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

SUMO4 Gene SNP rs237025 and the Synergistic Effect With Weight Management: A Study of Risk Factors and Interventions for MetS

Aim: Metabolic Syndrome (MetS) is widespread across the world. Gene targeted therapy and risk management are promising approaches for MetS intervention. SUMO4 gene rs237025 polymorphism is related to an increased risk of diabetes, therefore, it is considered a target for the gene polymorphism research of MetS.

Methods: A case-control study was performed to study the interaction of rs237025 with MetS and the components of MetS. A 5-years follow-up survey was carried out to elucidate the crosstalk between rs237025 and weight management, and the synergistic effect on MetS.

Results: A total of 1,008 MetS patients and 1,047 controls were recruited in this research. By cross-section study, we find that rs237025 is an independent risk factor for increased Waist Circumference (WC), elevated Triglyceride (TG), elevated Fasting Plasma Glucose (FPG), and MetS. Cross-over analysis identifies the interaction of rs237025 and weight management as a risk factor for MetS, the synergistic effects of rs237025 and weight management are negative to WC, TG, and High-density Lipoprotein-cholesterol (HDL-c).

Conclusion:SUMO4 gene rs237025 is related to increased risk of MetS, weight management is essential to MetS intervention, especially for patients with rs237025 polymorphism.

β-Cell failure in diabetes: Common susceptibility and mechanisms shared between type 1 and type 2 diabetes

Diabetes mellitus is etiologically classified into type 1, type 2 and other types of diabetes. Despite distinct etiologies and pathogenesis of these subtypes, many studies have suggested the presence of shared susceptibilities and underlying mechanisms in β-cell failure among different types of diabetes. Understanding these susceptibilities and mechanisms can help in the development of therapeutic strategies regardless of the diabetes subtype. In this review, we discuss recent evidence indicating the shared genetic susceptibilities and common molecular mechanisms between type 1, type 2 and other types of diabetes, and highlight the future prospects as well.

Deciphering the SUMO code in the kidney

SUMOylation of proteins is an important regulatory element in modulating protein function and has been implicated in the pathogenesis of numerous human diseases such as cancers, neurodegenerative diseases, brain injuries, diabetes, and familial dilated cardiomyopathy. Growing evidence has pointed to a significant role of SUMO in kidney diseases such as DN, RCC, nephritis, AKI, hypertonic stress and nephrolithiasis. Recently, emerging studies in podocytes demonstrated that SUMO might have a protective role against podocyte apoptosis. However, the SUMO code responsible for beneficial outcome in the kidney remains to be decrypted. Our recent experiments have revealed that the expression of both SUMO and SUMOylated proteins is appreciably elevated in hypoxia‐induced tubular epithelial cells (TECs) as well as in the unilateral ureteric obstruction (UUO) mouse model, suggesting a role of SUMO in TECs injury and renal fibrosis. In this review, we attempt to decipher the SUMO code in the development of kidney diseases by summarizing the defined function of SUMO and looking forward to the potential role of SUMO in kidney diseases, especially in the pathology of renal fibrosis and CKD, with the goal of developing strategies that maximize correct interpretation in clinical therapy and prognosis.

Demographic and clinical characteristics of patients with type 1 diabetes mellitus: A multicenter registry study in Guangdong, China

BACKGROUND

A lack of demographic and clinical data hinders efforts of health care providers in China to support patients with type 1 diabetes mellitus (T1D). Therefore, the aim of the present retrospective study was to provide an overview of the demographic and clinical characteristics of Chinese patients with T1D.

METHODS

Hospital medical records of patients with T1D (diagnosed between January 2000 and December 2011) in 105 secondary and tertiary hospitals across Guangdong province were reviewed. Data were collected on patient age at diagnosis, presentations at onset, physical examination, and diabetes management.

RESULTS

In all, 3173 patients diagnosed with T1D between January 2000 and December 2011 were included in the study (46.2% female). The median age at diagnosis was 27.5 years (interquartile range [IQR] 18.0-38.0) years and the median body mass index (BMI) at onset was 19.6 kg/m² (IQR 17.4-21.8 kg/m² ). Among adult patients, 0.9% were obese, 6.6% were overweight, 62.3% were normal weight, and 30.3 % were underweight. The prevalence of diabetic ketoacidosis (DKA) at onset was 50.1%. The proportion of patients with retinopathy, nephropathy, and neuropathy was 8.1%, 20.7 %, and 11.1%, respectively.

CONCLUSION

The adult-onset form of T1D is not rare in China. The registry participants were characterized by older age at onset, lower BMI, and a higher prevalence of DKA at onset compared with those in regions with a high incidence of T1D, such as northern Europe. These findings contribute to a better understanding of the heterogeneity of T1D in different populations and so will help healthcare providers to develop management models that are more suitable for these patients.

Genetics and pathogenesis of type 1 diabetes: prospects for prevention and intervention

Type 1 diabetes is etiologically a multifactorial disease caused by a complex interaction of genetic and environmental factors, with the former consisting of multiple susceptibility genes. Identification of genes conferring susceptibility to type 1 diabetes would clarify etiological pathways in the development and progression of type 1 diabetes, leading to the establishment of effective methods for prevention and intervention of the disease. Among multiple susceptibility genes, HLA and INS are particularly important because of their contribution to tissue specificity in the autoimmune process. DRB1*04:05-DQB1*04:01 is associated with autoimmune type 1 diabetes, idiopathic fulminant type 1 diabetes and anti-islet autoimmunity in autoimmune thyroid diseases, suggesting that this haplotype is associated with beta-cell specificity in autoimmune diseases. Genes involved in the expression of insulin in the thymus contribute to beta-cell-specific autoimmune mechanisms in type 1 diabetes. These genes and pathways are important targets for tissue-specific prevention and intervention of type 1 diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00176.x, 2011).

