Positive and negative regulation of transcription in vitro: enhancer-binding protein AP-2 is inhibited by SV40 T antigen

Structural basis for specific DNA sequence motif recognition by the TFAP2 transcription factors

The TFAP2 family regulates gene expression during differentiation, development, and organogenesis, and includes five homologs in humans. They all possess a highly conserved DNA binding domain (DBD) followed by a helix-span-helix (HSH) domain. The DBD-HSH tandem domain specifically binds to a GCC(N3)GGC consensus sequence, but the precise recognition mechanisms remain unclear. Here, we found that TFAP2 preferred binding to the GCC(N3)GGC sequence, and the pseudo-palindromic GCC and GGC motifs and the length of the central spacer between the two motifs determined their binding specificity. Structural studies revealed that the two flat amphipathic α-helical HSH domains of TFAP2A stacked with each other to form a dimer via hydrophobic interactions, while the stabilized loops from both DBD domains inserted into two neighboring major grooves of the DNA duplex to form base-specific interactions. This specific DNA binding mechanism controlled the length of the central spacer and determined the DNA sequence specificity of TFAP2. Mutations of the TFAP2 proteins are implicated in various diseases. We illustrated that reduction or disruption of the DNA binding ability of the TFAP2 proteins is the primary cause of TFAP2 mutation-associated diseases. Thus, our findings also offer valuable insights into the pathogenesis of disease-associated mutations in TFAP2 proteins.

Transcription factor activating enhancer-binding protein 2B expression correlates with invasiveness and prognosis of extramammary Paget's disease

BACKGROUND

Extramammary Paget's disease (EMPD) is a slowly advancing malignancy that sometimes progresses to the invasion of the dermis, systemic metastases, and death. Although there have been reports that dermal invasion is associated with poor prognosis, no molecular markers of this invasion have been identified thus far. The aim of this study was to identify key molecules for predicting the risk of EMPD dermis invasion.

METHOD

We performed microarray screening for three cases of in-situ EMPDs, three cases of invasive EMPDs, and three cases of normal epidermis. We identified a molecule that exhibited a stepwise increase in expression. Further, we analyzed 47 cases of EMPD using immunohistochemical staining (IHC) and examined the correlated clinicopathological findings, including prognosis.

RESULT

We examined molecules that showed stepwise differences with invasion. We focused on transcription factor activating enhancer-binding protein 2 B (TFAP2B). Of the 47 EMPD patients, 38 (80.9 %) and 9 (19.1 %) had low and high TFAP2B expression, respectively. TFAP2B expression was significantly correlated with invasion into the dermis, mass formation, and preoperative lymph node metastasis (p = 0.001, 0.042, and 0.033, respectively). The cumulative postoperative recurrence-free rate in the TFAP2B-high expression group was significantly lower than that in the TFAP2B-low expression group (P < 0.001). In univariate analysis of recurrence-free survival, TFAP2B expression was found to be a significant factor (p = 0.006).

CONCLUSION

The expression of TFAP2B, which was comprehensively found by microarray screening, may correlate with the invasiveness of EMPD and may be an unfavorable prognostic factor.

The oncogenic role of TFAP2A in bladder urothelial carcinoma via a novel long noncoding RNA TPRG1-AS1/DNMT3A/CRTAC1 axis

BACKGROUND

Overexpression of TFAP2A has been linked to increased lymph node metastasis in basal-squamous bladder cancer. However, its downstream targets in bladder urothelial carcinoma (BLCA), the most malignant cancer of the urinary tract, remain unclear. In the current study, we aim to explore the function and mechanism of TFAP2A in BLCA.

METHODS

TFAP2A expression and the prognostic significance in BLCA was analyzed using TCGA and GTEX projects. TFAP2A was knocked-down in BLCA cells to study its impact on glucose uptake, lactate and ATP production, expression of HK2, and the number of vascular meshes formed by HUVEC. The target long noncoding RNAs (lncRNAs) of TFAP2A were predicted by bioinformatics tools, followed by ChIP-qPCR and luciferase assays. The downstream targets of TPRG1-AS1 were analyzed by microarray analysis. Rescue experiments were conducted for validation.

RESULTS

TFAP2A upregulation in BLCA predicted dismal survival of patients. Loss of TFAP2A inhibited glycolysis (as evidenced by reduced glucose uptake, lactate, ATP production, and the expression of HK2) and angiogenesis (decreased number of vascular meshes formed by HUVEC). TFAP2A promoted the transcription of TPRG1-AS1. TPRG1-AS1 reversed the inhibitory effect of TFAP2A knockdown on glycolysis and angiogenesis in BLCA cells. TPRG1-AS1 inhibited the transcription of CRTAC1 by recruiting a DNA methyltransferase to the promoter of CRTAC1 and increasing the DNA methylation of its promoter. CRTAC1 inhibited glycolysis and angiogenesis in BLCA cells. TFAP2A silencing curbed tumor growth in vivo via the TPRG1-AS1/CRTAC1 axis.

CONCLUSION

TFAP2A reduces CRTAC1 expression by promoting TPRG1-AS1 transcription, thereby expediting BLCA glycolysis and angiogenesis.

Overexpression of Tfap2a in Mouse Oocytes Impaired Spindle and Chromosome Organization

Transcription factor AP-2-alpha (Tfap2a) is an important sequence-specific DNA-binding protein that can regulate the transcription of multiple genes by collaborating with inducible viral and cellular enhancer elements. In this experiment, the expression, localization, and functions of Tfap2a were investigated in mouse oocytes during maturation. Overexpression via microinjection of Myc-Tfap2a mRNA into the ooplasm, immunofluorescence, and immunoblotting were used to study the role of Tfap2a in mouse oocyte meiosis. According to our results, Tfap2a plays a vital role in mouse oocyte maturation. Levels of Tfap2a in GV oocytes of mice suffering from type 2 diabetes increased considerably. Tfap2a was distributed in both the ooplasm and nucleoplasm, and its level gradually increased as meiosis resumption progressed. The overexpression of Tfap2a loosened the chromatin, accelerated germinal vesicle breakdown (GVBD), and blocked the first polar body extrusion 14 h after maturation in vitro. The width of the metaphase plate at metaphase I stage increased, and the spindle and chromosome organization at metaphase II stage were disrupted in the oocytes by overexpressed Tfap2a. Furthermore, Tfap2a overexpression dramatically boosted the expression of p300 in mouse GV oocytes. Additionally, the levels of pan histone lysine acetylation (Pan Kac), histone H4 lysine 12 acetylation (H4K12ac), and H4 lysine 16 acetylation (H4K16ac), as well as pan histone lysine lactylation (Pan Kla), histone H3 lysine18 lactylation (H3K18la), and H4 lysine12 lactylation (H4K12la), were all increased in GV oocytes after Tfap2a overexpression. Collectively, Tfap2a overexpression upregulated p300, increased the levels of histone acetylation and lactylation, impeded spindle assembly and chromosome alignment, and ultimately hindered mouse oocyte meiosis.

