Human skin responses to UV radiation: pigment in the upper epidermis protects against DNA damage in the lower epidermis and facilitates apoptosis

Yamaguchi, Yuji; Takahashi, Kazutaka; Zmudzka, Barbara Z.; Kornhauser, A.; Miller, Sharon A.; Tadokoro, Taketsugu; Berens, Werner; Beer, Janusz Z.; Hearing, Vincent J.

doi:10.1096/fj.06-5725fje

Cited by 180 publications

(178 citation statements)

References 41 publications

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“…Cells were then incubated with primary antibodies overnight at 4°C, followed by incubation with Texas Red anti-rabbit or fluorescein isothiocyanate streptavidin for polyclonal and monoclonal antibodies, respectively (25). Human skin specimens embedded in paraffin were processed as described previously (26). Fluorescence signals were classified according to whether they showed green, red, or yellow fluorescence, the latter being indicative of colocalization of the red and green fluorescence signals.…”

Section: Methodsmentioning

confidence: 99%

Sialylated Core 1 O-Glycans Influence the Sorting of Pmel17/gp100 and Determine Its Capacity to Form Fibrils

Valencia

Rouzaud

Julien

et al. 2007

Journal of Biological Chemistry

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Pmel17 is a melanocyte/melanoma-specific protein that is essential for the maturation of melanosomes to form mature, fibrillar, and pigmented organelles. Recently, we reported that the less glycosylated form of Pmel17 (termed iPmel17) is sorted via the plasma membrane in a manner distinct from mature Pmel17 (termed mPmel17), which is sorted directly to melanosomes. To clarify the mechanism(s) underlying the distinct processing and sorting of Pmel17, we generated a highly specific antibody (termed ␣PEP25h) against an epitope within the repeat domain of Pmel17 that is sensitive to changes in O-glycosylation. ␣PEP25h recognizes only iPmel17 and allows analysis of the processing and sorting of iPmel17 when compared with ␣PEP13h, an antibody that recognizes both iPmel17 and mPmel17. Our novel findings using ␣PEP25h demonstrate that iPmel17 differs from mPmel17 not only in its sensitivity to endoglycosidase H, but also in the content of core 1 O-glycans modified with sialic acid. This evidence reveals that iPmel17 is glycosylated differently in the Golgi and that it is sorted through the secretory pathway. Analysis of Pmel17 processing in glycosylation-deficient mutant cells reveals that Pmel17 lacking the correct addition of sialic acid and galactose loses the ability to form fibrils. Furthermore, we show that addition of sialic acid affects the stability and sorting of Pmel17 and reduces pigmentation. Alterations in sialyltransferase activity and substrates differ between normal and transformed melanocytes and may represent a critical change during malignant transformation.The human PMEL17 gene encodes two type I integral membrane proteins that are translated from alternatively spliced mRNAs. Those two proteins, known as Pmel17 and gp100, differ as to whether they include a 7-amino acid motif in the membrane proximal region of the luminal domain (1-3). Pmel17 is critical to the formation of an internal fibrillar matrix within stage II melanosomes that is essential to the maturation of that organelle and the subsequent synthesis and deposition of melanin within it. Pmel17 is synthesized as a 68.6-kDa protein, as deduced from the cloned cDNA (2). It is rapidly and quantitatively glycosylated to an "immature" ϳ95-kDa form (termed iPmel17), but only a limited amount is further processed to a "mature" ϳ115-kDa form (termed mPmel17), due at least in part to N-glycosylation at five possible sites (4). mPmel17 can then be cleaved by a furin-like proprotein convertase that generates two fragments, one small fragment (cPmel17, ϳ26 kDa) containing the transmembrane (TM) 3 and the C-terminal domains, and the other larger fragment contains the N-terminal region (5). Those fragments can remain bound to each other by S-S bonds (5, 6). However, the iPmel17 formed remains fully endoglycosidase H (EndoH)-sensitive (4) and is significantly more stable over time than either of the other forms of Pmel17 (mPmel17 and cPmel17) (5).N-Linked core glycosylation begins in the ER and is essential for the function, stability, folding, intrace...

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Section: Methodsmentioning

confidence: 99%

Sialylated Core 1 O-Glycans Influence the Sorting of Pmel17/gp100 and Determine Its Capacity to Form Fibrils

Valencia

Rouzaud

Julien

et al. 2007

Journal of Biological Chemistry

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“…5,6,[30][31][32][33] These findings complete and confirm previous data obtained using skin colour classification based on ethnic origin or racial criteria. 34 They also emphasize that more pigmented melanocytes from intermediate and tan skin types may be targeted by UVR.…”

Section: Dna Damage In Melanocytesmentioning

confidence: 99%

Variations in skin colour and the biological consequences of ultraviolet radiation exposure

