Doxycycline modulates VEGF-A expression: Failure of doxycycline-inducible lentivirus shRNA vector to knockdown VEGF-A expression in transgenic mice - Fig 3

<p><b>Plasma VEGF-A concentration in response to dox treatment (a). Tissue VEGF-A mRNA and protein levels after two weeks of 1 mg/ml dox treatment and five weeks of 2 mg/ml dox dose treatment (b-k).</b> Dox treatment decreased plasma VEGF-A levels in TG mice after 1 week, after which the plasma VEGF-A increased. In WT mice a decreasing effect on plasma VEGF-A was seen (a). *p<0.05, **p<0.01 and ***p<0.001 compared to baseline within each group, 1-way ANOVA with Dunnett´s post hoc test, n = 9-10/group. In the selected tissues, aorta, heart and kidney, the dox treatment with the 1 mg/ml dox dose for 2 weeks showed decreasing trend in VEGF-A mRNA expression in TG mice in comparison to WT mice (b, d, h), which was associated with increased cardiac VEGF-A protein (e) and decreased kidney VEGF-A protein levels (i). When the dox dose was doubled and the treatment time increased to 5 weeks, a trend towards increasing VEGF-A expression was seen in all three tissues in both WT and TG mice (c, f, j). However, no changes were detected in protein levels (g, k). **p<0.01 and ***p<0.001 compared to WT+dox group in 2 weeks experiment (b, d, e, h, i) or to no dox group (-dox) in 5 weeks experiment (c, f, g, j, k), <i>t-test</i>, n = 6-24/group.</p

VEGF-A knockdown via RNAi in mouse endothelial cells and cardiomyocytes in a doxycycline-regulatable fashion.

<p>Secreted VEGF-A protein amount was most efficiently decreased with sh1 -knockdown vector (T-1 and TT-1) in mouse endothelial cells in comparison to sh2 (T-2 and TT-2) and sh3 (T-3 and TT-3) vectors. With the sh1 construct the normal TRE promoter (T-1) seemed to be slightly more efficient and less leaky than the tight TRE promoter (TT-1) (a). The magnitude of VEGF-A knockdown with the selected T-1 vector increased with increasing dox doses in endothelial cells (b). With the increasing dox doses also the amount of Venus expressing cells (%) was increased as follows: 40 ± 7% (–dox), 46 ± 8% (dox 10 ng/ml), 85 ± 3% (dox 100 ng/ml) and 78 ± 2% (dox 1000 ng/ml) (c). In cardiomyocytes the knockdown of VEGF-A with the T-1 vector was shown to be dependent of the amount of virus (MOI) and dox exposure time and the decrease was larger at the cellular level in comparison to the secreted protein (d-e). Results are shown as mean ± S.D., n = 3/group. The percentage of VEGF-A protein concentration compared to control +dox group (a) or non-transduced (NT) group (b, d, e) are shown above bars. *p<0.05, **p<0.01 and ***p<0.001 compared to control +dox group (a) or non-transduced (NT) group (b, d, e), 1-way ANOVA with Dunnett´s post hoc test. NT = non-transduced cells, MOI = multiplicity of infection, Contr = Control lentivirus vector targeting Luciferase. Scale bar 200 μm (c).</p

Schematic drawing of the dox-regulatable VEGF-A shRNA lentivirus vector.

<p>Lentivirus vector for inducible knockdown permits constitutive expression of a Tet-transactivating component (rtTA3) with a Venus selection marker (green fluorescent protein -like protein) and tetracycline-regulated expression of VEGF-A-shRNAs. The shRNA transcripts were designed as primary microRNA mimics i.e. they were embedded in the primary transcript of human miRNA30. The lentiviruses were self-inactivating (SIN) third generation vectors, in which part of the viral 3´LTR has been deleted preventing the viral replication. The vectors contain a central polypurine tract (indicated as FLAP) for enhancement of viral titers and a woodchuck hepatitis virus posttranscriptional regulatory element (WRE) for better transgene expression [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190981#pone.0190981.ref024" target="_blank">24</a>].</p

Epigenetic Upregulation of Endogenous VEGF-A Reduces Myocardial Infarct Size in Mice

<div><p>“Epigenetherapy” alters epigenetic status of the targeted chromatin and modifies expression of the endogenous therapeutic gene. In this study we used lentiviral <i>in vivo</i> delivery of small hairpin RNA (shRNA) into hearts in a murine infarction model. shRNA complementary to the promoter of vascular endothelial growth factor (VEGF-A) was able to upregulate endogenous VEGF-A expression. Histological and multiphoton microscope analysis confirmed the therapeutic effect in the transduced hearts. Magnetic resonance imaging (MRI) showed <i>in vivo</i> that the infarct size was significantly reduced in the treatment group 14 days after the epigenetherapy. Importantly, we show that promoter-targeted shRNA upregulates all isoforms of endogenous VEGF-A and that an intact hairpin structure is required for the shRNA activity. In conclusion, regulation of gene expression at the promoter level is a promising new treatment strategy for myocardial infarction and also potentially useful for the upregulation of other endogenous genes.</p></div

Intracellular distribution of LV-451 expressed RNA and VEGF-A mRNA in transduced cells.

