Impact of single-nucleotide polymorphisms at the TP53-binding and responsive promoter region of BCL2 gene in modulating the phenotypic variability of LGMD2C patients

Association of XRCC3, XRCC4, BAX, and BCL-2 Polymorphisms with the Risk of Breast Cancer

Background

Breast cancer is the most common malignancy in women. Genetic risk factors associated with breast cancer incidence have been identified.

Aims

This study is aimed at determining the association of XRCC3 Thr241Met (rs861539), XRCC4 G(-1394) T (rs6869366) DNA repair and BAX G(-248) A (rs4645878), and BCL2 C(-938) A (rs2279115) apoptotic gene polymorphisms with breast cancer.

Materials and Methods

Genetic analysis was performed using peripheral blood samples. Gene polymorphisms were detected by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. 175 patients and 158 healthy controls were enrolled in the study.

Results

Breast cancer risk was 5.43 times more in individuals with AA genotype of Bax G(-248) A (rs4645878) (P = 0.002). The risk of metastasis was 11 times with this genotype. It was associated with 6 times more risk of having a tumor larger than 2 cm. The risk of breast cancer was 2.77 times more in individuals carrying the Met/Met genotype of XRCC3 Thr241Met (rs861539) (P = 0.009). The risk of having advanced clinical stage (stage III+IV) with the Met/Met genotype was 4 times more increased. No relationship with breast cancer was found with XRCC4 G(-1394) T (rs6869366) and BCL2 C(-938) A (rs2279115) gene polymorphisms.

Conclusion

Multicenter trials using subjects with genetic variations are needed to establish the relationship between breast cancer and single gene polymorphism.

Importance of TP53 codon 72 and intron 3 duplication 16 bp polymorphisms and their haplotypes in susceptibility to sarcopenia in Iranian older adults

Background

Sarcopenia is described as age-related progressive skeletal muscle failure that results in marked reduction in the patient’s independence and life quality. In this study, we explored the association of TP53 exon 4 Arg72pro (rs1042522) and Intron 3 16-bp Del/Ins (rs17878362) polymorphisms and their haplotypes with sarcopenia, anthropometric, body composition and biochemical parameters.

Methods

A total of 254 older individuals (65 sarcopenic and 189 healthy) were recruited in this research and genotyped by PCR–RFLP. Linear regression was applied to find the correlation between TP53 polymorphism, and biochemical and anthropometric parameters. The correlation between TP53 polymorphism and haplotypes and the risk of sarcopenia was investigated by logistic regression.

Results

Arg/Pro genotype carriers was at a lower (ORadj = 0.175, 95% CI = 0.068 – 0.447; P < 0.001) risk of sarcopenia compared to the Arg/Arg group. In haplotypes analysis, Arg-Ins (ORadj: 0.484, 95% CI = 0.231 – 1.011, P = 0.043) and Pro-Ins (ORadj: 0.473, 95% CI = 0.210 – 1.068, P = 0.022) haplotypes showed decreased risk of developing sarcopenia. Moreover, in the case of codon 72 polymorphism, skeletal muscle mass, appendicular lean mass (ALM), skeletal muscle mass index (SMI), hand grip strength and Triglycerides, for Intron 3 16-bp Del/Ins polymorphism, albumin, calcium, cholesterol, and LDL were different, and for the haplotypes, skeletal muscle mass, SMI, ALM, HDL and triglycerides were significantly different between groups.

Conclusions

We suggested that the Arg/Pro genotype of the codon 72 polymorphism in exon 4 of TP53, and Arginine-Insertion and Proline-Insertion haplotypes might decrease the risk of sarcopenia in Iranian older adults.

The ties that bind: functional clusters in limb-girdle muscular dystrophy

The limb-girdle muscular dystrophies (LGMDs) are a genetically pleiomorphic class of inherited muscle diseases that are known to share phenotypic features. Selected LGMD genetic subtypes have been studied extensively in affected humans and various animal models. In some cases, these investigations have led to human clinical trials of potential disease-modifying therapies, including gene replacement strategies for individual subtypes using adeno-associated virus (AAV) vectors. The cellular localizations of most proteins associated with LGMD have been determined. However, the functions of these proteins are less uniformly characterized, thus limiting our knowledge of potential common disease mechanisms across subtype boundaries. Correspondingly, broad therapeutic strategies that could each target multiple LGMD subtypes remain less developed. We believe that three major "functional clusters" of subcellular activities relevant to LGMD merit further investigation. The best known of these is the glycosylation modifications associated with the dystroglycan complex. The other two, mechanical signaling and mitochondrial dysfunction, have been studied less systematically but are just as promising with respect to the identification of significant mechanistic subgroups of LGMD. A deeper understanding of these disease pathways could yield a new generation of precision therapies that would each be expected to treat a broader range of LGMD patients than a single subtype, thus expanding the scope of the molecular medicines that may be developed for this complex array of muscular dystrophies.

