The complete exon-intron structure of the 156-kb human gene NFKB1, which encodes the p105 and p50 proteins of transcription factors NF-kappa B and I kappa B-gamma: implications for NF-kappa B-mediated signal transduction

Cellular senescence marker p16INK4a and NFKB1 gene polymorphisms in lower gastro-intestinal acute graft versus host disease

BACKGROUND

Lower gastrointestinal (GI) graft versus host disease (GVHD) represents a severe complication in allogeneic hematopoietic stem cell transplant (HSCT) recipients with high rates of transplant-related mortality. Deregulated innate immunity reactions are the features of its pathogenesis. Cellular senescence has been considered a program of the innate immunity. We focused on lower GI GVHD from the perspective of cellular senescence.

OBJECTIVE

We analyzed the impact of p16^INK4a expression, a hallmark of cellular senescence, in intestinal biopsies of patients with lower GI GVHD symptoms and NFKB1 gene polymorphisms (rs3774937 C/T and rs3774959 A/G) on HSCT outcome.

STUDY DESIGN

Fifty-two single-center patients who presented with symptoms of lower GI GVHD were analyzed in a retrospective manner. Two SNPs located in the NFKB1 gene regions (rs3774937 C/T and rs3774959 A/G) were genotyped from the peripheral blood samples collected before the start of the conditioning. All patients underwent proctosigmoidoscopy with biopsy of the mucosa. The expression of p16^INK4a was analyzed in normal intestinal crypts and stroma.

RESULTS

Fifty-two patients (50% male) received HSCT for hematological diseases (acute leukemias in 67%) and developed lower GI symptoms. Patients with p16^INK4a expression in the intestinal stroma were in lower risk of developing histological grade 3-4 aGVHD (RR 0.18 [95% CI 0.05-0.65]; p = 0.009). The multivariate linear regression confirmed the independent effect of p16^INK4a expression on time of the lower GI aGVHD symptoms onset (Coef. 38.9 [95% CI 12.7-65.1]; p = 0.005). The NFKB1 rs3774937 CC and TT/TC genotype were present in 40 and 80% of patients with p16^INK4a expression, respectively (p = 0.04). The rs3774959 AA and GG/AG genotype were present among 43 and 82% of patients with p16^INK4a expression, respectively (p = 0.02). Expression of p16^INK4a was associated with no clinical variable but NFKB1 genotype.

CONCLUSIONS

Our results address possible new mechanisms that may lead to better understanding of HSCT-related immune complications. Cellular senescence may bring novel approaches in GVHD diagnostics and therapy.

The significant role of a functional polymorphism in the NF-κB1 gene in breast cancer: evidence from an Iranian cohort

Aims: Breast cancer (BC) is one of the most common cancers among women. The influence of genetic variations on BC risk has been thus far assessed via genome-wide association studies. NF-κB has been recognized as a major player in BC progression. In this study, the association between rs28362491 and BC was evaluated in a population from northeastern Iran. Materials & methods: This study was conducted on 476 patients with BC and 524 healthy controls. The genotyping method used was an amplification-refractory mutation system. Results: The INS/DEL genotype conferred a statistically significant increased risk in patients in comparison with controls. Additionally, in the recessive model, INS/INS + INS/DEL versus DEL/DEL was statistically significant (OR = 0.34; 95% CI: 0.12-0.96; p = 0.042). Conclusion: This study found that rs28362491, as a susceptibility genetic factor, may affect BC risk in the Iranian population.

S100 Calcium-Binding Protein P Secreted from Megakaryocytes Promotes Osteoclast Maturation

Megakaryocytes (MKs) differentiate from hematopoietic stem cells and produce platelets at the final stage of differentiation. MKs directly interact with bone cells during bone remodeling. However, whether MKs are involved in regulating bone metabolism through indirect regulatory effects on bone cells is unclear. Here, we observed increased osteoclast differentiation of bone marrow-derived macrophages (BMMs) cultured in MK-cultured conditioned medium (MK CM), suggesting that this medium contains factors secreted from MKs that affect osteoclastogenesis. To identify the MK-secreted factor, DNA microarray analysis of the human leukemia cell line K562 and MKs was performed, and S100 calcium-binding protein P (S100P) was selected as a candidate gene affecting osteoclast differentiation. S100P was more highly expressed in MKs than in K562 cells, and showed higher levels in MK CM than in K562-cultured conditioned medium. In BMMs cultured in the presence of recombinant human S100P protein, osteoclast differentiation was promoted and marker gene expression was increased. The resorption area was significantly larger in S100P protein-treated osteoclasts, demonstrating enhanced resorption activity. Overall, S100P secreted from MKs promotes osteoclast differentiation and resorption activity, suggesting that MKs indirectly regulate osteoclast differentiation and activity through the paracrine action of S100P.

Combined immunodeficiency caused by a novel homozygous NFKB1 mutation

BACKGROUND

Genetic faults in several components of the nuclear factor-κB pathway cause immunodeficiency. Most defects lead to combined immunodeficiency with a range of severity. Heterozygous mutations in NFKB1 were associated with common variable immunodeficiency, however, homozygous mutations have not been described.

OBJECTIVE

We studied the molecular basis of combined immunodeficiency in a patient who presented with failure to thrive, persistent EBV viremia and hepatitis, pneumocystis jirovecii pneumonitis, and generalized lymphadenopathy.

METHODS

Whole genome and exome sequencing followed by Sanger confirmation were performed to identify the genetic defect. Molecular and cellular techniques were used to assess the variant impact on the nuclear factor-κB pathway and lymphocyte function.

RESULTS

Genetic analysis revealed a novel homozygous mutation in NFKB1, c.2878G>A, p.Gly960Arg (G960R). This affected p105 phosphorylation and p50 formation on antigen and cytokine stimulation, as well as attenuating nuclear signal transmission. As a result, both T- and B-cell maturation and function were perturbed. The number of memory CD4⁺ T cells were reduced, while CD8⁺ T cells consisted predominately of expanded differentiated populations. The function of T cells were diminished as shown by reduced responses to mitogens as well as diminished cytokine secretion. B-cell maturation was also affected, with decreased IgD⁺CD27⁺ memory B cells while transitional B cells were increased, likely contributing to the reduced ability to produce specific antibodies.

CONCLUSION

Homozygous G960R mutation in NFKB1 leads to a severe clinical presentation of combined immunodeficiency. This was associated with blockade of nuclear factor-κB pathway signaling, resulting in aberrations in T- and B-cell maturation and function.

