Functional variants in SUMO4, TAB2, and NFκB and the risk of type 1 diabetes

Associations between TAB2 gene polymorphisms and dilated cardiomyopathy in a Chinese population

Aim: The present study aimed to investigate the role of TAB2 gene polymorphisms in dilated cardiomyopathy (DCM) susceptibility and prognosis in a Chinese population. Materials & methods: A total of 343 DCM patients and 451 controls were enrolled and had their blood genotyped. Survival analysis was evaluated with Kaplan-Meier curves and Cox regression analysis. Results: G carriers (AG/GG) and AG genotype of rs237028 had a higher DCM susceptibility as well as a worse DCM prognosis. Additionally, C carriers (CT/CC) of rs652921 and G carriers (TG/GG) of rs521845 had a higher DCM risk and CC homozygote of rs652921 had a worse DCM prognosis. These associations were still significant after adjustment for the Bonferroni correction. Conclusion: TAB2 gene polymorphisms were associated with DCM susceptibility and prognosis in the Chinese population.

Ginkgolic Acid Rescues Lens Epithelial Cells from Injury Caused by Redox Regulated-Aberrant Sumoylation Signaling by Reviving Prdx6 and Sp1 Expression and Activities

Sumoylation is a downstream effector of aging/oxidative stress; excess oxidative stress leads to dysregulation of a specificity protein1 (Sp1) and its target genes, such as Peroxiredoxin 6 (Prdx6), resulting in cellular damage. To cope with oxidative stress, cells rely on a signaling pathway involving redox-sensitive genes. Herein, we examined the therapeutic efficacy of the small molecule Ginkgolic acid (GA), a Sumoylation antagonist, to disrupt aberrant Sumoylation signaling in human and mouse lens epithelial cells (LECs) facing oxidative stress or aberrantly expressing Sumo1 (small ubiquitin-like modifier). We found that GA globally reduced aberrant Sumoylation of proteins. In contrast, Betulinic acid (BA), a Sumoylation agonist, augmented the process. GA increased Sp1 and Prdx6 expression by disrupting the Sumoylation signaling, while BA repressed the expression of both molecules. In vitro DNA binding, transactivation, Sumoylation and expression assays revealed that GA enhanced Sp1 binding to GC-boxes in the Prdx6 promoter and upregulated its transcription. Cell viability and intracellular redox status assays showed that LECs pretreated with GA gained resistance against oxidative stress-driven aberrant Sumoylation signaling. Overall, our study revealed an unprecedented role for GA in LECs and provided new mechanistic insights into the use of GA in rescuing LECs from aging/oxidative stress-evoked dysregulation of Sp1/Prdx6 protective molecules.

Association of donor and recipient SUMO4 rs237025 genetic variant with new-onset diabetes mellitus after liver transplantation in a Chinese population

BACKGROUNDS & AIMS

New-onset diabetes mellitus (NODM) is a common complication after liver transplantation (LT). The small ubiquitin-like modifier 4 (SUMO4) rs237025 polymorphism has been reported to be associated with type 2 diabetes mellitus (T2DM). In this study, we aimed to evaluate the association of donor and recipient SUMO4 rs237025 polymorphisms with NODM and the long-term consequences of NODM after LT.

METHODS

A total of 126 liver transplant patients were enrolled in the study. One single nucleotide polymorphism, SUMO4 rs237025, was genotyped in both donors and recipients.

RESULTS

Both donor and recipient SUMO4 rs237025 polymorphisms were found to be significantly associated with NODM after LT. In multivariate analysis, recipient age>50 years, tacrolimus trough concentrations>10ng/mL at 1month after LT, donor and recipient rs237025 genetic variant, and the combined donor and recipient rs237025 genetic variant were independent predictive factors of NODM. Area under the receiver operating characteristic curve (AUROC) analysis indicated the higher predictive ability of the model containing combined donor and recipient rs237025 polymorphisms than the clinical model (p=0.046). Furthermore, Kaplan-Meier survival analysis demonstrated that NODM was related to significantly poorer patient survival in comparison with non-NODM patients (p=0.041).

CONCLUSIONS

Both donor and recipient SUMO4 rs237025 polymorphisms contribute to the development of NODM after LT and NODM is a frequent complication that negatively affects patient survival.

