Transcriptional and epigenetic regulation of the integrin collagen receptor locus ITGA1-PELO-ITGA2

PSAT1 Promotes Metastasis via p-AKT/SP1/ITGA2 Axis in Estrogen Receptor-Negative Breast Cancer Cell

BACKGROUND

Accumulating evidence indicates that PSAT1 not only reprogrammed metabolic function but also exhibits "moonlighting" functions in promoting tumor malignancy. However, the underlying molecular mechanisms of PSAT1 promoting ER-negative breast cancer cell migration need further investigation.

METHODS

Briefly, the PSAT1 and ITGA2 expression in cells and tissues was detected using qRT-PCR, immunofluorescence staining and western blot assay. The effect of PSAT1 and ITGA2 was verified both in vitro and in vivo. RNA-seq analysis explored a series of differently expressed genes. The regulation between SP1 and ITGA2 was investigated by ChIP analysis.

RESULTS

We reported PSAT1 was highly expressed in ER-breast cancer tissues and tumor cells and positively correlated with metastasis. Moreover, RNA-seq analysis explored a series of differently expressed genes, including ITGA2, in PSAT1 overexpressed cells. Mechanistically, PSAT1 facilitated breast cancer metastasis via the p-AKT/SP1/ITGA2 axis. We further elucidated that PSAT1 promoted the entry of SP1 into the nucleus through the upregulation of p-AKT and confirmed ITGA2 is a target of SP1. In addition, enhanced cell migration was remarkably reversed by ITGA2 depletion or p-AKT inhibitor treatment.

CONCLUSION

This study clarified the mechanism of PSAT1 in promoting ER-negative breast cancer metastasis, which may provide mechanistic clues for attenuating breast cancer metastasis.

Non-coding RNAs (ncRNAs) and multidrug resistance in glioblastoma: Therapeutic challenges and opportunities

Non-coding RNAs (ncRNAs) have been recognized as pivotal regulators of transcriptional and post-transcriptional gene modulation, exerting a profound influence on a diverse array of biological and pathological cascades, including the intricate mechanisms underlying tumorigenesis and the acquisition of drug resistance in neoplastic cells. Glioblastoma (GBM), recognized as the foremost and most aggressive neoplasm originating in the brain, is distinguished by its formidable resistance to the cytotoxic effects of chemotherapeutic agents and ionizing radiation. Recent years have witnessed an escalating interest in comprehending the involvement of ncRNAs, particularly lncRNAs, in GBM chemoresistance. LncRNAs, a subclass of ncRNAs, have been demonstrated as dynamic modulators of gene expression at the epigenetic, transcriptional, and post-transcriptional levels. Disruption in the regulation of lncRNAs has been observed across various human malignancies, including GBM, and has been linked with developing multidrug resistance (MDR) against standard chemotherapeutic agents. The potential of targeting specific ncRNAs or their downstream effectors to surmount chemoresistance is also critically evaluated, specifically focusing on ongoing preclinical and clinical investigations exploring ncRNA-based therapeutic strategies for glioblastoma. Nonetheless, targeting lncRNAs for therapeutic objectives presents hurdles, including overcoming the blood-brain barrier and the brief lifespan of oligonucleotide RNA molecules. Understanding the complex relationship between ncRNAs and the chemoresistance characteristic in glioblastoma provides valuable insights into the fundamental molecular mechanisms. It opens the path for the progression of innovative and effective therapeutic approaches to counter the therapeutic challenges posed by this aggressive brain tumor. This comprehensive review highlights the complex functions of diverse ncRNAs, including miRNAs, circRNAs, and lncRNAs, in mediating glioblastoma's chemoresistance.

Analysis of N-glycosylation protein of Kashin-Beck disease chondrocytes derived from induced pluripotent stem cells based on label-free strategies with LC-MS/MS

