CER1 gene variations associated with bone mineral density, bone markers, and early menopause in postmenopausal women

The regulation of methylation on the Z chromosome and the identification of multiple novel Male Hyper-Methylated regions in the chicken

DNA methylation is a key regulator of eukaryote genomes, and is of particular relevance in the regulation of gene expression on the sex chromosomes, with a key role in dosage compensation in mammalian XY systems. In the case of birds, dosage compensation is largely absent, with it being restricted to two small Male Hyper-Methylated (MHM) regions on the Z chromosome. To investigate how variation in DNA methylation is regulated on the Z chromosome we utilised a wild x domestic advanced intercross in the chicken, with both hypothalamic methylomes and transcriptomes assayed in 124 individuals. The relatively large numbers of individuals allowed us to identify additional genomic MHM regions on the Z chromosome that were significantly differentially methylated between the sexes. These regions appear to down-regulate local gene expression in males, but not remove it entirely (unlike the lncRNAs identified in the initial MHM regions). These MHM regions were further tested and the most balanced genes appear to show decreased expression in males, whilst methylation appeared to be far more correlated with gene expression in the less balanced, as compared to the most balanced genes. In addition, quantitative trait loci (QTL) that regulate variation in methylation on the Z chromosome, and those loci that regulate methylation on the autosomes that derive from the Z chromosome were mapped. Trans-effect hotspots were also identified that were based on the autosomes but affected the Z, and also one that was based on the Z chromosome but that affected both autosomal and sex chromosome DNA methylation regulation. We show that both cis and trans loci that originate from the Z chromosome never exhibit an interaction with sex, whereas trans loci originating from the autosomes but affecting the Z chromosome always display such an interaction. Our results highlight how additional MHM regions are actually present on the Z chromosome, and they appear to have smaller-scale effects on gene expression in males. Quantitative variation in methylation is also regulated both from the autosomes to the Z chromosome, and from the Z chromosome to the autosomes.

Association of Early Childhood Caries with Bitter Taste Receptors: A Meta-Analysis of Genome-Wide Association Studies and Transcriptome-Wide Association Study

Although genetics affects early childhood caries (ECC) risk, few studies have focused on finding its specific genetic determinants. Here, we performed genome-wide association studies (GWAS) in five cohorts of children (aged up to 5 years, total N = 2974, cohorts: Center for Oral Health Research in Appalachia cohorts one and two [COHRA1, COHRA2], Iowa Fluoride Study, Iowa Head Start, Avon Longitudinal Study of Parents and Children [ALSPAC]) aiming to identify genes with potential roles in ECC biology. We meta-analyzed the GWASs testing ~3.9 million genetic variants and found suggestive evidence for association at genetic regions previously associated with caries in primary and permanent dentition, including the β-defensin anti-microbial proteins. We then integrated the meta-analysis results with gene expression data in a transcriptome-wide association study (TWAS). This approach identified four genes whose genetically predicted expression was associated with ECC (p-values < 3.09 × 10−6; CDH17, TAS2R43, SMIM10L1, TAS2R14). Some of the strongest associations were with genes encoding members of the bitter taste receptor family (TAS2R); other members of this family have previously been associated with caries. Of note, we identified the receptor encoded by TAS2R14, which stimulates innate immunity and anti-microbial defense in response to molecules released by the cariogenic bacteria, Streptococcus mutans and Staphylococcus aureus. These findings provide insight into ECC genetic architecture, underscore the importance of host-microbial interaction in caries risk, and identify novel risk genes.

Genotypic Analyses of the Sclerostin rs851056 and Dickkopf rs1569198 Polymorphisms in Mexican-Mestizo Postmenopausal Osteoporosis: A Case-Control Study

Background: The Wnt/β catenin pathway promotes bone mineralization stimulating proliferation, differentiation, and survival of osteoblasts; it also inhibits osteoclast differentiation and osteocyte activity. Sclerostin (SOST) and Dickkopf 1 (DKK1) are Wnt/β catenin pathway inhibitors. Genetic variability in the expression of SOST and DKK1 might be involved in the development of postmenopausal osteoporosis (OP). Aim: To determine whether the SOST rs851056 and DKK1 rs1569198 polymorphisms are associated with OP in Mexican-Mestizo postmenopausal women. Materials and Methods: Two hundred and eighty Mexican-Mestizo postmenopausal women were assessed for their bone mineral density by dual-energy X-ray absorptiometry (DXA). Patients were classified as OP or non-OP. Genomic DNA was extracted from peripheral blood leukocytes. Genetic polymorphisms were analyzed by quantitative polymerase chain reaction using TaqMan probes. Results: The frequency of OP was 40% among the study population. Osteoporotic patients were older (p < 0.001), had a higher frequency of smoking (p = 0.01), and lower body mass index (p < 0.001) compared with the non-osteoporotic patients. The genotypic frequencies of the rs851056 locus of the SOST gene were GG 19%, GC 45%, and CC 35%, whereas the genotypic frequencies of the rs1569198 locus of the DKK1 gene were GG 15%, GA 40%, and AA 44%. In relation to rs851056 locus of the SOST gene, no differences were observed between the OP and non-OP cohorts in the frequencies of the GC polymorphism (48.7% vs. 43.1%). Similarly, analyses of the DKK1 rs1569198 does not demonstrate differences in the GA genotypic frequencies between the OP and non-OP cohorts (42.5% vs. 38.9%). Conclusion: Polymorphisms SOST rs851056 and DKK1 rs1569198 polymorphisms are not associated with OP in Mexican-Mestizo postmenopausal women.