The regulatory role of AP-2β in monoaminergic neurotransmitter systems: insights on its signalling pathway, linked disorders and theragnostic potential

Monoaminergic neurotransmitter systems play a central role in neuronal function and behaviour. Dysregulation of these systems gives rise to neuropsychiatric and neurodegenerative disorders with high prevalence and societal burden, collectively termed monoamine neurotransmitter disorders (MNDs). Despite extensive research, the transcriptional regulation of monoaminergic neurotransmitter systems is not fully explored. Interestingly, certain drugs that act on these systems have been shown to modulate central levels of the transcription factor AP-2 beta (AP-2β, gene: TFAP2Β). AP-2β regulates multiple key genes within these systems and thereby its levels correlate with monoamine neurotransmitters measures; yet, its signalling pathways are not well understood. Moreover, although dysregulation of TFAP2Β has been associated with MNDs, the underlying mechanisms for these associations remain elusive. In this context, this review addresses AP-2β, considering its basic structural aspects, regulation and signalling pathways in the controlling of monoaminergic neurotransmitter systems, and possible mechanisms underpinning associated MNDS. It also underscores the significance of AP-2β as a potential diagnostic biomarker and its potential and limitations as a therapeutic target for specific MNDs as well as possible pharmaceutical interventions for targeting it. In essence, this review emphasizes the role of AP-2β as a key regulator of the monoaminergic neurotransmitter systems and its importance for understanding the pathogenesis and improving the management of MNDs.

Transcription factor AP-2beta in development, differentiation and tumorigenesis

To date, the AP-2 family of transcription factors comprises five members. Transcription factor AP-2beta (TFAP2B)/AP-2β was first described in 1995. Several studies indicate a critical role of AP-2β in the development of tissues and organs of ectodermal, neuroectodermal and also mesodermal origin. Germline mutation of TFAP2B is known to cause the Char syndrome, an autosomal dominant disorder characterized by facial dysmorphism, patent ductus arteriosus and anatomical abnormalities of the fifth digit. Furthermore, single-nucleotide polymorphisms in TFAP2B were linked to obesity and specific personality traits. In neoplasias, AP-2β was first described in alveolar rhabdomyosarcoma. Immunohistochemical staining of AP-2β is a recommended ancillary test for the histopathological diagnosis of this uncommon childhood malignancy. In neuroblastoma, AP-2β supports noradrenergic differentiation. Recently, the function of AP-2β in breast cancer (BC) has gained interest. AP-2β is associated with the lobular BC subtype. Moreover, AP-2β controls BC cell proliferation and has a prognostic impact in patients with BC. This review provides a comprehensive overview of the current knowledge about AP-2β and its function in organ development, differentiation and tumorigenesis.

The methylation level of TFAP2A is a potential diagnostic biomarker for retinoblastoma: an analytical validation study

Tumor-derived circulating tumor DNA (ctDNA) has demonstrated its excellent potential for cancer diagnosis by DNA methylome; therefore, this study aimed to identify the retinoblastoma (RB) specific methylated CpG loci as the RB diagnostic biomarkers and design a methylation specific assay to detect these biomarker from aqueous humor of RB patients. Through a genome-wide methylation profiling of tissue samples from patients with RB, normal retina and other retinal diseases, we shortlisted two CpG loci were only methylated in RB but not in normal retina or other retinal diseases. Both of these two CpG loci were located in the genome of TFAP2A. Through the screening, a primer and probe set for the two CpG loci were tested in fully methylated standards and RB tissues with a significant differentiation of RB. Our results of this assay tested in aqueous humor from RB revealed an accuracy of 92.7% for RB diagnosis. These results suggested our assay targeting the TFAP2A ctDNA methylation can be utilized for RB diagnosis and cancer monitoring.

Functional genomics of AP-2α and AP-2γ in cancers: in silico study

BACKGROUND

Among all causes of death, cancer is the most prevalent and is only outpaced by cardiovascular diseases. Molecular theory of carcinogenesis states that apoptosis and proliferation are regulated by groups of tumor suppressors or oncogenes. Transcription factors are example of proteins comprising representatives of both cancer-related groups. Exemplary family of transcription factors which exhibits dualism of function is Activating enhancer-binding Protein 2 (AP-2). Scientific reports concerning their function in carcinogenesis depend on particular family member and/or tumor type which proves the issue to be unsolved. Therefore, the present study examines role of the best-described AP-2 representatives, AP-2α and AP-2γ, through ontological analysis of their target genes and investigation what processes are differentially regulated in 21 cancers using samples deposited in Genomic Data Analysis Center (GDAC) Firehose.

METHODS

Expression data with clinical annotation was collected from TCGA-dedicated repository GDAC Firehose. Transcription factor targets were obtained from Gene Transcription Regulation Database (GTRD), TRANScription FACtor database (TRANSFAC) and Transcriptional Regulatory Relationships Unraveled by Sentence-based Text mining (TRRUST). Monocle3 R package was used for global samples profiling while Protein ANalysis THrough Evolutionary Relationships (PANTHER) tool was used to perform gene ontology analysis.

RESULTS

With RNA-seq data and Monocle3 or PANTHER tools we outlined differences in many processes and signaling pathways, separating tumor from normal tissues or tumors from each other. Unexpectedly, a number of alterations in basal-like breast cancer were identified that distinguished it from other subtypes, which could bring future clinical benefits.

CONCLUSIONS

Our findings indicate that while the AP-2α/γ role remains ambiguous, their activity is based on processes that underlie the cancer hallmarks and their expression could have potential in diagnosis of selected tumors.

Regulation of Polyomavirus Transcription by Viral and Cellular Factors

Polyomavirus infection is widespread in the human population. This family of viruses normally maintains latent infection within the host cell but can cause a range of human pathologies, especially in immunocompromised individuals. Among several known pathogenic human polyomaviruses, JC polyomavirus (JCPyV) has the potential to cause the demyelinating disease progressive multifocal leukoencephalopathy (PML); BK polyomavirus (BKPyV) can cause nephropathy in kidney transplant recipients, and Merkel cell polyomavirus (MCPyV) is associated with a highly aggressive form of skin cancer, Merkel cell carcinoma (MCC). While the mechanisms by which these viruses give rise to the relevant diseases are not well understood, it is clear that the control of gene expression in each polyomavirus plays an important role in determining the infectious tropism of the virus as well as their potential to promote disease progression. In this review, we discuss the mechanisms governing the transcriptional regulation of these pathogenic human polyomaviruses in addition to the best-studied simian vacuolating virus 40 (SV40). We highlight the roles of viral cis-acting DNA elements, encoded proteins and miRNAs that control the viral gene expression. We will also underline the cellular transcription factors and epigenetic modifications that regulate the gene expression of these viruses.

DHX33 Interacts with AP-2β To Regulate Bcl-2 Gene Expression and Promote Cancer Cell Survival

The RNA helicase DHX33 has been found to be overexpressed in human cancers, where it promotes cancer development. Previous reports have shown that DHX33 deficiency caused cancer cell apoptosis, but the underlying mechanism remains unknown. In this study, we discovered that DHX33 regulates Bcl-2 family protein expression. In multiple human cancer cell lines, DHX33 was found to stimulate the transcription of Bcl-2 Mechanistically, we found that DHX33 interacts with the AP-2β transcription factor and acts as a coactivator to stimulate Bcl-2 gene transcription. DHX33 deficiency abolished the loading of AP-2β onto the promoter of Bcl-2 and thereby reduced the recruitment of active RNA polymerase II during transcription initiation. Acute knockdown of DHX33 in multiple human cancer cells caused decreased Bcl-2 protein level, which ultimately triggered mitochondrion-mediated cellular apoptosis. In addition, we found that normal human lung and mammary epithelial cells were less sensitive to acute DHX33 knockdown, implying that cancer cells are uniquely responsive to DHX33 reduction. These data support the notion that disruption of DHX33 function could be an important application for cancer therapy.

