Association between polymorphisms in period genes and bone density in postmenopausal Korean women

The Association Between Sleep Duration and Sleep-Related Gene Methylation with Osteoporosis in Chinese Postmenopausal Women

This study aims to investigate the association between sleep duration and osteoporosis. In addition, sleep-related gene methylation was also detected in this study and we explored its relationship with osteoporosis. The epidemiological investigation section of this study was designed as a retrospective cross-sectional study. We gathered 148 postmenopausal women from two communities and used questionnaires to collect data of sleep duration and other sleep patterns. Biochemical variables were tested, and bone mineral density was measured by dual-energy X-ray absorptiometry. In addition, sleep-related gene (PER2 and PER3) methylation was tested, and the association with osteoporosis was further studied. Twenty-nine of the 148 participants (aged from 65 to 86 years) who suffered from osteoporosis were tested for osteopenia. A significant difference was observed in the association between sleep duration and osteoporosis; the p-value was 0.013. In addition, in our study, we found that short sleep duration (<7 hours) may increase the risk of osteoporosis compared with longer sleep duration. Moreover, sleep-related genes such as PER2 and PER3 and their CpG island methylation were tested, and there was no significant difference between PER2 and PER3 CpG island methylation and osteoporosis. Short sleep duration may increase the risk of osteoporosis. However, the association between sleep-related gene methylation and osteoporosis was not found.

Effect of adipokine and ghrelin levels on BMD and fracture risk: an updated systematic review and meta-analysis

Context

Circulating adipokines and ghrelin affect bone remodeling by regulating the activation and differentiation of osteoblasts and osteoclasts. Although the correlation between adipokines, ghrelin, and bone mineral density (BMD) has been studied over the decades, its correlations are still controversial. Accordingly, an updated meta-analysis with new findings is needed.

Objective

This study aimed to explore the impact of serum adipokine and ghrelin levels on BMD and osteoporotic fractures through a meta-analysis.

Data sources

Studies published till October 2020 in Medline, Embase, and the Cochrane Library were reviewed.

Study selection

We included studies that measured at least one serum adipokine level and BMD or fracture risk in healthy individuals. We excluded studies with one or more of the following: patients less than 18 years old, patients with comorbidities, who had undergone metabolic treatment, obese patients, patients with high physical activities, and a study that did not distinguish sex or menopausal status.

Data extraction

We extracted the data that include the correlation coefficient between adipokines (leptin, adiponectin, and resistin) and ghrelin and BMD, fracture risk by osteoporotic status from eligible studies.

Data synthesis

A meta-analysis of the pooled correlations between adipokines and BMD was performed, demonstrating that the correlation between leptin and BMD was prominent in postmenopausal women. In most cases, adiponectin levels were inversely correlated with BMD. A meta-analysis was conducted by pooling the mean differences in adipokine levels according to the osteoporotic status. In postmenopausal women, significantly lower leptin (SMD = -0.88) and higher adiponectin (SMD = 0.94) levels were seen in the osteoporosis group than in the control group. By predicting fracture risk, higher leptin levels were associated with lower fracture risk (HR = 0.68), whereas higher adiponectin levels were associated with an increased fracture risk in men (HR = 1.94) and incident vertebral fracture in postmenopausal women (HR = 1.18).

Conclusions

Serum adipokines levels can utilize to predict osteoporotic status and fracture risk of patients.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021224855, identifier CRD42021224855.

ATP-binding cassette g1 regulates osteogenesis via Wnt/β-catenin and AMPK signaling pathways

The dysfunction of bone marrow mesenchymal stem cells (BMSCs) in balancing osteogenesis and adipogenesis plays an important role in the occurrence and development of osteoporosis. It's still unknown that whether ATP-binding cassette g1 (Abcg1), a well-proved regulation gene of adipogenesis, regulates osteogenesis. In our previous study, we identified 30 differentially expressed genes in osteogenesis and found the expression level ofAbcg1 negatively related to osteogenesis among these genes. Abcg1 is a well-proven adipogenesis regulator and cholesterol transporter, but it's role in osteogenesis remained unknown. In this study we found it may control osteogenesis, further elucidating the exact role of Abcg1 in regulating osteoblast differentiation would help propose new strategies to prevent and treat osteoporosis. Therefore, we established Abcg1 up- or down-expressed C3H10T1/2 and C2C12 cell lines and verified that Abcg1 knockdown enhanced expression of osteogenic factors runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP), while Abcg1 overexpression reversed the promoting effect. Furthermore, we confirmed that Abcg1 modulated osteogenesis via the Wnt/β-catenin and AMPK signaling pathways. taken together, these results suggest that Abcg1 may have an important role in regulating osteogenesis via Wnt/β-catenin and AMPK signaling pathways, and expect to be a potential therapeutic target for osteoporosis.

Differential expression of genes associated with hypoxia pathway on bone marrow stem cells in osteoporosis patients with different bone mass index

Background

This study aimed to assess gene expression changes associated with hypoxia pathway on bone marrow stem cells (BMSCs) and explore effects of bone mass index (BMI) on hypoxia pathway of osteoporosis (OP) patients.

Methods

Human BMSCs were isolated from bone marrow. Subjects were divided into healthy control group and OP group which was further divided into BMI <25 OP subgroup and BMI ≥25 OP subgroup.

