Deep intronic founder mutations identified in the ERCC4/XPF gene are potential therapeutic targets for a high-frequency form of xeroderma pigmentosum.

Xeroderma pigmentosum (XP) is a genodermatosis defined by cutaneous photosensitivity with an increased risk of skin tumors because of DNA repair deficiency. The worldwide prevalence of XP is ~1 to 4 in million, with higher incidence in some countries and regions including Japan (1 in 22,000) and North Africa due to founder mutations and a high degree of consanguinity. Among XP, the complementation group F (XP-F), is a rare form (1% of worldwide XP); however, this is underdiagnosed, because the ERCC4/XPF gene is essential for fetal development and most of previously reported ERCC4/XPF pathogenic variants are hypomorphs causing relatively mild phenotypes. From the largest Japanese XP cohort study, we report 17 XP-F cases bearing two pathogenic variants, both identified in deep intronic regions of the ERCC4/XPF gene. The first variant, located in intron 1, is a Japanese founder mutation, which additionally accounts for ~10% of the entire Japanese XP cases (MAF = 0.00196), causing an aberrant pre-mRNA splicing due to a miss-binding of U1snRNA. The second mutation located in intron eight induces an alternative polyadenylation. Both mutations cause a reduction of the ERCC4/XPF gene expression, resulting in XP clinical manifestations. Most cases developed early-onset skin cancers, indicating that these variants need critical attention. We further demonstrate that antisense oligonucleotides designed for the mutations can restore the XPF protein expression and DNA repair capacity in the patients' cells. Collectively, these pathogenic variants can be potential therapeutic targets for XP.

Clinical trial on the efficacy and safety of NPC-15 for patients with xeroderma pigmentosum exaggerated sunburn reaction type: XP-1 study protocol for a multicentre, double-blinded, placebo-controlled, two-group crossover study followed by a long-term open study in Japan.

INTRODUCTION: Xeroderma pigmentosum (XP) is a rare intractable disease without a fundamental treatment, presenting with severe photosensitivity, freckle-like pigmented and depigmented maculae and numerous skin cancers before the age of 10 years without strict sun protection. About 70% of the patients exhibit extremely severe sunburn reactions and most of them develop neurological symptoms, including sensorineural hearing impairment and progressive peripheral and central nervous disorders beginning from childhood ages. In the preclinical study, we found that N-acetyl-5-methoxytryptamine was effective in suppressing skin tumour development in addition to improvement of auditory brainstem response in chronically ultraviolet-irradiated XP-A model mice. METHODS AND ANALYSIS: On the bases of the preclinical study, we conduct a clinical trial on the efficacy of NPC-15 for patients with XP with exaggerated sunburn reaction type by a multicentre, double-blinded placebo-controlled, two-group crossover study followed by a 52 weeks open study. ETHICS AND DISSEMINATION: Ethics approval is overseen by the Kobe University Institutional Review Board and Osaka Medical and Pharmaceutical University Institutional Review Board, and the study is conducted in accordance with the approved protocol. All participants will be required to provide written informed consent. Findings will be disseminated through scientific and professional conferences and peer-reviewed journal publications. The data sets generated during the study will be available from the corresponding author on reasonable request. TRIAL REGISTRATION NUMBER: jRCTs051210181.

Replication-related genes are upregulated in XP-A cells after UV-C irradiation.

BACKGROUND: Xeroderma pigmentosum (XP) is hereditary disorder characterized by photosensitivity, predisposition to skin cancers of sun-exposed body sites and progressive neurologic symptoms in some cases. Cells from XP patients show higher sensitivity to ultraviolet radiation (UV) than normal cells. OBJECTIVE: We aimed to ascertain the genes differentially regulated in XP complementation group A (XP-A) cells after UV irradiation. METHODS: XP-A cells were harvested at 4 or 12 h after a single exposure to low-dose UV-C radiation and subjected to transcriptome analysis by microarray. RESULTS: The number of genes with significantly altered expression (≥2-fold difference) at 12 h was markedly higher in XP-A cells than that in normal cells, suggesting that the number of altered genes could be correlated to the amount of DNA damage. CONCLUSION: We recently reported that mitotic genes are induced in normal human fibroblasts after UV-C exposure, and similar results were observed in XP-A cells as normal cells. In addition, a majority of replication-related genes were significantly upregulated in XP-A cells, whereas no such expression pattern was observed in the normal control cells. Collectively, these results indicate that the XPA protein can transcriptionally inhibit the series of replication-related genes, and could possibly regulate replication and/or re-replication after UV irradiation.