Effect of the Large and Small T-Antigens of Human Polyomaviruses on Signaling Pathways

Viruses are intracellular parasites that require a permissive host cell to express the viral genome and to produce new progeny virus particles. However, not all viral infections are productive and some viruses can induce carcinogenesis. Irrespective of the type of infection (productive or neoplastic), viruses hijack the host cell machinery to permit optimal viral replication or to transform the infected cell into a tumor cell. One mechanism viruses employ to reprogram the host cell is through interference with signaling pathways. Polyomaviruses are naked, double-stranded DNA viruses whose genome encodes the regulatory proteins large T-antigen and small t-antigen, and structural proteins that form the capsid. The large T-antigens and small t-antigens can interfere with several host signaling pathways. In this case, we review the interplay between the large T-antigens and small t-antigens with host signaling pathways and the biological consequences of these interactions.

The biological characteristics of transcription factors AP-2α and AP-2γ and their importance in various types of cancers

The Activator Protein 2 (AP-2) transcription factor (TF) family is vital for the regulation of gene expression during early development as well as carcinogenesis process. The review focusses on the AP-2α and AP-2γ proteins and their dualistic regulation of gene expression in the process of carcinogenesis. Both AP-2α and AP-2γ influence a wide range of physiological or pathological processes by regulating different pathways and interacting with diverse molecules, i.e. other proteins, long non-coding RNAs (lncRNA) or miRNAs. This review summarizes the newest information about the biology of two, AP-2α and AP-2γ, TFs in the carcinogenesis process. We emphasize that these two proteins could have either oncogenic or suppressive characteristics depending on the type of cancer tissue or their interaction with specific molecules. They have also been found to contribute to resistance and sensitivity to chemotherapy in oncological patients. A better understanding of molecular network of AP-2 factors and other molecules may clarify the atypical molecular mechanisms occurring during carcinogenesis, and may assist in the recognition of new diagnostic biomarkers.

An Osteoporosis Risk SNP at 1p36.12 Acts as an Allele-Specific Enhancer to Modulate LINC00339 Expression via Long-Range Loop Formation

Genome-wide association studies (GWASs) have reproducibly associated variants within intergenic regions of 1p36.12 locus with osteoporosis, but the functional roles underlying these noncoding variants are unknown. Through an integrative functional genomic and epigenomic analyses, we prioritized rs6426749 as a potential causal SNP for osteoporosis at 1p36.12. Dual-luciferase assay and CRISPR/Cas9 experiments demonstrate that rs6426749 acts as a distal allele-specific enhancer regulating expression of a lncRNA (LINC00339) (∼360 kb) via long-range chromatin loop formation and that this loop is mediated by CTCF occupied near rs6426749 and LINC00339 promoter region. Specifically, rs6426749-G allele can bind transcription factor TFAP2A, which efficiently elevates the enhancer activity and increases LINC00339 expression. Downregulation of LINC00339 significantly increases the expression of CDC42 in osteoblast cells, which is a pivotal regulator involved in bone metabolism. Our study provides mechanistic insight into how a noncoding SNP affects osteoporosis by long-range interaction, a finding that could indicate promising therapeutic targets for osteoporosis.

Genetic Dissection of a Supergene Implicates Tfap2a in Craniofacial Evolution of Threespine Sticklebacks

In nature, multiple adaptive phenotypes often coevolve and can be controlled by tightly linked genetic loci known as supergenes. Dissecting the genetic basis of these linked phenotypes is a major challenge in evolutionary genetics. Multiple freshwater populations of threespine stickleback fish (Gasterosteus aculeatus) have convergently evolved two constructive craniofacial traits, longer branchial bones and increased pharyngeal tooth number, likely as adaptations to dietary differences between marine and freshwater environments. Prior QTL mapping showed that both traits are partially controlled by overlapping genomic regions on chromosome 21 and that a regulatory change in Bmp6 likely underlies the tooth number QTL. Here, we mapped the branchial bone length QTL to a 155 kb, eight-gene interval tightly linked to, but excluding the coding regions of Bmp6 and containing the candidate gene Tfap2a Further recombinant mapping revealed this bone length QTL is separable into at least two loci. During embryonic and larval development, Tfap2a was expressed in the branchial bone primordia, where allele specific expression assays revealed the freshwater allele of Tfap2a was expressed at lower levels relative to the marine allele in hybrid fish. Induced loss-of-function mutations in Tfap2a revealed an essential role in stickleback craniofacial development and show that bone length is sensitive to Tfap2a dosage in heterozygotes. Combined, these results suggest that closely linked but genetically separable changes in Bmp6 and Tfap2a contribute to a supergene underlying evolved skeletal gain in multiple freshwater stickleback populations.

miR-25-3p, Positively Regulated by Transcription Factor AP-2α, Regulates the Metabolism of C2C12 Cells by Targeting Akt1

miR-25, a member of the miR-106b-25 cluster, has been reported as playing an important role in many biological processes by numerous studies, while the role of miR-25 in metabolism and its transcriptional regulation mechanism remain unclear. In this study, gain-of-function and loss-of-function assays demonstrated that miR-25-3p positively regulated the metabolism of C2C12 cells by attenuating phosphoinositide 3-kinase (PI3K) gene expression and triglyceride (TG) content, and enhancing the content of adenosine triphosphate (ATP) and reactive oxygen species (ROS). Furthermore, the results from bioinformatics analysis, dual luciferase assay, site-directed mutagenesis, qRT-PCR, and Western blotting demonstrated that miR-25-3p directly targeted the AKT serine/threonine kinase 1 (Akt1) 3′ untranslated region (3′UTR). The core promoter of miR-25-3p was identified, and the transcription factor activator protein-2α (AP-2α) significantly increased the expression of mature miR-25-3p by binding to its core promoter in vivo, as indicated by the chromatin immunoprecipitation (ChIP) assay, and AP-2α binding also downregulated the expression of Akt1. Taken together, our findings suggest that miR-25-3p, positively regulated by the transcription factor AP-2α, enhances C2C12 cell metabolism by targeting the Akt1 gene.

Transcription factor AP-2β suppresses cervical cancer cell proliferation by promoting the degradation of its interaction partner β-catenin

Transcription factor AP-2β mediates the transcription of a number of genes implicated in mammalian development, cell proliferation, and carcinogenesis. Although the expression pattern of AP-2β has been analyzed in cervical cancer cell lines, the functions and molecular mechanism of AP-2β are unknown. Here, we found that AP-2β significantly inhibits TCF/LEF reporter activity. Moreover, AP-2β and β-catenin interact both in vitro through GST pull-down assays and in vivo by co-immunoprecipitation. We further identified the interaction regions to the DNA-binding domain of AP-2β and the 1-9 Armadillo repeats of β-catenin. Moreover, AP-2β binds with β-TrCP and promotes the degradation of endogenous β-catenin via the proteasomal degradation pathway. Immunohistochemistry analysis revealed a negative correlation between the two proteins in cervical cancer tissues and cell lines. Finally, functional analysis showed that AP-2β suppresses cervical cancer cell growth in vitro and in vivo by inhibiting the expression of Wnt downstream genes. Taken together, these findings demonstrated that AP-2β functions as a novel inhibitor of the Wnt/β-catenin signaling pathway in cervical cancer.

