Fei-Yan Deng

Multistage genome-wide association meta-analyses identified two new loci for bone mineral density

Aiming to identify novel genetic variants and to confirm previously identified genetic variants associated with bone mineral density (BMD), we conducted a three-stage genome-wide association (GWA) meta-analysis in 27 061 study subjects. Stage 1 meta-analyzed seven GWA samples and 11 140 subjects for BMDs at the lumbar spine, hip and femoral neck, followed by a Stage 2 in silico replication of 33 SNPs in 9258 subjects, and by a Stage 3 de novo validation of three SNPs in 6663 subjects. Combining evidence from all the stages, we have identified two novel loci that have not been reported previously at the genome-wide significance (GWS; 5.0 × 10(-8)) level: 14q24.2 (rs227425, P-value 3.98 × 10(-13), SMOC1) in the combined sample of males and females and 21q22.13 (rs170183, P-value 4.15 × 10(-9), CLDN14) in the female-specific sample. The two newly identified SNPs were also significant in the GEnetic Factors for OSteoporosis consortium (GEFOS, n = 32 960) summary results. We have also independently confirmed 13 previously reported loci at the GWS level: 1p36.12 (ZBTB40), 1p31.3 (GPR177), 4p16.3 (FGFRL1), 4q22.1 (MEPE), 5q14.3 (MEF2C), 6q25.1 (C6orf97, ESR1), 7q21.3 (FLJ42280, SHFM1), 7q31.31 (FAM3C, WNT16), 8q24.12 (TNFRSF11B), 11p15.3 (SOX6), 11q13.4 (LRP5), 13q14.11 (AKAP11) and 16q24 (FOXL1). Gene expression analysis in osteogenic cells implied potential functional association of the two candidate genes (SMOC1 and CLDN14) in bone metabolism. Our findings independently confirm previously identified biological pathways underlying bone metabolism and contribute to the discovery of novel pathways, thus providing valuable insights into the intervention and treatment of osteoporosis.

Peripheral Blood Monocyte-expressed ANXA2 Gene is Involved in Pathogenesis of Osteoporosis in Humans

Low bone mineral density (BMD) is a risk factor of osteoporosis and has strong genetic determination. Genes influencing BMD and fundamental mechanisms leading to osteoporosis have yet to be fully determined. Peripheral blood monocytes (PBM) are potential osteoclast precursors, which could access to bone resorption surfaces and differentiate into osteoclasts to resorb bone. Herein, we attempted to identify osteoporosis susceptibility gene(s) and characterize their function(s), through an initial proteomics discovery study on PBM in vivo, and multiscale validation studies in vivo and in vitro. Utilizing the quantitative proteomics methodology LC-nano-ESI-MSE, we discovered that a novel protein, i.e. ANXA2, was up-regulated twofold in PBM in vivo in Caucasians with extremely low BMD (cases) versus those with extremely high BMD (controls) (n = 28, p < 0.05). ANXA2 gene up-regulation in low BMD subjects was replicated at the mRNA level in PBM in vivo in a second and independent case-control sample (n = 80, p < 0.05). At the DNA level, we found that SNPs in the ANXA2 gene were associated with BMD variation in a 3rd and independent case-control sample (n = 44, p < 0.05), as well as in a random population sample (n = 997, p < 0.05). The above integrative evidence strongly supports the concept that ANXA2 is involved in the pathogenesis of osteoporosis in humans. Through a follow-up cellular functional study, we found that ANXA2 protein significantly promoted monocyte migration across an endothelial barrier in vitro (p < 0.001). Thus, elevated ANXA2 protein expression level, as detected in low BMD subjects, probably stimulates more PBM migration through the blood vessel walls to bone resorption surfaces in vivo, where they differentiate into higher number of osteoclasts and resorb bone at higher rates, thereby decreasing BMD. In conclusion, this study identified a novel osteoporosis susceptibility gene ANXA2, and suggested a novel pathophysiological mechanism, mediated by ANXA2, for osteoporosis in humans.

Pharmacogenetics and pharmacogenomics for rheumatoid arthritis responsiveness to methotrexate treatment: the 2013 update

Rheumatoid arthritis (RA) is a complex, systemic autoimmune disease characterized by chronic inflammation of multiple peripheral joints, which leads to serious destruction of cartilage and bone, progressive deformity and severe disability. Methotrexate (MTX) is one of the first-line drugs commonly used in RA therapy owing to its excellent long-term efficacy and cheapness. However, the efficacy and toxicity of MTX treatment have significant interpatient variability. Genetic factors contribute to this variability. In this review, we have summarized and updated the progress of RA response to MTX treatment since 2009 by focusing on the fields of pharmacogenetics and pharmacogenomics. Identification of genetic factors involved in MTX treatment response will increase the understanding of RA pathology and the development of new personalized treatments.