2013

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SummaryHarmful consequences of sun exposure range from sunburn, photoageing and pigmentary disorders to skin cancer. The incidence and extent of these detrimental effects are largely due to the degree of constitutive pigmentation of the skin. The latter can be objectively classified according to the individual typology angle (°ITA) based on colorimetric parameters. The physiological relevance of the ITA colorimetric classification was assessed in 3500 women living in various geographical areas. Furthermore, in order to understand the relationship between constitutive pigmentation and ultraviolet radiation (UVR) sensitivity, we worked on ex vivo human skin samples of different colour exposed to increasing UVR doses. For each sample we defined the biologically efficient dose (BED), based on the induction of sunburn cells, and analysed UVR-induced DNA damage (cyclobutane thymine dimers, CPD). We found a significant correlation between ITA and BED. We also found a correlation between ITA and DNA damage. As the epidermal basal layer also hosts melanocytes and in order to analyse the relationship between skin colour and DNA damage occurring specifically within this cell type, we performed double staining for CPD and tyrosinase-related protein (TRP) 1, a key enzyme in melanin synthesis. We found that DNA damage within melanocytes depends on ITA. Taken together our results may explain the higher risk of lighter skin types developing skin cancers, including melanoma, as well as the development of pigmentary disorders in moderately pigmented skin. They show that skin classification based on ITA is physiologically relevant (as it correlates with constitutive pigmentation) and further support the concept of a more personalized approach to photoprotection that corresponds to a particular skin colour type's sensitivity to solar UVR.What's already known about this topic?• Sun exposure sensitivity is largely dependent on the degree of skin constitutive pigmentation.What does this study add?• The individual typology angle (ITA)-based skin colour classification correlates with constitutive pigmentation and is physiologically relevant in different geographical areas.• It may help identify differential responses to ultraviolet radiation (UVR) exposure that correspond to particular skin colour type's UVR sensitivities.• It supports the concept of personalized photoprotection.Harmful consequences of sun exposure range from sunburn, photoageing and pigmentary disorders to skin cancer. The incidence and extent of these detrimental effects is largely dependent on the degree of constitutive pigmentation of the skin.1-6 Human skin colour is determined by the total quantity of melanin, the proportion between the brown-black eumelanin

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confidence: 99%

“…8 The importance of UVB-induced apoptotic cell death as a protective mechanism becomes evident by the fact that the reduced risk of dark-skinned individuals to develop skin cancer is, to a major part, due to facilitation of UVB-induced epidermal apoptosis by melanin. 9 In addition, the property of several plant polyphenols to prevent UVB-induced skin carcinogenesis is also attributed to their ability to increase apoptosis in epidermal cells. 6 We have previously shown that UVB exposure of keratinocyte (KC) resulted in the activation of the aryl hydrocarbon receptor (AHR), 10 a ligand-activated transcription factor and central regulator of drug metabolism.…”

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confidence: 99%

Evidence for a novel anti-apoptotic pathway in human keratinocytes involving the aryl hydrocarbon receptor, E2F1, and checkpoint kinase 1

et al. 2013

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Exposure of keratinocytes (KC) to ultraviolet (UV) radiation results in the initiation of apoptosis, a protective mechanism that eliminates cells harboring irreparable DNA damage. Hence, a manipulation of UV-induced apoptosis may significantly influence photocarcinogenesis. We have discovered that the aryl hydrocarbon receptor (AHR), a key regulator of drug metabolism and an UVB-sensitive transcription factor, serves an anti-apoptotic function in UVB-irradiated human KC. Chemical and shRNA-mediated inhibition of AHR signaling sensitized KC to UVB-induced apoptosis by decreasing the expression of E2F1 and its target gene checkpoint kinase 1 (CHK1). The decreased expression of these cell-cycle regulators was due to an enhanced expression of p27 KIP1 and an associated decrease in phosphorylation of both cyclin-dependent kinase 2 and its substrate molecule retinoblastoma protein. The subsequent inhibition of E2F1 autoregulation and downstream CHK1 expression resulted in an enhanced susceptibility of damaged cells to undergo apoptosis. Accordingly, ectopic overexpression of either E2F1 or CHK1 in AHR-knockdown KC attenuated the observed sensitization to UVB-induced apoptosis. Using an AHR-knockout SKH-1 hairless mouse model, we next demonstrated the physiological relevance of the anti-apoptotic function of AHR. In contrast to their AHR-proficient littermates, the constitutive expression of E2F1 and CHK1 was significantly reduced in the skin of AHR-knockout mice. Accordingly, a single exposure of the animals to UVB resulted in an enhanced cleavage of caspase-3 in the skin of AHR-knockout mice. These results identify for the first time the AHR-E2F1-CHK1 axis as a novel anti-apoptotic pathway in KC, which may represent a suitable target for chemoprevention of non-melanoma skin cancer. With an annual incidence of two to three million new cases worldwide, non-melanoma skin cancer (NMSC) is one of the most frequent forms of cancer in humans (World Health Organization; http://www.who.int/uv/faq/skincancer/en/index1 .html). Typically, NMSCs, such as basal cell and squamous cell carcinomas, occur on sun-exposed areas of the skin, indicating that solar ultraviolet (UV) radiation, especially its UVB part (290-320 nm), is the most important etiological factor. 1,2 In fact, it is well established that UVB radiation gives rise to skin cancer without additional initiators or promoters and thus is a complete carcinogen. 1 Because of the thinning of the ozone layer, the increase in recreational sunbathing and the enhanced usage of UV tanning beds, the incidence of NMSC is expected to increase in future years, 1,2 underscoring the urgent need for novel preventives against UV-induced skin malignancies.When skin is exposed to solar radiation, high-energy UVB photons penetrate into the epidermis and initiate the so-called UVB response. 3 The main trigger of this stress response is the absorbance of UVB rays by DNA, which leads to the generation of highly mutagenic DNA photoproducts. 3,4 In addition, UVB exposure results in the formation...

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Human skin responses to UV radiation: pigment in the upper epidermis protects against DNA damage in the lower epidermis and facilitates apoptosis

Cited by 180 publications

References 41 publications

Sialylated Core 1 O-Glycans Influence the Sorting of Pmel17/gp100 and Determine Its Capacity to Form Fibrils

Sialylated Core 1 O-Glycans Influence the Sorting of Pmel17/gp100 and Determine Its Capacity to Form Fibrils

Variations in skin colour and the biological consequences of ultraviolet radiation exposure

Evidence for a novel anti-apoptotic pathway in human keratinocytes involving the aryl hydrocarbon receptor, E2F1, and checkpoint kinase 1

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