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Published on: June 3, 2018
Hand2 ensures an appropriate environment for cardiac fusion by limiting Fibronectin function
Zayra V Garavito-Aguilar1, Heather E Riley, Deborah Yelon
1Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Development (Cambridge, England)
|August 21, 2010
Summary
The Hand2 transcription factor is crucial for heart formation. This study identifies fibronectin 1 as a key downstream target, revealing how Hand2 regulates cardiomyocyte movement for proper cardiac fusion.
Area of Science:
- Developmental biology
- Cardiovascular research
- Zebrafish models
Background:
- Heart development involves the precise fusion of bilateral cardiomyocyte populations at the embryonic midline.
- The basic helix-loop-helix (bHLH) transcription factor Hand2 is known to be essential for this cardiac fusion process.
- However, the specific downstream effector genes regulated by Hand2 that mediate this function remain unidentified.
Purpose of the Study:
- To identify downstream effector genes of the Hand2 pathway involved in cardiac morphogenesis.
- To elucidate the mechanism by which Hand2 regulates cardiomyocyte movement and fusion.
- To investigate the role of fibronectin 1 (fn1) in Hand2-mediated cardiac fusion in zebrafish.
Main Methods:
- Utilized zebrafish as a model organism for studying cardiac development.
- Performed mosaic analysis to assess the non-autonomous role of Hand2 in cardiomyocyte migration.
- Analyzed gene expression profiles to identify differentially expressed genes in hand2 mutant embryos.
- Investigated the effect of fn1 knockdown on cardiac fusion in hand2 mutant zebrafish.
Main Results:
- Demonstrated a non-autonomous role for Hand2 in regulating cardiomyocyte movement.
- Identified fibronectin 1 (fn1) as significantly upregulated in hand2 mutant embryos and downregulated upon Hand2 overexpression.
- Showed that reducing fn1 function rescues cardiac fusion defects in hand2 mutants, improving tissue architecture.
- Observed rescue of cardiac fusion without significant alterations in apicobasal polarity.
Conclusions:
- The Hand2 pathway establishes a favorable environment for cardiac fusion by negatively modulating fibronectin 1 levels.
- This study reveals fibronectin 1 as a novel downstream component mediating Hand2's function in cardiac morphogenesis.
- Provides a new model where a tissue actively creates its own favorable environment for development through gene regulation.
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