The Clinical Diagnostic and Prognostic Value of Dickkopf-1 in Cancer

The Wnt signaling pathway extensively participates in diverse processes such as embryonic development, maintenance of homeostasis and tumor pathogenesis. Dickkopf-1 (DKK1), a Wnt inhibitor, plays a vital role for over the past decades regarding its role in the regulation of several types of cancers. However, studies have shown that DKK1 is expressed differently in cancer and plays a role as a cancer-promoting factor or a tumor suppressor, which is worthy of further exploration. We herein study whether DKK1 is highly expressed in all cancers and plays a crucial role in promoting cancer. Furthermore, we discussed as to which stages of cancer development it plays in. Finally, the present detection methods were introduced and indicated the clinical application of DKK1 in tumor development.

Common and rare variants of WNT16, DKK1 and SOST and their relationship with bone mineral density

Numerous GWAS and candidate gene studies have highlighted the role of the Wnt pathway in bone biology. Our objective has been to study in detail the allelic architecture of three Wnt pathway genes: WNT16, DKK1 and SOST, in the context of osteoporosis. We have resequenced the coding and some regulatory regions of these three genes in two groups with extreme bone mineral density (BMD) (n = ∼50, each) from the BARCOS cohort. No interesting novel variants were identified. Thirteen predicted functional variants have been genotyped in the full cohort (n = 1490), and for ten of them (with MAF > 0.01), the association with BMD has been studied. We have found six variants nominally associated with BMD, of which 2 WNT16 variants predicted to be eQTLs for FAM3C (rs55710688, in the Kozak sequence and rs142005327, within a putative enhancer) withstood multiple-testing correction. In addition, two rare variants in functional regions (rs190011371 in WNT16b 3′UTR and rs570754792 in the SOST TATA box) were found only present in three women each, all with BMD below the mean of the cohort. Our results reinforce the higher importance of regulatory versus coding variants in these Wnt pathway genes and open new ways for functional studies of the relevant variants.

Dickkopf 1 protein circulating levels as a possible biomarker of functional disability and chronic damage in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease characterized by joint destruction, deformity, lower functionality, and decrease in life expectancy. Wingless signaling pathway (Wnt) has been recently involved in bone homeostasis. Studies suggest that overexpression of the pathway inhibitors, like the Dickkopf 1 protein (DKK1), has been implicated in bone destruction. The objective of this study is to compare circulating levels of DKK1 in different groups of patients with disease activity (remission, low, moderate, high activity,) and functionality status. Three hundred seventy-nine patients with RA were evaluated between March 2015 and November 2016. Disease activity was evaluated by disease activity score 28 with C-reactive protein (DAS28CPR), simplified and clinical disease activity scores (SDAI, CDAI), routine assessment of patient index data 3 (RAPID3), functional status using Multidimensional Health Assessment Questionnaire (MD-HAQ), and the Steinbrocker functional classification. DKK1 levels were measured by ELISA. The mean age was 60.7 ± 13.9 years. Disease duration was 13.2 ± 10.9 years. Higher levels of DKK1 were not associated with disease activity by CDAI (p = 0.70), SDAI (p = 0.84), DAS28CRP (p = 0.80), or RAPID3 (p = 0.70). Interestingly higher levels of DKK1 were significantly associated to lower functional status evaluating by the Steinbrocker classification (p = 0,013), severe disability by MD-HAQ (p = 0,004), and variables associated with joint destruction like osteoporosis, higher titles of rheumatoid factor, smoking, and increased hospital admissions related to RA. Higher levels of DKK1 were found in patients with lower functional status. This association was not found in patients with greater disease activity by CDAI, SDAI, DAS28, and RAPID3. This could be explained by more structural damage; DKK1 could be used as a biomarker of joint destruction in RA.

