LINE1 family member is negative regulator of HLA-G expression

The Ty1 retrotransposon harbors a DNA region that performs dual functions as both a gene silencing and chromatin insulator

In various eukaryotic kingdoms, long terminal repeat (LTR) retrotransposons repress transcription by infiltrating heterochromatin generated within their elements. In contrast, the budding yeast LTR retrotransposon Ty1 does not itself undergo transcriptional repression, although it is capable of repressing the transcription of the inserted genes within it. In this study, we identified a DNA region within Ty1 that exerts its silencing effect via sequence orientation. We identified a DNA region within the Ty1 group-specific antigen (GAG) gene that causes gene silencing, termed GAG silencing (GAGsi), in which the silent chromatin in the GAGsi region is created by euchromatin-specific histone modifications. A characteristic inverted repeat (IR) sequence is present at the 5' end of this region, forming a chromatin boundary between promoter-specific chromatin upstream of the IR sequence and silent chromatin downstream of the IR sequence. In addition, Esc2 and Rad57, which are involved in DNA repair, were required for GAGsi silencing. Finally, the chromatin boundary was required for the transcription of Ty1 itself. Thus, the GAGsi sequence contributes to the creation of a chromatin environment that promotes Ty1 transcription.

Harnessing the potential of HLA-G in cancer therapy: advances, challenges, and prospects

Immune checkpoint blockades have been prized in circumventing and ablating the impediments posed by immunosuppressive receptors, reaching an exciting juncture to be an innovator in anticancer therapy beyond traditional therapeutics. Thus far, approved immune checkpoint blockades have principally targeted PD-1/PD-L1 and CTLA-4 with exciting success in a plethora of tumors and yet are still trapped in dilemmas of limited response rates and adverse effects. Hence, unveiling new immunotherapeutic targets has aroused immense scientific interest in the hope of expanding the clinical application of immune checkpoint blockades to scale new heights. Human leukocyte antigen-G (HLA-G), a non-classical major histocompatibility complex (MHC) class I molecule, is enriched on various malignant cells and is involved in the hindrance of immune effector cells and the facilitation of immunosuppressive cells. HLA-G stands out as a crucial next-generation immune checkpoint showing great promise for the benefit of cancer patients. Here, we provide an overview of the current understanding of the expression pattern and immunological functions of HLA-G, as well as its interaction with well-characterized immune checkpoints. Since HLA-G can be shed from the cell surface or released by various cells as free soluble HLA-G (sHLA-G) or as part of extracellular vesicles (EVs), namely HLA-G-bearing EVs (HLA-GEV), we discuss the potential of sHLA-G and HLA-GEV as predictive biomarkers. This review also addresses the advancement of HLA-G-based therapies in preclinical and clinical settings, with a focus on their clinical application in cancer.

The Life and Science of Professor Tsuneko Okazaki, and her time at Fujita Health University

Distinguished Professor Emeritus Tsuneko Okazaki is a hero of science. Together with her late husband, Professor Reiji Okazaki, she discovered that DNA replication involves the discontinuous synthesis of the DNA lagging strand by intermediates of, what is now called, "Okazaki fragments." She has been a pioneer for women in science and, in 1983, became the first female full Professor at Nagoya University. From 1997 to 2012, she was a full Professor and later a Visiting Professor at Fujita Health University, and this review zooms in on that period. Besides a summary of her career, this article also includes personal memories of researchers who worked with Professor Okazaki.

High-resolution DNA methylation screening of the major histocompatibility complex in multiple sclerosis

Background

The HLA-DRB1 gene in the major histocompatibility complex (MHC) region in chromosome 6p21 is the strongest genetic factor identified as influencing multiple sclerosis (MS) susceptibility. DNA methylation changes associated with MS have been consistently detected at the MHC region. However, understanding the full scope of epigenetic regulations of the MHC remains incomplete, due in part to the limited coverage of this region by standard whole genome bisulfite sequencing or array-based methods.

Methods

We developed and validated an MHC capture protocol coupled with bisulfite sequencing and conducted a comprehensive analysis of the MHC methylation landscape in blood samples from 147 treatment naïve MS study participants and 129 healthy controls.