Identification of key genes and pathways for peri-implantitis through the analysis of gene expression data

The present study attempted to identify potential key genes and pathways of peri-implantitis, and to investigate the possible mechanisms associated with it. An array data of GSE57631 was downloaded, including six samples of peri-implantitis tissue and two samples of normal tissue from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) in the peri-implantitis samples compared with normal ones were analyzed with the limma package. Moreover, Gene Ontology annotation and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses for DEGs were performed by DAVID. A protein-protein interaction (PPI) network was established using Cytoscape software, and significant modules were analyzed using Molecular Complex Detection. A total of 819 DEGs (759 upregulated and 60 downregulated) were identified in the peri-implantitis samples compared with normal ones. Moreover, the PPI network was constructed with 413 nodes and 1,114 protein pairs. Heat shock protein HSP90AA1 (90 kDa α, member 1), a hub node with higher node degrees in module 4, was significantly enriched in antigen processing, in the presentation pathway and nucleotide-binding oligomerization domain (NOD)-like receptor-signaling pathway. In addition, nuclear factor-κ-B1 (NFKB1) was enriched in the NOD-like receptor-signaling pathway in KEGG pathway enrichment analysis for upregulated genes. The proteasome is the most significant pathway in module 1 with the highest P-value. Therefore, the results of the present study suggested that HSP90AA1 and NFKB1 may be potential key genes, and the NOD-like receptor signaling pathway and proteasome may be potential pathways associated with peri-implantitis development.

The Correlation of Increased CRP Levels with NFKB1 and TLR2 Polymorphisms in the Case of Morbid Obesity

Morbid obesity (MO) is associated with an increase in circulating levels of systemic acute phase proteins such as C-reactive protein (CRP). Toll-like receptor is possible candidate for inflammatory responses which is mainly mediated by NFKB1. The aim of this study was to investigate the relationship between NFKB1 and Toll-like receptor (TLR) 2 polymorphisms and the risk of MO in a Turkish population in the context of CRP serum levels which may contribute to susceptibility to the disease. We analysed the distribution of NFKB1-94 ins/del ATTG rs28362491 and TLR2 Arg753Gln rs5743708 polymorphisms using PCR-RFLP method and CRP serum levels using ELISA method in 213 MO and 200 healthy controls. The frequency of the ins/ins genotype and ins allele of rs28362491 was significantly higher in the patients compared to control group (P: 0.0309; P: 0.0421, respectively). Additionally, the frequency of GG genotype and G allele of rs5743708 was found to be statistically higher in the patient group (P: 0.0421; P < 0.0001, respectively). In addition, serum CRP levels (>20 mg/l) in MO patients with ins/ins genotype were significantly higher than in patients with del/ins genotype (P: 0.0309). Serum CRP levels were also higher in MO patients with GG genotype and G allele (P: 0.0001). According to combined analysis, the wild type of rs28362491 and rs5743708 polymorphisms (ins/ins/GG genotype) was also significantly higher in the patient group versus the control group when compared with the combined ins/ins/GA and del/ins/GA genotype (P < 0.0001). Therefore, our findings suggest that rs28362491 and rs5743708 polymorphisms were significantly associated with MO disease through acting by modulating serum CRP levels.

Association of NFKB1 and NFKBIA polymorphisms in relation to susceptibility of Behçet's disease

Behçet's disease (BD) is a chronic inflammatory autoimmune disease. Although raised levels of proinflammatory cytokines in BD have been reported, the pathogenesis is still unknown. The aim of this study was to investigate the association of NFKB1 and NFKBIA polymorphisms and their single and combined analysis effects on susceptibility of BD in Turkish population. We analysed the distribution of NFKB1 -94 ins/del ATTG (rs28362491) and NFKBIA 3' UTR A→G (rs696) polymorphisms using PCR-RFLP method in 89 patients with BD and 190 controls in this population. Statistical analysis of the results was performed by calculating OR, and 95% CI via χ(2) test and using Bonferroni correction. According to the significant results of both single and combined genotype analysis, the frequencies of ins/ins genotype and ins allele of rs28362491 were significantly higher in patients with BD (Pc = 0.003, 0.004, respectively). Also, higher frequencies of the rs696 variant containing AA genotype was found in patients with BD (Pc = 0.0033), whereas no statistical significant differences in distribution of the alleles of rs696 polymorphism in patients and controls. In addition, according to the combined genotype analysis, the wild type of both rs28362491 and rs696 polymorphisms (ins/ins/AA genotype) was also significantly higher in BD cases (Pc = 0.044). Our findings prove that both single and combined genotype analysis of rs28362491 and rs696 polymorphisms indicate that the wild genotypes of both two SNPs (ins/ins and AA genotypes) and ins/ins/AA combined genotype are strongly associated with enhanced risk of BD in a Turkish population.