We aimed to compare N-glycosylation proteins in Kashin-Beck disease (KBD) chondrocytes and normal chondrocytes derived from induced pluripotent stem cells (iPSCs). KBD and normal iPSCs were reprogrammed from human KBD and normal dermal fibroblasts, respectively. Subsequently, chondrocytes were differentiated from KBD and normal iPSCs separately. Immunofluorescence was utilized to assay the protein markers of iPSCs and chondrocytes. Differential N-glycosylation proteins were screened using label-free strategies with LC-MS/MS. Bioinformatics analyses were utilized to interpret the functions of differential N-glycosylation proteins. Immunofluorescence staining revealed that both KBD-iPSCs and normal-iPSCs strongly expressed pluripotency markers OCT4 and NANOG. Meanwhile, chondrocyte markers collagen II and SOX9 are presented in KBD-iPSC-chondrocytes and normal-iPSC-chondrocytes. We obtained 87 differential N-glycosylation sites which corresponded to 68 differential proteins, which were constructed into 1 cluster. We obtained collagen type I trimer and 9 other biological processes; polysaccharide binding and 9 other molecular functions; regulation of transcription by RNA polymerase II and 9 other cellular components from GO; the Pl3K-Akt signaling pathway and 9 other KEGG pathways; peroxisome and 7 other subcellular locations; and integrin alpha chain, C-terminal cytoplasmic region, conserved site and 9 other classifications of domain annotations, and 2 networks. FGFR3 and LRP1 are expressed at higher levels in KBD-iPSC-chondrocytes, while the expressions of COL2A1, TIMP1, UNC5B, NOG, LEPR, and ITGA1 were down-regulated in KBD-iPSC-chondrocytes. The differential expressions of these N-glycosylation proteins may lead to the abnormal function of KBD chondrocytes.

Role of integrin α2 in methotrexate-induced epithelial-mesenchymal transition in alveolar epithelial A549 cells

Methotrexate (MTX) is widely used to treat various diseases. However, it induces adverse reactions like serious lung injury, including pulmonary fibrosis. Increasing evidence suggests that epithelial-mesenchymal transition (EMT) in injured alveolar epithelium contributes to the development of the pathophysiological state of the lung. We demonstrated that MTX induced EMT in cultured alveolar epithelial cell lines. Integrin-mediated signaling is considered a significant factor in recognizing the EMT process. However, the relationship between MTX-induced EMT and integrin family members is poorly understood. In the present study, we aimed to clarify the role of integrin in MTX-induced EMT in A549 and NCI-H1299 (H1299) cells by focusing on the integrin alpha 2 (ITGA2) subunit, selected based on our microarray analysis. MTX treatment for 72 h significantly increased the mRNA and cell surface expression of ITGA2 in both cell lines. However, this upregulation by MTX was suppressed by co-treatment with SB431542 and folic acid, which are inhibitors of MTX-induced EMT in A549 cells. The mRNA expression levels of EMT-related genes were more affected in the MTX-treated A549 cells with high ITGA2 expression than in those with low ITGA2 expression. Finally, E7820, an ITGA2 inhibitor, suppressed MTX-induced EMT-related phenotypic changes, such as morphology and mRNA and protein expression of α-smooth muscle actin, a representative EMT marker. These findings suggest that ITGA2 may play a key role in MTX-induced EMT in alveolar epithelial cells.

The small-molecule protein ligand interface stabiliser E7820 induces differential cell line specific responses of integrin α2 expression

BACKGROUND

The mechanism of small-molecule stabilised protein-protein interactions is of growing interest in the pharmacological discovery process. A plethora of different substances including the aromatic sulphonamide E7820 have been identified to act by such a mechanism. The process of E7820 induced CAPERα degradation and the resultant transcriptional down regulation of integrin α2 expression has previously been described for a variety of different cell lines and been made responsible for E7820's antiangiogenic activity. Currently the application of E7820 in the treatment of various malignancies including pancreas carcinoma and breast cancer is being investigated in pre-clinical and clinical trials. It has been shown, that integrin α2 deficiency has beneficial effects on bone homeostasis in mice. To transfer E7820 treatment to bone-related pathologies, as non-healing fractures, osteoporosis and bone cancer might therefore be beneficial. However, at present no data is available on the effect of E7820 on osseous cells or skeletal malignancies.

METHODS

Pre-osteoblastic (MC3T3 and Saos-2) cells and endothelial (eEnd2 cells and HUVECs) cells, each of human and murine origin respectively, were investigated. Vitality assay with different concentrations of E7820 were performed. All consecutive experiments were done at a final concentration of 50 ng/ml E7820. The expression and production of integrin α2 and CAPERα were investigated by quantitative real-time PCR and western blotting. Expression of CAPERα splice forms was differentiated by semi-quantitiative reverse transcriptase PCR.