<p>C166 cells were subjected to RNA-FISH analysis with LV-451 or VEGF mRNA probes. (a) Confocal microscopy images of LV-451 transduced (MOI 10) cells 72 h post transduction. Distribution of LV-451 RNA (green) and VEGF-A mRNA (red) probe binding induced signals is shown. Nuclei were visualized with DAPI (grey). Scale bars, 5 µm. (b) Quantification of LV-451 RNA or VEGF-A mRNA RNA-FISH signal spots detected in LV-451 transduced (MOI 4, 40, 200) cells at 72 h post transduction and in nontransduced control cells. The amount of signal was calculated in the nucleus (white), the cytosol (grey) and whole cell (black). Error bars = SD. (c) Nucleus size in response to LV transduction. CTRL sample is nontransduced C166 cells and LV-451 is C166 cells transduced with LV-451 vector.</p

Analysis for mechanism of action for promoter targeted shRNAs.

<p>(a) RT-PCR analysis for different VEGF-A isoforms. The expression levels for different isoforms were studied using primers specific to each isoform. Total VEGF-A protein level was measured with ELISA. (b) Reversing DNA methylation with 5-Azacytidine treatment induces responses in MS1 cells but erases responses in C166 cells. Cells were treated with 1 µM 5-Azacytidine, transduced with different vectors on day 3 and samples were collected on day 8. qRT-PCR analysis of VEGF-A and B-actin mRNA levels in MS1 cells and C166 cells. (c) qChIP assay in MS1 cells using antibody against H3K27me3. (d) The VEGF-A gene promoter in C166 cells was also analyzed for basal DNA methylation levels without 5-Azacytidine treatment using MeDIP. Cells were transduced with different vectors using MOI 10, 10 days timepoint. (e) RT-PCR analysis of VEGF-A mRNA levels after C166 cells were transfected with siRNA oligos. Results are calculated in reference to housekeeping gene ACTB and control oligo. (f) CBP-CREB interaction inhibitor (7.5 µM) abolishes the upregulation of VEGF-A by LV-451 in C166 cells. For all results, mean ± SD shown.</p

Multiphoton microscopy and histology analysis of myocardial infarction animals.

<p>(a) Multiphoton laser scanning microscopy (MPLSM) analysis of GFP expression in transduced mouse heart, (b) Immunohistological analysis of GFP expression in mouse heart, (c) antibody omitted control, (d and k) Massons Trichrome staining from mouse heart transduced with VEGF-A upregulating LV-451 and shRNA control, respectively, (e and l) insert from infarcted area of d and k, respectively, (h and o) insert from infarct borderzone (f, i, m, p) alpha-SMA staining of smooth muscle cells, arrows point to arteriols formed, (g, j, n, q) CD-31 staining of endothelial cells. Scale bars (a) 100 µm, (d and k) 2000 µm, (e, f, g, h, i, j, l, m, n, o, p, q) 200 µm.</p

ELISA assay of myocardial infarction samples and analysis for single-stranded vectors for a mechanistical view.

<p>(a) ELISA analysis of VEGF-A protein from transduced hearts, (b) ELISA assay from growth medium of C166 cells transduced with LV-451 and corresponding single stranded vectors using MOI 10, 7 days time point. (c) RT-PCR analysis of VEGF-A mRNA levels. C166 cells were transduced with LV-451 and corresponding single stranded vectors using MOI 10, 11 days time point. (d) qChIP assay of C166 cells using antibodies against H3K4me2. Cells were transduced with LV-451 and corresponding single stranded vectors using MOI 10, 11 days timepoint. All results are shown as mean ± SD.</p

MRI analysis of murine myocardial infarction.

<p>Infarct size in VEGF-A upregulated (shRNA) and in control (shRNA Control) groups measured using MRI (a), and representative examples of short axis cine images with outlined (red lines) infarcts in late diastole at days 4 and 14 in both shRNA and shRNA control animals (b).</p