MFEprimer-3.0: quality control for PCR primers.

Quality control (QC) for lab-designed primers is crucial for the success of a polymerase chain reaction (PCR). Here, we present MFEprimer-3.0, a functional primer quality control program for checking non-specific amplicons, dimers, hairpins and other parameters. The new features of the current version include: (i) more sensitive binding site search using the updated k-mer algorithm that allows mismatches within the k-mer, except for the first base at the 3' end. The binding sites of each primer with a stable 3' end are listed in the output; (ii) new algorithms for rapidly identifying self-dimers, cross-dimers and hairpins; (iii) the command-line version, which has an added option of JSON output to enhance the versatility of MFEprimer by acting as a QC step in the 'primer design → quality control → redesign' pipeline; (iv) a function for checking whether the binding sites contain single nucleotide polymorphisms (SNPs), which will affect the consistency of binding efficiency among different samples. In summary, MFEprimer-3.0 is updated with the well-tested PCR primer QC program and it can be integrated into various PCR primer design applications as a QC module. The MFEprimer-3.0 server is freely accessible without any login requirement at: https://mfeprimer3.igenetech.com/ and https://www.mfeprimer.com/. The source code for the command-line version is available upon request.

Association between chromosomal aberration of COX8C and tethered spinal cord syndrome: array-based comparative genomic hybridization analysis.

Copy number variations have been found in patients with neural tube abnormalities. In this study, we performed genome-wide screening using high-resolution array-based comparative genomic hybridization in three children with tethered spinal cord syndrome and two healthy parents. Of eight copy number variations, four were non-polymorphic. These non-polymorphic copy number variations were associated with Angelman and Prader-Willi syndromes, and microcephaly. Gene function enrichment analysis revealed that COX8C, a gene associated with metabolic disorders of the nervous system, was located in the copy number variation region of Patient 1. Our results indicate that array-based comparative genomic hybridization can be used to diagnose tethered spinal cord syndrome. Our results may help determine the pathogenesis of tethered spinal cord syndrome and prevent occurrence of this disease.

Cross-talk between EPAS-1/HIF-2α and PXR signaling pathway regulates multi-drug resistance of stomach cancer cell.

EPAS-1/HIF-2α (Endothelial PAS domain-containing protein 1/hypoxia-inducible transcription factors 2α) is a transcription factor expressed in a wide range of human cancers, including stomach cancer. Although EPAS-1 has been studied for years, its function in oncogenic transformation processes needs to be further investigated. In this study, we found that EPAS-1 would promote the growth of stomach cancer cell line BGC-823. Our results revealed that EPAS-1 interacts with Pregnane X Receptor (PXR), a nuclear receptor that regulates multiple genes' transcription involved in multi-drugs resistance (MDR) process. Protein-protein interaction between EPAS-1 and PXR was identified by co-immunoprecipitation and GST-pull down assays. By this interaction, EPAS-1 recruited PXR to its response elements in promoter/enhancer regions of CYP3A4, a PXR target gene. Over-expression of EPAS-1 increased the expression of PXR responsive genes, enhanced the proliferation of BGC-823 cells and boosted the resistance of BGC-823 cells against the cytotoxicity of chemotherapeutic drugs, e.g. Mitomycin C and Paclitaxel. Reduction of EPAS-1 level via its siRNA disrupted the proliferation, and enhanced the susceptibility of BGC-823 cells to those chemotherapeutic drugs. Our findings suggested that EPAS-1 and PXR may cooperatively participate in development and especially MDR process of stomach cancer. These findings may contribute to more effective targeted drugs discovery for the stomach cancer therapy.

Upregulation of neuroglobin expression and changes in serum redox indices in a rat model of middle cerebral artery occlusion.

