- Email: [email protected]
Possible role of infrared or heat in sun-induced changes of dermis of human skin in vivo
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Letters to the Editor / Journal of Dermatological Science 66 (2012) 71–84
Taken together, our results show that engagement of surface SIRP-a and the lack of its cytoplasmic region in DCs inhibit the chemotaxis of DCs via the suppression of Rho/Rho kinase activation. Our study indicates that the migration of DCs is regulated by the Rho/Rho kinase pathway as a downstream signaling of SIRP-a. It also suggests that the Rho/Rho kinase pathway may be involved in other skin inflammatory diseases such as atopic dermatitis and/or psoriasis vulgaris
[8] Rikitake Y, Kim HH, Huang Z, Seto M, Yano K, Asano T, et al. Inhibition of Rho kinase (ROCK) leads to increased cerebral blood flow and stroke protection. Stroke 2005;36:2251–7. [9] Lutz MB, Kukutsch N, Ogilvie AL, Ro¨bner S, Koch F, Romani N, et al. An advanced culture method for generating large quantities of highly pure dendritic cells from mouse bone marrow. J Immunol Methods 1999;223: 77–92. [10] Tanizaki H, Egawa G, Inaba K, Honda T, Nakajima S, Moniaga CS, et al. RhomDia1 pathway is required for adhesion, migration, and T-cell stimulation in dendritic cells. Blood 2010;116(26):5875–84.
References [1] Fukunaga A, Nagai H, Noguchi T, Okazawa H, Matozaki T, Yu X, et al. Src homology 2 domain-containing protein tyrosine phosphatase substrate 1 regulates the migration of Langerhans cells from the epidermis to draining lymph nodes. J Immunol 2004;172:4091–9. [2] Takaishi K, Kikuchi A, Kuroda S, Kotani K, Sasaki T, Takai Y. Involvement of rho p21 and its inhibitory GDP/GTP exchange protein (rho GDI) in cell motility. Mol Cell Biol 1993;13:72–9. [3] Kawano Y, Fukata Y, Oshiro N, Amano M, Nakamura T, Ito M, et al. Phosphorylation of myosin-binding subunit (MBS) of myosin phosphatase by Rhokinase in vivo. J Cell Biol 1999;147:1023–38. [4] Kobayashi M, Azuma E, Ido M, Hirayama M, Jiang Q, Iwamoto S, et al. A pivotal role of Rho GTPase in the regulation of morphology and function of dendritic cells. J Immunol 2001;167:3585–91. [5] Inagaki K, Yamao T, Noguchi T, Matozaki T, Fukunaga K, Takada T, et al. SHPS-1 regulates integrin-mediated cytoskeletal reorganization and cell motility. EMBO J 2000;19:6721–31. [6] Kodama A, Matozaki T, Fukuhara A, Kikyo M, Ichihashi M, Takai Y. Involvement of an SHP-2-Rho small G protein pathway in hepatocyte growth factor/scatter factor-induced cell scattering. Mol Biol Cell 2000;11:2565–75. [7] Motegi S, Okazawa H, Ohnishi H, Sato R, Kaneko Y, Kobayashi H, et al. Role of the CD47-SHPS-1 system in regulation of cell migration. EMBO J 2003;22:2634–44.
