Upstream stimulating factors: highly versatile stress-responsive transcription factors

Phosphorylation of E-box binding USF-1 by PI3K/AKT enhances its transcriptional activation of the WBP2 oncogene in breast cancer cells

WW domain binding protein 2 (WBP2), a transcriptional coactivator, plays a vital role in breast tumorigenesis. It positively regulates estrogen receptor, Hippo, and Wnt pathways, which subsequently enhance the transcription of downstream target genes contributing to cancer. Understanding the regulation of the expression and activity of WBP2 oncoprotein has implication in cancer therapy. We have previously reported that WBP2 is regulated at the post-translational and post-transcriptional levels. However, its regulation at the transcriptional level is not known. In this study, the minimal promoter region of WBP2 that is critical for its transcription was identified. The E-box motif in the WBP2 promoter was demonstrated to be essential for its transcription. The E-box binding protein upstream stimulatory factor 1 (USF-1) was discovered to be a key transcription factor for WBP2 by yeast one-hybrid analysis and was validated through reporter and chromatin immunoprecipitation assays and tandem mass spectrometry, which also suggested that USF-1 acts by regulating a network of genes, in addition to WBP2, associated with cell movement, proliferation, cell-cycle, and survival cellular processes. USF-1 is overexpressed in majority of the breast cancer cell lines and tissues tested, and has profound effects on cancer cell proliferation. USF-1-mediated transcription of WBP2 was demonstrated to be inducible by insulin, which led to AKT-mediated phosphorylation of USF-1 that modulated its ability to bind to the WBP2 promoter and activate its transcription. This study sheds new light onto the regulation of the WBP2 oncogene at the transcriptional level by a novel oncogenic transcription factor, USF-1. USF-1 is a potential drug target for treatment of WBP2-positive breast cancer.-Ramos, A., Miow, Q. H., Liang, X., Lin, Q. S., Putti, T. C., Lim, Y. P. Phosphorylation of E-box binding USF-1 by PI3K/AKT enhances its transcriptional activation of the WBP2 oncogene in breast cancer cells.

Upstream stimulating factor 1 suppresses autophagy and hepatic lipid droplet catabolism by activating mTOR

Previous studies indicate that the transcription factor upstream stimulating factor 1 (USF1) is involved in the regulation of lipid and glucose metabolism. However, the role of USF1 in lipid-induced autophagy remains unknown. Interestingly, we found that USF1 overexpression suppresses autophagy-related gene expression in HepG2 cells. Further assays confirmed that USF1 could transcriptionally activate mTOR expression, thereby suppressing rapamycin-induced autophagy in HepG2 cells. Moreover, pharmacological activation of autophagy with rapamycin decreases the numbers and sizes of lipid droplets (LDs) in HepG2 cells exposed to an oleate/palmitate mixture. Of note, USF1 upregulation decreases colocalization of LDs and autophagosomes. In conclusion, our data provide evidence that USF1 contributes to abnormal lipid accumulation in the liver by suppressing autophagy via regulation of mTOR transcription.

Interleukin-like EMT inducer (ILEI) promotes melanoma invasiveness and is transcriptionally up-regulated by upstream stimulatory factor-1 (USF-1)

Interleukin-like EMT inducer (ILEI, FAM3C) is a secreted factor that contributes to the epithelial-to-mesenchymal transition (EMT), a cell-biological process that confers metastatic properties to a tumor cell. However, very little is known about how ILEI is regulated. Here we demonstrate that ILEI is an in vivo regulator of melanoma invasiveness and is transcriptionally up-regulated by the upstream stimulatory factor-1 (USF-1), an E-box-binding, basic-helix-loop-helix family transcription factor. shRNA-mediated knockdown of ILEI in melanoma cell lines attenuated lung colonization but not primary tumor formation. We also identified the mechanism underlying ILEI transcriptional regulation, which was through a direct interaction of USF-1 with the ILEI promoter. Of note, stimulation of endogenous USF-1 by UV-mediated activation increased ILEI expression, whereas shRNA-mediated USF-1 knockdown decreased ILEI gene transcription. Finally, we report that knocking down USF-1 decreases tumor cell migration. In summary, our work reveals that ILEI contributes to melanoma cell invasiveness in vivo without affecting primary tumor growth and is transcriptionally up-regulated by USF-1.

The Glucose-Regulated MiR-483-3p Influences Key Signaling Pathways in Cancer

The hsa-mir-483 gene, located within the IGF2 locus, transcribes for two mature microRNAs, miR-483-5p and miR-483-3p. This gene, whose regulation is mediated by the the CTNNB1/USF1 complex, shows an independent expression from its host gene IGF2. The miR-483-3p affects the Wnt/β-catenin, the TGF-β, and the TP53 signaling pathways by targeting several genes as CTNNB1, SMAD4, IGF1, and BBC3. Accordingly, miR-483-3p is associated with various tissues specific physiological properties as insulin and melanin production, as well as with cellular physiological functions such as wounding, differentiation, proliferation, and survival. Deregulation of miR-483-3p is observed in different types of cancer, and its overexpression can inhibit the pro-apoptotic pathway induced by the TP53 target effectors. As a result, the oncogenic characteristics of miR-483-3p are linked to the effect of some of the most relevant cancer-related genes, TP53 and CTNNB1, as well as to one of the most important cancer hallmark: the aberrant glucose metabolism of tumor cells. In this review, we summarize the recent findings regarding the miR-483-3p, to elucidate its functional role in physiological and pathological contexts, focusing overall on its involvement in cancer and in the TP53 pathway.

COX-2 gene expression and methylation profile in Sapajus apella as an experimental model for gastric adenocarcinoma

Gastric cancer (GC) remains one of the main causes of cancer-related death worldwide. There are two distinct histological types of GC: diffuse and intestinal. The latter is characterized by the presence of pre-neoplastic lesions. One of the most frequently altered enzymes in intestinal GC is COX-2, an important lesion marker. This work aimed to study COX-2 methylation and expression in N-methyl-N-Nitrosurea (MNU)-induced intestinal GC in six Sapajus apella animals. The partial promoter sequence of S. apella COX-2 gene was obtained and used to identify transcription factors and cis-regulatory element binding sites. The COX-2 methylation pattern was assessed using Methylation-Specific PCR (MSP), and expression was analyzed by immunohistochemistry (IHQ). A total of 20 samples were obtained. A 675 bp fragment of the S. apella COX-2 promoter region was obtained, and it was 99.2% and 68.2% similar to H. sapiens and S. boliviensis, respectively. Similar to humans, several transcription factors and cis-regulatory element binding sites were identified in the S. apella sequence. MSP revealed that all samples were methylated. However, IHQ results demonstrated positive COX-2 expression in all pre-neoplastic and tumoral samples. The results suggest that the analyzed fragment is not crucial in COX-2 regulation of GC in S. apella.