Network medicine analysis of chondrocyte proteins towards new treatments of osteoarthritis

Osteoarthritis (OA) is a progressive disorder with high incidence in the ageing human population that still has no treatment currently. This disorder induces the breakdown of articular cartilage, leading to the exposure and damage of bone surfaces. For a global understanding of OA development, the systematic integration of known OA-related proteins with protein-protein interaction (PPI) networks is required. In this work, the OA-related interactome was reconstructed using multiple data sources to have the most up-to-date information on OA-related proteins and their interactions. We then combined emergent concepts in network medicine to detect new unclassified OA-related proteins. The mapping of known OA-related proteins with PPI networks showed that these proteins are locally connected to each other and agglomerated in a large component. To expand this module, we applied a diffusion-based algorithm that probabilistically induces more searches in the vicinity of the seed OA-related proteins. As a result, the 10 topmost ranked proteins were connected to the OA disease module, supporting the local hypothesis. We computed structural modules and selected those that had the highest enrichment of OA-related proteins. The identified molecules show a link between structural topology and disease dysfunctionality. Interestingly, the protein Q6EEV6 was highlighted for OA association by both methods, reinforcing the potential involvement of this protein. These results suggest that similar disease-connected modules may exist in different human disorders, which could lead to systematic identification of genes or proteins that have a joint role in specific disease phenotypes.

Acidic residue Glu199 increases SUMOylation level of nuclear hormone receptor NR5A1

Steroidogenic factor 1 (NR5A1/SF1) is a well-known master regulator in controlling adrenal and sexual development, as well as regulating numerous genes involved in adrenal and gonadal steroidogenesis. Several studies including ours have demonstrated that NR5A1 can be SUMOylated on lysine 194 (K194, the major site) and lysine 119 (K119, the minor site), and the cycle of SUMOylation regulates NR5A1’s transcriptional activity. An extended consensus negatively charged amino acid-dependent SUMOylation motif (NDSM) enhances the specificity of substrate modification by SUMO has been reported; however, the mechanism of NDSM for NR5A1 remains to be clarified. In this study, we investigated the functional significance of the acidic residue located downstream from the core consensus SUMO site of NR5A1. Here we report that E199A (glutamic acid was replaced with alanine) of NR5A1 reduced, but not completely abolished, its SUMOylation level. We next characterized the functional role of NR5A1 E199A on target gene expression and protein levels. We found that E199A alone, as well as combination with K194R, increased Mc2r and Cyp19a1 reporter activities. Moreover, E199A alone as well as combination with K194R enhanced NR5A1-mediated STAR protein levels in mouse adrenocortical cancer Y1 cells. We also observed that E199A increased interaction of NR5A1 with CDK7 and SRC1. Overall, we provide the evidence that the acidic residue (E199) located downstream from the core consensus SUMO site of NR5A1 is, at least in part, required for SUMOylation of NR5A1 and for its mediated target gene and protein expression.

Polymorphism M55V in gene encoding small ubiquitin-like modifier 4 (SUMO4) protein associates with susceptibility to type 1 (and type 2) diabetes

BACKGROUND

The association between small ubiquitin-like modifier 4 (SUMO4) gene polymorphism and type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) has been investigated in several studies. We conducted a meta-analysis to evaluate the association of SUMO4 gene polymorphism with T1DM and T2DM susceptibility.

METHODS

A meta-analysis was performed on the published studies before August 2011. The association of SUMO4 M55V polymorphism with T1DM and T2DM was evaluated. Meta-analysis was performed for genotypes AA versus GG, AA versus AG, AA versus AG + GG and A allele versus G allele in a fixed/random effect model. The combined odds ratio (OR) with 95% confidence interval (95% CI) was calculated to estimate the strength of the association.

RESULTS

Sixteen case-control studies including 9190 cases and 10 456 healthy controls were included. T1DM patients were divided into Asian and Caucasian subgroup. We detected a significant association of SUMO4 M55V polymorphism with T1DM in Asian population (A versus G: OR = 0.79, 95%CI = 0.72-0.86, p = 0.000) and a significant association of SUMO4 M55V polymorphism with T1DM in Caucasian population (A versus G: OR = 0.84, 95%CI = 0.73-0.97, p = 0.007). Included T2DM patients were all Asian. Meanwhile, a significant association of SUMO4 M55V polymorphism with T2DM was also found (A versus G: OR = 0.86, 95%CI = 0.79-0.94, p = 0.001).

CONCLUSIONS

Our study demonstrates significant associations of SUMO4 M55V polymorphism with T1DM in Asian and Caucasian population and with T2DM in Asian population.

Association between the SUMO4 M55V (A163G) polymorphism and susceptibility to type 1 diabetes: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether the SUMO4 M55V (A163G) polymorphism confers susceptibility to type 1 diabetes (T1D).

METHODS

A meta-analysis was conducted on the association between the SUMO4 M55V polymorphism and T1D using; (1) allelic contrast (G vs. A), and the (2) recessive (GG vs. GA+AA), (3) dominant (GG+GA vs. AA), and (4) additive models (GG vs. AA).

RESULTS

Thirteen separate studies were considered in the meta-analysis, which in total included 5915 patients and 6660 controls, and five European and eight Asian sample populations. Europeans had a higher prevalence of the G allele than Asians (50.4% vs. 30.2%). Meta-analysis of the SUMO4 M55V polymorphism showed an association between T1D and the SUMO4 G allele in all study subjects (OR=1.236, 95% CI=1.112-1.373, p=7.9×10(-6)), and stratification by ethnicity indicated a highly significant association between the SUMO4 G allele and T1D in Asians (OR=1.303, 95% CI=1.169-1.452, p=1.78×10(-7)) and a marginal association with T1D in Europeans (OR=1.177, 95% CI=1.000-1.386, p=0.050). Furthermore, significant associations were found between the SUMO4 M55V polymorphism and T1D and all study subjects, Europeans, and Asians using the dominant model (OR=1.239, 95% CI=1.144-1.342, p=1.4×10(-8); OR=1.156, 95% CI=1.051-1.271, p=0.003; OR=1.461, 95% CI=1.262-1.691, p=3.8×10(-8), respectively).