BMP6 Regulates Proliferation and Apoptosis of Human Sertoli Cells Via Smad2/3 and Cyclin D1 Pathway and DACH1 and TFAP2A Activation

Sertoli cells are essential for regulating normal spermatogenesis. However, the mechanisms underlying human Sertoli cell development remain largely elusive. Here we examined the function and signaling pathways of BMP6 in regulating human Sertoli cells. RT-PCR, immunocytochemistry and Western blots revealed that BMP6 and its multiple receptors were expressed in human Sertoli cells. CCK-8 and EDU assays showed that BMP6 promoted the proliferation of Sertoli cells. Conversely, BMP6 siRNAs inhibited the division of these cells. Annexin V/PI assay indicated that BMP6 reduced the apoptosis in human Sertoli cells, whereas BMP6 knockdown assumed reverse effects. BMP6 enhanced the expression levels of ZO1, SCF, GDNF and AR in human Sertoli cells, and ELISA assay showed an increase of SCF by BMP6 and a reduction by BMP6 siRNAs. Notably, Smad2/3 phosphorylation and cyclin D1 were enhanced by BMP6 and decreased by BMP6 siRNAs in human Sertoli cells. The levels of DACH1 and TFAP2A were increased by BMP6 and reduced by BMP6 siRNAs, and the growth of human Sertoli cells was inhibited by these siRNAs. Collectively, these results suggest that BMP6 regulates the proliferation and apoptosis of human Sertoli cells via activating the Smad2/3/cyclin D1 and DACH1 and TFAP2A pathway.

Characterization of the non-coding control region of polyomavirus KI isolated from nasopharyngeal samples from patients with respiratory symptoms or infection and from blood from healthy blood donors in Norway

Seroepidemiological studies showed that the human polyomavirus KI (KIPyV) is common in the human population, with age-specific seroprevalence ranging from 40-90 %. Genome epidemiological analyses demonstrated that KIPyV DNA is predominantly found in respiratory tract samples of immunocompromised individuals and children suffering from respiratory diseases, but viral sequences have also been detected in brain, tonsil, lymphoid tissue studies, plasma, blood and faeces. Little is known about the sequence variation in the non-coding control region of KIPyV variants residing in different sites of the human body and whether specific strains dominate in certain parts of the world. In this study, we sequenced the non-coding control region (NCCR) of naturally occurring KIPyV variants in nasopharyngeal samples from patients with respiratory symptoms or infection and in blood from healthy donors in Norway. In total 86 sequences were obtained, 44 of which were identical to the original isolated Stockholm 60 variant. The remaining NCCRs contained one or several mutations, none of them previously reported. The same mutations were detected in NCCRs amplified from blood and nasopharyngeal samples. Some patients had different variants in their specimens. Transient transfection studies in HEK293 cells with a luciferase reporter plasmid demonstrated that some single mutations had a significant effect on the relative early and late promoter strength compared with the Stockholm 60 promoter. The effect of the NCCR mutations on viral replication and possible virulence properties remains to be established.

Transcription Factor AP2ε: A Potential Predictor of Chemoresistance in Patients With Gastric Cancer

Chemotherapy is a mainstay of therapy for advanced gastric cancer (GC); however, owing to drug resistances, the effectiveness of chemotherapy is not satisfactory for some patients with GC. Therefore, identification of a marker that predicts treatment response is beneficial to patients. Hypermethylation of transcription factor activating enhancer-binding protein 2∊ (TFAP2E) has been implicated in chemotherapy resistance to fluorouracil-based chemotherapy in patients with colorectal cancer, but its role in GC is still unknown. In this study, we investigated TFAP2E as a predictor of treatment response in GC. We used methylation-sensitive high-resolution melting analysis to study the methylation of TFAP2E in 141 GC tissue specimens and 45 adjacent nontumor tissue specimens. In vitro experiments, we analyzed the expression and methylation of TFAP2E and to examine the sensitivity of GC cell lines to 5-fluorouracil (5-FU). The TFAP2E methylation occurred at a significantly higher incidence rate in tumor tissues compared to adjacent nontumor tissues (chi-square [χ2] = 38.919, P < .001). Hypermethylation of TFAP2E occurred more frequently in tumors with lower differentiation grades (P < .001) and was significantly associated with nonresponse to fluorouracil-based chemotherapy (P = .010). Hypermethylation was also associated with decreased expression of TFAP2E (P < .01) and nonresponse to 5-FU exposure in vitro (P < .001). Hypermethylation of TFAP2E was associated with lack of response to fluorouracil-based chemotherapy, indicating that it might be a potential predictor of treatment response in patients with GC.

The EHV-1 UL4 protein that tempers viral gene expression interacts with cellular transcription factors

The UL4 gene is conserved within the genome of defective interfering particles of equine herpesvirus type 1 (EHV-1) that mediate persistent infection. Here, we show that the UL4 protein inhibits EHV-1 reporter gene expression by decreasing the level of transcribed mRNA. The UL4 protein did not bind any gene class of EHV-1 promoters in electromobility or chromatin immunoprecipitation assays, but directly interacted with the TATA box-binding protein (TBP) and the carboxy-terminal domain of RNA polymerase II both in vitro (GST-pulldown assays) and in infected cells (coimmunoprecipitation analyses). Microarray analyses of the expression of the 78 EHV-1 genes revealed that viral late genes important for virion assembly displayed enhanced expression in cells infected with UL4-null virus as compared to wild-type or UL4-restored EHV-1. Quantitative PCR analyses showed that viral DNA replication was not retarded in cells infected with the UL4-null virus as compared to wild-type EHV-1.

Bacterial control of host gene expression through RNA polymerase II

The normal flora furnishes the host with ecological barriers that prevent pathogen attack while maintaining tissue homeostasis. Urinary tract infections (UTIs) constitute a highly relevant model of microbial adaptation in which some patients infected with Escherichia coli develop acute pyelonephritis, while other patients with bacteriuria exhibit an asymptomatic carrier state similar to bacterial commensalism. It remains unclear if the lack of destructive inflammation merely reflects low virulence or if carrier strains actively inhibit disease-associated responses in the host. Here, we identify a new mechanism of bacterial adaptation through broad suppression of RNA polymerase II–dependent (Pol II–dependent) host gene expression. Over 60% of all genes were suppressed 24 hours after human inoculation with the prototype asymptomatic bacteriuria (ABU) strain E. coli 83972, and inhibition was verified by infection of human cells. Specific repressors and activators of Pol II–dependent transcription were modified, Pol II phosphorylation was inhibited, and pathogen-specific signaling was suppressed in cell lines and inoculated patients. An increased frequency of strains inhibiting Pol II was epidemiologically verified in ABU and fecal strains compared with acute pyelonephritis, and a Pol II antagonist suppressed the disease-associated host response. These results suggest that by manipulating host gene expression, ABU strains promote tissue integrity while inhibiting pathology. Such bacterial modulation of host gene expression may be essential to sustain asymptomatic bacterial carriage by ensuring that potentially destructive immune activation will not occur.