Results

We identified 132 differentially methylated region (DMRs) within MHC region associated with disease status. The DMRs overlapped with established MS risk loci. Integration of the MHC methylome with human leukocyte antigen (HLA) genetic data indicate that the methylation changes are significantly associated with HLA genotypes. Using DNA methylation quantitative trait loci (mQTL) mapping and the causal inference test (CIT), we identified 643 cis-mQTL-DMRs paired associations, including 71 DMRs possibly mediating causal relationships between 55 single nucleotide polymorphisms (SNPs) and MS risk.

Results

The results describe MS-associated methylation changes in MHC region and highlight the association between HLA genotypes and methylation changes. Results from the mQTL and CIT analyses provide evidence linking MHC region variations, methylation changes, and disease risk for MS.

Development of a humanized HLA-A30 transgenic mouse model

Background

There are remarkable genetic differences between animal major histocompatibility complex (MHC) systems and the human leukocyte antigen (HLA) system. HLA transgenic humanized mouse model systems offer a much better method to study the HLA‐A‐related principal mechanisms for vaccine development and HLA‐A‐restricted responses against infection in human.

Methods

A recombinant gene encoding the chimeric HLA‐A30 monochain was constructed. This HHD molecule contains the following: α1‐α2 domains of HLA‐A30, α3 and cytoplasmic domains of H‐2D^b, linked at its N‐terminus to the C‐terminus of human β2m by a 15‐amino‐acid peptide linker. The recombinant gene encoding the chimeric HLA‐A30 monochain cassette was introduced into bacterial artificial chromosome (BAC) CH502‐67J3 containing the HLA‐A01 gene locus by Red‐mediated homologous recombination. Modified BAC CH502‐67J3 was microinjected into the pronuclei of wild‐type mouse oocytes. This humanized mouse model was further used to assess the immune responses against influenza A virus (H1N1) pdm09 clinically isolated from human patients. Immune cell population, cytokine production, and histopathology in the lung were analyzed.

Results

We describe a novel human β2m‐HLA‐A30 (α1α2)‐H‐2D^b (α3 transmembrane cytoplasmic) (HHD) monochain transgenic mouse strain, which contains the intact HLA‐A01 gene locus including 49 kb 5′‐UTR and 74 kb 3′‐UTR of HLA‐A01*01. Five transgenic lines integrated into the large genomic region of HLA‐A gene locus were obtained, and the robust expression of exogenous transgene was detected in various tissues from A30‐18# and A30‐19# lines encompassing the intact flanking sequences. Flow cytometry revealed that the introduction of a large genomic region in HLA‐A gene locus can influence the immune cell constitution in humanized mice. Pdm09 infection caused a similar immune response among HLA‐A30 Tg humanized mice and wild‐type mice, and induced the rapid increase of cytokines, including IFN‐γ, TNF‐α, and IL‐6, in both HLA‐A30 humanized Tg mice and wild‐type mice. The expression of HLA‐A30 transgene was dramatically promoted in tissues from A30‐9# line at 3 days post‐infection (dpi).

Conclusions

We established a promising preclinical research animal model of HLA‐A30 Tg humanized mouse, which could accelerate the identification of novel HLA‐A30‐restricted epitopes and vaccine development, and support the study of HLA‐A‐restricted responses against infection in humans.

Human Artificial Chromosomes and Their Transfer to Target Cells

Human artificial chromosomes (HACs) have been developed as genetic vectors with the capacity to carry large transgenic constructs or entire gene loci. HACs represent either truncated native chromosomes or de novo synthesized genetic constructs. The important features of HACs are their ultra-high capacity and ability to self-maintain as independent genetic elements, without integrating into host chromosomes. In this review, we discuss the development and construction methods, structural and functional features, as well as the areas of application of the main HAC types. Also, we address one of the most technically challenging and time-consuming steps in this technology - the transfer of HACs from donor to recipient cells.

