Publications

Expression of angiogenesis‐related molecules in plexiform lesions in severe pulmonary hypertension: evidence for a process of disordered angiogenesis

Abstract Pulmonary arteries of patients with severe pulmonary hypertension (SPH) presenting in an idiopathic form (primary PH‐PPH) or associated with congenital heart malformations or collagen vascular diseases show plexiform lesions. It is postulated that in lungs with SPH, endothelial cells in plexiform lesions express genes encoding for proteins involved in angiogenesis, in particular, vascular endothelial growth factor (VEGF) and those involved in VEGF receptor‐2 (VEGFR‐2) signalling. On immunohistochemistry and in situ hybridization, endothelial cells in the plexiform lesions expressed VEGF mRNA and protein and overexpressed the mRNA and protein of VEGFR‐2, and the transcription factor subunits HIF‐1α and HIF‐1β of hypoxia inducible factor, which are responsible for the hypoxia‐dependent induction of VEGF. When compared with normal lungs, SPH lungs showed decreased expression of the kinases PI3 kinase and src, which, together with Akt, relay the signal transduction downstream of VEGFR‐2. Because markers of angiogenesis are expressed in plexiform lesions in SPH, it is proposed that these lesions may form by a process of disordered angiogenesis. Copyright © 2001 John Wiley & Sons, Ltd.

Elevated Expression of Angiopoietin-like 4 in the Aqueous of Retinal Vein Occlusion Patients Who Develop Neovascular Glaucoma

PHD3-mediated prolyl hydroxylation of nonmuscle actin impairs polymerization and cell motility

Actin filaments play an essential role in cell movement, and many posttranslational modifications regulate actin filament assembly. Here we report that prolyl hydroxylase 3 (PHD3) interacts with nonmuscle actin in human cells and catalyzes hydroxylation of actin at proline residues 307 and 322. Blocking PHD3 expression or catalytic activity by short hairpin RNA knockdown or pharmacological inhibition, respectively, decreased actin prolyl hydroxylation. PHD3 knockdown increased filamentous F-actin assembly, which was reversed by PHD3 overexpression. PHD3 knockdown increased cell velocity and migration distance. Inhibition of PHD3 prolyl hydroxylase activity by dimethyloxalylglycine also increased actin polymerization and cell migration. These data reveal a novel role for PHD3 as a negative regulator of cell motility through posttranslational modification of nonmuscle actins.

Regulation of cancer cell metabolism by hypoxia-inducible factor 1

Reversible inhibition of hypoxia‐inducible factor 1 activation by exposure of hypoxic cells to the volatile anesthetic halothane

Volatile anesthetics modulate a variety of physiological and pathophysiological responses including hypoxic responses. Hypoxia‐inducible factor 1 (HIF‐1) is a transcription factor that mediates cellular and systemic homeostatic responses to reduced O 2 availability in mammals, including erythropoiesis, angiogenesis, and glycolysis. We demonstrate for the first time that the volatile anesthetic halothane blocks HIF‐1 activity and downstream target gene expressions induced by hypoxia in the human hepatoma‐derived cell line, Hep3B. Halothane reversibly blocks hypoxia‐induced HIF‐1α protein accumulation and transcriptional activity at clinically relevant doses.

Regulation of tumor angiogenesis by p53-induced degradation of hypoxia-inducible factor 1alpha.

The switch to an angiogenic phenotype is a fundamental determinant of neoplastic growth and tumor progression. We demonstrate that homozygous deletion of the p53 tumor suppressor gene via homologous recombination in a human cancer cell line promotes the neovascularization and growth of tumor xenografts in nude mice. We find that p53 promotes Mdm2-mediated ubiquitination and proteasomal degradation of the HIF-1alpha subunit of hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor that regulates cellular energy metabolism and angiogenesis in response to oxygen deprivation. Loss of p53 in tumor cells enhances HIF-1alpha levels and augments HIF-1-dependent transcriptional activation of the vascular endothelial growth factor (VEGF) gene in response to hypoxia. Forced expression of HIF-1alpha in p53-expressing tumor cells increases hypoxia-induced VEGF expression and augments neovascularization and growth of tumor xenografts. These results indicate that amplification of normal HIF-1-dependent responses to hypoxia via loss of p53 function contributes to the angiogenic switch during tumorigenesis.

Regulation of carotid body oxygen sensing by hypoxia-inducible factors

Blood vessels, disease pathogenesis, and novel therapies

Supplementary Data from Hypoxia-Induced Suppression of Alternative Splicing of MBD2 Promotes Breast Cancer Metastasis via Activation of FZD1

<p>Supplementary Figures: Figure S1. MBD2a and MBD2c exert opposing roles in BrCa cell migration. Figure S2. Hypoxia inhibits SRSF2-mediated MBD2 splicing. Figure S3. MBD2a and MBD2c inversely regulate EMT markers. Figure S4. DNA methylation controls MBD2-mediated FZD1 transcription. Figure S5. The effect of MBD2a and MBD2c on breast tumor growth in vivo. Supplementary Tables: Table S1, DAVID analysis of the co-regulated genes. Table S2, Metastasis-related Genes with altered expression according to RNA-seq data involved in cell migration. Table S3, DAVID analysis of the co-regulated and co-bound genes. Table S4, Primers used for quantification of mRNA and genome DNA. Table S5, Information of antibody, chemical reagent, cell line and software.</p>

HIF-1: mediator of physiological and pathophysiological responses to hypoxia

All organisms can sense O 2 concentration and respond to hypoxia with adaptive changes in gene expression. The large body size of mammals necessitates the development of multiple complex physiological systems to ensure adequate O 2 delivery to all cells under normal conditions. The transcriptional regulator hypoxia-inducible factor 1 (HIF-1) is an essential mediator of O 2 homeostasis. HIF-1 is required for the establishment of key physiological systems during development and their subsequent utilization in fetal and postnatal life. HIF-1 also appears to play a key role in the pathophysiology of cancer, cardiovascular disease, and chronic lung disease, which represent the major causes of mortality among industrialized societies. Genetic or pharmacological modulation of HIF-1 activity in vivo may represent a novel therapeutic approach to these disorders.

