Evaluation of the potential role of Ca²⁺ signaling in heart looping in zebrafish embryos, and development of a 3D multi-parameter method to quantify heart looping and heart volumes

Abstract

In spite of recent medical advancements, heart disease remains a leading cause of death worldwide. Some congenital cardiac malformations can result from heart looping defects. The heart looping is a crucial process for ensuring that the future heart chambers are aligned properly to ensure the correct function of the heart. The zebrafish has become a favored vertebrate model for studying cardiac development and disease. However, there is a lack of standardised methodology to quantitatively characterize the heart looping. One aim of this study is to provide a standardized method to quantify the heart looping degree using the zebrafish model. My method relies on access to a light sheet microscope, and 3D analysis software, and it provides various parameters to quantify the heart looping. With this approach, I can compare these parameters on any heart phenotypes. Furthermore, while the requirement for Ca²⁺ during normal heart function is well known, more recent evidence suggests that Ca²⁺ might also play a key role in heart morphogenesis. Thus, having a better understanding of the role of Ca²⁺ signaling in normal heart development might help identify novel therapies for acquired heart diseases, and indicate possible therapeutic options for pharmacological/genetic intervention to promote heart repair and regeneration. My data show that the introduction of the Ca²⁺ chelator, BAPTA-4K, or the treatment of zebrafish with various Ca²⁺ channel inhibitors during the heart tube formation and the heart looping affect the looping process with the observation of abnormal heart phenotypes, including misalignments of the ventricle and atrium, a decrease in the volume of the heart chambers, and failure in heart looping. My results suggest that Ca²⁺ signaling, potentially through the IP₃Rs actions, might be important for heart looping and the generation of the heart chamber volume, and thus the overall morphology of the heart.

Date of Award	2020
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	King Lau CHOW (Supervisor)