Kanako Oguraa, Atsushi Fukunagaa,*, Kumiko Taguchia, Hiroshi Nagaia, Xijun Yua, Shuntaro Onikia, Hideki Okazawab, Takashi Matozakib, Tatsuya Horikawaa, Chikako Nishigoria a Division of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Japan b Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan *Corresponding author. Tel.: +81 78 382 6134; fax: +81 78 382 6149 E-mail address: [email protected] (A. Fukunaga) 2 September 2011 doi:10.1016/j.jdermsci.2012.02.003
Letter to the Editor Possible role of infrared or heat in sun-induced changes of dermis of human skin in vivo The signs of photoaging in human skin have been attributed almost exclusively to the ultraviolet radiation (UVR) which represents just 6.8% of solar radiation, compared to the infrared and visible radiation which account for 54.3% and 38.9%, respectively, of the incident solar energy [1]. Little is known about the biologic effects of non-UVR components of solar radiation on human skin. Recent studies suggest that infrared radiation induces extracellular matrix (ECM) changes including increased matrix metalloproteinases and decreased procollagen expression [2,3], which manifest over time as wrinkles [4]. Additionally, increased skin temperature by infrared radiation [5] as well as heat alone [2,6,7] can cause ECM changes similar to UVR. Even though infrared or heat may contribute to changes in human skin, it is difficult to distinguish between the changes in the superficial dermis induced by UVR and other components due to the overwhelming effect of UVR. UVR penetrates into superficial dermis, whereas other electromagnetic radiations with longer wavelengths, such as infrared or visible light, can penetrate deep into dermis or subcutis [1,8]. Thus if any sun-induced changes are detected in the deep dermis of sun-exposed human skin compared to non-exposed skin of the same individual, other factors except UVR such as infrared or heat may contribute these changes. However, UVR-induced inflammation in the superficial dermis may result in the biologic effects in the deep dermis. Thus we decided to investigate sun-induced changes both in lightly and darkly pigmented skin. If UVR exclusively contributes to the suninduced changes in the deep dermis as in the superficial dermis, aged Caucasians will show significant changes in the deep dermis,
but aged African-Americans will show less significant sun-induced changes in the deep dermis due to UV protection effect of melanin. Since solar elastosis is the histological hallmark of photoaging [9], we performed immunohistochemical analysis for tropoelastin to quantify the elastic material of solar elastosis from young and aged Caucasian (skin phototype II or III) and African-American (skin phototype V or VI) subjects. The conduct of this study fell under the guidelines of both the Declaration of Helsinki and the Good Clinical Practice regulations. All subjects were required to give written informed consent prior to the initiation of study. This study protocol was approved by the Greater Delaware Valley Institutional Review Board. Twenty-one female volunteers were enrolled in this study: 5 young Caucasians (mean age, 23.2 2.7 year), 5 aged Caucasians (mean age, 62.8 7.7 year), 6 young African-Americans (mean age, 24.0 0.6 years), and 5 aged African-Americans (mean age, 59.8 3.6 year). We examined paraffin-embedded skin samples from two anatomical sites: sun-exposed outer lower arms and relatively non-exposed upper inner arm. Immunohistochemical analysis using polyclonal anti-human tropoelastin antibody (Elastin Products Company, Owensville, MO) was performed to detect elastic material. We measured the amount of tropoelastin-immunoreactive materials within each 80 mm interval from dermo-epidermal junction to 800 mm deep into the dermis (a total of 10 intervals). Interestingly, the distribution of elastin-immunoreactive material was completely different between young Caucasians (Fig. 1A) and African-Americans (Fig. 1C). There was no difference in the amount of elastin-immunoreactive material between non-exposed and exposed skin in young Caucasians (Fig. 1A). However, almost all skin layers of the exposed skin of every young AfricanAmericans showed significantly less elastin-immunoreactive material compared to non-exposed skin of the same individuals
Letters to the Editor / Journal of Dermatological Science 66 (2012) 71–84
77
Fig. 1. Comparison of tropoelastin-immunoreactive material in sun-exposed and sun-protected skin. Total area (percentage) occupied by tropoelastin-immunoreactive material within each region was, respectively, calculated in (A) young Caucasians (n = 5), (B) aged Caucasians (n = 5), (C) young African-Americans (n = 6), and (D) old AfricanAmericans (n = 5). Data represent mean SEM. *P values < 0.05 vs. non-exposed skin from same individuals; yP values >0.05 and <0.1 vs. non-exposed skin from same individuals; Wilcoxon’s signed rank test.
