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Creatine kinase isozyme expression in embryonic chicken heart
W H Lamers1, W J Geerts, A F Moorman
1Department of Anatomy and Embryology, University of Amsterdam, The Netherlands.
Insights
Creatine kinase M is temporarily found in developing chicken hearts, particularly in areas forming conductive tissue. Creatine kinase B appears early in cells involved in generating heart rhythm.
Area of Science:
- Cardiology
- Developmental Biology
- Biochemistry
Background:
- Creatine kinase (CK) isozymes are crucial for cellular energy homeostasis.
- CK M and CK B subunits form different isozymes with distinct tissue expression patterns.
- Understanding CK isozyme distribution is key to studying cardiac development and function.
Purpose of the Study:
- To investigate the spatial and temporal distribution of creatine kinase isozymes in the developing chicken heart.
- To correlate CK isozyme expression patterns with specific cardiac cell types and developmental regions.
Main Methods:
- Immunohistochemistry was employed to detect CK M and CK B subunit distribution.
- Specific polyclonal antibodies targeting the M subunit were used.
- Expression patterns were analyzed during embryonic development (4-11 days of incubation).
Main Results:
- Creatine kinase M, absent in adult hearts, showed transient expression from 4 to 11 days of incubation.
- M-positive cells were localized in the atrium, interventricular septum, and outflow tract, often near conducting and working myocytes.
- Creatine kinase B was initially found in myocardial cells in the inflow tract, associated with rhythm generation.
Conclusions:
- The transient expression of CK M suggests its role in the development of cardiac conductive tissues.
- The early localization of CK B points to its involvement in the initiation of cardiac rhythm.
- CK isozyme patterns provide insights into the differentiation of cardiac cell lineages during development.
Abstract:
The distribution pattern of creatine kinase (EC 2.7.3.2) isozymes in developing chicken heart was studied by immunohistochemistry. Creatine kinase M, which is absent from adult heart, is transiently expressed between 4 and 11 days of incubation. During that period, numerous muscular cells in the roof and septum of the atrium, in the interventricular septum and on top of the trabeculae cordis and at the rim of the outflow tract stain strongly with a polyclonal antibody that is specific for the M subunit. In the ventricle and outflow tract, the M-positive cells are found mainly subendocardially and in the right half, at the transition of conducting and working myocytes. Creatine kinase B, which is the predominant adult isozyme, is initially expressed to a high concentration in a small group of disperse myocardial cells in upstream part of the inflow tract. When compared to the expression pattern of cardiac myosin heavy chains, the observed creatine kinase expression pattern suggests that M-positive cells are mainly found in areas that participate in the formation of cardiac conductive tissue, whereas B-positive cells are first found in areas that are involved in the generation of cardiac rhythm.