Neuroglobin (NGB) is a recently identified protein, which is localized in the neurons and retinal cells of the central and peripheral nervous systems in vertebrates. It is hypothesized to function as a scavenger for reactive oxygen species, or as a stress-responsive sensor for signal transduction in hypoxic-ischemic brain insults. However, the mechanism underlying the physiological function of this protein remains to be elucidated. In the present study, the profiling of changes in the serum redox index of morphological features of the hippocampus and cortex, and of the expression of NGB and hypoxia-inducible factor-1α (HIF-1α), are described in a rat middle cerebral artery occlusion (MCAO) model. The necrotic zone of the rat neural tissues increased in size with increasing reperfusion time, and different brain slices exhibited necrosis in different regions. The number of NGB-positive hippocampal and cortical cells, as well as NGB and HIF-1α transcript and protein levels in the ischemic cortex, increased with increasing reperfusion time. NGB and HIF-1α mRNA and protein levels peaked in the group that received reperfusion at 32 h after MCAO. These findings indicated that HIF-1α may be involved in ischemic pathology in an MCAO model and that NGB expression may be upregulated. Serum superoxide dismutase (SOD) activity decreased and serum malondialdehyde (MDA) levels increased with increasing reperfusion time, indicating that the redox potential increased following MCAO. Serum SOD and MDA measurements may, therefore, be useful as biomarkers for the early detection of ischemic injury in a clinical setting.

MEIS1 functions as a potential AR negative regulator.

The androgen receptor (AR) plays critical roles in human prostate carcinoma progression and transformation. However, the activation of AR is regulated by co-regulators. MEIS1 protein, the homeodomain transcription factor, exhibited a decreased level in poor-prognosis prostate tumors. In this study, we investigated a potential interaction between MEIS1 and AR. We found that overexpression of MEIS1 inhibited the AR transcriptional activity and reduced the expression of AR target gene. A potential protein-protein interaction between AR and MEIS1 was identified by the immunoprecipitation and GST pull-down assays. Furthermore, MEIS1 modulated AR cytoplasm/nucleus translocation and the recruitment to androgen response element in prostate specific antigen (PSA) gene promoter sequences. In addition, MEIS1 promoted the recruitment of NCoR and SMRT in the presence of R1881. Finally, MEIS1 inhibited the proliferation and anchor-independent growth of LNCaP cells. Taken together, our data suggests that MEIS1 functions as a novel AR co-repressor.

Whole exome sequencing identifies mutation of EDNRA involved in ACTH-independent macronodular adrenal hyperplasia.

ACTH independent macronodular adrenal hyperplasia (AIMAH) is a rare disorder characterized by bilateral macronodular hyperplasia of the adrenal glands and increased cortisol production with subclinical or overt Cushing's syndrome. Although the family clustering of AIMAH is infrequent, we have tried our best to find such a familial affected pedigree with complete clinical information and successfully collect adrenalectomy tissue samples from two members of this family. Using whole exome sequencing and several variant prioritization strategies based on disease network analysis, we identified Endothelin receptor type A (EDNRA) Ser420Thr mutation as a causative mutation of AIMAH. EDNRA is a member of G protein coupled receptor family and is involved in cardiovascular or polycystic kidney disease. Our findings indicate that the mutation of EDNRA at S420T site should be regard as a potential AIMAH causative variation in familial and sporadic affected patients.

Genome-wide computational identification of bicistronic mRNA in humans.

Mammalian bicistronic mRNA is a recently discovered mammalian gene structure. Several reported cases of mammalian bicistronic mRNA indicated that genes of this structure play roles in some important biological processes. However, a genome-wide computational identification of bicistronic mRNA in mammalian genome, such as human genome, is still lacking. Here we used a comparative genomics approach to identify the frequency of human bicistronic mRNA. We then validated the result by using a new support vector machine (SVM) model. We identified 43 human bicistronic mRNAs in 30 distinct genes. Our literature analysis shows that our method recovered 100 % (6/6) of the previously known bicistronic mRNAs which had been experimentally confirmed by other groups. Our graph theory-based analysis and GO analysis indicated that human bicistronic mRNAs are prone to produce different yet closely functionally related proteins. In addition, we also described and analyzed three different mechanisms of ORF fusion. Our method of identifying bicistronic mRNAs in human genome provides a model for the computational identification of characteristic gene structures in mammalian genomes. We anticipate that our data will facilitate further molecular characterization and functional study of human bicistronic mRNA.

