Search

In the Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS), inhibition of the IL1β inflammatory pathway by canakinumab has been shown to significantly reduce lung cancer incidence and mortality. Here we performed molecular characterization of CANTOS patients who developed lung cancer during the study, including circulating tumor DNA (ctDNA) and soluble inflammatory biomarker analysis. Catalogue of Somatic Mutations in Cancer (COSMIC) database ctDNA mutations were detected in 65% (46/71) of the CANTOS patients with lung cancer, with 51% (36/71) having detectable ctDNA at the time point closest to lung cancer diagnosis and 43% (29/67) having detectable ctDNA at trial randomization. Mutations commonly found in lung cancer were observed with no evidence of enrichment in any mutation following canakinumab treatment. Median time to lung cancer diagnosis in patients with (n = 29) versus without (n = 38) detectable COSMIC ctDNA mutations at baseline was 407 days versus 837 days (P = 0.011). For serum inflammatory biomarker analysis, circulating levels of C-reactive protein (CRP), IL6, IL18, IL1 receptor antagonist, TNFα, leptin, adiponectin, fibrinogen, and plasminogen activator inhibitor-1 were determined. Patients with the highest level of baseline CRP or IL6, both downstream of IL1β signaling, trended toward a shorter time to lung cancer diagnosis. Other inflammation markers outside of the IL1β pathway at baseline did not trend with time to lung cancer diagnosis. These results provide further evidence for the importance of IL1β-mediated protumor inflammation in lung cancer and suggest canakinumab's effect may be mediated in part by delaying disease progression of diverse molecular subtypes of lung cancer.Significance:These findings suggest that targeting the IL1β inflammatory pathway might be critical in reducing tumor-promoting inflammation and lung cancer incidence.

Supplementary Data

In the Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS), inhibition of the IL1β inflammatory pathway by canakinumab has been shown to significantly reduce lung cancer incidence and mortality. Here we performed molecular characterization of CANTOS patients who developed lung cancer during the study, including circulating tumor DNA (ctDNA) and soluble inflammatory biomarker analysis. Catalogue of Somatic Mutations in Cancer (COSMIC) database ctDNA mutations were detected in 65% (46/71) of the CANTOS patients with lung cancer, with 51% (36/71) having detectable ctDNA at the time point closest to lung cancer diagnosis and 43% (29/67) having detectable ctDNA at trial randomization. Mutations commonly found in lung cancer were observed with no evidence of enrichment in any mutation following canakinumab treatment. Median time to lung cancer diagnosis in patients with (n = 29) versus without (n = 38) detectable COSMIC ctDNA mutations at baseline was 407 days versus 837 days (P = 0.011). For serum inflammatory biomarker analysis, circulating levels of C-reactive protein (CRP), IL6, IL18, IL1 receptor antagonist, TNFα, leptin, adiponectin, fibrinogen, and plasminogen activator inhibitor-1 were determined. Patients with the highest level of baseline CRP or IL6, both downstream of IL1β signaling, trended toward a shorter time to lung cancer diagnosis. Other inflammation markers outside of the IL1β pathway at baseline did not trend with time to lung cancer diagnosis. These results provide further evidence for the importance of IL1β-mediated protumor inflammation in lung cancer and suggest canakinumab's effect may be mediated in part by delaying disease progression of diverse molecular subtypes of lung cancer. Significance: These findings suggest that targeting the IL1β inflammatory pathway might be critical in reducing tumor-promoting inflammation and lung cancer incidence.

IMPORTANCE: Clonal hematopoiesis of indeterminate potential (CHIP) is associated with increased risk of atherosclerotic cardiovascular disease, and mouse experiments suggest that CHIP related to Tet2 loss of function in myeloid cells accelerates atherosclerosis via augmented interleukin (IL) 1β signaling. OBJECTIVE: To assess whether individuals with CHIP have greater cardiovascular event reduction in response to IL-1β neutralization in the Canankinumab Anti-inflammatory Thrombosis Outcomes Trial (CANTOS). DESIGN, SETTING, AND PARTICIPANTS: This randomized clinical trial took place from April 2011 to June 2017 at more than 1000 clinical sites in 39 countries. Targeted deep sequencing of genes previously associated with CHIP in a subset of trial participants using genomic DNA prepared from baseline peripheral blood samples were analyzed. All participants had prior myocardial infarction and elevated high-sensitivity C-reactive protein level above 0.20 mg/dL. Analysis took place between June 2017 and December 2021. INTERVENTIONS: Canakinumab, an anti–IL-1β antibody, given at doses of 50, 150, and 300 mg once every 3 months. MAIN OUTCOMES AND MEASURES: Major adverse cardiovascular events (MACE). RESULTS: A total of 338 patients (8.6%) were identified in this subset with evidence for clonal hematopoiesis. As expected, the incidence of CHIP increased with age; the mean (SD) age of patients with CHIP was 66.3 (9.2) years and 61.5 (9.6) years in patients without CHIP. Unlike other populations that were not preselected for elevated C-reactive protein, in the CANTOS population variants in TET2 were more common than DNMT3A (119 variants in 103 patients vs 86 variants in 85 patients). Placebo-treated patients with CHIP showed a nonsignificant increase in the rate of MACE compared with patients without CHIP using a Cox proportional hazard model (hazard ratio, 1.32 [95% CI, 0.86-2.04]; P = .21). Exploratory analyses of placebo-treated patients with a somatic variant in either TET2 or DNMT3A (n = 58) showed an equivocal risk for MACE (hazard ratio, 1.65 [95% CI, 0.97-2.80]; P = .06). Patients with CHIP due to somatic variants in TET2 also had reduced risk for MACE while taking canakinumab (hazard ratio, 0.38 [95% CI, 0.15-0.96]) with equivocal difference compared with others (P for interaction = .14). CONCLUSIONS AND RELEVANCE: These results are consistent with observations of increased risk for cardiovascular events in patients with CHIP and raise the possibility that those with TET2 variants may respond better to canakinumab than those without CHIP. Future studies are required to further substantiate this hypothesis. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01327846

