Always amazed by the mother nature ......
Randall's talk focuses on two screens he performed using Zebrafish as a model.
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Randall T Peterson, Lab Overview
Small molecules can be invaluable tools for studying and treating diseases, but discovering novel small molecules is a difficult and risky process. Many of the challenges of small molecule discovery stem from the inability of in vitro assays to model the complex physiology of disease. Consequently, the in vitro assays used in small molecule discovery are poor predictors of the beneficial and adverse effects of the small molecule when translated to an in vivo setting. We are circumventing these problems by performing high throughput small molecule discovery in vivo using zebrafish as a model organism. Areas of interest include cardiovascular disease, anemia, leukemia, and psychiatric disease.
I collected several of his publication here.
Nat Chem Biol. 2009 Apr;5(4):236-43. Epub 2009 Jan 26.
Discovering chemical modifiers of oncogene-regulated hematopoietic differentiation.
Yeh JR, Munson KM, Elagib KE, Goldfarb AN, Sweetser DA, Peterson RT.
Developmental Biology Laboratory, Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
It has been proposed that inhibitors of an oncogene's effects on multipotent hematopoietic progenitor cell differentiation may change the properties of the leukemic stem cells and complement the clinical use of cytotoxic drugs. Using zebrafish, we developed a robust in vivo hematopoietic differentiation assay that reflects the activity of the oncogene AML1-ETO. Screening for modifiers of AML1-ETO-mediated hematopoietic dysregulation uncovered unexpected roles of COX-2- and beta-catenin-dependent pathways in AML1-ETO function. This approach may open doors for developing therapeutics targeting oncogene function within leukemic stem cells.
Nat Med. 2008 Dec;14(12):1363-9. Epub 2008 Nov 30.
BMP type I receptor inhibition reduces heterotopic [corrected] ossification.
Yu PB, Deng DY, Lai CS, Hong CC, Cuny GD, Bouxsein ML, Hong DW, McManus PM, Katagiri T, Sachidanandan C, Kamiya N, Fukuda T, Mishina Y, Peterson RT, Bloch KD.Fibrodysplasia ossificans progressiva (FOP) is a congenital disorder of progressive and widespread postnatal ossification of soft tissues and is without known effective treatments. Affected individuals harbor conserved mutations in the ACVR1 gene that are thought to cause constitutive activation of the bone morphogenetic protein (BMP) type I receptor, activin receptor-like kinase-2 (ALK2). Here we show that intramuscular expression in the mouse of an inducible transgene encoding constitutively active ALK2 (caALK2), resulting from a glutamine to aspartic acid change at amino acid position 207, leads to ectopic endochondral bone formation, joint fusion and functional impairment, thus phenocopying key aspects of human FOP. A selective inhibitor of BMP type I receptor kinases, LDN-193189 (ref. 6), inhibits activation of the BMP signaling effectors SMAD1, SMAD5 and SMAD8 in tissues expressing caALK2 induced by adenovirus specifying Cre (Ad.Cre). This treatment resulted in a reduction in ectopic ossification and functional impairment. In contrast to localized induction of caALK2 by Ad.Cre (which entails inflammation), global postnatal expression of caALK2 (induced without the use of Ad.Cre and thus without inflammation) does not lead to ectopic ossification. However, if in this context an inflammatory stimulus was provided with a control adenovirus, ectopic bone formation was induced. Like LDN-193189, corticosteroid inhibits ossification in Ad.Cre-injected mutant mice, suggesting caALK2 expression and an inflammatory milieu are both required for the development of ectopic ossification in this model. These results support the role of dysregulated ALK2 kinase activity in the pathogenesis of FOP and suggest that small molecule inhibition of BMP type I receptor activity may be useful in treating FOP and heterotopic ossification syndromes associated with excessive BMP signaling.
PLoS One. 2008 Apr 9;3(4):e1947.
Identification of a novel retinoid by small molecule screening with zebrafish embryos.
Sachidanandan C, Yeh JR, Peterson QP, Peterson RT.
Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America.
