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No / The pro-opiomelanocortin (POMC)-derived peptides, -melanocyte-stimulating hormone, and adrenocorticotropic hormone, are important mediators of human skin pigmentation via action at the melanocortin-1 receptor. Recent data suggests that such a regulatory role also exists for the endogenous opiate, -endorphin (-END). A role for this -END in the regulation of follicular pigmentation, however, has not been determined. This study was designed to examine the involvement of the -END/-opiate receptor system in human follicular melanocyte biology. We employed RT-PCR, and immunohisto/cytochemistry and immunoelectron microscopy using -END and -opiate receptor specific antibodies and a functional role for -END was assessed by direct stimulation with the peptide. This study has demonstrated that human hair follicle melanocytes (HFM) express mRNA for the -opiate receptor and POMC. Furthermore, -END and its high affinity -opiate receptor are expressed at the protein level in glycoprotein100-positive follicular melanocytes and as a function of their anatomic location and differentiation status during the hair growth cycle. Functional studies revealed that -END is a modifier of HFM phenotype via its ability to upregulate melanogenesis, dendricity, and proliferation. These findings suggest a new regulatory role for -END in human HFM biology, providing a new research direction into the fundamental regulation of human hair pigmentation.

Yes / Humans are social animals that communicate disproportionately via potent genetic signals imbued in the skin and hair, including racial, ethnic, health, gender, and age status. For the vast majority of us, age-related hair pigment loss becomes the inescapable signal of our disappearing youth. The hair follicle (HF) pigmentary unit is a wonderful tissue for studying mechanisms generally regulating aging, often before this becomes evident elsewhere in the body. Given that follicular melanocytes (unlike those in the epidermis) are regulated by the hair growth cycle, this cycle is likely to impact the process of aging in the HF pigmentary unit. The formal identification of melanocyte stem cells in the mouse skin has spurred a flurry of reports on the potential involvement of melanocyte stem cell depletion in hair graying (i.e., canities). Caution is recommended, however, against simple extrapolation of murine data to humans. Regardless, hair graying in both species is likely to involve an age-related imbalance in the tissue's oxidative stress handling that will impact not only melanogenesis but also melanocyte stem cell and melanocyte homeostasis and survival. There is some emerging evidence that the HF pigmentary unit may have regenerative potential, even after it has begun to produce white hair fibers. It may therefore be feasible to develop strategies to modulate some aging-associated changes to maintain melanin production for longer.

Hårfollikeln är en struktur som hittas hos alla däggdjur. Hår skyddar kroppen från UV-ljus, medverkar i kroppens värmereglering och har flera kommunikativa funktioner. Hårets varierande färg inom och mellan arter är både en fascinerande och intresseväckande egenskap som länge har studerats som en modell för genetisk nedärvning. I denna litteraturstudie ges en genomgång av hårfollikelns struktur och funktion, genetiken bakom hårets pigmentering samt didaktiska utmaningar i genetikundervisningen. Interaktioner mellan generna MC1R, ASIP (agouti) och POMC förklaras och exemplifieras. Dessutom diskuteras hur fårfollikeln och de pigmentreglerande generna kan användas i gymnasieskolan som ett exempel för komplicerade genetiska interaktioner. / The hair follicle is a structure found in all mammals. Hair protects the body from UV-induced damage, assists the body in its thermoregulation and has several communicative functions. The great variation in hair colour, both within and between species, is a captivating and intriguing trait that has been used as a model for genetic inheritance for a long time. This literature review features the structure and function of the hair follicle, the genetics behind the pigmentation of the hair as well as didactic challenges in teaching genetics. Interactions between the genes MC1R, ASIP (agouti) and POMC is both explained and illustrated. This review also discusses how the hair follicle and the genes regulating pigmentation can be used as an example of intricate genetic interactions in the upper secondary school. / <p>På grund av Covid-19 skedde presentation, opponering och respondering skriftligt på distans.</p>

no / Hair diversity, its style, colour, shape and growth pattern is one of our most defining characteristics. The natural versus temporary style is influenced by what happens to our hair during our lifetime, such as genetic hair loss, sudden hair shedding, greying and pathological hair loss in the various forms of alopecia because of genetics, illness or medication. Despite the size and global value of the hair care market, our knowledge of what controls the innate and within-lifetime characteristics of hair diversity remains poorly understood. In the last decade, drivers of knowledge have moved into the arena of genetics where hair traits are obvious and measurable and genetic polymorphisms are being found that raise valuable questions about the biology of hair growth. The recent discovery that the gene for trichohyalin contributes to hair shape comes as no surprise to the hair biologists who have believed for 100 years that hair shape is linked to the structure and function of the inner root sheath. Further conundrums awaiting elucidation include the polymorphisms in the androgen receptor (AR) described in male pattern alopecia whose location on the X chromosome places this genetic contributor into the female line. The genetics of female hair loss is less clear with polymorphisms in the AR not associated with female pattern hair loss. Lifestyle choices are also implicated in hair diversity. Greying, which also has a strong genetic component, is often suggested to have a lifestyle (stress) influence and hair follicle melanocytes show declining antioxidant protection with age and lowered resistance to stress. It is likely that hair research will undergo a renaissance on the back of the rising information from genetic studies as well as the latest contributions from the field of epigenetics.

no / The biochemistry of hair pigmentation is a complex field involving a plethora of protein and peptide mechanisms. The in loco factory for melanin formation is the hair follicle melanocyte, but it is common knowledge that melanogenesis results from a fine tuned concerted interaction between the cells of the entire dermal papilla in the anagen hair follicle. The key enzyme is tyrosinase to initiate the active pigmentation machinery. Hence, an intricate understanding from transcription of mRNA to enzyme activity, including enzyme kinetics, substrate supply, optimal pH, cAMP signaling, is a must. Moreover, the role of reactive oxygen species on enzyme regulation and functionality needs to be taken into account. So far our knowledge on the entire hair cycle relies on the murine model of the C57BL/6 mouse. Whether this data can be translated into humans still needs to be shown. This article aims to focus on the effect of H2O2-redox homeostasis on hair follicle pigmentation via tyrosinase, its substrate supply and signal transduction as well as the role of methionine sulfoxide repair via methionine sulfoxide reductases A and B (MSRA and B).