No formal abstract in format we plan to submit to journal (a short report). Informally, the work presented here adds to a body of evidence that shows how polygenic risk scores (PRS) for coronary artery disease (CAD) can be used to inform on patient's disease severity, disease progression, and potential for treatment response stratification. Key results include, patients in highest tertile PRS have a higher CAD disease burden at baseline (measured by number of myocardial infractions at trail start), progress faster in CAD (measured by time to first major adverse cardiovascular event, MACE), and may respond better to Canakinumab therapy at the highest dose of 300mg.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting over 33 million individuals throughout the world. AF is highly heritable and recent genome-wide association studies (GWAS) have cumulatively identified over 100 loci associated with AF risk. Genome-wide association studies (GWAS) often identify transcription factor (TF) loci in association with complex human diseases, implying that a significant transcriptional component underlies human disease risk and etiology. The transcription factors ZFPM2 (FOG2), GATA4, and TBX5 have all been implicated in human AF risk by genetic studies. We hypothesized that FOG2, GATA4, and TBX5 functionally interact to regulate a gene regulatory network essential for atrial rhythm control. We generated a novel mouse model of spontaneous AF based on FOG2 overexpression. FOG2 ChIP-seq identified FOG2 genomic localization at loci co-occupied by GATA4, a known FOG2 binding partner. However, we found that FOG2 OE caused gene expression alterations that correlated more highly with TBX5-dependent rather than GATA4-dependent gene expression, including a module of calcium handling genes required for atrial rhythm homeostasis. We applied TF-dependent non-coding transcriptional profiling to examine the FOG2 dependent atrial GRN, which identified 805 candidate regulatory regions with accessible chromatin and FOG2 dependent ncRNAs. TBX5 removal and FOG2 OE caused highly correlated dysregulation of ncRNA expression at open chromatin regions genome-wide, suggesting a functional interaction between TBX5 and FOG2. Furthermore, FOG2 OE only affected enhancer activity by altered ncRNA abundance at locations of TBX5 co-binding. The shared TBX5/FOG2 genomic interaction predicted a potential genetic interaction, and we found that cardiac rhythm abnormalities caused by Tbx5 haploinsufficiency were rescued by Fog2 haploinsufficiency. Taken together, TF-dependent ncRNA-profiling revealed an interconnected cardiac rhythm gene regulatory network (GRN) between FOG2, TBX5 and GATA4. These data nominate a specific model in which FOG2 is recruited by GATA4 to modulate a co-bound TBX5-dependent atrial gene regulatory network for calcium handling and atrial rhythm homeostasis.

Ets1 is emerging as a key transcription factor that is required to prevent autoimmunity in mice and humans. Ets1 is expressed in both B and T cells, and mice lacking Ets1 are characterized by excess B and T cell activation, leading to enhanced formation of Ab-secreting cells and high titers of autoantibodies. In humans, genome-wide association studies have detected associations of single nucleotide polymorphisms in the human ETS1 gene with autoimmune diseases, including lupus. An increased fraction of CD4+ T cells from Ets1−/− mice have an activated effector-memory phenotype, and there are aberrations in differentiation that contribute to the autoimmune phenotype. In vitro studies of B cells suggest that Ets1 may have B cell–intrinsic effects as well. To confirm B cell–intrinsic roles for Ets1, we crossed CD19-Cre mice to mice with a floxed allele of Ets1. Mice with a B cell–specific deletion of Ets1 show increases in B cell activation, numbers of Ab-secreting cells, and levels of autoantibodies, despite the fact that T cells are normal. However, when compared with conventional Ets1 knockout mice, mice with B cell–specific loss of Ets1 have a significantly milder phenotype. These results demonstrate that Ets1 is required in B cells to prevent autoimmune responses but that loss of Ets1 activity in other cell types is required for maximal autoimmune phenotypes.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Recent work has implicated numerous transcription factors in AF risk, including ZFPM2 (FOG2), GATA4, and TBX5. FOG2 is overexpressed in human heart failure, a major AF risk factor. We found that genetic inducible physiologic overexpression of FOG2 in the adult mouse heart caused spontaneous atrial fibrillation. Single cell electrophysiology revealed action potential prolongation and inappropriate depolarizations in FOG2-OE atrial cardiomyocytes. RNA-seq of the FOG2-OE left atrium prior to AF onset demonstrated that FOG2 suppresses a network of calcium cycling genes, providing a possible mechanism for disrupted cardiomyocyte electrophysiology. FOG2 ChIP-seq demonstrated genomic localization only at locations co-occupied by GATA4. Unexpectedly, we observed little overlap between genes activated by GATA4 and repressed by FOG2. Instead, we observed highly significant overlap between genes repressed by FOG2 and activated by TBX5. To identify the FOG2-dependent atrial gene regulatory network, we performed differential deep sequencing of ncRNAs. Comparison of atrial FOG2-dependent non-coding transcripts with previously performed TBX5-dependent ncRNA profiling indicated that TBX5 activated and FOG2 repressed a shared atrial rhythm gene regulatory network. Integration of FOG2, GATA4, and TBX5 ChIP-seq revealed that FOG2 only affected ncRNA transcription, indicative of enhancer activity changes, at locations co-occupied by TBX5. TBX5-dependent activation of specific regulatory elements for calcium handling genes was abolished by FOG2 in vitro . The genomic TBX5/FOG2 interaction predicted a genetic interaction in-vivo , in which cardiac conduction and arrhythmia abnormalities caused by Tbx5 haploinsufficiency were rescued by FOG2 haploinsufficiency. Non-coding RNA profiling thereby predicted a novel functional TF interaction between FOG2 and TBX5. This work reveals a specific genomic model of atrial rhythm control in which FOG2 is recruited to GATA4 and TBX5 bound locations to modulate a TBX5-dependent atrial gene regulatory network for calcium handling and cardiac rhythm homeostasis.

ObjectivesWnt signalling has been implicated in activating a fibrogenic programme in fibroblasts in systemic sclerosis (SSc). Porcupine is an O-acyltransferase required for secretion of Wnt proteins in mammals. Here, we aimed to evaluate the antifibrotic effects of pharmacological inhibition of porcupine in preclinical models of SSc.MethodsThe porcupine inhibitor GNF6231 was evaluated in the mouse models of bleomycin-induced skin fibrosis, in tight-skin-1 mice, in murine sclerodermatous chronic-graft-versus-host disease (cGvHD) and in fibrosis induced by a constitutively active transforming growth factor-β-receptor I.ResultsTreatment with pharmacologically relevant and well-tolerated doses of GNF6231 inhibited the activation of Wnt signalling in fibrotic murine skin. GNF6231 ameliorated skin fibrosis in all four models. Treatment with GNF6231 also reduced pulmonary fibrosis associated with murine cGvHD. Most importantly, GNF6231 prevented progression of fibrosis and showed evidence of reversal of established fibrosis.ConclusionsThese data suggest that targeting the Wnt pathway through inhibition of porcupine provides a potential therapeutic approach to fibrosis in SSc. This is of particular interest, as a close analogue of GNF6231 has already demonstrated robust pathway inhibition in humans and could be available for clinical trials.

Background Evidence suggests that interleukin (IL)-1β is important in the pathogenesis of atherosclerosis and its complications and that inhibiting IL-1β may favorably affect vascular disease progression. Objectives The goal of this study was to evaluate the effects of IL-1β inhibition with canakinumab versus placebo on arterial structure and function, determined by magnetic resonance imaging. Methods Patients (N = 189) with atherosclerotic disease and either type 2 diabetes mellitus or impaired glucose tolerance were randomized to receive placebo (n = 94) or canakinumab 150 mg monthly (n = 95) for 12 months. They underwent magnetic resonance imaging of the carotid arteries and aorta. Results There were no statistically significant differences between canakinumab compared with placebo in the primary efficacy and safety endpoints. There was no statistically significant change in mean carotid wall area and no effect on aortic distensibility, measured at 3 separate anatomic sites. The change in mean carotid artery wall area was –3.37 mm2 after 12 months with canakinumab versus placebo. High-sensitivity C-reactive protein was significantly reduced by canakinumab compared with placebo at 3 months (geometric mean ratio [GMR]: 0.568; 95% confidence interval [CI]: 0.436 to 0.740; p < 0.0001) and 12 months (GMR: 0.56; 95% CI: 0.414 to 0.758; p = 0.0002). Lipoprotein(a) levels were reduced by canakinumab compared with placebo (–4.30 mg/dl [range: –8.5 to –0.55 mg/dl]; p = 0.025] at 12 months), but triglyceride levels increased (GMR: 1.20; 95% CI: 1.046 to 1.380; p = 0.01). In these patients with type 2 diabetes mellitus or impaired glucose tolerance, canakinumab had no effect compared with placebo on any of the measures assessed by using a standard oral glucose tolerance test. Conclusions There were no statistically significant effects of canakinumab on measures of vascular structure or function. Canakinumab reduced markers of inflammation (high-sensitivity C-reactive protein and interleukin-6), and there were modest increases in levels of total cholesterol and triglycerides. (Safety & Effectiveness on Vascular Structure and Function of ACZ885 in Atherosclerosis and Either T2DM or IGT Patients; NCT00995930)