Role of upstream stimulatory factor 2 in glutamate dehydrogenase gene transcription

Glutamate dehydrogenase (Gdh) plays a central role in ammonia detoxification by catalysing reversible oxidative deamination of l-glutamate into α-ketoglutarate using NAD⁺ or NADP⁺ as cofactor. To gain insight into transcriptional regulation of glud, the gene that codes for Gdh, we isolated and characterised the 5' flanking region of glud from gilthead sea bream (Sparus aurata). In addition, tissue distribution, the effect of starvation as well as short- and long-term refeeding on Gdh mRNA levels in the liver of S. aurata were also addressed. 5'-Deletion analysis of glud promoter in transiently transfected HepG2 cells, electrophoretic mobility shift assays, chromatin immunoprecipitation (ChIP) and site-directed mutagenesis allowed us to identify upstream stimulatory factor 2 (Usf2) as a novel factor involved in the transcriptional regulation of glud Analysis of tissue distribution of Gdh and Usf2 mRNA levels by reverse transcriptase-coupled quantitative real-time PCR (RT-qPCR) showed that Gdh is mainly expressed in the liver of S. aurata, while Usf2 displayed ubiquitous distribution. RT-qPCR and ChIP assays revealed that long-term starvation down-regulated the hepatic expression of Gdh and Usf2 to similar levels and reduced Usf2 binding to glud promoter, while refeeding resulted in a slow but gradual restoration of both Gdh and Usf2 mRNA abundance. Herein, we demonstrate that Usf2 transactivates S. aurata glud by binding to an E-box located in the proximal region of glud promoter. In addition, our findings provide evidence for a new regulatory mechanism involving Usf2 as a key factor in the nutritional regulation of glud transcription in the fish liver.

Upstream Stimulating Factor 1 (USF-1) Gene Polymorphisms and the Risk, Symptoms, and Outcome of Pediatric Ischemic Stroke

BACKGROUND

Pediatric ischemic stroke is an important cause of morbidity and mortality. As previous studies of children after stroke showed, dyslipidemias were very common in Polish and other European populations. Thus, looking for genetic factors predisposing to pediatric stroke, its symptoms, and outcome, we have analyzed 2 polymorphisms of the upstream stimulating factor 1 (USF-1) gene.

MATERIALS AND METHODS

The study group consisted of 82 children with stroke, 156 parents, and 146 controls. We used 2 alternative methods: the case-control model and the analysis of families using the transmission disequilibrium test. The 2 polymorphisms, rs2516839 and rs3737787, were genotyped using the TaqMan Pre-Designed SNP Genotyping Assay. The Statistica 10.0 software was used in all statistical analyses.

RESULTS

We did not observe any statistical differences in genotype and allele frequencies between patients and controls. There were also no significant differences in the transmission of alleles from the parents to the affected children. However, we have observed that the TT genotype of the rs2516839 polymorphism was more common in patients with epilepsy and dysarthria, whereas the TT genotype of the rs3737787 polymorphism was more frequent in the group of patients with a decrease in intellectual functioning.

CONCLUSIONS

Our study did not show any associations between the 2 analyzed polymorphisms of the USF-1 gene and pediatric ischemic stroke. However, we have observed an influence of specific genotypes on the outcome of stroke, including epilepsy, dysarthria, and a decrease in intellectual functioning.

Clustering gene expression time series data using an infinite Gaussian process mixture model

Transcriptome-wide time series expression profiling is used to characterize the cellular response to environmental perturbations. The first step to analyzing transcriptional response data is often to cluster genes with similar responses. Here, we present a nonparametric model-based method, Dirichlet process Gaussian process mixture model (DPGP), which jointly models data clusters with a Dirichlet process and temporal dependencies with Gaussian processes. We demonstrate the accuracy of DPGP in comparison to state-of-the-art approaches using hundreds of simulated data sets. To further test our method, we apply DPGP to published microarray data from a microbial model organism exposed to stress and to novel RNA-seq data from a human cell line exposed to the glucocorticoid dexamethasone. We validate our clusters by examining local transcription factor binding and histone modifications. Our results demonstrate that jointly modeling cluster number and temporal dependencies can reveal shared regulatory mechanisms. DPGP software is freely available online at https://github.com/PrincetonUniversity/DP_GP_cluster.

Functional interplay between the transcription factors USF1 and PDX-1 and protein kinase CK2 in pancreatic β-cells

Glucose homeostasis is regulated by insulin, which is produced in the β-cells of the pancreas. The synthesis of insulin is controlled by several transcription factors including PDX-1, USF1 and USF2. Both, PDX-1 and USF1 were identified as substrates for protein kinase CK2. Here, we have analysed the interplay of PDX-1, USF1 and CK2 in the regulation of PDX-1 gene transcription. We found that the PDX-1 promoter is dose-dependently transactivated by PDX-1 and transrepressed by USF1. With increasing glucose concentrations the transrepression of the PDX-1 promoter by USF1 is successively abrogated. PDX-1 binding to its own promoter was not influenced by glucose, whereas USF1 binding to the PDX-1 promoter was reduced. The same effect was observed after inhibition of the protein kinase activity by three different inhibitors or by using a phospho-mutant of USF1. Moreover, phosphorylation of USF1 by CK2 seems to strengthen the interaction between USF1 and PDX-1. Thus, CK2 is a negative regulator of the USF1-dependent PDX-1 transcription. Moreover, upon inhibition of CK2 in primary islets, insulin expression as well as insulin secretion were enhanced without affecting the viability of the cells. Therefore, inhibition of CK2 activity may be a promising approach to stimulate insulin production in pancreatic β-cells.

Genetic variation in the MITF promoter affects skin colour and transcriptional activity in black-boned chickens

1. Microphthalmia-associated transcription factor (MITF) plays a pivotal role in melanocyte development by regulating the transcription of major pigmentation enzymes (e.g. TYR, TYRP1 and DCT). A single-nucleotide polymorphism (SNP), c.-638T>C, was identified in the MITF promoter, and genotyping of a population (n = 426) revealed that SNP c.-638T>C was associated with skin colour in black-boned chickens. 2. Individuals with genotypes CC and TC exhibited greater MTIF expression than those with genotype TT. Luciferase assays also revealed that genotype CC and TC promoters had higher activity levels than genotype TT. Expression of melanogenesis-related gene (TYR) was higher in the skin of chickens with the CC and CT genotype compared to TT chickens (P < 0.05). 3. Transcription factor-binding site analyses showed that the c.-638C allele contains a putative binding site for transcription factor sterol regulatory element-binding transcription factor 2, aryl hydrocarbon receptor nuclear translocator, transcription factor binding to IGHM enhancer 3 and upstream transcription factor 2. In contrast, the c.-638T allele contains binding sites for Sp3 transcription factor and Krüppel-like factor 1. 4. It was concluded that MITF promoter polymorphisms affected chicken skin colour. SNP c.-638T>C could be used for the marker-assisted selection of skin colour in black-boned chicken breeding.

Minimal Purkinje Cell-Specific PCP2/L7 Promoter Virally Available for Rodents and Non-human Primates

Cell-type-specific promoters in combination with viral vectors and gene-editing technology permit efficient gene manipulation in specific cell populations. Cerebellar Purkinje cells play a pivotal role in cerebellar functions. Although the Purkinje cell-specific L7 promoter is widely used for the generation of transgenic mice, it remains unsuitable for viral vectors because of its large size (3 kb) and exceedingly weak promoter activity. Here, we found that the 0.8-kb region (named here as L7-6) upstream of the transcription initiation codon in the first exon was alone sufficient as a Purkinje cell-specific promoter, presenting a far stronger promoter activity over the original 3-kb L7 promoter with a sustained significant specificity to Purkinje cells. Intravenous injection of adeno-associated virus vectors that are highly permeable to the blood-brain barrier confirmed the Purkinje cell specificity of the L7-6 in the CNS. The features of the L7-6 were also preserved in the marmoset, a non-human primate. The high sequence homology of the L7-6 among mouse, marmoset, and human suggests the preservation of the promoter strength and Purkinje cell specificity features also in humans. These findings suggest that L7-6 will facilitate the cerebellar research targeting the pathophysiology and gene therapy of cerebellar disorders.

