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Updated: Apr 12, 2026
Analysis of Cardiomyocyte Development using Immunofluorescence in Embryonic Mouse Heart
Published on: March 26, 2015
Casz1 is required for cardiomyocyte G1-to-S phase progression during mammalian cardiac development
Kerry M Dorr1, Nirav M Amin1, Lauren M Kuchenbrod1
1University of North Carolina McAllister Heart Institute, UNC-Chapel Hill, Chapel Hill, NC 27599-3280, USA Department of Genetics, UNC-Chapel Hill, Chapel Hill, NC 27599-3280, USA.
Abstract:
Organ growth occurs through the integration of external growth signals during the G1 phase of the cell cycle to initiate DNA replication. Although numerous growth factor signals have been shown to be required for the proliferation of cardiomyocytes, genetic studies have only identified a very limited number of transcription factors that act to regulate the entry of cardiomyocytes into S phase. Here, we report that the cardiac para-zinc-finger protein CASZ1 is expressed in murine cardiomyocytes. Genetic fate mapping with an inducible Casz1 allele demonstrates that CASZ1-expressing cells give rise to cardiomyocytes in the first and second heart fields. We show through the generation of a cardiac conditional null mutation that Casz1 is essential for the proliferation of cardiomyocytes in both heart fields and that loss of Casz1 leads to a decrease in cardiomyocyte cell number. We further report that the loss of Casz1 leads to a prolonged or arrested S phase, a decrease in DNA synthesis, an increase in phospho-RB and a concomitant decrease in the cardiac mitotic index. Taken together, these studies establish a role for CASZ1 in mammalian cardiomyocyte cell cycle progression in both the first and second heart fields.
Insights
The cardiac para-zinc-finger protein CASZ1 is crucial for cardiomyocyte proliferation and cell cycle progression. Loss of CASZ1 in mice reduces cardiomyocyte number and impairs DNA synthesis during heart development.
Area of Science:
- Cardiovascular Biology
- Molecular Biology
- Developmental Biology
Background:
- Organ growth relies on cell cycle progression, particularly cardiomyocyte proliferation, regulated by external signals.
- Limited transcription factors are known to control cardiomyocyte entry into S phase.
Purpose of the Study:
- To investigate the role of the cardiac para-zinc-finger protein CASZ1 in cardiomyocyte cell cycle progression.
- To determine if CASZ1 is essential for cardiomyocyte proliferation in the developing heart.
Main Methods:
- Generated genetically modified mice with inducible Casz1 alleles and cardiac conditional null mutations.
- Utilized genetic fate mapping to trace CASZ1-expressing cells.
- Analyzed cardiomyocyte proliferation, cell number, DNA synthesis, and cell cycle markers.
Main Results:
- CASZ1 is expressed in murine cardiomyocytes and its expressing cells contribute to both first and second heart fields.
- Loss of Casz1 significantly reduces cardiomyocyte proliferation and cell number.
- Casz1 deficiency leads to prolonged/arrested S phase, decreased DNA synthesis, increased phospho-RB, and reduced mitotic index.
Conclusions:
- CASZ1 is essential for mammalian cardiomyocyte cell cycle progression.
- CASZ1 plays a critical role in regulating cardiomyocyte proliferation in both heart fields during development.
