Pia D. Bagamasbad

Sex: Female


Doctor of Philosophy in Molecular, Cellular and Developmental Biology, University of Michigan, 2012

Bachelor of Science in Molecular Biology and Biotechnology, University of the Philippines, 2001

Field of Specialization

Transcription factors

Molecular Biology





Article title: SUN-139 Luminescence-Based Drug Screen for Novel Androgen Receptor Antagonists for Prostate Cancer Therapy

Authors: Romie Angelo Azur, Isagani Padolina, Pia Bagamasbad

Publication title: Journal of the Endocrine Society 4(1), May 2020



The development and maintenance of the adult prostate is dependent on the action of androgens, which mediate its effect by binding to the androgen receptor (AR). Dysregulation in the AR signaling axis disrupts transcriptional homeostasis, shifting the balance towards uncontrolled proliferation and driving the progression towards prostate cancer (PCa). The prominent role of AR signaling in prostate carcinogenesis led to the development of androgen deprivation therapy (ADT) as the primary treatment strategy for managing PCa. Despite the success of ADT in early PCa cases, most patients develop resistance to ADT and the cancer ultimately recurs towards a lethal state termed castration-resistant prostate cancer (CRPC). Remarkably, AR signaling is still active in CRPC, suggesting that the progression towards CRPC is still reliant on AR activity. Current treatments are ineffective against CRPC, highlighting the need for alternative therapeutics that can combat the resistant nature of CRPC. To address the need for innovative approaches against CRPC, we used a robust luminescence-based bioassay that can identify novel AR antagonists. We screened plant extracts derived from local fauna by measuring their effect on AR-driven activity using a luciferase-based reporter assay in HeLa cells stably overexpressing hAR (HeLa-hAR). To identify candidate hits, HeLa-hAR cells were treated with DHT to induce AR-dependent luciferase activity, DHT with the AR antagonist bicalutamide as a positive control, and DHT plus the plant extracts. We identified one extract, A32, which showed significant inhibition of AR-dependent luciferase activity without having deleterious effects on cell viability. Secondary validation tests also showed that A32 exhibits a dose-dependent inhibition of AR-driven reporter activity. When testing the effect of A32 on gene expression in LNCaP cells, we observed a down-regulation in the expression of canonical AR target genes such as PSA to degrees similar to bicalutamide. These results suggest that A32 may be an AR antagonist or may target the AR signaling axis. Collectively, this study establishes the use of a luminescence-based reporter assay for the identification of novel AR antagonists from a plant extract library.


Article title: SAT-725 Alterations in the Phenotype and Epigenomic Landscape of Luminal Breast Cancer Following Long-Term Nanomolar Exposure to Bisphenol a (BPA)

Authors: Jason Tan Liwag, Michael Cu Velarde, Pia Bagamasbad

Publication title: Journal of the Endocrine Society 4(1), May 2020



Breast cancer (BCa) is the leading cause of female cancer-related death worldwide. Luminal BCa accounts for at least 70% of all BCa and is characterized by its hormone dependence, particularly to estrogen. Endocrine disruptors may function to exert the pro-tumorigenic effects of estrogen in proxy following environmental exposure. Bisphenol A (BPA) is a ubiquitous endocrine disruptor shown to increase risk towards developing BCa in multiple in vivo mammalian models and in vitro human breast models. Despite this, there is limited information on the phenotypic and epigenetic effects of nanomolar BPA following long-term exposure particularly in the context of BCa stem cell population, which accumulate the ‘cellular insult’ and are likely to pass such information down through epigenetic mechanisms. We hypothesize that BPA affects the epigenome, in part, by altering the regulation of DNA methyltransferases (DNMTs) since BPA disrupts transcriptional and translational regulation of DNMTs in various other tissue types such as the brain, testis and prostate. In this study, MCF7 cells were chronically (>4 weeks) cultured with nanomolar doses of BPA, and subsequently subjected to phenotypic assays and gene expression analysis in monolayer or mammosphere culture. Gene expression analysis revealed a downregulation of DNMT3A and ESR1 following long-term exposure to BPA in mammosphere culture of MCF7 cells, but not in monolayer culture. This is accompanied by alterations in mammosphere morphology, reduction in mammosphere size, an increase in the mammosphere number, and an increase in the CD49f+ population, indicating a positive contribution of BPA to stemness. However, there are no significant changes in proliferation, apoptotic rate, and metastasis in both monolayer and mammosphere culture. Future analysis includes assessment of genome-wide alterations in DNA methylation patterns in these chronically exposed MCF7 mammospheres, as well as identifying estrogen responsiveness, chemotherapeutic response, and self-renewal properties of these cancer cells.


