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Characterization of melanocyte development defects in Waardenburg syndrome

Immunostaining of melanocytes from a mouse hair follicle. The nuclei of the cells are stained blue. All melanocytes express c-Kit growth factor (in red) but only mature melanocytes produce melanin, which causes hair and skin staining, thanks to the enzyme dopachrome tautomerase (in green). The loss of this mature melanocyte population may be responsible for the partial depigmentation of skin and hair in the type 4 Waardenburg syndrome.

Project description

Waardenburg syndrome is characterized by skin and hair pigmentation defects, as well as by inner ear dysfunction affecting hearing and/or balance. These anomalies are believed to be due to defective development of neural crest-derived melanocytes (pigment cells). In the inner ear, we previously reported using the Spot mouse model (which overexpresses Nr2f1 in neural crest cells) that balance problems are due to a specific lack of melanocytes in the vestibule. In the skin, preliminary results show that melanocytes are not properly located along the epidermis in Spot embryos. As melanocytes can be derived from two pathways, either directly from neural crest cells or indirectly from a Schwann cell intermediate, the question is which of these pathways is affected in Spot animals. This is currently addressed using a cell lineage tracing approach based on the Schwann cell specific transgene Plp1-CreERT2 and the R26R-YFP Cre activity reporter. In combination with specific labeling of melanoblasts/melanocytes, it will enable to determine if the observed defects in the skin and inner ear are related to the failure of one or both of the two sources of melanocytes. Then, via time-lapse imaging and marker analyses, we will determine whether these defects are due to a problem of migration, differentiation, proliferation or survival of melanocyte precursors. In the end, this study will significantly increase our understanding of Waardenburg syndrome.

Research team

Name: Grégoire Bonnamour,M.Sc.
Supervisor: Nicolas Pilon (UQAM)
Laureate: Doctoral scholarship 2018

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