Purinergic P2X7 receptor functional genetic polymorphisms are associated with the susceptibility to osteoporosis in Chinese postmenopausal women

Exonic variants of the P2RX7 gene in familial multiple sclerosis

INTRODUCTION

Several studies have analysed the presence of P2RX7 variants in patients with MS, reporting diverging results.

METHODS

Our study analyses P2RX7 variants detected through whole-exome sequencing (WES).

RESULTS

We analysed P2RX7, P2RX4, and CAMKK2 gene variants detected by whole-exome sequencing in all living members (n = 127) of 21 families including at least 2 individuals with multiple sclerosis. P2RX7 gene polymorphisms previously associated with autoimmune disease. Although no differences were observed between individuals with and without multiple sclerosis, we found greater polymorphism of gain-of-function variants of P2RX7 in families with individuals with multiple sclerosis than in the general population. Copresence of gain-of-function and loss-of-function variants was not observed to reduce the risk of presenting the disease. Three families displayed heterozygous gain-of-function SNPs in patients with multiple sclerosis but not in healthy individuals. We were unable to determine the impact of copresence of P2RX4 and CAMKK2 variants with P2RX7 variants, or the potential effect of the different haplotypes described in the gene. No clinical correlations with other autoimmune diseases were observed in our cohort.

CONCLUSIONS

Our results support the hypothesis that the disease is polygenic and point to a previously unknown mechanism of genetic predisposition to familial forms of multiple sclerosis. P2RX7 gene activity can be modified, which suggests the possibility of preventive pharmacological treatments for families including patients with familial multiple sclerosis.

Associations Between the Purinergic Receptor P2X7 and Leprosy Disease

Leprosy is an infectious disease still highly prevalent in Brazil, having been detected around 27,863 new cases in 2019. Exposure to Mycobacterium leprae may not be sufficient to trigger the disease, which seems to be influenced by host immunogenetics to determine resistance or susceptibility. The purinergic receptor P2X7 plays a crucial role in immunity, inflammation, neurological function, bone homeostasis, and neoplasia and is associated with several infectious and non-infectious diseases. Here, we first compare the P2RX7 expression in RNA-seq experiments from 16 leprosy cases and 16 healthy controls to establish the magnitude of allele-specific expression for single-nucleotide polymorphisms of the gene P2RX7 and to determine the level of gene expression in healthy and diseased skin. In addition, we also evaluated the association of two P2RX7 single-nucleotide polymorphisms (c.1513A>C/rs3751143 and c.1068A>G/rs1718119) with leprosy risk. The expression of P2RX7 was found significantly upregulated at macrophage cells from leprosy patients compared with healthy controls, mainly in macrophages from lepromatous patients. Significant risk for leprosy disease was associated with loss function of rs3751143 homozygous mutant CC [CC vs. AA: p = 0.001; odds ratio (OR) = 1.676, 95% CI = 1.251–2.247] but not with heterozygous AC (AC vs. AA: p = 0.001; OR = 1.429, 95% CI = 1.260–1.621). Contrary, the polymorphic A allele from the gain function of rs1718119 was associated with protection for the development of leprosy, as observed in the dominant model (AA + AG × GG p = 0.0028; OR = 0.03516; CI = 0.1801–0.6864). So, our results suggest that the functional P2X7 purinergic receptor may exert a key role in the Mycobacterium death inside macrophages and inflammatory response, which is necessary to control the disease.

The effect of genetic polymorphisms on treatment duration following premolar extraction

To elucidate genetic factors affecting orthodontic treatment duration, we employed targeted next-generation sequencing on DNA from the saliva of 117 patients undergoing orthodontic treatment after premolar extraction. The clinical characteristics of patients are summarized, and the association of clinical variables with treatment duration was assessed. Patients whose treatment duration deviated from the average were classified into an extreme long group or an extreme short group. We identified nine single nucleotide polymorphisms (SNPs) of six genes that significantly differed in the two groups via targeted sequencing. The frequency of the CC genotypes of WNT3A, SPP1 (rs4754, rs9138), and TNFSF11, TT genotype of SPP1 (rs1126616), and GG genotype of SFRP2 was significantly higher in the extreme long group than in the short group. In the extreme short group, the TC genotype of SPP1, AA genotype of P2RX7, CT genotype of TNFSF11, and AG genotype of TNFRSF11A tended to exhibit higher frequency than in the long group. Taken together, we identified genetic polymorphisms related to treatment duration in Korean orthodontic patients undergoing premolar extraction. Our findings could lead to further studies predicting the prolongation of the orthodontic treatment duration, and will be of great aid to patients as well as orthodontists.