The Role of HOTAIR/miR-148b-3p/USF1 on Regulating the Permeability of BTB

Homeobox transcript antisense intergenic RNA (HOTAIR), as a long non-coding RNA (lncRNA), has been considered to play critical roles in the biological properties of various tumors. The purposes of this study were to investigate the role and possible molecular mechanisms of HOTAIR in regulating the permeability of blood tumor barrier (BTB) in vitro. Our present study elucidated that the expressions of HOTAIR and upstream stimulatory factor 1 (USF1) was up-regulated, but miR-148b-3p was down-regulated in glioma microvascular endothelial cells (GECs). Knockdown of HOTAIR could increase the permeability of BTB as well as down-regulated the expressions of tight junction related proteins ZO-1, occludin, claudin-5, but up-regulated miR-148b-3p expressions in GECs. Meanwhile, dual-luciferase reporter assays demonstrated that HOTAIR was a target RNA of miR-148b-3p. Furthermore, overexpression of miR-148b-3p increased the permeability of BTB by down-regulating the expressions of tight junction related proteins and USF1 in GECs, and vice versa. And further result revealed USF1 was a target of miR-148b-3p. Silence of USF1 increased the permeability of BTB duo to their interaction with the promoters of ZO-1, occludin, and claudin-5 in GECs. Taken together, our finding indicated that knockdown of HOTAIR increased BTB permeability via binding to miR-148b-3p, which further reducing tight junction related proteins in GECs by targeting USF1. Thus, HOTAIR will attract more attention since it can serve as a potential target of drug delivery across BTB and may provide novel strategies for glioma treatment.

Regulation of miR-483-3p by the O-linked N-acetylglucosamine transferase links chemosensitivity to glucose metabolism in liver cancer cells

The miR-483-3p is upregulated in several tumors, including liver tumors, where it inhibits TP53-dependent apoptosis by targeting the pro-apoptotic gene BBC3/PUMA. The transcriptional regulation of the miR-483-3p could be driven by the β-catenin/USF1 complex, independently from its host gene IGF2, and we previously demonstrated that in HepG2 hepatoblastoma cells carrying wild-type TP53 the upregulation of the miR-483-3p overcomes the antitumoral effects of the tumor-suppressor miR-145-5p by a mechanism involving cellular glucose availability. Here we demonstrate that in HepG2 cells, the molecular link between glucose concentration and miR-483-3p expression entails the O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT), which stabilizes the transcriptional complex at the miR-483 promoter. HepG2 cells showed reduced miR-483-3p expression and increased susceptibility to 5-fluorouracil (5-FU)-induced apoptosis in presence of the inhibitor of glycolysis 2-deoxy-d-glucose (2-DG). However, in vivo experiments showed that HepG2 cells with higher miR-483-3p expression were selected during tumor progression regardless of 5-FU treatment. Furthermore, treatment with 2-DG alone did not significantly reduce HepG2 xenograft load in immunodeficient mice. In conclusion, we show that in HepG2 cells glucose uptake increases the expression of the oncogenic miR-483-3p through the OGT pathway. This suggests that depletion of the miR-483-3p may be a valuable therapeutic approach in liver cancer patients, but the use of inhibitors of glycolysis to achieve this purpose could accelerate the selection of resistant neoplastic cell clones.

Histone deacetylase inhibitor apicidin increases expression of the α-secretase ADAM10 through transcription factor USF1-mediated mechanisms

ADAM10 (a disintegrin and metalloproteinase domain-containing protein 10) is the α-secretase that is involved in APP (β-amyloid precursor protein) processing. Enhancement of the nonamyloidogenic APP pathway by ADAM10 provides therapeutic potential for Alzheimer's disease (AD). By using high-throughput screening that targeted ADAM10, we determined that apicidin-an inhibitor of HDACs (histone deacetylases)-significantly increased mRNA and protein levels of ADAM10 in SH-SY5Y cells. A luciferase assay revealed that the nucleotides -444 to -300 in the ADAM10 promoter were sufficient to mediate this effect. In addition, knockdown of USF1 (upstream transcription factor 1) and HDAC2/3 prevented apicidin regulation of ADAM10. Moreover, USF1 acetylation was increased by apicidin, which enhanced the association of USF1 with HDAC2/3 and with the ADAM10 promoter. We further found that apicidin did not affect the phosphorylation of ERK or USF1; however, ERK inhibitor U0126 blocked the effect of apicidin on ADAM10. Finally, apicidin increased the level of α-site C-terminal fragment from APP and reduced the production of β-amyloid peptide 1-42. Collectively, our study provides evidence that ADAM10 expression can be regulated by HDAC2/3 inhibitor apicidin via USF1-dependent mechanisms in which ERK signaling plays an important role. Thus, HDAC regulation of ADAM10 might shed new light on the understanding of AD pathology.-Hu, X.-T., Zhu, B.-L., Zhao, L.-G., Wang, J.-W., Liu, L., Lai, Y.-J., He, L., Deng, X.-J., Chen, G.-J. Histone deacetylase inhibitor apicidin increases expression of the α-secretase ADAM10 through transcription factor USF1-mediated mechanisms.

Association between single nucleotide polymorphisms of upstream transcription factor 1 (USF1) and susceptibility to papillary thyroid cancer

BACKGROUND

Thyroid cancer, predominantly by papillary thyroid cancer (PTC), is a malignant tumour of endocrine system with increasing incidence rate worldwide. Upstream transcription factor 1 (USF1) regulates a variety of biological processes by transactivation of functional genes. In this study, we investigated the association between USF1 polymorphisms and PTC risk.

MATERIAL & METHODS

A total of 334 patients with PTC, 186 patients with benign nodules (BN) and 668 healthy controls were enrolled in our study. Tag-SNPs were identified in Chinese Han in Beijing (CHB) from International HapMap Project Databases. Genomic DNAs were extracted by TaqMan Blood DNA kits. SNPs of USF1 were genotyped by TaqMan SNPs genotyping assay. Odds ratios (OR) and corresponding 95% confidence interval (CI) were used to assess the association between USF1 genetic variants and PTC risk. The statistical analyses were carried out with spss 13.0 software.

RESULTS

Five tag-SNPs were retrieved to capture all the genetic variants of USF1. Among the five tag-SNPs, genetic variants in rs2516838, rs3737787 and rs2516839 have significant association with PTC risk. The rs2516838 polymorphisms dominant model (CG+GG vs CC: OR = 0·71; 95% CI: 0·52-0·97; P = 0·033) and allelic model (C vs G: OR = 0·031; 95% CI: 0·56-0·97; P = 0·031) indicated it may act as a protective factor against PTC. On the contrary, the results of rs3737787 polymorphisms: dominant model (CT+TT vs CC: OR = 1·55; 95%CI: 1·09-2·02; P = 0·001) and allelic model (C vs T: OR = 1·35; 95%CI: 1·10-1·64; P = 0·003), as well as the results of rs2516839 polymorphisms: dominant model (GA+AA vs GG: OR = 1·77; 95%CI: 1·31-2·38; P < 0·001) and allelic model (G vs A: OR = 1·36; 95%CI: 1·13-1·63; P = 0·014), revealed that they may act as risk factors for PTC.

CONCLUSION

In this study, we found the SNPs of rs2516838 (mutant G alleles vs wild C alleles), rs3737787 (mutant T alleles vs wild C alleles) and rs2516839 (mutant A alleles vs wild G alleles) were significantly associated with PTC risk. Further large-scale studies with different ethnicities are still needed to validate our findings and explore the underlying mechanism of USF1 in PTC development.