Functional variations of NFKB1 and NFKB1A in inflammatory disorders and their implication for therapeutic approaches

Nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) is a sophisticated transcription factor that is particularly important in the inflammatory response, but it regulates more than 400 individual and dependent genes for parts of the apoptotic, angiogenic, and proliferative, differentiative, and cell adhesion pathways. NF-κB function is directly inhibited by the binding of inhibitor of κB (IκB), and the imbalance between NF-κB and IκB has been linked to the development and progression of cancer and a variety of inflammatory disorders. These observations might broaden the horizon of current knowledge, particularly on the pathogenesis of inflammatory diseases considering the roles of NF-κB and IκB. In this context, we focus this narrative review on a comparative discussion of our findings with other literature regarding variations of NFKB1 and NFKB1A and their association with susceptibility to widespread inflammatory disorders (such as atherosclerosis, morbid obesity, Behçet syndrome, Graves disease, Hashimoto disease) and common cancers (such as gliomas).

Significant association between rs28362491 polymorphism in NF-κB1 gene and coronary artery disease: a meta-analysis

BACKGROUND

The association of rs28362491 polymorphism in NF-κB1 gene and coronary artery disease (CAD) risk was reported in several studies with inconsistent outcomes. This study aimed to comprehensively collect and synthesize the existing evidence to appraise whether rs28362491 was correlated to CAD susceptibility.

METHODS

Databases of Web of Science, EMBASE, PubMed, Wanfang, and CNKI were retrieved from inception to August 1, 2019 without any restriction on language. The strengths of association between rs28362491 polymorphism and CAD were presented as odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Thirteen case-control studies with 17 individual cohorts containing 9378 cases and 10,738 controls were incorporated into this meta-analysis. The findings indicated that rs28362491 polymorphism was significantly correlated to CAD risk in five genetic models: D vs. I, OR = 1.16, 95%CI 1.11-1.21, P<0.01; DD vs. II, OR = 1.37, 95%CI 1.25-1.49, P<0.01; DI vs. II, OR = 1.11, 95%CI 1.05-1.18, P<0.01; DD + DI vs. II, OR = 1.17, 95%CI 1.11-1.24, P<0.01; DD vs. DI + II, OR = 1.29, 95%CI 1.15-1.43, P<0.01. After stratification by ethnicity and gender, significant association still existed between rs28362491 and CAD, especially in the dominant model.

CONCLUSIONS

The findings suggest that the mutant D allele in rs28362491 locus may increase the risk of CAD, and carriers of D allele appear to be more susceptible to CAD.

NFKB1 gene single-nucleotide polymorphisms: implications for graft-versus-host disease in allogeneic hematopoietic stem cell transplantation

Graft-versus-host disease (GVHD) represents a significant cause of mortality after allogeneic hematopoietic stem cell transplantation (HSCT). NF-kB system is a master regulator of innate immunity responses. It controls the expression of various cytokines and chemokines many of which are involved in GVHD pathogenesis. Chemo(radio) therapy administered during conditioning induces DNA damage and activates DNA damage response (DDR) signaling resulting in irreversible cell cycle arrest - cellular senescence which has been described to be associated with robust pro-inflammatory secretion mostly controlled by NF-kB. The NFKB1 gene encodes the DNA-binding subunit of the NF-kB complex. Using the candidate gene approach, we analyzed possible association of two single-nucleotide polymorphisms (SNPs) rs3774937 C/T and rs3774959 A/G of the NFKB1 gene with GVHD and transplant-related mortality (TRM) occurrence in 109 recipients allografted from HLA-identical donor. Both SNPs in recipients were found to be strongly associated with acute GVHD. Nevertheless, no significant association with chronic GVHD and TRM was found. Presented pilot results contribute to pre-clinical observations and suggest that NF-kB may be an important regulator of HSCT-related inflammatory reactions such as acute GVHD. Novel pathogenic mechanisms of GVHD may arise from perspectives of DDR and cellular senescence where NF-kB plays an essential role.

Molecular mechanisms linking peri-implantitis and type 2 diabetes mellitus revealed by transcriptomic analysis

Aims

To explore molecular mechanisms that link peri-implantitis and type 2 diabetes mellitus (T2DM) by bioinformatic analysis of publicly available experimental transcriptomic data.

Materials and methods

Gene expression data from peri-implantitis were downloaded from the Gene Expression Omnibus database, integrated and differentially expressed genes (DEGs) in peri-implantitis were identified. Next, experimentally validated and computationally predicted genes related to T2DM were downloaded from the DisGeNET database. Protein–protein interaction network (PPI) pairs of DEGs related to peri-implantitis and T2DM related genes were constructed, “hub” genes and overlapping DEG were determined. Functional enrichment analysis was used to identify significant shared biological processes and signaling pathways. The PPI networks were subjected to cluster and specific class analysis for identifying “leader” genes. Module network analysis of the merged PPI network identified common or cross-talk genes connecting the two networks.

Results

A total of 92 DEGs overlapped between peri-implantitis and T2DM datasets. Three hub genes (IL-6, NFKB1, and PIK3CG) had the highest degree in PPI networks of both peri-implantitis and T2DM. Three leader genes (PSMD10, SOS1, WASF3), eight cross-talk genes (PSMD10, PSMD6, EIF2S1, GSTP1, DNAJC3, SEC61A1, MAPT, and NME1), and one signaling pathway (IL-17 signaling) emerged as peri-implantitis and T2DM linkage mechanisms.

Conclusions

Exploration of available transcriptomic datasets revealed IL-6, NFKB1, and PIK3CG expression along with the IL-17 signaling pathway as top candidate molecular linkage mechanisms between peri-implantitis and T2DM.

