Disorder of the mevalonate pathway inhibits calcium-induced differentiation of keratinocytes.

Mutation of genes encoding the enzymes of the mevalonate pathway cause a variety of diseases, including skin disorders. Mutation of four genes in this pathway, including mevalonate kinase, phosphomevalonate kinase, mevalonate diphosphate decarboxylase and farnesyl diphosphate synthase, have demonstrated to be responsible for porokeratosis (PK). However, the pathogenesis of PK remains unclear. In the present study, specific enzyme inhibitors of the mevalonate pathway, including pravastatin (PRA), alendronate (ALD), farnesyl transferase inhibitor (FTI­277) and geranylgeranyl transferase inhibitor (GGTI­298), were used to investigate the effect on differentiation of keratinocytes (KCs). Western blotting demonstrated that PRA, ALD, FTI­277 or GGTI­298 alone, or in combination, inhibited the expression level of calcium­induced differentiation maker involucrin (INV) in KCs. ALD and PRA induced greater inhibition of INV compared with FTI­277 and GGTI­298 treatment. These inhibitors additionally influenced the expression levels of keratin1. Mechanistic studies revealed that treatment of cells with inhibitors decreased the expression levels of p53 and Notch1, and regulated activation of the mitogen activated protein kinase and phosphoinositide­3­kinase/protein kinase B signaling pathways. The results of the present study suggested that regulation of the mevalonate pathway may be necessary for differentiation of KCs, and the pathogenesis of disseminated superficial actinic PK.

Interleukin-15 inhibits the expression of differentiation markers induced by Ca(2+) in keratinocytes.

Interleukin (IL)-15 is an important proinflammatory cytokine that can protect epidermal keratinocytes (KCs) from ultraviolet-induced apoptosis and plays a role in the pathogenesis of psoriasis. However, the impact of IL-15 on KC differentiation remains unknown. In this study, isolated human primary epidermal KCs were treated with various concentrations of IL-15 for different times, and the expression of differentiation markers (keratin 1, involucrin and loricrin) and p53 as well as the activation of ERK, AKT and Notch induced by IL-15 in the absence or presence of Ca(2+) was detected by real-time PCR and Western blot. The results showed that stimulation with Ca(2+) alone increased the expression of KC differentiation markers and p53 and promoted the activation of Notch1. Pretreatment with IL-15 resulted in a decrease in the Ca(2+) -induced expression of KC differentiation markers and p53. Additionally, Ca(2+) continually inhibited the phosphorylation of ERK1/2 and activated AKT, and IL-15 reduced the effect of Ca(2+) on ERK1/2 and AKT. FR180204, a specific inhibitor of ERK1/2 phosphorylation, slightly attenuated the effect of Ca(2+) on the expression of differentiation markers and p53 and the activation of Notch1. In contrast, MK-2206, an inhibitor of pAKT, strongly blocked the expression of the differentiation markers and p53 and the activation of Notch1. An anti-IL-15 antibody neutralized the effect of IL-15 on KC differentiation. These results indicate that IL-15 inhibits the Ca(2+) -induced differentiation of KCs, mainly via the attenuation of Ca(2+) -stimulated PI3K-AKT signalling.

Genetic variants in five novel loci including CFB and CD40 predispose to chronic hepatitis B.