Basal transcription of APOBEC3G is regulated by USF1 gene in hepatocyte

Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G, A3G) exert antiviral defense as an important factor of innate immunity. A variety of cytokines such as IFN-γ、IL2、IL15、IL7 could induce the transcription of A3G. However, the regulation of other nuclear factor on the transcription of A3G have not been reported at the present. To gain new insights into the transcriptional regulation of this restriction factor, we cloned and characterized the promoter region of A3G and investigate the modulation of USF1 gene on the transcription of A3G. We identified a 232 bp region that was sufficient to regulate the activity of full promoter. Transcriptional start sites (TSS) were identified by the luciferase reporter assays of plasmids containing full or shorter fragments of the A3G promoter. The results demonstrated that the core promoter of A3G is located within the region -159/-84 relative to the TSS. Transcriptional activity of A3G core promoter regulated by USF1 was dependent on an E-box (located at position -91/-86 relative to the major TSS) and was abolished after mutation of this DNA element. USF1 gene can take part in basal transcription regulation of the human A3G gene in hepatocyte, and the identified E-box represented a binding site for the USF1.

Helicobacter pylori-induced inflammation and epigenetic changes during gastric carcinogenesis

The sequence of events associated with the development of gastric cancer has been described as “the gastric precancerous cascade”. This cascade is a dynamic process that includes lesions, such as atrophic gastritis, intestinal metaplasia and dysplasia. According to this model, Helicobacter pylori (H. pylori) infection targets the normal gastric mucosa causing non-atrophic gastritis, an initiating lesion that can be cured by clearing H. pylori with antibiotics or that may then linger in the case of chronic infection and progress to atrophic gastritis. The presence of virulence factors in the infecting H. pylori drives the carcinogenesis process. Independent epidemiological and animal studies have confirmed the sequential progression of these precancerous lesions. Particularly long-term follow-up studies estimated a risk of 0.1% for atrophic gastritis/intestinal metaplasia and 6% in case of dysplasia for the long-term development of gastric cancer. With this in mind, a better understanding of the genetic and epigenetic changes associated with progression of the cascade is critical in determining the risk of gastric cancer associated with H. pylori infection. In this review, we will summarize some of the most relevant mechanisms and focus predominantly but not exclusively on the discussion of gene promoter methylation and miRNAs in this context.

Cleaving for growth: threonine aspartase 1--a protease relevant for development and disease

From the beginning of life, proteases are key to organismal development comprising morphogenesis, cellular differentiation, and cell growth. Regulated proteolytic activity is essential for the orchestration of multiple developmental pathways, and defects in protease activity can account for multiple disease patterns. The highly conserved protease threonine aspartase 1 is a member of such developmental proteases and critically involved in the regulation of complex processes, including segmental identity, head morphogenesis, spermatogenesis, and proliferation. Additionally, threonine aspartase 1 is overexpressed in numerous liquid as well as in solid malignancies. Although threonine aspartase 1 is able to cleave the master regulator mixed lineage leukemia protein as well as other regulatory proteins in humans, our knowledge of its detailed pathobiological function and the underlying molecular mechanisms contributing to development and disease is still incomplete. Moreover, neither effective genetic nor chemical inhibitors for this enzyme are available so far precluding the detailed dissection of the pathobiological functions of threonine aspartase 1. Here, we review the current knowledge of the structure-function relationship of threonine aspartase 1 and its mechanistic impact on substrate-mediated coordination of the cell cycle and development. We discuss threonine aspartase 1-mediated effects on cellular transformation and conclude by presenting a short overview of recent interference strategies.

The nuclear fraction of protein kinase CK2 binds to the upstream stimulatory factors (USFs) in the absence of DNA

The functions of the upstream stimulatory factors USF1 and USF2 are, like those of other transcription factors, regulated by reversible phosphorylation. Besides many other kinases also protein kinase CK2 phosphorylates USF1 but not USF2. In a yeast-two-hybrid screen, however, the non-catalytic CK2β subunit of CK2 was identified as a binding partner of USF2. This surprising observation prompted us to investigate the CK2/USF interaction in more detail in the present study. By using immunofluorescence analyses as well as co-immunoprecipitations we found that USF1 and USF2 bound to CK2α and CK2β exclusively in the nucleus, though CK2β and to a minor amount CK2α were also present in the cytoplasm. Furthermore, we found that unlike other substrates the phosphorylation of USF1 required the presence of the regulatory CK2β subunit; the catalytic α-subunit of CK2 alone was not able to phosphorylate USF1. Thus, the correct phosphorylation of USF1 is only guaranteed and strictly controlled in particular by nuclear CK2β. Although the data indicated that a nuclear subfraction of CK2 subunits associated with USF proteins, DNA pull down experiments revealed that the CK2 subunits did not co-localize with DNA bound USF proteins indicating that the USF/CK2 interaction has a pre- or post DNA binding function.

Increased risk of severe fluoropyrimidine-associated toxicity in patients carrying a G to C substitution in the first 28-bp tandem repeat of the thymidylate synthase 2R allele

The fluoropyrimidines act by inhibiting thymidylate synthase (TS). Recent studies have shown that patients' risk of severe fluoropyrimidine-associated toxicity is affected by polymorphisms in the 5'-untranslated region of TYMS, the gene encoding TS. A G>C substitution in the promoter enhancer region of TYMS, rs183205964 (known as the 2RC allele), markedly reduces TS activity in vitro, but its clinical relevance is unknown. We determined rs183205964 in 1605 patients previously enrolled in a prospective multicenter study. Associations between putative low TS expression genotypes (3RC/2RC, 2RG/2RC, and 2RC/2RC) and severe toxicity were investigated using univariable and multivariable logistic regression. Activity of TS and TYMS gene expression were determined in peripheral blood mononuclear cells (PBMCs) of a patient carrying genotype 2RC/2RC and of a control group of healthy individuals. Among 1,605 patients, 28 patients (1.7%) carried the 2RC allele. Twenty patients (1.2%) carried a risk-associated genotype (2RG/2RC, n=13; 3RC/2RC, n=6; and 2RC/2RC, n=1), the eight remaining patients had genotype 3RG/2RC. Early severe toxicity and toxicity-related hospitalization were significantly more frequent in risk-associated genotype carriers (OR 3.0, 95%CI 1.04-8.93, p=0.043 and OR 3.8, 95%CI 1.19-11.9, p=0.024, respectively, in multivariable analysis). The patient with genotype 2RC/2RC was hospitalized twice and had severe febrile neutropenia, diarrhea, and hand-foot syndrome. Baseline TS activity and gene expression in PBMCs of this patient, and a healthy individual with the 2RC allele, were found to be within the normal range. Our study suggests that patients carrying rs183205964 are at strongly increased risk of severe, potentially life-threatening, toxicity when treated with fluoropyrimidines.