The association between NFKB1 -94ATTG ins/del and NFKB1A 826C/T genetic variations and coronary artery disease risk

Coronary artery disease (CAD) is considered as a chronic inflammatory disease initiated from early childhood. Nuclear factor κB (NF κB) and κB1A (NF κB1A) are the key regulators of inflammatory responses. The NFKB1 -94ATTG ins/del and NFKB1A -826C/T polymorphisms may contribute to the development of CAD. The aim of the present study was to investigate the association of these polymorphisms with the risk of CAD. The study population included 120 patients with angiographically confirmed CAD and 100 matched controls. Genotyping of NFKB1 -94ATTG ins/del and NFKB1A -826C/T polymorphism was performed using PCR-RFLP method. Lipid level was determined by routine colorimetric methods. Statistical analysis was done by SPSS 16 software. Results indicated that the genotypic (P=0.041) and allelic (P=0.009) distribution of the NFKB1-94ATTG ins/del polymorphism was significantly different between the two groups. In the univariate analysis (ins/ins genotype as reference), the del/del genotype (OR=2.88, 95% CI=1.21-6.84, P=0.015) but not ins/del genotype (OR=1.48, 95% CI=0.83-2.64, P=0.191) was significantly associated with the increased risk of CAD. In the multiple binary logistic regression analysis, diabetes, hypertension, smoking, LDL-cholesterol, total cholesterol, HDL-cholesterol and NFKB1 -94ATTG del/del genotype were identified as significant and independent risk factors for CAD development. The distribution of genotypes and alleles of NFKB1A -826C/T polymorphism was not significantly different between the two groups. In conclusion the present study identified NFKB1 -94ATTG ins/del polymorphism but not NFKB1A -826C/T polymorphism as a significant and independent risk factor for development and severity of CAD.

NFKB1 -94insertion/deletion ATTG polymorphism and cancer risk: Evidence from 50 case-control studies

Nuclear factor-kappa B1 (NF-κB1) is a pleiotropic transcription factor and key contributor to tumorigenesis in many types of cancer. Numerous studies have addressed the association of a functional insertion (I)/deletion (D) polymorphism (-94ins/delATTG, rs28362491) in the promoter region of NFKB1 gene with the risk of various types of cancer; however, their conclusions have been inconsistent. We therefore conducted a meta-analysis to reevaluate this association. PubMed, EMBASE, China National Knowledge infrastructure (CNKI), and WANFANG databases were searched through July 2016 to retrieve relevant studies. After careful assessment, 50 case-control studies, comprising 18,299 cases and 23,484 controls were selected. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were used to determine the strength of the association. The NFKB1 -94ins/delATTG polymorphism was associated with a decreased risk of overall cancer in the homozygote model (DD vs. II): OR = 0.75, 95% CI = 0.64-0.87); heterozygote model (ID vs. II): OR = 0.91, 95% CI = 0.83-0.99; recessive model (DD vs. ID/II): OR = 0.81, 95% CI = 0.71-0.91; dominant model (ID/DD vs. II): OR = 0.86, 95% CI = 0.78-0.95; and allele contrast model (D vs. I): OR = 0.88, 95% CI = 0.81-0.95). Subgroup and stratified analyses revealed decreased risks for lung cancer, nasopharyngeal carcinoma, prostate cancer, ovarian cancer, and oral squamous cell carcinoma, and this association held true also for Asians (especially Chinese subjects) in hospital-based studies, and in studies with quality scores less than nine. Well-designed, large-scale case-control studies are needed to confirm these results.

Association between NF-κBI and NF-κBIA polymorphisms and coronary artery disease

Coronary artery disease (CAD) is the leading cause of fatalities worldwide. Nuclear factor (NF)-κB is a transcription factor that controls cell proliferation, differentiation and immunity. To the best of our knowledge, the present study is the first investigation of the association between CAD and NF-κB1 -94 W/D/NF-κBIA 3'-untranslated region (3'-UTR) A→G polymorphisms. The study population comprised 226 CAD patients and 201 controls. There was no significant difference in NF-κB1A 3'-UTR A→G in the allele and genotype frequencies between case and control populations. The D allele frequency of NF-κB1 -94 in the case group was significantly higher compared to the control group (P=0.028, odds ratio=1.37). The genotype frequency of NF-κB1 -94 DD in the case group was significantly higher compared to the controls (P=0.028). Linkage analysis showed a close linkage among these 2 genes (P<0.001 for case and control), and AD and GD haplotypes were associated with CAD (P<0.001; P=0.015, respectively). NF-κB1 -94 DD genotype can be a significant risk factor for the development of CAD.

-94 ATTG insertion/deletion polymorphism of the NFKB1 gene is associated with coronary artery disease in Han and Uygur women in China

OBJECTIVES

The nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) signaling pathway plays a key role in the regulatory network of inflammation. The deletion variant allele of the NFKB1-94 insertion/deletion (ins/del) ATTG promoter polymorphism results in lower transcription levels of the p50 subunit, and the variant allele has been associated with several inflammatory diseases as well as with coronary artery disease (CAD) with inflammation playing an important part in the pathogenesis. The aim of the present study was to assess the association between the human NFKB1 gene polymorphism and CAD in a Han and Uygur population of China.

METHODS

We used the following two independent case-control studies: a Han population (633 CAD patients and 616 control subjects) and a Uygur population (437 CAD patients and 356 control subjects). All participants were genotyped for the same one single nucleotide polymorphism (SNP) (rs28362491) of the NFKB1 gene, that is, DD, ATTG deleted homozygote; ID, ATTG inserted and deleted heterozygote and II, ATTG inserted homozygote by real-time polymerase chain reaction.

RESULTS

The distribution of the SNP (rs28362491) genotypes was significantly different between CAD and control participants in women of the Han (p=0.029) and the Uygur (p=0.032) populations, but not in men. Further, DD carriers of the SNP in the NFKB1 gene were more frequent in female CAD patients than in controls in both the Han (23.2% vs. 13.5%, p=0.009) and the Uygur (19.8% vs. 8.3%, p=0.012) population. The significant difference between DD and ID+II genotypes was retained after adjustment for covariates (for Han, odds ratio [OR]: 1.805, p=0.029 and for Uygur, OR: 3.192, p=0.011).

CONCLUSIONS

The DD genotype of the SNP (rs28362491) in the NFKB1 gene may be considered a genetic marker of CAD in Han and Uygur women in China.

The joint association of REST and NFKB1 polymorphisms on the risk of colorectal cancer

Due to the high morbidity and mortality of colorectal cancer (CRC), this study aims to determine the joint association of RE-1-silencing transcription factor (REST) and nuclear factor-κB 1 (NFKB1) genes with CRC in a population-based study. A well-matched case-control study including 390 controls and 388 patients with CRC was enrolled in China. The selected single nucleotide polymorphisms (SNPs) in the REST and NFKB1 genes were genotyped by Illumina SnapShot Chip. After adjustment for important covariates, the associations of SNPs and joint association of REST and NFKB1 with CRC were evaluated by multiple logistic regression models. The subjects with the rs2228991 AA genotype of the REST gene had a decreased risk for CRC (OR = 0.38; 95%CI: 0.19-0.74), compared with the GG genotype. There were no significant associations between three SNPs in the NFKB1 gene, their haplotype and CRC risk. However, a significant combined effect of rs3774959 and rs3774964 in the NFKB1 gene with rs2228991 in the REST gene on CRC risk was observed. In conclusion, the present study found that mutation in the REST gene rather than the NFKB1 gene was associated with the risk of CRC. Furthermore, significant REST-NFKB1 joint association was observed for CRC, colon cancer and rectal cancer risk.