Article title: SAT-132 The Secretory Vesicle Membrane Protein, CYB561, Promotes the Growth and Metastatic Potential of Castration-Resistant Neuroendocrine Prostate Cancer

Authors: Kevin Christian V. Olarte, Pia Bagamasbad

Publication title: Journal of the Endocrine Society 4(1), May 2020



An increase in the population of neuroendocrine (NE) differentiated (NED) cells and their secretory products are closely correlated with prostate cancer (PCa) resistance to existing therapies and eventual progression to castration-resistant PCa (CRPC). It is hypothesized that NED cells secrete neuropeptides that support tumor growth and induce aggressiveness of adjacent proliferating tumor cells through a paracrine mechanism. A gene that is constitutively expressed in secretory vesicles of NE cells, and has been previously found to be highly expressed in CRPC and cancer of several tissues is Cytochrome b561 (CYB561). The CYB561 gene encodes a secretory vesicle transmembrane protein that primarily functions in the regeneration of ascorbic acid, a necessary step in the α-amidation activation process in the biosynthesis of most neuropeptides. The CYB561 protein also exhibits ferrireductase activity and may contribute in regulating iron transport and metabolism, which are two other pathways often dysregulated in cancer. These findings led us to hypothesize that CYB561 may be a key player in the NE differentiation process that drives the progression of prostate cancers into the more aggressive NE subtype. In our study, we found that CYB561 expression is higher in metastatic and NE PCa (NEPC) models compared to normal prostate epithelia, and that its expression is not affected by androgen treatment or steroid deprivation. Lentiviral-mediated knockdown of CYB561 in the NEPC cell line, PC-3, decreased the expression of genes involved in NE differentiation and labile iron pool storage, decreased cell proliferation, reduced cell survival in a colony formation assay, and slowed down cell migration in a wound-healing assay. Treatment of normal prostate epithelial cells, PNT1A, with conditioned media from CYB561 knockdown PC-3 cells led to a decrease in proliferation rate when compared to treatment of PNT1A cells with media from CYB561 expressing (control) PC-3 cells. Taken together, our findings demonstrate the role of CYB561 in supporting the growth and metastatic potential of NEPC cells, and highlights the potential use of CYB561 as a therapeutic target and biomarker that can be used to identify more aggressive disease.

Full text available upon request to the author


Article title:  Differential modulation of the androgen receptor for prostate cancer therapy depends on the DNA response element

Authors: Steven Kregel, Pia Bagamasbad, Shihan He, Elizabeth LaPensee, et al.

Publication title: Nucleic Acids Research 48(9), March 2020



Androgen receptor (AR) action is a hallmark of prostate cancer (PCa) with androgen deprivation being standard therapy. Yet, resistance arises and aberrant AR signaling promotes disease. We sought compounds that inhibited genes driving cancer but not normal growth and hypothesized that genes with consensus androgen response elements (cAREs) drive proliferation but genes with selective elements (sAREs) promote differentiation. In a high-throughput promoter-dependent drug screen, doxorubicin (dox) exhibited this ability, acting on DNA rather than AR. This dox effect was observed at low doses for multiple AR target genes in multiple PCa cell lines and also occurred in vivo. Transcriptomic analyses revealed that low dox downregulated cell cycle genes while high dox upregulated DNA damage response genes. In chromatin immunoprecipitation (ChIP) assays with low dox, AR binding to sARE-containing enhancers increased, whereas AR was lost from cAREs. Further, ChIP-seq analysis revealed a subset of genes for which AR binding in low dox increased at pre-existing sites that included sites for prostate-specific factors such as FOXA1. AR dependence on cofactors at sAREs may be the basis for differential modulation by dox that preserves expression of genes for survival but not cancer progression. Repurposing of dox may provide unique opportunities for PCa treatment.


