital heart disease manifestations associated with genetic or epigenetic defects in an imprinted gene network.

PMID: 20167925 [PubMed - as supplied by publisher]

Luciferase therapeutic microcapsules for gene therapy.

Artif Cells Blood Substit Immobil Biotechnol. 2009;37(6):235-44

Authors: Li AA, Hou DY, Shen F, Seidlitz EP, Potter MA

MDCK cells were engineered to express luciferase driven by cytomegalovirus (CMV) or hybrid ubiquitin B (UbB) promoter and encapsulated in alginate-poly-L-lysine-alginate microcapsules. In vitro experiments showed capsules could be monitored individually or in multi-layers quantitatively. When luciferase-expressing and non-luciferase expressing MDCK cells were mixed at different ratios and encapsulated, the signals increased linearly according to the number of capsules, in vitro and in vivo. For CMV-driven luciferase expression, the strongest signal was seen at 4 hours post-implantation, with a subsequent 50% decrease by 24 hours and then declined gradually to 10-20% until day 20. However, retrieved capsules showed good cell viability. When capsules contained plasmid driven by UbB promoter, there was no decline in signal. Our results indicate that luciferase could be used as a marker for microencapsulated cells to monitor the viability and gene expression of the implanted cells.

PMID: 19922164 [PubMed - indexed for MEDLINE]

Manipulating prohibitin levels provides evidence for an in vivo role in androgen regulation of prostate tumours.

Endocr Relat Cancer. 2009 Dec;16(4):1157-69

Authors: Dart DA, Spencer-Dene B, Gamble SC, Waxman J, Bevan CL

Current hormonal therapies for prostate cancer are effective initially, but inevitably tumours progress to an advanced, metastatic stage, often referred to as 'androgen independent'. However, the androgen receptor (AR) signalling pathway is still key for their growth. It is speculated that tumours escape hormonal control via reduction in corepressor proteins. Manipulating such proteins is thus a potential therapeutic strategy to halt or even reverse tumour progression. We aimed to elucidate the effects of altering levels of the AR corepressor and androgen-target protein prohibitin (PHB) on prostate tumour growth. Prostate cancer cells incorporating an integrated androgen-responsive reporter gene and stably expressing vectors to inducibly overexpress or knockdown PHB were generated and used to assess effects on androgen signalling (by real time imaging) and tumour growth both in culture and in vivo. PHB overexpression inhibited AR activity and prostate-specific antigen (PSA) expression as well as androgen-dependent growth of cells, inducing rapid accumulation in G(0)/G(1). Conversely, reduction in PHB increased AR activity, PSA expression, androgen-mediated growth and S-phase entry. In vivo, doxycycline-induced PHB regulation resulted in marked changes in AR activity, and showed significant effects upon tumour growth. Overexpression led to tumour growth arrest and protection from hormonal starvation, whereas RNAi knockdown resulted in accelerated tumour growth, even in castrated mice. This study provides proof of principle that i) reduction in PHB promotes both androgen-dependent and 'androgen-independent' tumour growth, and ii) altering AR activity via increasing levels or activity of corepressors is a valid therapeutic strategy for advanced prostate cancer.

PMID: 19635783 [PubMed - indexed for MEDLINE]

Normal thermoregulatory responses to 3-iodothyronamine, trace amines and amphetamine-like psychostimulants in trace amine associated receptor 1 knockout mice.

J Neurosci Res. 2010 Feb 12;

Authors: Panas HN, Lynch LJ, Vallender EJ, Xie Z, Chen GL, Lynn SK, Scanlan TS, Miller GM

3-Iodothyronamine (T1AM) is a metabolite of thyroid hormone. It is an agonist at trace amine-associated receptor 1 (TAAR1), a recently identified receptor involved in monoaminergic regulation and a potential novel therapeutic target. Here, T1AM was studied using rhesus monkey TAAR1 and/or human dopamine transporter (DAT) co-transfected cells, and wild-type (WT) and TAAR1 knock-out (KO) mice. The IC(50) of T1AM competition for binding of the DAT-specific radio-ligand [(3)H]CFT was highly similar in DAT cells, WT striatal synaptosomes and KO striatal synaptosomes (0.72-0.81 muM). T1AM inhibition of 10 nM [(3)H]dopamine uptake (IC(50): WT, 1.4 +/- 0.5 muM; KO, 1.2 +/- 0.4 muM) or 50 nM [(3)H]serotonin uptake (IC(50): WT, 4.5 +/- 0.6 muM; KO, 4.7 +/- 1.1 muM) in WT and KO synaptosomes was also highly similar. Unlike other TAAR1 agonists that are DAT substrates, TAAR1 signaling in response to T1AM was not enhanced in the presence of DAT as determined by CRE-luciferase assay. In vivo, T1AM induced robust hypothermia in WT and KO mice equivalently and dose dependently (maximum change degrees Celsius: 50 mg/kg at 60 min: WT -6.0 +/- 0.4, KO -5.6 +/- 1.0; and 25 mg/kg at 30 min: WT -2.7 +/- 0.4, KO -3.0 +/- 0.2). Other TAAR1 agonists including beta-phenylethylamine (beta-PEA), MDMA (3,4-methylenedioxymethamphetamine) and methamphetamine also induced significant, time-dependent thermoregulatory responses that were alike in WT and KO mice. Therefore, TAAR1 co-expression does not alter T1AM binding to DAT in vitro nor T1AM inhibition of [(3)H]monoamine uptake ex vivo, and TAAR1 agonist-induced thermoregulatory responses are TAAR1-independent. Accordingly, TAAR1-directed compounds will likely not affect thermoregulation nor are they likely to be cryogens. (c) 2010 Wiley-Liss, Inc.

PMID: 20155805 [PubMed - as supplied by publisher]

Inhibition of cancer cell proliferation and metastasis by insulin receptor downregulation.

Oncogene. 2010 Feb 15;

Authors: Zhang H, Fagan DH, Zeng X, Freeman KT, Sachdev D, Yee D

Insulin receptor (IR) and the type I IGF receptor (IGF1R) are structurally and functionally related. The function of IGF1R in cancer has been well documented and anti-IGF1R strategies to treat cancer have shown initial positive results. However, the role of IR in tumor biology, independent of IGF1R, is less clear. To address this issue, short hairpin RNA (shRNA) was used to specifically downregulate IR in two cancer cell lines, LCC6 and T47D. Cells with reduced IR showed reduced insulin-stimulated Akt activation, without affecting IGF1R activation. Cells with reduced IR formed fewer colonies in anchorage-independent conditions. LCC6 IR shRNA xenograft tumors in mice had reduced growth, angiogenesis and lymphangiogensis when compared with LCC6 wild-type cells. Accordingly, LCC6 IR shRNA clones produced less hypoxia-inducible factor-1alpha, vascular endothelial growth factor (VEGF)-A and VEGF-D. Furthermore, LCC6 IR shRNA cells formed fewer pulmonary metastases when compared with LCC6 wild-type cells. Using in vivo luciferase imaging, we have shown that LCC6 IR shRNA cells have less seeding and colonization potential in the lung and liver of mice than LCC6 cells. In conclusion, downregulation of IR inhibited cancer cell proliferation, angiogenesis, lymphangiogenesis and metastasis. Our data argue that IR should also be targeted in cancer therapy.Oncogene advance online publication, 15 February 2010; doi:10.1038/onc.2010.17.

PMID: 20154728 [PubMed - as supplied by publisher]