Small molecules have played an important role in delineating molecular pathways involved in embryonic development and disease pathology. The need for novel small molecule modulators of biological processes has driven a number of targeted screens on large diverse libraries. However, due to the specific focus of such screens, the majority of the bioactive potential of these libraries remains unharnessed. In order to identify a higher proportion of compounds with interesting biological activities, we screened a diverse synthetic library for compounds that perturb the development of any of the multiple organs in zebrafish embryos. We identified small molecules that affect the development of a variety of structures such as heart, vasculature, brain, and body-axis. We utilized the previously known role of retinoic acid in anterior-posterior (A-P) patterning to identify the target of DTAB, a compound that caused A-P axis shortening in the zebrafish embryo. We show that DTAB is a retinoid with selective activity towards retinoic acid receptors gamma and beta. Thus, conducting zebrafish developmental screens using small molecules will not only enable the identification of compounds with diverse biological activities in a large chemical library but may also facilitate the identification of the target pathways of these biologically active molecules.
Development. 2008 Jan;135(2):401-10.
AML1-ETO reprograms hematopoietic cell fate by downregulating scl expression.
Yeh JR, Munson KM, Chao YL, Peterson QP, Macrae CA, Peterson RT.
Developmental Biology Laboratory, Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA 02129, USA. jyeh1@partners.org
AML1-ETO is one of the most common chromosomal translocation products associated with acute myelogenous leukemia (AML). Patients carrying the AML1-ETO fusion gene exhibit an accumulation of granulocyte precursors in the bone marrow and the blood. Here, we describe a transgenic zebrafish line that enables inducible expression of the human AML1-ETO oncogene. Induced AML1-ETO expression in embryonic zebrafish causes a phenotype that recapitulates some aspects of human AML. Using this highly tractable model, we show that AML1-ETO redirects myeloerythroid progenitor cells that are developmentally programmed to adopt the erythroid cell fate into the granulocytic cell fate. This fate change is characterized by a loss of gata1 expression and an increase in pu.1 expression in myeloerythroid progenitor cells. Moreover, we identify scl as an early and essential mediator of the effect of AML1-ETO on hematopoietic cell fate. AML1-ETO quickly shuts off scl expression, and restoration of scl expression rescues the effects of AML1-ETO on myeloerythroid progenitor cell fate. These results demonstrate that scl is an important mediator of the ability of AML1-ETO to reprogram hematopoietic cell fate decisions, suggesting that scl may be an important contributor to AML1-ETO-associated leukemia. In addition, treatment of AML1-ETO transgenic zebrafish embryos with a histone deacetylase inhibitor, Trichostatin A, restores scl and gata1 expression, and ameliorates the accumulation of granulocytic cells caused by AML1-ETO. Thus, this zebrafish model facilitates in vivo dissection of AML1-ETO-mediated signaling, and will enable large-scale chemical screens to identify suppressors of the in vivo effects of AML1-ETO.
Nat Chem Biol. 2008 Jan;4(1):33-41. Epub 2007 Nov 18.
Dorsomorphin inhibits BMP signals required for embryogenesis and iron metabolism.
Yu PB, Hong CC, Sachidanandan C, Babitt JL, Deng DY, Hoyng SA, Lin HY, Bloch KD, Peterson RT.
Cardiovascular Research Center and Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown, Massachusetts 02129, USA.
Bone morphogenetic protein (BMP) signals coordinate developmental patterning and have essential physiological roles in mature organisms. Here we describe the first known small-molecule inhibitor of BMP signaling-dorsomorphin, which we identified in a screen for compounds that perturb dorsoventral axis formation in zebrafish. We found that dorsomorphin selectively inhibits the BMP type I receptors ALK2, ALK3 and ALK6 and thus blocks BMP-mediated SMAD1/5/8 phosphorylation, target gene transcription and osteogenic differentiation. Using dorsomorphin, we examined the role of BMP signaling in iron homeostasis. In vitro, dorsomorphin inhibited BMP-, hemojuvelin- and interleukin 6-stimulated expression of the systemic iron regulator hepcidin, which suggests that BMP receptors regulate hepcidin induction by all of these stimuli. In vivo, systemic challenge with iron rapidly induced SMAD1/5/8 phosphorylation and hepcidin expression in the liver, whereas treatment with dorsomorphin blocked SMAD1/5/8 phosphorylation, normalized hepcidin expression and increased serum iron levels. These findings suggest an essential physiological role for hepatic BMP signaling in iron-hepcidin homeostasis.