RESULTS

Here we present the first data showing that E7820 can increase integrin α2 expression in the pre-osteoblast MC3T3 cell line whilst also reproducing canonical E7820 activity in HUVECs. We show that the aberrant activity of E7820 in MC3T3 cells is likely due to differential activity of CAPERα at the integrin α2 promoter, rather than due to differential CAPERα degradation or differential expression of CAPERα spliceforms.

CONCLUSION

The results presented here indicate that E7820 may not be suitable to treat certain malignancies of musculoskeletal origin, due to the increase in integrin α2 expression it may induce. Further investigation of the differential functioning of CAPERα and the integrin α2 promoter in cells of various origin would however be necessary to more clearly differentiate between cell lines that will positively respond to E7820 from those that will not.

Evaluation of Extracellular Matrix Composition to Improve Breast Cancer Modeling

The development of resistance to therapy is a significant obstacle to effective therapeutic regimens. Evaluating the effects of oncology drugs in the laboratory setting is limited by the lack of translational models that accurately recapitulate cell-microenvironment interactions present in tumors. Acquisition of resistance to therapy is facilitated, in part, by the composition of the tumor extracellular matrix (ECM), with the primary current in vitro model using collagen I (COL I). Here we seek to identify the prevalence of COL I-enhanced expression in the triple-negative breast cancer (TNBC) subtype. Furthermore, we identify if methods of response to therapy are altered depending on matrix composition. We demonstrated that collagen content varies in patient tumor samples across subtypes, with COL I expression dramatically increased in typically less aggressive estrogen receptor (ER)-positive(ER+)/progesterone receptor (PGR)-positive (PGR+) cancers irrespective of patient age or race. These findings are of significance considering how frequently COL I is implicated in tumor progression. In vitro analyses of ER+ and ER-negative (ER-) cell lines were used to determine the effects of ECM content (collagen I, collagen IV, fibronectin, and laminin) on proliferation, cellular phenotype, and survival. Neither ER+ nor ER- cells demonstrated significant increases in proliferation when cultured on these ECM substrates. ER- cells cultured on these substrates were sensitized to both chemotherapy and targeted therapy. In addition, MDA-MB-231 cells expressed different morphologies, binding affinities, and stiffness across these substrates. We also demonstrated that ECM composition significantly alters transcription of senescence-associated pathways across ER+ and ER- cell lines. Together, these results suggest that complex matrix composites should be incorporated into in vitro tumor models, especially for the drug-resistant TNBC subtype. Impact statement The importance of tumor extracellular matrix (ECM) in disease progression is often inadequately represented in models of breast cancer that rely heavily on collagen I and Matrigel. Through immunohistochemistry analysis of patient breast tumors, we show a wide variation in collagen content based on subtype, specifically a repression of fibril collagens in the receptor negative subtype, irrespective of age and race. We also demonstrated that tumor ECM composition alters cellular elasticity and oncogenic pathway activation demonstrating that physiologically relevant three-dimensional models of breast cancer should include an ECM that is subtype specific.

In vitro protective effects of Paeonia mascula subsp. hellenica callus extract on human keratinocytes

Natural ingredients have been used to improve the state of health in humans. The genus Paeonia has been studied only limited yet it's reported to have many activities such as antioxidant and anti-inflammatory. To this context, here we focused on an endemic Paeonia species in Attica. This study aims to present the development of the Paeonia mascula subsp. hellenica callus extract and its pleiotropic bioactivity on human primary keratinocytes exploring its potential application as an active agent in skin-related products. This extract showed a high scavenging activity with high phenolic content and an interesting metabolic profile. At a molecular level, the study on the transcript accumulation of genes revealed that this extract exhibits in vitro skin-related protection properties by mediating mitochondrial energy, cell proliferation, immune and inflammatory response and positively regulates genes involved in epidermal and in stratum corneum function. Besides, the extract is proven not skin irritant on reconstructed human skin model. These findings indicate that the specific P. mascula subsp. hellenica extract possesses significant in vitro protection activity on human epidermis and provides new insights into its beneficial role in skin confirming that the advent of biotechnology contribution the past few decades.

