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Facial Transplants in Xenopus laevis Embryos
Published on: March 26, 2014
Xapelin and Xmsr are required for cardiovascular development in Xenopus laevis
Masafumi Inui1, Akimasa Fukui, Yuzuru Ito
1Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.
Insights
Xenopus apelin and its receptor Xmsr are crucial for cardiovascular development, influencing endothelial, hematopoietic, and cardiac cell differentiation. Their roles highlight a potential link between endothelial and cardiac development.
Area of Science:
- Developmental Biology
- Cardiovascular Science
- Molecular Biology
Background:
- Cardiovascular development involves complex interactions between endothelial, hematopoietic, and cardiac systems.
- The precise mechanisms and interrelations governing these developmental processes remain incompletely understood.
Purpose of the Study:
- To investigate the roles of Xenopus apelin (Xapelin) and its receptor homologue, Xmsr, in cardiovascular development.
- To elucidate the molecular pathways and potential interconnections between endothelial, hematopoietic, and cardiac differentiation.
Main Methods:
- Isolation and mRNA localization of Xenopus preproapelin (Xpreproapelin).
- Overexpression studies of Xpreproapelin and morpholino antisense oligonucleotide injection for Xapelin and Xmsr.
- Analysis of key developmental markers including XlFli, SCL, Tie2, alpha-globin, XPOX2, and cTnI.
- Functional rescue experiments using constitutively active G alpha i.
Main Results:
- Xpreproapelin overexpression disrupted endothelial and hematopoietic precursor cell marker expression.
- Xapelin and Xmsr knockdown attenuated the expression of endothelium, erythrocyte, myeloid, and cardiomyocyte markers.
- Knockdown of the endothelial marker XlFli mimicked the cardiac differentiation defects observed with Xapelin and Xmsr knockdown.
- G protein alpha i signaling acts downstream of Xmsr, as evidenced by rescue experiments.
Conclusions:
- Xenopus apelin and Xmsr are essential regulators of cardiovascular development.
- An unexpected link exists between endothelial development and cardiac differentiation.
- G protein alpha i signaling is implicated in the Xmsr-mediated pathway during cardiovascular development.
Abstract:
The cardiovascular development is the elaborate process, and despite the extensive studies, the mechanisms underlying endothelial, hematopoietic, and cardiac developments, as well as the interrelation between these processes, are not fully understood. In this study, we demonstrated that Xenopus apelin and Xmsr play pivotal roles in cardiovascular development. Apelin is a recently identified ligand for an orphan G-protein-coupled receptor APJ and is involved in fluid homeostasis in mammals. Xenopus preproapelin (Xpreproapelin) was isolated and its mRNA localized to the region around the presumptive blood vessels, which are overlapping or adjacent to those expressing Xmsr, the Xenopus homologue of APJ. Overexpression of Xpreproapelin disorganized the expression of the endothelial precursor cell marker XlFli and the hematopoietic precursor cell marker SCL at the neurula, whereas embryos injected with morpholino antisense oligonucleotides for Xapelin and Xmsr displayed attenuated expression of Tie2, alpha-globin, XPOX2, and cTnI, markers of endothelium, erythrocytes, myeloid cells, and cardiomyocytes, respectively. XlFli morpholino had similar effects to Xapelin and Xmsr morpholinos on cardiac differentiation, suggesting an unexpected potential relationship between the endothelium and cardiac differentiation. Forced expression of constitutive active G alpha i rescued the phenotypes of Xmsr morpholino-injected embryos, indicating that the i/o type of G protein alpha subunit acts downstream of Xmsr.