Differential epigenetic and transcriptional response of the skeletal muscle carnitine palmitoyltransferase 1B (CPT1B) gene to lipid exposure with obesity

The ability to increase fatty acid oxidation (FAO) in response to dietary lipid is impaired in the skeletal muscle of obese individuals, which is associated with a failure to coordinately upregulate genes involved with FAO. While the molecular mechanisms contributing to this metabolic inflexibility are not evident, a possible candidate is carnitine palmitoyltransferase-1B (CPT1B), which is a rate-limiting step in FAO. The present study was undertaken to determine if the differential response of skeletal muscle CPT1B gene transcription to lipid between lean and severely obese subjects is linked to epigenetic modifications (DNA methylation and histone acetylation) that impact transcriptional activation. In primary human skeletal muscle cultures the expression of CPT1B was blunted in severely obese women compared with their lean counterparts in response to lipid, which was accompanied by changes in CpG methylation, H3/H4 histone acetylation, and peroxisome proliferator-activated receptor-δ and hepatocyte nuclear factor 4α transcription factor occupancy at the CPT1B promoter. Methylation of specific CpG sites in the CPT1B promoter that correlated with CPT1B transcript level blocked the binding of the transcription factor upstream stimulatory factor, suggesting a potential causal mechanism. These findings indicate that epigenetic modifications may play important roles in the regulation of CPT1B in response to a physiologically relevant lipid mixture in human skeletal muscle, a major site of fatty acid catabolism, and that differential DNA methylation may underlie the depressed expression of CPT1B in response to lipid, contributing to the metabolic inflexibility associated with severe obesity.

Three decades of low-dose methotrexate in rheumatoid arthritis: can we predict toxicity?

Methotrexate (MTX) is the anchor disease-modifying antirheumatic drug (DMARD) in rheumatoid arthritis (RA) treatment. It is used in monotherapy and/or in combination with other synthetic or biological DMARDs, and is known to have the best cost-effectiveness and efficacy/toxicity ratios. However, toxicity is still a concern, with a significant proportion of patients interrupting long-term treatment due to the occurrence of MTX-related adverse drug reactions (ADRs), which are the main cause of drug withdrawal. Despite the extensive accumulated experience in the last three decades, it is still impossible in routine clinical practice to identify patients prone to develop MTX toxicity. While clinical and biological variables, including folate supplementation, partially help to minimize MTX-related ADRs, the advent of pharmacogenomics could provide further insight into risk stratification and help to optimize drug monitoring and long-term retention. In this paper, we aimed to review and summarize current data on low-dose MTX-associated toxicity, its prevention and predictors, keeping in mind practical RA clinical care.

The rs2516839 Polymorphism of the USF1 Gene May Modulate Serum Triglyceride Levels in Response to Cigarette Smoking

Single nucleotide polymorphisms (SNPs) of the USF1 gene (upstream stimulatory factor 1) influence plasma lipid levels. This study aims to determine whether USF1 SNPs interact with traditional risk factors of atherosclerosis to increase coronary artery disease (CAD) risk. In the present study serum lipid levels and USF1 gene polymorphisms (rs2516839 and rs3737787) were determined in 470 subjects: 235 patients with premature CAD and 235 controls. A trend of increasing triglycerides (TG) levels in relation to the C allele dose of rs2516839 SNP was observed. The synergistic effect of cigarette smoking and C allele carrier state on CAD risk was also found (SIM = 2.69, p = 0.015). TG levels differentiated significantly particular genotypes in smokers (1.53 mmol/L for TT, 1.80 mmol/L for CT and 2.27 mmol/L for CC subjects). In contrast, these differences were not observed in the non-smokers subgroup (1.57 mmol/L for TT, 1.46 mmol/L for CT and 1.49 mmol/L for CC subjects). In conclusion, the rs2516839 polymorphism may modulate serum triglyceride levels in response to cigarette smoking. Carriers of the C allele seem to be particularly at risk of CAD, when exposed to cigarette smoking.

The basic helix-loop-helix/leucine zipper transcription factor USF2 integrates serum-induced PAI-1 expression and keratinocyte growth

Plasminogen activator inhibitor type-1 (PAI-1), a major regulator of the plasmin-dependent pericellular proteolytic cascade, is prominently expressed during the tissue response to injury although the factors that impact PAI-1 induction and their role in the repair process are unclear. Kinetic modeling using established biomarkers of cell cycle transit (c-MYC; cyclin D1; cyclin A) in synchronized human (HaCaT) keratinocytes, and previous cytometric assessments, indicated that PAI-1 transcription occurred early after serum-stimulation of quiescent (G0) cells and prior to G1 entry. It was established previously that differential residence of USF family members (USF1→USF2 switch) at the PE2 region E box (CACGTG) characterized the G0  → G1 transition period and the transcriptional status of the PAI-1 gene. A consensus PE2 E box motif (5'-CACGTG-3') at nucleotides -566 to -561 was required for USF/E box interactions and serum-dependent PAI-1 transcription. Site-directed CG → AT substitution at the two central nucleotides inhibited formation of USF/probe complexes and PAI-1 promoter-driven reporter expression. A dominant-negative USF (A-USF) construct or double-stranded PE2 "decoy" attenuated serum- and TGF-β1-stimulated PAI-1 synthesis. Tet-Off induction of an A-USF insert reduced both PAI-1 and PAI-2 transcripts while increasing the fraction of Ki-67(+) cells. Conversely, overexpression of USF2 or adenoviral-delivery of a PAI-1 vector inhibited HaCaT colony expansion indicating that the USF1 → USF2 transition and subsequent PAI-1 transcription are critical events in the epithelial go-or-grow response. Collectively, these data suggest that USF2, and its target gene PAI-1, regulate serum-stimulated keratinocyte growth, and likely the cadence of cell cycle progression in replicatively competent cells as part of the injury repair program.

Role of upstream stimulatory factor 2 in diabetic nephropathy

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease (ESRD). About 20%-30% of people with type 1 and type 2 diabetes develop DN. DN is characterized by both glomerulosclerosis with thickening of the glomerular basement membrane and mesangial matrix expansion, and tubulointerstitial fibrosis. Hyperglycemia and the activation of the intra-renal renin-angiotensin system (RAS) in diabetes have been suggested to play a critical role in the pathogenesis of DN. However, the mechanisms are not well known. Studies from our laboratory demonstrated that the transcription factor-upstream stimulatory factor 2 (USF2) is an important regulator of DN. Moreover, the renin gene is a downstream target of USF2. Importantly, USF2 transgenic (Tg) mice demonstrate a specific increase in renal renin expression and angiotensin II (AngII) levels in kidney and exhibit increased urinary albumin excretion and extracellular matrix deposition in glomeruli, supporting a role for USF2 in the development of diabetic nephropathy. In this review, we summarize our findings of the mechanisms by which diabetes regulates USF2 in kidney cells and its role in regulation of renal renin-angiotensin system and the development of diabetic nephropathy.

Polymorphisms related to ORMDL3 are associated with asthma susceptibility, alterations in transcriptional regulation of ORMDL3, and changes in TH2 cytokine levels

BACKGROUND

Chromosome 17q21, harboring the orosomucoid 1-like 3 (ORMDL3) gene, has been consistently associated with childhood asthma in genome-wide association studies.

OBJECTIVE

We investigated genetic variants in and around ORMDL3 that can change the function of ORMDL3 and thus contribute to asthma susceptibility.

METHODS

We performed haplotype analyses and fine mapping of the ORMDL3 locus in a cross-sectional (International Study of Asthma and Allergies in Childhood Phase II, n = 3557 total subjects, n = 281 asthmatic patients) and case-control (Multicenter Asthma Genetics in Childhood Study/International Study of Asthma and Allergies in Childhood Phase II, n = 1446 total subjects, n = 763 asthmatic patients) data set to identify putative causal single nucleotide polymorphisms (SNPs) in the locus. Top asthma-associated polymorphisms were analyzed for allele-specific effects on transcription factor binding and promoter activity in vitro and gene expression in PBMCs after stimulation ex vivo.