(Fig. 1C). To our knowledge, this is the first report of this phenomenon. Even though we cannot explain the mechanism of different distribution of elastin-positive material among phototypes, further investigation is needed to understand this difference. Considering the difference in tropoelastin distribution of young subjects among the phototypes, we could postulate and compare the relative change of elastin distribution of aged Caucasians and African-Americans in the exposed skin. Intrinsic aging seemed to be associated with decreased elastin because there was a tendency toward reduced elastin in the non-exposed skin both in aged Caucasians and African-Americans compared to their counterpart young subjects. Aged Caucasians showed significantly increased elastin (‘solar elastosis’) in the exposed skin compared to the non-exposed skin. By 400 mm deep, elastin increased by about 88.5% in exposed skin compared to non-exposed skin. The differences between exposed and non-exposed skin decreased at 400–640 mm deep (38.2%) and no significant difference was observed at 640–800 mm. We can conclude that solar elastosis of aged Caucasian skin was concentrated within 400 mm deep in dermis (Fig. 1B). While young African-Americans showed significantly reduced elastinpositive material in the exposed skin compared to the non-exposed skin (Fig. 1C), the exposed site of aged African-Americans had a similar or increased elastin compared to non-exposed skin throughout all skin layers (Fig. 1D). Overall, our results demonstrate that aged Caucasians showed greater solar elastosis in the superficial dermis, and aged African-Americans had increased elastin until 800 mm deep of exposed skin compared to nonexposed skin. The distribution of the elastic material of solar elastosis in deep dermis of aged subjects seems to be explained as follows: first, UV may penetrate deeper than previous postulation. Second, any paracrine effect of soluble factors originated from epidermis or
superficial dermis in the exposed skin may cause biologic effects contributing to remote sun-induced changes. Third, electromagnetic radiation with longer wavelengths may contribute to solarinduced changes in deep dermis, particularly the infrared radiation that represents half of solar energy and has wavelengths long enough to penetrate to deep dermis. In addition, infrared radiation can be absorbed by the skin and converted into heat which increases the skin temperature [5] and induces sun-induced damages [6,7]. Since we also observed sun-induced changes in the deep dermis of African-Americans in spite of UVR protection effect of melanin, our results suggest that electromagnetic radiation except UVR or heat might explain solar-induced changes in the deep dermis. Future studies are needed to investigate the underlying molecular mechanisms of electromagnetic radiation other than UVR. Acknowledgements This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2010-0028725) and by a research agreement with the Estee Lauder Inc. References [1] Kochevar IE, Taylor CR, Krutmann J. Fundamentals of cutaneous photobiology and photoimmunology. In: Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, editors. Fitzpatrick’s dermatology in general medicine. New York: McGraw-Hill; 2008. p. 797–809. [2] Cho S, Lee MJ, Kim MS, Lee S, Kim YK, Lee DH, et al. Infrared plus visible light and heat from natural sunlight participate in the expression of MMPs and type I procollagen as well as infiltration of inflammatory cell in human skin in vivo. J Dermatol Sci 2008;50:123–33. [3] Kligman LH. Intensification of ultraviolet-induced dermal damage by infrared radiation. Arch Dermatol Res 1982;272:229–38.
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Letters to the Editor / Journal of Dermatological Science 66 (2012) 71–84
[4] Kim HH, Lee MJ, Lee SR, Kim KH, Cho KH, Eun HC, et al. Augmentation of UVinduced skin wrinkling by infrared irradiation in hairless mice. Mech Ageing Dev 2005;126:1170–7. [5] Darvin ME, Haag SF, Lademann J, Zastrow L, Sterry W, Meinke MC. Formation of free radicals in human skin during irradiation with infrared light. J Invest Dermatol 2009;130:629–31. [6] Park CH, Lee MJ, Ahn J, Kim S, Kim HH, Kim KH, et al. Heat shock-induced matrix metalloproteinase (MMP)-1 and MMP-3 are mediated through ERK and JNK activation and via an autocrine interleukin-6 loop. J Invest Dermatol 2004;123:1012–9. [7] Shin MH, Moon YJ, Seo JE, Lee Y, Kim KH, Chung JH. Reactive oxygen species produced by NADPH oxidase, xanthine oxidase, and mitochondrial electron transport system mediate heat shock-induced MMP-1 and MMP-9 expression. Free Radic Biol Med 2008;44:635–45. [8] Meinhardt M, Krebs R, Anders A, Heinrich U, Tronnier H. Wavelength-dependent penetration depths of ultraviolet radiation in human skin. J Biomed Opt 2008;13:044030–035. [9] Sellheyer K. Pathogenesis of solar elastosis: synthesis or degradation? J Cutan Pathol 2003;30:123–7.