AP-2α suppresses invasion in BeWo cells by repression of matrix metalloproteinase-2 and -9 and up-regulation of E-cadherin

Preeclampsia complicates 5-10% of pregnancies and is a leading cause of maternal/fetal morbidity and mortality. Although the cause is unknown, the reduced migration/invasion of extravillous trophoblasts is generally regarded as a key feature of preeclampsia genesis. The present study examined the expression of activator protein-2α (AP-2α), tissue inhibitor of metalloproteinase 2 (TIMP-2), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and E-cadherin in severe preeclamptic placentas and normal placentas using real-time PCR and immunohistochemistry. The expression levels of AP-2α, TIMP-2, and E-cadherin were elevated, while MMP-2 and MMP-9 levels were decreased in severe preeclamptic placentas when compared with normal placentas. To explore the underlying molecular mechanisms, BeWo cells were transfected with an AP-2α-expression construct as well as a siRNA against AP-2α. The over-expression of AP-2α decreased the invasive abilities of BeWo cells. AP-2α induction was followed by the induction of TIMP-2 and E-cadherin and a significant reduction of MMP-2 and MMP-9. Whereas in AP-2α-silencing BeWo cells, we observed the decreased expression of TIMP-2 and E-cadherin and the increased expression of MMP-2 and MMP-9. We presume that AP-2α may suppress trophoblast invasion by repression of MMP-2 and MMP-9 and up-regulation of E-cadherin, thus leading to shallow placentation in severe preeclampsia.

Regulation of the varicella-zoster virus ORF3 promoter by cellular and viral factors

The varicella zoster virus (VZV) immediate early 62 protein (IE62) activates most if not all identified promoters of VZV genes and also some minimum model promoters that contain only a TATA box element. Analysis of the DNA elements that function in IE62 activation of the VZV ORF3 promoter revealed that the 100 nucleotides before the translation start site of the ORF3 gene contains the promoter elements. This promoter lacks any functional TATA box element. Cellular transcription factors Sp1, Sp3 and YY1 bind to the promoter, and mutation of their binding sites inhibited ORF3 gene expression. VZV regulatory proteins, IE63 and ORF29, ORF61 and ORF10 proteins inhibited IE62-mediated activation of this promoter. Mutation of the Sp1/Sp3 binding site in the VZV genome did not alter VZV replication kinetics. This work suggests that Sp family proteins contribute to the activation of VZV promoters by IE62 in the absence of functional TATA box.

Transcriptional regulation of small HSP-HSF1 and beyond

The members of the small heat shock protein (sHSP) family are molecular chaperones that play major roles in development, stress responses, and diseases, and have been envisioned as targets for therapy, particularly in cancer. The molecular mechanisms that regulate their transcription, in normal, stress, or pathological conditions, are characterized by extreme complexity and subtlety. Although historically linked to the heat shock transcription factors (HSFs), the stress-induced or developmental expression of the diverse members, including HSPB1/Hsp27/Hsp25, αA-crystallin/HSPB4, and αB-crystallin/HSPB5, relies on the combinatory effects of many transcription factors. Coupled with remarkably different cis-element architectures in the sHsp regulatory regions, they confer to each member its developmental expression or stress-inducibility. For example, multiple regulatory pathways coordinate the spatio-temporal expression of mouse αA-, αB-crystallin, and Hsp25 genes during lens development, through the action of master genes, like the large Maf family proteins and Pax6, but also HSF4. The inducibility of Hsp27 and αB-crystallin transcription by various stresses is exerted by HSF-dependent mechanisms, by which concomitant induction of Hsp27 and αB-crystallin expression is observed. In contrast, HSF-independent pathways can lead to αB-crystallin expression, but not to Hsp27 induction. Not surprisingly, deregulation of the expression of sHSP is associated with various pathologies, including cancer, neurodegenerative, or cardiac diseases. However, many questions remain to be addressed, and further elucidation of the developmental mechanisms of sHsp gene transcription might help to unravel the tissue- and stage-specific functions of this fascinating class of proteins, which might prove to be crucial for future therapeutic strategies. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.

Role of COX-2 in lymphangiogenesis and restoration of lymphatic flow in secondary lymphedema

The pathophysiology of secondary lymphedema remains poorly understood. To clarify the roles of cyclooxygenase (COX)-2 in enhancement of lymphangiogenesis during secondary lymphedema, we tested a mouse tail model and evaluated the recurrence of lymph flow. To induce lymphedema, a circumferential incision was made in the tail of anesthetized mice to sever the dermal lymphatic vessels. The maximum diameters of the tails were measured weekly. We found that the diameters of the tails around the wounds were markedly increased after surgery, and reached maximum size 2 weeks after wounding in mice without a COX-2 inhibitor, celecoxib (Celecoxib-). Expression of COX-2 in wound granulation tissues was markedly increased 1 week after surgery compared with unwounded naive control mice. In Celecoxib-, recurrence of lymphatic flow in the wound granulation tissues was detected 3 weeks after surgical treatment. In contrast, lymphatic flow was markedly suppressed in mice treated with celecoxib (Celecoxib+). Newly formed lymphatic structures were identified in the granulation tissues formed at wounded lesions in Celecoxib-, whereas those were markedly suppressed in Celecoxib+. Interstitial tissue pressures in the distal areas of the tail wounds were markedly increased in Celecoxib+ with reduced expression of vascular endothelial cell growth factor (VEGF)-C. F4/80-positive cells were accumulated to the wound granulation tissues in Celecoxib-, and the accumulation of these cells was suppressed in Celecoxib+. Prostaglandin E(2) (PGE(2)) upregulated the expressions of VEGF-A and VEGF-C in cultured macrophages, but not human lymphatic microvascular endothelial cells. The present study therefore suggests that lymphangiogenesis, together with recurrence of lymph flow after surgical induction of lymphedema, is upregulated by COX-2 possibly via generation of PGs.

Protein-binding microarray analysis of tumor suppressor AP2α target gene specificity

Cheap and massively parallel methods to assess the DNA-binding specificity of transcription factors are actively sought, given their prominent regulatory role in cellular processes and diseases. Here we evaluated the use of protein-binding microarrays (PBM) to probe the association of the tumor suppressor AP2α with 6000 human genomic DNA regulatory sequences. We show that the PBM provides accurate relative binding affinities when compared to quantitative surface plasmon resonance assays. A PBM-based study of human healthy and breast tumor tissue extracts allowed the identification of previously unknown AP2α target genes and it revealed genes whose direct or indirect interactions with AP2α are affected in the diseased tissues. AP2α binding and regulation was confirmed experimentally in human carcinoma cells for novel target genes involved in tumor progression and resistance to chemotherapeutics, providing a molecular interpretation of AP2α role in cancer chemoresistance. Overall, we conclude that this approach provides quantitative and accurate assays of the specificity and activity of tumor suppressor and oncogenic proteins in clinical samples, interfacing genomic and proteomic assays.

Roles of prostaglandin E2-EP3/EP4 receptor signaling in the enhancement of lymphangiogenesis during fibroblast growth factor-2-induced granulation formation

OBJECTIVE

One of the hallmarks of inflammation is lymphangiogesis that drains the interstitial fluids. During chronic inflammation, angiogenesis is induced by a variety of inflammatory mediators, such as prostaglandins (PGs). However, it remains unknown whether they enhance lymphangiogenesis. We examined the roles of cyclooxygenase-2 (COX-2) and PGE2 receptor signaling in enhancement of lymphangiogenesis during proliferative inflammation.