The Human Leukocyte Antigen G as an Immune Escape Mechanism and Novel Therapeutic Target in Urological Tumors

The non-classical human leukocyte antigen G (HLA-G) is a potent regulatory protein involved in the induction of immunological tolerance. This is based on the binding of membrane-bound as well as soluble HLA-G to inhibitory receptors expressed on various immune effector cells, in particular NK cells and T cells, leading to their attenuated functions. Despite its restricted expression on immune-privileged tissues under physiological conditions, HLA-G expression has been frequently detected in solid and hematopoietic malignancies including urological cancers, such as renal cell and urothelial bladder carcinoma and has been associated with progression of urological cancers and poor outcome of patients: HLA-G expression protects tumor cells from anti-tumor immunity upon interaction with its inhibitory receptors by modulating both the phenotype and function of immune cells leading to immune evasion. This review will discuss the expression, regulation, functional and clinical relevance of HLA-G expression in urological tumors as well as its use as a putative biomarker and/or potential therapeutic target for the treatment of renal cell carcinoma as well as urothelial bladder cancer.

Role of HLA-G in Viral Infections

The human leukocyte antigen (HLA)-G is a non-classical HLA class I molecule, which has distinct features to classical HLA-A, -B, -C antigens, such as a low polymorphism, different splice variants, highly restricted, tightly regulated expression and immune modulatory properties. HLA-G expression in tumor cells and virus-infected cells, as well as the release of soluble HLA-G leads to escape from host immune surveillance. Increased knowledge of the link between HLA-G expression, viral infection and disease progression is urgently required, which highlights the possible use of HLA-G as novel diagnostic and prognostic biomarker for viral infections, but also as therapeutic target. Therefore, this review aims to summarize the expression, regulation, function and impact of HLA-G in the context of different viral infections including virus-associated cancers. The characterization of HLA-G-driven immune escape mechanisms involved in the interactions between host cells and viruses might result in the design of novel immunotherapeutic strategies targeting HLA-G and/or its interaction with its receptors on immune effector cells.

HLA-G: An Important Mediator of Maternal-Fetal Immune-Tolerance

Maternal-fetal immune-tolerance occurs throughout the whole gestational trimester, thus a mother can accept a genetically distinct fetus without immunological aggressive behavior. HLA-G, one of the non-classical HLA class I molecules, is restricted-expression at extravillous trophoblast. It can concordantly interact with various kinds of receptors mounted on maternally immune cells residing in the uterus (e.g. CD4+ T cells, CD8+ T cells, natural killer cells, macrophages, and dendritic cells) for maintaining immune homeostasis of the maternal-fetus interface. HLA-G is widely regarded as the pivotal protective factor for successful pregnancies. In the past 20 years, researches associated with HLA-G have been continually published. Indeed, HLA-G plays a mysterious role in the mechanism of maternal-fetal immune-tolerance. It can also be ectopically expressed on tumor cells, infected sites and other pathologic microenvironments to confer a significant local tolerance. Understanding the characteristics of HLA-G in immunologic tolerance is not only beneficial for pathological pregnancy, but also helpful to the therapy of other immune-related diseases, such as organ transplant rejection, tumor migration, and autoimmune disease. In this review, we describe the biological properties of HLA-G, then summarize our understanding of the mechanisms of fetomaternal immunologic tolerance and the difference from transplant tolerance. Furthermore, we will discuss how HLA-G contributes to the tolerogenic microenvironment during pregnancy. Finally, we hope to find some new aspects of HLA-G in fundamental research or clinical application for the future.

Pluripotent stem cell-based gene therapy approach: human de novo synthesized chromosomes

A novel approach in gene therapy was introduced 20 years ago since artificial non-integrative chromosome-based vectors containing gene loci size inserts were engineered. To date, different human artificial chromosomes (HAC) were generated with the use of de novo construction or "top-down" engineering approaches. The HAC-based therapeutic approach includes ex vivo gene transferring and correction of pluripotent stem cells (PSCs) or highly proliferative modified stem cells. The current progress in the technology of induced PSCs, integrating with the HAC technology, resulted in a novel platform of stem cell-based tissue replacement therapy for the treatment of genetic disease. Nowadays, the sophisticated and laborious HAC technology has significantly improved and is now closer to clinical studies. In here, we reviewed the achievements in the technology of de novo synthesized HACs for a chromosome transfer for developing gene therapy tissue replacement models of monogenic human diseases.