CONCLUSIONS

This meta-analysis indicates that the SUMO4 M55V polymorphism confers susceptibility to T1D in Asians and Europeans.

Erratum to ‘‘Characterization of the regulatory roles of the SUMO

BACKGROUND

Type 1 diabetes is a multi-factorial autoimmune disease that results from the destruction of insulin-producing β cells of the pancreas; both genetic and environmental factors are thought to contribute to its development. Recently, a novel gene encoding small ubiquitin-like modifier protein 4 (SUMO4) was cloned and a single nucleotide substitution (M55V) was found to be strongly associated with type 1 diabetes. SUMO4 was shown to interact with IκBα and inhibit NFκB transcriptional activity. The M55V substitution of SUMO4 may affect its ability to modify IκBα by sumoylation, and so lead to activation of NFκB and transcription of genes implicated in the development of type 1 diabetes. However, the effects of sumoylation on immune cells are poorly understood.

METHODS

Human SUMO1, 2, 3, 4 and mouse SUMO2 (mSUMO2) were cloned and overexpressed in T and B cells using retroviral transduction. We then investigated whether SUMO overexpression affected their functions in vitro. To study the function of mSUMO2 in vivo, we made transgenic mice overexpressing mSUMO2 in T cells and pancreatic β cells and compared them with transgenic mice expressing a super-repressor of NFκB (a dominant negative form of NFκB, IκBαΔN) in T cells. Diabetes was induced in the two groups of mice by i.p. injection of streptozotocin.

RESULTS

Human SUMO1, 2, 3, 4 and mSUMO2 were all found to negatively regulate the transcriptional activity of T and B cells. Supporting this idea, mSUMO2 overexpression in T cells suppressed the production of both Th1 and Th2 cytokines unlike T cells from the IκBαΔN mice. However, transgenic mice overexpressing mSUMO2 had the same susceptibility to diabetes as wild type whereas the mice overexpressing IκBαΔN Tg were completely protected against diabetes.

CONCLUSION

These results indicate that at least in T cells, whereas NFκB has pro-apoptotic activity, mSUMO2 plays a more complex role in the development of autoimmune diabetes. The relative influence of NFκB and sumoylation on the development of autoimmune diabetes in vivo may vary depending on the developmental stage and cell type.

Characterization of the regulatory roles of the SUMO

BACKGROUND

Type 1 diabetes is a multi-factorial autoimmune disease that results from the destruction of insulin-producing β cells of the pancreas; both genetic and environmental factors are thought to contribute to its development. Recently, a novel gene encoding small ubiquitin-like modifier protein 4 (SUMO4) was cloned and a single nucleotide substitution (M55V) was found to be strongly associated with type 1 diabetes. SUMO4 was shown to interact with IκBα and inhibit NFκB transcriptional activity. The M55V substitution of SUMO4 may affect its ability to modify IκBα by sumoylation, and so lead to activation of NFκB and transcription of genes implicated in the development of type 1 diabetes. However, the effects of sumoylation on immune cells are poorly understood.

METHODS

Human SUMO1, 2, 3, 4 and mouse SUMO2 (mSUMO2) were cloned and overexpressed in dendritic, T and B cells using retroviral transduction. We then investigated whether SUMO overexpression affected their functions in vitro. To study the function of mSUMO2 in vivo, we made transgenic mice overexpressing mSUMO2 in T cells and pancreatic β cells and compared them with transgenic mice expressing a super-repressor of NFκB (a dominant negative form of NFκB, IκBαΔN) in T cells. Diabetes was induced in the two groups of mice by i.p. injection of streptozotocin.

RESULTS

Human SUMO1, 2, 3, 4 and mSUMO2 were all found to negatively regulate the transcriptional activity of T, B and dendritic cells. Although mSUMO2 overexpression in dendritic cells did not alter the expression of major histocompatibility complex class II proteins or B7, IL-1, IL-6 and IL-7, IL-12 expression decreased, switching Th1-directed immune responses into Th2 responses. Unlike T cells from the IκBαΔN mice, mSUMO2 overexpression in T cells suppressed the production of both Th1 and Th2 cytokines. Whereas the mice overexpressing IκBαΔN were completely protected against diabetes, those expressing mSUMO2 had the same susceptibility to diabetes as wild type.

CONCLUSION

These results indicate that at least in T cells, whereas NFκB has pro-apoptotic activity, mSUMO2 plays a more complex role in the development of autoimmune diabetes. The relative influence of NFκB and sumoylation on the development of autoimmune diabetes in vivo may vary depending on the developmental stage and cell type.

Association of SUMO4 Met55Val variation with increased insulin resistance in newly diagnosed type 2 diabetes in a Chinese population

SUMO4 Met55Val variation was shown to be related to type 2 diabetes susceptibility and the vascular complications in Asian people. To further examine the related mechanisms, this study was designed to evaluate the association of SUMO4 Met55Val polymorphism with insulin resistance and β cell function in newly diagnosed type 2 diabetic patients in a Chinese population. Four hundred and twenty seven newly diagnosed type 2 diabetic patients were selected for SUMO4 Met55Val polymorphism genotype analysis. All subjects underwent a 75-g oral glucose tolerance test (OGTT) to estimate the insulin sensitivity and β cell function. Anthropometrics and a metabolic profile were used for phenotyping analysis. The results showed that the SUMO4 Met55Val polymorphism was associated with higher insulin resistance (P<0.001) and lower insulin sensitivity (P<0.001). Patients with GG genotype had higher levels of plasma glucose, insulin and C peptide. Insulin sensitivity index (ISI) was closely correlated with body mass index (BMI) in patients with GG genotype in comparison to the counterparts with AG or AA genotype (r= -0.504 vs. r= -0.430 vs. r= -0.340). Multiple regression linear analysis showed that SUMO4 Met55Val polymorphism was an independent determinant for insulin sensitivity (P=0.001), which, along with triglyceride, BMI and sex, could account for 20.1% of the variation in ISI. The result remained the same after adjusting for BMI and sex. No association was found between SUMO4 Met55Val polymorphism and β cell function (all P>0.05). It was concluded that SUMO4 Met55Val variant was associated with increased insulin resistance in Chinese patients with newly diagnosed type 2 diabetes.