METHODS AND RESULTS

Lymphangiogenesis estimated by podoplanin/vascular endothelial growth factor (VEGF) receptor-3/LYVE-1 expression was upregulated during proliferative inflammation seen around and into subcutaneous Matrigel plugs containing fibroblast growth factor-2 (125 ng/site). A COX-2 inhibitor (celecoxib) significantly reduced lymphangiogenesis in a dose-dependent manner, whereas topical PGE2 enhanced lymphangiogenesis. Topical injection of fluorescein isothiocyanate-dextran into the Matrigel revealed that lymphatic flow from the Matrigels was COX-2 dependent. Lymphangiogenesis was suppressed in the granulation tissues of mice lacking either EP3 or EP4, suggesting that these molecules are receptors in response to endogenous PGE2. An EP3-selective agonist (ONO-AE-248) increased the expression of VEGF-C and VEGF-D in cultured macrophages, whereas an EP4-selective agonist (ONO-AE1-329) increased VEGF-C expression in cultured macrophages and increased VEGF-D expression in cultured fibroblasts.

CONCLUSIONS

Our findings suggest that COX-2 and EP3/EP4 signaling contributes to lymphangiogenesis in proliferative inflammation, possibly via induction of VEGF-C and VEGF-D, and may become a therapeutic target for controlling lymphangiogenesis.

A catalogue of eukaryotic transcription factor types, their evolutionary origin, and species distribution

Transcription factors (TFs) play key roles in the regulation of gene expression by binding in a sequence-specific manner to genomic DNA. In eukaryotes, DNA binding is achieved by a wide range of structural forms and motifs. TFs are typically classified by their DNA-binding domain (DBD) type. In this chapter, we catalogue and survey 91 different TF DBD types in metazoa, plants, fungi, and protists. We briefly discuss well-characterized TF families representing the major DBD superclasses. We also examine the species distributions and inferred evolutionary histories of the various families, and the potential roles played by TF family expansion and dimerization.

Transcription factor AP-2β regulates the neurotransmitter phenotype and maturation of chromaffin cells

During development, sympathetic neurons and chromaffin cells originate from bipotential sympathoadrenal (SA) progenitors arising from neural crests (NC) in the trunk regions. Recently, we showed that AP-2β, a member of the AP2 family, plays a critical role in the development of sympathetic neurons and locus coeruleus and their norepinephrine (NE) neurotransmitter phenotype. In the present study, we investigated the potential role of AP-2β in the development of NC-derived neuroendocrine chromaffin cells of the adrenal medulla and the epinephrine (EPI) phenotype determination. In support of its role in chromaffin cell development, AP-2β is prominently expressed in both embryonic and adult adrenal medulla. In adrenal chromaffin cells of the AP-2β(-/-) mouse, the expression levels of catecholamine biosynthesizing enzymes, dopamine β-hydroxylase (DBH) and phenylethanolamine-N-methyl-transferase (PNMT), as well as the SA-specific transcription factor, Phox2b, are significantly reduced compared to wild type. In addition, ultrastructural analysis demonstrated that the formation of large secretory vesicles, a hallmark of differentiated chromaffin cells, is defective in AP-2β(-/-) mice. Furthermore, the level of EPI content is largely diminished (>80%) in the adrenal gland of AP-2β(-/-) mice. Chromatin immunoprecipitation (ChIP) assays of rat adrenal gland showed that AP-2β binds to the upstream promoter of the PNMT gene in vivo; strongly suggesting that it is a direct target gene. Overall, our data suggest that AP-2β plays critical roles in the epinephrine phenotype and maturation of adrenal chromaffin cells.

Transcription of human resistin gene involves an interaction of Sp1 with peroxisome proliferator-activating receptor gamma (PPARgamma)

BACKGROUND

Resistin is a cysteine rich protein, mainly expressed and secreted by circulating human mononuclear cells. While several factors responsible for transcription of mouse resistin gene have been identified, not much is known about the factors responsible for the differential expression of human resistin.

METHODOLOGY/PRINCIPAL FINDING

We show that the minimal promoter of human resistin lies within approximately 80 bp sequence upstream of the transcriptional start site (-240) whereas binding sites for cRel, CCAAT enhancer binding protein alpha (C/EBP-alpha), activating transcription factor 2 (ATF-2) and activator protein 1 (AP-1) transcription factors, important for induced expression, are present within sequences up to -619. Specificity Protein 1(Sp1) binding site (-276 to -295) is also present and an interaction of Sp1 with peroxisome proliferator activating receptor gamma (PPARgamma) is necessary for constitutive expression in U937 cells. Indeed co-immunoprecipitation assay demonstrated a direct physical interaction of Sp1 with PPARgamma in whole cell extracts of U937 cells. Phorbol myristate acetate (PMA) upregulated the expression of resistin mRNA in U937 cells by increasing the recruitment of Sp1, ATF-2 and PPARgamma on the resistin gene promoter. Furthermore, PMA stimulation of U937 cells resulted in the disruption of Sp1 and PPARgamma interaction. Chromatin immunoprecipitation (ChIP) assay confirmed the recruitment of transcription factors phospho ATF-2, Sp1, Sp3, PPARgamma, chromatin modifier histone deacetylase 1 (HDAC1) and the acetylated form of histone H3 but not cRel, C/EBP-alpha and phospho c-Jun during resistin gene transcription.

CONCLUSION

Our findings suggest a complex interplay of Sp1 and PPARgamma along with other transcription factors that drives the expression of resistin in human monocytic U937 cells.

Roles of AP-2 transcription factors in the regulation of cartilage and skeletal development

During embryogenesis, most of the mammalian skeletal system is preformed as cartilaginous structures that ossify later. The different stages of cartilage and skeletal development are well described, and several molecular factors are known to influence the events of this enchondral ossification, especially transcription factors. Members of the AP-2 family of transcription factors play important roles in several cellular processes, such as apoptosis, migration and differentiation. Studies with knockout mice demonstrate that a main function of AP-2s is the suppression of terminal differentiation during embryonic development. Additionally, the specific role of these molecules as regulators during chondrogenesis has been characterized. This review gives an overview of AP-2s, and discusses the recent findings on the AP-2 family, in particular AP-2alpha, AP-2beta, and AP-2epsilon, as regulators of cartilage and skeletal development.

Regulation of gene expression in primate polyomaviruses

Polyomaviruses are a growing family of small DNA viruses with a narrow tropism for both the host species and the cell type in which they productively replicate. Species host range may be constrained by requirements for precise molecular interactions between the viral T antigen, host replication proteins, including DNA polymerase, and the viral origin of replication, which are required for viral DNA replication. Cell type specificity involves, at least in part, transcription factors that are necessary for viral gene expression and restricted in their tissue distribution. In the case of the human polyomaviruses, BK virus (BKV) replication occurs in the tubular epithelial cells of the kidney, causing nephropathy in kidney allograft recipients, while JC virus (JCV) replication occurs in the glial cells of the central nervous system, where it causes progressive multifocal leukoencephalopathy. Three new human polyomaviruses have recently been discovered: MCV was found in Merkel cell carcinoma samples, while Karolinska Institute Virus and Washington University Virus were isolated from the respiratory tract. We discuss control mechanisms for gene expression in primate polyomaviruses, including simian vacuolating virus 40, BKV, and JCV. These mechanisms include not only modulation of promoter activities by transcription factor binding but also enhancer rearrangements, restriction of DNA methylation, alternate early mRNA splicing, cis-acting elements in the late mRNA leader sequence, and the production of viral microRNA.