Applications of bottom-up human artificial chromosomes in cell research and cell engineering

Chromosome manipulation is a useful technique in biological science. We have constructed human artificial chromosomes (HACs) based on the transfection of centromeric alphoid DNA precursors into cultured human cells. Moreover, HAC-based technology has been developed into a novel gene expression vector tool for introducing large-size genomic DNA. This technique provides natural expression, as well as stable expression without the gene silencing that often occurs with conventional vectors in mammalian cells. Here we review the properties of HACs, and issues regarding the use of HAC technology for basic and applied research.

Human Antigen Leucocyte (HLA)-G and HLA-E are differentially expressed in pancreatic disorders

BACKGROUND

Little information is available regarding the expression of the immunomodulatory Human Leukocyte Antigen (HLA)-G and -E molecules in pancreatic disorders.

AIM

To analyze HLA-G and -E expression in specimens of alcoholic chronic pancreatitis (ACP), idiopathic chronic pancreatitis (ICP), type 1 (T1D) and type 2 diabetes (T2D) and in histologically normal pancreas (HNP).

METHODS

HLA-G and -E expression (ACP = 30, ICP = 10, T1D = 10, T2D = 30 and HNP = 20) was evaluated by immunohistochemistry in three different areas (acini, islets and inflammatory infiltrate).

RESULTS

Acini and islets from HNP specimens exhibited higher HLA-G and -E expression compared to corresponding areas from all other patient groups. In inflammatory infiltrate, HLA-G and -E expression was observed only among the pancreatic disorders. We observed higher HLA-G and -E expression in acini from T2D compared to ACP, as well as higher HLA-G expression compared to ICP.

CONCLUSION

The decreased expression of HLA-G and -E in islets and acini together with the expression of these molecules in the inflammatory infiltrating cells were shared features among chronic inflammatory and autoimmune pancreatic disorders evaluated in this study, possibly reflecting tissue damage.

The Autoimmune Regulator (Aire) transactivates HLA-G gene expression in thymic epithelial cells

The Autoimmune Regulator (Aire) protein coordinates the negative selection of developing thymocytes by inducing the expression of hundreds of tissue-specific antigens within the thymic medulla, which is also a primary site of the expression of the immune checkpoint HLA-G molecule. Considering the immunomodulatory properties of Aire and HLA-G, and considering that the role of the constitutive thymus expression of HLA-G has not been elucidated, we studied the effect of AIRE cDNA transfection on HLA-G expression in 4D6 thymic cells and in the HLA-G-positive JEG-3 choriocarcinoma cells. Aire promoted the transactivation of HLA-G gene by increasing the overall transcription, inducing the transcription of at least G1 and G2/G4 isoforms, and incrementing the occurrence and distribution of intracellular HLA-G protein solely in 4D6 thymic cells. Luciferase-based assays and chromatin immunoprecipitation experiments performed in 4D6 cells revealed that Aire targeted at least two regions within the 5'-untranslated regulatory region (5'-URR) extending 1·4 kb from the first ATG initiation codon. The interaction occurs independently of three putative Aire-binding sites. These results indicate that the Aire-induced upregulation of HLA-G in thymic cells is likely to act through the interaction of Aire with specific HLA-G 5'-URR DNA-binding factors. Such a multimeric transcriptional complex might operate in the thymus during the process of promiscuous gene expression.

Coordinated DNA Methylation and Gene Expression Data for Identification of the Critical Genes Associated with Childhood Atopic Asthma

Asthma is a chronic inflammatory disorder of airways that involves in many cells and factors. This study aimed to screen critical genes and miRNAs involved in childhood atopic asthma. DNA methylation and gene expression data (access numbers GSE65163 and GSE65204) were downloaded from Gene Expression Omnibus (GEO) database, which included 72 atopic asthmatic subject samples and 69 healthy samples. The differentially expressed genes (DEGs) with DNA methylation changes were identified, followed by Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Gene coexpression network and miRNA-target gene regulatory networks were then constructed. Besides, we screened critical drug molecules that have high correlation with atopic asthma in children. A total of 146 critical DEGs with DNA methylation changes were screened from atopic asthmatic samples compared with healthy control samples. GO and KEGG pathway enrichment analysis showed that the critical genes were mainly related to 20 GO terms and 13 KEGG pathways. In the coexpression network, tumor necrosis factor (TNF) and major histocompatibility complex, class II, DP alpha 1 (HLA-DPA1) were identified that were significantly related to immune response process. Analysis of miRNA-target gene network showed that hsa-miR-148b had the highest number of target genes(degree = 21). Besides, we found that Alsterpaullone had a correlation value closest to -1 (correlation = -0.884, p = 0.0031), which indicated that the agent might be considered as a potential agent that antagonized to asthma. The dysregulation of TNF, HLA-DPA1, and miR-148b might be related to the immune response of childhood atopic asthma.