-94 ins/del ATTG NFKB1 gene variant is associated with lower susceptibility to myocardial infarction

BACKGROUND AND AIMS

An imbalance of Nuclear Factor Kappa B (NFкB) and Inhibitor Kappa B (IкB) is involved in various human diseases including atherogenesis. We aimed to evaluate the relationship between NFKB1 and NFKBIA polymorphism and susceptibility to myocardial infarction (MI).

METHODS AND RESULTS

Genotyping was performed for NFKB1 and NFKBIA gene variants in 253 subjects (86 patients affected by myocardial infarction and 167 control subjects). In 40 patients, biopsy specimens were taken from the left ventricle area of presumed ischemia for p50, p65 and IкBα quantification. The allele frequency and genotype distribution of NFKBIA gene polymorphism did not differ between MI and control group while control subjects had a higher D allele frequency of -94 ins/del ATTG NFKB1 polymorphism, compared to the MI group (P<0.001; OR=0.304; 95% CI=0.177-0.522). Subjects carrying the D allele had significantly lower plasma fibrinogen and CRP (C-reactive protein) levels compared to no carriers (P<0.05). Fibrinogen-genotype interaction was found to have a significant effect on susceptibility to myocardial infarction. Myocardial p50 (r=0.627; P=0.012) and p65 (r=0.683; P=0.005) levels significantly correlated with plasma fibrinogen levels while subjects carrying the D allele of the NFкB1 gene variant had lower myocardial p50 (P=0.007) and p65 (P=0.009) levels compared to no carriers.

CONCLUSION

-94 ins/del ATTG NFKB1 gene variant may contribute to lower MI susceptibility via the potential reduction of activated NFкB which in turn is related to plasma inflammatory marker reduction.

NFκB1 and NFκBIA polymorphisms are associated with increased risk for sporadic colorectal cancer in a southern Chinese population

BACKGROUND

Nuclear factor κB (NFκB) plays a key role in the regulation of apoptosis. The function of NFκB is inhibited by binding to NFκB inhibitor (IκB), and disruption of the balance of NFκB and IκB is related to the development of many diseases, including tumors. Therefore, we hypothesized that the NFκB1 (-94del/insATTG) and NFκBIA (2758 A>G) polymorphisms were associated with colorectal cancer (CRC) susceptibility.

METHODS

In a hospital-based case-control study of 1001 CRC patients and 1005 cancer-free controls frequency matched by age and sex, we genotyped polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and performed luciferase assays and Western blotting analysis to identify whether genetic variants in NFκBIA alter its gene expressions and functions and thus cancer risk.

RESULTS

We found that both NFκB1-94 ins/delATTG and NFκBIA 2758 A>G polymorphisms were correlated with CRC risk (OR = 1.47; 95%CI = 1.14-1.86, and OR = 1.38; 95% CI = 1.14-1.66, respectively). Furthermore, when evaluated these two polymorphisms together, the combined genotypes with 2 variant (risk) alleles (2758GG and -94ins/ins+del/ins) were associated with an increased risk of CRC (OR = 1.71; 95% CI = 1.23-2.38) compared to 0 variant, and the significant trend for 2 variant (risk) alleles were more pronounced among subgroups of aged <60 years, women, never drinkers, never smokers, persons with a normal BMI and those with a family history of cancer(P(trend)<0.01). Moreover, luciferase assays showed that the G allele in the 3'UTR significantly decreased NFκBIA mRNA stability and the A allele regulation by miRNA449a in vitro and that the NFκBIA protein expression levels of the AA+AG variant carriers were significantly higher in peritumoral tissues than those of the 2758GG genotype.

CONCLUSION

NFκB1 and NFκBIA polymorphisms appear to jointly contribute to risk of CRC. These two variants may be a genetic modifier for CRC susceptibility in this southern Chinese population.

NFKB1 insertion/deletion promoter polymorphism increases the risk of advanced ovarian cancer in a Chinese population

Ovarian cancer is the leading cause of death among all gynecological cancers. This is mainly attributed to its frequent presentation at an advanced stage (International Federation of Gynecology and Obstetrics stage III-IV). Nuclear factor-kappaB (NF-κB) is critically involved in the carcinogenesis and development of ovarian cancer. A functional insertion/deletion polymorphism (-94 ins/del ATTG) in the promoter region of the NFKB1 gene, which encodes the p50 subunit of the NF-κB protein, has been recently identified and shown to increase the susceptibility to many diseases. The purpose of this study was to explore the association between this polymorphism and the risk of advanced ovarian cancer in a Chinese population. A total of 179 advanced ovarian cancer patients and 223 healthy controls were recruited into this study. Genotypes were determined using polymerase chain reaction-capillary electrophoresis method. The insertion increased the risk of advanced ovarian cancer (odds ratio = 2.111, 95% confidence intervals = 1.125-3.961, p = 0.019 for heterozygote insertion, and odds ratio = 2.656, 95% confidence intervals = 1.397-5.051, p = 0.002 for homozygote insertion) compared with homozygote deletion. Similar results were seen in age-adjusted analyses (p < 0.05). Our preliminary results suggest that NFKB1-94 ins/del ATTG promoter polymorphism may be associated with increased susceptibility to advanced ovarian cancer.

Nuclear Factor (NF) kappaB polymorphism is associated with heart function in patients with heart failure

BACKGROUND

Cardiac remodeling is generally an adverse sign and is associated with heart failure (HF) progression. NFkB, an important transcription factor involved in many cell survival pathways, has been implicated in the remodeling process, but its role in the heart is still controversial. Recently, a promoter polymorphism associated with a lesser activation of the NFKB1 gene was also associated with Dilated Cardiomyopathy. The purpose of this study was to evaluate the association of this polymorphism with clinical and functional characteristics of heart failure patients of different etiologies.

METHODS

A total of 493 patients with HF and 916 individuals from a cohort of individuals from the general population were investigated. The NFKB1 -94 insertion/deletion ATTG polymorphism was genotyped by High Resolution Melt discrimination. Allele and genotype frequencies were compared between groups. In addition, frequencies or mean values of different phenotypes associated with cardiovascular disease were compared between genotype groups. Finally, patients were prospectively followed-up for death incidence and genotypes for the polymorphism were compared regarding disease onset and mortality incidence in HF patients.