Sequencing of the first ayu (Plecoglossus altivelis) macrophage transcriptome and microarray development for investigation the effect of LECT2 on macrophages.

Macrophages play an important role in first-line host defense of innate immune in fishes. However, it is difficult to investigate cellular mechanism of immune response in fish species with little genomic information available. Here we present the first use of RNA-Sequencing to study the macrophage transcriptome of ayu, Plecoglossus altivelis, which is an economically important fish in East Asia. De novo assembly generated 49,808 non-redundant consensus sequences, among which 23,490 transcripts found respective coding sequences. 15,707 transcripts are predicted to be involved in known metabolic or signaling pathways. The sequences were then used to develop a microarray for measurement the effect of recombinant LECT2 on ayu macrophages. LECT2 altered expression of a variety of genes mainly implicated in actin cytoskeleton, pattern recognition receptors and cytokines. Meanwhile, LECT2 enhanced phagocytosis, bacterial killing, and respiratory burst in ayu macrophages, which supported the thought derived from the microarray data that LECT2 activates macrophages. In conclusion, our results contribute to understanding the specific regulation mechanism of LECT2 in macrophage activation, and the combination of transcriptome analysis and microarray assay is a good method for screening a special tissue or cell response to a stimulus or pathogen in non-model fish species.

Neuroglobin upregulation offers neuroprotection in traumatic brain injury.

OBJECTIVES: The aim of this study was to investigate rat neuroglobin (rNGB) expression level after traumatic brain injury (TBI) and further study its neuroprotective effects in TBI when it was overexpressed in adenoviral vector. METHODS: The Wistar rats (280-320 g) were divided into control, 12 and 36 hours after TBI groups (n = 3) and their TBI model was established. Subsequently, NGB expression level was examined by Western blot and immunohistochemical. Beyond that, adenoviral vectors pAdEasy-rNGB-GFP and pAdEasy-GFP were constructed and transfected into the rat brain respectively (pAdEasy-GFP was control), and the neuroprotective effects were examined by immunohistochemical. RESULTS: Immunohistochemical and Western blot results demonstrated that NGB expression level was increased at 12 and 36 hours after TBI injury compare with control. Meanwhile, the pAdEasy-rNGB-GFP transfected rats suffered less necrosis and apoptosis compare to control. CONCLUSIONS: NGB was upregulated in TBI and overexpressed rNGB had a significant neuroprotection in TBI. However, the mechanism remained unknown. This study suggested that rNGB overexpression may be a new strategy for treating of TBI.

Neuroprotective effects of neuroglobin after mechanical injury.

Neuroglobin (NGB) is a recently discovered globin, which is widely expressed in vertebrates central and peripheral nervous systems. Previous studies have shown that NGB is important in protecting neurons from hypoxic/ischemic brain injuries. However, there are no reports on the neuroprotective effects of NGB after mechanical injury. Currently, we showed that the NGB expression level in neurons increased continuously from 2 h after injury, and reached a peak at 16 h (p<0.01), after which it decreased sharply. NGB that was overexpressed in mechanically injured B104 cells showed significant neuroprotective effects. Lactate dehydrogenase (LDH) activity decreased and cell survival rates increased (p<0.01, n=5). In the rat model of focal brain trauma, the NGB expression increased sharply at 1 h, after which it increased continuously until it reached a peak at 6 h, and then gradually decreased (p<0.01, n=5). Furthermore, moderate and severe injury resulted in significantly higher NGB levels than did mild injury (p<0.01, n=5). Our results indicate that NGB exerts significant neuroprotective effects after mechanical injury, and thus has important implications for the prognosis and cure of traumatic brain injury.

Reliability analysis of the Ahringer Caenorhabditis elegans RNAi feeding library: a guide for genome-wide screens.