UNLABELLED: Hepatitis B virus affects more than 2 billion people worldwide, 350 million of which have developed chronic hepatitis B (CHB). The genetic factors that confer CHB risk are still largely unknown. We sought to identify genetic variants for CHB susceptibility in the Chinese population. We undertook a genome-wide association study (GWAS) in 2,514 CHB cases and 1,130 normal controls from eastern China. We replicated 33 of the most promising signals and eight previously reported CHB risk loci through a two-stage validation totaling 6,600 CHB cases and 8,127 controls in four independent populations, of which two populations were recruited from eastern China, one from northern China and one from southern China. The joint analyses of 9,114 CHB cases and 9,257 controls revealed significant association of CHB risk with five novel loci. Four loci are located in the human leukocyte antigen (HLA) region at 6p21.3, including two nonsynonymous variants (rs12614 [R32W] in complement factor B [CFB], Pmeta =1.28 × 10(-34) ; and rs422951 [T320A] in NOTCH4, Pmeta = 5.33 × 10(-16) ); one synonymous variant (rs378352 in HLA-DOA corresponding to HLA-DOA*010101, Pmeta = 1.04 × 10(-23) ); and one noncoding variant (rs2853953 near HLA-C, Pmeta = 5.06 × 10(-20) ). Another locus is located at 20q13.1 (rs1883832 in the Kozak sequence of CD40, Pmeta = 2.95 × 10(-15) ). Additionally, we validated seven of eight previously reported CHB susceptibility loci (rs3130542 at HLA-C, rs1419881 at TCF19, rs652888 at EHMT2, rs2856718 at HLA-DQB1, rs7453920 at HLA-DQB2, rs3077 at HLA-DPA1, and rs9277535 at HLA-DPA2, which are all located in the HLA region, 9.84 × 10(-71) ≤ Pmeta ≤ 9.92 × 10(-7) ). CONCLUSION: Our GWAS identified five novel susceptibility loci for CHB. These findings improve the understanding of CHB etiology and may provide new targets for prevention and treatment of this disease.

Two new susceptibility loci 1q24.2 and 11p11.2 confer risk to severe acne.

Severe acne is a chronic inflammatory skin disorder characterized by widespread inflammatory lesions including nodules, cysts and potential scarring. Here we perform the first genome-wide association study of severe acne in a Chinese Han population comprising 1,056 cases and 1,056 controls using the Illumina HumanOmniZhongHua-8 BeadChip. In an independent cohort of 1,860 cases and 3,660 controls of Chinese Han, we replicate 101 SNPs of which 3 showed consistent association. We identify two new susceptibility loci at 11p11.2 (DDB2, rs747650, P(combined)=4.41 × 10⁻9 and rs1060573, P(combined)=1.28 × 10⁻8) and 1q24.2 (SELL, rs7531806, P(combined)=1.20 × 10⁻8) that are involved in androgen metabolism, inflammation processes and scar formation in severe acne. These results point to new genetic susceptibility factors and suggest several new biological pathways related to severe acne.

EZH2 genetic variants affect risk of gastric cancer in the Chinese Han population.

Enhancer of zeste 2 (EZH2) gene encodes a histone methyltransferase that constitutes the catalytic component of the polycomb repressive complex-2 (PRC2) to initiate epigenetic silencing of genes. It is reported that the expression level of EZH2 in gastric cancer tissue was highly correlated with tumor progression, however, whether EZH2 genetic variants were associated with the risk of gastric cancer remains yet unknown. In this study, we conducted a genotyping analysis for EZH2 in 311 cases of gastric cancer and 425 controls from the Chinese Han population. We found five single nucleotide polymorphisms (SNP; rs12670401, rs6464926, rs2072407, rs734005, and rs734004) of EZH2 gene were significantly associated with the risk of gastric cancer. Of which, the rs12670401 with the minor allele C and rs6464926 with the minor allele T revealed strong associations with increased gastric cancer risk [P = 0.009, adjusted odds ratio (aOR) = 1.327, 95% CI = 1.075-1.683 and P = 0.012, aOR = 1.310, 95% CI = 1.059-1.619]. The other three SNPs, rs2072407, rs734005, and rs734004 contributed to significantly reduced risk of gastric cancer (P = 0.033, aOR = 0.787, 95% CI = 0.633-0.981, P = 0.045, aOR = 0.799, 95% CI = 0.642-0.995 and P = 0.048, aOR = 0.803, 95% CI = 0.645-0.999), respectively. We further found that rs12670401 and rs6464926 were in a strong LD while rs2072407, rs734005, and rs734004 were in another. Haplotype analysis of the five SNPs showed that haplotype CCTCT reduced the risk of gastric cancer (P = 0.031 and aOR = 0.784), while haplotype GTCTC significantly elevated the risk of gastric cancer (P = 0.011 and aOR = 1.310). We concluded that EZH2 variants were significantly associated with gastric cancer risk. Our results for the first time provided new insight into susceptibility factors of EZH2 gene variants in carcinogenesis of gastric cancer of the Chinese Han population.