RESULTS

We did not find differences in genotype and allelic frequencies between cases and controls. Interestingly, we found an association between the ATTG1/ATTG1 genotype with right ventricle diameter (P = 0.001), left ventricle diastolic diameter (P = 0.04), and ejection fraction (EF) (P = 0.016), being the genotype ATTG1/ATTG1 more frequent in patients with EF lower than 50% (P = 0.01). Finally, we observed a significantly earlier disease onset in ATTG1/ATTG1 carriers.

CONCLUSION

There is no genotype or allelic association between the studied polymorphism and the occurrence of HF in the tested population. However, our data suggest that a diminished activation of NFKB1, previously associated with the ATTG1/ATTG1 genotype, may act modulating on the onset of disease and, once the individual has HF, the genotype may modulate disease severity by increasing cardiac remodeling and function deterioration.

Identification of NF-kappaB1 and NF-kappaBIAlpha polymorphisms using PCR-RFLP assay in a Turkish population

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used in a Turkish population to determine the frequency of polymorphisms of the nuclear factor-kappa (NF-kappaB1) and NF-kappaBIA genes, which have been shown to be related to several inflammatory diseases and cancer pathogenesis. Total genomic DNA was isolated from peripheral blood samples taken from 565 healthy volunteers living in Aydin Province. The genomic regions in question were amplified by PCR, and the polymorphisms in these regions were detected by a PCR-RFLP assay. The frequencies were 10.3% for the NF-kappaB1 -94ins/delATTG del/del genotype, 49.1% for del/ins, and 40.6% for ins/ins. The genotype frequencies of the NF-kappaBIA 3'UTR A --> G genotypes were A/A 19.2%, A/G 42.3%, and G/G 38.5%. Distribution of genotype frequencies was tested by Hardy-Weinberg; the NF-kappaB1 gene was in Hardy-Weinberg equilibrium (chi(2) = 3.402, P > 0.05), the NF-kappaBIA gene was not (chi(2) = 8.293, P < 0.05).

A functional polymorphism of the NFKB1 gene increases the risk for alcoholic liver cirrhosis in patients with alcohol dependence

BACKGROUND

The genetic basis for the predisposition to alcoholic liver cirrhosis (ALC) remains unknown. Increasing evidence supports a role for the nuclear factor (NF)-kappaB, the NF-kappaB inhibitor alpha (NFKBIA), and the peroxisome proliferator-activated receptor (PPAR)-gamma in the pathogenesis of alcoholic liver disease, raising the possibility that common polymorphisms in genes encoding these molecules may confer susceptibility to ALC. The objective of this study was to analyze the relationship between common polymorphisms in NFKB1, NFKBIA, and PPARG2 genes and the presence of ALC.

METHODS

A total of 258 male alcoholics (161 without liver disease and 97 with ALC) and 101 healthy controls were genotyped for the -94ins/delATTG NFKB1, 3'-UTR+126G>A NFKBIA, and 34C>G PPARG2 polymorphisms. The association of these genetic variants with ALC was tested in alcoholic patients with alcohol abuse and alcohol dependence. A logistic regression analysis was further performed to analyze the model of inheritance.

RESULTS

We found an association between the presence of the deletion allele in NFKB1 polymorphism and ALC in patients with alcohol dependence. We found no association between NFKBIA and PPARG2 polymorphisms and the presence of ALC.

CONCLUSIONS

The deletion allele of the -94ins/del NFKB1 polymorphism could be associated with a higher risk of developing ALC through an increase in inflammation, as supported by previous data.

Association of NFkB1 -94ins/delATTG promoter polymorphism with ulcerative colitis in Chinese Han population of Hubei Province

AIM: To investigate the association between NFkB1 -94ins/delATTG promoter polymorphism and ulcerative colitis in Chinese Han population of Hubei Province.

METHODS: The NFkB1-94ins/delATTG promoter polymorphism was genotyped in 73 unrelated Chinese patients with ulcerative colitis and 121 healthy controls using polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). The correlation of allele and genotype frequencies for this locus with the clinical subtypes of ulcerative colitis was analyzed. The results were compared with those obtained in a previous study of Italian population.

RESULTS: No significant differences were found in genotype and allele frequencies of the NFkB1-94ins/delATTG promoter polymorphism between patients with ulcerative colitis and healthy controls. There was no significant correlation between allele and genotype frequencies for this locus and the clinical subtypes of ulcerative colitis (P > 0.05). However, the genotypes (χ² = 13.155, P < 0.05) and allele frequencies (OR = 0.566, 95%CI: 0.413-0.774, P < 0.01) for this locus were significantly different between the Chinese and Italian populations.

CONCLUSION: No association between NFkB1 -94ins/delATTG promoter polymorphism and ulcerative colitis is found in Chinese Han population of Hubei Province.

Primary Nasal Epithelium Exposed to House Dust Mite Extract Shows Activated Expression in Allergic Individuals

Nasal epithelial cells form the outermost protective layer against environmental factors. However, this defense is not just physical; it has been shown that epithelial cells respond by the production of inflammatory mediators that may affect local immune responses. In this research we set out to characterize potential differences between the responses of nasal epithelium from healthy and allergic individuals to house dust mite (HDM) allergen. These differences will help us to define local mechanisms that could contribute to allergic disease expression. Epithelial cells were cultured from nasal biopsies taken from five healthy and five allergic individuals. These cultures were exposed for 24 hours to culture medium containing HDM allergen, or to culture medium alone. Isolated RNA was used for microarray analysis. Gene-ontology of the response in healthy epithelium revealed mainly up-regulation of chemokines, growth factors, and structural proteins. Moreover, we saw increased expression of two transcription factors (NF-kappaB and AP-1) and their regulatory members. The expression pattern of epithelium from allergic individuals in the absence of the HDM stimulus suggests that it is already in an activated state. Most striking is that, while the already activated NF-kappaB regulatory pathway remained unchanged in allergic epithelium, the AP-1 pathway is down-regulated upon exposure to HDM allergen; this is contrary to what we see in healthy epithelium. Clear differences in the expression pattern exist between epithelial cells isolated from healthy and allergic individuals at baseline and between their responses to allergen exposure; these differences may contribute to the inflammatory response.