P2X7 receptor in multifaceted cellular signalling and its relevance as a potential therapeutic target in different diseases

P2X7 receptor, a purinergic receptor family member, is abundantly expressed on many cells, including immune, muscle, bone, neuron, and glia. It acts as an ATP-activated cation channel that permits the influx of Ca²⁺, Na⁺ and efflux of K⁺ ions. The P2X7 receptor plays crucial roles in many physiological processes including cytokine and chemokine secretion, NLRP3 inflammasome activation, cellular growth and differentiation, locomotion, wound healing, transcription factors activation, cell death and T-lymphocyte survival. Past studies have demonstrated the up-regulation and direct association of this receptor in many pathophysiological conditions such as cancer, diabetics, arthritis, tuberculosis (TB) and inflammatory diseases. Hence, targeting this receptor is considered a worthwhile approach to lessen the afflictions associated with the disorders mentioned above by understanding the receptor architecture and downstream signalling processes. Here, in the present review, we have dissected the structural and functional aspects of the P2X7 receptor, emphasizing its role in various diseased conditions. This information will provide in-depth knowledge about the receptor and help to develop apt curative methodologies for the betterment of humanity in the coming years.

The BMP signaling pathway enhances the osteoblastic differentiation of bone marrow mesenchymal stem cells in rats with osteoporosis

Background

This study was conducted with the aim of exploring the effect of the BMP signaling pathway on osteoblastic differentiation in rat bone marrow mesenchymal stem cells (rBMSCs) in rats with osteoporosis (OP).

Methods

The bilateral ovaries of female SD rats were resected for the establishment of a rat OP model. The osteoblastic differentiation of isolated rBMSCs was identified through osteogenic induction. Adipogenetic induction and flow cytometry (FCM) were used to detect adipogenic differentiation and the expression of rBMSC surface markers. The rBMSCs were grouped into the blank group, NC group, si-BMP2 group, and oe-BMP2 group. The expression levels of key factors and osteogenesis-related factors were determined by Western blot and quantitative real-time polymerase chain reaction (qRT-PCR). The formation of calcified nodules was observed by alizarin red staining. ALP activity was measured by alkaline phosphatase staining.

Results

The rats with OP had greater weight but decreased bone mineral density (BMD) than normal rats (all P < 0.01). The rBMSCs from rats with OP were capable of osteoblastic differentiation and adipogenic differentiation and showed high expression of CD44 (91.3 ± 2.9%) and CD105 (94.8 ± 2.1%). Compared with the blank group, the oe-BMP2 group had elevated BMP-2 and Smad1 levels and an increase in calcified nodules and ALP-positive staining areas (all P < 0.05). Moreover, the expression levels of Runx2, OC, and OPN in the oe-BMP2 group were relatively higher than those in the blank group (all P < 0.05). The findings in the si-BMP2 group were opposite to those in the oe-BMP2 group.

Conclusion

BMP signaling pathways activated by BMP-2 can promote the osteoblastic differentiation of rBMSCs from rats with OP.