Curr Biol. 2006 Jul 11;16(13):1366-72.
Artery/vein specification is governed by opposing phosphatidylinositol-3 kinase and MAP kinase/ERK signaling.
Hong CC, Peterson QP, Hong JY, Peterson RT.
Developmental Biology Laboratory, Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts 02129, and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
Angioblasts are multipotent progenitor cells that give rise to arteries or veins . Genetic disruption of the gridlock gene perturbs the artery/vein balance, resulting in generation of insufficient numbers of arterial cells . However, within angioblasts the precise biochemical signals that determine the artery/vein cell-fate decision are poorly understood. We have identified by chemical screening two classes of compounds that compensate for a mutation in the gridlock gene . Both target the VEGF signaling pathway and reveal two downstream branches emanating from the VEGF receptor with opposing effects on arterial specification. We show that activation of ERK (p42/44 MAP kinase) is a specific marker of early arterial progenitors and is among the earliest known determinants of arterial specification. In embryos, cells fated to contribute to arteries express high levels of activated ERK, whereas cells fated to contribute to veins do not. Inhibiting the phosphatidylinositol-3 kinase (PI3K) branch with GS4898 or known PI3K inhibitors, or by expression of a dominant-negative form of AKT promotes arterial specification. Conversely, inhibition of the ERK branch blocks arterial specification, and expression of constitutively active AKT promotes venous specification. In summary, chemical genetic analysis has uncovered unanticipated opposing roles of PI3K and ERK in artery/vein specification.
Nat Rev Drug Discov. 2005 Jan;4(1):35-44.
In vivo drug discovery in the zebrafish.
Zon LI, Peterson RT.
Howard Hughes Medical Institute, Division of Hematology/Oncology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
The zebrafish has become a widely used model organism because of its fecundity, its morphological and physiological similarity to mammals, the existence of many genomic tools and the ease with which large, phenotype-based screens can be performed. Because of these attributes, the zebrafish might also provide opportunities to accelerate the process of drug discovery. By combining the scale and throughput of in vitro screens with the physiological complexity of animal studies, the zebrafish promises to contribute to several aspects of the drug development process, including target identification, disease modelling, lead discovery and toxicology.
Nat Biotechnol. 2004 May;22(5):595-9. Epub 2004 Apr 18.
Chemical suppression of a genetic mutation in a zebrafish model of aortic coarctation.
Peterson RT, Shaw SY, Peterson TA, Milan DJ, Zhong TP, Schreiber SL, MacRae CA, Fishman MC.
Conventional drug discovery approaches require a priori selection of an appropriate molecular target, but it is often not obvious which biological pathways must be targeted to reverse a disease phenotype. Phenotype-based screens offer the potential to identify pathways and potential therapies that influence disease processes. The zebrafish mutation gridlock (grl, affecting the gene hey2) disrupts aortic blood flow in a region and physiological manner akin to aortic coarctation in humans. Here we use a whole-organism, phenotype-based, small-molecule screen to discover a class of compounds that suppress the coarctation phenotype and permit survival to adulthood. These compounds function during the specification and migration of angioblasts. They act to upregulate expression of vascular endothelial growth factor (VEGF), and the activation of the VEGF pathway is sufficient to suppress the gridlock phenotype. Thus, organism-based screens allow the discovery of small molecules that ameliorate complex dysmorphic syndromes even without targeting the affected gene directly.
Chem Biol. 2003 Oct;10(10):901-8.
Zebrafish-based small molecule discovery.
MacRae CA, Peterson RT.
Developmental Biology Laboratory and Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA 02129, USA.
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