Hyun-Sun Yoona,b,c, Yeon Kyung Kima,b,c, Mary Matsuid,**, Jin Ho Chunga,b,c,* a Department of Dermatology, Seoul National University College of Medicine, Seoul, Republic of Korea
b
Laboratory of Cutaneous Aging Research, Clinical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea c Institute of Dermatological Science, Seoul National University, Seoul, Republic of Korea d Estee Lauder Companies Research and Development Basic Science Research, Melville, NY, USA *Corresponding author at: Department of Dermatology, Seoul National University College of Medicine, 28-Yeongeon-dong, Jongno-gu, Seoul 110-744, Korea. Tel.: +82 2 2072 2414; fax: +82 2 742 7344 E-mail address: [email protected] (J. H. Chung) **Corresponding author. Tel.: +1 631 531 1665; fax: +1 631 531 1737 E-mail address: [email protected] (M. Matsui) 14 February 2011 doi:10.1016/j.jdermsci.2011.12.003
Letters to the Editor Molecular characterization of two novel KIT mutations in patients with piebaldism
Keywords: Piebaldism; KIT gene; Mutation
Piebaldism (OMIM 172800) is a rare autosomal dominant disorder characterized by congenital depigmented patches of the mid-forehead, chest, abdomen and extremities [1]. The disorder is caused by inactivating mutations or deletions of the KIT gene on chromosome 4q12 or the SLUG gene on chromosome 8q11. Here we report two new KIT mutations, a missense mutation p.T619A and an in frame p.T437dup duplication, associated with piebaldism and we show that both non-protein truncating mutations have an inactivating effect on the KIT protein and are pathogenic. Patient 1. A 14 year old female presented with large depigmented skin spots on the arms, legs and the abdomen. The depigmented areas were noticed at the age of 1 year and were very sensitive to sunburn. In addition, a few hyperpigmented spots on the thorax were observed. The patient had a normal intellectual development, hearing and vision, blond hairs, blue eyes and freckles on her face. She is the second child in a family with three children. Brothers and parents did not present any signs of piebald trait. Patient 2. This male patient was referred at the age of 40 years. He had a white forelock and depigmented skin spots on the thorax, abdomen, arms and legs. He had two similarly affected children, a girl and boy who were examined at the age of 11 and 12 years, respectively. The patient and both of his children had normal hearing, vision and normal intellectual development. The parents of the proband were not affected. Genomic DNA was extracted from peripheral blood samples collected after obtaining informed consent. All exons and intronic boundaries of KIT were amplified and the PCR products were
sequenced. In addition, molecular analysis of KIT was performed in both children of Patient 2. The study was approved by the local ethical committee of the University Hospital. In Patient 1, a c.1855 A>G (p.T619A) missense mutation was detected in the cytoplasmic tyrosine kinase domain encoded by exon 12. Direct sequencing of PCR products of KIT in Patient 2 revealed the presence of a mutation at codon 437 (c.14061408dupACA) in exon 8. A p.T437dup has also been detected in both affected children of the proband suggesting a pathogenic role for this alteration. In the same patient 2, we also detected the c.67+4G>A substitution. This alteration has been previously described as a potential pathogenic germline variant in piebaldism [2]. Romagnoli et al. reported c.67+4G>A in two patients with gastrointestinal stromal tumors (GISTs) without the piebald trait. In addition, they found the same substitution in three out of 100 healthy individuals, thus confirming c.67+4G>A as a polymorphism [3]. Our results are in line with this finding. In contrast to p.T437dup, the c.67+4G>A substitution has not been