Variants in TNFSF4, TNFAIP3, TNIP1, BLK, SLC15A4 and UBE2L3 interact to confer risk of systemic lupus erythematosus in Chinese population.

Our previous genome-wide association studies on SLE have identified several susceptibility genes involved in NF-κB signaling pathway, including TNFSF4, TNFAIP3, TNIP1, BLK, SLC15A4 and UBE2L3. The aim of this study is to investigate the association model (additive, dominant, recessive) of these genes and search for possible gene-gene interactions between them. In this study, we explored the association model of these six genes and search for possible gene-gene interactions based on identified single-nucleotide polymorphisms (SNPs) among them by using logistic regression analysis in the combined sample of 4,199 cases and 8,255 controls. The most significant association evidence was observed under recessive model for all of these SNPs. Besides, significant interactions between these SNPs were observed in this study: the TNFSF4 and TNIP1 SNPs (P adjusted = 1.68E-10), the TNFSF4 and SLC15A4 SNPs (P adjusted = 3.55E-08), the TNFSF4 and UBE2L3 SNPs (P adjusted = 8.74E-13), the TNIP1 and BLK SNPs (P adjusted = 9.45E-10), the TNIP1 and UBE2L3 SNPs (P adjusted = 8.25E-11), the TNFAIP3 and UBE2L3 SNPs (P adjusted = 3.06E-14) and the BLK and SLC15A4 SNPs (P adjusted = 4.51E-12). These results may contribute to our understanding of SLE genetic interactions and account for the additional risk of certain patients to develop SLE.

Identification of a missense variant in LNPEP that confers psoriasis risk.

Psoriasis is a chronic inflammatory disease with a complex genetic architecture. To further advance gene discovery, we extended our genome-wide association study data set of 1,139 cases and 2,234 controls and replicated two independent cohorts of 7,200 cases and 10,491 controls. We identified the missense variant rs2303138 (p.Ala763Thr) within the LNPEP gene associated with psoriasis (Pcombined=1.83 × 10(-13), odds ratio=1.16) and validated four previously reported genes: IL28RA, NFKBIA, TRAF3IP2, and CARD14 (9.74 × 10(-11)P9.37 × 10(-5)), which confirmed the involvement of the nuclear factor-κB signaling pathway in psoriasis pathogenesis. LNPEP, also named insulin-responsive aminopeptidase, was identified as an angiotensin IV receptor. Protein function prediction suggested that this missense variant of LNPEP was most likely deleterious. Expression analysis showed that LNPEP was significantly downregulated in psoriatic lesions compared with the control skin (P=1.44 × 10(-6)) and uninvolved patient skin (P=2.95 × 10(-4)). Pathway analysis indicated that LNPEP was involved in the renin-angiotensin system, which also has a key role in cardiovascular disease and diabetes. These results provided genetic evidence that psoriasis might share common mechanisms with hypertension and diabetes, which was consistent with clinical observations. Our study identified a genetic susceptibility factor and provided genetic evidence of insight into psoriasis pathogenesis with the involvement of the renin-angiotensin system pathway.

Association analyses identify three susceptibility Loci for vitiligo in the Chinese Han population.

To identify susceptibility loci for vitiligo, we extended our previous vitiligo genome-wide association study with a two-staged replication study that included 6,857 cases and 12,025 controls from the Chinese Han population. We identified three susceptibility loci, 12q13.2 (rs10876864, P(combined)=8.07 × 10(-12), odds ratio (OR)=1.18), 11q23.3 (rs638893, P(combined)=2.47 × 10(-9), OR=1.22), and 10q22.1 (rs1417210, P(combined)=1.83 × 10(-8), OR=0.88), and confirmed three previously reported loci for vitiligo, 3q28 (rs9851967, P(combined)=8.57 × 10(-8), OR=0.88), 10p15.1 (rs3134883, P(combined)=1.01 × 10(-5), OR=1.11), and 22q12.3 (rs2051582, P(combined)=2.12 × 10(-5), OR=1.14), in the Chinese Han population. The most significant single-nucleotide polymorphism in the 12q13.2 locus is located immediately upstream of the promoter region of PMEL, which encodes a major melanocyte antigen and has expression loss in the vitiligo lesional skin. In addition, both 12q13.2 and 11q23.3 loci identified in this study are also associated with other autoimmune diseases such as type 1 diabetes and systemic lupus erythematosus. These findings provide indirect support that vitiligo pathogenesis involves a complex interplay between immune regulatory factors and melanocyte-specific factors. They also highlight similarities and differences in the genetic basis of vitiligo in Chinese and Caucasian populations.