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.

Small ubiquitin-like modifier-4 Met55Val polymorphism is associated with glycemic control of Type 2 diabetes mellitus in Taiwan

AIM

The development of Type 2 diabetes mellitus (T2DM) has been recognized to be associated with a combination of pancreatic beta-cell dysfunction and insulin resistance. Nuclear factor-kappaB (NF-kappaB) has been recognized as one central mediator in the reaction of inflammation and proapoptotic event in beta-cells. A functional polymorphism at the codon 55 (methionine to valine; A163G) of the small ubiquitin- like modifier-4 (SUMO4) gene may result in higher NF-kappaB activity. This study investigates whether this SUMO4 Met55Val polymorphism also contributes to the development of T2DM.

MATERIALS AND METHODS

The study was performed using genomic DNA samples from 574 Type 2 diabetic patients and 323 healthy controls. The SUMO4 Met55Val polymorphism was genotyped using allele-specific real-time PCR.

RESULTS

The frequency of the G allele (encoding Val55) was significantly higher in Type 2 diabetic patients and Type 2 diabetic patients with the GG genotype had higher hemoglobin A1c level. Multivariate logistic regression analysis revealed the genotype of GG and GA was an independent risk factor contributing to the development of T2DM.

CONCLUSION

This study suggests that in Taiwan the SUMO4 Met 55Val polymorphism is associated with susceptibility to T2DM and Type 2 diabetic patients with GG genotype have worse glycemic control.

Regulation of IkappaBalpha function and NF-kappaB signaling: AEBP1 is a novel proinflammatory mediator in macrophages

NF-κB comprises a family of transcription factors that are critically involved in various inflammatory processes. In this paper, the role of NF-κB in inflammation and atherosclerosis and the regulation of the NF-κB signaling pathway are summarized. The structure, function, and regulation of the NF-κB inhibitors, IκBα and IκBβ, are reviewed. The regulation of NF-κB activity by glucocorticoid receptor (GR) signaling and IκBα sumoylation is also discussed. This paper focuses on the recently reported regulatory function that adipocyte enhancer-binding protein 1 (AEBP1) exerts on NF-κB transcriptional activity in macrophages, in which AEBP1 manifests itself as a potent modulator of NF-κB via physical interaction with IκBα and a critical mediator of inflammation. Finally, we summarize the regulatory roles that recently identified IκBα-interacting proteins play in NF-κB signaling. Based on its proinflammatory roles in macrophages, AEBP1 is anticipated to serve as a therapeutic target towards the treatment of various inflammatory conditions and disorders.

The Type I Diabetes Genetics Consortium 'Rapid Response' family-based candidate gene study: strategy, genes selection, and main outcome

Candidate gene studies have long been the principal method for identification of susceptibility genes for type I diabetes (T1D), resulting in the discovery of HLA, INS, PTPN22, CTLA4, and IL2RA. However, many of the initial studies that relied on this strategy were largely underpowered, because of the limitations in genomic information and genotyping technology, as well as the limited size of available cohorts. The Type I Diabetes Genetic Consortium (T1DGC) has established resources to re-evaluate earlier reported genes associated with T1D, using its collection of 2298 Caucasian affected sib-pair families (with 11 159 individuals). A total of 382 single-nucleotide polymorphisms (SNPs) located in 21 T1D candidate genes were selected for this study and genotyped in duplicate on two platforms, Illumina and Sequenom. The genes were chosen based on published literature as having been either 'confirmed' (replicated) or not (candidates). This study showed several important features of genetic association studies. First, it showed the major impact of small rates of genotyping errors on association statistics. Second, it confirmed associations at INS, PTPN22, IL2RA, IFIH1 (earlier confirmed genes), and CTLA4 (earlier confirmed, with distinct SNPs) loci. Third, it did not find evidence for an association with T1D at SUMO4, despite confirmed association in Asian populations, suggesting the potential for population-specific gene effects. Fourth, at PTPN22, there was evidence for a novel contribution to T1D risk, independent of the replicated effect of the R620W variant. Fifth, among the candidate genes selected for replication, the association of TCF7-P19T with T1D was newly replicated in this study. In summary, this study was able to replicate some genetic effects, reject others, and provide suggestions of association with several of the other candidate genes in stratified analyses (age at onset, HLA status, population of origin). These results have generated additional interesting functional hypotheses that will require further replication in independent cohorts.

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.

Analysis of 19 genes for association with type I diabetes in the Type I Diabetes Genetics Consortium families

In recent years the pace of discovery of genetic associations with type I diabetes (T1D) has accelerated, with the total number of confirmed loci, including the major histocompatibility complex (MHC) region, reaching 43. However, much of the deciphering of the associations at these, and the established T1D loci, has yet to be performed in sufficient numbers of samples or with sufficient markers. Here, 257 single-nucleotide polymorphisms (SNPs) have been genotyped in 19 candidate genes (INS, PTPN22, IL2RA, CTLA4, IFIH1, SUMO4, VDR, PAX4, OAS1, IRS1, IL4, IL4R, IL13, IL12B, CEACAM21, CAPSL, Q7Z4c4(5Q), FOXP3, EFHB) in 2300 affected sib-pair families and tested for association with T1D as part of the Type I Diabetes Genetics Consortium's candidate gene study. The study had approximately 80% power at alpha=0.002 and a minor allele frequency of 0.2 to detect an effect with a relative risk (RR) of 1.20, which drops to just 40% power for a RR of 1.15. At the INS gene, rs689 (-23 HphI) was the most associated SNP (P=3.8 x 10(-31)), with the estimated RR=0.57 (95% confidence interval, 0.52-0.63). In addition, rs689 was associated with age-at-diagnosis of T1D (P=0.001), with homozygosity for the T1D protective T allele, delaying the onset of T1D by approximately 2 years in these families. At PTPN22, rs2476601 (R620W), in agreement with previous reports, was the most significantly associated SNP (P=6.9 x 10(-17)), with RR=1.55 (1.40-1.72). Evidence for association with T1D was observed for the IFIH1 SNP, rs1990760 (P=7.0 x 10(-4)), with RR=0.88 (0.82-0.95) and the CTLA4 SNP rs1427676 (P=0.0005), with RR=1.14 (1.06-1.23). In contrast, no convincing evidence of association was obtained for SUMO4, VDR, PAX4, OAS1, IRS1, IL4, IL4R, IL13, IL12B, CEACAM21 or CAPSL gene regions (http://www.T1DBase.org).