Meta-analysis of Atherogenic Index of Plasma and other lipid parameters in relation to risk of type 2 diabetes mellitus

AIMS Diabetic dyslipidemia is one of important complication of type 2 diabetes mellitus (T2DM). Blood lipid parameters (e.g., triglyceride, TG; total cholesterol, TC; high-density lipoprotein cholesterol, HDL-C; low-density lipoprotein cholesterol, LDL-C; Atherogenic Index of Plasma defined as lg(TG/HDL-C), AIP), are important indexes in predicting risk of T2DM. This study performed comprehensive meta-analyses to evaluate the powers of these indexes, especially for AIP, on predicting risk of T2DM. METHODS We searched PubMed Database, China National Knowledge Infrastructure (CNKI) and Wanfang Database in February 2014 to identify eligible studies. Case-control studies that have mean baseline values of AIP were included. Random-effect models were used to pool the summary standardized mean difference (SMD) in meta-analysis. RESULTS Fifteen eligible studies, with a total sample size of 4010, were included in meta-analysis. All these studies reported positive associations between AIP and T2DM. Moreover, the SMD for the AIP is 1.78 (95% confidence interval (CI): 1.04-2.52), which is higher than for other parameters (TG: 0.93, 95% CI: 0.78-1.09; TC: 0.46, 95% CI: 0.21-0.71; HDL-C: -0.89, 95% CI: -1.18 to -0.60; and LDL-C: 0.44, 95% CI: 0.11-0.77). Meta-analysis of association between BMI and T2DM gave a SMD of 0.85 (95% CI: 0.38 to 1.32). CONCLUSIONS The results suggest that lipid parameters have ability to reflect the risk of T2DM, but AIP may be more closely associated with the risk of T2DM. The current results suggest AIP may be used as a simple, easily calculated parameter in assessing the risk of T2DM.

An Integrative Study Ascertained SOD2 as a Susceptibility Gene for Osteoporosis in Chinese

Osteoporosis is characterized by low BMD and has strong genetic determination. However, specific genetic variants influencing BMD and contributing to the pathogenesis of osteoporosis are largely uncharacterized. Current genetic studies in bone, which are aimed at identification of osteoporosis risk genes, are focused mostly on DNA, RNA, or the protein level individually, lacking integrative evidence from the three levels of genetic information flow to confidently ascertain the significance of genes for osteoporosis. Our previous proteomics study discovered that superoxide dismutase 2 (SOD2) in circulating monocytes (CMCs, ie, potential osteoclast precursors) was significantly upregulated at protein level in vivo in Chinese with low versus high hip BMD. Herein, at mRNA level, we found that SOD2 gene expression also was upregulated in CMCs (p < 0.05) in Chinese with low versus high hip BMD. At the DNA level, in 1627 unrelated Chinese subjects, we identified eight single‐nucleotide polymorphisms (SNPs) at the SOD2 gene locus that were suggestively associated with hip BMD (peak signal at rs11968525, p = 0.048). Among the eight SNPs, three SNPs (rs7754103, rs7754295, and rs2053949) were associated with the SOD2 mRNA expression level (p < 0.05), suggesting that they are expression quantitative trait loci (eQTLs) regulating SOD2 gene expression. In conclusion, this integrative evidence from DNA, RNA, and protein levels support SOD2 as a susceptibility gene for osteoporosis.

Identification of novel risk genes associated with type 1 diabetes mellitus using a genome-wide gene-based association analysis.

Type 1 diabetes mellitus is a serious disorder characterized by destruction of pancreatic β‐cells, culminating in absolute insulin deficiency. Genetic factors contribute to the susceptibility of type 1 diabetes mellitus. The aim of the present study was to identify more susceptibility genes of type 1 diabetes mellitus.

Copy Number Variation on Chromosome 10q26.3 for Obesity Identified by a Genome-Wide Study

BACKGROUND Obesity is a highly heritable disease defined by high body mass index (BMI). However, a large proportion of the heritability of obesity remains unexplained. Copy number variations (CNVs) might contribute to the missing heritability of obesity. METHODS We conducted genome-wide CNV analyses on obesity phenotypes, including BMI and body fat mass in a discovery sample of 2215 unrelated white subjects. After quality control, 314 CNVs were used for association tests. For significant CNVs identified, follow-up replication analyses were performed in three independent samples, including an unrelated sample of 1000 white subjects (OM sample), a family-based sample of 8385 white subjects (FHS sample), and an African-American sample of 1479 obesity cases and 1575 lean controls (AA sample). RESULTS Genome-wide CNV analyses detected that a CNV located at 10q26.3, which, even after multiple testing corrections, showed a strong association with both BMI (P = 2.30 × 10(-4), β = 2.164) and body fat mass (P = 6.76 × 10(-5), β = 4.126). This CNV was successfully replicated in the three replication samples (OM sample: P = 0.0465 for BMI, 0.0435 for fat mass; FHS sample: P = 0.0038 for BMI; AA sample: P = 0.0023 for obesity). Quantitative PCR validated this CNV, which covers a gene, CYP2E1. The protein encoded by CYP2E1 involves the synthesis of cholesterol, steroids and other lipids, which may have a potential impact on obesity. CONCLUSION Our findings suggest the significant contribution of CNV10q26.3 to the pathogenesis of obesity.