detected in the affected children of patient 2. Therefore, we can confirm that the c.67+4G>A alteration is a polymorphic variant not associated with piebaldism. For mutation p.T619A it is assumed that this single amino acid substitution can affect the highly conserved cytoplasmic tyrosine kinase domain. KIT mutations in the vicinity of codon 620 were previously described in piebald patients [2,4,5]. Almost all known mutations in this region result in a severe phenotype of piebaldism. Both p.T437dup and p.T619A were not found in a group of 50 healthy individuals tested by direct sequencing. This indicates that these mutations are not polymorphisms. To date, mutations in exon 8 such as p.T437dup detected in patient 2 have been reported only in a group of patients with acute myeloid leukemia (AML), and in one kindred with both GIST and mastocytosis [6,7]. All previously reported genetic variants constitutively activated the KIT receptor. To investigate the pathogenicity of the detected mutations, wild-type and mutant KIT cDNA was cloned into a pcDNA3.1 (Invitrogen) construct. KIT mutants KIT-T619A, KIT-T437dup and a known activating mutant, KIT-N822I were generated by PCRdirected mutagenesis. All constructs were encoding the GNNK-
Letters to the Editor / Journal of Dermatological Science 66 (2012) 71–84
Taken together, our results show that engagement of surface SIRP-a and the lack of its cytoplasmic region in DCs inhibit the chemotaxis of DCs via the suppression of Rho/Rho kinase activation. Our study indicates that the migration of DCs is regulated by the Rho/Rho kinase pathway as a downstream signaling of SIRP-a. It also suggests that the Rho/Rho kinase pathway may be involved in other skin inflammatory diseases such as atopic dermatitis and/or psoriasis vulgaris
[8] Rikitake Y, Kim HH, Huang Z, Seto M, Yano K, Asano T, et al. Inhibition of Rho kinase (ROCK) leads to increased cerebral blood flow and stroke protection. Stroke 2005;36:2251–7. [9] Lutz MB, Kukutsch N, Ogilvie AL, Ro¨bner S, Koch F, Romani N, et al. An advanced culture method for generating large quantities of highly pure dendritic cells from mouse bone marrow. J Immunol Methods 1999;223: 77–92. [10] Tanizaki H, Egawa G, Inaba K, Honda T, Nakajima S, Moniaga CS, et al. RhomDia1 pathway is required for adhesion, migration, and T-cell stimulation in dendritic cells. Blood 2010;116(26):5875–84.
References [1] Fukunaga A, Nagai H, Noguchi T, Okazawa H, Matozaki T, Yu X, et al. Src homology 2 domain-containing protein tyrosine phosphatase substrate 1 regulates the migration of Langerhans cells from the epidermis to draining lymph nodes. J Immunol 2004;172:4091–9. [2] Takaishi K, Kikuchi A, Kuroda S, Kotani K, Sasaki T, Takai Y. Involvement of rho p21 and its inhibitory GDP/GTP exchange protein (rho GDI) in cell motility. Mol Cell Biol 1993;13:72–9. [3] Kawano Y, Fukata Y, Oshiro N, Amano M, Nakamura T, Ito M, et al. Phosphorylation of myosin-binding subunit (MBS) of myosin phosphatase by Rhokinase in vivo. J Cell Biol 1999;147:1023–38. [4] Kobayashi M, Azuma E, Ido M, Hirayama M, Jiang Q, Iwamoto S, et al. A pivotal role of Rho GTPase in the regulation of morphology and function of dendritic cells. J Immunol 2001;167:3585–91. [5] Inagaki K, Yamao T, Noguchi T, Matozaki T, Fukunaga K, Takada T, et al. SHPS-1 regulates integrin-mediated cytoskeletal reorganization and cell motility. EMBO J 2000;19:6721–31. [6] Kodama A, Matozaki T, Fukuhara A, Kikyo M, Ichihashi M, Takai Y. Involvement of an SHP-2-Rho small G protein pathway in hepatocyte growth factor/scatter factor-induced cell scattering. Mol Biol Cell 2000;11:2565–75. [7] Motegi S, Okazawa H, Ohnishi H, Sato R, Kaneko Y, Kobayashi H, et al. Role of the CD47-SHPS-1 system in regulation of cell migration. EMBO J 2003;22:2634–44.