FOG-2 is a multi-zinc finger protein that binds the transcriptional activator GATA4 and modulates GATA4-mediated regulation of target genes during heart development. Our previous work has demonstrated that the Nucleosome Remodeling and Deacetylase (NuRD) complex physically interacts with FOG-2 and is necessary for FOG-2 mediated repression of GATA4 activity in vitro. However, the relevance of this interaction for FOG-2 function in vivo has remained unclear. In this report, we demonstrate the importance of FOG-2/NuRD interaction through the generation and characterization of mice homozygous for a mutation in FOG-2 that disrupts NuRD binding (FOG-2(R3K5A)). These mice exhibit a perinatal lethality and have multiple cardiac malformations, including ventricular and atrial septal defects and a thin ventricular myocardium. To investigate the etiology of the thin myocardium, we measured the rate of cardiomyocyte proliferation in wild-type and FOG-2(R3K5A) developing hearts. We found cardiomyocyte proliferation was reduced by 31±8% in FOG-2(R3K5A) mice. Gene expression analysis indicated that the cell cycle inhibitor Cdkn1a (p21(cip1)) is up-regulated 2.0±0.2-fold in FOG-2(R3K5A) hearts. In addition, we demonstrate that FOG-2 can directly repress the activity of the Cdkn1a gene promoter, suggesting a model by which FOG-2/NuRD promotes ventricular wall thickening by repression of this cell cycle inhibitor. Consistent with this notion, the genetic ablation of Cdkn1a in FOG-2(R3K5A) mice leads to an improvement in left ventricular function and a partial rescue of left ventricular wall thickness. Taken together, our results define a novel mechanism in which FOG-2/NuRD interaction is required for cardiomyocyte proliferation by directly down-regulating the cell cycle inhibitor Cdkn1a during heart development.

BACKGROUND Developmental abnormalities of the abdominal aorta are exceedingly rare, and the molecular mechanisms underlying these defects are unknown. CASE We present computed angiographic findings of a 64-year-old female with long-standing hypertension having an abdominal double aorta accompanied by a double inferior vena cava. The abdominal aorta bifurcated into two lumens just caudal to the diaphragm at the level of the 12th thoracic vertebra. The dorsal abdominal aortic trunk supplied several lumbar arteries, the inferior mesenteric artery, and both iliac arteries. The ventral abdominal aortic trunk supplied the celiac artery, both renal arteries, and the superior mesenteric artery. CONCLUSION We propose that a defect in the development of the aortic vascular smooth muscle is a possible mechanism for this rare anomaly based on our current understanding of the formation of the aorta during early embryonic development. Birth Defects Research (Part A), 2011. © 2011 Wiley-Liss, Inc.

Cardiac failure is associated with diminished activation of the transcription factor cyclic nucleotide regulatory element binding-protein (CREB), and heart-specific expression of a phosphorylation-deficient CREB mutant in transgenic mice [dominant negative CREB (dnCREB) mice] recapitulates the contractile phenotypes of cardiac failure (Fentzke RC, Korcarz CE, Lang RM, Lin H, Leiden JM. Dilated cardiomyopathy in transgenic mice expressing a dominant-negative CREB transcription factor in the heart. J Clin Invest 101: 2415–2426, 1998). In the present study, we demonstrated significantly elevated mortality and contractile dysfunction in female compared with male dnCREB mice. Female dnCREB mice demonstrated a 21-wk survival of only 17% compared with 67% in males ( P < 0.05) and exclusively manifest decreased cardiac peroxisome proliferator-activated receptor-γ coactivator-1α and estrogen-related receptor-α content, suggesting sex-related effects on cardiac mitochondrial function. Hearts from 4-wk-old dnCREB mice of both sexes demonstrated diminished mitochondrial respiratory capacity compared with nontransgenic controls. However, by 12 wk of age, there was a significant decrease in mitochondrial density (citrate synthase activity) and deterioration of mitochondrial structure, as demonstrated by transmission electron microscopy, in female dnCREB mice, which were not found in male transgenic littermates. Subsarcolemmal mitochondria isolated from hearts of female, but not male, dnCREB mice demonstrated increased ROS accompanied by decreases in the expression/activity of the mitochondrial antioxidants MnSOD and glutathione peroxidase. These results demonstrate that heart-specific dnCREB expression results in mitochondrial respiratory dysfunction in both sexes; however, increased oxidant burden, reduced antioxidant expression, and disrupted mitochondrial structure are exacerbated by the female sex, preceding and contributing to the greater contractile morbidity and mortality. These results provide further support for the role of the CREB transcription factor in regulating mitochondrial integrity and identify a critical pathway that may contribute to sex differences in heart failure.

Defects in cardiac neural crest lead to congenital heart disease through failure of cardiac outflow tract and ventricular septation. In this report, we demonstrate a previously unappreciated role for the transcription factor Ets1 in the regulation of cardiac neural crest development. When bred onto a C57BL/6 genetic background, Ets1−/− mice have a nearly complete perinatal lethality. Histologic examination of Ets1−/− embryos revealed a membranous ventricular septal defect and an abnormal nodule of cartilage within the heart. Lineage-tracing experiments in Ets1−/− mice demonstrated that cells of the neural crest lineage form this cartilage nodule and do not complete their migration to the proximal aspects of the outflow tract endocardial cushions, resulting in the failure of membranous interventricular septum formation. Given previous studies demonstrating that the MEK/ERK pathway directly regulates Ets1 activity, we cultured embryonic hearts in the presence of the MEK inhibitor U0126 and found that U0126 induced intra-cardiac cartilage formation, suggesting the involvement of a MEK/ERK/Ets1 pathway in blocking chondrocyte differentiation of cardiac neural crest. Taken together, these results demonstrate that Ets1 is required to direct the proper migration and differentiation of cardiac neural crest in the formation of the interventricular septum, and therefore could play a role in the etiology of human congenital heart disease.

