Related Experiment Videos
Melanocyte development in vivo and in neural crest cell cultures: crucial dependence on the Mitf
K Opdecamp1, A Nakayama, M T Nguyen
1Laboratory of Developmental Neurogenetics, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
The more than 20 different Mitf mutations in the mouse are all associated with deficiencies in neural crest-derived melanocytes that range from minor functional disturbances with some alleles to complete absence of mature melanocytes with others. In the trunk region of wild-type embryos, Mitf-expressing cells that coexpressed the melanoblast marker Dct and the tyrosine kinase receptor Kit were found in the dorsolateral neural crest migration pathway. In contrast, in embryos homozygous for an Mitf allele encoding a non-functional Mitf protein, Mitf-expressing cells were extremely rare, no Dct expression was ever found, and the number of Kit-expressing cells was much reduced. Wild-type neural crest cell cultures rapidly gave rise to cells that expressed Mitf and coexpressed Kit and Dct. With time in culture, Kit expression was increased, and pigmented, dendritic cells developed. Addition of the Kit ligand Mgf or endothelin 3 or a combination of these factors all rapidly increased the number of Dct-positive cells. Cultures from Mitf mutant embryos initially displayed Mitf-positive cells similar in numbers and Kit-expression as did wild-type cultures. However, Kit expression did not increase with time in culture and the mutant cells never responded to Mgf or endothelin 3, did not express Dct, and never showed pigment. In fact, even Mitf expression was rapidly lost. The results suggest that Mitf first plays a role in promoting the transition of precursor cells to melanoblasts and subsequently, by influencing Kit expression, melanoblast survival.
Insights
Microphthalmia-associated transcription factor (Mitf) is crucial for melanocyte development. Mutations in Mitf disrupt neural crest cell differentiation into melanoblasts and affect melanoblast survival.
Area of Science:
- Developmental biology
- Cell biology
- Genetics
Background:
- Over 20 mouse Mitf mutations cause neural crest-derived melanocyte deficiencies.
- Mitf is essential for melanocyte development, impacting cell function and survival.
Purpose of the Study:
- To investigate the role of Mitf in melanoblast development and survival.
- To understand the molecular mechanisms by which Mitf influences melanocyte precursor cells.
Main Methods:
- Analysis of Mitf expression and cell markers (Dct, Kit) in wild-type and Mitf mutant mouse embryos.
- In vitro culture of neural crest cells from wild-type and mutant embryos.
- Treatment with growth factors (Mgf, endothelin 3) to assess cellular responses.
Main Results:
- Mitf-expressing cells co-expressing melanoblast markers were found in wild-type embryos.
- Mitf mutant embryos showed rare Mitf-expressing cells, absent Dct expression, and reduced Kit expression.
- Mutant neural crest cultures failed to upregulate Kit, respond to growth factors, express Dct, or produce pigment.
Conclusions:
- Mitf is required for the initial transition of precursor cells to melanoblasts.
- Mitf influences melanoblast survival, partly through regulating Kit expression.