Promoter polymorphism -119C/G in MYG1 (C12orf10) gene is related to vitiligo susceptibility and Arg4Gln affects mitochondrial entrance of Myg1

MYG1 drives glycolysis and colorectal cancer development through nuclear-mitochondrial collaboration

Metabolic remodeling is a strategy for tumor survival under stress. However, the molecular mechanisms during the metabolic remodeling of colorectal cancer (CRC) remain unclear. Melanocyte proliferating gene 1 (MYG1) is a 3'-5' RNA exonuclease and plays a key role in mitochondrial functions. Here, we uncover that MYG1 expression is upregulated in CRC progression and highly expressed MYG1 promotes glycolysis and CRC progression independent of its exonuclease activity. Mechanistically, nuclear MYG1 recruits HSP90/GSK3β complex to promote PKM2 phosphorylation, increasing its stability. PKM2 transcriptionally activates MYC and promotes MYC-medicated glycolysis. Conversely, c-Myc also transcriptionally upregulates MYG1, driving the progression of CRC. Meanwhile, mitochondrial MYG1 on the one hand inhibits oxidative phosphorylation (OXPHOS), and on the other hand blocks the release of Cyt c from mitochondria and inhibits cell apoptosis. Clinically, patients with KRAS mutation show high expression of MYG1, indicating a high level of glycolysis and a poor prognosis. Targeting MYG1 may disturb metabolic balance of CRC and serve as a potential target for the diagnosis and treatment of CRC.

The Immunogenetics of Vitiligo: An Approach Toward Revealing the Secret of Depigmentation

Vitiligo is a hypomelanotic skin disease and considered to be of autoimmune origin due to breaching of immunological self-tolerance, resulting in inappropriate immune responses against melanocytes. The development of vitiligo includes a strong heritable component. Different strategies ranging from linkage studies to genome-wide association studies are used to explore the genetic factors responsible for the disease. Several vitiligo loci containing the respective genes have been identified which contribute to vitiligo and genetic variants for some of the genes are still unknown. These genes include mainly the proteins that play a role in immune regulation and a few other genes important for apoptosis and regulation of melanocyte functions. Despite the available data on genetic variants and risk alleles which influence the biological processes, only few immunological pathways have been found responsible for all ranges of severity and clinical manifestations of vitiligo. However, studies have concluded that vitiligo is of autoimmune origin and manifests due to complex interactions in immune components and their inappropriate response toward melanocytes. The genes involved in the immune regulation and processing the melanocytes antigen and its presentation can serve as effective immune-therapeutics that can target specific immunological pathways involved in vitiligo. This chapter highlights those immune-regulatory genes involved in vitiligo susceptibility and loci identified to date and their implications in vitiligo pathogenesis.

Role of Cytokines in Vitiligo: Pathogenesis and Possible Targets for Old and New Treatments

Vitiligo is a chronic autoimmune dermatosis of which the pathogenesis remains scarcely known. A wide variety of clinical studies have been proposed to investigate the immune mediators which have shown the most recurrency. However, such trials have produced controversial results. The aim of this review is to summarize the main factors involved in the pathogenesis of vitiligo, the latest findings regarding the cytokines involved and to evaluate the treatments based on the use of biological drugs in order to stop disease progression and achieve repigmentation. According to the results, the most recurrent studies dealt with inhibitors of IFN-gamma and TNF-alpha. It is possible that, given the great deal of cytokines involved in the lesion formation process of vitiligo, other biologics could be developed in the future to be used as adjuvants and/or to entirely replace the treatments that have proven to be unsatisfactory so far.

MYG1 promotes proliferation and inhibits autophagy in lung adenocarcinoma cells via the AMPK/mTOR complex 1 signaling pathway

Melanocyte proliferating gene 1 (MYG1) is an exonuclease that participates in RNA processing and is required for normal mitochondrial function. However, its role in tumorigenesis remains unknown. The present study aimed to investigate the role of MYG1 and its underlying mechanisms in human lung adenocarcinoma (LUAD). The expression levels of MYG1 in tumor tissues of patients with LUAD were obtained from public cancer databases and analyzed using the UALCAN online software. The association between MYG1 expression levels and the prognosis of patients with LUAD was analyzed using the Kaplan-Meier plotter. In addition, the role of MYG1 in the LUAD A549 and H1993 cell lines was determined by knocking down MYG1 expression with a specific small interfering RNA or by overexpressing it with a MYG1-containing plasmid. The results demonstrated that MYG1 expression levels were upregulated in LUAD tissues compared with those in normal lung tissues from healthy subjects, and high MYG1 expression levels were associated with an unfavorable prognosis. MYG1 promoted the proliferation, migration and invasion of A549 and H1993 cells. In addition, MYG1 inhibited autophagy via the AMP-activated protein kinase/mTOR complex 1 signaling pathway. Collectively, the present results suggested that MYG1 may serve an oncogenic role in LUAD and may be a potential therapeutic target for LUAD.