RNA-seq transcriptome profiling of porcine lung from two pig breeds in response to Mycoplasma hyopneumoniae infection

Background

Mycoplasma hyopneumoniae (Mhp) is the main pathogen causing respiratory disease in the swine industry. Mhp infection rates differ across pig breeds, with Chinese native pig breeds that exhibit high fecundity (e.g., Jiangquhai, Meishan, Erhualian) more sensitive than Duroc, Landrace, and other imported pig breeds. However, the genetic basis of the immune response to Mhp infection in different pig breeds is largely unknown.

Aims

The aims of this study were to determine the relative Mhp susceptibility of the Chinese native Jiangquhai breed compared to the Duroc breed, and identify molecular mechanisms of differentially expressed genes (DEGs) using an RNA-sequencing (RNA-seq) approach.

Methods

Jiangquhai and Duroc pigs were artificially infected with the same Mhp dose. The entire experiment lasted 28 days. Daily weight gain, Mhp-specific antibody levels, and lung lesion scores were measured to evaluate the Mhp infection susceptibility of different breeds. Experimental pigs were slaughtered on the 28th day. Lung tissues were collected for total RNA extraction. RNA-seq was performed to identify DEGs, which were enriched by gene ontology (GO) and the Kyoto Encyclopedia annotation of Genes and Genomes (KEGG) databases. DEGs were validated with real-time quantitative polymerase chain reaction (RT-qPCR).

Results

Infection with the same Mhp dose produced a more serious condition in Jiangquhai pigs than in Duroc pigs. Jiangquhai pigs showed poorer growth, higher Mhp antibody levels, and more serious lung lesions compared with Duroc pigs. RNA-seq identified 2,250 and 3,526 DEGs in lung tissue from Jiangquhai and Duroc pigs, respectively. The two breeds shared 1,669 DEGs, which were involved in immune-relevant pathways including cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, and chemokine signaling pathway. Compared to Jiangquhai pigs, more chemokines, interferon response factors, and interleukins were specifically activated in Duroc pigs; CXCL10, CCL4, IL6 and IFNG genes were significantly up-regulated, which may help Duroc pigs enhance immune response and reduce Mhp susceptibility.

Conclusion

This study demonstrated differential immune-related DEGs in lung tissue from the two breeds, and revealed an important role of genetics in the immune response to Mhp infection. The biological functions of these important DEGs should be further confirmed and maybe applied as molecular markers that improve pig health.

Evidence of epigenetic alterations in thrombosis and coagulation: A systematic review

Thrombosis in the context of Cardiovascular disease (CVD) affects mainly the blood vessels supplying the heart, brain and peripheries and it is the leading cause of death worldwide. The pathophysiological thrombotic mechanisms are largely unknown. Heritability contributes to a 30% of the incidence of CVD. The remaining variation can be explained by life style factors such as smoking, dietary and exercise habits, environmental exposure to toxins, and drug usage and other comorbidities. Epigenetic variation can be acquired or inherited and constitutes an interaction between genes and the environment. Epigenetics have been implicated in atherosclerosis, ischemia/reperfusion damage and the cardiovascular response to hypoxia. Epigenetic regulators of gene expression are mainly the methylation of CpG islands, histone post translational modifications (PTMs) and microRNAs (miRNAs). These epigenetic regulators control gene expression either through activation or silencing. Epigenetic control is mostly dynamic and can potentially be manipulated to prevent or reverse the uncontrolled expression of genes, a trait that renders them putative therapeutic targets. In the current review, we systematically studied and present available data on epigenetic alterations implicated in thrombosis derived from human studies. Evidence of epigenetic alterations is observed in several thrombotic diseases such as Coronary Artery Disease and Cerebrovascular Disease, Preeclampsia and Antiphospholipid Syndrome. Differential CpG methylation and specific histone PTMs that control transcription of prothrombotic and proinflammatory genes have also been associated with predisposing factors of thrombosis and CVD, such us smoking, air pollution, hypertriglyceridemia, occupational exposure to particulate matter and comorbidities including cancer, Chronic Obstructive Pulmonary Disease and Chronic Kidney Disease. These clinical observations are further supported by in vitro experiments and indicate that epigenetic regulation affects the pathophysiology of thrombotic disorders with potential diagnostic or therapeutic utility.