RESULTS

Two haplotypes (H1 and H2) were significantly associated with asthma in the cross-sectional (P = 9.9 × 10(-5) and P = .0035, respectively) and case-control (P = 3.15 × 10(-8) and P = .0021, respectively) populations. Polymorphisms rs8076131 and rs4065275 were identified to drive these effects. For rs4065275, a quantitative difference in transcription factor binding was found, whereas for rs8076131, changes in upstream stimulatory factor 1 and 2 transcription factor binding were observed in vitro by using different cell lines and PBMCs. This might contribute to detected alterations in luciferase activity paralleled with changes in ORMDL3 gene expression and IL-4 and IL-13 cytokine levels ex vivo in response to innate and adaptive stimuli in an allele-specific manner. Both SNPs were in strong linkage disequilibrium with asthma-associated 17q21 SNPs previously related to altered ORMDL3 gene expression.

CONCLUSION

Polymorphisms in a putative promoter region of ORMDL3, which are associated with childhood asthma, alter transcriptional regulation of ORMDL3, correlate with changes in TH2 cytokines levels, and therefore might contribute to the childhood asthma susceptibility signal from 17q21.

Quercetin-3-O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranoside suppresses melanin synthesis by augmenting p38 MAPK and CREB signaling pathways and subsequent cAMP down-regulation in murine melanoma cells

In this study, the effect of purified quercetin-3-O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosid (QCGG) on melanogenesis was investigated. QCGG was isolated from the calyx of a traditional Korean medicinal herb, Persimmon (Diospyros kaki). The hypopigmentation effects of QCGG were determined by examination of cellular melanin contents, tyrosinase activity assay, cAMP assay, and Western blotting of α-MSH-stimulated B16F10 mouse melanoma cells. Our results showed that QCGG inhibited both melanin synthesis and tyrosinase activity in a concentration-dependent manner as well as significantly reduced the expression of melanogenic proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1, tyrosinase-related protein-2, and tyrosinase. Moreover, QCGG inhibited intracellular cAMP levels, cAMP response element-binding protein (CREB), and p38 MAPK expression in α-MSH-stimulated B16F10 cells. Taken together, the suppressive effects of QCGG on melanogenesis may involve down-regulation of MITF and its downstream signaling pathway via phosphorylation of p38 MAPK and CREB along with reduced cAMP levels. These results indicate that QCGG reduced melanin synthesis by reducing expression of tyrosine and tyrosine-related proteins via extracellular signal-related protein kinase (ERK) activation, followed by down-regulation of CREB, p38, and MITF.

Protein kinases as switches for the function of upstream stimulatory factors: implications for tissue injury and cancer

The upstream stimulatory factors (USFs) are regulators of important cellular processes. Both USF1 and USF2 are supposed to have major roles in metabolism, tissue protection and tumor development. However, the knowledge about the mechanisms that control the function of USFs, in particular in tissue protection and cancer, is limited. Phosphorylation is a versatile tool to regulate protein functions. Thereby, phosphorylation can positively or negatively affect different aspects of transcription factor function including protein stability, protein-protein interaction, cellular localization, or DNA binding. The present review aims to summarize the current knowledge about the regulation of USFs by direct phosphorylation and the consequences for USF functions in tissue protection and cancer.

Requirement of the transcription factor USF1 in bovine oocyte and early embryonic development

Upstream stimulating factor 1 (USF1) is a basic helix-loop-helix transcription factor that specifically binds to E-box DNA motifs, known cis-elements of key oocyte expressed genes essential for oocyte and early embryonic development. However, the functional and regulatory role of USF1 in bovine oocyte and embryo development is not understood. In this study, we demonstrated that USF1 mRNA is maternal in origin and expressed in a stage specific manner during the course of oocyte maturation and preimplantation embryonic development. Immunocytochemical analysis showed detectable USF1 protein during oocyte maturation and early embryonic development with increased abundance at 8-16-cell stage of embryo development, suggesting a potential role in embryonic genome activation. Knockdown of USF1 in germinal vesicle stage oocytes did not affect meiotic maturation or cumulus expansion, but caused significant changes in mRNA abundance for genes associated with oocyte developmental competence. Furthermore, siRNA-mediated depletion of USF1 in presumptive zygote stage embryos demonstrated that USF1 is required for early embryonic development to the blastocyst stage. A similar (USF2) yet unique (TWIST2) expression pattern during oocyte and early embryonic development for related E-box binding transcription factors known to cooperatively bind USF1 implies a potential link to USF1 action. This study demonstrates that USF1 is a maternally derived transcription factor required for bovine early embryonic development, which also functions in regulation of JY1, GDF9, and FST genes associated with oocyte competence.

Role of key TYMS polymorphisms on methotrexate therapeutic outcome in portuguese rheumatoid arthritis patients

BACKGROUND

Therapeutic outcome of rheumatoid arthritis (RA) patients treated with methotrexate (MTX) can be modulated by thymidylate synthase (TS) levels, which may be altered by genetic polymorphisms in TS gene (TYMS). This study aims to elucidate the influence of TYMS polymorphisms in MTX therapeutic outcome (regarding both clinical response and toxicity) in Portuguese RA patients.

METHODS

Clinicopathological data from 233 Caucasian RA patients treated with MTX were collected, outcomes were defined and patients were genotyped for the following TYMS polymorphisms: 1) 28 base pairs (bp) variable number tandem repeat (rs34743033); 2) single nucleotide polymorphism C>G (rs2853542); and 3) 6 bp sequence deletion (1494del6, rs34489327). Chi-square and binary logistic regression analyses were performed, using genotype and haplotype-based approaches.

RESULTS

Considering TYMS genotypes, 3R3R (p = 0.005, OR = 2.34), 3RC3RG (p = 0.016, OR = 3.52) and 6bp- carriers (p = 0.011, OR = 1.96) were associated with non-response to MTX. Multivariate analysis confirmed the increased risk for non-response to MTX in 6bp- carriers (p = 0.016, OR = 2.74). Data demonstrated that TYMS polymorphisms were in linkage disequilibrium (p<0.00001). Haplotype multivariate analysis revealed that haplotypes harboring both 3R and 6bp- alleles were associated with non-response to MTX. Regarding MTX-related toxicity, no statistically significant differences were observed in relation to TYMS genotypes and haplotypes.

CONCLUSION

Our study reveals that TYMS polymorphisms could be important to help predicting clinical response to MTX in RA patients. Despite the potential of these findings, translation into clinical practice needs larger studies to confirm these evidences.

Pdx1 and USF transcription factors co-ordinately regulate Alx3 gene expression in pancreatic β-cells

We investigated the transcriptional mechanisms regulating the expression of Alx3 in pancreatic islets. We found that the transcriptional transactivation of Alx3 in β-cells requires the co-operation of the islet-specific homeoprotein Pdx1 with the transcription factors USF1 and USF2.

GSK3β-dependent phosphorylation alters DNA binding, transactivity and half-life of the transcription factor USF2

The upstream stimulatory factor 2 (USF2) is a regulator of important cellular processes and is supposed to have also a role during tumor development. However, the knowledge about the mechanisms that control the function of USF2 is limited. The data of the current study show that USF2 function is regulated by phosphorylation and identified GSK3β as an USF2-phosphorylating kinase. The phosphorylation sites within USF2 could be mapped to serine 155 and threonine 230. In silico analyses of the 3-dimensional structure revealed that phosphorylation of USF2 by GSK3β converts it to a more open conformation which may influence transactivity, DNA binding and target gene expression. Indeed, experiments with GSK-3β-deficient cells revealed that USF2 transactivity, DNA binding and target gene expression were reduced upon lack of GSK3β. Further, experiments with USF2 variants mimicking GSK3β phosphorylated USF2 in GSK3β-deficient cells showed that phosphorylation of USF2 by GSK3β did not affect cell proliferation but increased cell migration. Together, this study reports a new mechanism by which USF2 may contribute to cancerogenesis.