The transcriptional co‐factor Friend of GATA1 (FOG‐1) has been shown to interact with subunits of the nucleosome remodelling and histone deacetylase (NuRD) complex through a specific motif located at its N‐terminus. To test the importance of FOG‐1/NuRD interaction for haematopoiesis in vivo , we generated mice with a mutation that specifically disrupts FOG‐1/NuRD interaction (FOG‐1 R3K5A ). Homozygous FOG‐1 R3K5A mice were found to have splenomegaly, extramedullary erythropoiesis, granulocytosis and thrombocytopaenia secondary to a block in megakaryocyte maturation. FOG‐1 R3K5A/R3K5A megakaryocytes and erythroid progenitors expressed increased levels of GATA2, showing that FOG‐1/NuRD interaction is required for the earlier described ‘GATA Switch’. In addition, ablation of FOG‐1/NuRD interaction led to inappropriate expression of mast cell and eosinophil‐specific genes in the megakaryocyte and erythroid lineages. Chromatin immunoprecipitation experiments revealed that the NuRD complex was not properly recruited to a mast cell gene promoter in FOG‐1 R3K5A/R3K5A megakaryocytes, suggesting that FOG‐1/NuRD interaction is required for the direct suppression of mast cell gene expression. Taken together, these results underscore the importance of the FOG‐1/NuRD interaction for the re‐enforcement of lineage commitment during erythropoiesis and megakaryopoiesis in vivo .

Zook et al. use a novel mouse model to demonstrate a requirement for the transcription factor ETS1 in the development and function of group 2 innate lymphoid cells., Group 2 innate lymphoid cells (ILC2s) are a subset of ILCs that play a protective role in the response to helminth infection, but they also contribute to allergic lung inflammation. Here, we report that the deletion of the ETS1 transcription factor in lymphoid cells resulted in a loss of ILC2s in the bone marrow and lymph nodes and that ETS1 promotes the fitness of the common progenitor of all ILCs. ETS1-deficient ILC2 progenitors failed to up-regulate messenger RNA for the E protein transcription factor inhibitor ID2, a critical factor for ILCs, and these cells were unable to expand in cytokine-driven in vitro cultures. In vivo, ETS1 was required for the IL-33–induced accumulation of lung ILC2s and for the production of the T helper type 2 cytokines IL-5 and IL-13. IL-25 also failed to elicit an expansion of inflammatory ILC2s when these cells lacked ETS1. Our data reveal ETS1 as a critical regulator of ILC2 expansion and cytokine production and implicate ETS1 in the regulation of Id2 at the inception of ILC2 development.

The FOG family of transcriptional co-factors is composed of two members in mammals: FOG-1 and FOG-2. Both have been shown to bind to GATA factors and function as transcriptional co-repressors in specific cell and promoter contexts. We have previously defined a novel repression domain localized to the N-terminus of each FOG family member, the FOG Repression Motif, which is necessary for FOG-mediated transcriptional repression. In this report, we describe the identification and characterization of a novel isoform of FOG-2 lacking the FOG Repression Motif. In contrast to full-length FOG-2, this isoform is expressed predominately in the embryonic and adult heart. It can bind GATA4 avidly, but is unable to repress GATA4-mediated activation of cardiac-restricted gene promoters. Together, these results suggest that FOG-2 repressive activity may be modulated by the generation of isoforms of FOG-2 lacking the FOG repression motif.

To further our understanding of FOG gene function during cardiac development, we utilized zebrafish to examine FOG's role in the early steps of heart morphogenesis. We identified fragments of three fog genes in the zebrafish genomic database and isolated full-length coding sequences for each of these genes by using a combination of RT-PCR and 5′-RACE. One gene was similar to murine FOG-1 ( fog1 ), while the remaining two were similar to murine FOG-2 ( fog2a and fog2b ). All Fog proteins were able to physically interact with GATA4 and function as transcriptional co-repressors. Whole-mount in situ hybridization revealed fog1 expression in the heart, the hematopoietic system, and the brain, while fog2a and fog2b expression was restricted to the brain. Injection of zebrafish embryos with a morpholino directed against fog1 resulted in embryos with a large pericardial effusion and an unlooped heart tube. This looping defect could be rescued by co-injection of mRNA encoding murine FOG-1, but not by mRNA encoding FOG-1 lacking the FOG repression motif. Taken together, these results demonstrate the importance of FOG proteins for zebrafish cardiac development and suggest a previously unappreciated role for FOG proteins in heart looping that is dependent on the FOG repression motif.

Members of the Friend of GATA (FOG) family of transcriptional co-factors are required for the development of both the cardiovascular and hematopoietic systems. FOG proteins physically interact with members of the GATA family of transcriptional activators and modulate their activity. We have previously shown that FOG-2 can bind to the N-terminal zinc finger of GATA4 and, via this interaction, repress GATA4-mediated transcriptional activation of various cardiac promoters. In this report we further characterize the domain of FOG-2 necessary for repression of GATA4 transcriptional activity. We show that FOG-2-mediated repression is not blocked by the histone deacetylase inhibitor tricostatin A, suggesting that FOG-2 repression of GATA4 occurs via a histone deacetylase independent mechanism. N-terminal deletion mutants of FOG-2 revealed that the first 12 amino acids of FOG-2 are necessary for FOG-2-mediated repression. Fusion of these 12 amino acids to the DNA binding domain of GAL4 demonstrated that this region is sufficient to mediate transcriptional repression even when recruited to a heterologous promoter. Single amino acid substitutions within this N-terminal domain of FOG-2 defined the critical amino acid sequence as RRKQxxPxxI. Interestingly, a search of the NCBI protein data base identified several other partially characterized zinc finger transcriptional repressors from various vertebrate species that contained this motif at their N terminus. Taken together, these observations define a novel transcriptional repression motif and a superfamily of zinc finger transcriptional repressors.

GATA4 is a transcriptional activator of cardiac-restricted promoters and is required for normal cardiac morphogenesis. Friend of GATA-2 (FOG-2) is a multizinc finger protein that associates with GATA4 and represses GATA4-dependent transcription. To better understand the transcriptional repressor activity of FOG-2 we performed a functional analysis of the FOG-2 protein. The results demonstrated that 1) zinc fingers 1 and 6 of FOG-2 are each capable of interacting with evolutionarily conserved motifs within the N-terminal zinc finger of mammalian GATA proteins, 2) a nuclear localization signal (RKRRK) (amino acids 736-740) is required to program nuclear targeting of FOG-2, and 3) FOG-2 can interact with the transcriptional co-repressor, C-terminal-binding protein-2 via a conserved sequence motif in FOG-2 (PIDLS). Surprisingly, however, this interaction with C-terminal-binding protein-2 is not required for FOG-2-mediated repression of GATA4-dependent transcription. Instead, we have identified a novel N-terminal domain of FOG-2 (amino acids 1-247) that is both necessary and sufficient to repress GATA4-dependent transcription. This N-terminal repressor domain is functionally conserved in the related protein, Friend of GATA1. Taken together, these results define a set of evolutionarily conserved mechanisms by which FOG proteins repress GATA-dependent transcription and thereby form the foundation for genetic studies designed to elucidate the role of FOG-2 in cardiac development.