Article title: Coordinated transcriptional regulation by thyroid hormone and glucocorticoid interaction in adult mouse hippocampus-derived neuronal cells

Authors:  Pia Bagamasbad, Jose Ezekiel C. Espina, Joseph R. Knoedler, Arasakumar Subramani, et al. 

Publication title: PLoS ONE 14(7): e0220378, July 2019



The hippocampus is a well-known target of thyroid hormone (TH; e.g., 3,5,3'-triiodothyronine-T3) and glucocorticoid (GC; e.g., corticosterone-CORT) action. Despite evidence that TH and GC play critical roles in neural development and function, few studies have identified genes and patterns of gene regulation influenced by the interaction of these hormones at a genome-wide scale. In this study we investigated gene regulation by T3, CORT, and T3 + CORT in the mouse hippocampus-derived cell line HT-22. We treated cells with T3, CORT, or T3 + CORT for 4 hr before cell harvest and RNA isolation for microarray analysis. We identified 9 genes regulated by T3, 432 genes by CORT, and 412 genes by T3 + CORT. Among the 432 CORT-regulated genes, there were 203 genes that exhibited an altered CORT response in the presence of T3, suggesting that T3 plays a significant role in modulating CORT-regulated genes. We also found 80 genes synergistically induced, and 73 genes synergistically repressed by T3 + CORT treatment. We performed in silico analysis using publicly available mouse neuronal chromatin immunoprecipitation-sequencing datasets and identified a considerable number of synergistically regulated genes with TH receptor and GC receptor peaks mapping within 1 kb of chromatin marks indicative of hormone-responsive enhancer regions. Functional annotation clustering of synergistically regulated genes reveal the relevance of proteasomal-dependent degradation, neuroprotective effect of growth hormones, and neuroinflammatory responses as key pathways to how TH and GC may coordinately influence learning and memory. Taken together, our transcriptome data represents a promising exploratory dataset for further study of common molecular mechanisms behind synergistic TH and GC gene regulation, and identify specific genes and their role in processes mediated by cross-talk between the thyroid and stress axes in a mammalian hippocampal model system.


Article title: Deciphering the Regulatory Logic of an Ancient, Ultraconserved Nuclear Receptor Enhancer Module

Authors: Pia Bagamasbad, Ronald M. Bonett, Laurent M. Sachs, Nicolas Buisine, et al.

Publication title: Molecular Endocrinology 29(6): me20141349, April 2015



Cooperative, synergistic gene regulation by nuclear receptors (NRs) can increase sensitivity and amplify cellular responses to hormones. We investigated thyroid hormone (TH) and glucocorticoid (GC) synergy on the Kr )ppel-like factor 9 (Klf9) gene, which codes for a zinc finger transcription factor involved in development and homeostasis of diverse tissues. We identified regions of the Xenopus and mouse Klf9 genes 5 to 6 kb upstream of the transcription start sites that supported synergistic transactivation by TH plus GC. Within these regions we found an orthologous sequence of ∼180 bp that is highly conserved among tetrapods, but absent in other chordates, and possesses chromatin marks characteristic of an enhancer element. The Xenopus and mouse ∼180 bp DNA element conferred synergistic transactivation by hormones in transient transfection assays, so we designate this the Klf9 Synergy Module (KSM). We identified binding sites within the mouse KSM for TH receptor (TR), GC receptor (GR) and nuclear factor kappa B. Thyroid hormone strongly increased recruitment of liganded GR and serine 5 phosphorylated (initiating) RNA polymerase II (pol II) to chromatin at the KSM, suggesting a mechanism for transcriptional synergy. The KSM is transcribed to generate long noncoding RNAs which are also synergistically induced by combined hormone treatment, and the KSM interacts with the Klf9 promoter and a far upstream region through chromosomal looping. Our findings support that the KSM plays a central role in hormone regulation of vertebrate Klf9 genes, it evolved in the tetrapod lineage, and has been maintained by strong stabilizing selection.

Full text available upon request to the author


Article title: Molecular Basis for Glucocorticoid Induction of the Kruppel-Like Factor 9 Gene in Hippocampal Neurons

Authors: Pia Bagamasbad, Tim Ziera, Steffen A. Borden, Ronald M. Bonett, et al.