High level of soluble human leukocyte antigen (HLA)-G at beginning of pregnancy as predictor of risk of malaria during infancy

Placental malaria has been associated with an immune tolerance phenomenon and a higher susceptibility to malaria infection during infancy. HLA-G is involved in fetal maternal immune tolerance by inhibiting maternal immunity. During infections HLA-G can be involved in immune escape of pathogens by creating a tolerogenic environment. Recent studies have shown an association between the risk of malaria and HLA-G at both genetic and protein levels. Moreover, women with placental malaria have a higher probability of giving birth to children exhibiting high sHLA-G, independently of their own level during pregnancy. Our aim was to explore the association between the level of maternal soluble HLA-G and the risk of malaria infection in their newborns. Here, 400 pregnant women and their children were actively followed-up during 24 months. The results show a significant association between the level of sHLA-G at the first antenatal visit and the time to first malaria infection during infancy adjusted to the risk of exposure to vector bites (aHR = 1.02, 95%CI [1.01–1.03], p = 0.014). The level of sHLA-G is a significant predictor of the occurrence of malaria infection during infancy consistent with the hypothesis that mother sHLA-G could be a biomarker of malaria susceptibility in children.

Pregnancy Immunogenetics and Genomics: Implications for Pregnancy-Related Complications and Autoimmune Disease

Pregnancy presents a singular physiological scenario during which the maternal immune system must accommodate the semiallogeneic fetus. Fluctuations between pro- and anti-inflammatory states are required throughout gestation to facilitate uterine tissue remodeling, fetal growth and development, and finally birth. Tolerance for the fetus must be established and maintained without fundamentally compromising the maternal immune system function, so that both the mother and fetus are protected from foreign insults. Here, we review our current understanding of how genetic variation at both maternal and fetal loci affects implantation and placenta formation, thereby determining the likelihood of a successful pregnancy outcome or the development of pregnancy-related complications. We also consider the impact of pregnancy on both the maternal and fetal systemic immune systems and the related implications for modulating ongoing autoimmune diseases and triggering their development.

Improving the efficiency of gene insertion in a human artificial chromosome vector and its transfer in human-induced pluripotent stem cells

A human artificial chromosome (HAC) vector has potential to overcome the problems of stable gene expression associated with plasmid, transposon, and virus-based vectors, such as insertional mutagenesis, position effect, uncontrollable copy number, unstable gene expression, and DNA size limitation. The main advantages of the HAC are its episomal nature and ability to accommodate DNA inserts of any size. However, HAC vectors have two disadvantages: low efficiency of gene insertion and lack of reports regarding the successful HAC transfer to human-induced pluripotent stem cells (iPSCs). We here provide the first report of a method for the efficient transfer of HAC to human iPSCs for obtaining reproducible experimental results. Moreover, we achieved a 10% increase in the gene insertion efficiency in the HAC vector using our new site-specific recombination systems VCre/VloxP and SCre/SloxP.

HLA-G: At the Interface of Maternal-Fetal Tolerance

During pregnancy, semiallogeneic fetal extravillous trophoblasts (EVT) invade the uterine mucosa without being rejected by the maternal immune system. Several mechanisms were initially proposed by Peter Medawar half a century ago to explain this apparent violation of the laws of transplantation. Then, three decades ago, an unusual human leukocyte antigen (HLA) molecule was identified: HLA-G. Uniquely expressed in EVT, HLA-G has since become the center of the present understanding of fetus-induced immune tolerance. Despite slow progress in the field, the last few years have seen an explosion in our knowledge of HLA-G biology. Here, we critically review new insights into the mechanisms controlling the expression and function of HLA-G at the maternal-fetal interface, and discuss their relevance for fetal tolerance.