Intake of Red and Processed Meat, Use of Non-Steroid Anti-Inflammatory Drugs, Genetic Variants and Risk of Colorectal Cancer: A Prospective Study of the Danish "Diet, Cancer and Health" Cohort

Red and processed meat have been associated with increased risk of colorectal cancer (CRC), whereas long-term use of non-steroid anti-inflammatory drugs (NSAIDs) may reduce the risk. The aim was to investigate potential interactions between meat intake, NSAID use, and gene variants in fatty acid metabolism and NSAID pathways in relation to the risk of CRC. A nested case-cohort study of 1038 CRC cases and 1857 randomly selected participants from the Danish prospective “Diet, Cancer and Health” study encompassing 57,053 persons was performed using the Cox proportional hazard model. Gene variants in SLC25A20, PRKAB1, LPCAT1, PLA2G4A, ALOX5, PTGER3, TP53, CCAT2, TCF7L2, and BCL2 were investigated. CCAT2 rs6983267 was associated with the risk of CRC per se (p < 0.01). Statistically significant interactions were found between intake of red and processed meat and CCAT2 rs6983267, TP53 rs1042522, LPCAT1 rs7737692, SLC25A20 rs7623023 (p_interaction = 0.04, 0.04, 0.02, 0.03, respectively), and the use of NSAID and alcohol intake and TP53 rs1042522 (p_interaction = 0.04, 0.04, respectively) in relation to the risk of CRC. No other consistent associations or interactions were found. This study replicated an association of CCAT2 rs6983267 with CRC and an interaction between TP53 rs1042522 and NSAID in relation to CRC. Interactions between genetic variants in fatty acid metabolism and NSAID pathways and the intake of red and processed meat were found. Our results suggest that meat intake and NSAID use affect the same carcinogenic mechanisms. All new findings should be sought replicated in independent prospective studies. Future studies on the cancer-protective effects of aspirin/NSAID should include gene and meat assessments.

Association study of apoptosis gene polymorphisms in mitochondrial diabetes: A potential role in the pathogenicity of MD

Mitochondrial diabetes (MD) is a heterogeneous disorder characterized by a chronic hyperglycemia and is maternally transmitted. Syndromic MD is a subgroup of MD including diabetic microangiopathy and macroangiopathy, in addition to extrapancreatic disorder. MD is caused by genetic mutations and deletions affecting mitochondrial DNA. This mitochondrial damage initiates apoptosis. In this study, we hypothesized that functional polymorphisms in genes involved in apoptotic pathway could be associated with the development of apoptosis in MD disease and increased its risk. Detection of apoptosis was confirmed on muscle biopsies taken from MD patients using the TUNEL method and the Cytochrome c protein expression level. We genotyped then 11 published SNPs from intrinsic and extrinsic apoptotic pathway and assessed the signification of these polymorphisms in 43 MD patients and 100 healthy controls. We found 10 selected polymorphisms (p53 (rs1042522 and rs17878362), BCL2 (rs2279115), BAX (rs1805419), BAK1 (rs210132 and rs2227925), CASP3 (rs1405937), CASP7 (rs2227310), CASP8 (rs1045485) and CASP10 (rs13006529)) with a potential apoptosis effect in MD patients compared to control population. Specifically, SNPs involved in the intrinsic pathway (p53, BCL2, BAK1 and CASP3) presented the highest risk of apoptosis. Our result proved that apoptosis initiated by mtDNA mutations, can be emphasized by a functional apoptotic polymorphisms associated with high expression of cytochrome c protein and more myofibers with apoptosis in syndromic MD subgroup compared with non-syndromic MD subgroup.

Three single nucleotide polymorphisms associated with type 2 diabetes mellitus in a Chinese population

An Indian study recently observed three new loci: rs9552911 in the SGCG, rs1593304 near PLXNA4 and rs4858889 in SCAP associated with type 2 diabetes mellitus (T2DM) in a south Asian population. The present study aimed to validate these findings in a Chinese population. We genotyped the above three single-nucleotide polymorphisms (SNPs), rs9552911, rs1593304, and rs4858889, in a group of 1,972 Chinese individuals, comprising of 966 type 2 diabetic patients and 976 controls. Anthropometric variables and biochemical traits were measured in all the participants. The association analyses of genotype-disease and genotype-traits were estimated. The genotype frequency of rs9552911 differed statistically between the cases and controls (P=0.017). The difference was also evident between the cases and controls in non-obese participants (P=0.033). In addition, the SNP rs9552911 was associated with weight (P=0.033), total cholesterol (P=0.006) and low-density lipoprotein-cholesterol (P=0.007). The SNP rs1593304 was associated with β-cell function estimated by the homeostatic model assessment of β-cell function (P=0.041). However, there was no significant association between rs4858889 and T2DM. In conclusion, the results show that the SNP rs9552911 was associated with T2DM, possibly by affecting body mass index and lipid metabolism. The SNP rs1593304 may impair β-cell function.