NFKB1 promoter variation implicates shear-induced NOS3 gene expression and endothelial function in prehypertensives and stage I hypertensives

In endothelial cells, NF-kappaB is an important intracellular signaling molecule by which changes in wall shear stress are transduced into the nucleus to initiate downstream endothelial nitric oxide synthase (NOS3) gene expression. We investigated whether NF-kappa light-chain gene enhancer in B cells 1 (NFKB1) promoter polymorphism ((-94)NFKB1 I/D, where I is the insertion allele and D is the deletion allele) was associated with 1) NOS3 gene expression in endothelial cells under physiological levels of unidirectional laminar shear stress (LSS) and 2) endothelial function in prehypertensive and stage I hypertensive individuals before and after a 6-mo supervised endurance exercise intervention. Competitive EMSAs revealed that proteins present in the nuclei of endothelial cells preferentially bound to the I allele NFKB1 promoter compared with the D allele. Reporter gene assays showed that the I allele promoter had significantly higher activity than the D allele. In agreement with these observations, homozygous II genotype cells had higher p50 expression levels than homozygous DD genotype cells. Cells with the homozygous II genotype showed a greater increase in NOS3 protein expression than did homozygous DD genotype cells under LSS. Functional experiments on volunteers confirmed higher baseline reactive hyperemic forearm blood flow, and, furthermore, the subgroup analysis revealed that DD homozygotes were significantly less prevalent in the exercise responder group compared with II and ID genotypes. We conclude that the (-94)NFKB1 I/D promoter variation contributes to the modulation of vascular function and adaptability to exercise-induced flow shear stress, most likely due to differences in NFKB1 gene transactivity.

Association screen for atopic dermatitis candidate gene regions using microsatellite markers in pooled DNA samples

Atopic dermatitis (AD) is a chronic inflammatory skin disease affecting up to 16% of children in developed countries. A complex genetic background for AD has been suggested, with genetic as well as environmental factors influencing disease susceptibility. Among other factors, dysregulation in both the innate and the adaptive immune system has been proposed to play a role in AD pathophysiology. We present here an extended association screen for AD using microsatellite markers in 154 genes related to innate and adaptive immunity in pooled DNA samples from 150 German children with AD and 100 controls. After Bonferroni correction, no marker revealed a significant association with AD. Yet, markers representing the nuclear factor kappa B (NFKB)1 and chemokine receptor (CCR)4 genes showed differences in allelic distributions between cases and controls for both pooled DNA analysis and individual genotyping and were thus further investigated. Evaluation of additional single nucleotide polymorphisms (SNP) in the NFKB1 and CCR4 genes revealed no association of individual SNPs with AD. In contrast, haplotype analyses showed a significantly different haplotype distribution between patients and controls for CCR4 (P < 0.001). Furthermore, when SNP-SNP interaction effects were analysed for these two genes, we found significant evidence for epistatic interactions between SNPs within each of the two genes but no evidence for a gene-gene interaction, suggesting that variation in or near both the CCR4 and the NFKB1 genes might individually contribute to AD pathogenesis.

NFkappaB and its inhibitor IkappaB in relation to type 2 diabetes and its microvascular and atherosclerotic complications

Nuclear factor kappa B (NFkappaB) is an important transcription factor that together with its inhibitor (IkappaB) participates in the activation of genes involved in immune responses. We examined the CA repeat polymorphism of the NFKB1 gene (encoding for NFkappaB) and A/G point variation in the 3'UTR region of the nuclear factor kappa B inhibitor alpha (NFKBIA) gene (encoding for IkappaB) in Czech and German patients with type 2 diabetes. The sample consisted of 211 patients, both with and without kidney complications, and 159 controls. Additionally, 152 patients with systemic lupus erythematosus (SLE) were genotyped for NFKBIA polymorphism. We observed a significant increase in the homozygous AA genotype of the NFKBIA gene when compared with the control group (the highest value was in diabetics without diabetic nephropathy [p(c)* = 0.0015, odds ratio = 3.59]). No differences were seen between the SLE and control groups. With regard to the polymorphism of the NFKB1 gene, we did not observe any significant differences between the groups. Since the AA genotype of the NFKBIA gene presents a risk for type 2 diabetes development but not for diabetic nephropathy alone, we believe that the NFkappaB gene polymorphism can influence the pathogenesis of diabetes mellitus and affect its complications. Negative findings relative to other inflammatory autoimmune diseases, such as SLE, suggest a specific relationship between NFkappaB and type 2 diabetes mellitus.

A NFKB1 promoter polymorphism is involved in susceptibility to ulcerative colitis

Nuclear factor kappaB (NF-kappaB) designates a group of critical transcription factors involved in a variety of immunologic and/or inflammatory processes. Conceivably, genes involved in the NF-kappaB pathway make interesting candidate genes for chronic inflammatory disorders, including the inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC). In two mouse models of colitis, strong linkage has been observed with a locus on chromosome 3 that harbours the Nfkb1 gene. In addition, a polymorphism in the promoter region of the human NFKB1 gene was found to be associated with susceptibility to UC. In this study, we searched to confirm this previously found association in IBD in a different population. Allele and genotype frequencies of the -94 ins/delATTG polymorphism were determined in 266 unrelated Dutch Caucasian IBD patients (127 UC, 139 CD), and 155 matched healthy controls. The allele frequency of the deletion was significantly higher in UC patients (P = 0.019), but not in CD patients, compared to healthy controls, and the UC patients homozygous for the -94 ATTG deletion had a younger age of onset. Our findings confirm the previously found association between this polymorphism and susceptibility to UC in an independent study population and adds further evidence for the role of this gene in disease susceptibility.

A functional polymorphism of the NFKB1 promoter is not associated with ulcerative colitis in a Spanish population

BACKGROUND

This study investigated the influence of the NFKB1-94ins/delATTG in the susceptibility/phenotype to ulcerative colitis.

METHODS

We analyzed the distribution of -94ins/delATTG NFKB1 in 258 patients and 264 healthy controls from southern Spain by a polymerase chain reaction-fluorescent method.

RESULTS

The genotype and allele frequencies of -94ins/delATTG did not significantly differ between patients and controls. In fact, the frequency of the -94delATTG allele was almost identical in both groups (34.8% and 35.4%, respectively), and the del/del genotype was underrepresented in UC patients (11.2% versus 14%). In addition, no association of this polymorphism was found with any of the clinical parameters analyzed.

CONCLUSION

These results suggest that the NFKB1 -94ins/delATTG gene variation, previously associated with UC susceptibility in North Americans, does not influence either susceptibility or phenotype of UC in the Spanish population.