Genetic variants in STAT4 and HLA-DQ genes confer risk of hepatitis B virus-related hepatocellular carcinoma.

To identify genetic susceptibility loci for hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in the Chinese population, we carried out a genome-wide association study (GWAS) in 2,514 chronic HBV carriers (1,161 HCC cases and 1,353 controls) followed by a 2-stage validation among 6 independent populations of chronic HBV carriers (4,319 cases and 4,966 controls). The joint analyses showed that HCC risk was significantly associated with two independent loci: rs7574865 at STAT4, P(meta) = 2.48 × 10(-10), odds ratio (OR) = 1.21; and rs9275319 at HLA-DQ, P(meta) = 2.72 × 10(-17), OR = 1.49. The risk allele G at rs7574865 was significantly associated with lower mRNA levels of STAT4 in both the HCC tissues and nontumor tissues of 155 individuals with HBV-related HCC (P(trend) = 0.0008 and 0.0002, respectively). We also found significantly lower mRNA expression of STAT4 in HCC tumor tissues compared with paired adjacent nontumor tissues (P = 2.33 × 10(-14)).

Exome sequencing identifies a COL14A1 mutation in a large Chinese pedigree with punctate palmoplantar keratoderma.

BACKGROUND: Punctate palmoplantar keratoderma (PPPK) is a rare autosomal dominant skin disorder characterised by numerous hyperkeratotic papules irregularly distributed on the palms and soles. To date, no causal gene for this disease has been identified. METHODS: We performed exome sequencing analysis of four affected individuals and two unaffected controls from one Chinese PPPK family where disease locus was mapped at 8q24.13-8q24.21 by our previous linkage analysis. RESULTS: We identified a novel heterozygous mutation in COL14A1 gene (c.4505C→T (p.Pro1502Leu)), which located within the linkage region that we previously identified for PPPK. The mutation was shared by the four affected individuals, but not for the two controls of the family. Sanger sequencing confirmed this mutation in another four cases from this family. This mutation was invisible in the normal controls of this family as well as the additional 676 unrelated normal controls and 781 patients with other disease. The shared COL14A1 mutation, p.Pro1502Leu, is a missense substitution at a highly conserved amino acid residue across multiple species. CONCLUSIONS: The power of combining exome sequencing and linkage information in the study of genetics of autosomal dominant disorders, even in simplex cases, has been demonstrated. Our results suggested that COL14A1 would be a casual gene for PPPK, which was helpful for advancing us on understanding of the pathogenesis of PPPK.

Genotypic variants at 2q33 and risk of esophageal squamous cell carcinoma in China: a meta-analysis of genome-wide association studies.

Genome-wide association studies have identified susceptibility loci for esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis of all single-nucleotide polymorphisms (SNPs) that showed nominally significant P-values in two previously published genome-wide scans that included a total of 2961 ESCC cases and 3400 controls. The meta-analysis revealed five SNPs at 2q33 with P< 5 × 10(-8), and the strongest signal was rs13016963, with a combined odds ratio (95% confidence interval) of 1.29 (1.19-1.40) and P= 7.63 × 10(-10). An imputation analysis of 4304 SNPs at 2q33 suggested a single association signal, and the strongest imputed SNP associations were similar to those from the genotyped SNPs. We conducted an ancestral recombination graph analysis with 53 SNPs to identify one or more haplotypes that harbor the variants directly responsible for the detected association signal. This showed that the five SNPs exist in a single haplotype along with 45 imputed SNPs in strong linkage disequilibrium, and the strongest candidate was rs10201587, one of the genotyped SNPs. Our meta-analysis found genome-wide significant SNPs at 2q33 that map to the CASP8/ALS2CR12/TRAK2 gene region. Variants in CASP8 have been extensively studied across a spectrum of cancers with mixed results. The locus we identified appears to be distinct from the widely studied rs3834129 and rs1045485 SNPs in CASP8. Future studies of esophageal and other cancers should focus on comprehensive sequencing of this 2q33 locus and functional analysis of rs13016963 and rs10201587 and other strongly correlated variants.