BACKGROUND: The Ahringer C. elegans RNAi feeding library prepared by cloning genomic DNA fragments has been widely used in genome-wide analysis of gene function. However, the library has not been thoroughly validated by direct sequencing, and there are potential errors, including: 1) mis-annotation (the clone with the retired gene name should be remapped to the actual target gene); 2) nonspecific PCR amplification; 3) cross-RNAi; 4) mis-operation such as sample loading error, etc. RESULTS: Here we performed a reliability analysis on the Ahringer C. elegans RNAi feeding library, which contains 16,256 bacterial strains, using a bioinformatics approach. Results demonstrated that most (98.3%) of the bacterial strains in the library are reliable. However, we also found that 2,851 (17.54%) bacterial strains need to be re-annotated even they are reliable. Most of these bacterial strains are the clones having the retired gene names. Besides, 28 strains are grouped into unreliable category and 226 strains are marginal because of probably expressing unrelated double-stranded RNAs (dsRNAs). The accuracy of the prediction was further confirmed by direct sequencing analysis of 496 bacterial strains. Finally, a freely accessible database named CelRNAi (http://biocompute.bmi.ac.cn/CelRNAi/) was developed as a valuable complement resource for the feeding RNAi library by providing the predicted information on all bacterial strains. Moreover, submission of the direct sequencing result or any other annotations for the bacterial strains to the database are allowed and will be integrated into the CelRNAi database to improve the accuracy of the library. In addition, we provide five candidate primer sets for each of the unreliable and marginal bacterial strains for users to construct an alternative vector for their own RNAi studies. CONCLUSIONS: Because of the potential unreliability of the Ahringer C. elegans RNAi feeding library, we strongly suggest the user examine the reliability information of the bacterial strains in the CelRNAi database before performing RNAi experiments, as well as the post-RNAi experiment analysis.

A proteomic view of Caenorhabditis elegans caused by short-term hypoxic stress.

BACKGROUND: The nematode Caenorhabditis elegans is both sensitive and tolerant to hypoxic stress, particularly when the evolutionarily conserved hypoxia response pathway HIF-1/EGL-9/VHL is involved. Hypoxia-induced changes in the expression of a number of genes have been analyzed using whole genome microarrays in C. elegans, but the changes at the protein level in response to hypoxic stress still remain unclear. RESULTS: Here, we utilized a quantitative proteomic approach to evaluate changes in the expression patterns of proteins during the early response to hypoxia in C. elegans. Two-dimensional difference gel electrophoresis (2D-DIGE) was used to compare the proteomic maps of wild type C. elegans strain N2 under a 4-h hypoxia treatment (0.2% oxygen) and under normoxia (control). A subsequent analysis by MALDI-TOF-TOF-MS revealed nineteen protein spots that were differentially expressed. Nine of the protein spots were significantly upregulated, and ten were downregulated upon hypoxic stress. Three of the upregulated proteins were involved in cytoskeletal function (LEV-11, MLC-1, ACT-4), while another three upregulated (ATP-2, ATP-5, VHA-8) were ATP synthases functionally related to energy metabolism. Four ribosomal proteins (RPL-7, RPL-8, RPL-21, RPS-8) were downregulated, indicating a decrease in the level of protein translation upon hypoxic stress. The overexpression of tropomyosin (LEV-11) was further validated by Western blot. In addition, the mutant strain of lev-11(x12) also showed a hypoxia-sensitive phenotype in subsequent analyses, confirming the proteomic findings. CONCLUSIONS: Taken together, our data suggest that altered protein expression, structural protein remodeling, and the reduction of translation might play important roles in the early response to oxygen deprivation in C. elegans, and this information will help broaden our knowledge on the mechanism of hypoxia response.

MPprimer: a program for reliable multiplex PCR primer design.