Immune response to chemically modified proteome

Both enzymatic and nonenzymatic PTMs of proteins involve chemical modifications. Some of these modifications are prerequisite for the normal functioning of cell, while other chemical modifications render the proteins as "neo-self" antigens, which are recognized as "non-self" leading to aberrant cellular and humoral immune responses. However, these modifications could be a secondary effect of autoimmune diseases, as in the case of type I diabetes, hyperglycemia leads to protein glycation. The enigma of chemical modifications and immune response is akin to the "chick-and-egg" paradox. Nevertheless, chemical modifications regulate immune response. In some of the well-known autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, and multiple sclerosis, chemically modified proteins act as autoantigens forming immune complexes. In some instances, chemical modifications are also involved in regulating immune response during pathogen infection. Further, the usefulness of proteomic analysis of immune complexes is briefly discussed.

The SUMOylation of zinc-fingers and homeoboxes 1 (ZHX1) by Ubc9 regulates its stability and transcriptional repression activity

Zinc-fingers and homeoboxes protein 1 (ZHX1) belongs to the ZF (zinc-fingers) class of homeodomain transcription factors, and its function remains largely unknown. ZHX1 has been previously found to interact with the activation domain of the nuclear factor Y subunit A (NFYA) and to have a transcriptional repression activity. Here, we report that the SUMO-E2 conjugating enzyme Ubc9 was identified to interact with ZHX1 by an interaction screen using a yeast two-hybrid system. This interaction was confirmed by co-immunoprecipitation and co-localization assays. Further study showed that ZHX1 is SUMOylated by Ubc9 with SUMO1 at the sites K159, K454, and K626. Furthermore, we demonstrated that the SUMOylation of ZHX1 regulated the stability, ubiquitination and transcriptional activity of ZHX1.

Impact of NF-κB gene polymorphism on allograft outcome in Hispanic renal transplant recipients

BACKGROUND

The dimeric NF-κB transcription factors play critical roles in diverse cellular processes including adaptive and innate immunity, cell differentiation, proliferation and apoptosis. It regulates the expression of numerous genes that play a key role in the inflammatory response during kidney allograft rejection. This study aims to determine the association of NF-κB gene polymorphisms with allograft outcomes in the Hispanic renal transplant recipients.

METHODS

A total of 607 Hispanic renal transplant recipients at St. Vincent Medical Center between 2001 and 2010 were included in this study. The NF-κB genotypes were studied along with clinical data. In the case of NF-κB genotypes, the following single nucleotide polymorphisms (SNPs) were included: NF-κB1 (rs3774959, rs3774932, rs3774937, rs230526, rs230519), NF-κB2 (rs1056890, rs7897947, rs12769316) and NF-κB inducing kinase (NIK) (rs9908330, rs7222094). The association of each genotype with renal allograft survival and acute rejection was evaluated.

RESULTS

NF-κB1 (rs3774937) CC genotype showed protective association with allograft rejection (OR=0.66, 95% CI=0.44-0.99, p=0.04). There was a significant increase in allograft survival time associated with the NF-κB1 (rs3774959) A allele (OR=0.76, 95% CI=0.60-0.98, p=0.03) while GG genotype was associated with a higher risk of graft failure (OR=1.51, 95% CI=1.02-2.21, p=0.03). There were no associations between polymorphic markers in NF-κB2 and NIK genes with allograft survival or acute rejection. Among non-genetic factors, we found that the use of tacrolimus, a deceased donor, delayed graft function and acute rejection were associated with allograft failure.

CONCLUSION

The result of present study suggests that NF-κB1 gene polymorphisms may determine the incidence of acute rejection or graft survival among Hispanic allograft recipients.

No association of the SUMO4 polymorphism M55V variant in type 2 diabetes in Iranian subjects

INTRODUCTION

Diabetes mellitus incidence has an increasing rate and it's genetic aspect is an important approach as a risk factor and predictive value in this disorder. In some population, SUMO4, a regulator of NF-κB, gene polymorphism is associated with diabetes. A single-nucleotide polymorphism was detected in SUMO4; substituting a highly conserved methionine with a valine residue (M55V). We studied the association between M55V polymorphism in the SUMO4 gene insusceptibility of type 2 diabetes in patients with type 2 diabetes.