Publication title: Endocrinology 153(11), September 2012



Stress has complex effects on hippocampal structure and function, which consequently affects learning and memory. These effects are mediated in part by circulating glucocorticoids (GC) acting via the intracellular GC receptor (GR) and mineralocorticoid receptor (MR). Here, we investigated GC regulation of Krüppel-like factor 9 (KLF9), a transcription factor implicated in neuronal development and plasticity. Injection of corticosterone (CORT) in postnatal d 6 and 30 mice increased Klf9 mRNA and heteronuclear RNA by 1 h in the hippocampal region. Treatment of the mouse hippocampal cell line HT-22 with CORT caused a time- and dose-dependent increase in Klf9 mRNA. The CORT induction of Klf9 was resistant to protein synthesis inhibition, suggesting that Klf9 is a direct CORT-response gene. In support of this hypothesis, we identified two GR/MR response elements (GRE/MRE) located -6.1 and -5.3 kb relative to the transcription start site, and we verified their functionality by enhancer-reporter, gel shift, and chromatin immunoprecipitation assays. The -5.3-kb GRE/MRE is largely conserved across tetrapods, but conserved orthologs of the -6.1-kb GRE/MRE were only detected in therian mammals. GC treatment caused recruitment of the GR, histone hyperacetylation, and nucleosome removal at Klf9 upstream regions. Our findings support a predominant role for GR, with a minor contribution of MR, in the direct regulation of Klf9 acting via two GRE/MRE located in the 5'-flanking region of the gene. KLF9 may play a key role in GC actions on hippocampal development and plasticity.

Full text available upon request to the author


Article title: AVR/NAVR deficiency lowers blood pressure and differentially affects urinary concentrating ability, cognition, and anxiety-like behavior in male and female mice

Authors: Victoria Herrera, Pia Bagamasbad, Julius L. Decano, Nelson Ruiz-Opazo

Publication title: Physiological Genomics 43(1): 32-42, October 2010



Arginine vasopressin (AVP) and angiotensin II (ANG II) are distinct peptide hormones involved in multiple organs modulating renal, cardiovascular, and brain functions. They achieve these functions via specific G protein-coupled receptors, respectively. The AVR/NAVR locus encodes two overlapping V2-type vasopressin isoreceptors: angiotensin-vasopressin receptor (AVR) responding to ANG II and AVP equivalently, and nonangiotensin vasopressin receptor (NAVR), which binds vasopressin exclusively. AVR and NAVR are expressed from a single gene by alternative promoter usage that is synergistically upregulated by testosterone and estrogen. This study tested the hypothesis that AVR/NAVR modulates urinary concentrating ability, blood pressure, and cognitive performance in vivo in a sex-specific manner. We developed a C57BL/6 inbred AVR/NAVR(-/-) knockout mouse that showed lower blood pressure in both male and female subjects and a urinary-concentrating defect restricted to male mice. We also detected sex-specific effects on cognitive and anxiety-like behaviors. AVR/NAVR(-/-) male mice exhibited impaired visuospatial and associative learning, while female mice showed improved performance in both type of cognition. AVR/NAVR deficiency produced an anxiolytic-like effect in female mice, while males were unaffected. Analysis of AVR- and NAVR-mediated phosphorylation/dephosphorylation of signaling proteins revealed activation/deactivation of known modulators of cognitive function. Our studies identify AVR/NAVR as key receptors involved in blood pressure regulation and sex-specific modulation of renal water homeostasis, cognitive function, and anxiety-like behavior. As such, the AVR/NAVR receptor system provides a molecular mechanism for sexually diergic traits and a putative common pathway for the emerging association of hypertension and cognitive decline and dementia.

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Article title: Mechanisms and significance of nuclear receptor auto- and cross-regulation

Authors: Pia Bagamasbad and Robert J. Denver

Publication title: General and Comparative Endocrinology 170(1): 3-17, March 2010



The number of functional hormone receptors expressed by a cell in large part determines its responsiveness to the hormonal signal. The regulation of hormone receptor gene expression is therefore a central component of hormone action. Vertebrate steroid and thyroid hormones act by binding to nuclear receptors (NR) that function as ligand-activated transcription factors. Nuclear receptor genes are regulated by diverse and interacting intracellular signaling pathways. Nuclear receptor ligands can regulate the expression of the gene for the NR that mediates the hormone's action (autoregulation), thus influencing how a cell responds to the hormone. Autoregulation can be either positive or negative, the hormone increasing or decreasing, respectively, the expression of its own NR. Positive autoregulation (autoinduction) is often observed during postembryonic development, and during the ovarian cycle, where it enhances cellular sensitivity to the hormonal signal to drive the developmental process. By contrast, negative autoregulation (autorepression) may become important in the juvenile and adult for homeostatic negative feedback responses. In addition to autoregulation, a NR can influence the expression other types of NRs (cross-regulation), thus modifying how a cell responds to a different hormone. Cross-regulation by NRs is an important means to temporally coordinate cell responses to a subsequent (different) hormonal signal, or to allow for crosstalk between hormone signaling pathways.