Erythropoietin (Epo)-responsive anemia is a debilitating complication of chronic renal failure and human immunodeficiency virus (HIV) infection that effects more than 150,000 Americans. Patients with Epo-responsive anemias are currently treated with repeated injections of recombinant human Epo. In the studies described in this report, we have examined the safety and efficacy of using a single intramuscular (i.m.) injection of replication-defective adenoviral vectors (RDAd) encoding Epo for the treatment of Epo-responsive anemias in both mice and non-human primates. Our results demonstrate that there is a threshold dose of virus (2.5-8 x 10(7) pfu/gram of body weight) which is required to obtain long-term Epo expression and polycythemia in both species. A single i.m. injection of mice with 10(9) pfu of an RDAd encoding murine Epo (AdmEpo) resulted in elevations in hematocrits from control values of 49 +/- 0.9% to treated values of 81 +/- 3%, which were stable for more than 1 year. Similarly, a single i.m. injection of a monkey with 4 x 10(11) pfu of an RDAd-encoding simian Epo (AdsEpo) resulted in elevations of hematocrits from control levels of 40% to treated levels of > or =70%, which were stable for 84 days. Intramuscular injection of monkeys with AdsEpo appeared to be safe in that we did not detect abnormalities in chest X-rays, serum chemistries, hematologic, or clotting profiles (apart from elevated hematocrits) or organ histologies during the 84-day time course of the experiment. Taken together, these results suggest the feasibility of using i.m. injection of RDAd for the treatment of Epo-responsive anemias in humans.

The past five years have witnessed tremendous growth in the field of gene therapy, with pre-clinical and clinical gene therapy trials for diseases as diverse as cancer, AIDS and atherosclerosis. These studies have utilized many different vectors and target organs in order to achieve therapeutic effects. In this review, we examine the rationale for using skeletal muscle as a target tissue for gene therapy, discuss the wide array of vectors that have been used for muscle-based gene therapy, summarize the disease-targets that have been approached using these techniques, and discuss some of the obstacles that remain to be overcome en route to successful muscle-based human gene therapy.

The mechanistic links between exposure to airborne particulate matter (PM) pollution and the associated increases in cardiovascular morbidity and mortality, particularly in people with congestive heart failure (CHF), have not been identified. To advance understanding of this issue, genetically engineered mice (CREB(A133)) exhibiting severe dilated cardiomyopathic changes were exposed to ambient PM collected in Baltimore. CREB(A133) mice, which display aberrant cardiac physiology and anatomy reminiscent of human CHF, displayed evidence of basal autonomic aberrancies (compared with wild-type mice) with PM exposure via aspiration, producing significantly reduced heart rate variability, respiratory dysynchrony, and increased ventricular arrhythmias. Carotid body afferent nerve responses to hypoxia and hyperoxia-induced respiratory depression were pronounced in PM-challenged CREB(A133) mice, and denervation of the carotid bodies significantly reduced PM-mediated cardiac arrhythmias. Genome-wide expression analyses of CREB(A133) left ventricular tissues demonstrated prominent Na(+) and K(+) channel pathway gene dysregulation. Subsequent PM challenge increased tyrosine phosphorylation and nitration of the voltage-gated type V cardiac muscle α-subunit of the Na(+) channel encoded by SCN5A. Ranolazine, a Na(+) channel modulator that reduces late cardiac Na(+) channel currents, attenuated PM-mediated cardiac arrhythmias and shortened PM-elongated QT intervals in vivo. These observations provide mechanistic insights into the epidemiologic findings in susceptibility of human CHF populations to PM exposure. Our results suggest a multiorgan pathobiology inherent to the CHF phenotype that is exaggerated by PM exposure via heightened carotid body sensitivity and cardiac Na(+) channel dysfunction.

See related article, pages 1818–1828 Cardiac development is an intricate process involving the migration and assembly of multiple cell types from distinct lineages to form a mature heart. Cells of the proepicardium define one such lineage and have been receiving increasing attention given their role in the formation of the epicardium, and the central role of epicardium as a signaling center during heart development and repair.1,2 The proepicardium is a mesothelial structure in the wall of the pericardial cavity just dorsal to the developing heart tube that has a “cluster of grapes”–like appearance. It has been identified in human, mouse, chick, and most recently in zebrafish embryos.3,4 The transcription factors Tbx18 (T-box factor 18), Wt-1 (Wilms tumor 1), and Tcf21 (transcription factor 21) (also known as epicardin or capsulin) are highly expressed in the proepicardium and serve as molecular markers of this structure, although none of these factors is expressed exclusively in the proepicardium. Cells of the proepicardium migrate onto the developing heart tube and completely cover it in an epithelial layer, the epicardium. Epicardial cells then undergo an epithelial-to-mesenchymal transition and invade into the underlying myocardium to become fibroblasts and cells of the coronary vasculature. There are several examples of mutations in mice that disrupt epicardial development.1 The failure to form the epicardium leads to a reduction in cardiomyocyte proliferation, a disruption in cardiac morphogenesis, and embryonic lethality attributable to heart failure. Although the importance of the proepicardium for heart development is clear, we are just beginning …

Ferlin proteins mediate membrane-fusion events in response to Ca2+. Myoferlin, a member of the ferlin family, is required for normal muscle development, during which it mediates myoblast fusion. We isolated both damaged and intact myofibers from a mouse model of muscular dystrophy using laser-capture microdissection and found that the levels of myoferlin mRNA and protein were increased in damaged myofibers. To better define the components of the muscle-injury response, we identified a discreet 1543-bp fragment of the myoferlin promoter, containing multiple NFAT-binding sites, and found that this was sufficient to drive high-level myoferlin expression in cells and in vivo. This promoter recapitulated normal myoferlin expression in that it was downregulated in healthy myofibers and was upregulated in response to myofiber damage. Transgenic mice expressing GFP under the control of the myoferlin promoter were generated and GFP expression in this model was used to track muscle damage in vivo after muscle injury and in muscle disease. Myoferlin modulates the response to muscle injury through its activity in both myoblasts and mature myofibers.

Background— Excessive proliferation and impaired apoptosis of pulmonary artery (PA) smooth muscle cells (PASMCs) contribute to vascular obstruction in patients and fawn-hooded rats (FHRs) with PA hypertension (PAH). Expression and activity of mitochondrial superoxide dismutase-2 (SOD2), the major generator of H 2 O 2 , is known to be reduced in PAH; however, the mechanism and therapeutic relevance of this are unknown. Methods and Results— SOD2 expression in PASMCs is decreased in PAH patients and FHRs with PAH. FHR PASMCs have higher proliferation and lower apoptosis rates than Sprague-Dawley rat PASMCs. Moreover, FHR PASMCs have hyperpolarized mitochondria, low H 2 O 2 production, and reduced cytoplasmic and mitochondrial redox state. Administration of SOD2 small interfering RNA to normal PASMCs recapitulates the FHR PAH phenotype, hyperpolarizing mitochondria, decreasing H 2 O 2 , and inhibiting caspase activity. Conversely, SOD2 overexpression in FHR PASMCs or therapy with the SOD-mimetic metalloporphyrin Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP) reverses the hyperproliferative PAH phenotype. Importantly, SOD-mimetic therapy regresses PAH in vivo. Investigation of the SOD2 gene revealed no mutation, suggesting a possible epigenetic dysregulation. Genomic bisulfite sequencing demonstrates selective hypermethylation of a CpG island in an enhancer region of intron 2 and another in the promoter. Differential methylation occurs selectively in PAs versus aortic SMCs and is reversed by the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine, restoring both SOD2 expression and the ratio of proliferation to apoptosis. Expression of the enzymes that mediate gene methylation, DNA methyltransferases 1 and 3B, is upregulated in FHR lungs. Conclusions— Tissue-specific, epigenetic SOD2 deficiency initiates and sustains a heritable form of PAH by impairing redox signaling and creating a proliferative, apoptosis-resistant PASMC. SOD augmentation regresses experimental PAH. The discovery of an epigenetic component to PAH may offer new therapeutic targets.