Progress in studies on the DEK protein and its involvement in cellular apoptosis

DEK protein is an ubiquitous phosphorylated nuclear protein. Specific binding of DEK to DNA could change the topology of DNA and then affect the gene activity of the underlying DNA sequences. It is speculated that there might be some potential relationship between the stress reaction of cells and DEK proteins. The phosphorylation status of DEK protein is altered during death-receptor-mediated cell apoptosis. Both phosphorylation and poly(ADP-ribosyl)ation could promote the release of DEK from apoptotic nuclei to extracellular environment, and in this case DEK becomes a potential autoantigen of some autoimmune diseases. The available evidence powerfully suggests that DEK protein is closely relevant to apoptosis. The overexpression of DEK protein has dual function in cell apoptosis, in terms of inhibiting or triggering cell apoptosis.

Evidence for modulation of BAG3 by polyomavirus JC early protein

Polyomavirus JC (JCV) infects oligodendrocytes and astrocytes in the brain and is the cause of the demyelinating disease progressive multifocal leukoencephalopathy (PML). In cell culture, JCV infection is characterized by severe damage to cellular DNA, which begins early in infection, and a viral cytopathic effect, which is observed late in infection. Nevertheless, these JCV-infected cells show a low level of apoptosis, at both the early and late stages of infection. This suggests that there is conflicting interplay between viral anti-apoptotic pathways that seek to optimize virus production, e.g. through T antigen (T-Ag)-p53 interaction, and cellular pro-apoptotic pathways that seek to eliminate virally infected cells. The apoptosis regulatory protein BAG3 is a member of the human Bcl-2-associated athanogene (BAG) family of proteins, which function as molecular co-chaperones through their interaction with Hsc70/Hsp70 and function in the regulation of the cellular stress response, proliferation and apoptosis. This study showed that BAG3 protein is downregulated upon JCV infection and that this effect is mediated by JCV T-Ag via repression of the BAG3 promoter. The site of action of T-Ag was mapped to an AP2 site in the BAG3 promoter, and gel shift and chromatin immunoprecipitation assays showed that T-Ag inhibited AP2 binding to this site, resulting in downregulation of BAG3 promoter expression. Using BAG3 and T-Ag expression and BAG3 siRNA, it was found that BAG3 and T-Ag had antagonistic effects on the induction of apoptosis, being anti-apoptotic and pro-apoptotic, respectively. The significance of these interactions to the JCV life cycle is discussed.

Cell-type specific regulation of gene expression by simian virus 40 T antigens

SV40 transforms cells through the action of two oncoproteins, large T antigen and small t antigen. Small t antigen targets phosphatase PP2A, while large T antigen stimulates cell proliferation and survival by action on multiple proteins, including the tumor suppressors Rb and p53. Large T antigen also binds components of the transcription initiation complex and several transcription factors. We examined global gene expression in SV40-transformed mouse embryo fibroblasts, and in enterocytes obtained from transgenic mice. SV40 transformation alters the expression of approximately 800 cellular genes in both systems. Much of this regulation is observed in both MEFs and enterocytes and is consistent with T antigen action on the Rb-E2F pathway. However, the regulation of many genes is cell-type specific, suggesting that unique signaling pathways are activated in different cell types upon transformation, and that the consequences of SV40 transformation depends on the type of cell targeted.

Retinoic acid (RA) regulates 17beta-hydroxysteroid dehydrogenase type 2 expression in endometrium: interaction of RA receptors with specificity protein (SP) 1/SP3 for estradiol metabolism

CONTEXT

The enzyme 17beta-hydroxysteroid dehydrogenase type 2 (HSD17B2) exerts a local antiestrogenic effect by metabolizing biologically active estradiol to inactive estrone in endometrial epithelial cells. Retinoic acid (RA) induces HSD17B2 expression, but the underlying mechanism is not known.

OBJECTIVE

Our objective was to elucidate the molecular mechanisms responsible for HSD17B2 expression in human endometrial cells.

METHOD

Human endometrial Ishikawa and RL95-2 cell lines were cultured in the presence or absence of RA to analyze endogenous HSD17B2 expression, transcription factor complex formation, and promoter activity.

RESULTS

RA induced HSD17B2 mRNA levels in a dose- and time-dependent manner in endometrial cells. The RA antagonist ANG11273 abolished RA-induced HSD17B2 expression. Small interfering RNA ablation of RA receptor (RAR)alpha or retinoid X receptor (RXR)alpha completely blocked RA-induced HSD17B2 gene expression. Analysis of serial deletion and site-directed mutants of the HSD17B2 promoter fused to a reporter gene indicated that RA induction requires a cis-regulatory sequence that binds the specificity protein (SP) class of transcription factors. Chromatin-immunoprecipitation-PCR and gel-shift assays showed that RARalpha/RXRalpha and SP1/SP3 interact with this HSD17B2 promoter sequence. Small interfering RNA ablation of SP1 and SP3 expression markedly decreased HSD17B2 basal expression and blocked RA-induced expression. Finally, immunoprecipitationimmunoblotting demonstrated RA-induced interactions between RARalpha/RXRalpha and SP1/SP3 in intact endometrial cells.

CONCLUSIONS

In endometrial epithelial cells, RA stimulates formation of a multimeric complex comprised of RARalpha/RXRalpha tethered to transcription factors SP1 and SP3 on the HSD17B2 promoter. Assembly of this transcriptional complex is necessary for RA induction of HSD17B2 expression and may be an important mechanism for local estradiol inactivation in the endometrium.

Bovine kappa-casein gene promoter haplotypes with potential implications for milk protein expression

Genetic analysis of the kappa-casein gene (CSN3) promoter regions of 42 cattle representing 9 different breeds revealed that 2 distinct haplotypes (A and B) exist at this locus, differing from each other by single base changes at positions -514 (T/G), -426 (T/C), and -384 (T/C), where haplotype A has bases T, T, and T and haplotype B has bases G, C, and C. The AA and AB haplotypes were found to occur at a higher frequency in the animals tested, with 69.0 and 21.4% being homozygous and heterozygous, respectively. The sequences that include these polymorphisms are potentially important in transcriptional regulation of the kappa-casein gene, because they contain putative sites for binding of many transcription factors. Linkage disequilibrium between the kappa-casein promoter haplotype and either one of the 2 major kappa-casein coding sequence haplotypes was not evident. The A allele is dominant in all groups (dairy, beef, and dual purpose) with an allele frequency of 80% and is higher among high-yielding dairy animals (88.9%) than among beef animals (75%). The AB haplo-type is comparatively rare in the dairy cattle (11.1%) compared with both beef and dual-purpose animals. The BB haplotype, though rare overall (9.5%), is much higher in dual-purpose animals (18.8%) than dairy (5.6%) animals. In contrast, the B allele is much more representative of the kappa-casein promoters from other ruminants.