The upstream stimulatory factor USF1 is regulated by protein kinase CK2 phosphorylation

The upstream stimulatory factors 1 (USF1) and 2 (USF2) are transcription factors which bind to E-box motifs of various promoters regulating a variety of different cellular processes. Only little is known about the regulation of USFs. Here, we identified protein kinase CK2 as an enzyme that phosphorylates USF1 but not USF2. Using deletion mutants and point mutants we were able to identify threonine 100 as the major phosphorylation site for CK2. It is well known that USF1 and USF2 form hetero-dimers. Binding studies revealed that the inhibition of CK2 kinase activity by a specific inhibitor enhanced binding of USF1 to USF2. Furthermore, transactivation studies showed that the inhibition of CK2 phosphorylation of USF1 stimulated transcription from the glucokinase promoter as well as the fatty acid synthetase promoter but not from the heme oxygenase-1 promoter. Thus, we have shown for the first time that CK2 phosphorylation of USF1 modulates two functionally important properties of USF1, namely hetero-dimerization and transactivation.

Cathepsin B: multiple roles in cancer

Proteases, including intracellular proteases, play roles at many different stages of malignant progression. Our focus here is cathepsin B, a lysosomal cysteine cathepsin. High levels of cathepsin B are found in a wide variety of human cancers, levels that often induce secretion and association of cathepsin B with the tumor cell membrane. In experimental models, such as transgenic models of murine pancreatic and mammary carcinomas, causal roles for cathepsin B have been demonstrated in initiation, growth/tumor cell proliferation, angiogenesis, invasion, and metastasis. Tumor growth in transgenic models is promoted by cathepsin B in tumor-associated cells, for example, tumor-associated macrophages, as well as in tumor cells. In transgenic models, the absence of cathepsin B has been associated with enhanced apoptosis, yet cathepsin B also has been shown to contribute to apoptosis. Cathepsin B is part of a proteolytic pathway identified in xenograft models of human glioma; targeting only cathepsin B in these tumors is less effective than targeting cathepsin B in combination with other proteases or protease receptors. Understanding the mechanisms responsible for increased expression of cathepsin B in tumors and association of cathepsin B with tumor cell membranes is needed to determine whether targeting cathepsin B could be of therapeutic benefit.

Suppression of adipogenesis by valproic acid through repression of USF1-activated fatty acid synthesis in adipocytes

Valproic acid suppresses the accumulation of the intracellular lipids through suppression of fatty acid synthesis via repression of USF1-mediated expression of the fatty acid synthase gene in adipocytes.

Dissecting the function of the adult β-globin downstream promoter region using an artificial zinc finger DNA-binding domain

Developmental stage-specific expression of the β-type globin genes is regulated by many cis- and trans-acting components. The adult β-globin gene contains an E-box located 60 bp downstream of the transcription start site that has been shown to bind transcription factor upstream stimulatory factor (USF) and to contribute to efficient in vitro transcription. We expressed an artificial zinc finger DNA-binding domain (ZF-DBD) targeting this site (+60 ZF-DBD) in murine erythroleukemia cells. Expression of the +60 ZF-DBD reduced the recruitment and elongation of RNA polymerase II (Pol II) at the adult β-globin gene and at the same time increased the binding of Pol II at locus control region (LCR) element HS2, suggesting that Pol II is transferred from the LCR to the globin gene promoters. Expression of the +60 ZF-DBD also reduced the frequency of interactions between the LCR and the adult β-globin promoter. ChIP-exonuclease-sequencing revealed that the +60ZF-DBD was targeted to the adult β-globin downstream promoter and that the binding of the ZF-DBD caused alterations in the association of USF2 containing protein complexes. The data demonstrate that targeting a ZF-DBD to the adult β-globin downstream promoter region interferes with the LCR-mediated recruitment and activity of Pol II.

Expression, regulation, and promoter activation of vanin-2 (VNN2) in bovine follicles prior to ovulation

Vanin-2 (VNN2) is known to be involved in inflammation and leukocyte migration, but its regulation in follicles remains unknown. The objectives of this work were to study the regulation of VNN2 transcripts in bovine follicles prior to ovulation and to characterize the control of its expression in bovine granulosa cells. VNN2 expression was studied using total RNA extracted from granulosa cells of small follicles (2-4 mm in diameter), dominant follicles obtained on Day 5 of the estrous cycle, ovulatory follicles obtained 0-24 h after human chorionic gonadotropin (hCG), and corpora lutea on Day 5 of the cycle. The results from RT-PCR analyses showed that levels of VNN2 mRNA were high in ovulatory follicles 24 h post-hCG but low in the other tissues. In ovulatory follicles, levels of VNN2 mRNA were low at 0 h but significantly up-regulated 12-24 h post-hCG. To determine factors controlling VNN2 gene expression, established primary cultures of granulosa cells isolated from bovine dominant follicles were used. Treatment with forskolin elevated VNN2 mRNA expression as observed in vivo. Mutation studies identified the minimal region conferring basal and forskolin-stimulated VNN2 promoter activities, which were dependent on chicken ovalbumin upstream promoter-transcription factor (COUP-TF), GATA, and Ebox cis-elements. Electrophoretic mobility shift assays identified COUP-TF, GATA4, and upstream stimulating factor proteins as key factors interacting with these elements. Chromatin immunoprecipitation assays confirmed basal and forskolin-induced interactions between these proteins and the VNN2 promoter in bovine granulosa cell cultures. VNN2 promoter activity and mRNA expression were markedly stimulated by forskolin and overexpression of the catalytic subunit of PKA, but inhibited by PKA and ERK1/2 inhibitors. Collectively, the findings from this study describe for the first time the gonadotropin/forskolin-dependent up-regulation of VNN2 transcripts in granulosa cells of preovulatory follicles and provide insights into some of the molecular bases of VNN2 gene expression in follicular cells.

Enhancement of the p38 MAPK and PKA signaling pathways is associated with the pro-melanogenic activity of Interleukin 33 in primary melanocytes

BACKGROUND

Interleukin-33 (IL-33) was recently recognized as a member of the IL-1 cytokine family. The triggers no matter environmental or endogenous that provoke IL-33 cellular release may be associated with inflammation, infection or tissue damage. However, to date, the regulatory role of IL-33 in the control of melanogenesis has not been elucidated.

OBJECTIVE

The present study was designed to investigate the effect of IL-33 on melanogenesis and to explore its underlying mechanisms.

METHODS

Melanocytes were exposed to IL-33. Then cell viabilities were measured by MTT assay. The improving activities of IL-33 were examined by melanin synthesis, tyrosinase (TYR) activity assay. The expressions of relative proteins were assessed by Western blotting.

RESULTS

IL-33 increased the TYR activity and melanin content in a dosage-dependent manner at concentrations of 1-10ng/ml. Treatment with 10ng/ml of IL-33 enhanced the expression of microphthalmia-associated transcription factor (MITF), TYR, tyrosinase-related protein 1 (TRP-1) and dopachrome tautomerase (DCT) in normal human foreskin-derived epidermal melanocytes (NHEM). Furthermore, IL-33 could remarkably promote the phosphorylation levels of p38 mitogen-activated protein kinases (MAPKs) and cyclic AMP-responsive element-binding protein (CREB). This pro-melanogenic effect could be partially reversed by the pre-treatment with the special p38 MAPK inhibitor, SB203580, and protein kinase A (PKA) inhibitor, H89.