New Ligand Binding Function of Human Cerberus and Role of Proteolytic Processing in Regulating Ligand-Receptor Interactions and Antagonist Activity

Cerberus is a key regulator of vertebrate embryogenesis. Its biological function has been studied extensively in frog and mouse embryos. Its ability to bind and antagonize the transforming growth factor-β (TGF-β) family ligand Nodal is well established. Strikingly, the molecular function of Cerberus remains poorly understood. The underlying reason is that Cerberus is a complex, multifunctional protein: It binds and inhibits multiple TGF-β family ligands, it may bind and inhibit some Wnt family members, and two different forms with distinct activities have been described. In addition, sequence homology between frog and mammalian Cerberus is low, suggesting that previous studies, which analyzed frog Cerberus function, may not accurately describe the function of mammalian Cerberus. We therefore undertook to determine the molecular activities of human Cerberus in TGF-β family signaling. Using purified proteins, surface plasmon resonance, and reporter gene assays, we discovered that human Cerberus bound and inhibited the TGF-β family ligands Activin B, BMP-6, and BMP-7, but not the frog Cerberus ligand BMP-2. Notably, full-length Cerberus successfully blocked ligand binding to type II receptors, but the short form was less effective. In addition, full-length Cerberus suppressed breast cancer cell migration but the short form did not. Thus, our findings expand the roles of Cerberus as TGF-β family signaling inhibitor, provide a molecular rationale for the function of the N-terminal region, and support the idea that Cerberus could have regulatory activities beyond direct inhibition of TGF-β family signaling.

Analysis of the Influence of Hormone Replacement Therapy on Osteocalcin Gene Expression in Postmenopausal Women

Background. Osteocalcin (OC) contributes to the process of bone mineralization. Present study was designed to investigate the changes in OC gene expression of postmenopausal women treated with hormone replacement therapy (HRT). Study was also designed to evaluate OC gene expression in cells which are not part of connective tissue. Material and Methods. Research was carried out on 30 postmenopausal women not treated and 30 treated with HRT. Examination of OC gene expression was conducted on peripheral blood lymphocytes (PBL) and buccal epithelial lining (BEL). Densitometry was conducted on femur and mandible. Results. Tests revealed OC gene expression in BEL and PBL. BMD was higher in groups treated with HRT. Assessment of correlation between the OC gene expression in BEL and BMD of mandible revealed significant positive relation. Conclusions. OC gene expression can be stated BEL and PBL. Analysis of correlation between OC gene expression in oral cavity and mandible BMD showed significant correlation between local OC expression and local bone metabolism. The relation between OC gene expression and bone metabolism is complex and further research is needed to clear all of the uncertainties.

Influence of polymorphisms in insulin-like growth factor-1 on the risk of osteoporosis in a Chinese postmenopausal female population

We conducted a case-control study in a Chinese postmenopausal population, and explore the potential role of the promoter region variation of the IGF-1 gene in bone mineral density and osteoporosis risk. 485 postmenopausal women with a primary diagnosis of osteoporosis and 485 age-matched controls were selected between 2012 and 2014. The Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was used for rs35767, rs2288377 and rs5742612 of IGF-1 genotyping. By conditional regression analysis, individuals carrying TT genotype and CT+TT genotype of rs35767 were found to be correlated with an elevated risk of osteoporosis, with adjusted ORs (95% CI) of 1.90 (1.23-2.93) and 1.35 (1.04-1.76), respectively. Our study found that CT+TT genotype of rs35767 was significantly associated with moderate increased risk of osteoporosis in smokers and drinkers, and the ORs (95% CI) were 2.11 (1.06-4.20) and 2.36 (1.29-4.32), respectively. We found that those carrying CT+TT genotype of rs35767 had a significant lower BMD levels at L1-L4 vertebrae, femoral neck, total hip and trochanter compared to those with CC genotype. Our study suggests that TT genotype and CT+TT genotype of IGF-I rs35767 were associated with risk of osteoporosis and BMD levels.

Genetic polymorphism in extracellular regulators of Wnt signaling pathway

The Wnt signaling pathway is mediated by a family of secreted glycoproteins through canonical and noncanonical mechanism. The signaling pathways are regulated by various modulators, which are classified into two classes on the basis of their interaction with either Wnt or its receptors. Secreted frizzled-related proteins (sFRPs) are the member of class that binds to Wnt protein and antagonizes Wnt signaling pathway. The other class consists of Dickkopf (DKK) proteins family that binds to Wnt receptor complex. The present review discusses the disease related association of various polymorphisms in Wnt signaling modulators. Furthermore, this review also highlights that some of the sFRPs and DKKs are unable to act as an antagonist for Wnt signaling pathway and thus their function needs to be explored more extensively.