MATERIALS AND METHODS

Participants were 50 patients with type 2 diabetes and 50 control Iranian subjects. Genotyping was done using polymorphism chain reaction (PCR) technique and subsequent cleavage by restriction endonuclease (RFLP) for the M55V SUMO4 gene variant.

RESULTS

The frequency of SUMO4 AA, AG and GG were 13%, 25% and 12% in control group and 20%, 22%, 18% in the type 2 diabetes patients respectively. The SUMO4 M55V variant was not associated with the susceptibility of type 2 diabetes.

CONCLUSION

The study indicates that the SUMO4 gene M55V variant was not associated with the susceptibility of the type 2 diabetes polymorphism.

Association of SUMO4 M55V polymorphism with type 1 diabetes in Chinese children

OBJECTIVE

A functional polymorphism at codon 55 of the small ubiquitin like modifier 4 (SUMO4) gene (methionine to valine; M55V) was recently found to be associated with type 1 diabetes mellitus mainly in Asian populations (T1D). In the present study, we aimed to investigate whether this locus also contributes to the genetic susceptiblity to type 1 diabetes in Chinese.

RESEARCH DESIGN AND METHODS

A case-control study was performed using genomic DNA samples from 165 unrelated Chinese childhood T1D subjects and 160 normal blood donors. The SUMO4 M55V single nucleotide polymorphism (SNP) was genotyped using polymerase chain reaction (PCR) amplification followed by digestion with the restriction enzyme Mse I.

RESULTS

The frequencies of SUMO4 163G allele were significantly increased in T1D patients (38. 2% vs. healthy control subjects 28.7%, P < 0.05, OR = 1.51, 95% CI 1.03-2.13). SUMO4 163 GG genotype was also significantly increased in the T1D patients (17% vs. healthy control subjects 8%, P < 0.05).

CONCLUSIONS

This study indicates that the SUMO4 gene M55V variant is associated with the genetic susceptibility of T1D in Chinese children.

Analyses of multiple single-nucleotide polymorphisms in the SUMO4/IDDM5 region in affected sib-pair families with type I diabetes

Previous studies suggested that the SUMO4 gene, located in the IDDM5 interval on chromosome 6q25, was associated with type I diabetes (T1D) and several other autoimmune diseases. Subsequent analyses of the SUMO4 variants with T1D suggested that the association was stronger and more consistent in the Asian populations. In addition, considerable heterogeneity has been observed in the Caucasian populations. In this report, a 40-kb genomic interval including the SUMO4 gene was tagged with 15 single-nucleotide polymorphisms. A total of 2317 affected sib-pair families from the Type I Diabetes Genetic Consortium were genotyped using both the Illumina and Sequenom genotyping platforms. In these Caucasian families, we found little evidence supporting an association between SUMO4 and T1D.

A functional insertion/deletion polymorphism in the promoter region of the NFKB1 gene increases susceptibility for prostate cancer

Among men, cancers of the prostate, lung and bronchus, and colon and rectum account for about 50% of all newly diagnosed cancers, and prostate cancer alone accounts for about 25% of incident cases. Nuclear factor-kappaB (NF-kappaB)-activation plays a critical role in prostate cancer by NF-kappaB inhibitor kinase beta pathway-mediated inflammatory-induced tumorigenesis. A functional insertion/deletion polymorphism (-94 insertion/deletion ATTG) in the promoter of the NFKB1 gene, which encodes the p50 subunit of NF-kappaB, was identified recently. A total of 117 prostate cancer patients and 143 control subjects were recruited in this study. The NFKB1 -94 insertion/deletion ATTG genotype was determined using polymerase chain reaction-polyacrylamide gel electrophoresis. The frequency of the ATTG(2) allele in prostate cancer patients was significantly higher than that in the controls (63.7 vs. 54.5%; P=0.035, OR=1.461). Prostate cancer patients with a history of prostatitis have a 2.275 times higher risk for prostate cancer, compared to the control group (P=0.001). The functional NFKB1 promoter polymorphism is associated with increased risk of prostate cancer.