NF-κB precursor, p105, and NF-κB inhibitor, IκBγ, are both elevated in Alzheimer disease brain

The nuclear factor-kappaB (NF-kappaB) signal transduction pathway regulates several vital cellular processes. During our studies of the glycoproteins involved in Alzheimer disease (AD), we found a significant increase of a 45-kDa protein band that was stained by lectin Maackia amurensis agglutinin (MAA). Mass spectrometry and Western blot analyses indicated that this 45-kDa MMA-positive protein was an inhibitor of NF-kappaB, IkappaBgamma. By Western blot analysis, the levels of both IkappaBgamma and NF-kappaB precursor, p105, were found to be elevated in AD brain as compared to age-matched controls. Our findings suggest that the NF-kappaB pathway might be involved in the molecular mechanism of AD.

I?B? is expressed in mast cells

IkappaBgamma (IkappaBgamma) is a 70-kDa protein that is encoded by the C-terminal part of the NF-kappaB p105 gene and acts as an inhibitor of the transcription factor NF-kappaB. Until now, IkappaBgamma expression has only been described in cell-culture models of B-lymphocytes and enterocytes but not in tissues. In a model of radiation-induced pulmonary damage, we found that mast cells accumulating after irradiation are the only cells in the rat lung that are positive for IkappaBgamma. The mast cells were characterised by their metachromatic staining with toluidine blue and by double immunofluorescence labelling with mast-cell tryptase. Western blotting revealed that the lung mast cells expressed the 70-kDa form of IkappaBgamma cytoplasmatically and that no alternative splicing variants were expressed. In addition, we studied 11 cases of systemic mastocytosis, as well as 5 cases of mast-cell hyperplasia. In all cases, the mast cells stained strongly with IkappaBgamma. Rat peritoneal mast cells also contained high levels of IkappaBgamma. Since NF-kappaB is an important regulator of mast-cell functions, IkappaBgamma is likely to play a central role in the maintenance of the mast-cell phenotype and possibly in the modification of mast-cell-dependent immune responses.

CA microsatellite polymorphism of the nuclear factor kappa B1 gene in celiac disease

In the present work, we investigate the possible effect of a CAn microsatellite polymorphism in the nuclear factor kappa B1 (NFKB1) gene on predisposition to celiac disease (CD). Seventy-eight Spanish families with CD were genotyped using a polymerase chain reaction (PCR)-fluorescent method, and the transmission patterns of different CAn alleles were analysed. Furthermore, in order to type the CAn polymorphism more accurately, samples between 126 and 144 bp were cloned and sequenced. A trend of association with the 132-bp allele was found (P = 0.02). This allele was more frequently transmitted to affected sibs, although the results of statistical tests were not significant after correction for multiple comparisons. After sequencing, we found that the 132-, 138- and 142-bp alleles had two As at the end of the CA microsatellite, with the other alleles presenting the described pattern (NCB1 nucleotide U60337) for the microsatellite repeats. These results suggest that the NFKB1 CAn microsatellite does not play a major role in CD susceptibility. In addition, a more detailed molecular characterization of the CA microsatellite is described.

Functional annotation of a novel NFKB1 promoter polymorphism that increases risk for ulcerative colitis

Nuclear Factor-kappaB (NF-kappaB) is a major transcription regulator of immune response, apoptosis and cell-growth control genes, and is upregulated in inflammatory bowel disease (IBD), both ulcerative colitis (UC) and Crohn's disease. The NFKB1 gene encodes the NF-kappaB p105/p50 isoforms. Genome-wide screens in IBD families show evidence for linkage on chromosome 4q where NFKB1 maps. We sequenced the NFKB1 promoter, exon 1 and all coding exons in 10 IBD probands and two controls, and identified six nucleotide variants, including a common insertion/deletion promoter polymorphism (-94ins/delATTG). Using pedigree-based transmission disequilibrium tests, we observed modest evidence for linkage disequilibrium (LD), independent of linkage, between the -94delATTG allele and UC in 131 out of 235 IBD pedigrees with UC offspring (P=0.047-0.052). This allele was also more frequent in the 156 non-Jewish UC probands from the 235 IBD pedigrees than in 149 non-Jewish controls (P=0.015). The -94delATTG association with UC was replicated in a second set of 258 unrelated, non-Jewish UC cases and 653 new, non-Jewish controls (P=0.021). Nuclear proteins from normal human colon tissue and colonic cell lines, but not ileal tissue, showed significant binding to -94insATTG but not to -94delATTG containing oligonucleotides. NFKB1 promoter/exon 1 luciferase reporter plasmid constructs containing the -94delATTG allele and transfected into either HeLa or HT-29 cell lines showed less promoter activity than comparable constructs containing the -94insATTG allele. Therefore, we have identified the first potentially functional polymorphism of NFKB1 and demonstrated its genetic association with a common human disease, ulcerative colitis.

Inhibitors in the NFkappaB cascade comprise prime candidate genes predisposing to multiple sclerosis, especially in selected combinations

Multiple sclerosis (MS) is an autoimmune disease displaying different clinical courses. In this multifactorial disease complex environmental as well as genetic predisposition factors contribute to the disease manifestation. Following the candidate gene approach we analysed several genes of the NFkappaB cascade, which are prime candidates for MS because of their involvement in almost all immunological reactions. MS association was excluded for the NFKB1 and NFKB3 genes, which show remarkably low degrees of polymorphism. The genes of NFkappaB inhibitors exhibit more sequence variations. In the IKBL gene a predisposing allele was identified (13.1% vs 7.5% in the control group, P < 0.001). This difference in the allelic distribution was even increased in the group of MS patients with a relapsing remitting course of the disease (14.9%, P < 0.0001). A protecting allele was found in the NFKBIA promotor for the patients with primary progressive MS (15.4% vs 28.4% in the control group, P < 0.01). Given predisposing alleles increase MS risk dramatically in certain combinations.

DIFFERENTIAL NF-??B AND I??B GENE EXPRESSION DURING DEVELOPMENT OF CARDIAC ALLOGRAFT REJECTION VERSUS CD154 MONOCLONAL ANTIBODY-INDUCED TOLERANCE1

BACKGROUND

The Rel/NF-kappaB transcription factor pathway, regulated by IkappaB proteins, is considered central to immune responses, although there are surprisingly few in vivo data concerning alloresponses.

METHODS

We undertook analysis of NF-kappaB and IkappaB mRNA intracardiac allograft expression, and NF-kappaB nuclear translocation, during acute rejection versus CD154 monoclonal antibody (mAb)-induced tolerance induction in fully MHC-disparate mice.