Hypoxia inducible factor-1 mediates the expression of the immune checkpoint HLA-G in glioma cells through hypoxia response element located in exon 2

HLA-G is an immune checkpoint molecule with specific relevance in cancer immunotherapy. It was first identified in cytotrophoblasts, protecting the fetus from maternal rejection. HLA-G tissue expression is very restricted but induced in numerous malignant tumors such as glioblastoma, contributing to their immune escape. Hypoxia occurs during placenta and tumor development and was shown to activate HLA-G. We aimed to elucidate the mechanisms of HLA-G activation under conditions combining hypoxia-mimicking treatment and 5-aza-2'deoxycytidine, a DNA demethylating agent used in anti-cancer therapy which also induces HLA-G. Both treatments enhanced the amount of HLA-G mRNA and protein in HLA-G negative U251MG glioma cells. Electrophoretic Mobility Shift Assays and luciferase reporter gene assays revealed that HLA-G upregulation depends on Hypoxia Inducible Factor-1 (HIF-1) and a hypoxia responsive element (HRE) located in exon 2. A polymorphic HRE at -966 bp in the 5'UT region may modulate the magnitude of the response mediated by the exon 2 HRE. We suggest that therapeutic strategies should take into account that HLA-G expression in response to hypoxic tumor environment is dependent on HLA-G gene polymorphism and DNA methylation state at the HLA-G locus.

A distant trophoblast-specific enhancer controls HLA-G expression at the maternal-fetal interface

HLA-G, a nonclassical HLA molecule uniquely expressed in the placenta, is a central component of fetus-induced immune tolerance during pregnancy. The tissue-specific expression of HLA-G, however, remains poorly understood. Here, systematic interrogation of the HLA-G locus using massively parallel reporter assay (MPRA) uncovered a previously unidentified cis-regulatory element 12 kb upstream of HLA-G with enhancer activity, Enhancer L Strikingly, clustered regularly-interspaced short palindromic repeats (CRISPR)/Cas9-mediated deletion of this enhancer resulted in ablation of HLA-G expression in JEG3 cells and in primary human trophoblasts isolated from placenta. RNA-seq analysis demonstrated that Enhancer L specifically controls HLA-G expression. Moreover, DNase-seq and chromatin conformation capture (3C) defined Enhancer L as a cell type-specific enhancer that loops into the HLA-G promoter. Interestingly, MPRA-based saturation mutagenesis of Enhancer L identified motifs for transcription factors of the CEBP and GATA families essential for placentation. These factors associate with Enhancer L and regulate HLA-G expression. Our findings identify long-range chromatin looping mediated by core trophoblast transcription factors as the mechanism controlling tissue-specific HLA-G expression at the maternal-fetal interface. More broadly, these results establish the combination of MPRA and CRISPR/Cas9 deletion as a powerful strategy to investigate human immune gene regulation.

First genome-wide association study in an Australian aboriginal population provides insights into genetic risk factors for body mass index and type 2 diabetes

A body mass index (BMI) >22kg/m² is a risk factor for type 2 diabetes (T2D) in Aboriginal Australians. To identify loci associated with BMI and T2D we undertook a genome-wide association study using 1,075,436 quality-controlled single nucleotide polymorphisms (SNPs) genotyped (Illumina 2.5M Duo Beadchip) in 402 individuals in extended pedigrees from a Western Australian Aboriginal community. Imputation using the thousand genomes (1000G) reference panel extended the analysis to 6,724,284 post quality-control autosomal SNPs. No associations achieved genome-wide significance, commonly accepted as P<5x10^-8. Nevertheless, genes/pathways in common with other ethnicities were identified despite the arrival of Aboriginal people in Australia >45,000 years ago. The top hit (rs10868204 P_genotyped = 1.50x10^-6; rs11140653 P_{imputed_1000G} = 2.90x10^-7) for BMI lies 5’ of NTRK2, the type 2 neurotrophic tyrosine kinase receptor for brain-derived neurotrophic factor (BDNF) that regulates energy balance downstream of melanocortin-4 receptor (MC4R). PIK3C2G (rs12816270 P_genotyped = 8.06x10^-6; rs10841048 P_{imputed_1000G} = 6.28x10^-7) was associated with BMI, but not with T2D as reported elsewhere. BMI also associated with CNTNAP2 (rs6960319 P_genotyped = 4.65x10^-5; rs13225016 P_{imputed_1000G} = 6.57x10^-5), previously identified as the strongest gene-by-environment interaction for BMI in African-Americans. The top hit (rs11240074 P_genotyped = 5.59x10^-6, P_{imputed_1000G} = 5.73x10^-6) for T2D lies 5’ of BCL9 that, along with TCF7L2, promotes beta-catenin’s transcriptional activity in the WNT signaling pathway. Additional hits occurred in genes affecting pancreatic (KCNJ6, KCNA1) and/or GABA (GABRR1, KCNA1) functions. Notable associations observed for genes previously identified at genome-wide significance in other populations included MC4R (P_genotyped = 4.49x10^-4) for BMI and IGF2BP2 P_{imputed_1000G} = 2.55x10^-6) for T2D. Our results may provide novel functional leads in understanding disease pathogenesis in this Australian Aboriginal population.