A genome-wide association study in Han Chinese identifies multiple susceptibility loci for IgA nephropathy.

We performed a two-stage genome-wide association study of IgA nephropathy (IgAN) in Han Chinese, with 1,434 affected individuals (cases) and 4,270 controls in the discovery phase and follow-up of the top 61 SNPs in an additional 2,703 cases and 3,464 controls. We identified associations at 17p13 (rs3803800, P = 9.40 × 10(-11), OR = 1.21; rs4227, P = 4.31 × 10(-10), OR = 1.23) and 8p23 (rs2738048, P = 3.18 × 10(-14), OR = 0.79) that implicated the genes encoding tumor necrosis factor (TNFSF13) and α-defensin (DEFA) as susceptibility genes. In addition, we found multiple associations in the major histocompatibility complex (MHC) region (rs660895, P = 4.13 × 10(-20), OR = 1.34; rs1794275, P = 3.43 × 10(-13), OR = 1.30; rs2523946, P = 1.74 × 10(-11), OR = 1.21) and confirmed a previously reported association at 22q12 (rs12537, P = 1.17 × 10(-11), OR = 0.78). We also found that rs660895 was associated with clinical subtypes of IgAN (P = 0.003), proteinuria (P = 0.025) and IgA levels (P = 0.047). Our findings show that IgAN is associated with variants near genes involved in innate immunity and inflammation.

A single-nucleotide polymorphism of the TNFSF4 gene is associated with systemic lupus erythematosus in Chinese Han population.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with complex genetic inheritance. Recently, single-nucleotide polymorphisms (SNPs) in tumor necrosis factor (TNF) superfamily gene TNFSF4 have been shown to be associated with SLE in European and Hong Kong Chinese populations. But it is unknown whether it is also associated with the disease in Mainland Chinese Han population. We genotyped the SNPs rs1234315 near the TNFSF4 gene in 1,344 SLE patients and 4,315 controls of Chinese Han population and confirmed the association between the SNP and the SLE [odds ratios (ORs) of 1.45 and P values of 1.5 × 10(-16)]. The stratification analyses showed that rs1234315 was more strongly associated with SLE patients with arthritis. Our study not only suggested that the TNFSF4 gene was associated with SLE in Chinese Han population, but also implied that it might be a common genetic factor predisposing to the development of SLE in multiple populations.

Association analyses identify six new psoriasis susceptibility loci in the Chinese population.

We extended our previous genome-wide association study for psoriasis with a multistage replication study including 8,312 individuals with psoriasis (cases) and 12,919 controls from China as well as 3,293 cases and 4,188 controls from Germany and the United States and 254 nuclear families from the United States. We identified six new susceptibility loci associated with psoriasis in the Chinese study containing the candidate genes ERAP1, PTTG1, CSMD1, GJB2, SERPINB8 and ZNF816A (combined P < 5 × 10⁻8) and replicated one locus, 5q33.1 (TNIP1-ANXA6), previously reported (combined P = 3.8 × 10⁻²¹) in the European studies. Two of these loci showed evidence for association in the German study at ZNF816A and GJB2 with P = 3.6 × 10⁻³ and P = 7.9 × 10⁻³, respectively. ERAP1 and ZNF816A were associated with type 1 (early onset) psoriasis in the Chinese Han population (test for heterogeneity P = 6.5 × 10⁻³ and P = 1.5 × 10⁻³, respectively). Comparisons with the results of previous GWAS of psoriasis highlight the heterogeneity of disease susceptibility between the Chinese and European populations. Our study identifies new genetic susceptibility factors and suggests new biological pathways in psoriasis.

