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Expression of tumor necrosis factor-alpha (TNF alpha)-cross-reactive proteins during early chick embryo development
1Department of Physiology, University of Alberta, Edmonton, Canada.
Insights
Researchers identified tumor necrosis factor-alpha (TNF alpha)-cross-reactive proteins in early chick embryos. These proteins, detected via antibodies, are widespread and may play a role in programmed cell death and tissue remodeling.
Area of Science:
- Developmental Biology
- Immunology
- Cell Biology
Background:
- Tumor necrosis factor-alpha (TNF alpha) is a key cytokine involved in inflammation and immunity.
- TNF alpha-like proteins have been identified in various cell types, including cytotoxic T-lymphocytes.
- Understanding the role of TNF alpha-related molecules in early embryonic development is crucial.
Purpose of the Study:
- To investigate the expression and distribution of TNF alpha-cross-reactive proteins during early chick embryo development (days 1-6).
- To identify the molecular weight and cellular localization of these proteins.
- To hypothesize the potential functions of these proteins in embryonic development.
Main Methods:
- Utilized polyclonal and monoclonal antibodies against mouse TNF alpha for Western blotting and ultrastructural cytochemistry.
- Analyzed protein expression in chick embryos from day 1 to day 6 (H-H stages 5-29).
- Examined tissue distribution and cellular localization of immunoreactive proteins.
Main Results:
- Identified 50 kDa and 70 kDa proteins with anti-TNF alpha cross-reactivity, and a 120 kDa protein recognized by monoclonal antibodies.
- Confirmed antibody cross-reactivity with chicken tissue via Western blotting.
- Demonstrated widespread tissue distribution of these proteins, with initial expression in mesoderm and endoderm, later appearing in ectoderm, nervous tissue, notochord, myotome, and lens fibers.
Conclusions:
- TNF alpha-cross-reactive proteins are present and widely distributed during early chick embryogenesis.
- These proteins are likely cytosolic or transmembrane TNF alpha-like molecules.
- Their expression patterns suggest a potential role in programmed cell death (apoptosis) and tissue remodeling during the differentiation of key embryonic structures.
Abstract:
We have investigated the expression of tumor necrosis factor-alpha (TNF alpha)-cross-reactive proteins during the early development of the chick embryo from day 1 to day 6 (H-H stages 5-29) using a polyclonal antibody and two monoclonal antibodies to recombinant mouse TNF alpha. We have confirmed the cross-reactivity of the antibodies with chicken tissue in Western blotting studies. Proteins of 50 kDa and 70 kDa, showing anti-TNF alpha cross-reactivity, have been identified during early chick development. In addition, both monoclonal antibodies recognize a 120 kDa protein. These molecules probably represent cytosolic or transmembrane TNF-alpha-like proteins, similar to those previously identified on the surface of cytotoxic T-lymphocytes. We show by ultrastructural cytochemistry that immunoreactivity can be detected at the surfaces of some cells, suggesting that at least some of the antigen is membrane-associated. The proteins are shown to have a widespread tissue distribution during this period of development. Immunoreactivity is first detected in the gastrulating embryo, in the mesoderm and the endoderm. By day 2, expression is confined to the ectoderm and the endoderm, while at day 3 expression appears in the myotome, the notochord, and in nervous tissue. At day 4 the distribution of reactivity is more extensive and includes the notochord, the sclerotome, and the myotome, while the cranial and spinal nerves also become intensely immunoreactive. Also at this stage, neural tube reactivity becomes localized to the marginal neuroepithelial zone, and the lens fibers become positive. This distribution of staining then persists until 6 days of development. We hypothesize that the expression of TNF alpha-cross-reactive proteins in early development could be indicative of a role for them in programmed cell death (apoptosis) during differentiation of the notochord, the lens, and the nervous system, and in tissue remodeling.