BACKGROUND: Multiplex PCR, defined as the simultaneous amplification of multiple regions of a DNA template or multiple DNA templates using more than one primer set (comprising a forward primer and a reverse primer) in one tube, has been widely used in diagnostic applications of clinical and environmental microbiology studies. However, primer design for multiplex PCR is still a challenging problem and several factors need to be considered. These problems include mis-priming due to nonspecific binding to non-target DNA templates, primer dimerization, and the inability to separate and purify DNA amplicons with similar electrophoretic mobility. RESULTS: A program named MPprimer was developed to help users for reliable multiplex PCR primer design. It employs the widely used primer design program Primer3 and the primer specificity evaluation program MFEprimer to design and evaluate the candidate primers based on genomic or transcript DNA database, followed by careful examination to avoid primer dimerization. The graph-expanding algorithm derived from the greedy algorithm was used to determine the optimal primer set combinations (PSCs) for multiplex PCR assay. In addition, MPprimer provides a virtual electrophotogram to help users choose the best PSC. The experimental validation from 2x to 5x plex PCR demonstrates the reliability of MPprimer. As another example, MPprimer is able to design the multiplex PCR primers for DMD (dystrophin gene which caused Duchenne Muscular Dystrophy), which has 79 exons, for 20x, 20x, 20x, 14x, and 5x plex PCR reactions in five tubes to detect underlying exon deletions. CONCLUSIONS: MPprimer is a valuable tool for designing specific, non-dimerizing primer set combinations with constrained amplicons size for multiplex PCR assays.

Transcription and splicing regulation in human umbilical vein endothelial cells under hypoxic stress conditions by exon array.

BACKGROUND: The balance between endothelial cell survival and apoptosis during stress is an important cellular process for vessel integrity and vascular homeostasis, and it is also pivotal in angiogenesis during the development of many vascular diseases. However, the underlying molecular mechanisms remain largely unknown. Although both transcription and alternative splicing are important in regulating gene expression in endothelial cells under stress, the regulatory mechanisms underlying this state and their interactions have not yet been studied on a genome-wide basis. RESULTS: Human umbilical vein endothelial cells (HUVECs) were treated with cobalt chloride (CoCl2) both to mimic hypoxia and to induce cell apoptosis and alternative splicing responses. Cell apoptosis rate analysis indicated that HUVECs exposed to 300 microM CoCl2 for 24 hrs were initially counterbalancing apoptosis with cell survival. We therefore used the Affymetrix exon array system to determine genome-wide transcript- and exon-level differential expression. Other than 1583 differentially expressed transcripts, 342 alternatively spliced exons were detected and classified by different splicing types. Sixteen alternatively spliced exons were validated by RT-PCR. Furthermore, direct evidence for the ongoing balance between HUVEC survival and apoptosis was provided by Gene Ontology (GO) and protein function, as well as protein domain and pathway enrichment analyses of the differentially expressed transcripts. Importantly, a novel molecular module, in which the heat shock protein (HSP) families play a significant role, was found to be activated under mimicked hypoxia conditions. In addition, 46% of the transcripts containing stress-modulated exons were differentially expressed, indicating the possibility of combinatorial regulation of transcription and splicing. CONCLUSION: The exon array system effectively profiles gene expression and splicing on the genome-wide scale. Based on this approach, our data suggest that transcription and splicing not only regulate gene expression, but also carry out combinational regulation of the balance between survival and apoptosis of HUVECs under mimicked hypoxia conditions. Since cell survival following the apoptotic challenge is pivotal in angiogenesis during the development of many vascular diseases, our results may advance the knowledge of multilevel gene regulation in endothelial cells under physiological and pathological conditions.

REMAS: a new regression model to identify alternative splicing events from exon array data.