Full text available upon request to the author


Article title: Stressor and Glucocorticoid-Dependent Induction of the Immediate Early Gene Kruppel-Like Factor 9: Implications for Neural Development and Plasticity

Authors: Ronald M. Bonett, Fang Hu, Pia Bagamasbad, Robert J. Denver

Publication title: Endocrinology 150(4): 1757-65, December 2008



Krüppel-like factor 9 (KLF9) is a thyroid hormone-induced, immediate early gene implicated in neural development in vertebrates. We analyzed stressor and glucocorticoid (GC)-dependent regulation of KLF9 expression in the brain of the frog Xenopus laevis, and investigated a possible role for KLF9 in neuronal differentiation. Exposure to shaking/confinement stressor increased plasma corticosterone (CORT) concentration, and KLF9 immunoreactivity in several brain regions, which included the medial amygdala and bed nucleus of the stria terminalis, anterior preoptic area (homologous to the mammalian paraventricular nucleus), and optic tectum (homologous to the mammalian superior colliculus). The stressor-induced KLF9 mRNA expression in the brain was blocked by pretreatment with the GC receptor antagonist RU486, or mimicked by injection of CORT. Treatment with CORT also caused a rapid and dose-dependent increase in KLF9 mRNA in X. laevis XTC-2 cells that was resistant to inhibition of protein synthesis. The action of CORT on KLF9 expression in XTC-2 cells was blocked by RU486, but not by the mineralocorticoid receptor antagonist spironolactone. To test for functional consequences of up-regulation of KLF9, we introduced a KLF9 expression plasmid into living tadpole brain by electroporation-mediated gene transfer. Forced expression of KLF9 in tadpole brain caused an increase in Golgi-stained cells, reflective of neuronal differentiation/maturation. Our results support that KLF9 is a direct, GC receptor target gene that is induced by stress, and functions as an intermediary in the actions of GCs on brain gene expression and neuronal structure.

Full text available upon request to the author


Article title: Sex-specific hippocampus-dependent cognitive deficits and increased neuronal autophagy in DEspR haploinsufficiency in mice

Authors: Victoria Herrera, Julius L. Decano, Pia Bagamasbad, Timothy Kufahl, et al.

Publication title: Physiological Genomics 12(35):316-29, November 2008



Aside from abnormal angiogenesis, dual endothelin-1/VEGF signal peptide-activated receptor deficiency (DEspR(-/-)) results in aberrant neuroepithelium and neural tube differentiation, thus elucidating DEspR's role in neurogenesis. With the emerging importance of neurogenesis in adulthood, we tested the hypothesis that nonembryonic-lethal DEspR haploinsufficiency (DEspR(+/-)) perturbs neuronal homeostasis, thereby facilitating aging-associated neurodegeneration. Here we show that, in male mice only, DEspR-haploinsufficiency impaired hippocampus-dependent visuospatial and associative learning and induced noninflammatory spongiform changes, neuronal vacuolation, and loss in the hippocampus, cerebral cortex, and subcortical regions, consistent with autophagic cell death. In contrast, DEspR(+/-) females exhibited better cognitive performance than wild-type females and showed absence of neuropathological changes. Signaling pathway analysis revealed DEspR-mediated phosphorylation of activators of autophagy inhibitor mammalian target of rapamycin (mTOR) and dephosphorylation of known autophagy inducers. Altogether, the data demonstrate DEspR-mediated diametrical, sex-specific modulation of cognitive performance and autophagy, highlight cerebral neuronal vulnerability to autophagic dysregulation, and causally link DEspR haploinsufficiency with increased neuronal autophagy, spongiosis, and cognitive decline in mice.