No Evidence of Association of CTLA-4 -318 C/T, 159 C/T, 3′ STR and SUMO4 163 AG Polymorphism with Autoimmune Diabetes

Autoimmune diabetes is an organ specific and multifactorial disorder including insulin dependent diabetes mellitus (Type 1 Diabetes) and latent autoimmune diabetes in adults (LADA), which progresses to insulin dependency because of the beta cells destruction. Several polymorphisms in different genes have been associated with diabetes. The CTLA4 gene is considered a down regulator of T cell function, and the SUMO4 gene encodes a small ubiquitin-like modifier implicated in the intensity and duration of the immune response. We selected 62 LADA patients, 123 patients with Type 1 diabetes patients and 136 unrelated volunteers to study CTLA4 -318 C/T, 159 C/T, 3' STR and SUMO4 163 A/G polymorphisms by PCR. There was a statistical difference significant in the frequency of the allele 209pb for the 3'STR between LADA and Type 1 diabetes patients but not with respect the normal group, the frequencies were found to be 6.9%, 1.0% and 1.9%, respectively. However, no association with either of the polymorphisms has been found in the studied population. The knowledge of the several susceptibility loci in autoimmune diabetes will enhanced the prediction of individuals at high risk of developing the disease in order to establish the best treatment and the prevention of autoimmune diabetes.

Polymorphisms in the ADRB2 gene and Graves disease: a case-control study and a meta-analysis of available evidence

Background

The beta-2-Adrenergic receptor (ADRB2) gene on chromosome 5q33.1 is an important immunoregulatory factor. We and others have previously implicated chromosomal region 5q31-33 for contribution to the genetic susceptibility to Graves disease (GD) in East-Asian populations. Two recent studies showed associations between the single nucleotide polymorphism (SNP) rs1042714 in the ADRB2 gene and GD. In this study, we aimed to fully investigate whether the ADRB2 gene conferred susceptibility to GD in Chinese population, and to perform a meta-analysis of association between ADRB2 and GD.

Methods

Approximately 1 kb upstream the transcription start site and the entire coding regions of the ADRB2 gene were resequenced in 48 Han Chinese individuals to determine the linkage disequilibrium (LD) patterns. Tag SNPs were selected and genotyped in a case-control collection of 1,118 South Han Chinese subjects, which included 428 GD patients and 690 control subjects. A meta-analysis was performed with the data obtained in the present samples and those available from prior studies.

Results

Fifteen SNPs in the ADRB2 gene were identified by resequencing and one SNP was novel. Ten tag SNPs were investigated further to assess association of ADRB2 in the case-control collection. Neither individual tag SNP nor haplotypes showed association with GD in Han Chinese population (P > 0.05). Our meta-analysis of the ADRB2 SNP rs1042714 measured heterogeneity between the ethnic groups (I² = 53.1%) and no association to GD was observed in the overall three studies with a random effects model (OR = 1.13, 95% CI, 0.95 to 1.36; P = 0.18). However, significant association was found from the combined data of Caucasian population with a fixed effects model (OR = 1.18, 95% CI, 1.06 to 1.32; P = 0.002; I² = 5.9%).

Conclusion

Our study indicated that the ADRB2 gene did not exert a substantial influence on GD susceptibility in Han Chinese population, but contributed to a detectable GD risk in Caucasian population. This inconsistency resulted largely from between-ethnicity heterogeneity.

Familial Graves' disease associated with type 1 diabetes

A 59-year-old woman was diagnosed as having Graves' disease and type 1 diabetes. DNA molecular HLA typing detected DRB1(*)0405 and DQB1(*)0401, as well as the haplotypes of DRB1(*)0901-DQB1(*)0303. We also performed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to identify allele variations of other loci. The patient's son also manifested Graves' disease and type 1 diabetes, with both cases having strikingly homologous clinical features. Familial clustering of Graves' disease and type 1 diabetes, and their tendency to occur together along with a similar clinical course suggest that their etiology may involve shared genetic factors.

Genetic Basis of Type 1 Diabetes: Similarities and Differences between East and West

Type 1 diabetes is a multifactorial disease caused by a complex interaction of genetic and environmental factors. The genetic factors involved consist of multiple susceptibility genes, at least five of which, HLA, INS, CTLA4, PTPN22 and IL2RA/CD25, have been shown to be associated with type 1 diabetes in Caucasian (Western) populations, as has recently been confirmed by genome-wide association studies. It has been proposed, however, that the contribution of these genes to type 1 diabetes susceptibility may be different in Asian (Eastern) populations. HLA and INS genes are consistently associated with type 1 diabetes in both Caucasian and Asian populations, but apparent differences in disease-associated alleles and haplotypes are observed between Japanese and Caucasian subjects. The association of CTLA4 with type 1 diabetes is concentrated in a subset of patients with autoimmune thyroid disease (AITD) in both Japanese and Caucasian populations, while the association of PTPN22 with type 1 diabetes in Japanese and most Asian populations is not as clear as in Caucasians. IL2RA/CD25 genes seem to be similarly distributed in type 1 diabetes patients in the two populations, whereas genetic heterogeneity may exist regarding SUMO4, with an association of the M55V variant with type 1 diabetes observed in Asians, but not in Caucasians. Genome-wide association studies (GWA) are largely outstanding for Asian populations but they are now underway in Japan. This review reports on the discovered similarities and differences in susceptibility genes for type 1 diabetes between East and West and discusses the most recent observations made by the involved investigators.