Identification of rs11615992 as a novel regulatory SNP for human P2RX7 by allele-specific expression

P2RX7 (purinergic receptor P2X 7) is an important membrane ion channel and involved in multiple physiological processes. One non-synonymous SNP on P2RX7, rs3751143, had been proven to reduce ion channel function and further associated with multiple diseases. However, it was still unclear whether there were other cis-regulatory elements for P2RX7, which might further contribute to related diseases. Allele-specific expression (ASE) is a robust and sensitive approach to identify the potential functional region in human genome. In the current study, we measured ASE on rs3751143 in lung tissues and observed a consistent excess of A allele over C (P = 0.001), which indicated that SNP(s) in linkage disequilibrium (LD) could regulate P2RX7 expression. By analyzing the 1000 genomes project data for Chinese, one SNP locating ~ 5 kb away and downstream of P2RX7, rs11615992, was disclosed to be in strong LD with rs3751143. The dual-luciferase assay confirmed that rs11615992 could alter target gene expression in lung cell line. Through chromosome conformation capture, it was verified that the region surrounding rs11615992 could interact with P2RX7 promoter and effect as an enhancer. By chromatin immunoprecipitation, the related transcription factor POU2F1 (POU class 2 homeobox 1) was recognized to bind the region spanning rs11615992. Our work identified a novel long-distance cis-regulatory SNP for P2RX7, which might contribute to multiple diseases.

Genetic variation of rs7958311 in P2X7R gene is associated with the susceptibility and disease activity of ankylosing spondylitis

OBJECTIVES

To describe association between the genetic variation of inflammation-associated gene, P2X7R, and ankylosing spondylitis (AS) susceptibility.

METHODS

Four single nucleotide polymorphisms (SNPs) of P2 X 7 R gene were genotyped in 673 patients with AS and 687 healthy controls. Allele and genotype frequencies and different genetic models were performed to calculate ORs and 95% CIs, the demographic and clinical characteristics of patients were recorded. The data analyses were also conducted by sex.

RESULTS

Compared with controls, genetic variation in rs7958311 but not the other three SNPs was statistically significant in female patients (χ²=6.907, p=0.032). Specifically, the P2 X 7 R gene rs7958311 polymorphism A allele showed a protective effect in AS susceptibility (OR=0.704, p=0.049, p_FDR=0.061). In addition, female individuals with GA and/or AA genotypes had a lower risk of having AS compared with those with GG genotype (GA vs GG: OR=0.446, p=0.012, p_FDR=0.030; AA vs GG: OR=0.440, p=0.039, p_FDR=0.061; GA/AA vs GG: OR=0.445, p=0.009, p_FDR=0.030). Furthermore, individuals with A allele (ie, GA/AA vs GG) had a higher disease activity, including Bath Ankylosing Spondylitis Disease Activity Index (overall: Z=- 2.630, p=0.014; male: Z=- 2.243, p=0.025), Schober test (overall: Z=- 3.041, p<0.001; male: Z=- 2.243, p=0.025) and chest expansion (overall: Z=- 3.895, p=0.004; male: Z=- 2.403, p=0.016).

CONCLUSION

The allelic variation of rs7958311 SNP in P2X7R gene may have a protective effect on AS susceptibility in females and is associated with disease activity in male patients.

P2X7, a critical regulator and potential target for bone and joint diseases

Abundant evidence indicted that P2X7 receptor show a essential role in human health and some human diseases including hypertension, atherosclerosis, pulmonary inflammation, tuberculosis infection, psychiatric disorders, and cancer. P2X7 receptor also has an important role in some central nervous system diseases such as neurodegenerative disorders. Recently, more research suggested that P2X7 receptor also plays a crucial role in bone and joint diseases. But the effect of P2X7 receptor on skeletal and joint diseases has not been systematically reviewed. In this article, the role of P2X7 receptor in skeletal and joint diseases is elaborated. The activation of P2X7 receptor can ameliorate osteoporosis by inducing a fine balance between osteoclastic resorption and osteoblastic bone formation. The activation of P2X7 receptor can relieve the stress fracture injury by increasing the response to mechanical loading and inducing osteogenesis. But the activation of P2X7 receptor mediates the cell growth and cell proliferation in bone cancer. In addition, the activation of P2X7 receptor can aggravate the process of some joint diseases such as osteoarthritis, rheumatoid arthritis, and acute gouty arthritis. The inhibition of P2X7 receptor can alleviate the pathological process of joint disease to some extent. In conclusion, P2X7 receptor may be a critical regulator and therapeutic target for bone and joint diseases.