RESULTS

Intragraft expression of all nine NF-kappaB and IkappaB genes increased during development of rejection, and nuclear translocation of p50, p52, and p65 was detected. CD154 mAb therapy decreased mRNA levels of all nine NF-kappaB and IkappaB genes, and impaired nuclear translocation of p50, p52, and p65 NF-kappaB proteins. However, prolonged survival could not be induced by CD154 mAb in p50- or p52-deficient allograft recipients, indicating an absolute requirement for expression of these genes in CD154 mAb-induced tolerance.

CONCLUSIONS

We conclude that, whereas blanket approaches to NF-kappaB suppression are unlikely to be effective strategies for tolerance induction, a better understanding of the roles of individual NF-kappaB and IkappaB genes may allow development of more precise and effective therapies.

Shared pathways of IkappaB kinase-induced SCF(betaTrCP)-mediated ubiquitination and degradation for the NF-kappaB precursor p105 and IkappaBalpha

p105 (NFKB1) acts in a dual way as a cytoplasmic IkappaB molecule and as the source of the NF-kappaB p50 subunit upon processing. p105 can form various heterodimers with other NF-kappaB subunits, including its own processing product, p50, and these complexes are signal responsive. Signaling through the IkappaB kinase (IKK) complex invokes p105 degradation and p50 homodimer formation, involving p105 phosphorylation at a C-terminal destruction box. We show here that IKKbeta phosphorylation of p105 is direct and does not require kinases downstream of IKK. p105 contains an IKK docking site located in a death domain, which is separate from the substrate site. The substrate residues were identified as serines 923 and 927, the latter of which was previously assumed to be a threonine. S927 is part of a conserved DSGPsi motif and is functionally most critical. The region containing both serines is homologous to the N-terminal destruction box of IkappaBalpha, -beta, and -epsilon. Upon phosphorylation by IKK, p105 attracts the SCF E3 ubiquitin ligase substrate recognition molecules betaTrCP1 and betaTrCP2, resulting in polyubiquitination and complete degradation by the proteasome. However, processing of p105 is independent of IKK signaling. In line with this and as a physiologically relevant model, lipopolysaccharide (LPS) induced degradation of endogenous p105 and p50 homodimer formation, but not processing in pre-B cells. In mutant pre-B cells lacking IKKgamma, processing was unaffected, but LPS-induced p105 degradation was abolished. Thus, a functional endogenous IKK complex is required for signal-induced p105 degradation but not for processing.

Chronic antagonism of nuclear factor-kappaB activity in cytotrophoblasts by dexamethasone: a potential mechanism for antiinflammatory action of glucocorticoids in human placenta

Circulating glucocorticoids are present in increasing quantities as human gestation progresses, peaking during labor whether it occurs before or at term. Although the precise role of glucocorticoids in pregnancy is not well defined, it is clear that glucocorticoids suppress inflammation in many cell types by antagonizing the acute stimulatory actions of members of the Rel/nuclear factor-kappaB (NF-kappaB) family on cytokine gene expression. In the present study we tested the hypothesis that during pregnancy, glucocorticoids chronically suppress inflammation in the human placenta. Cytotrophoblasts obtained from human term placentas were maintained for 48 h in culture medium supplemented with 10% charcoal-stripped calf serum with and without 100 nmol/L dexamethasone (DEX). Enzyme-linked immunosorbent assay studies revealed that cytotrophoblasts constitutively express interleukin-8 (IL-8), a known mediator of placental inflammation, between 24-96 h of culture. A 48-h treatment of cytotrophoblasts with 100 nmol/L DEX significantly reduced the production of IL-8 to 24+/-1% of control levels (P < 0.01). DEX and cortisol mediated a dose-dependent inhibition of IL-8 expression, with ED50 values of 5 and 50 nmol/L, respectively. DEX treatment also significantly reduced levels of IL-6 and tumor necrosis factor-alpha in culture medium, suggesting that glucocorticoids coordinately reduce cytokine levels in cytotrophoblasts. As cytokine expression is regulated by NF-kappaB and activator protein-1 (AP-1) transcription factors, electrophoretic mobility shift assays (n = 4) were used to determine whether DEX treatment altered the binding of nuclear proteins from cytotrophoblasts to labeled oligonucleotides corresponding to the kappaB and AP-1 response elements. We observed that a 48-h treatment of cytotrophoblasts with 100 nmol/L DEX markedly reduced binding of nuclear extracts from cytotrophoblasts to the kappaB response element. DEX treatment promoted a relatively smaller reduction of binding to the AP-1 response element. Northern blotting experiments revealed that DEX treatment did not alter the level of IkappaB, p50, or p65 messenger ribonucleic acid, suggesting that the antiinflammatory action of glucocorticoid in cytotrophoblasts did not directly involve alterations in the level of NF-kappaB proteins. Our results demonstrate a novel chronic suppressive action of glucocorticoid on cytokine production and nuclear binding of NF-kappaB and AP-1 proteins in cytotrophoblasts, providing a potential mechanism through which glucocorticoids may suppress inflammation at maternal-fetal interfaces across gestation.

NF-kappa B p105 processing via the ubiquitin-proteasome pathway

The p50 subunit of NF-kappa B is generated by proteolytic processing of a 105-kDa precursor (p105) in yeast and mammalian cells. Here we show that yeast mutants in the ubiquitin-proteasome pathway inhibit or abolish p105 processing. Specifically, p105 processing is inhibited by a mutation in a 20 S proteasome subunit (pre1-1), by mutations in the ATPases located in the 19 S regulatory complexes of the proteasome (yta1, yta2/sug1, yta5, cim5), and by a mutation in a proteasome-associated isopeptidase (doa4). A ubiquitinated intermediate of the p105 processing reaction accumulates in some of these mutants, strongly suggesting that ubiquitination is required for processing. However, none of the ubiquitin conjugating enzyme mutants tested (ubc1, -2, -3, -4/5, -6/7, -8, -9, -10, -11) had an effect on p105 processing, suggesting that more than one of these enzymes is sufficient for p105 processing. Interestingly, a mutant "N-end rule" ligase does not adversely affect p105 processing, showing that the N-end rule pathway is not involved in degrading the C-terminal region of p105. Unexpectedly, we found that a glycine-rich region of p105 that is required for p105 processing in mammalian cells is not required for processing in yeast. Thus, p105 processing in both yeast and mammalian cells requires the ubiquitin-proteasome pathway, but the mechanisms of processing, while similar, are not identical.