SUMO4 and its role in type 1 diabetes pathogenesis

Susceptibility to type 1 diabetes (T1D) is determined by interactions of multiple genes with unknown environmental factors. Despite the characterization of over 20 susceptibility regions for T1D, identification of specific genes in these regions is still a formidable challenge. In 2004, we first reported the cloning of a novel, small ubiquitin-like modifier (SUMO) gene, SUMO4, in the IDDM5 interval on chromosome 6q25, and presented strong genetic and functional evidence suggesting that SUMO4 is a T1D susceptibility gene. Subsequent studies have consistently confirmed this association in multiple Asian populations despite controversial observations in Caucasians. In this review, we will update the genetic evidence supporting SUMO4 as a T1D susceptibility gene and discuss the possible explanations for the discrepant associations observed in Caucasians. We will then discuss the mechanisms through which SUMO4 contributes to the pathogenesis of T1D.

Genetics of type 1 diabetes in Asian and Caucasian populations

Among candidate genes for type 1 diabetes, HLA, INS, CTLA4, PTPN22 and SUMO4 have been shown to be associated with the disease in Caucasian populations. To clarify the similarities and differences in the contribution of these genes to type 1 diabetes between Asian and Caucasian populations, association of these genes with type 1 diabetes was studied in a large number of samples in Japanese and Korean populations. Class II HLA was strongly associated with type 1 diabetes in both Asian and Caucasian populations, but haplotypes associated with type 1 diabetes were markedly different due to difference in the presence and absence of haplotypes in each population. INS was consistently associated with type 1 diabetes in both Japanese and Caucasian populations, but frequency of disease-associated haplotype was markedly high in Japanese general population. CTLA4 was associated with type 1 diabetes only in a subset of patients with type 1 diabetes complicated with AITD in Japanese. A variant (R620W) of PTPN22 was associated with type 1 diabetes and other autoimmune diseases in Caucasians, but the variant was absent in Asians. SUMO4 was associated with type 1 diabetes in Asians, but not in Caucasian, suggesting a genetic heterogeneity among diverse ethnic groups. Trans-racial study with a large number of samples in both Asian and Caucasian populations will contribute to genetic dissection of type 1 diabetes and identification of causative variants.

Functional evaluation of the type 1 diabetes (T1D) susceptibility candidate genes

Progress has been made in investigating the genetic factors involved in type 1 diabetes (T1D) development for the past few years. While Linkage disequilibrium (LD) mapping has been useful for both the confirmation and fine-mapping of susceptibility intervals, as well as identification of etiological mutations, identification of specific disease genes has been a challenge and limited to known candidate genes. The overall risk for T1D from the HLA DR and DQ molecules (IDDM1) is determined by combinations of polymorphic alleles. Functional studies indicate that the susceptible and protective HLA-DR and -DQ bind and present non-overlapping peptides. Although consistent linkage evidence was reported for the susceptibility intervals IDDM2, IDDM5 and IDDM12, evidence for most other intervals varies in different data sets. The variable number of tandem repeats at the 5' end of the insulin gene (IDDM2) regulates insulin expression in the thymus. Studies on IDDM5 have led to the discovery of a novel polymorphism 163 A-->G (M55V) in SUMO4 gene, which was found to be associated with T1D patients with Asian origin. Functionally SUMO4 conjugates to IkBalpha and negatively regulates NFkB transcriptional pathway. The M55V substitution reduces the sumoylation activity of the V55 variant, which resulted in higher NFkB dependent transcriptional activity. The polymorphisms of the cytotoxic T lymphocyte antigen 4 gene (CTLA4, IDDM12) encoding a regulatory molecule in the immune system associate with T1D and autoimmune thyroid diseases (ATD). The 3' untranslated region of this gene determines the level of soluble CTLA-4. Genetic mapping of variants conferring a small disease risk can identify pathways in complex disorders, as evidenced by quantitative alterations of candidate genes contributing to autoimmune tissue destruction. Moreover, the identification of two transcription factors that, when mutated, are responsible for severe autoimmune disease is leading to a better understanding of T cell tolerance. Both AIRE and Foxp3, identified initially via their association with genetically manipulated mice, are involved in tolerance induction in humans. Although mutations in these genes may cause rare but serious diseases, it is likely that other transcription factors will contribute to the genetic load that predisposes certain individuals to disease.

No association of SUMO4 M55V with autoimmune diabetes in Asian-Indian patients

Autoimmune diabetes [type 1 diabetes mellitus (T1DM), latent autoimmune diabetes in adults (LADA) and part of malnutrition-related diabetes] has been shown to have genetic predisposition. Studies in IDDM 5 have lead to the discovery of a novel polymorphism 163 A-->G, of SUMO4 (small ubiquitin-related modifier) gene, associated with risk to T1DM in Asians, but not in Caucasians. We studied patients with T1DM (n = 134), patients with LADA (n = 101), patients with malnutrition-modulated diabetes mellitus (n = 66) and patients with fibrocalculous pancreatic diabetes (n = 43) and healthy controls subjects (n = 114) from Cuttack, India. Polymerase chain reaction-sequence-specific primer (PCR-SSP) was used to amplify the 163 A-->G sequences. Restriction fragment length polymorphism (RFLP) was performed using restriction enzyme Taq I (PCR-RFLP). Differences in the allelic frequencies of the A and the G alleles were tested statistically using Fisher's exact test or chi-squared test wherever appropriate. P-values were considered significant when equal to or less than 0.05. No significant association was detected between SUMO4 M55V and T1DM susceptibility in Asian-Indians. Comparison of the A and G alleles with HLA DR3-DR4 did not result in any significant P-values. No significant association was found between SUMO4 M55V and LADA or malnutrition-related diabetes mellitus (MRDM). Our results show that Asian-Indians with T1DM are different from other Asian populations. Asian-Indians show more similarity to Caucasians with respect to the association of SUMO4 M55V variant in T1DM. Association studies on Asian-Indian patients with LADA and MRDM showed no significant difference in the presence of the A and the G alleles when compared to healthy controls.

