In situ assessment of statins' effect on autophagic activity in zebrafish larvae cardiomyocytes
Jie Zhang1, Zhi Zuo2, Jianxuan Li3
1Department of Radiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Insights
Researchers developed transgenic zebrafish to monitor cardiomyocyte autophagy in vivo. This tool aids in studying heart disease and screening drugs targeting autophagy, a key process in cardiac health.
Area of Science:
- Cardiovascular Biology
- Cellular Biology
- Genetics
Background:
- Cardiomyocyte survival is crucial for treating heart diseases.
- Autophagy modulation is a promising therapeutic strategy.
- In situ monitoring of cardiomyocyte autophagy is needed for research and drug screening.
Purpose of the Study:
- To generate transgenic zebrafish models for in situ monitoring of cardiomyocyte autophagy.
- To validate the models using autophagy-modulating drugs and statins.
- To investigate the role of autophagy in early heart development.
Main Methods:
- Generated transgenic zebrafish expressing EGFP-map1lc3b or mRFP-EGFP-map1lc3b in cardiomyocytes under the myosin light chain 7 promoter.
- Quantified autophagosome and autolysosome density in response to autophagy modulators and statins.
- Utilized live imaging of intact zebrafish for in situ analysis.
Main Results:
- Transgenic zebrafish models successfully monitored autophagic activity in cardiomyocytes.
- Autophagy inducers and inhibitors demonstrated expected regulatory functions.
- Autophagy is involved in early zebrafish heart development, with increased autophagosomes but not autolysosomes.
- Statins reduced autolysosome density, suggesting regulation of autophagic flux.
Conclusions:
- Novel transgenic zebrafish models enable in situ monitoring of cardiomyocyte autophagy.
- These models are valuable for studying autophagy-related cardiomyopathy and for drug screening.
- The findings highlight autophagy's role in early cardiac development and statin-mediated autophagic flux regulation.
Abstract:
Improving the survival rate of cardiomyocytes is the key point to treat most of the heart diseases, and targeting autophagy is a potential advanced therapeutic approach. Monitoring autophagic activity in cardiomyocytes in situ will be useful for studying autophagy-related heart disease and screening autophagy-modulating drugs. Zebrafish, Danio rerio, has been proven as an animal model for studying heart diseases in situ. Taken the advantage of zebrafish, especially the imaging of intact animals, here we generated two stable transgenic zebrafish lines that specifically expressed EGFP-map1lc3b or mRFP-EGFP-map1lc3b in cardiomyocytes under the promoter of myosin light chain 7. We first used a few known autophagy-modulating drugs to confirm their usefulness. By quantifying the density of autophagosomes and autolysosomes, autophagy inducers and inhibitors showed their regulatory functions, which were consistent with previous studies. With the two lines, we then found a significant increase in the density of autophagosomes but not autolysosomes in zebrafish cardiomyocytes at the early developmental stages, indicating the involvement of autophagy in early heart development. To prove their applicability, we also tested five clinical statins by the two lines. And we found that statins did not change the density of autophagosomes but reduced the density of autolysosomes in cardiomyocytes, implying their regulation in autophagic flux. Our study provides novel animal models for monitoring autophagic activity in cardiomyocytes in situ, which could be used to study autophagy-related cardiomyopathy and drug screening.