CONCLUSIONS

Our results collectively indicated that IL-33 improved melanin biosynthesis in NHEM. This function might be attributed to the fact that IL-33 stimulates the phosphorylation of p38 MAPK and CREB, increases the TYR, TRP-1 and DCT expression through MITF, finally resulting in the augment of melanogenesis.

Global DNA methylation remodeling accompanies CD8 T cell effector function

The differentiation of CD8 T cells in response to acute infection results in the acquisition of hallmark phenotypic effector functions; however, the epigenetic mechanisms that program this differentiation process on a genome-wide scale are largely unknown. In this article, we report the DNA methylomes of Ag-specific naive and day-8 effector CD8 T cells following acute lymphocytic choriomeningitis virus infection. During effector CD8 T cell differentiation, DNA methylation was remodeled such that changes in DNA methylation at gene promoter regions correlated negatively with gene expression. Importantly, differentially methylated regions were enriched at cis-elements, including enhancers active in naive T cells. Differentially methylated regions were associated with cell type-specific transcription factor binding sites, and these transcription factors clustered into modules that define networks targeted by epigenetic regulation and control of effector CD8 T cell function. Changes in the DNA methylation profile following CD8 T cell activation revealed numerous cellular processes, cis-elements, and transcription factor networks targeted by DNA methylation. Together, the results demonstrated that DNA methylation remodeling accompanies the acquisition of the CD8 T cell effector phenotype and repression of the naive cell state. Therefore, these data provide the framework for an epigenetic mechanism that is required for effector CD8 T cell differentiation and adaptive immune responses.

STAT3 or USF2 contributes to HIF target gene specificity

The HIF1- and HIF2-mediated transcriptional responses play critical roles in solid tumor progression. Despite significant similarities, including their binding to promoters of both HIF1 and HIF2 target genes, HIF1 and HIF2 proteins activate unique subsets of target genes under hypoxia. The mechanism for HIF target gene specificity has remained unclear. Using siRNA or inhibitor, we previously reported that STAT3 or USF2 is specifically required for activation of endogenous HIF1 or HIF2 target genes. In this study, using reporter gene assays and chromatin immuno-precipitation, we find that STAT3 or USF2 exhibits specific binding to the promoters of HIF1 or HIF2 target genes respectively even when over-expressed. Functionally, HIF1α interacts with STAT3 to activate HIF1 target gene promoters in a HIF1α HLH/PAS and N-TAD dependent manner while HIF2α interacts with USF2 to activate HIF2 target gene promoters in a HIF2α N-TAD dependent manner. Physically, HIF1α HLH and PAS domains are required for its interaction with STAT3 while both N- and C-TADs of HIF2α are involved in physical interaction with USF2. Importantly, addition of functional USF2 binding sites into a HIF1 target gene promoter increases the basal activity of the promoter as well as its response to HIF2+USF2 activation while replacing HIF binding site with HBS from a HIF2 target gene does not change the specificity of the reporter gene. Importantly, RNA Pol II on HIF1 or HIF2 target genes is primarily associated with HIF1α or HIF2α in a STAT3 or USF2 dependent manner. Thus, we demonstrate here for the first time that HIF target gene specificity is achieved by HIF transcription partners that are required for HIF target gene activation, exhibit specific binding to the promoters of HIF1 or HIF2 target genes and selectively interact with HIF1α or HIF2α protein.

Molecular characterization and transcriptional regulation of a disintegrin and metalloproteinase with thrombospondin motif 1 (ADAMTS1) in bovine preovulatory follicles

The ovulatory process involves a complex remodeling of the extracellular matrix during which a desintegrin and metalloproteinase with thrombospondin motif 1 (ADAMTS1) is thought to play a key role, but its transcriptional regulation in bovine follicles remains largely unknown. The objectives of this study were to characterize the regulation of ADAMTS1 in bovine follicles before ovulation and to determine its transcriptional control in bovine granulosa cells. Regulation of ADAMTS1 was assessed using total RNA isolated from bovine preovulatory follicles obtained at various times after human chorionic gonadotropin treatment. Results from RT-PCR analyses showed that levels of ADAMTS1 mRNA were very low at 0 hours but increased at 6 to 24 hours after human chorionic gonadotropin in granulosa cells. To determine the regulatory mechanisms controlling ADAMTS1 gene expression in vitro, primary cultures of bovine granulosa cells were established, and treatment with forskolin up-regulated ADAMTS1 mRNA levels. Promoter activity assays, 5'-deletion, and site-directed mutagenesis identified a minimal region conferring full-length basal and forskolin-stimulated ADAMTS1 promoter activities, with both being dependent on Ebox cis-acting elements. EMSAs revealed upstream stimulating factor (USF) proteins as key trans-activating factors interacting with Ebox. Chromatin immunoprecipitation assays confirmed such interactions between USF and Ebox in vivo, and USF binding to Ebox elements was increased by forskolin treatment. ADAMTS1 promoter activity and mRNA expression were increased by forskolin and overexpression of the catalytic subunit of protein kinase A, but not by cotreatment with inhibitors of protein kinase A, ERK1/2, and epidermal growth factor receptor signaling pathways. Furthermore, treatment with a soluble epidermal growth factor induced ADAMTS1 mRNA expression in granulosa cells. Collectively, results from this study describe the gonadotropin/forskolin-dependent up-regulation of ADAMTS1 mRNA in granulosa cells of bovine preovulatory follicles in vivo and in vitro and identify for the first time some of the molecular mechanisms responsible for ADAMTS1 promoter activation in follicular cells of a large monoovulatory species.

Current approaches for TYMS polymorphisms and their importance in molecular epidemiology and pharmacogenetics

TS is critical for providing the requisite nucleotide precursors in order to maintain DNA synthesis and repair. Furthermore, it is an important target for several drugs such as 5-fluorouracil and methotrexate. However, several mechanisms of resistance to TS inhibitors have been explained as linked to TYMS overexpression. Some authors have described the relationship between genetic polymorphisms on TYMS, in particular rs34743033, rs2853542 and rs34489327, with the development of several diseases and with the clinical response to drug therapy and/or survival. Nevertheless, the obtained results described in the literature are controversial, which has lead to a search strategy to understand the impact of these polymorphisms on molecular epidemiology and pharmacogenetics. With the progress of these scientific areas, early identification of individuals at risk of disease along with improvement in the prediction of patients’ outcome will offer a powerful tool for the translation of TYMS polymorphisms into clinical practice and individualization of treatments.

Molecular characterization, expression patterns, and association analysis with carcass traits of porcine USF1 gene

The upstream stimulatory factor 1 (USF1) is a transcription factor controlling expression of several genes involved in lipid and glucose homeostasis. In this study, two isoforms of the porcine USF1 gene were detected by reverse transcription polymerase chain reaction (RT-PCR), termed USF1 wild-type (wt) and USF1/CD, both of them contain a helix-loop-helix leucine zipper (HLH-LZ) conserved domain. Tissue distribution analysis showed that the two transcripts of porcine USF1 gene were ubiquitously expressed in all tested tissues, except for heart. Moreover, we found that a single nucleotide polymorphism (SNP, C/T) in intron 10 was significantly associated with ratio of lean to fat (P < 0.05), dress percentage (P < 0.05), average backfat thickness (P < 0.05), loin eye width (P < 0.05), lean meat percentage (P < 0.01), loin eye height (P < 0.01), and loin eye area (P < 0.01). This result suggests that porcine USF1 gene may be a candidate gene of meat production trait.