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.

Association of small ubiquitin-like modifier 4 (SUMO4) variant, located in IDDM5 locus, with type 2 diabetes in the Japanese population

CONTEXT

Despite distinct differences in the pathogenesis, epidemiological data have indicated familial clustering of type 1 and type 2 diabetes, suggesting a common genetic basis between these two types of diabetes. Few shared susceptibility genes, however, have been reported to date.

OBJECTIVE

Small ubiquitin-like modifier 4 (SUMO4) has been identified as a candidate gene for the IDDM5 locus and suggested to have possible involvement in immune responses, such as autoimmunity and inflammation. Recent reports demonstrated that a polymorphism with an amino acid substitution (Met55Val) in SUMO4 was associated with type 1 diabetes in Asian populations, although no association was reproduced in subjects of Caucasian descent. The present study aimed to clarify the contribution of SUMO4 to type 2 diabetes susceptibility in the Japanese population.

SUBJECTS

The 753 subjects included 355 cases and 398 control subjects.

METHODS

The SUMO4 Met55Val (rs237025) and 001Msp (rs577001) polymorphisms were genotyped.

RESULTS

Strong linkage disequilibrium (D': 1.0 in each pair of single-nucleotide polymorphisms) across the MAP3K7IP2/SUMO4 region was shown in the Japanese population. The frequency of genotypes with the G allele of the SUMO4 Met55Val polymorphism was significantly higher in patients with type 2 diabetes [odds ratio, 1.46; 95% confidence interval (CI), 1.08-1.93; P = 0.01, chi(2) test]. The association was concentrated in patients without insulin therapy (odds ratio, 1.56; 95% CI, 1.13-2.15; P = 0.0072), but not in those with insulin (odds ratio, 1.24; 95% CI, 0.81-1.89; not significant).

CONCLUSIONS

These data, together with previous reports, suggest the contribution of the SUMO4 Met55Val polymorphism to both type 1 and type 2 diabetes susceptibility in the Japanese population.

SUMO4 M55V variant is associated with diabetic nephropathy in type 2 diabetes

OBJECTIVE-SUMO4 mRNA was recently found to be mainly expressed in the kidney, and the methionine-to-valine substitution at codon 55 (M55V) variant of SUMO4 may induce higher nuclear factor-kappaB (NF-kappaB) activity. Because NF-kappaB is known to mediate the development of diabetic nephropathy, we examined the association between the SUMO4 M55V variant and the severity of diabetic nephropathy. RESEARCH DESIGN AND METHODS-We recruited a total of 430 patients with type 2 diabetes. The M55V (rs237025, 163A-->G) polymorphism of SUMO4 was genotyped by real-time PCR, and urine albumin concentration was measured by radioimmunoassay. RESULTS-The frequencies of SUMO4 AA, GA, and GG were 52.6, 40.7, and 6.7%, respectively, in the normoalbuminuric group; 45.5, 47.3, and 7.1% in the microalbuminuric group; and 36.9, 46.2, and 16.9% in the macroalbuminuric group. We detected a significant linear trend for SUMO4 genotype between the macroalbuminuric and normoalbuminuric groups. The mean urine albumin-to-creatinine ratio (42.3 +/- 108.82 mg/mmol) in the GG group was significantly higher than in the AA (14.9 +/- 51.49 mg/mmol) and GA (17.0 +/- 43.74 mg/mmol) groups. Multivariate logistic regression analysis showed the SUMO4 M55V variant to be independently associated with the severity of diabetic nephropathy. CONCLUSIONS-This study indicates that the SUMO4 gene M55V variant is associated with severity of diabetic nephropathy in patients with type 2 diabetes.

Association of SUMO4 M55V polymorphism with autoimmune diabetes in Latvian patients

Small ubiquitin-related modifier (SUMO4), located in IDDM5, has been identified as a potential susceptibility gene for type 1 diabetes mellitus (T1DM). The novel polymorphism M55V, causing an amino acid change in the evolutionarily conserved met55 residue has been shown to activate the nuclear factor kappaB (NF-kappaB), hence the suspected role of SUMO4 in the pathogenicity of T1DM. The M55V polymorphism has been shown to be associated with susceptibility to T1DM in Asians, but not in Caucasians. Latent autoimmune diabetes in adults (LADA) is a slowly progressive form of T1DM and SUMO4 M55V has not been studied in LADA to date. The current study aims to test whether Latvians are similar to Caucasians in susceptibility to autoimmune diabetes (T1DM and LADA), with respect to SUMO4 M55V. We studied, age- and sex-matched, Latvian T1DM patients (n = 100) and healthy controls (n = 90) and LADA patients (n = 45) and healthy controls (n = 95). SUMO4 M55V polymorphism was analyzed using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). The allelic frequencies of the A and G alleles were compared with HLA DR3-DR4-positive and HLA DR3-DR4-negative patients to identify any potential relation between HLA DR3-DR4 and SUMO4 M55V. We found no significant association between SUMO4 M55V and T1DM susceptibility in Latvians, the results being in concurrence with the previous studies in Caucasians of British and Canadian origin. Comparison of the A and G alleles with HLA DR3-DR4 did not result in any significant P values. No significant association was found between SUMO4 M55V and LADA. SUMO4 M55V is not associated with susceptibility to T1DM and LADA in Latvians, and Latvians exhibit similarity to other Caucasians with respect to association of SUMO4 M55V with autoimmune diabetes.