Genome-wide association study of esophageal squamous cell carcinoma in Chinese subjects identifies susceptibility loci at PLCE1 and C20orf54.

We performed a genome-wide association study of esophageal squamous cell carcinoma (ESCC) by genotyping 1,077 individuals with ESCC and 1,733 control subjects of Chinese Han descent. We selected 18 promising SNPs for replication in an additional 7,673 cases of ESCC and 11,013 control subjects of Chinese Han descent and 303 cases of ESCC and 537 control subjects of Chinese Uygur-Kazakh descent. We identified two previously unknown susceptibility loci for ESCC: PLCE1 at 10q23 (P(Han combined for ESCC) = 7.46 x 10(-56), odds ratio (OR) = 1.43; P(Uygur-Kazakh for ESCC) = 5.70 x 10(-4), OR = 1.53) and C20orf54 at 20p13 (P(Han combined for ESCC) = 1.21 x 10(-11), OR = 0.86; P(Uygur-Kazakh for ESCC) = 7.88 x 10(-3), OR = 0.66). We also confirmed association in 2,766 cases of gastric cardia adenocarcinoma cases and the same 11,013 control subjects (PLCE1, P(Han for GCA) = 1.74 x 10(-39), OR = 1.55 and C20orf54, P(Han for GCA) = 3.02 x 10(-3), OR = 0.91). PLCE1 and C20orf54 have important biological implications for both ESCC and GCA. PLCE1 might regulate cell growth, differentiation, apoptosis and angiogenesis. C20orf54 is responsible for transporting riboflavin, and deficiency of riboflavin has been documented as a risk factor for ESCC and GCA.

A single-nucleotide polymorphism of the TNFAIP3 gene is associated with systemic lupus erythematosus in Chinese Han population.

Systemic lupus erythematosus (SLE) is a complex systemic disease influenced by genetic and environmental factors. The exact pathogenesis of SLE is still unknown. Recently, several genome-wide association studies (GWA) in European population have found many novel susceptibility genes for SLE including TNFAIP3. In order to examine whether TNFAIP3 is associated with SLE in Chinese Han population, we genotyped one of its non-synonymous mutation SNP rs2230926, showing significant association evidence with SLE in European population, with 1,420 cases and 4,461 controls of Chinese Han by using Sequenom MassArray system. Highly significant association between SNP rs2230926 and SLE of Chinese Han was detected [OR = 1.65, 95% confidence interval (CI): 1.392-1.986, P = 2.03 x 10(-8)]. Interestingly, rs2230926 of TNFAIP3 was also associated with arthritis, ANA and some other subphenotypes of the disease. Our findings suggest that SNP rs2230926 in the TNFAIP3 might be a common genetic factor for SLE within different populations in terms of Chinese Han and European population.

Genetic diagnosis in a Chinese Hailey-Hailey disease pedigree with novel ATP2C1 gene mutation.

Hailey-Hailey disease (HHD) is an autosomal dominant skin disorder characterized by recurrent eruption of vesicles and bullae at the sites of friction and in the intertriginous areas. Mutations in the ATP2C1 gene encoding the human secretory pathway calcium ATPase 1 (hSPCA1) have been identified as the causative mutations in HHD. In this study, we used direct sequencing and restriction endonuclease digestion to analyze mutations of the ATP2C1 gene in a Chinese three-generation pedigree. A heterozygous T-to-C transition at nucleotide 1004 in exon 12 of ATP2C1 gene was detected. After summarizing the reported cases with ATP2C1 mutation, we concluded that the T1004C transition resulted in a novel missense mutation of leucine condon (CTG) to proline (CCG) at amino acid residue 335(L335P) in hSPCA1. Here, a genetic diagnosis was made for the proband's daughter before the clinical presentation. The study realized the molecular diagnosis in the HHD pedigree. Our findings should be useful for genetic counseling and prenatal diagnosis for the affected family and in demonstrating the critical role of the ATP2C1 gene in the pathogenesis of HHD further.