Regulation and functions of integrin α2 in cell adhesion and disease

Integrins are cell adhesion molecules that are composed of an alpha (α) subunit and a beta (β) subunit with affinity for different extracellular membrane components. The integrin family includes 24 known members that actively regulate cellular growth, differentiation, and apoptosis. Each integrin heterodimer has a particular function in defined contexts as well as some partially overlapping features with other members in the family. As many reviews have covered the general integrin family in molecular and cellular studies in life science, this review will focus on the specific regulation, function, and signaling of integrin α2 subunit (CD49b, VLA-2; encoded by the gene ITGA2) in partnership with β1 (CD29) subunit in normal and cancer cells. Its roles in cell adhesion, cell motility, angiogenesis, stemness, and immune/blood cell regulations are discussed. The pivotal role of integrin α2 in many diseases such as cancer suggests its potential to be used as a novel therapeutic target.

Elucidating the role of plexin D1 in body fat distribution and susceptibility to metabolic disease using a zebrafish model system

Non-communicable diseases (NCDs) such as cardiovascular disease, diabetes and cancer were responsible for 68% of all deaths worldwide in 2012. The regional distribution of lipid deposited within adipose tissue (AT) - so called body fat distribution (BFD) - is a strong risk factor for NCDs. BFD is highly heritable; however, the genetic basis of BFD is almost entirely unknown. Genome-wide association studies have identified several loci associated with BFD, including at Plexin D1 (PLXND1) - a gene known to modulate angiogenesis. We recently demonstrated that zebrafish homozygous for a null mutation in plxnd1 had a reduced capacity to store lipid in visceral AT (VAT) leading to altered BFD. Moreover, we found that type V collagens were upregulated in plxnd1 mutants, and mediated the inhibitory effect of Plxnd1 on VAT growth. These results strengthen evidence that Plxnd1 influences BFD in human populations, and validate zebrafish as a model to study BFD. However, many pertinent questions remain unanswered. Here we outline potential Plxnd1 mechanisms of action in AT, and describe the genetic architecture at human PLXND1 that is associated with BFD and NCD susceptibility.

Integrin α1β1 expression is controlled by c-MYC in colorectal cancer cells

The α1β1 collagen receptor is only present in a few epithelial cell types. In the intestine, it is specifically expressed in proliferating crypt cells. This integrin has been reported to be involved in various cancers where it mediates the downstream activation of the Ras/ERK proliferative pathway. We have recently shown that integrin α1β1 is present in two-thirds of colon adenocarcinomas, but the mechanism by which ITGA1 expression is regulated is not known. DNA methylation, involved in ITGA1 repression during megakaryocyte differentiation, is not the mechanism of ITGA1 regulation in colorectal cancer cells. Our in silico analysis of the ITGA1 promoter revealed two response elements for MYC, an oncogenic factor known to regulate cancer cell proliferation, invasion and migration. In situ, the expressions of both MYC and ITGA1 are localized in the lower crypt of the normal colon and correlate in 72% of the 65 analyzed colorectal cancers. MYC pharmacological inhibition or downregulation of expression with short hairpin RNA in HT29, T84 and SW480 cells resulted in reduced ITGA1 expression at both the transcript and protein levels. Chromatin immunoprecipitation assays revealed that MYC was bound to the chromatin region of the ITGA1 proximal promoter, whereas MYC overexpression enhanced ITGA1 promoter activity that was reduced with MAD co-transfection or by the disruption of the response elements. We concluded that MYC is a key regulating factor for the control of ITGA1 expression.

Rho/MRTF-A-Induced Integrin Expression Regulates Angiogenesis in Differentiated Multipotent Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are known to undergo endothelial differentiation in response to treatment with vascular endothelial growth factor (VEGF), but their angiogenic ability is poorly characterized. In the present study, we aimed to further investigate the role of Rho/MRTF-A in angiogenesis by MSCs and the effect of the Rho/MRTF-A pathway on the expression of integrins α1β1 and α5β1, which are known to mediate physiological and pathological angiogenesis. Our results showed that increased expression of α1, α5, and β1 was observed during angiogenesis of differentiated MSCs, and the Rho/MRTF-A signaling pathway was demonstrated to be involved in regulating the expression of integrins α1, α5, and β1. Luciferase reporter assay and ChIP assay determined that MRTF-A could bind to and transactivate the integrin α1 and α5 promoters. Treatment with the Rho inhibitor C3 transferase, the Rho-associated protein kinase (ROCK) inhibitor Y27632 or with shMRTF-A inhibited both the upregulation of α1, α5, and β1 as well as angiogenesis. Furthermore, in human umbilical vein endothelial cells (HUVECs), MRTF-A deletion led to marked reductions in cell migration and vessel network formation compared with the control. These data demonstrate that Rho/MRTF-A signaling is an important mediator that controls integrin gene expression during MSC-mediated angiogenic processes.

