Nuclear receptor NR5A2 and bone: gene expression and association with bone mineral density

Association between LRH-1 single nucleotide polymorphisms and unexplained recurrent spontaneous abortion in Chinese Han couples

To explore the genetic relationships between LRH-1 (rs2816948), CYP19 (rs727479 and rs700518), and P450scc (rs4077582) as a potential mechanism behind unexplained recurrent spontaneous abortions in a Chinese Han population. A case-control study was used and featured two groups: Patients with unexplained recurrent miscarriage (n = 82, abortion group) and those who voluntary surrendered of a normal early pregnancy (n = 97, control group). Abortion villi samples were obtained from all patients. Genomic DNA was later extracted and sequenced, after which statistical analyses performed to assess the relationship between single nucleotide polymorphisms and unexplained recurrent spontaneous abortions. There were significant differences in the genotypic and allelic distribution (p < .05) for CYP19 (rs727479) between the abortion and the control groups. There were no significant differences in the genotypic or allelic distributions (p > .05) for either the LRH-1 (rs2816948) or CYP19 (rs700518). There were also significant genotypic differences (p < .05) for P450scc (rs4077582), but no significant differences for its allelic distribution (p > .05). There was a significant correlation between the occurrence of unexplained recurrent spontaneous abortion and CYP19 (rs727479) single nucleotide polymorphisms.

The curious case of Gαs gain-of-function in neoplasia

BACKGROUND

Mutations activating the α subunit of heterotrimeric Gs protein are associated with a number of highly specific pathological molecular phenotypes. One of the best characterized is the McCune Albright syndrome. The disease presents with an increased incidence of neoplasias in specific tissues.

MAIN BODY

A similar repertoire of neoplasms can develop whether mutations occur spontaneously in somatic tissues during fetal development or after birth. Glands are the most "permissive" tissues, recently found to include the entire gastrointestinal tract. High frequency of activating Gαs mutations is associated with precise diagnoses (e.g., IPMN, Pyloric gland adenoma, pituitary toxic adenoma). Typically, most neoplastic lesions, from thyroid to pancreas, remain well differentiated but may be a precursor to aggressive cancer.

CONCLUSIONS

Here we propose the possibility that gain-of-function mutations of Gαs interfere with signals in the microenvironment of permissive tissues and lead to a transversal neoplastic phenotype.

GREB1 genetic variants are associated with bone mineral density in Caucasians

Gaining an understanding of factors contributing to bone quality is key to the development of effective preventative treatments for osteoporosis and reduction in osteoporotic fractures. Oestrogen is a strong regulator of bone remodelling which maintains skeletal structural integrity. The growth regulation by oestrogen in breast cancer 1 (GREB1) gene, with an as yet undefined function, is an early response gene in the oestrogen-regulated pathway. Suggestive evidence of linkage with bone mineral density (BMD) variation has been reported with D2S168, located telomeric of GREB1. The aim of this study was to determine if genetic variation within GREB1 was associated with BMD variation at two sites with high fracture rates-the lumbar spine (LS) and the femoral neck (FN). Informative GREB1 single-nucleotide polymorphisms (SNPs) (n = 12) were selected for genotyping and tested for association in a family-based dataset (n = 508 individuals from 229 families). Significantly associated SNPs were tested further in a postmenopausal dataset from the same geographic region (n = 477 individuals). One intronic SNP, rs5020877, was significantly associated with LS and FN BMD in the family-based dataset (P ≤ 0.005). The association was not observed in the postmenopausal dataset (P > 0.017); however, rs10929757 was significantly associated with FN BMD (P = 0.006). Markers, rs5020877 and rs10929757, were constituent SNPs in one GREB1 linkage disequilibrium block, although not historically correlated (r ² = 0.07). Our findings suggest that GREB1 is a novel gene target for osteoporosis genetics and needs to be investigated further.

Relationship between CATSPERB, NR5A2 gene polymorphisms and Peak Bone Mineral Density in College Students in China

BACKGROUND

Peak bone mineral density (PBMD) is influenced by both genetic and environmental factors, genes explains most of variation. As the novel candidate genes CATSPERB and NR5A2 may have been associated with spinal PBMD in adult. This study was to investigate the relationship among these two genes^ PBMD and the life style factors in young female.

METHODS

The rs1298989 single nucleotide polymorphism (SNP) of the CATSPERB gene and the rs3762397 SNP of the NR5A2 gene were genotyped using SNaPshot® in 359 students from Xinjiang. The prospective study included 203 Han and 156 Uyghur subjects. PBMD was measured using quantitative computed tomography (QCT). Calcium, phosphate and alkaline phosphatase were measured by ELISA method. Physical activity, dietary calcium and life styles were assessed by questionnaire.

RESULTS

Both SNPs showed differences in genotype and allele frequencies (P < 0.05) between the Han and Uyghur subjects. Total calcium intake, energy intake, tea and milk intake were also significantly different between two groups (P < 0.05). Multiple regression analysis showed an association between PBMD and vitamin D intake (P = 0.000), milk (P = 0.000), exercise (P = 0.029), rs1298989 (P = 0.028), energy intake (P = 0.043).

CONCLUSION

This study demonstrated the polymorphisms of the rs1298989 and rs3762397 are associated with PBMD both in Han and Uyghur subjects. PBMD, in Xinjiang, appears to be associated with several known factors that are well described in the literature. While the genotypes of rs1298989 and rs3762397 do not appear have a strong effect on the PBMD.

Role of BMPs in the regulation of sclerostin as revealed by an epigenetic modifier of human bone cells

Sclerostin, encoded by the SOST gene, is specifically expressed by osteocytes. However osteoblasts bear a heavily methylated SOST promoter and therefore do not express SOST. Thus, studying the regulation of human SOST is challenged by the absence of human osteocytic cell lines. Herein, we explore the feasibility of using the induction of SOST expression in osteoblasts by a demethylating agent to study the mechanisms underlying SOST transcription, and specifically, the influence of bone morphogenetic proteins (BMPs). Microarray analysis and quantitative PCR showed that AzadC up-regulated the expression of several BMPs, including BMP-2, BMP-4 and BMP-6, as well as several BMP downstream targets. Recombinant BMP-2 increased the transcriptional activity of the SOST promoter cloned into a reporter vector. Likewise, exposing cells transfected with the vector to AzadC also resulted in increased transcription. On the other hand, inhibition of the canonical BMP signaling blunted the effect of AzadC on SOST. These results show that the AzadC-induced demethylation of the SOST promoter in human osteoblastic cells may be a valuable tool to study the regulation of SOST expression. As a proof of concept, it allowed us to demonstrate that BMPs stimulate SOST expression by a mechanism involving BMPR1A receptors and downstream Smad-dependent pathways.