Abstract : The establishment of the coronary circulation is critical for the development of the embryonic heart. Over the last several years, there has been tremendous progress in elucidating the pathways that control coronary development. Interestingly, many of the pathways that regulate the development of the coronary vasculature are distinct from those governing vasculogenesis in the rest of the embryo. It is becoming increasingly clear that coronary development depends on a complex communication between the epicardium, the subepicardial mesenchyme, and the myocardium mediated in part by secreted growth factors. This communication coordinates the growth of the myocardium with the formation of the coronary vasculature. This review summarizes our present understanding of the role of these growth factors in the regulation of coronary development. Continued progress in this field holds the potential to lead to novel therapeutics for the treatment of patients with coronary artery disease.

Alteration in cell surface carbohydrates, and in particular cell surface sialylation, have been known to occur during oncogenic transformation. To examine the basis for such changes, we have transformed the rat fibroblast cell line FR3T3 with the oncogenes c-Ha-ras EJ, v-mycOK10, v-src, polyoma virus middle T or the transforming bovine papilloma virus 1 (BPV1), and measured the sialytransferase activities of cellular lysates. We found that, in contrast to all other oncogenes examined, c-Ha-ras induced a striking increase in beta-galactoside alpha-2,6-sialytransferase (Gal alpha-2,6-ST) activity in FR3T3 cells. This increase in Gal alpha-2,6-ST activity resulted in the increased expression of cell surface alpha-2,6-linked sialic acid on cell surface glycoconjugates, as determined by cell staining with fluorescein-labelled Sambucus nigra agglutinin. Immunoprecipitation and immunofluorescence experiments revealed that the increase in Gal alpha-2,6-ST activity was due to an elevation of expression of the enzyme. Moreover, Northern analysis suggested that the increased expression of this enzyme was the result of an increase in the steady-state mRNA level of the Gal alpha-2,6-ST gene. These results support the notion that alterations seen in cell surface glycoconjugates during oncogenic transformation can be the result of altered expression of glycosyltransferases.

GATA5 is a member of the GATA zinc finger transcription factor family involved in tissue-specific transcriptional regulation during cell differentiation and embryogenesis. Previous reports indicate that null mutation of the zebrafish GATA5 gene results in embryonic lethality, whereas deletion of exon 1 from the mouse GATA5 gene causes only derangement of female urogenital development. Here, we have identified an alternate promoter within intron 1 of the mouse GATA5 gene that transcribes a 2.5-kb mRNA that lacks exon 1 entirely but includes 82 bp from intron 1 and all of exons 2–6. The alternative promoter was active during transient transfection in cultured airway myocytes and bronchial epithelial cells, and it drove reporter gene expression in gastric epithelial cells in transgenic mice. The 2.5-kb alternative transcript encodes an NH2-terminally truncated “short GATA5” comprising aa 226–404 with a single zinc finger, which retains ability to transactivate the atrial natriuretic factor promoter (albeit less efficiently than full-length GATA5). Another new GATA5 transcript contains all of exons 1–5 and the 5′ portion of exon 6 but lacks the terminal 1143 bp of the 3′-untranslated region from exon 6. These findings extend current understanding of the tissue distribution of GATA5 expression and suggests that GATA5 expression and function are more complex than previously appreciated.

MicroRNAs are increasingly being recognized as regulators of embryonic development; however, relatively few microRNAs have been identified to regulate cardiac development. FOG-2 (also known as zfpm2) is a transcriptional co-factor that we have previously shown is critical for cardiac development. In this report, we demonstrate that FOG-2 expression is controlled at the translational level by microRNA-130a. We identified a conserved region in the FOG-2 3′ untranslated region predicted to be a target for miR-130a. To test the functional significance of this site, we generated an expression construct containing the luciferase coding region fused with the 3′ untranslated region of FOG-2 or a mutant version lacking this microRNA binding site. When these constructs were transfected into NIH 3T3 fibroblasts (which are known to express miR-130a), we observed a 3.3-fold increase in translational efficiency when the microRNA target site was disrupted. Moreover, knockdown of miR-130a in fibroblasts resulted in a 3.6-fold increase in translational efficiency. We also demonstrate that cardiomyocytes express miR-130a and can attenuate translation of mRNAs with a FOG-2 3′ untranslated region. Finally, we generated transgenic mice with cardiomyocyte over-expression of miR-130a. In the hearts of these mice, FOG-2 protein levels were reduced by as much as 80%. Histological analysis of transgenic embryos revealed ventricular wall hypoplasia and ventricular septal defects, similar to that seen in FOG-2 deficient hearts. These results demonstrate the importance of miR-130a for the regulation of FOG-2 protein expression and suggest that miR-130a may also play a role in the regulation of cardiac development.

See related articles, pages 388–397 A vexing problem for clinicians in the management of children and adults with congenital heart disease is the management of the accompanying arrhythmias. In the recent decade, the mutational spectrum associated with human congenital heart disease has begun to come into focus.1 The number of distinct genes implicated in human congenital heart disease is considerable, and a large portion of mutated genes encode transcription factors. Autosomal dominant mutations in NKX2.5 associate with primarily atrial septal defects, but importantly these defects are distinguished by the presence of atrioventricular nodal defects including heart block. The Holt–Oram syndrome, or heart–hand syndrome, arises from dominant mutations in Tbx5, a member of the brachyury family of transcription factors and is also associated with the development of atrioventricular nodal disease. Further investigation of these genes using mouse genetic models has begun to refine the detailed program required for development of specific components of the cardiac conduction system. The mammalian cardiac conduction system is composed of the sinoatrial (SA) node, the atrioventricular node, the His bundle, the left and right bundle branches, and the ventricular Purkinje fibers. For many of these components, transcriptional regulators have been identified that are critical for their proper development or maintenance (see Figure). Nkx2.5 is required for the development and maintenance of the atrioventricular node.2 In addition, the development of the atrioventicular node is also dependent on Tbx5 and Id2, whereas the distal ventricular conduction system requires Id2 and HOP.3,4 The precise delineation and maintenance of the conduction system likely requires more than just these factors. Figure. Transcription factors required for cardiac conduction system development. Top, Schematic of the conduction system of the mammalian heart including the sinus node (blue), atrioventricular node (green), bundle of His (light blue), bundle branches, and Purkinje fibers …

Reduced expression of sarcoplasmic reticulum calcium ATPase (SERCA)2 and other genes in the adult cardiac gene program has raised consideration of an impaired responsiveness to thyroid hormone (T3) that develops in the advanced failing heart. Here, we show that human and murine cardiomyopathy hearts have increased expression of friend of GATA (FOG)-2, a cardiac nuclear hormone receptor corepressor protein. Cardiac-specific overexpression of FOG-2 in transgenic mice led to depressed cardiac function, activation of the fetal gene program, congestive heart failure, and early death. SERCA2 transcript and protein levels were reduced in FOG-2 transgenic hearts, and FOG-2 overexpression impaired T3-mediated SERCA2 expression in cultured cardiomyocytes. FOG-2 physically interacts with thyroid hormone receptor-α1 and abrogated even high levels of T3-mediated SERCA2 promoter activity. These results demonstrate that SERCA2 is an important target of FOG-2 and that increased FOG-2 expression may contribute to a decline in cardiac function in end-stage heart failure by impaired T3 signaling.