Integrin α1β1

Integrin α1β1 is widely expressed in mesenchyme and the immune system, as well as a minority of epithelial tissues. Signaling through α1 contributes to the regulation of extracellular matrix composition, in addition to supplying in some tissues a proliferative and survival signal that appears to be unique among the collagen binding integrins. α1 provides a tissue retention function for cells of the immune system including monocytes and T cells, where it also contributes to their long-term survival, providing for peripheral T cell memory, and contributing to diseases of autoimmunity. The viability of α1 null mice, as well as the generation of therapeutic monoclonal antibodies against this molecule, have enabled studies of the role of α1 in a wide range of pathophysiological circumstances. The immune functions of α1 make it a rational therapeutic target.

Extra-cellular matrix suppresses expression of the apoptosis mediator Fas by epigenetic DNA methylation

The extracellular matrix (ECM) of bone consists mainly of collagen type I, which induces osteoblastic differentiation and prevents apoptosis. Fas induces apoptosis in cells improperly adhering to ECM. Recently, it was described that Fas expression is modulated by epigenetic DNA methylation. Mouse MC3T3-E1 pre-osteoblastic cells were cultured either on collagen coated or on uncoated culture dishes for control. mRNA was isolated and gene expression was analyzed by quantitative RT-PCR. Furthermore, we measured global and specific DNA methylation. Compared to controls, cells cultured on collagen-coated dishes increased the expression of Runx2 and OCN indicating differentiation of pre-osteoblastic cells. Additionally, collagen up-regulated cyclin-A2 and down-regulated Fas expression suggesting increased cell multiplication. Furthermore, the expression of Dnmt1 and Hells, key mediators of the DNA-methylation process, was increased. As a consequence, we demonstrate that global DNA methylation and specific methylation of the Fas promoter was higher in MC3T3-E1 cells cultured on collagen when compared to controls. Investigation of signal transduction pathways by mean of inhibitors suggests that focal adhesion kinase, MAP- and Jun-kinases and AP-1 are involved in this process. In summary, we demonstrate that ECM prevents activation of Fas by epigenetic DNA-methylation.

Gene profiling of the erythro- and megakaryoblastic leukaemias induced by the Graffi murine retrovirus

Background

Acute erythro- and megakaryoblastic leukaemias are associated with very poor prognoses and the mechanism of blastic transformation is insufficiently elucidated. The murine Graffi leukaemia retrovirus induces erythro- and megakaryoblastic leukaemias when inoculated into NFS mice and represents a good model to study these leukaemias.

Methods

To expand our understanding of genes specific to these leukaemias, we compared gene expression profiles, measured by microarray and RT-PCR, of all leukaemia types induced by this virus.

Results

The transcriptome level changes, present between the different leukaemias, led to the identification of specific cancerous signatures. We reported numerous genes that may be potential oncogenes, may have a function related to erythropoiesis or megakaryopoiesis or have a poorly elucidated physiological role. The expression pattern of these genes has been further tested by RT-PCR in different samples, in a Friend erythroleukaemic model and in human leukaemic cell lines.

We also screened the megakaryoblastic leukaemias for viral integrations and identified genes targeted by these integrations and potentially implicated in the onset of the disease.

Conclusions

Taken as a whole, the data obtained from this global gene profiling experiment have provided a detailed characterization of Graffi virus induced erythro- and megakaryoblastic leukaemias with many genes reported specific to the transcriptome of these leukaemias for the first time.

Enhanced binding of poly(ADP-ribose)polymerase-1 and Ku80/70 to the ITGA2 promoter via an extended cytosine-adenosine repeat

Background

We have identified a cytosine-adenosine (CA) repeat length polymorphism in the 5′-regulatory region of the human integrin α2 gene ITGA2 that begins at −605. Our objective was to establish the contribution of this polymorphism to the regulation of integrin α2β1 expression, which is known to vary several-fold among normal individuals, and to investigate the underlying mechanism(s).