Kanako Oguraa, Atsushi Fukunagaa,*, Kumiko Taguchia, Hiroshi Nagaia, Xijun Yua, Shuntaro Onikia, Hideki Okazawab, Takashi Matozakib, Tatsuya Horikawaa, Chikako Nishigoria a Division of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Japan b Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan *Corresponding author. Tel.: +81 78 382 6134; fax: +81 78 382 6149 E-mail address: [email protected] (A. Fukunaga) 2 September 2011 doi:10.1016/j.jdermsci.2012.02.003
Letter to the Editor Possible role of infrared or heat in sun-induced changes of dermis of human skin in vivo The signs of photoaging in human skin have been attributed almost exclusively to the ultraviolet radiation (UVR) which represents just 6.8% of solar radiation, compared to the infrared and visible radiation which account for 54.3% and 38.9%, respectively, of the incident solar energy [1]. Little is known about the biologic effects of non-UVR components of solar radiation on human skin. Recent studies suggest that infrared radiation induces extracellular matrix (ECM) changes including increased matrix metalloproteinases and decreased procollagen expression [2,3], which manifest over time as wrinkles [4]. Additionally, increased skin temperature by infrared radiation [5] as well as heat alone [2,6,7] can cause ECM changes similar to UVR. Even though infrared or heat may contribute to changes in human skin, it is difficult to distinguish between the changes in the superficial dermis induced by UVR and other components due to the overwhelming effect of UVR. UVR penetrates into superficial dermis, whereas other electromagnetic radiations with longer wavelengths, such as infrared or visible light, can penetrate deep into dermis or subcutis [1,8]. Thus if any sun-induced changes are detected in the deep dermis of sun-exposed human skin compared to non-exposed skin of the same individual, other factors except UVR such as infrared or heat may contribute these changes. However, UVR-induced inflammation in the superficial dermis may result in the biologic effects in the deep dermis. Thus we decided to investigate sun-induced changes both in lightly and darkly pigmented skin. If UVR exclusively contributes to the suninduced changes in the deep dermis as in the superficial dermis, aged Caucasians will show significant changes in the deep dermis,
but aged African-Americans will show less significant sun-induced changes in the deep dermis due to UV protection effect of melanin. Since solar elastosis is the histological hallmark of photoaging [9], we performed immunohistochemical analysis for tropoelastin to quantify the elastic material of solar elastosis from young and aged Caucasian (skin phototype II or III) and African-American (skin phototype V or VI) subjects. The conduct of this study fell under the guidelines of both the Declaration of Helsinki and the Good Clinical Practice regulations. All subjects were required to give written informed consent prior to the initiation of study. This study protocol was approved by the Greater Delaware Valley Institutional Review Board. Twenty-one female volunteers were enrolled in this study: 5 young Caucasians (mean age, 23.2 2.7 year), 5 aged Caucasians (mean age, 62.8 7.7 year), 6 young African-Americans (mean age, 24.0 0.6 years), and 5 aged African-Americans (mean age, 59.8 3.6 year). We examined paraffin-embedded skin samples from two anatomical sites: sun-exposed outer lower arms and relatively non-exposed upper inner arm. Immunohistochemical analysis using polyclonal anti-human tropoelastin antibody (Elastin Products Company, Owensville, MO) was performed to detect elastic material. We measured the amount of tropoelastin-immunoreactive materials within each 80 mm interval from dermo-epidermal junction to 800 mm deep into the dermis (a total of 10 intervals). Interestingly, the distribution of elastin-immunoreactive material was completely different between young Caucasians (Fig. 1A) and African-Americans (Fig. 1C). There was no difference in the amount of elastin-immunoreactive material between non-exposed and exposed skin in young Caucasians (Fig. 1A). However, almost all skin layers of the exposed skin of every young AfricanAmericans showed significantly less elastin-immunoreactive material compared to non-exposed skin of the same individuals
Letters to the Editor / Journal of Dermatological Science 66 (2012) 71–84
77
Fig. 1. Comparison of tropoelastin-immunoreactive material in sun-exposed and sun-protected skin. Total area (percentage) occupied by tropoelastin-immunoreactive material within each region was, respectively, calculated in (A) young Caucasians (n = 5), (B) aged Caucasians (n = 5), (C) young African-Americans (n = 6), and (D) old AfricanAmericans (n = 5). Data represent mean SEM. *P values < 0.05 vs. non-exposed skin from same individuals; yP values >0.05 and <0.1 vs. non-exposed skin from same individuals; Wilcoxon’s signed rank test.
