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Embryonic RNA expression patterns of the c-kit receptor and its cognate ligand suggest multiple functional roles in
E Keshet1, S D Lyman, D E Williams
1Mammalian Genetics Laboratory, ABL-Basic Research Program, NCI-FCRDC, Frederick, MD 21702-1201.
Abstract:
Mutations at the dominant white spotting (W) and Steel (Sl) loci in mouse exert deleterious effects on three migratory cell lineages (primordial germ cells, melanocytes and hematopoietic stem cells) resulting in loss of pigmentation, reduced fertility and anemia. The W locus encodes the c-kit protein tyrosine kinase (TK) receptor. More recently, the Sl locus has been shown to encode a ligand for c-kit, which is variously known as mast cell growth factor (MGF), stem cell growth factor and c-kit ligand. Here we report an in situ hybridization analysis comparing the expression profiles of MGF and c-kit transcripts during mouse embryogenesis. The data are consistent with the c-kit receptor-ligand complex providing a homing mechanism during stem cell migration in early development and in stem cell proliferation, differentiation, or survival in late development. In the nervous system, an unexpected and complex pattern of expression is uncovered that suggests involvement of the W and Sl gene products in the organization of the neural tube and brain.
Insights
Mutations in the dominant white spotting (W) and Steel (Sl) genes impact cell development. The W and Sl gene products, c-kit and its ligand, are crucial for cell migration and neural organization.
Area of Science:
- Developmental Biology
- Genetics
- Cell Biology
Background:
- The dominant white spotting (W) and Steel (Sl) loci in mice are associated with defects in primordial germ cells, melanocytes, and hematopoietic stem cells.
- The W locus encodes the c-kit protein tyrosine kinase (TK) receptor, while the Sl locus encodes its ligand, known as mast cell growth factor (MGF).
Purpose of the Study:
- To compare the expression profiles of MGF and c-kit transcripts during mouse embryogenesis using in situ hybridization.
- To investigate the role of the c-kit receptor-ligand complex in early and late developmental processes.
Main Methods:
- In situ hybridization was employed to analyze the spatiotemporal expression patterns of MGF and c-kit transcripts in mouse embryos.
- Expression profiles were compared across different developmental stages and tissues.
Main Results:
- The study revealed distinct and dynamic expression patterns for both MGF and c-kit during mouse embryogenesis.
- Coordinated expression suggests the c-kit receptor-ligand complex is involved in stem cell migration, proliferation, differentiation, and survival.
- An unexpected complex expression pattern was observed in the nervous system, indicating a role in neural tube and brain organization.
Conclusions:
- The c-kit receptor-ligand interaction is essential for the homing and maintenance of critical cell lineages during development.
- The W and Sl gene products play a significant role in the organization of the developing nervous system.
- These findings highlight the fundamental importance of the c-kit signaling pathway in mammalian embryogenesis.