Differential gene expression and limited epigenetic dysregulation at the materno-fetal interface in preeclampsia

Despite the many advances made in the diagnosis and management of preeclampsia, this syndrome remains a leading cause of maternal mortality and life-long morbidity, as well as adverse fetal outcomes. Successful prediction and therapeutic intervention require an improved understanding of the molecular mechanisms, which underlie preeclampsia pathophysiology. We have used an integrated approach to discover placental genetic and epigenetic markers of preeclampsia and validated our findings in an independent cohort of women. We observed the microRNA, MIR138, to be upregulated in singleton preeclamptic placentas; however, this appears to be a female infant sex-specific effect. We did not identify any significant differentially methylated positions (DMPs) in singleton pregnancies, indicating that DNA methylation changes in mild forms of the disease are likely limited. However, we identified infant sex-specific preeclampsia-associated differentially methylated regions among singletons. Disease-associated DMPs were more obvious in a limited sampling of twin pregnancies. Interestingly, 2 out of the 10 most significant changes in methylation over larger regions overlap between singletons and twins and correspond to NAPRT1 and ZNF417.

Altered Expression Profile of IgLON Family of Neural Cell Adhesion Molecules in the Dorsolateral Prefrontal Cortex of Schizophrenic Patients

Neural adhesion proteins are crucial in the development and maintenance of functional neural connectivity. Growing evidence suggests that the IgLON family of neural adhesion molecules LSAMP, NTM, NEGR1, and OPCML are important candidates in forming the susceptibility to schizophrenia (SCZ). IgLON proteins have been shown to be involved in neurite outgrowth, synaptic plasticity and neuronal connectivity, all of which have been shown to be altered in the brains of patients with the diagnosis of schizophrenia. Here we optimized custom 5'-isoform-specific TaqMan gene-expression analysis for the transcripts of human IgLON genes to study the expression of IgLONs in the dorsolateral prefrontal cortex (DLPFC) of schizophrenic patients (n = 36) and control subjects (n = 36). Uniform 5'-region and a single promoter was confirmed for the human NEGR1 gene by in silico analysis. IgLON5, a recently described family member, was also included in the study. We detected significantly elevated levels of the NEGR1 transcript (1.33-fold increase) and the NTM 1b isoform transcript (1.47-fold increase) in the DLPFC of schizophrenia patients compared to healthy controls. Consequent protein analysis performed in male subjects confirmed the increase in NEGR1 protein content both in patients with the paranoid subtype and in patients with other subtypes. In-group analysis of patients revealed that lower expression of certain IgLON transcripts, mostly LSAMP 1a and 1b, could be related with concurrent depressive endophenotype in schizophrenic patients. Additionally, our study cohort provides further evidence that cannabis use may be a relevant risk factor associated with suicidal behaviors in psychotic patients. In conclusion, we provide clinical evidence of increased expression levels of particular IgLON family members in the DLPFC of schizophrenic patients. We propose that alterations in the expression profile of IgLON neural adhesion molecules are associated with brain circuit disorganization in neuropsychiatric disorders, such as schizophrenia. In the light of previously published data, we suggest that increased level of NEGR1 in the frontal cortex may serve as molecular marker for a wider spectrum of psychiatric conditions.

Modern vitiligo genetics sheds new light on an ancient disease

Vitiligo is a complex disorder in which autoimmune destruction of melanocytes results in white patches of skin and overlying hair. Over the past several years, extensive genetic studies have outlined a biological framework of vitiligo pathobiology that underscores its relationship to other autoimmune diseases. This biological framework offers insight into both vitiligo pathogenesis and perhaps avenues towards more effective approaches to treatment and even disease prevention.

Correlation of increased MYG1 expression and its promoter polymorphism with disease progression and higher susceptibility in vitiligo patients

BACKGROUND

MYG1 (Melanocyte proliferating gene 1 or C12orf10) -119C/G promoter and Arg4Gln structural polymorphisms have a functional impact on its regulation. The promoter polymorphism was shown to be associated with vitiligo in Caucasian population.