Genetic and functional evidence supporting SUMO4 as a type 1 diabetes susceptibility gene

Genomewide linkage analyses since the early 1990s suggested over 20 genomic intervals that may contain susceptibility genes for type 1 diabetes. However, the identification of the specific genes in these intervals presents a formidable challenge due to a number of difficulties associated with genetic mapping and cloning of genes implicated in complex diseases. One of the difficulties is due to the presence of many weak and different susceptibility genes in different patients and populations, a phenomenon known as genetic heterogeneity. In 2004, we reported the cloning of a novel small ubiquitin-like modifier (SUMO) gene, SUMO4, in the IDDM5 interval on chromosome 6q25, and presented strong genetic and functional evidence suggesting that SUMO4 is a susceptibility gene for type 1 diabetes mellitus (T1DM). In this article, we will summarize genetic association data suggesting that SUMO4 is consistently associated with T1DM in the Asian populations while the association is more heterogeneous in the Caucasian populations. We will also discuss the possible molecular pathways through which sumoylation may regulate T1DM and autoimmunity.

Why is type 1 diabetes uncommon in Asia?

T1D (type 1 diabetes) incidence rates are extremely low in Asian populations. The prevalences of islet-specific autoantibodies are reported to be low compared with Caucasians. Although the clinical and immunologic characteristics of T1D in Asians appear to be different from those of Caucasians, if we apply correct patient definition and standardized methods, the typical T1D patients are very similar, in the immunologic as well as genetic perspectives. Although the association of individual allele seems to be different between populations, if we compare the identical DR-DQ haplotypes, the association and transmission to diabetic offspring were similar for Asians and Caucasians. The high-risk HLA genotypes/haplotypes were found to be independent determinants of diabetes in the first-degree relatives of individuals with T1D, particularly in the presence of autoantibodies. A different genetic susceptibility including a low frequency of high-risk HLA alleles could explain the lower prevalence of islet-specific autoantibodies and the low incidence of T1D, or different genetic and environmental interactions might be involved in the etiology of T1D. It is certain that DR-DQ linkage disequilibrium (LD) is an important factor explaining the difference in T1D incidence in different countries. LD between highly susceptible DRB1 alleles and protective DQB1 alleles, and vice versa, is the major contributing factor to the low incidence of T1D in Asians. We also suggested that different genetic/environmental interactions might operate in the etiology of T1D between Caucasians and Asians. It would be of great help for primary prevention to investigate to what degree genetic determinants influence the well-known regional differences in incidences, since we can identify environmental risk factors that may either initiate the autoimmune process or promote already ongoing beta cell damage in different countries. For this, population-based epidemiological studies are necessary to identify risk determinants that may be useful for primary prevention strategies.

Association of SUMO4, as a Candidate Gene for IDDM5, with Susceptibility to Type 1 Diabetes in Asian Populations

Recent study demonstrated that M55V variant in SUMO4 at IDDM5 was associated with susceptibility to type 1 diabetes. Subsequent studies, however, showed inconsistency in the association. To clarify the population-wide effect on the association of SUMO4 with type 1 diabetes, we have performed meta-analysis including our own data in Asian populations, which confirmed a highly significant association in Asian populations (summary odds ratio [OR]: 1.29, P = 7.0 x 10(-6)), but indicated significant heterogeneity in the genetic effect of the SUMO4 gene on type 1 diabetes among diverse ethnic groups. These observations indicated the association of SUMO4 with type 1 diabetes in Asian populations.

Genetics of Type 1 Diabetes: Similarities and Differences between Asian and Caucasian Populations

Transracial studies are a powerful tool for genetic association studies of multifactorial diseases, such as type 1 diabetes. We therefore studied the association of candidate genes, HLA, INS, CTLA4, PTPN22, and SUMO4, with type 1 diabetes in Asian populations in comparison with Caucasian populations. Class II HLA was strongly associated with type 1 diabetes in both Asian and Caucasian populations, but alleles associated with type 1 diabetes are different among different ethnic groups due to difference in allele distribution in general populations. INS was associated with type 1 diabetes in both Japanese and Caucasian populations, but frequency of disease-associated haplotype was markedly higher in Japanese than in Caucasian populations. CTLA4 association was reported for both type 1 diabetes and autoimmune thyroid diseases (AITD) in Caucasian populations, but the association with type 1 diabetes was concentrated in a subset of patients with AITD in Japanese. A variant (R620W) of PTPN22 was consistently associated with type 1 diabetes in Caucasian populations, but the variant was absent in Asian populations including Japanese. M55V variant of SUMO4 was significantly associated with type 1 diabetes in Asians, but genetic heterogeneity between Asian and Caucasian populations was suggested. These data indicate the importance of transracial studies with a large number of samples in each ethnic group in genetic dissection of type 1 diabetes.

Genes mediating environment interactions in type 1 diabetes

The relative risk of type 1 (autoimmune) diabetes mellitus for a sibling of an affected patient is fifteen times that of the general population, indicating a strong genetic contribution to the disease. Yet, the incidence of diabetes in most Western communities has doubled every fifteen years since the Second World War - a rate of increase that can only possibly be explained by a major etiological effect of environment. Here, the authors provide a selective review of risk factors identified to date. Recent reports of linkage of type 1 diabetes to genes encoding pathogen pattern recognition molecules, such as toll-like receptors, are discussed, providing a testable hypothesis regarding a mechanism by which genetic and environmental influences on disease progress are integrated.

Proteomic analysis of SUMO4 substrates in HEK293 cells under serum starvation-induced stress

The substrates of SUMO4, a novel member for the SUMO gene family, were characterized in HEK293 cells cultured under serum starvation by proteomic analysis. We identified 90 SUMO4 substrates including anti-stress proteins such as antioxidant enzymes and molecular chaperones or co-chaperones. The substrates also include proteins involved in the regulation of DNA repair and synthesis, RNA processing, protein degradation, and glucose metabolism. Several SUMO4-associated transcription factors were characterized by Western blot analyses. AP-1 was selected for in vitro conjugation assays to confirm SUMO4 sumoylation of these transcription factors. Further functional analyses of the transcription factors suggested that SUMO4 sumoylation represses AP-1 and AP-2alpha transcriptional activity, but enhances GR DNA binding capacity. These results demonstrate that SUMO4 sumoylation may play an important role in the regulation of intracellular stress.