Article title: Overlapping genes in Nalp6/PYPAF5 locus encode two V2-type vasopressin isoreceptors: Angiotensin-vasopressin receptor (AVR) and non-AVR

Authors: Victoria Herrera, Pia Bagamasbad, Tamara Didishvili, Julius L. Decano, et al. 

Publication title: Physiological Genomics 34(1): 65-77, June 2008



The angiotensin-vasopressin receptor (AVR) responds with equivalent affinities to angiotensin II (ANG II) and vasopressin and is coupled to adenylate cyclase and hence a V2-type vasopressin receptor. AVR maps to the Nalp6 locus and overlaps with the larger Nalp6/PYPAF5 reported to be a T cell/granulocyte-specific, cytoplasmic-specific proapoptotic protein, thus questioning the existence of AVR. Here we confirm, through different experimental modalities, that AVR is distinct from Nalp6/PYPAF5 based on different mRNA and protein sizes, subcellular localization, and tissue-specific expression patterns. Binding studies of PYPAF5-specific Cos1 transfectants detect high-affinity binding to vasopressin but not ANG II, thus assigning PYPAF5 as a non-AVR (NAVR). Signaling array analysis reveals that AVP stimulation of AVR- and NAVR-specific Cos1 transfectants results in diametrical activation as well as coactivation of signaling pathways known to mediate renal sodium and water balance. Likewise, ANG II stimulation of Cos1-AVR transfectants reveals a signaling profile distinct from that of AVP-stimulated Cos1-AVR transfectants. Analysis of genomic organization of the AVR/NAVR locus shows an overlapping gene arrangement with alternative promoter usage resulting in different NH(2) termini for NAVR and AVR. In addition to core promoter elements, androgen and estrogen response elements are detected. Promoter analysis of NAVR/AVR 5'-regulatory region detects transcriptional upregulation by testosterone and synergistic upregulation by testosterone and estrogen, thus suggesting that AVR and/or NAVR contribute to sex-specific V2-type vasopressin-mediated effects. Altogether, confirmation of AVR and identification of NAVR as vasopressin receptors are concordant with emerging vasopressin functions not attributable to V1a, V1b, or V2 receptors and add molecular bases for the multifunctional complexity of vasopressin-mediated functions and regulation.

Article title: A Role for Basic Transcription Element-binding Protein 1 (BTEB1) in the Autoinduction of Thyroid Hormone Receptor

Authors: Pia Bagamasbad, Kembra L. Howdeshell, Laurent M. Sachs, Barbara Dermeneix, et al.

Publication title: Journal of Biological Chemistry 283(4): 2275-85, February 2008



Thyroid hormone (T3) induces gene regulation programs necessary for tadpole metamorphosis. Among the earliest responses to T3 are the up-regulation of T3 receptor β (TRβ; autoinduction) and BTEB1 (basic transcription element-binding protein 1). BTEB1 is a member of the Krüppel family of transcription factors that bind to GC-rich regions in gene promoters. The proximal promoter of the Xenopus laevis TrβA gene has seven GC-rich sequences, which led us to hypothesize that BTEB1 binds to and regulates TrβA. In tadpoles and the frog fibroblast-derived cell line XTC-2, T3 up-regulated Bteb1 mRNA with faster kinetics than TrβA, and Bteb1 mRNA correlated with increased BTEB1 protein expression. BTEB1 bound to GC-rich sequences in the proximal TrβA promoter in vitro. By using chromatin immunoprecipitation assay, we show that BTEB1 associates with the TrβA promoter in vivo in a T3 and developmental stage-dependent manner. Induced expression of BTEB1 in XTC-2 cells caused accelerated and enhanced autoinduction of the TrβA gene. This enhancement was lost in N-terminal truncated mutants of BTEB1. However, point mutations in the zinc fingers of BTEB1 that destroyed DNA binding did not alter the activity of the protein on TrβA autoinduction, suggesting that BTEB1 can function in this regard through protein-protein interactions. Our findings support the hypothesis that BTEB1 associates with the TrβA promoter in vivo and enhances autoinduction, but this action does not depend on its DNA binding activity. Cooperation among the protein products of immediate early genes may be a common mechanism for driving developmental signaling pathways.

Full text available upon request to the author


Article title: Genetics and pharmacogenomics.

Authors: N. Glorosio, Victoria Herrera, Pia Bagamasbad, Fabiana Filigheddu, et al.