(Fig. 1C). To our knowledge, this is the first report of this phenomenon. Even though we cannot explain the mechanism of different distribution of elastin-positive material among phototypes, further investigation is needed to understand this difference. Considering the difference in tropoelastin distribution of young subjects among the phototypes, we could postulate and compare the relative change of elastin distribution of aged Caucasians and African-Americans in the exposed skin. Intrinsic aging seemed to be associated with decreased elastin because there was a tendency toward reduced elastin in the non-exposed skin both in aged Caucasians and African-Americans compared to their counterpart young subjects. Aged Caucasians showed significantly increased elastin (‘solar elastosis’) in the exposed skin compared to the non-exposed skin. By 400 mm deep, elastin increased by about 88.5% in exposed skin compared to non-exposed skin. The differences between exposed and non-exposed skin decreased at 400–640 mm deep (38.2%) and no significant difference was observed at 640–800 mm. We can conclude that solar elastosis of aged Caucasian skin was concentrated within 400 mm deep in dermis (Fig. 1B). While young African-Americans showed significantly reduced elastinpositive material in the exposed skin compared to the non-exposed skin (Fig. 1C), the exposed site of aged African-Americans had a similar or increased elastin compared to non-exposed skin throughout all skin layers (Fig. 1D). Overall, our results demonstrate that aged Caucasians showed greater solar elastosis in the superficial dermis, and aged African-Americans had increased elastin until 800 mm deep of exposed skin compared to nonexposed skin. The distribution of the elastic material of solar elastosis in deep dermis of aged subjects seems to be explained as follows: first, UV may penetrate deeper than previous postulation. Second, any paracrine effect of soluble factors originated from epidermis or
superficial dermis in the exposed skin may cause biologic effects contributing to remote sun-induced changes. Third, electromagnetic radiation with longer wavelengths may contribute to solarinduced changes in deep dermis, particularly the infrared radiation that represents half of solar energy and has wavelengths long enough to penetrate to deep dermis. In addition, infrared radiation can be absorbed by the skin and converted into heat which increases the skin temperature [5] and induces sun-induced damages [6,7]. Since we also observed sun-induced changes in the deep dermis of African-Americans in spite of UVR protection effect of melanin, our results suggest that electromagnetic radiation except UVR or heat might explain solar-induced changes in the deep dermis. Future studies are needed to investigate the underlying molecular mechanisms of electromagnetic radiation other than UVR. Acknowledgements This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2010-0028725) and by a research agreement with the Estee Lauder Inc. References [1] Kochevar IE, Taylor CR, Krutmann J. Fundamentals of cutaneous photobiology and photoimmunology. In: Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, editors. Fitzpatrick’s dermatology in general medicine. New York: McGraw-Hill; 2008. p. 797–809. [2] Cho S, Lee MJ, Kim MS, Lee S, Kim YK, Lee DH, et al. Infrared plus visible light and heat from natural sunlight participate in the expression of MMPs and type I procollagen as well as infiltration of inflammatory cell in human skin in vivo. J Dermatol Sci 2008;50:123–33. [3] Kligman LH. Intensification of ultraviolet-induced dermal damage by infrared radiation. Arch Dermatol Res 1982;272:229–38.
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[4] Kim HH, Lee MJ, Lee SR, Kim KH, Cho KH, Eun HC, et al. Augmentation of UVinduced skin wrinkling by infrared irradiation in hairless mice. Mech Ageing Dev 2005;126:1170–7. [5] Darvin ME, Haag SF, Lademann J, Zastrow L, Sterry W, Meinke MC. Formation of free radicals in human skin during irradiation with infrared light. J Invest Dermatol 2009;130:629–31. [6] Park CH, Lee MJ, Ahn J, Kim S, Kim HH, Kim KH, et al. Heat shock-induced matrix metalloproteinase (MMP)-1 and MMP-3 are mediated through ERK and JNK activation and via an autocrine interleukin-6 loop. J Invest Dermatol 2004;123:1012–9. [7] Shin MH, Moon YJ, Seo JE, Lee Y, Kim KH, Chung JH. Reactive oxygen species produced by NADPH oxidase, xanthine oxidase, and mitochondrial electron transport system mediate heat shock-induced MMP-1 and MMP-9 expression. Free Radic Biol Med 2008;44:635–45. [8] Meinhardt M, Krebs R, Anders A, Heinrich U, Tronnier H. Wavelength-dependent penetration depths of ultraviolet radiation in human skin. J Biomed Opt 2008;13:044030–035. [9] Sellheyer K. Pathogenesis of solar elastosis: synthesis or degradation? J Cutan Pathol 2003;30:123–7.