Characteristics of Xeroderma Pigmentosum in Japan: Lessons From Two Clinical Surveys and Measures for Patient Care.

Xeroderma pigmentosum (XP) is a rare autosomal recessive hereditary disease caused by deficiency in repair of DNA lesions generated by ultraviolet radiation and other compounds. Patients with XP display pigmentary change and numerous skin cancers in sun-exposed sites, and some patients show exaggerated severe sunburns even upon minimum sun exposure as well as neurological symptoms. We conducted a nationwide survey for XP since 1980. In Japan, the frequency of the XP complementation group A is the highest, followed by the variant type; while in the Western countries, those of groups C or D are the highest. Regarding skin cancers in XP, basal cell carcinoma was the most frequent cancer that afflicted patients with XP, followed by squamous cell carcinoma, and malignant melanoma. The frequency of these skin cancers in patients with XP has decreased in these 20 years, and the age of onset of developing skin cancers is higher than those previously observed, owing to early diagnosis and education to patients and care takers on strict prevention from sunlight for patients with XP. On the other hand, the effective therapy for neurological XP has not been established yet, and this needs to be done urgently.

A case of acute heart failure due to myocardial infiltration of mycosis fungoides.

Mycosis fungoides (MF) has been reported to be the most common cutaneous lymphoma with a good prognosis and myocardial infiltration is clinically rare. We hereby report a case of rapidly progressing acute heart failure due to myocardial infiltration by MF. Perfusion cardiac magnetic resonance imaging (MRI) demonstrated a massive perfusion defect in the left ventricle (LV) where multiple nodular enhancement areas by delayed enhancement MRI could be documented in the postero-lateral wall of the LV, which resulted in a deterioration of the LV function and mitral regurgitation. Autopsy confirmed the myocardial infiltration by the MF, which corresponded with the MRI findings. .

4-(4-Hydroxyphenyl)-2-butanol (rhododendrol)-induced melanocyte cytotoxicity is enhanced by UVB exposure through generation of oxidative stress.

4-(4-Hydroxyphenyl)-2-butanol (rhododendrol, RD), a skin-whitening agent, was reported to cause skin depigmentation in some users, which is attributed to its cytotoxicity to melanocyte. It was reported that cytotoxicity to melanocyte is possibly mediated by oxidative stress in a tyrosinase activity-dependent manner. We examined the effect of UV radiation (UVR) on RD-induced melanocyte cytotoxicity as an additional aggravating factor. UVR enhanced RD-induced cytotoxicity in normal human epidermal melanocytes (NHEMs) via the induction of endoplasmic reticulum (ER) stress. Increased generation of intracellular reactive oxygen species (ROS) was detected. Pretreatment with N-acetyl cysteine (NAC), antioxidant and precursor of glutathione significantly attenuated ER stress-induced cytotoxicity in NHEMs treated with RD and UVR. Increase in cysteinyl-RD-catechol and RD-pheomelanin in NHEMs treated with RD and UVR suggested that, after UVR excitation, RD or RD metabolites are potent ROS-generating substances and that the tendency to produce RD-pheomelanin during melanogenesis amplifies ROS generation in melanocytes. Our results help to elucidate the development mechanisms of RD-induced leukoderma and provide information for innovation of safe skin-whitening compounds.

NF-E2 p45 is important for establishing normal function of platelets.

NF-E2 is a heterodimeric transcription factor consisting of p45 and small Maf subunits. Since p45(-/-) mice display severe thrombocytopenia, p45 is recognized as a critical regulator of platelet production from megakaryocytes. To identify direct p45 target genes in megakaryocytes, we used chromatin immunoprecipitation (ChIP) sequencing to analyze the genome-wide chromatin occupancy of p45 in primary megakaryocytes. p45 target gene candidates obtained from the analysis are implicated in the production and function of platelets. Two of these genes, Selp and Myl9, were verified as direct p45 targets through multiple approaches. Since P-selectin, encoded by Selp, plays a critical role in platelet function during thrombogenesis, we tested whether p45 determines the intrinsic reactivity and potency of platelets generated from megakaryocytes. Mice expressing a hypomorphic p45 mutant instead of wild-type p45 in megakaryocytes (p45(-/-):ΔNTD-Tg mice) displayed platelet hypofunction accompanied by mild thrombocytopenia. Furthermore, lung metastasis of melanoma cells, which requires platelet activation, was repressed in p45(-/-):ΔNTD-Tg mice compared to control mice, validating the impaired function of platelets produced from p45(-/-):ΔNTD-Tg megakaryocytes. By activating genes in megakaryocytes that mediate platelet production and function, p45 determines the quantity and quality of platelets.