Hair follicle bulge cultures yield class III β-tubulin-positive melanoglial cells

Class III β-tubulin (TUBB3)-positive cells from the hair follicle bulge are thought to be neuronal cells derived from a local neural crest stem cell. However, TUBB3 has recently been shown to be expressed in the melanocytic lineage. To evaluate the neural-crest-associated immunophenotype of TUBB3-positive cells from hair follicle bulge explants, we dissected hair follicle bulges out from mouse whisker pads and cultured for 1 month and assessed outgrowing cells by means of immunocytochemistry using the biomarkers TUBB3, nestin, NGFR, SOX9, TYRP1 and laminin. Large amounts of TUBB3-positive cells could be cultured that co-expressed nestin, NGFR, SOX9 and, to a lesser degree, TYRP1, matching a melanoglial phenotype. In addition, a small population of TUBB3-negative but laminin-positive cells was found, which presumably are of glial origin. It can be concluded that cells of melanoglial origin can easily be obtained from hair follicle bulge explants. These cells may be of use in experimental animal or human disease and wound healing models. Notably, the TUBB3-positive cells are of melanoglial rather than neuronal origin

Characterization of the melanocyte lineage in patchwork hair follicles

International audienceMice homozygous for the patchwork (pwk) recessive mutation are salt and pepper: their coat contains a mixture of unpigmented and fully pigmented hairs, but no partially pigmented hairs1. In the matrix of pwk/pwk unpigmented hair follicles, there are no mature melanocyte. This phenotype could be due to: (i) absence of the melanocyte stem cell (MSC) population, (ii) impaired differentiation of MSC into transit amplifying cells (TA cells), (iii) inhibition of TA cells proliferation and/or migration, or (iv) death of melanoblasts within the proliferative compartment. To discriminate between these hypotheses, we used transgenic mice expressing reporter genes for the melanocyte lineage, namely Dct-lacZ and Pax3GFP 2. We validated the Pax3GFP reporter strain by comparing its labelling of melanocyte lineage to Dct-lacZ’s. In pwk/pwk hair follicles, whatever the hair color, MSC and TA cells are present though in reduced number in the bulge and in the transitory portion respectively. In pwk/pwk unpigmented hair follicles, some TA cells reach the bulb region where they remain undifferentiated. By contrast, in the bulb of pwk/pwk pigmented hair follicles, TA cells are more numerous and differentiate into functional melanocytes. To test whether the impaired differentiation in the unpigmented hair follicles is related to the lower number of melanoblasts, we dissected pwk/pwk; Dct-lacZ/Dct-lacZ or pwk/pwk; Pax3GFP/+ and control hair follicles and counted cells of the melanocyte lineage within single hair follicles. Which process (survival, proliferation and/or migration) is deficient in the transit amplifying population is under investigation

Melanocyte precocious differentiation and ectopic localization in Notch conditional loss-of-function mice.

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