Hypoxic retinal Müller cells promote vascular permeability by HIF-1–dependent up-regulation of angiopoietin-like 4

Significance Ischemic retinopathies include a diverse group of diseases in which immature retinal vasculature or damage to mature retinal vessels leads to retinal ischemia. The anticipated rise in the worldwide prevalence of diabetes will result in a concurrent increase in the number of patients with vision impairment from diabetic eye disease, the most common cause of ischemic retinopathy. We set out to identify novel hypoxia-inducible genes that promote vascular permeability and may therefore play a role in the pathogenesis of diabetic eye disease. We demonstrate that angiopoietin-like 4 (ANGPTL4) is up-regulated by the transcriptional enhancer, hypoxia-inducible factor-1 in hypoxic retinal Müller cells, and can promote vascular permeability. Our findings suggest that ANGPTL4 may be a potential therapeutic target for ischemic retinopathies.

Sirtuin-7 Inhibits the Activity of Hypoxia-inducible Factors

Hypoxia-inducible factor (HIF) 1 and HIF-2 are heterodimeric proteins composed of an oxygen-regulated HIF-1α or HIF-2α subunit, respectively, and a constitutively expressed HIF-1β subunit, which mediate adaptive transcriptional responses to hypoxia. Here, we report that Sirt7 (sirtuin-7) negatively regulates HIF-1α and HIF-2α protein levels by a mechanism that is independent of prolyl hydroxylation and that does not involve proteasomal or lysosomal degradation. The effect of Sirt7 was maintained in the presence of the sirtuin inhibitor nicotinamide and upon deletion or mutation of its deacetylase domain, indicating a non-catalytic function. Knockdown of Sirt7 led to an increase in HIF-1α and HIF-2α protein levels and an increase in HIF-1 and HIF-2 transcriptional activity. Thus, we identify a novel molecular function of Sirt7 as a negative regulator of HIF signaling.

Data Supplement from Decreased Expression of Cystathionine β-Synthase Promotes Glioma Tumorigenesis

<p>Supplementary Table S1. Primer sequences used for qPCR.</p>

Mersalyl Is a Novel Inducer of Vascular Endothelial Growth Factor Gene Expression and Hypoxia-Inducible Factor 1 Activity

Abstract A3: Collagen hydroxylases are essential for breast cancer metastasis

Abstract Metastasis is the leading cause of death among patients who have breast cancer. Understanding the role of the extracellular matrix in the metastatic process may lead to the development of improved therapies to treat cancer patients. Intratumoral hypoxia, found in the majority of breast cancers, is associated with an increased risk of metastasis and mortality. Here we demonstrate that hypoxia-inducible factor 1 activates the transcription of genes encoding collagen prolyl hydroxylases that are critical for collagen deposition by breast cancer cells. We identify that expression of collagen prolyl hydroxylases promotes cancer cell alignment along collagen fibers resulting in enhanced cancer cell invasion and metastasis to lymph nodes and lungs. We establish the prognostic significance of collagen hydroxylase expression in human breast cancer biopsies and evaluate the novel use of ethyl 3,4-dihydroxybenzoate, a hydroxylase inhibitor, which decreases tumor fibrosis and metastasis in a mouse model of breast cancer. Citation Format: Daniele M. Gilkes, Pallavi Chaturvedi, Carmen Wong, Saumendra Bajpai, Hong Wei, Maimon Hubbi, Denis Wirtz, Gregg Semenza. Collagen hydroxylases are essential for breast cancer metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr A3.

Supplemental Figure 1 from Systemic Delivery of Microencapsulated 3-Bromopyruvate for the Therapy of Pancreatic Cancer

<p>This figure provides an overview of the TEM results.</p>

Increased expression of fractalkine and its receptor in mouse hind limb ischemic tissues and bone marrow-derives stem cells under hypoxic condition

Nitric oxide prevents axonal degeneration by inducing HIF-1–dependent expression of erythropoietin

Nitric oxide (NO) is a signaling molecule that can trigger adaptive (physiological) or maladaptive (pathological) responses to stress stimuli in a context-dependent manner. We have previously reported that NO may signal axonal injury to neighboring glial cells. In this study, we show that mice deficient in neuronal nitric oxide synthase (nNOS −/− ) are more vulnerable than WT mice to toxin-induced peripheral neuropathy. The administration of NO donors to primary dorsal root ganglion cultures prevents axonal degeneration induced by acrylamide in a dose-dependent manner. We demonstrate that NO-induced axonal protection is dependent on hypoxia-inducible factor (HIF)-1–mediated transcription of erythropoietin (EPO) within glial (Schwann) cells present in the cultures. Transduction of Schwann cells with adenovirus AdCA5 encoding a constitutively active form of HIF-1α results in amelioration of acrylamide-induced axonal degeneration in an EPO-dependent manner. Mice that are partially deficient in HIF-1α (HIF-1α +/− ) are also more susceptible than WT littermates to toxic neuropathy. Our results indicate that NO→HIF-1→EPO signaling represents an adaptive mechanism that protects against axonal degeneration.