Publication title: High Blood Pressure & Cardiovascular Prevention 14(3): 145, September 2007



Essential hypertension remains a major risk factor for cardiovascular and cerebrovascular diseases. As a complex multifactorial disease, elucidation of susceptibility loci remains elusive. ATP1A1 and Dear are candidate genes for 2 closely linked rat chromosome-2 blood pressure quantitative trait loci. Because corresponding human syntenic regions are on different chromosomes, investigation of ATP1A1 (chromosome [chr]-1p21) and Dear (chr-4q31.3) facilitates genetic analyses of each blood pressure quantitative trait locus in human hypertension. Here we report the association of human ATP1A1 (P<0.000005) and Dear (P<0.03) with hypertension in a relatively isolated, case/control hypertension cohort from northern Sardinia by single-nucleotide polymorphism haplotype analysis. Sex-specific haplotype analyses detected stronger association of both loci with hypertension in males than in females. Haplotype trend-regression analyses support ATP1A1 and Dear as independent susceptibility loci and reveal haplotype-specific association with hypertension and normotension, thus delineating haplotype-specific subsets of hypertension. Although investigation in other cohorts needs to be performed to determine genetic effects in other populations, haplotype subtyping already allows systematic stratification of susceptibility and, hence, clinical heterogeneity, a prerequisite for unraveling the polygenic etiology and polygene-environment interactions in essential hypertension. As hypertension susceptibility genes, coexpression of ATP1A1 and Dear in both renal tubular cells and vascular endothelium suggest a cellular pathogenic scaffold for polygenic mechanisms of hypertension, as well as the hypothesis that ATP1A1 and/or Dear could contribute to the known renal and vascular endothelial dysfunction associated with essential (polygenic) hypertension.

Full text available upon request to the author


Article title: Gender-Specific Association of ATP1a1 and Dear Haplotypes with Essential Hypertension

Authors: N. Glorosio, Victoria Herrera, Pia Bagamasbad, Fabiana Filigheddu, et al.

Publication title: High Blood Pressure & Cardiovascular Prevention 14(3): 145-196, Januaary 2007



No abstract available

Full text available upon request to the author


Article title: The Escherichia coli GTPase CgtAE Is Involved in Late Steps of Large Ribosome Assembly

Authors: Mengxi Jiang, Kaustuv Datta, Angela K. Walker, John Strahler, et al.

Publication title: Journal of Bacteriology 188(19): 6757-70, November 2006



The bacterial ribosome is an extremely complicated macromolecular complex the in vivo biogenesis of which is poorly understood. Although several bona fide assembly factors have been identified, their precise functions and temporal relationships are not clearly defined. Here we describe the involvement of an Escherichia coli GTPase, CgtAE, in late steps of large ribosomal subunit biogenesis. CgtAE belongs to the Obg/CgtA GTPase subfamily, whose highly conserved members are predominantly involved in ribosome function. Mutations in CgtAE cause both polysome and rRNA processing defects; small- and large-subunit precursor rRNAs accumulate in a cgtAE mutant. In this study we apply a new semiquantitative proteomic approach to show that CgtAE is required for optimal incorporation of certain late-assembly ribosomal proteins into the large ribosomal subunit. Moreover, we demonstrate the interaction with the 50S ribosomal subunits of specific nonribosomal proteins (including heretofore uncharacterized proteins) and define possible temporal relationships between these proteins and CgtAE. We also show that purified CgtAE associates with purified ribosomal particles in the GTP-bound form. Finally, CgtAE cofractionates with the mature 50S but not with intermediate particles accumulated in other large ribosome assembly mutants.


Article title: Embryonic lethality in Dear gene-deficient mice: New player in angiogenesis

Authors: Victoria Herrera, Lorenz R. B. Ponce, Pia Bagamasbad, Benjamin D. VanPelt, et al. 