Methodology/Principal Findings

In combination with the SNP C-52T, previously identified by us as a binding site for the transcription factor Sp1, four ITGA2 haplotypes can be distinguished, in the order in which they enhance ITGA2 transcription: (CA)₁₂/-52C>(CA)₁₁/-52C>(CA)₁₁/-52T>(CA)₁₀/-52T. By DNA affinity chromatography and chromatin immunoprecipitation (ChIP) assays, we show that poly (ADP-ribose)polymerase-1 (PARP-1) and Ku80/70 bind specifically and with enhanced affinity to the longer (CA)₁₂ repeat alleles.

Conclusions/Significance

The increased binding of PARP-1 and Ku80/70, known components of transcription co-activator complexes, to the longer (CA)₁₂ alleles of ITGA2 coincides with enhanced α2β1 expression. The most likely explanation for these findings is that PARP-1 and Ku80/70 contribute to the transcriptional regulation of ITGA2. These observations provide new insight into the mechanisms(s) underlying haplotype-dependent variability in integrin α2β1 expression in human platelets and other cells.

Genome-wide association study of anthropometric traits in Korcula Island, Croatia

AIM

To identify genetic variants underlying six anthropometric traits: body height, body weight, body mass index, brachial circumference, waist circumference, and hip circumference, using a genome-wide association study.

METHODS

The study was carried out in the isolated population of the island of Korcula, Croatia, with 898 adult examinees who participated in the larger DNA-based genetic epidemiological study in 2007. Anthropometric measurements followed standard internationally accepted procedures. Examinees were genotyped using HumanHap 370CNV chip by Illumina, with a genome-wide scan containing 316730 single nucleotide polymorphisms (SNP).

RESULTS

A total of 11 SNPs were associated with the investigated traits at the level of P<10(-5), with one SNP (rs7792939 in gene zinc finger protein 498, ZNF498) associated with body weight, hip circumference, and brachial circumference (P=3.59-5.73 x 10(-6)), and another one (rs157350 in gene delta-sarcoglycan, SGCD) with both brachial and hip circumference (P=3.70-6.08 x 10(-6). Variants in CRIM1, a gene regulating delivery of bone morphogenetic proteins to the cell surface, and ITGA1, involved in the regulation of mesenchymal stem cell proliferation and cartilage production, were also associated with brachial circumference (P=7.82 and 9.68 x 10(-6), respectively) and represent interesting functional candidates. Other associations involved those between genes SEZ6L2 and MAX and waist circumference, XTP6 and brachial circumference, and AMPA1/GRIA1 and height.

CONCLUSION

Although the study was underpowered for the reported associations to reach formal threshold of genome-wide significance under the assumption of independent multiple testing, the consistency of association between the 2 variants and a set of anthropometric traits makes CRIM1 and ITGA1 highly interesting for further replication and functional follow-up. Increased linkage disequilibrium between the used markers in an isolated population makes the formal significance threshold overly stringent, and changed allele frequencies in isolate population may contribute to identifying variants that would not be easily identified in large outbred populations.

Designating eukaryotic orthology via processed transcription units

Orthology is a widely used concept in comparative and evolutionary genomics. In addition to prokaryotic orthology, delineating eukaryotic orthology has provided insight into the evolution of higher organisms. Indeed, many eukaryotic ortholog databases have been established for this purpose. However, unlike prokaryotes, alternative splicing (AS) has hampered eukaryotic orthology assignments. Therefore, existing databases likely contain ambiguous eukaryotic ortholog relationships and possibly misclassify alternatively spliced protein isoforms as in-paralogs, which are duplicated genes that arise following speciation. Here, we propose a new approach for designating eukaryotic orthology using processed transcription units, and we present an orthology database prototype using the human and mouse genomes. Currently existing programs cover less than 69% of the human reference sequences when assigning human/mouse orthologs. In contrast, our method encompasses up to 80% of the human reference sequences. Moreover, the ortholog database presented herein is more than 92% consistent with the existing databases. In addition to managing AS, this approach is capable of identifying orthologs of embedded genes and fusion genes using syntenic evidence. In summary, this new approach is sensitive, specific and can generate a more comprehensive and accurate compilation of eukaryotic orthologs.