Activator protein-2 in carcinogenesis with a special reference to breast cancer-A mini review

Activator protein-2 (AP-2) transcription factors are involved in the regulation of cell proliferation, differentiation, apoptosis and carcinogenesis. AP-2alpha has been suggested to function as a tumor suppressor in many cancers and AP-2gamma to be a marker of testicular and germ cell malignancies. At least 3 of the 5 AP-2 family members identified to date, AP-2alpha, AP-2beta and AP-2gamma, are known to be expressed in breast tissue and thought to coordinate the growth and development of the breast via regulation of several breast-related genes such as human epidermal growth factor receptor-2 (HER2) and estrogen receptor (ER). The function of AP-2alpha seems to be tumor suppressive in breast tissue, whereas the role of the other AP-2 family members is less well known. In this review, we summarize the current knowledge of AP-2 in carcinogenesis, especially in breast cancer.

New technologies used in the study of human melanoma

The amount of information on tumor biology has expanded enormously, essentially due to the completion of the human genome sequencing and to the application of new technologies that represent an exciting breakthrough in molecular analysis. Often these data spring from experimental procedures, such as a serial analysis of gene expression (SAGE) and DNA microarrays, which cannot be defined as hypothesis-driven: it may appear to be a "brute force" approach through which no information can be directly generated concerning the specific functions of selected genes in a definite context. However, interesting results are fruitfully generated, and thus it is important to consider the enormous potential these new technologies possess and to learn how to apply this novel form of knowledge in the emerging field of molecular medicine. This review, after a limited outline regarding several classic aspects of human cutaneous melanoma biology, genetics, and clinical approaches, will focus on the proficient use of up-to-date technologies in the study of the neoplastic disease and on their capability to provide effective support to conventional approaches in melanoma diagnosis, prognosis, and treatment.

Transcriptional Regulation of ULBP1, a Human Ligand of the NKG2D Receptor

Tumor cells expressing ligands of the NKG2D receptor stimulate anti-tumor immunity mediated by natural killer and T cells. In humans, NKG2D ligands (NKG2DL) are encoded by MIC and ULBP proteins. NKG2DL exhibit highly restricted expression in healthy tissues but are widely expressed in tumors. However, regulation of each NKG2DL differs substantially in different cancer cells. In this study, we characterized the mechanisms that regulate the expression of ULBP1. We show that the transcription of ULBP1 strictly depends on the binding of Sp1 and Sp3 to a CRE(1) site located in the ULBP1 minimal promoter. The mutation or deletion of this Sp1/Sp3 binding site abolished the transcription of ULBP1. It also diminished the transactivation of ULBP1 promoter by Sp3 overexpression, but not by Sp1, indicating that Sp3 is the main transcription factor that regulates ULBP1 through the CRE(1) site. Experiments in SL2 cells showed that the ULBP1 promoter was inactive in the absence of the Sp proteins and indicate that Sp3 is the essential activator of ULBP1 transcription, because the overexpression of Sp3 up-regulated its promoter activity > 500-fold. Additionally, we demonstrated that AP-2alpha repressed the expression of ULBP1 in HeLa cells by interfering with the binding of Sp3 and Sp1 to the ULBP1 promoter. These data indicate that Sp1, Sp3, and AP-2alpha may play an important role in the immunosurveillance against cancer. Finally, the definition of ULBP1 regulation may have implications for development of new therapeutic strategies against cancer cells.

Proteomic identification of AP2 gamma as a rat placental lactogen II trophoblast cell-specific enhancer binding protein

The factors that regulate the developmental expression of the rodent prolactin gene family in placenta remain poorly defined. We previously identified an enhancer element in the 5' flanking region of one family member, rat placental lactogen II (rPLII), which could target reporter gene expression to the placenta in transgenic mice; this enhancer functioned in the Rcho rat trophoblast cell line but not in the rat pituitary GC cell line. In further experiments to identify the factors that bind this element, we have selectively enriched for DNA binding proteins in nuclear extract from Rcho cells using magnetic beads coupled to a 43-bp enhancer oligonucleotide. Tryptic peptides of bound proteins were analyzed by HPLC coupled off-line to matrix-assisted laser desorption ionization time of flight mass spectrometry. Several peptides of AP2 gamma, a key trophoblast cell-specific transcription factor, were identified. Gel mobility shift assays using AP2 gamma-specific antiserum and mutant enhancer oligonucleotides demonstrated binding specifically to the FP2 DNase I-protected region of the element, identifying an atypical binding site for this factor. In cotransfection assays in rat pituitary GC cells, AP2 gamma transactivated the enhancer via this region. Chromatin immunoprecipitation assays confirmed AP2 gamma occupancy of the enhancer region in situ in the nuclei of Rcho giant cells. These data support a role for AP2 gamma in the placental giant cell-specific expression of the rPLII gene and provide the first direct evidence for the involvement of a placental-specific transcription factor in the regulation of a member of this gene family.

AP-2gamma induces p21 expression, arrests cell cycle, and inhibits the tumor growth of human carcinoma cells

Activating enhancer-binding protein 2gamma (AP-2gamma) is a member of the developmentally regulated AP-2 transcription factor family that regulates the expression of many downstream genes. Whereas the effects of AP-2alpha overexpression on cell growth are fairly well established, the cellular effects of AP-2gamma overexpression are less well studied. Our new findings show that AP-2gamma significantly upregulates p21 mRNA and proteins, inhibits cell growth, and decreases clonogenic survival. Cell cycle analysis revealed that forced AP-2gamma expression induced G1-phase arrest, decreased DNA synthesis, and decreased the fraction of cells in S phase. AP-2gamma expression also led to cyclin D1 repression, decreased Rb phosphorylation, and decreased E2F activity in breast carcinoma cells. AP-2gamma binding to the p21 promoter was observed in vivo, and the absence of growth inhibition in response to AP-2gamma expression in p21(-/-) cells demonstrated that p21 caused, at least in part, AP-2-induced cell cycle arrest. Finally, the tumor growth of human breast carcinoma cells in vivo was inhibited by the expression of AP-2gamma relative to empty vector-infected cells, suggesting that AP-2gamma acts as a tumor suppressor. In summary, expression of either AP-2gamma or AP-2alpha inhibited breast carcinoma cell growth; thus, these genes may be therapeutic targets for breast cancer.

Activator protein-2 overexpression accounts for increased insulin receptor expression in human breast cancer

Various studies have shown that the insulin receptor (IR) is increased in most human breast cancers, and both ligand-dependent malignant transformation and increased cell growth occur in cultured breast cells overexpressing the IR. However, although numerous in vivo and in vitro observations have indicated an important contributory role for the IR in breast cancer cell biology, the molecular mechanisms accounting for increased IR expression in breast tumors have not previously been elucidated. Herein, we did immunoblot analyses of nuclear protein from cultured breast cancer cells and normal and tumoral tissues from breast cancer patients combined with promoter studies by using a series of human wild-type and mutant IR promoter constructs. We provide evidence that IR overexpression in breast cancer is dependent on the assembly of a transcriptionally active multiprotein-DNA complex, which includes the high-mobility group A1 (HMGA1) protein, the developmentally regulated activator protein-2 (AP-2) transcription factor and the ubiquitously expressed transcription factor Sp1. In cultured breast cancer cells and human breast cancer specimens, the expression of AP-2 was significantly higher than that observed in cells and tissues derived from normal breast, and this overexpression paralleled the increase in IR expression. However, AP-2 DNA-binding activity was undetectable with the IR gene promoter, suggesting that transactivation of this gene by AP-2 might occur indirectly through physical and functional cooperation with HMGA1 and Sp1. Our findings support this hypothesis and suggest that in affected individuals, hyperactivation of the AP-2 gene through the overexpression of IR may play a key role in breast carcinogenesis.