Results

The genes downregulated in OP patients were involved in hypoxia pathway. Furthermore, those genes were even downregulated in OP patients BMI ≥25 subgroup than OP patients BMI <25 subgroup. The genes were expressed in response to decreased oxygen levels, and their functions are related to photoperiodism, positive regulation of myoblast differentiation, and entrainment of circadian clock by gene ontology (GO) analysis.

Conclusions

The expression of genes associated with hypoxia pathway on BMSCs in OP patients are lower than healthy subjects, and the expression of genes related to carbohydrate metabolism are lower in overweight OP patients than in normal weight OP patients. These results need further research.

Association of osteoporosis with genetic variants of circadian genes in Chinese geriatrics

This study was designed to investigate the association of circadian gene single nucleotide polymorphisms (SNPs) with the risk of osteoporosis. We found that the rs3781638 GG genotype was positively associated with osteoporosis prevalence in females, whereas the rs2292910 AC genotype was negatively associated with osteoporosis prevalence in a geriatric cohort.

INTRODUCTION

Studies have shown that disruption of endogenous circadian rhythms may increase the risk of developing type II diabetes and obesity, which are reportedly associated with osteoporosis (OP). Thus, abnormalities of circadian genes may indirectly induce OP. Here, we investigated the association of OP with 14 SNPs located in seven circadian genes.

METHODS

The research subjects, geriatric residents of Shanghai Minhang, China, diagnosed with OP (N = 171) or osteopenia (N = 226) or without specific diseases (N = 200), were genotyped for 14 genetic variants of circadian genes by competitive allele-specific polymerase chain reaction. The prevalence of polymorphisms among the subject groups and the association between the SNPs and osteoporosis were investigated.

RESULTS

Among the 14 genotyped SNPs, we found an association between the CRY2 gene rs2292910 SNP and osteoporosis (r = -0.082, p = 0.045) in the geriatric cohort. We found a decreased risk between cryptochrome 2 rs2292910 and OP (A/C odds ratio = 0.647, p = 0.044) but an increased risk between MTNR1B rs3781638 and OP (G/G odds ratio = 2.058, p = 0.044).

CONCLUSION

For the first time, we show that Cry 2 rs2292910 and MTNR1B rs3781638 are associated with osteoporosis in a Chinese geriatric cohort. Therefore, targeting the abnormalities of the CRY2 and MTNR1B genes may be a potential strategy to treat and/or to prevent osteoporosis.

Polymorphisms in period genes and bone response to hormone therapy in postmenopausal Korean women

OBJECTIVE

In this study, we aimed to explore the association between polymorphisms in the period (PER) gene and bone response to hormone therapy (HT) in postmenopausal Korean women.

METHODS

The PER1 c.2284C > G, c.2247C > T, PER2 c.3731G > A, PER3 c.2592G > A, c.3083T > C polymorphisms, and PER3 54bp variable number of tandem repeats (VNTR) were analyzed in 509 postmenopausal Korean women who received HT. Bone mineral density (BMD) at the lumbar spine and femoral neck before and after 1 year of HT and serum levels of osteoprotegerin (OPG), soluble receptor activator of the nuclear factor-κB ligand (sRANKL) and bone turnover markers were measured after 6 months of HT.

RESULTS

The PER1 c.2884 C > G polymorphism and PER3 54bp VNTR were associated with annual percent changes in BMD of the femoral neck after 1 year of HT (p < 0.05). Changes in BMD at the femoral neck in the non-CC genotype of the PER1 c.2884C > G polymorphism and in the 4-repeat homozygote of PER3 54bp VNTR were significantly lower than those in CC genotype and non-4-repeat homozygote, respectively. The PER1 c.2884C > G polymorphism was associated with the non-response (>3% BMD loss/year after HT) of HT. The non-CC genotype of the PER1 c.2884C > G polymorphism showed a 1.92-times higher risk of non-response at the lumbar spine and/or femoral neck (p = 0.01) compared with the CC genotype. No significant changes in bone markers after 6 months of HT were noted according to the PER1 c.2884C > G polymorphism.

CONCLUSIONS

The PER1 c.2884C > G polymorphism may be associated with risk of non-response to HT in postmenopausal Korean women.

Plasticity of circadian clocks and consequences for metabolism

The increased prevalence of metabolic disorders and obesity in modern society, together with the widespread use of artificial light at night, have led researchers to investigate whether altered patterns of light exposure contribute to metabolic disorders. This article discusses the experimental evidence that perturbed environmental cycles induce rhythm disorders in the circadian system, thus leading to metabolic disorders. This notion is generally supported by animal studies. Distorted environmental cycles, including continuous exposure to light, affect the neuronal organization of the central circadian pacemaker in the suprachiasmatic nucleus (SCN), its waveform and amplitude of the rhythm in electrical activity. Moreover, repeated exposure to a shifted light cycle or the application of dim light at night are environmental cues that cause a change in SCN function. The effects on the SCN waveform are the result of changes in synchronization among the SCN's neuronal cell population, which lead consistently to metabolic disturbances. Furthermore, we discuss the effects of sleep deprivation and the time of feeding on metabolism, as these factors are associated with exposure to disturbed environmental cycles. Finally, we suggest that these experimental studies reveal a causal relationship between the rhythm disorders and the metabolic disorders observed in epidemiological studies performed in humans.