Functional polymorphism of the NFKB1 gene promoter is related to the risk of dilated cardiomyopathy

Background

Previous studies in experimental and human heart failure showed that nuclear factor kappa B (NF-κB) is chronically activated in cardiac myocytes, suggesting an important involvement of NF-κB in the cardiac remodeling process. A common insertion/deletion (-94 insertion/deletion ATTG, rs28362491) located between two putative key promoter regulatory elements in the NFKB1 gene was identified which seems to be the first potential functional NFKB1 genetic variation. The main goal of the present investigation was to investigate the NFKB1 -94 insertion/deletion ATTG polymorphism in relation to risk of dilated cardiomyopathy (DCM).

Methods

A total of 177 DCM patients and 203 control subjects were successfully investigated. The NFKB1 -94 insertion/deletion ATTG polymorphism was genotyped by using PCR-PAGE.

Results

Genotype frequency of NFKB1 -94 insertion/deletion ATTG polymorphism in DCM patients was significantly different from that in control subjects (P = 0.015) and the ATTG₂ carrier (ATTG₁/ATTG₂ + ATTG₂/ATTG₂) was susceptible to DCM.

Conclusion

Our data suggested that NFKB1 -94 insertion/deletion ATTG polymorphism is associated with DCM.

Functional polymorphism of NFKB1 promoter may correlate to the susceptibility of gastric cancer in aged patients

BACKGROUND

Activated nuclear factor-kappaB (NF-kappaB) is associated reportedly with the pathogenesis of numerous malignancies. This study investigated whether a common insertion (ins)/deletion (del) polymorphism (-94 ins/del ATTG) in the NFKB1 promoter is associated with susceptibility to gastric cancer and its tumor behavior.

METHODS

Blood samples from 182 gastric cancer patients and 116 controls were examined by polymerase chain reaction-based genotyping. Allelotype and genotype (polymorphism) of NFKB1 promoter in gastric cancer patients were analyzed with controls and patients' clinicopathologic factors to evaluate their association using a multivariate analytical model.

RESULTS

The mean ages of patients and controls were 65.7 +/- 12.8, and 64.9 +/- 8.8 years old, respectively. Sex ratios (male to female) were 2.7:1 and 2.2:1, respectively. Insertion allelotype, genotypes with ins/ins, as well as ins allele carrier (ins/ins+ ins/del) were significantly greater in gastric cancer patients than in controls, especially in patients >65 years old, but not in younger patients. The polymorphism did not correlate with clinicopathologic factors and patient survival.

CONCLUSION

NFKB1 could be a susceptible gene for gastric cancer and its functional polymorphism in promoter is associated with the risk of gastric cancer, particularly in aged patients.

Association of NFKB1 -94ins/del ATTG promoter polymorphism with susceptibility to and phenotype of Graves' disease

Recently, a functional polymorphism in the NFKB1 gene promoter (-94ins/del ATTG) has been identified and associated with chronic inflammatory diseases. The aim of this study was to analyze the association of NFKB1 polymorphism with susceptibility to and phenotype of Graves' disease (GD). The initial case-control association study, performed in a Polish-Warsaw cohort (388 GD patients and 688 controls), was followed by the two replication studies performed in Polish-Gliwice and Japanese-Kurume cohorts (198 GD patients and 194 controls, and 424 GD patients and 222 controls, respectively). The frequency of the -94del ATTG (D) allele was increased in GD compared to controls in Warsaw cohort. This finding was replicated in Gliwice cohort. Combining both Polish-Caucasian cohorts showed that the NFKB1 polymorphism was significantly associated with susceptibility to GD with a codominant mode of inheritance (P=0.00005; OR=1.37 (1.18-1.60)). No association with GD was found in Japanese cohort. However, subgroup analysis in Japanese GD patients revealed a correlation between the NFKB1genotype and the development of ophthalmopathy (P=0.009; OR=1.49 (1.10-2.01)), and the age of disease onset (P=0.009; OR=1.45 (1.09-1.91)). Our results suggest that NFKB1 -94ins/del ATTG polymorphism may be associated with susceptibility to and/or phenotype of GD.

