Figure 9.

Expression of CRF, CRFR-1, and CRFR-2 in hair follicle melanocytes and the effect of CRF on follicular melanocytes. a, Human hair follicles express CRF and cognate receptors CRFR-1 (CRF1) and CRFR-2 (CRF2) (red fluorescence). These proteins were also detected in a subpopulation of melanocytes (yellow) located in the proximal/peripheral matrix region and in the outer root sheath (see arrowheads in enlargements of insets) but apparently were down-regulated in the melanogenic zone of anagen VI hair follicles. Cytoplasmic expression of CRF and its receptors was present in hair bulb keratinocytes and less so in dermal papilla cells (FP). b, CRF (10⁻⁸ m) stimulated dendricity in cultured hair follicle melanocytes. Cell dendricity was assessed by counting cells with three or more dendrites before and after stimulation of cells. c, CRF (10⁻⁷ m) stimulated melanogenesis in hair follicle melanocytes in culture. CRF modulated the expression and activity of melanogenic enzymes in hair follicle melanocytes in culture, including: d, tyrosinase protein expression and activity (dopa oxidase); e, TRP-1; and f, DCT (TRP-2). Lane 1, Molecular weight markers; lane 2, CRF 10⁻⁷ m; lane 3, unstimulated control; lane 4, negative control. [Individual panels were reproduced from S. Kauser et al: Modulation of the human hair follicle pigmentary unit by corticotropin-releasing hormone and urocortin peptides. FASEB J. 2006;20:882–895 (213), with permission. © Federation of American Societies for Experimental Biology.]