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Steel factor directs melanocyte development in vitro through selective regulation of the number of c-kit+ progenitors
K Reid1, S Nishikawa, P F Bartlett
1Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Abstract:
Studies of mice containing mutations in the genes for a receptor tyrosine kinase, c-kit, or its cognate ligand, Steel factor (SLF), establish that this signaling pathway is required for the development of melanocytes from their precursors in the embryonic neural crest (NC). In order to define the mechanism of this requirement, we have labeled cells expressing c-kit with an anti-c-kit antibody (ACK2) and studied the action of SLF on these cells in cultures of murine trunk NC. c-kit positive (c-kit+) cells first appeared after 2 days in culture and were morphologically indistinguishable from other NC cells. These cells subsequently expressed tyrosinase-related protein, an early marker for the melanocyte lineage, and became pigmented in the presence of a phorbol ester. Further, elimination of the c-kit+ population, by incubating the cultures in ACK2, resulted in the ablation of the melanocyte population, but had no effect on the generation of other neural crest derivatives. These data indicate that c-kit+ cells arising from the neural crest are melanocyte progenitors. The addition of SLF to these cultures stimulated an increase in the number of c-kit+ cells, and further studies indicated that SLF acts as both a survival and a proliferative factor for c-kit+ cells. These findings provide a mechanism of regulation of melanocyte development, whereby c-kit is exclusively expressed by melanocyte progenitors within the neural crest precursor population, and subsequent survival and proliferation of these progenitors is regulated by SLF.
Insights
The c-kit signaling pathway is crucial for melanocyte development from neural crest precursors. Steel factor (SLF) promotes the survival and proliferation of c-kit positive melanocyte progenitors.
Area of Science:
- Developmental Biology
- Cell Signaling
- Molecular Biology
Background:
- The c-kit receptor tyrosine kinase and its ligand, Steel factor (SLF), are essential for melanocyte development.
- The precise role of this signaling pathway in melanocyte precursor development from the embryonic neural crest (NC) requires further elucidation.
Purpose of the Study:
- To define the mechanism by which the c-kit/SLF signaling pathway regulates melanocyte development from neural crest precursors.
- To identify and characterize melanocyte progenitor cells within the murine trunk neural crest population.
Main Methods:
- Labeling of c-kit expressing cells using the anti-c-kit antibody (ACK2).
- Culture of murine trunk neural crest cells to observe c-kit positive cell development and differentiation.
- Treatment with Steel factor (SLF) to assess its effect on c-kit positive cell populations.
- Elimination of c-kit positive cells using ACK2 to determine their role in melanocyte formation.
Main Results:
- c-kit positive (c-kit+) cells emerged in culture and expressed melanocyte lineage markers, becoming pigmented.
- Elimination of c-kit+ cells abolished melanocyte generation but did not affect other neural crest derivatives.
- SLF addition increased the number of c-kit+ cells, acting as both a survival and proliferative factor.
Conclusions:
- c-kit+ cells derived from the neural crest are specific melanocyte progenitors.
- The c-kit/SLF pathway exclusively regulates the survival and proliferation of melanocyte progenitors within the neural crest population, thereby controlling melanocyte development.