FOG-2 is a transcriptional co-regulator that is required for cardiac morphogenesis as mice deficient in this factor die during mid-gestation of cardiac malformations. FOG-2 interacts with GATA4 to attenuate GATA4-dependent gene expression. The first 12 amino acids of FOG-2 (the FOG Repression Motif) are necessary to mediate this repression. To determine the mechanism by which the FOG Repression Motif functions, we identified 7 polypeptides from rat cardiac nuclear extracts that co-purified with a GST-FOG-2 fusion protein. All proteins identified are members of the NuRD nucleosome remodeling complex. Using in vitro binding and co-immunoprecipitation assays, we demonstrate that Metastasis-Associated proteins (MTA)-1, 2 and 3 and Retinoblastoma binding proteins RbAp46 and RbAp48 interact with FOG-2, but not with a mutant form of FOG-2 that is unable to repress transcription. Furthermore, we define a novel domain located in the C-terminal portion of MTA-1 that mediates the FOG-2/MTA-1 interaction. We also demonstrate that knockdown of MTA protein expression dramatically impairs the ability of FOG-2 to repress GATA4 activity. Finally, we show that the zinc finger domain of MTA-1 is required for FOG-2-mediated transcriptional repression and that this domain interacts with RbAp46 and RbAp48 subunits of the NuRD complex. Together, these results demonstrate the importance of FOG-2/MTA/RbAp interactions for FOG-2-mediated transcriptional repression and further define the molecular interactions between the FOG Repression Motif and the NuRD complex.

Development of the heart valves is a complex process that relies on the successful remodeling of endocardial cushions. This process is dependent on a number of transcriptional regulators, including GATA4 and its interacting partner FOG-2. We have previously shown that the endocardial cushions in FOG-2 deficient mice are hyperplastic and fail to remodel appropriately, suggesting a defect late in endocardial cushion development. To elucidate this defect, we examined the later steps in endocardial cushion development including mesenchymal cell proliferation, differentiation, and apoptosis. We also measured myocardialization and endothelial-to-mesenchymal transformation (EMT) using previously described in vitro assays. We found no difference in the ability of the endocardial cushions to undergo myocardialization or in the rates of mesenchymal cell proliferation, differentiation, or apoptosis in the FOG-2 deficient cushions when compared to wild-type controls. However, using a collagen gel invasion assay, we found a 78% increase in outflow tract cushion EMT and a 35% increase in atrioventricular cushion EMT in the FOG-2 deficient mice when compared with wild-type mice. Taken together with GATA4′s known role in promoting EMT, these results suggest that FOG-2 functions in cardiac valve formation as an attenuator of EMT by repressing GATA4 activity within the developing endocardial cushions.

See related article, pages 431–441 Given the increasing prevalence of patients with congestive heart failure, there is a strong interest in identifying and isolating cardiac progenitor cells capable of differentiating into cardiomyocytes that could be used to repair a damaged, failing heart. Recent work in the zebrafish model system has suggested that the epicardium, the nonmyocyte epithelial layer of cells covering the heart, may play a critical role in the regeneration of injured myocardium.1 The epicardium has a distinct embryological origin from both the myocardium and endocardium. It arises from a mass of mesothelial cells termed the proepicardium, located on the wall of the embryonic pericardial cavity just dorsal and caudal to the developing heart.2 During early embryonic development, cells of the proepicardium migrate onto the heart at the atrioventricular junction and then spread over the surface of the heart to form a primitive epicardium. Some cells of the epicardium then undergo a mesenchymal transformation and invade into the subepicardial space. There these epicardial-derived cells further differentiate into cells that form the coronary vasculature as well as cardiac fibroblasts. Through this multistep differentiation pathway, the proepicardium serves as an important source for the noncardiomyocyte cellular component of the heart. Over the last few years, the pathways that regulate the development and differentiation of the proepicardium have begun to be revealed. First, the formation of the proepicardium …

GATA transcription factors are important regulators of both hematopoiesis (GATA-1/2/3) and cardiogenesis (GATA-4) in mammals. The transcriptional activities of the GATA proteins are modulated by their interactions with other transcription factors and with transcriptional coactivators and repressors. Recently, two related zinc finger proteins, U-shaped (USH) and Friend of GATA-1 (FOG) have been reported to interact with the GATA proteins Pannier and GATA-1, respectively, and to modulate their transcriptional activities in vitro and in vivo . In this report, we describe the molecular cloning and characterization of a third FOG-related protein, FOG-2. FOG-2 is an 1,151 amino acid nuclear protein that contains eight zinc finger motifs that are structurally related to those of both FOG and USH. FOG-2 is first expressed in the mouse embryonic heart and septum transversum at embryonic day 8.5 and is subsequently expressed in the developing neuroepithelium and urogenital ridge. In the adult, FOG-2 is expressed predominately in the heart, brain, and testis. FOG-2 associates physically with the N-terminal zinc finger of GATA-4 both in vitro and in vivo . This interaction appears to modulate specifically the transcriptional activity of GATA-4 because overexpression of FOG-2 in both NIH 3T3 cells and primary rat cardiomyocytes represses GATA-4-dependent transcription from multiple cardiac-restricted promoters. Taken together, these results implicate FOG-2 as a novel modulator of GATA-4 function during cardiac development and suggest a paradigm in which tissue-specific interactions between different FOG and GATA proteins regulate the differentiation of distinct mesodermal cell lineages.

Disorders of the vascular system are the leading cause of death and disability in the Western world. Mechanical interventions, such as angioplasty and bypass grafting, constitute the mainstay of treatment for end-stage occlusive lesions. Although initially successful in the majority of cases, the vascular response to injury and subsequent restenosis limits their long-term efficacy. Current work in the field of gene therapy has focused on the development of strategies to prevent these complications by the use of recombinant DNA technology. This review focuses on the latest advances in gene therapy for vascular disease, including the development of new vectors for vascular gene delivery, novel treatments for angioplasty-induced restenosis and vein graft intimal hyperplasia, and therapeutic angiogenesis.

