Related Experiment Videos
Developmental analysis of tropomyosin gene expression in embryonic stem cells and mouse embryos
M Muthuchamy1, L Pajak, P Howles
1Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Ohio 45267-0524.
Abstract:
Tropomyosins (TMs) comprise a family of actin-binding proteins which play an important role in the regulation of contractility in muscle (cardiac, skeletal, and smooth) and nonmuscle cells. Although they are present in all cells, different isoforms are characteristic of specific cell types. In vertebrates, there are four different TM genes (alpha-TM, beta-TM, TM30, and TM4), three of which generate alternatively spliced isoforms. This study defines the expression patterns of these isoforms during murine embryogenesis, using both in vivo and in vitro conditions. The embryonic stem cell culture system, which has been shown to mimic different stages of mouse embryonic development, including the differentiation of primitive organ systems such as the myocardium, is used for our in vitro analysis. Our results demonstrate that several TM isoforms are expressed in specific developmental patterns, often correlated with the differentiation of particular tissues or organs. Surprisingly, other TMs, such as the striated muscle beta-TM and smooth muscle alpha-TM, are expressed constitutively. This study also demonstrates that there is an excellent correlation between the expression patterns of the TM isoforms observed in developing embryonic stem cells and mouse embryos. In addition, a quantitative molecular analysis of TM isoforms was conducted in embryonic, neonatal, and adult cardiac tissue. Our results show for the first time that the alpha- and beta-TM striated muscle transcripts are present in the earliest functional stages of the heart, and these TM isoforms are identical to those present throughout cardiac development.
Insights
Tropomyosin (TM) isoforms are key for muscle and nonmuscle cell function. This study maps TM isoform expression during mouse development, finding specific patterns correlating with tissue differentiation and constitutive expression in adult tissues.
Area of Science:
- Molecular Biology
- Developmental Biology
- Cell Biology
Background:
- Tropomyosins (TMs) are actin-binding proteins crucial for muscle and nonmuscle cell contractility.
- Different TM isoforms are cell-type specific, arising from four vertebrate genes, three with alternative splicing.
- Understanding TM isoform expression during development is vital for comprehending tissue differentiation.
Purpose of the Study:
- To define the expression patterns of tropomyosin isoforms during murine embryogenesis.
- To correlate TM isoform expression with specific tissue and organ differentiation in vivo and in vitro.
- To quantitatively analyze TM isoforms in cardiac tissue throughout development.
Main Methods:
- Utilized a murine embryonic stem cell culture system to mimic in vitro development.
- Performed in vivo analysis of TM isoform expression in mouse embryos.
- Conducted quantitative molecular analysis of TM isoforms in embryonic, neonatal, and adult cardiac tissue.
Main Results:
- Several TM isoforms exhibit specific developmental expression patterns linked to tissue differentiation.
- Striated muscle beta-TM and smooth muscle alpha-TM are expressed constitutively.
- Expression patterns in embryonic stem cells closely correlate with those in developing mouse embryos.
- Alpha- and beta-TM striated muscle transcripts are present from the earliest functional heart stages and remain consistent throughout cardiac development.
Conclusions:
- Tropomyosin isoform expression is dynamically regulated during murine embryogenesis, often correlating with specific tissue differentiation.
- Constitutive expression of certain TM isoforms, like striated muscle beta-TM and smooth muscle alpha-TM, is observed.
- The study establishes a strong correlation between in vitro embryonic stem cell models and in vivo embryonic development for TM isoform expression.
- Alpha- and beta-TM striated muscle transcripts are foundational to cardiac development, present from the earliest stages.