SUMO4 M55V polymorphism affects susceptibility to type I diabetes in HLA DR3- and DR4-positive Swedish patients

SUMO4 M55V, located in IDDM5, has been a focus for debate because of its association to type I diabetes (TIDM) in Asians but not in Caucasians. The current study aims to test the significance of M55V association to TIDM in a large cohort of Swedish Caucasians, and to test whether M55V is associated in those carrying human leukocyte antigen (HLA) class II molecules. A total of 673 TIDM patients and 535 age- and sex-matched healthy controls were included in the study. PCR-RFLP was performed to identify the genotype and allele variations. Our data suggest that SUMO4 M55V is not associated with susceptibility to TIDM by itself. When we stratified our patients and controls based on heterozygosity for HLA-DR3/DR4 and SUMO4 genotypes, we found that presence of SUMO4 GG increased further the relative risk conferred by HLA-DR3/DR4 to TIDM, whereas SUMO4 AA decreased the risk. From the current study, we conclude that SUMO4 M55V is associated with TIDM in association with high-risk HLA-DR3 and DR4, but not by itself.

Affinity chromatography of native SUMO proteins using His-tagged recombinant UBC9 bound to Co2+-charged talon resin

Four small ubiquitin-related modifier (SUMO) genes have been identified in humans. The recently identified SUMO4 was detected in mRNA transcripts from HEK293 cells, and human kidney and spleen tissue and may be involved in regulation of NF-kappaB and susceptibility to autoimmune diseases. However, identification and characterization of a native SUMO4 protein has not yet been reported. Here, we analyzed for the presence of native SUMO proteins in HEK293 cells and human kidney tissue using an affinity purification procedure using a UBC9 matrix followed by mass spectroscopy analyses for SUMO-specific peptides. Identification by mass spectroscopy of peptides generated by Trypsin and Lys-C digestion did reveal peptides unique to SUMO1 and SUMO2/3, but not SUMO4. In control experiments, SUMO4 prepared by recombinant methods was isolated and even enriched by our UBC9 affinity purification. Thus, SUMO4 protein appears to be either in extremely low abundance in human kidney or HEK293 cells or it is not present at all. It remains possible that SUMO4 protein is more abundant in other cell types or can be induced by hormonal or environmental challenges and the procedures reported here should be extremely useful for detecting native SUMO4. Furthermore, using His-tagged recombinant proteins bound to Co(2+)-charged Talon resin has general applicability to isolate native proteins that have strong non-covalent interactions with the resin-bound His-tagged proteins.

No association of the NFKB1 insertion/deletion promoter polymorphism with survival in colorectal and renal cell carcinoma as well as disease progression in B-cell chronic lymphocytic leukemia

PURPOSE

Nuclear factor-kappaB (NF-kappaB) is an inducible transcription factor that plays a major role in the regulation of genes involved in immune and inflammatory response. Activation of NF-kappaB has also been associated with apoptosis and proliferation, thereby potentially also controlling oncogenesis. A functional insertion/deletion polymorphism has been identified in the promoter region of NFKB1, which apparently controls the transcription of NF-kappaB. The purpose of this study was, therefore, to investigate associations of the -94ins/delATTG polymorphism with susceptibility and survival of patients with different types of cancer.

EXPERIMENTAL DESIGN

Genotype distributions in patients with colorectal carcinoma (n=139), B-cell chronic lymphocytic leukemia (n=72) and clear cell renal cell carcinoma (n=140), and in controls (n=307) were analyzed by pyrosequencing and compared with each other as well as associated with clinico-pathological parameters and demographic data.

RESULTS

No statistically significant differences in both allele and genotype frequencies were observed between patients and healthy controls. Likewise, no association between -94ins/delATTG alleles and survival or disease progression was noticed.

CONCLUSION

These results suggest that the NFKB1 promoter polymorphism has no effect on risk and course of disease in the three cancer entities that were analyzed.

Genetic epidemiology of type 1 diabetes

The evidence that there is clinical heterogeneity of type 1 diabetes is reviewed and the implications for genetic studies are discussed. In the past year, genome-wide linkage analysis of 1435 multiplex families was reported. Additionally, confirmed evidence for association of specific markers at two loci (PTPN22, OAS1) as well as failure to replicate three others (IL12B, SUMO4, PAX4) is discussed. Some common themes are identified and suggestions for improvements are made. We look forward to the results from genome-wide association studies.

