Targeting Small Non-coding RNAs to Diminish the Epigenetic Ravages of Aged Skin
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Presented by: Paul Lawrence
Epigenetics represents one of the most exciting new areas of research within the cosmetic care community. Through measured application of epigenetic modulators, cosmetic care scientists can reverse some of the natural aging processes and restore skin features to those of a younger individual. Indeed, non-coding RNA molecules (ncRNAs) are the effectors of one epigenetic mechanism known as post-transcriptional gene silencing (PTGS) or RNA interference (RNAi). Here, short RNA molecules called microRNAs (miRNAs or miRs) are able to intercept messenger RNAs (mRNAs) of expressed genes and prevent their interaction with ribosomes, thus halting protein synthesis for that particular gene.
Many research groups have corroborated the relationship between miRNAs and skin health via miRNA profiling studies. In these evaluations, skin cells and tissues treated with various skin care products have had their cellular RNA harvested and examined by quantitative polymerase chain reaction (qPCR) for alterations in the homeostatic levels of certain endogenous miRNAs. Indeed, we conducted such a test on populations of human keratinocytes treated with two different skin care products. One material induced a reduction in six different miRNAs, while the other increased the cellular levels of only one miRNA.
Cosmetic care scientists can toggle the switches of PTGS either by applying “mimics” of naturally occurring miRNAs (a process referred to as “microRNA replacement therapy”) to augment the down-regulation in expression of a certain gene. Alternatively, application of so-called “antagomiRs” that irreversibly bind and sequester naturally occurring miRNAs promote up-regulation of expression of genes that miRNA would have targeted. The remaining hurdle to be surmounted for the mainstream deployment of this technology remains the development of a suitable delivery vehicle for these ncRNAs.
To that end, a proprietary formulation called MIRNAC™ was examined for its capacity to effectively deliver mimics and antagomiRs into skin cells. Multiple proof-of-concept experiments were performed that successfully demonstrated mixtures of MIRNAC™ with either mimics or antagomiRs could attenuate gene expression in a manner favorable to skin health and appearance. First, the modulation of tyrosinase levels, the key enzyme in the melanin synthesis pathway, was tackled employing mimics of miR-218-5p, which sequesters mRNAs for tyrosinase expression. Complexes of these mimics with MIRNAC™ were successfully delivered to normal melanocytes, melanocyte-derived cell lines, and a three-dimensional melanocyte-infused model of the skin (MelanoDerm) to induce skin brightening. This effect was confirmed by visual examination of harvested cells and tissues and molecularly via Western blot analysis.
In contrast, antagomiRs to miR-29a-3p were applied to human fibroblasts in a second series of experiments. Endogenous miR-29a-3p levels increase in our skin cells as we age, which knockdown the expression of many important fiber proteins including collagen, elastin, and fibrillin. As such, this miRNA is occasionally referred to as the “wrinkle miRNA”. The introduction of miR-29a-3p antagomiRs mixed with MIRNAC™ into human fibroblasts was attempted. Downstream analyses confirmed that this triggered an increase in the production of multiple fiber proteins including collagen, which was visualized by immunofluorescence microscopy and also by Western blot analysis.
These two studies complemented by miRNA profiling highlight the utility of PTGS as an effective means to improve skin health and appearance. The results also confirm that MIRNAC™ was capable of transporting mimics and antagomiRs into desired cell populations. Moreover, a series of MIRNAC™ dilutions elucidated the ideal quantity of the reagent to deliver the greatest impact. Topical application of such ncRNA complexes is likely to have a significant impact on the future of cosmetic care.
Many research groups have corroborated the relationship between miRNAs and skin health via miRNA profiling studies. In these evaluations, skin cells and tissues treated with various skin care products have had their cellular RNA harvested and examined by quantitative polymerase chain reaction (qPCR) for alterations in the homeostatic levels of certain endogenous miRNAs. Indeed, we conducted such a test on populations of human keratinocytes treated with two different skin care products. One material induced a reduction in six different miRNAs, while the other increased the cellular levels of only one miRNA.
Cosmetic care scientists can toggle the switches of PTGS either by applying “mimics” of naturally occurring miRNAs (a process referred to as “microRNA replacement therapy”) to augment the down-regulation in expression of a certain gene. Alternatively, application of so-called “antagomiRs” that irreversibly bind and sequester naturally occurring miRNAs promote up-regulation of expression of genes that miRNA would have targeted. The remaining hurdle to be surmounted for the mainstream deployment of this technology remains the development of a suitable delivery vehicle for these ncRNAs.
To that end, a proprietary formulation called MIRNAC™ was examined for its capacity to effectively deliver mimics and antagomiRs into skin cells. Multiple proof-of-concept experiments were performed that successfully demonstrated mixtures of MIRNAC™ with either mimics or antagomiRs could attenuate gene expression in a manner favorable to skin health and appearance. First, the modulation of tyrosinase levels, the key enzyme in the melanin synthesis pathway, was tackled employing mimics of miR-218-5p, which sequesters mRNAs for tyrosinase expression. Complexes of these mimics with MIRNAC™ were successfully delivered to normal melanocytes, melanocyte-derived cell lines, and a three-dimensional melanocyte-infused model of the skin (MelanoDerm) to induce skin brightening. This effect was confirmed by visual examination of harvested cells and tissues and molecularly via Western blot analysis.
In contrast, antagomiRs to miR-29a-3p were applied to human fibroblasts in a second series of experiments. Endogenous miR-29a-3p levels increase in our skin cells as we age, which knockdown the expression of many important fiber proteins including collagen, elastin, and fibrillin. As such, this miRNA is occasionally referred to as the “wrinkle miRNA”. The introduction of miR-29a-3p antagomiRs mixed with MIRNAC™ into human fibroblasts was attempted. Downstream analyses confirmed that this triggered an increase in the production of multiple fiber proteins including collagen, which was visualized by immunofluorescence microscopy and also by Western blot analysis.
These two studies complemented by miRNA profiling highlight the utility of PTGS as an effective means to improve skin health and appearance. The results also confirm that MIRNAC™ was capable of transporting mimics and antagomiRs into desired cell populations. Moreover, a series of MIRNAC™ dilutions elucidated the ideal quantity of the reagent to deliver the greatest impact. Topical application of such ncRNA complexes is likely to have a significant impact on the future of cosmetic care.