α-Linolenic Acid Reduces TNF-Induced Apoptosis in C2C12 Myoblasts by Regulating Expression of Apoptotic Proteins

Impaired regeneration and consequent muscle wasting is a major feature of muscle degenerative diseases. Nutritional interventions such as adjuvant strategy for preventing these conditions are recently gaining increasing attention. Ingestion of n3-polyunsaturated fatty acids has been suggested as having a positive impact on muscle diseases. We recently demonstrated that a diet enriched with plant derived n3-fatty acid, α-linolenic acid (ALA), exerts potent beneficial effects in preserving skeletal muscle regeneration in models of muscle dystrophy. To better elucidate the underlying mechanism we here investigate on the expression level of the anti- and pro-apoptotic proteins, as well as caspase-3 activity, in C2C12 myoblasts challenged with pathological levels of tumor necrosis factor-α (TNF). The results demonstrated that ALA protective effect on C2C12 myoblasts was associated with a decrease in caspase-3 activity and an increase of the Bcl-2/Bax ratio. Indeed, the effect of ALA was directed to rescuing Bcl-2 expression and to revert Bax translocation to mitochondria both affected in an opposite way by TNF, a major pro-inflammatory cytokine expressed in damaged skeletal muscle. Therefore, ALA counteracts inflammatory signals in the muscle microenvironment and may represent a valuable strategy for ameliorating skeletal muscle pathologies.

Halofuginone promotes satellite cell activation and survival in muscular dystrophies

Halofuginone is a leading agent in preventing fibrosis and inflammation in various muscular dystrophies. We hypothesized that in addition to these actions, halofuginone directly promotes the cell-cycle events of satellite cells in the mdx and dysf(-/-) mouse models of early-onset Duchenne muscular dystrophy and late-onset dysferlinopathy, respectively. In both models, addition of halofuginone to freshly prepared single gastrocnemius myofibers derived from 6-week-old mice increased BrdU incorporation at as early as 18h of incubation, as well as phospho-histone H3 (PHH3) and MyoD protein expression in the attached satellite cells, while having no apparent effect on myofibers derived from wild-type mice. BrdU incorporation was abolished by an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated protein kinase, suggesting involvement of this pathway in mediating halofuginone's effects on cell-cycle events. In cultures of myofibers and myoblasts isolated from dysf(-/-) mice, halofuginone reduced Bax and induced Bcl2 expression levels and induced Akt phosphorylation in a time-dependent manner. Addition of an inhibitor of the phosphinositide-3-kinase/Akt pathway reversed the halofuginone-induced cell survival, suggesting this pathway's involvement in mediating halofuginone's effects on survival. Thus, in addition to its known role in inhibiting fibrosis and inflammation, halofuginone plays a direct role in satellite cell activity and survival in muscular dystrophies, regardless of the mutation. These actions are of the utmost importance for improving muscle pathology and function in muscular dystrophies.

Halofuginone improves muscle-cell survival in muscular dystrophies

Halofuginone has been shown to prevent fibrosis via the transforming growth factor-β/Smad3 pathway in muscular dystrophies. We hypothesized that halofuginone would reduce apoptosis--the presumed cause of satellite-cell depletion during muscle degradation-in the mdx mouse model of Duchenne muscular dystrophy. Six-week-old mdx mouse diaphragm exhibited fourfold higher numbers of apoptotic nuclei compared with wild-type mice as determined by a TUNEL assay. Apoptotic nuclei were found in macrophages and in Pax7-expressing cells; some were located in centrally-nucleated regenerating myofibers. Halofuginone treatment of mdx mice reduced the apoptotic nuclei number in the diaphragm, together with reduction in Bax and induction in Bcl2 levels in myofibers isolated from these mice. A similar effect was observed when halofuginone was added to cultured myofibers. No apparent effect of halofuginone was observed in wild-type mice. Inhibition of apoptosis or staurosporine-induced apoptosis by halofuginone in mdx primary myoblasts and C2 myogenic cell line, respectively, was reflected by less pyknotic/apoptotic cells and reduced Bax expression. This reduction was reversed by a phosphinositide-3-kinase and mitogen-activated protein kinase/extracellular signal-regulated protein kinase inhibitors, suggesting involvement of these pathways in mediating halofuginone's effects on apoptosis. Halofuginone increased apoptosis in α smooth muscle actin- and prolyl 4-hydroxylase β-expressing cells in mdx diaphragm and in myofibroblasts, the major source of extracellular matrix. The data suggest an additional mechanism by which halofuginone improves muscle pathology and function in muscular dystrophies.

