Insulin-like growth factor-1 (IGF-1) has been found to exert favorable effects on angiogenesis in prior animal studies. This study explored the long-term effect of IGF-1 on angiogenesis using microSPECT-CT in infarcted rat hearts after delivering human IGF-1 gene by adeno-associated virus (AAV). Myocardial infarction (MI) was induced in Sprague-Dawley rats by ligation of the proximal anterior coronary artery and a total of 1011 AAV-CMV-LacZ (control) or IGF-1 vectors were injected around the peri-infarct area. IGF-1 expression by AAV stably transduced heart muscle for up to 16 weeks post-MI and immunohistochemistry revealed a remarkable increase in capillary density. A 99m Tc-labeled RGD peptide (NC100692, GE Healthcare) was used to assess temporal and regional αv integrin activation. Rats were injected with NC100692 followed by 201 Tl chloride and in vivo microSPECT-CT imaging was performed. After imaging, hearts were excised and cut for quantitative gamma-well counting (GWC). NC100692 retention was significantly increased in hypoperfused regions of both LacZ and IGF-1 rats at 4 and 16 weeks post-MI. Significantly higher activation of αv integrin was observed in IGF-1 rats at 4 weeks post treatment compared with control group, although the activation was lower in the IGF-1 group at 16 weeks.Local IGF-1 gene delivery by AAV can render a sustained transduction and improve cardiac function post-MI. IGF-1 expression contributes to enhanced αv integrin activation which is linked to angiogenesis. MicroSPECT-CT imaging with 99m Tc-NC100692 and quantitative GWC successfully assessed differences in αv integrin activation between IGF-1 treated and control animals post-MI.Crown

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The regenerative potential of bone marrow-derived endothelial progenitor cells (EPCs) has been adapted for the treatment of myocardial and limb ischemia via ex vivo expansion. We sought to enhance EPC function by the efficient genetic modification of EPCs in a rat model of myocardial infarction. Peripheral blood EPCs were expanded and transduced, using adeno-associated virus (AAV). AAV-mediated EPC transduction efficacy was 23 ± 1.2%, which was improved by 4.0- to 7.2-fold after pretreatment with the tyrosine kinase inhibitor genistein. Adult rats (n = 7 in each group) underwent myocardial infarction by left anterior descending coronary artery occlusion, and received autologous EPCs transduced by AAV-IGF-1 or AAV-lacZ into the periinfarct area. Echocardiography demonstrated that cardiac function in the IGF-1-EPC group was significantly improved compared with the lacZ-EPC control group 12 weeks after myocardial infarction. In addition, IGF-1-expressing EPCs led to reduced cardiac apoptosis, increased cardiomyocyte proliferation, and increased numbers of capillaries in the periinfarct area. AAV expression was limited to the targeted heart region only. Pretreatment with genistein markedly improved AAV transduction of EPCs. IGF-1-expressing EPCs exhibit favorable cell-protective effects with tissue-limited expression in rat heart postinfarction.

Ileal bile acid binding protein (IBABP) is the only cytosolic protein known to bind and transport bile acids. Because IBABP is reportedly up-regulated in colorectal cancer, it has been suggested as a link between bile acids and the risk of colorectal cancer. However, in this study, we show that IBABP is not up-regulated. Rather, a novel transcript of the IBABP gene, which encodes an additional 49 NH 2 -terminal amino acid residues, is up-regulated in colorectal cancer (P < 0.001). The novel transcript, called IBABP-L, is also distinct from IBABP because its transcription is controlled by nuclear factor-KB (NF-KB) rather than by the farnesoid X receptor. Most significantly, IBABP-L is necessary for the survival of HCT116 colon cancer cells in the presence of physiologic levels of the secondary bile acid deoxycholate. Collectively, the studies point toward a unique bile acid response pathway involving NF-KB and IBABP-L that could be useful for diagnosis and could potentially be targeted for therapeutic benefit.

Recombinant adeno-associated virus (rAAV) vectors represent a promising approach to gene delivery for clinical use. Published data indicate that rAAV vector genomes persist in vivo as episomal chromatin in the skeletal muscle of nonhuman primates. In this study, we assessed the interconnection between the transcription factor cyclic AMP response element-binding protein (CREB) and recombinant AAV serotype 2 vector genomes after transduction in vitro and in vivo. rAAV-mediated myocyte transduction was potently blocked in the hearts of mice expressing CREB-S133A, which is a CREB-S133A dominant-negative mutant. Isoproterenol, a strong CREB activator, prominently increased rAAV transduction and the increase was abrogated by silencing the CREB gene with small interfering RNA. In addition, rAAV infection of muscle cells mildly but significantly induced CREB protein phosphorylation at serine-133, and was capable of stimulating CREB-dependent transcription from a reporter plasmid. Using chromatin immunoprecipitation and immunoblotting assays, both CREB and p300 were found to physically associate with two different rAAV genomes. Accordingly, CREB/p300 appears to have a role in rAAV transduction to establish active vector transcription in heart muscle cells.

No abstract

Recombinant adeno-associated virus (rAAV)-based gene therapy represents a promising approach for the treatment of heart muscle diseases, but the molecular mechanisms that direct rAAV transduction remain unclear. Here we demonstrate that β-adrenergic receptor stimulation with isoproterenol (ISO) markedly increased cardiomyocyte transduction of rAAV in vitro and in vivo. Conversely, chronic β-adrenergic receptor downregulation significantly suppressed rAAV transduction. Pretreatment with calcium signaling cascade inhibitors including calcineurin inhibitory peptide (CNIP) strongly suppressed the positive effects of ISO on rAAV transduction. Additionally we document that ISO treatment led to a significant increase in double-stranded (ds) DNA synthesis of the rAAV genome and an increase in promoter activity. Moreover, stimulation with ISO did not affect rAAV transduction in calcineurin nullizygous mice. Collectively, we conclude that a calcium-dependent pathway regulates rAAV vector transduction at a number of stages that may include vector mobilization, conversion, and transcription activity. Modulating this pathway through β-adrenergic signaling enhances rAAV-mediated gene delivery to cardiomyocytes, and may be valuable when considering therapeutic approaches for heart muscle diseases.

<div>Abstract<p>Ileal bile acid binding protein (IBABP) is the only cytosolic protein known to bind and transport bile acids. Because IBABP is reportedly up-regulated in colorectal cancer, it has been suggested as a link between bile acids and the risk of colorectal cancer. However, in this study, we show that IBABP is not up-regulated. Rather, a novel transcript of the <i>IBABP</i> gene, which encodes an additional 49 NH₂-terminal amino acid residues, is up-regulated in colorectal cancer (<i>P</i> < 0.001). The novel transcript, called IBABP-L, is also distinct from IBABP because its transcription is controlled by nuclear factor-κB (NF-κB) rather than by the farnesoid X receptor. Most significantly, IBABP-L is necessary for the survival of HCT116 colon cancer cells in the presence of physiologic levels of the secondary bile acid deoxycholate. Collectively, the studies point toward a unique bile acid response pathway involving NF-κB and IBABP-L that could be useful for diagnosis and could potentially be targeted for therapeutic benefit. [Cancer Res 2007;67(19):9039–46]</p></div>