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The distribution and characterization of HNK-1 antigens in the developing avian heart
T M Luider1, N Bravenboer, C Meijers
1Department of Paediatric Surgery, Sophia Children Hospital, Erasmus University, Rotterdam, The Netherlands.
Insights
The HNK-1 antibody marks developing heart structures, revealing expression in regions before neural crest cell colonization. This indicates HNK-1 immunoreactivity is not solely linked to neural crest derivatives in the early avian heart.
Area of Science:
- Developmental biology
- Immunohistochemistry
- Cardiovascular research
Background:
- The heart develops from splanchnic mesoderm and neural crest cells.
- HNK-1 antibody is a marker for neural crest cells but also binds to non-neural crest structures.
- Investigating HNK-1 expression timing in the developing heart is crucial for understanding cell origins.
Purpose of the Study:
- To determine HNK-1 antigen expression patterns in the developing avian heart.
- To compare HNK-1 immunoreactivity with neural crest cell colonization sites.
- To ascertain if HNK-1 positive structures exist before neural crest cell arrival.
Main Methods:
- Immunohistochemistry on developing avian heart sections.
- Western blot analysis of HNK-1 antigen expression.
- Comparison with literature data on neural crest cell localization in chick/quail chimeras.
Main Results:
- HNK-1 immunoreactivity was found in neural crest-derived structures like the outflow tract and endocardial cushions.
- HNK-1 was also present in non-neural crest derived regions, including the sinus venosus, endocardium, and myocardium.
- Expression was prominent in dynamic areas: valves, outflow tract cushion, conduction system, and cardiac autonomic nervous system.
Conclusions:
- HNK-1 immunoreactivity does not exclusively indicate neural crest cell presence or derivatives.
- Outflow tract and atrioventricular endocardial cushions show HNK-1 positivity before expected neural crest cell entry.
- Observed spatio-temporal HNK-1 patterns correlate with various HNK-1 antigens, some of which are stage-dependent.
Abstract:
The heart originates from splanchnic mesoderm and to a lesser extent from neural crest cells. The HNK-1 monoclonal antibody is a marker for early migrating neural crest cells, but reacts also with structures which are not derived from the neural crest. We investigated whether heart structures are HNK-1 positive before neural crest cells colonize these target tissues. To that end, we determined the HNK-1 antigen expression in the developing avian heart on immunohistochemical sections and on Western blots. The HNK-1 immunoreactivity in the developing chick heart is compared with data from literature on the localization of neural crest cells in chick/quail chimeras. Structures with neural crest contribution, including parts of the early outflow tract and the related endocardial cushions, the primordia of the semilunar valve leaflets and the aorticopulmonary septum were HNK-1 positive. Furthermore, other structures were HNK-1 positive, such as the atrioventricular cushions, the wall of the sinus venosus at stage HH 15 through 21, parts of the endocardium at E3, parts of the myocardium at E6, and the extracellular matrix in the myocardial base of the semilunar valves at E14. HNK-1 expression was particularly observed in morphologically dynamic regions such as the developing valves, the outflow tract cushion, the developing conduction system and the autonomic nervous system of the heart. We observed that atrioventricular endocardial cushions are HNK-1 positive. We conclude that: a HNK-1 immunoreactivity does not always coincide with the presence of neural crest cells or their derivatives; (2) the outflow tract cushions and atrioventricular endocardial cushions are HNK-1 positive before neural crest cells are expected (stage HH 19) to enter the endocardial cushions of the outflow tract; (3) the observed spatio-temporal HNK-1 patterns observed in the developing heart correspond with various HNK-1 antigens. Apart from a constant pattern of HNK-1 antigens during development, stage-dependent HNK-1 antigens were also found.