NFkappaB1 gene does not affect type 1 diabetes predisposition in a Spanish population

The chromosomal location of the NFkappaB1 gene on 4q, a region linked to type 1 diabetes (T1D), together with the observed resistance to T1D of NFkappaB1-deficient mice, suggests its potential role as candidate gene increasing diabetes predisposition. Previous association studies in diverse populations yielded inconclusive results. Two polymorphisms in the promoter region of the NFkappaB1 gene have been studied: a functional -94ins/delATTG regulating the gene expression and a very informative CA-repeat microsatellite. A strong association with the latter was reported in British population but could not be replicated in Danish families. No evidence of association was detected for those genetic markers in 270 Spanish T1D patients and 484 healthy ethnically matched controls. Therefore, it seems that this gene plays no major role in T1D predisposition.

Genetic progress towards the molecular basis of autoimmunity

The past few years have seen the identification of PTPN22 and the confirmation of CTLA-4 as common autoimmune disease genes. Together with MHC and INS, these developments have increased the collection of confirmed susceptibility loci for autoimmunity. In this article, the latest developments related to these genes and to other recently studied candidate autoimmune susceptibility loci (PDCD1, FCRL3, SUMO4, CD25, PADI4 and SLC22A4) are reviewed. Collectively, these genes strongly indicate that aberrant inhibition of the signalling cascade initiated by activation of the T-cell receptor is involved in the aetiology of autoimmune disease. However, much basic genetic, molecular and clinical research is still needed to help us fully understand the underlying mechanisms of autoimmunity and how these translate into prognosis or therapy.

Genetic susceptibility to type 1 diabetes

The recent discovery of PTPN22 as a novel susceptibility gene in human type 1 diabetes and continued progress in defining genes in animal models of the disease mark a fruitful period in the field of type 1 diabetes genetics. In addition, the similarities of the genetic and functional aspects across species have been substantiated. Future genome-wide association studies will reveal more loci, each providing a piece to the genetic puzzle of autoimmune disease.

Genetic heterogeneity in association of the SUMO4 M55V variant with susceptibility to type 1 diabetes

Association studies are a potentially powerful approach to identifying susceptibility variants for common multifactorial diseases such as type 1 diabetes, but the results are not always consistently reproducible. The IDDM5 locus has recently been narrowed to an approximately 200-kb interval on chromosome 6q25 by two independent groups. These studies demonstrated that alleles at markers in the mitogen-activating protein kinase 7 interacting protein 2 (MAP3K7IP2)/SUMO4 region were associated with susceptibility to type 1 diabetes. Subsequent studies, however, showed inconsistency in the association of the SUMO4 gene with type 1 diabetes. To clarify the contribution of the M55V polymorphism of the SUMO4 gene to type 1 diabetes susceptibility, 541 type 1 diabetic patients and 768 control subjects were studied in Asian populations. The M55V polymorphism was significantly associated with type 1 diabetes in Asian populations (summary odds ratio [OR] 1.46, P = 0.00083, Mantel-Haenszel test). Meta-analysis of published studies and the present data confirmed a highly significant association in Asian populations (summary OR 1.29, P = 7.0 x 10(-6)) but indicated heterogeneity in the genetic effect of the SUMO4/MAP3K7IP2 locus on type 1 diabetes among diverse ethnic groups. These data indicate that the MAP3K7IP2/SUMO4 locus in the IDDM5 interval is associated with type 1 diabetes in Asian populations.

The genetics of type 1 diabetes: lessons learned and future challenges

It has been more than 30 years since the first evidence was published suggesting the involvement of a specific chromosomal region, HLA, in modulating the risk for type 1 diabetes (T1D). In the intervening years, what have we learned regarding the identities of specific loci that modulate T1D risk, and what lessons have these studies provided that might be helpful in finding and characterizing additional susceptibility loci both for T1D and other autoimmune disorders? In the following review, we briefly address these issues.

A proline-90 residue unique to SUMO-4 prevents maturation and sumoylation

Four small ubiquitin-related modifier (SUMO) genes have been identified in humans. However, little is known about the basic biology of SUMO-4. Here, we report that SUMO-4 differs from SUMO-1, -2, and -3 in that the maturation process of SUMO-4 to active form containing C-terminal di-glycine residues is inhibited by a unique proline residue located at position 90 (Pro-90). Although, both the hydrolase and isopeptidase activities of SUMO peptidases are significantly diminished by Pro-90 as compared to Gln-90 (glutamine) in mutated SUMO genes, only the defective hydrolase activity appears to be biologically relevant. Native SUMO-4, thus, appears to be unable to form covalent isopeptide bonds with substrates. A biological role of SUMO-4, through non-covalent interactions is proposed.