OBJECTIVE

The present study explores MYG1 polymorphisms and correlates them with MYG1 mRNA expression, disease onset and progression in vitiligo patients.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for genotyping of MYG1 -119C/G promoter (rs1465073) and 11-12AA/GC structural polymorphisms (rs1534284-rs1534283; Arg4Gln) in 846 vitiligo patients and 726 age-matched unaffected controls. MYG1 mRNA levels were assessed in whole blood of 166 patients and 175 controls by Real-time PCR.

RESULTS

The MYG1 -119C/G promoter polymorphism was found to be in significant association with vitiligo being 'G' allele prevalent in patients. However, 11-12AA/GC structural polymorphism was prevalently monogenic in patients and controls with only MYG1 GC (4Arg) allele being present. Significant increase in MYG1 mRNA expression was observed in vitiligo patients compared to controls. The MYG1 mRNA expression was increased in patients with active and generalized vitiligo as compared to stable and localized vitiligo. MYG1 mRNA expression was increased in patients with susceptible -119 GG genotype compared to controls. Also, patients with susceptible -119 GG genotype had early age of onset of vitiligo. Moreover, patients with age groups 1-20 years and 21-40 years showed increased expression of MYG1 mRNA compared to those of controls. Female patients showed significant increase in MYG1 mRNA and early age of onset of vitiligo compared to male patients.

CONCLUSION

The present study suggests that MYG1 -119C/G promoter polymorphism may be a genetic risk factor for susceptibility and progression of vitiligo. The up-regulation of MYG1 transcript in patients with susceptible -119GG genotype advocates the crucial role of MYG1 in autoimmune pathogenesis of vitiligo.

The pathogenesis of vitiligo

BACKGROUND

Vitiligo is a commonly encountered pigmentary disorder. Numerous studies and investigations from all over the world have attempted to determine the mechanisms behind this disease; however, the pathogenesis of vitiligo remains elusive.

OBJECTIVE

n this comprehensive review article, we present the findings behind the five overarching theories of what causes this disfiguring and psychologically debilitating disease.

METHOD

We begin our discussion with the role of genetic predisposition and move onward to the neural theory first proposed in the 1950s. Next we discuss the autoimmune hypothesis, followed by the reactive oxygen species model, and conclude by describing the findings of the more recent melanocytorrhagy hypothesis.

CONCLUSION

Although the exact pathogenesis of vitiligo is uncertain, each of these theories likely plays a role. Understanding each theory would pave the way for therapeutic advances for this disease.

Association of ACE gene I/D polymorphism with vitiligo: a meta-analysis

Associations of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) functional single-nucleotide polymorphisms (SNPs) with vitiligo have been reported, but the results were inconsistent. To investigate the association of SNPs in the intron 16 of ACE gene with vitiligo susceptibility by the meta-analysis, case-control studies were conducted by searching from PubMed, HighWire and China National Knowledge Infrastructure as of May 2011. A total of 6 studies with 828 patients and 1,215 controls was finally identified. All control samples were in Hardy-Weinberg equilibrium. According to the clinical typing, the data were divided into pooled subgroup and generalized subgroup. Our meta-analysis showed that a significantly increased vitiligo risk was associated with the D/D genotype compared with the I/I + I/D genotype (Odds ratio (OR) 1.79, 95% confidence interval (95% CI) 1.35-2.38, P < 0.0001) and the D allele compared with the I allele (OR 1.72, 95% CI 1.45-2.04, P < 0.00001) in pooled subgroup. In summary, this meta-analysis demonstrated that ACE D/D homozygote and D allele were significantly associated with an increased risk of vitiligo in pooled population. The results indicated that the people with ACE D/D homozygote and D allele may suffer from vitiligo, but of a generalized type. ACE polymorphism might be used as biomarkers for vitiligo risk prediction for pooled vitiligo.