SNP rs6265 Regulates Protein Phosphorylation and Osteoblast Differentiation and Influences BMD in Humans

Bone mineral density (BMD) is a major index for diagnosing osteoporosis. PhosSNPs are nonsynonymous SNPs that affect protein phosphorylation. The relevance and significance of phosSNPs to BMD and osteoporosis is unknown. This study aimed to identify and characterize phosSNPs significant for BMD in humans. We conducted a pilot genomewide phosSNP association study for BMD in three independent population samples, involving ∼5000 unrelated individuals. We identified and replicated three phosSNPs associated with both spine BMD and hip BMD in Caucasians. Association with hip BMD for one of these phosSNPs, ie, rs6265 (major/minor allele: G/A) in BDNF gene, was also suggested in Chinese. Consistently in both ethnicities, individuals carrying the AA genotype have significantly lower hip BMD than carriers of the GA and GG genotypes. Through in vitro molecular and cellular studies, we found that compared to osteoblastic cells transfected with wild‐type BDNF‐Val66 (encoded with allele G at rs6265), transfection of variant BDNF‐Met66 (encoded with allele A at rs6265) significantly decreased BDNF protein phosphorylation (at amino acid residue T62), expression of osteoblastic genes (OPN, BMP2, and ALP), and osteoblastic activity. The findings are consistent with and explain our prior observations in general human populations. We conclude that phosSNP rs6265, by regulating BDNF protein phosphorylation and osteoblast differentiation, influences hip BMD in humans. This study represents our first endeavor to dissect the functions of phosSNPs in bone, which might stimulate extended large‐scale studies on bone or similar studies on other human complex traits and diseases.

Network-based proteomic analysis for postmenopausal osteoporosis in Caucasian females.

Menopause is one of the crucial physiological events during the life of a woman. Transition of menopause status is accompanied by increased risks of various health problems such as osteoporosis. Peripheral blood monocytes can differentiate into osteoclasts and produce cytokines important for osteoclast activity. With quantitative proteomics LC‐nano‐ESI‐MSE (where MSE is elevated‐energy MS), we performed protein expression profiling of peripheral blood monocytes in 42 postmenopausal women with discordant bone mineral density (BMD) levels. Traditional comparative analysis showed proteins encoded by four genes (LOC654188, PPIA, TAGLN2, YWHAB) and three genes (LMNB1, ANXA2P2, ANXA2) were significantly down‐ and upregulated, respectively, in extremely low‐ versus high‐BMD subjects. To study functionally orchestrating groups of detected proteins in the form of networks, we performed weighted gene coexpression network analysis and gene set enrichment analysis. Weighted gene coexpression network analysis showed that the module including the annexin gene family was most significantly correlated with low BMD, and the lipid‐binding related GO terms were enriched in this identified module. Gene set enrichment analysis revealed that two significantly enriched gene sets may be involved in postmenopausal BMD variation by regulating pro‐inflammatory cytokines activities. To gain more insights into the proteomics data generated, we performed integrative analyses of the datasets available to us at the genome (DNA level), transcriptome (RNA level), and proteome levels jointly.

Is GSN Significant for Hip BMD in Female Caucasians

Low bone mineral density (BMD) is a risk factor for osteoporosis. Osteoporosis is more prevalent in females than in males. So far, the pathophysiological mechanisms underlying osteoporosis are unclear. Peripheral blood monocytes (PBMs) are precursors of bone-resorbing osteoclasts. This study aims to identify PBM-expressed proteins (genes) influencing hip BMD in humans. We utilized three independent study cohorts (N=34, 29, 40), including premenopausal Caucasians with discordant hip BMD. We studied PBM proteome-wide protein expression profiles in cohort 1 and identified 57 differentially expressed proteins (DEPs) between low vs. high BMD subjects. One protein gelsolin (GSN), after validation by Western blotting, was subject to follow-up. We compared GSN mRNA level in PBM between low vs. high BMD subjects in cohorts 2 and 3. We genotyped SNPs across GSN in 2286 unrelated Caucasians (cohort 4) and 1627 Chinese (cohort 5) and tested their association with hip BMD in females and males, respectively. We discovered and validated that GSN protein expression level in PBM was down-regulated 3.0-fold in low vs. high BMD subjects (P<0.05). Down-regulation of GSN in PBM in low BMD subjects was also observed at mRNA level in both cohort 2 and cohort 3. We identified that SNP rs767770 was significantly associated with hip BMD in female Caucasians (P=0.0003) only. Integrating analyses of the datasets at DNA, RNA, and protein levels from female Caucasians substantiated that GSN is highly significant for hip BMD (P=0.0001). We conclude that GSN is a significant gene influencing hip BMD in female Caucasians.