BACKGROUND: Alternative splicing (AS) is an important regulatory mechanism for gene expression and protein diversity in eukaryotes. Previous studies have demonstrated that it can be causative for, or specific to splicing-related diseases. Understanding the regulation of AS will be helpful for diagnostic efforts and drug discoveries on those splicing-related diseases. As a novel exon-centric microarray platform, exon array enables a comprehensive analysis of AS by investigating the expression of known and predicted exons. Identifying of AS events from exon array has raised much attention, however, new and powerful algorithms for exon array data analysis are still absent till now. RESULTS: Here, we considered identifying of AS events in the framework of variable selection and developed a regression method for AS detection (REMAS). Firstly, features of alternatively spliced exons were scaled by reasonably defined variables. Secondly, we designed a hierarchical model which can represent gene structure and transcriptional influence to exons, and the lasso type penalties were introduced in calculation because of huge variable size. Thirdly, an iterative two-step algorithm was developed to select alternatively spliced genes and exons. To avoid negative effects introduced by small sample size, we ranked genes as parameters indicating their AS capabilities in an iterative manner. After that, both simulation and real data evaluation showed that REMAS could efficiently identify potential AS events, some of which had been validated by RT-PCR or supported by literature evidence. CONCLUSION: As a new lasso regression algorithm based on hierarchical model, REMAS has been demonstrated as a reliable and effective method to identify AS events from exon array data.

HUPO BPP pilot study: a proteomics analysis of the mouse brain of different developmental stages.

This study is a part of the HUPO Brain Proteome Project (BPP) pilot study, which aims at obtaining a reliable database of mouse brain proteome, at the comparison of techniques, laboratories, and approaches as well as at preparing subsequent proteome studies of neurologic diseases. The C57/Bl6 mouse brains of three developmental stages at embryonic day 16 (E16), postnatal day 7 (P7), and 8 wk (P56) (n = 5 in each group) were provided by the HUPO BPP executive committee. The whole brain proteins of each animal were individually prepared using 2-DE coupled with PDQuest software analysis. The protein spots representing developmentally related or stably expressed proteins were then prepared with in-gel digestion followed with MALDI-TOF/TOF MS/MS and analyzed using the MASCOT search engines to search the Swiss-Prot or NCBInr database. The 2-DE gel maps of the mouse brains of all of the developmental stages were obtained and submitted to the Data Collection Centre (DCC). The proteins alpha-enolase, stathmin, actin, C14orf166 homolog, 28,000 kDa heat- and acid-stable phosphoprotein, 3-mercaptopyruvate sulfurtransferase and 40 S ribosomal protein S3a were successfully identified. A further Western blotting analysis demonstrated that enolase is a protein up-regulated in the mouse brain from embryonic stage to adult stage. These data are helpful for understanding the proteome changes in the development of the mouse brain.

[Construction of standard human transcript dataset based on RefSeq and human genome sequence database].

The NCBI Reference Sequence (RefSeq) database aimed to provide a biologically non-redundant collection of DNA, RNA, and protein sequences and to promote the research on genes and proteins of human beings and other species. However, because of widely distributed polymorphisms and different quality control of experiments in individual laboratories, there are potential problems need to be identified in the RefSeq database. Regarding which, we herein define the concept, standard transcript, based on the Central Dogmas of Biology that each standard transcript should be perfectly mapped to the standard genomic DNA sequence at the exon level. A large scale analysis for mapping all of the RefSeq records of human being (2005-4-18) to the officially released human genome sequence database (2005-4-20) was further performed using BLAT, Sim4 and a homemade program, EIparser, which was especially designed for this purpose. The standard transcripts based on the RefSeq database were obtained according to the alignment with standard human genome database. There are 9,771 RefSeq records of human being labeled with "NM_" and "NR_" could be perfectly mapped to human genome sequences, while other 10,943 records could be considered as standard transcripts after reasonable revision by comparing with the genome sequences according to all of the three methods. Moreover, the left 203 unrevisable records and 2,676 inconsistent records reported by the above programs could not be considered as standard transcripts and should be checked critically before using because of potential errors in them. Our study has thus provided a reference standard dataset of human beings with high quality for further bioinformatic and experimental analysis such as polymorphism and mutation of human genes. The reference standard dataset based on above criteria could be retrieved from http://biocompute.bmi.ac.cn/transcriptome/index.htm.