Generating a transgenic mouse line stably expressing human MHC surface antigen from a HAC carrying multiple genomic BACs

The human artificial chromosome (HAC) vector is a promising tool to improve the problematic suppression and position effects of transgene expression frequently seen in transgenic cells and animals produced by conventional plasmid or viral vectors. We generated transgenic mice maintaining a single HAC vector carrying two genomic bacterial artificial chromosomes (BACs) from human HLA-DR loci (DRA and DRB1). Both transgenes on the HAC in transgenic mice exhibited tissue-specific expression in kidney, liver, lung, spleen, lymph node, bone marrow, and thymus cells in RT-PCR analysis. Stable functional expression of a cell surface HLA-DR marker from both transgenes, DRA and DRB1 on the HAC, was detected by flow cytometric analysis of splenocytes and maintained through at least eight filial generations. These results indicate that the de novo HAC system can allow us to manipulate multiple BAC transgenes with coordinated expression as a surface antigen through the generation of transgenic animals.

The dual role of HLA-G in cancer

We here review the current data on the role of HLA-G in cancer based on recent findings of an unexpected antitumor activity of HLA-G in hematological malignancies. For the past decade, HLA-G has been described as a tumor-escape mechanism favoring cancer progression, and blocking strategies have been proposed to counteract it. Aside from these numerous studies on solid tumors, recent data showed that HLA-G inhibits the proliferation of malignant B cells due to the interaction between HLA-G and its receptor ILT2, which mediates negative signaling on B cell proliferation. These results led to the conjecture that, according to the malignant cell type, HLA-G should be blocked or conversely induced to counteract tumor progression. In this context, we will here present (i) the dual role of HLA-G in solid and liquid tumors with special emphasis on (ii) the HLA-G active structures and their related ILT2 and ILT4 receptors and (iii) the current knowledge on regulatory mechanisms of HLA-G expression in tumors.

Transcriptional and posttranscriptional regulations of the HLA-G gene

HLA-G has a relevant role in immune response regulation. The overall structure of the HLA-G coding region has been maintained during the evolution process, in which most of its variable sites are synonymous mutations or coincide with introns, preserving major functional HLA-G properties. The HLA-G promoter region is different from the classical class I promoters, mainly because (i) it lacks regulatory responsive elements for IFN-γ and NF-κB, (ii) the proximal promoter region (within 200 bases from the first translated ATG) does not mediate transactivation by the principal HLA class I transactivation mechanisms, and (iii) the presence of identified alternative regulatory elements (heat shock, progesterone and hypoxia-responsive elements) and unidentified responsive elements for IL-10, glucocorticoids, and other transcription factors is evident. At least three variable sites in the 3' untranslated region have been studied that may influence HLA-G expression by modifying mRNA stability or microRNA binding sites, including the 14-base pair insertion/deletion, +3142C/G and +3187A/G polymorphisms. Other polymorphic sites have been described, but there are no functional studies on them. The HLA-G coding region polymorphisms might influence isoform production and at least two null alleles with premature stop codons have been described. We reviewed the structure of the HLA-G promoter region and its implication in transcriptional gene control, the structure of the HLA-G 3'UTR and the major actors of the posttranscriptional gene control, and, finally, the presence of regulatory elements in the coding region.