44 MARINE INGREDIENTS


Figure 2: Regulatory genes involved in pigment synthesis pathways in the keratinocytes and melanocytes.


involved in regulating melanogenesis: α- MSH (alpha-melanocyte-stimulating hormone) and ACTH (adrenocorticotropic hormone). Exposure to UV rays triggers transcription in both hormones.6


α-MSH


originates from the division of ACTH; it binds to melanocyte receptors (MC1-R) and stimulates melanin synthesis (most specifically, eumelanogenesis) as well as the proliferation of melanocytes.7


stimulated by α-MSH via MITF (melanocyte inducing transcription factor).1


Essential for


initiating melanogenesis, tyrosinase catalyses tyrosine oxidation into dopaquinone, which is a substrate for melanin synthesis (Fig 2). Signalling pathways are activated during


The majority of elements that


regulate skin pigmentation are structural fibrillar components at the very centre of melanocytes. These components are key to melanosome structure and to melanin or enzyme component binding for synthesis. Of all of these enzymes, tyrosinase is the rate- limiting enzyme in melanogenesis. Tyrosinase is synthesised as an inactive precursor that is subsequently activated when melanocytes are


100 90 80 70 60 50 40 30 20 10 0


pigment synthesis, a process that is controlled by the expression of various genes. Multiple genes play primary roles, including activator genes such as POMC, SCTE and inhibitor genes, including CTSL2, AGRP and DKK1 (Fig 2). POMC (proopiomelanocortin) is considered


the activator gene for melanogenesis because it triggers ACTH and α-MSH synthesis (POMC- derived peptides resulting from the division of this protein). More specifically, SCTE (stratum corneum tryptic enzyme, or KLK5) is a pigmentation activator gene that codes for a


n Untreated n CyWhite +117% 200 -37% -46% 100 150 +48% +35%


serine protease enzyme which is strongly expressed in keratinocytes. SCTE activates the PAR2 (protease-activated receptor 2), which helps induce the transfer of melanosomes to keratinocytes.8 Among genes inhibiting melanogenesis


and pigmentation, the CTSL2 (cathepsin V, or cathepsin L2) gene codes for a lysosomal cysteine proteinase involved in melanosome degradation in keratinocytes.9 This gene has helped to demonstrate that the pigmentation of skin colour is inversely proportional to the quantity of CTSL2 expressed in that skin.10


Accordingly, CSTL2


expression is strong in light skin and low in dark skin. The AGRP (Agouti-related neuropeptide) gene codes for the Agouti protein (also known as ASP, Agouti signal protein). That protein is an α-MSH


n Untreated n CyWhite


50


0 POMC SCTE


Figure 3: Expression of POMC and CSTE in reconstituted epidermis models treated or not with CyWhite.


PERSONAL CARE EUROPE AGRP DKK1 CTSL2


Figure 4: Expression of AGRP, DKK1 and CTSL2 in reconstituted epidermis model treated or not with CyWhite.


June 2020


Expression% (compared to control)


Expression% (compared to control)


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