Understanding the mechanisms directing progressive specification of heart cells from multipotent cardiovascular progenitors is essential for the development of regenerative therapies using induced pluripotent stem (iPS) cells. A simple chordate model system, the tunicate Ciona intestinalis, will be used to analyze the cellular and molecular mechanisms that determine muscle-type specification in the cardiogenic lineage. In Ciona embryos, the bilateral pairs of precardiac cells, called trunk ventral cells (TVCs), undergo stereotyped asymmetric cell divisions that distinguish the heart from the atrial siphon muscle (ASM) precursors. The latter then migrate toward the dorso-lateral atrial siphon placode. Following asymmetric divisions of the TVCs, the genes encoding the transcription factors COE and Islet are specifically up- regulated in the ASMs. In addition, COE is necessary and sufficient to block heart specification and promote the ASM fate, including expression of an ASM-specific Islet enhancer and cell migration toward the dorsal side of the larva. Finally, targeted expression of the constitutively active Notch intracellular domain using a TVC-specific enhancer is sufficient to inhibit ASM- specific expression of COE, Islet and cell migration. These observations led to the hypothesis that the initial asymmetric divisions result in heart-specific Notch signaling, which blocks ASM fate specification, possibly by inhibiting the expression of COE. In order to test this hypothesis, the cis-regulatory sequences that control ASM-specific expression of COE will be isolated and characterized, and the function of Notch signaling upstream of COE will be determined. The expression and localization patterns of endogenous regulators and effectors of Notch signaling will be documented in order to gain insight into the mechanisms that polarize the Notch signal during asymmetric TVC divisions. The effects of Notch signaling, COE and Islet on heart vs. ASM fate specification and cell migration will be analyzed using previously established assays in order to begin to characterize the epistatic relationships between these regulators. Finally, whole genome gene expression changes underlying heart vs. ASM fate specification will be documented by obtaining heart and ASM-specific transcription profiles using fluorescence activated cell sorting and microarrays. The results obtained upon completion of this project will characterize the regulation and function of COE, a novel negative regulator of heart fate specification, and illuminate the cellular and molecular mechanisms controlling muscle fate specification and cell migration in the cardiogenic lineage.

Public Health Relevance

Personalized medicine utilizing induced pluripotent stem cells based regenerative medicine represents a novel promising avenue for the treatment of cardiovascular diseases and will require a thorough understanding of the cellular and molecular mechanisms whereby naive cells are determined to form functional heart tissue. While studying these basic mechanisms using a simple invertebrate model, the tunicate Ciona intestinalis, we recently identified the transcription factor COE as a novel negative regulator of heart-fate specification. Here, we propose to conduct an in depth analysis of the molecular and cellular mechanisms that control COE regulation and function and heart-fate specification with potential novel implications for cardiovascular development and medicine.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL108643-04
Application #
8701367
Study Section
Development - 1 Study Section (DEV1)
Program Officer
Schramm, Charlene A
Project Start
2011-08-01
Project End
2015-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
New York University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
City
New York
State
NY
Country
United States
Zip Code
10012
Wang, Wei; Racioppi, Claudia; Gravez, Basile et al. (2018) Purification of Fluorescent Labeled Cells from Dissociated Ciona Embryos. Adv Exp Med Biol 1029:101-107
Gandhi, Shashank; Razy-Krajka, Florian; Christiaen, Lionel et al. (2018) CRISPR Knockouts in Ciona Embryos. Adv Exp Med Biol 1029:141-152
Razy-Krajka, Florian; Gravez, Basile; Kaplan, Nicole et al. (2018) An FGF-driven feed-forward circuit patterns the cardiopharyngeal mesoderm in space and time. Elife 7:
Brozovic, Matija; Martin, Cyril; Dantec, Christelle et al. (2016) ANISEED 2015: a digital framework for the comparative developmental biology of ascidians. Nucleic Acids Res 44:D808-18
Anderson, Heather Evans; Christiaen, Lionel (2016) Ciona as a Simple Chordate Model for Heart Development and Regeneration. J Cardiovasc Dev Dis 3:
Lam, Kari Y; Westrick, Zachary M; Müller, Christian L et al. (2016) Fused Regression for Multi-source Gene Regulatory Network Inference. PLoS Comput Biol 12:e1005157
Tolkin, Theadora; Christiaen, Lionel (2016) Rewiring of an ancestral Tbx1/10-Ebf-Mrf network for pharyngeal muscle specification in distinct embryonic lineages. Development 143:3852-3862
Kaplan, Nicole; Razy-Krajka, Florian; Christiaen, Lionel (2015) Regulation and evolution of cardiopharyngeal cell identity and behavior: insights from simple chordates. Curr Opin Genet Dev 32:119-28
Stolfi, Alberto; Sasakura, Yasunori; Chalopin, Domitille et al. (2015) Guidelines for the nomenclature of genetic elements in tunicate genomes. Genesis 53:1-14
Diogo, Rui; Kelly, Robert G; Christiaen, Lionel et al. (2015) A new heart for a new head in vertebrate cardiopharyngeal evolution. Nature 520:466-73

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