Erythropoietin (Epo)-responsive anemia is a common and debilitating complication of chronic renal failure and human immunodeficiency virus infection. Current therapy for this condition involves repeated intravenous or subcutaneous injections of recombinant Epo. In this report, we describe the development of a novel muscle-based gene transfer approach that produces long-term expression of physiologically significant levels of Epo in the systemic circulation of mice. We have constructed a plasmid expression vector, pVRmEpo, that contains the murine Epo cDNA under the transcriptional control of the cytomegalovirus immediate early (CMV-IE) promoter, the CMV-IE 5' untranslated region, and intron A. A single intramuscular (i.m.) injection of as little as 10 micrograms of this plasmid into immunocompetent adult mice produced physiologically significant elevations in serum Epo levels and increased hematocrits from preinjection levels of 48 +/- 0.4% to levels of 64 +/- 3.3% 45 days after injection. Hematocrits in these animals remained elevated at greater than 60% for at least 90 days after a single i.m. injection of 10 micrograms of pVRmEpo. We observed a dose-response relationship between the amount of plasmid DNA injected and subsequent elevations in hematocrits. Mice injected once with 300 micrograms of pVRmEpo displayed 5-fold increased serum Epo levels and elevated hematocrits of 79 +/- 3.3% at 45 days after injection. The i.m. injected plasmid DNA remained localized to the site of injection as assayed by the PCR. We conclude that i.m. injection of plasmid DNA represents a viable nonviral gene transfer method for the treatment of acquired and inherited serum protein deficiencies.

Mutations in several transcription factors that regulate cardiac development have recently been described to cause congenital heart disease in humans. A greater understanding of the molecular mechanisms that regulate heart formation may help identify other genes that when mutated will result in human congenital heart disease. FOG-2 is one such gene that encodes a transcriptional corepressor expressed in the developing heart. It is critical for proper cardiac morphogenesis as mice deficient in this factor die during midgestation of cardiac malformations. We have previously shown that FOG-2 physically interacts with GATA4 and attenuates GATA49s ability to activate cardiac specific gene expression. This repression is mediated by a domain of FOG-2 localized to its N-terminus, termed the FOG repression motif. To gain further insights into the molecular mechanism responsible for this repression, we took a biochemical approach to identify factors that interact with FOG repression motif. Using MALDI-TOF mass spectrometry, we identified seven proteins from rat neonatal cardiac nuclear extracts that copurified with a FOG-2-GST fusion protein. All of these proteins have been previously described to be subunits of a nucleosome-remodeling complex called the NuRD complex. To determine which of the NuRD subunits directly interact with the FOG repression motif, we used a series of in vitro binding assays. We found that MTA-1 and MTA-2 specifically bound to the N-terminus of FOG-2 but not to a mutant form of the N-terminus that is unable to mediate repression. In situ hybridization revealed that both MTA-1 and MTA-2 are expressed in the developing heart during mouse embryogenesis. Taken together, these results suggest that FOG-2 mediates transcriptional repression during cardiac development by the recruitment of the NuRD complex to GATA-dependent promoters leading to the remodeling of the local chromatin structure and the attenuation of gene expression. This work was supported by NIH HL071063 and a grant from the Schweppe Foundation.

To test the proposal that ATPase activity is coupled to the rotation of muscle cross-bridges (myosin heads attached to actin), we have used saturation-transfer EPR to detect the rotational motion of spin-labeled myosin heads (subfragment 1; S1) bound to actin following the photolysis of caged ATP (a photoactivatable analog of ATP). In order to ensure that most of the heads were bound to actin in the presence of ATP, solutions contained high (200 microns) actin concentrations and were of low (36 mM) ionic strength. Sedimentation measurements indicated that 52 +/- 2% of the spin-labeled heads were attached in the steady state of ATP hydrolysis during EPR measurements. Five millimolar caged ATP was added to the actin-S1 solution in an EPR cell in the dark, with no effect on the intense saturation-transfer EPR signal, implying a rigid actin-S1 complex. A laser pulse produced 1 mM ATP, which decreased the signal rapidly to a brief steady-state level that indicated only slightly less rotational mobility than that of free heads. After correcting for the fraction of free heads, we conclude that the bound heads have an effective rotational correlation time of 1.0 +/- 0.3 microseconds, which is about 100 times shorter (faster) than that in the absence of ATP. To our knowledge, this is the first direct evidence that myosin heads undergo rotational motion when bound to actin during the ATPase cycle. It is likely that similar cross-bridge rotations occur during muscle contraction.

Purpose: Inappropriate or excessive vascular smooth muscle cell proliferation leads to the development of occlusive lesions in up to 50% of vein grafts. The purpose of this study was to test the hypothesis that induced overexpression of a cytostatic nonphosphorylatable form of the retinoblastoma protein (ΔRb) would attenuate neointimal thickening in experimental vein grafts. Methods: A replication-deficient adenovirus vector that encoded a nonphosphorylatable, constitutively active form of ΔRb was constructed (AdΔRb) and contained an NH 2 -terminal epitope tag from the influenza hemagglutinin molecule (HA). Forty-eight male New Zealand white rabbits underwent surgical exposure of the external jugular vein for transfection with either 3 × 10 10 plaque-forming units/mL AdΔRb (n = 16), 3 × 10 10 plaque-forming units/mL control adenovirus (AdBglII, n=15), or vehicle (n = 17) for 10 minutes at 120 mm Hg. After vector exposure, the vein was excised and interposed end-to-end into the carotid circulation. After 5 days, 12 grafts (four from each group) were excised and assayed for genomic ΔRb DNA with the polymerase chain reaction or for hemagglutinin molecule expression and localization with immunohistochemistry. The remainder of the grafts (n = 36) were perfusion-fixed after 4 weeks, and 5 μm sections prepared for digital planimetric analysis. Results: Polymerase chain reaction results identified the ΔRb gene only in the grafts that were transfected with AdΔRb. Immunohistochemical analysis results revealed transgene expression in most of the endothelial cells and in many of the smooth muscle cells. After 4 weeks, the grafts that were exposed to AdΔRb exhibited a 22% reduction in neointimal thickness (vehicle, 77 ± 7 μm; AdBglII, 75 ± 5 μm; AdΔRb, 60 ± 5 μm; P = .05), and medial thickness, luminal diameter, and other parameters were unchanged (medial thickness: vehicle, 72 ± 10 μm; AdBglII, 85 ± 7 μm; AdΔRb, 69 ± 9 μm; P = NS; luminal diameter: vehicle, 4.5 ± 0.2 mm; AdBglII, 4.4 ± 0.2 mm; AdΔRb, 4.7 ± 0.1 mm; P = NS). Conclusion: With this delivery system, adenoviral-mediated gene transfer is highly efficient and induced overexpression of ΔRb leads to a reduction in vein graft neointimal thickening. (J Vasc Surg 1999;29:874-83.)

Publisher Summary This chapter discusses that the condensed phases of the stable isotopes of helium, 3 He, and 4 He continue to be of high interest to scientists in general and to neutron scatterers in particular. This interest stems from the fact that these substances form the prototype examples in the nature of quantum solids and liquids of interacting bosons and fermions. A very meaningful comparison of the results of first-principles theoretical calculations, with experiment, is in fact possible for these materials, because the interatomic potential is reasonably simple and well known. Different regions of this potential can readily be probed in the experiments by varying the pressure and temperature to vary the interatomic distance, an extremely important advantage. The chapter highlights some of the most important features of the structure and excitations of the condensed phases of 3 He and 4 He; concentrating on the results from neutron scattering measurements, and on those theoretical developments that have direct consequences for neutron studies.