Update on the genetics characterization of vitiligo

Vitiligo is an autoimmune skin disorder in which autoimmune-mediated destruction of melanocytes caused depigmentation of skin patches. The complex genetics of vitiligo involves multiple susceptibility loci, genetic heterogeneity and incomplete penetrance with gene-gene and gene-environment interactions. In order to clarify the genetic factors, two different principal approaches have applied for the identification of genomic regions or candidate genes that mediate susceptibility to vitiligo. First approach is the genome-wide linkage analyses, which is conducted by scanning of entire human genome for genomic regions that are linked to the development of vitiligo. The other approach is functional candidate gene association (FCGA) analyses that detect specific candidate genes, which are expected to involve in disease on the basis of their priori biological functions. Genomic-wide scans have provided a strong support for vitiligo susceptibility genes on chromosomes 4q13-q21, 1p31, 7q22, 8p12 and 17p13, while loci of interest at 6p, 6q, 14q, 9q, 13q, 19p and 22q required further follow-up. Whereas, FCGA studies have identified some candidate genes which are associated with vitiligo, such as HLA, AIRE, VIT1, CAT, FOXD3, ESR1, COMT, PTPN22, NALP1, PDGFRA, MYG1, MITF, CD117, XBP1, FAS, COX2, EDN1 and ACE, but few of them reports now appear to be false-positive. This review will provides an update on genetics of vitiligo based on the identification of novel candidate genes that represent, in my opinion as optimal utility for future therapeutic targets in the pathogenesis of vitiligo.

Recent progress in the genetics of generalized vitiligo

Vitiligo is an acquired disease characterized principally by patchy depigmentation of skin and overlying hair. Generalized vitiligo (GV), the predominant form of the disorder, results from autoimmune loss of melanocytes from affected regions. GV is a "complex trait", inherited in a non-Mendelian polygenic, multifactorial manner. GV is epidemiologically associated with other autoimmune diseases, both in GV patients and in their close relatives, suggesting that shared genes underlie susceptibility to this group of diseases. Early candidate gene association studies yielded a few successes, such as PTPN22, but most such reports now appear to be false-positives. Subsequent genomewide linkage studies identified NLRP1 and XBP1, apparent true GV susceptibility genes involved in immune regulation, and recent genome-wide association studies (GWAS) of GV in Caucasian and Chinese populations have yielded a large number of additional validated GV susceptibility genes. Together, these genes highlight biological systems and pathways that reach from the immune cells to the melanocyte, and provide insights into both disease pathogenesis and potential new targets for both treatment and even prevention of GV and other autoimmune diseases in genetically susceptible individuals.

Comprehensive association analysis of candidate genes for generalized vitiligo supports XBP1, FOXP3, and TSLP

We previously carried out a genome-wide association study of generalized vitiligo (GV) in non-Hispanic whites, identifying 13 confirmed susceptibility loci. In this study, we re-analyzed the genome-wide data set (comprising 1,392 cases and 2,629 controls) to specifically test association of all 33 GV candidate genes that have previously been suggested for GV, followed by meta-analysis incorporating both current and previously published data. We detected association of three of the candidate genes tested: TSLP (rs764916, P=3.0E-04, odds ratio (OR)=1.60; meta-P for rs3806933=3.1E-03), XBP1 (rs6005863, P=3.6E-04, OR=1.17; meta-P for rs2269577=9.5E-09), and FOXP3 (rs11798415, P=5.8E-04, OR=1.19). Association of GV with CTLA4 (rs12992492, P=5.9E-05, OR=1.20; meta-P for rs231775=1.0E-04) seems to be secondary to epidemiological association with other concomitant autoimmune diseases. Within the major histocompatibility complex (MHC), at 6p21.33, association with TAP1-PSMB8 (rs3819721, P=5.2E-06) seems to derive from linkage disequilibrium with major primary signals in the MHC class I and class II regions.

Shared genetic relationships underlying generalized vitiligo and autoimmune thyroid disease

BACKGROUND

Generalized vitiligo is an autoimmune disease of skin pigmentation that is associated with increased prevalence of other autoimmune diseases, particularly autoimmune thyroid disease (AITD; principally Hashimoto's disease and Graves' disease), both in vitiligo patients and their close relatives, suggesting a heritable predisposition involving, in part, shared susceptibility genes.

SUMMARY

This review summarizes current knowledge of vitiligo epidemiology and genetics, highlighting recent findings from genome-wide approaches to disease gene identification, emphasizing susceptibility loci shared with other autoimmune diseases, particularly AITD, as well as some important differences.

CONCLUSIONS

Inherited susceptibility to generalized vitiligo involves a number of specific genes, many of which are shared with other autoimmune diseases that are epidemiologically associated with vitiligo, including AITD, confirming a longstanding hypothesis about the genetic basis of these disorders. These genes provide potential therapeutic targets for novel approaches to treatment as well as for approaches to presymptomatic diagnosis and disease prevention in individuals with inherited susceptibility to this group of autoimmune diseases.