ZASP interacts with the mechanosensing protein Ankrd2 and p53 in the signalling network of striated muscle

ZASP is a cytoskeletal PDZ-LIM protein predominantly expressed in striated muscle. It forms multiprotein complexes and plays a pivotal role in the structural integrity of sarcomeres. Mutations in the ZASP protein are associated with myofibrillar myopathy, left ventricular non-compaction and dilated cardiomyopathy. The ablation of its murine homologue Cypher results in neonatal lethality. ZASP has several alternatively spliced isoforms, in this paper we clarify the nomenclature of its human isoforms as well as their dynamics and expression pattern in striated muscle. Interaction is demonstrated between ZASP and two new binding partners both of which have roles in signalling, regulation of gene expression and muscle differentiation; the mechanosensing protein Ankrd2 and the tumour suppressor protein p53. These proteins and ZASP form a triple complex that appears to facilitate poly-SUMOylation of p53. We also show the importance of two of its functional domains, the ZM-motif and the PDZ domain. The PDZ domain can bind directly to both Ankrd2 and p53 indicating that there is no competition between it and p53 for the same binding site on Ankrd2. However there is competition for this binding site between p53 and a region of the ZASP protein lacking the PDZ domain, but containing the ZM-motif. ZASP is negative regulator of p53 in transactivation experiments with the p53-responsive promoters, MDM2 and BAX. Mutations in the ZASP ZM-motif induce modification in protein turnover. In fact, two mutants, A165V and A171T, were not able to bind Ankrd2 and bound only poorly to alpha-actinin2. This is important since the A165V mutation is responsible for zaspopathy, a well characterized autosomal dominant distal myopathy. Although the mechanism by which this mutant causes disease is still unknown, this is the first indication of how a ZASP disease associated mutant protein differs from that of the wild type ZASP protein.

Limb-girdle muscular dystrophies: where next after six decades from the first proposal (Review)

Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of disorders, which has led to certain investigators disputing its rationality. The mutual feature of LGMD is limb-girdle affection. Magnetic resonance imaging (MRI), perioral skin biopsies, blood-based assays, reverse-protein arrays, proteomic analyses, gene chips and next generation sequencing are the leading diagnostic techniques for LGMD and gene, cell and pharmaceutical treatments are the mainstay therapies for these genetic disorders. Recently, more highlights have been shed on disease biomarkers to follow up disease progression and to monitor therapeutic responsiveness in future trials. In this study, we review LGMD from a variety of aspects, paying specific attention to newly evolving research, with the purpose of bringing this information into the clinical setting to aid the development of novel therapeutic strategies for this hereditary disease. In conclusion, substantial progress in our ability to diagnose and treat LGMD has been made in recent decades, however enhancing our understanding of the detailed pathophysiology of LGMD may enhance our ability to improve disease outcome in subsequent years.

Influence of BCL2 gene in major depression susceptibility and antidepressant treatment outcome

BACKGROUND

Our recent work indicated that low-expression of the anti-apoptotic protein B-cell/lymphoma 2 (Bcl-2) mRNA was observed among untreated major depressive disorder (MDD) patients, and the subsequent altered level of Bcl-2 was found to be close to the antidepressant treatment outcome. The primary aim of this present study was to examine whether a particular gene, encoding Bcl-2 (BCL2) confers risk to MDD, and likewise to investigate whether this gene acts as an indicator of antidepressant treatment outcome.

METHODS

We enrolled 178 treatment-resistant depression (TRD) and 612 non-treatment-resistant depression (NTRD) patients as well as 725 healthy controls. In total, three selected tagging SNPs (tagSNPs) of BCL2 (rs2279115, rs1801018 and rs1564483) were genotyped to test for possible association. Using TaqMan relative quantitative real-time polymerase chain reaction (PCR), we analyzed leukocytic expression of BCL2 mRNA in 47 healthy subjects.

RESULTS

Of the three SNPs, we observed no significant differences in genotype and allele frequencies between the MDD and control groups as well as between the TRD and NTRD groups. However, we found a significant association between the rs2279115C allele and TRD in males (corrected P=0.048) but not in females. Further real-time quantitative PCR analysis in healthy subjects revealed that the rs2279115 polymorphism significantly influenced BCL2 mRNA expression (P=0.03).

LIMITATIONS

This is a preliminary investigation with relatively small sample size and cross-sectional design.

CONCLUSIONS

These initial findings strengthen the hypothesis that BCL2 may play an important role in mediating the outcome of antidepressant treatment, a result that may further be confirmed by future genetic studies from large-scale populations that can overcome the limited sample size of this preliminary finding.