Hyun-Sun Yoona,b,c, Yeon Kyung Kima,b,c, Mary Matsuid,**, Jin Ho Chunga,b,c,* a Department of Dermatology, Seoul National University College of Medicine, Seoul, Republic of Korea
b
Laboratory of Cutaneous Aging Research, Clinical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea c Institute of Dermatological Science, Seoul National University, Seoul, Republic of Korea d Estee Lauder Companies Research and Development Basic Science Research, Melville, NY, USA *Corresponding author at: Department of Dermatology, Seoul National University College of Medicine, 28-Yeongeon-dong, Jongno-gu, Seoul 110-744, Korea. Tel.: +82 2 2072 2414; fax: +82 2 742 7344 E-mail address: [email protected] (J. H. Chung) **Corresponding author. Tel.: +1 631 531 1665; fax: +1 631 531 1737 E-mail address: [email protected] (M. Matsui) 14 February 2011 doi:10.1016/j.jdermsci.2011.12.003
Letters to the Editor Molecular characterization of two novel KIT mutations in patients with piebaldism
Keywords: Piebaldism; KIT gene; Mutation
Piebaldism (OMIM 172800) is a rare autosomal dominant disorder characterized by congenital depigmented patches of the mid-forehead, chest, abdomen and extremities [1]. The disorder is caused by inactivating mutations or deletions of the KIT gene on chromosome 4q12 or the SLUG gene on chromosome 8q11. Here we report two new KIT mutations, a missense mutation p.T619A and an in frame p.T437dup duplication, associated with piebaldism and we show that both non-protein truncating mutations have an inactivating effect on the KIT protein and are pathogenic. Patient 1. A 14 year old female presented with large depigmented skin spots on the arms, legs and the abdomen. The depigmented areas were noticed at the age of 1 year and were very sensitive to sunburn. In addition, a few hyperpigmented spots on the thorax were observed. The patient had a normal intellectual development, hearing and vision, blond hairs, blue eyes and freckles on her face. She is the second child in a family with three children. Brothers and parents did not present any signs of piebald trait. Patient 2. This male patient was referred at the age of 40 years. He had a white forelock and depigmented skin spots on the thorax, abdomen, arms and legs. He had two similarly affected children, a girl and boy who were examined at the age of 11 and 12 years, respectively. The patient and both of his children had normal hearing, vision and normal intellectual development. The parents of the proband were not affected. Genomic DNA was extracted from peripheral blood samples collected after obtaining informed consent. All exons and intronic boundaries of KIT were amplified and the PCR products were
sequenced. In addition, molecular analysis of KIT was performed in both children of Patient 2. The study was approved by the local ethical committee of the University Hospital. In Patient 1, a c.1855 A>G (p.T619A) missense mutation was detected in the cytoplasmic tyrosine kinase domain encoded by exon 12. Direct sequencing of PCR products of KIT in Patient 2 revealed the presence of a mutation at codon 437 (c.14061408dupACA) in exon 8. A p.T437dup has also been detected in both affected children of the proband suggesting a pathogenic role for this alteration. In the same patient 2, we also detected the c.67+4G>A substitution. This alteration has been previously described as a potential pathogenic germline variant in piebaldism [2]. Romagnoli et al. reported c.67+4G>A in two patients with gastrointestinal stromal tumors (GISTs) without the piebald trait. In addition, they found the same substitution in three out of 100 healthy individuals, thus confirming c.67+4G>A as a polymorphism [3]. Our results are in line with this finding. In contrast to p.T437dup, the c.67+4G>A substitution has not been detected in the affected children of patient 2. Therefore, we can confirm that the c.67+4G>A alteration is a polymorphic variant not associated with piebaldism. For mutation p.T619A it is assumed that this single amino acid substitution can affect the highly conserved cytoplasmic tyrosine kinase domain. KIT mutations in the vicinity of codon 620 were previously described in piebald patients [2,4,5]. Almost all known mutations in this region result in a severe phenotype of piebaldism. Both p.T437dup and p.T619A were not found in a group of 50 healthy individuals tested by direct sequencing. This indicates that these mutations are not polymorphisms. To date, mutations in exon 8 such as p.T437dup detected in patient 2 have been reported only in a group of patients with acute myeloid leukemia (AML), and in one kindred with both GIST and mastocytosis [6,7]. All previously reported genetic variants constitutively activated the KIT receptor. To investigate the pathogenicity of the detected mutations, wild-type and mutant KIT cDNA was cloned into a pcDNA3.1 (Invitrogen) construct. KIT mutants KIT-T619A, KIT-T437dup and a known activating mutant, KIT-N822I were generated by PCRdirected mutagenesis. All constructs were encoding the GNNK-