Publication title: Physiological Genomics 23(3): 257-268, December 2005



The dual endothelin-1/angiotensin II receptor (Dear) binds endothelin-1 (ET-1) and angiotensin II (ANG II) with equal affinities in the Dahl S/JRHS rat strain. To elucidate its physiological significance within the context of multiple receptor isoforms and diverse ET-1 and ANG II functions spanning blood pressure regulation, tumor proliferation, and angiogenesis, we characterized mouse Dear and Dear-deficient mice. Unlike null mutant models of ET-1, ANG II, and all other ET-1 and ANG II receptors, Dear(-/-) deficiency results in impaired angiogenesis, dysregulated neuroepithelial development, and embryonic lethality by embryonic day 12.5. Interestingly, mouse Dear does not bind ANG II, similar to Dahl R/JRHS rat Dear, but binds ET-1 and vascular endothelial growth factor (VEGF) signal peptide (VEGFsp) with equal affinities, suggesting a putative novel multifunction for VEGFsp and a parsimonious mechanism for coordination of VEGF-induced and Dear-mediated pathways. Consistent with its developmental angiogenic role, Dear inhibition results in decreased tumor growth in B16-F10 melanoma cell-induced subcutaneous tumor in female Dear(+/-)/C57BL6BC10 mice, but not in males (age 3.5 mo), and in 127Cs radiation-induced orthotopic mammary tumors in Sprague-Dawley female rats (age range 3-6.5 mo). Altogether, the data identify Dear as a new player in angiogenesis during development downstream to, and nonredundant with, VEGF-mediated pathways, as well as a putative modulator of tumor angiogenesis acting within a gender-specific paradigm.


Article title: Analysis of gender-specific atherosclerosis susceptibility in transgenic [hCETP]25(DS) rat model

Authors: Victoria Herrera, Aristides Tsikoudakis, Tamara Didishvili, Lorenz R.B. Ponce, et al.

Publication title: Atherosclerosis 177(1):9-18, December 2004



Epidemiological and clinical data demonstrate differences in atherosclerotic coronary heart disease prevalence between age-matched men and premenopausal women. Mechanisms underlying relative athero-susceptibility in men and athero-resistance in premenopausal women remain to be elucidated. Lack of informative animal models hinders research. We report here a moderate-expresser line transgenic for human cholesteryl ester transfer protein (CETP) in the Dahl salt-sensitive hypertensive rat strain, Tg25, that recapitulates premenopausal female athero-resistance. Having ascertained identical genetic background, environmental factors, and equivalent CETP hepatic RNA levels, we detect worse hypercholesterolemia, hypertriglyceridemia, coronary plaques and survival outcome in Tg25 male rats compared with Tg25 females. Hepatic transcription profiles of Tg25 males and females normalized to respective gender- and age-matched non-transgenic controls exhibit significant differences. Genes implicated on hierarchical cluster analysis and quantitative real-time RT-PCR pinpoint pathways associated with coronary plaque progression such as inflammation and arachidonic acid epoxygenation, and not just cholesterol metabolism pathways. The data demonstrate gender-specific factors as key modulators of atherosclerosis phenotype and suggest a possible role for the liver in atheroma progression as a large organ source of proatherogenic systemic factors.

Full text available upon request to the author


Article title: Attenuated Hippocampus-Dependent Learning and Memory Decline in Transgenic TgAPPswe Fischer-344 Rats

Authors: Nelson Ruiz-Opazo, Kenneth S. Osik, Lyle V. Lopez, Pia Bagamasbad, et al

Publication title: Molecular Medicine 10(1-6):36-44, January 2004



Alzheimer's disease (AD) is characterized by increased beta amyloid (Abeta) levels, extracellular Abeta deposits in senile plaques, neurofibrillary tangles, and neuronal loss. However, the physiological role of normal levels of Abeta and its parent protein, the amyloid precursor protein (APP) are unknown. Here we report that low-level transgenic (Tg) expression of the Swedish APP mutant gene (APPswe) in Fischer-344 rats results in attenuated age-dependent cognitive performance decline in 2 hippocampus-dependent learning and memory tasks compared with age-matched nontransgenic Fischer-344 controls. TgAPPswe rats exhibit mild increases in brain APP mRNA (56.8%), Abeta-42 (21%), and Abeta-40 (6.1%) peptide levels at 12 mo of age, with no extracellular Abeta deposits or senile plaques at 6, 12, and 18 mo of age, whereas 3- to 6-fold increases in Abeta levels are detected in plaque-positive human AD patients and transgenic mouse models. The data support the hypothesis that a threshold paradigm underlies Abeta-related pathology, below which APP expression may play a physiological role in specific hippocampus-dependent tasks, most likely related to its neurotrophic role.