A constitutive super-enhancer: homologous region 3 of Bombyx mori nucleopolyhedrovirus

Identification of potential pathogenic hepatic super-enhancers regulatory network in high-fat diet induced hyperlipidemia

Hyperlipidemia (HLP) is a prevalent metabolic disorder and a significant risk factor for cardiovascular disease. According to recent discoveries, super-enhancers (SEs) play a role in the increased expression of genes that encode important regulators of both cellular identity and the progression of diseases. However, the underlying function of SEs in the development of HLP is still unknown. We performed an integrative analysis of data on H3K27ac ChIP-seq and RNA sequencing obtained from liver tissues of mice under a low-fat diet (LFD) and high-fat diet (HFD) from GEO database. The rank ordering of super enhancers algorithm was employed for the computation and identification of SEs. A total of 1,877 and 1,847 SEs were identified in the LFD and HFD groups, respectively. The SE inhibitor JQ1 was able to potently reverse lipid deposition and the increased intracellular triglyceride and total cholesterol induced by oleic acid, indicating that SEs are involved in regulating lipid accumulation. Two hundred seventy-eight were considered as HFD-specific SEs (HSEs). GO and KEGG pathway enrichment analysis of the upregulated HSEs-associated genes revealed that they were mainly involved in lipid metabolic pathway. Four hub genes, namely Cd36, Pex11a, Ech1, and Cidec, were identified in the HSEs-associated protein-protein interaction network, and validated with two other datasets. Finally, we constructed a HSEs-specific regulatory network with Cidec and Cd36 as the core through the prediction and verification of transcription factors. Our study constructed a HSEs-associated regulatory network in the pathogenesis of HLP, providing new ideas for the underlying mechanisms and therapeutic targets of HLP.

Spinal-Specific Super Enhancer in Neuropathic Pain

Dysfunctional gene expression in nociceptive pathways plays a critical role in the development and maintenance of neuropathic pain. Super enhancers (SEs), composed of a large cluster of transcriptional enhancers, are emerging as new players in the regulation of gene expression. However, whether SEs participate in nociceptive responses remains unknown. Here, we report a spinal-specific SE (SS-SE) that regulates chronic constriction injury (CCI)-induced neuropathic pain by driving Ntmt1 and Prrx2 transcription in dorsal horn neurons. Peripheral nerve injury significantly enhanced the activity of SS-SE and increased the expression of NTMT1 and PRRX2 in the dorsal horn of male mice in a bromodomain-containing protein 4 (BRD4)-dependent manner. Both intrathecal administration of a pharmacological BRD4 inhibitor JQ1 and CRISPR-Cas9-mediated SE deletion abolished the increased NTMT1 and PRRX2 in CCI mice and attenuated their nociceptive hypersensitivities. Furthermore, knocking down Ntmt1 or Prrx2 with siRNA suppressed the injury-induced elevation of phosphorylated extracellular-signal-regulated kinase (p-ERK) and glial fibrillary acidic protein (GFAP) expression in the dorsal horn and alleviated neuropathic pain behaviors. Mimicking the increase in spinal Ntmt1 or Prrx2 in naive mice increased p-ERK and GFAP expression and led to the genesis of neuropathic pain-like behavior. These results redefine our understanding of the regulation of pain-related genes and demonstrate that BRD4-driven increases in SS-SE activity is responsible for the genesis of neuropathic pain through the governance of NTMT1 and PRRX2 expression in dorsal horn neurons. Our findings highlight the therapeutic potential of BRD4 inhibitors for the treatment of neuropathic pain.SIGNIFICANCE STATEMENT SEs drive gene expression by recruiting master transcription factors, cofactors, and RNA polymerase, but their role in the development of neuropathic pain remains unknown. Here, we report that the activity of an SS-SE, located upstream of the genes Ntmt1 and Prrx2, was elevated in the dorsal horn of mice with neuropathic pain. SS-SE contributes to the genesis of neuropathic pain by driving expression of Ntmt1 and Prrx2 Both inhibition of SS-SE with a pharmacological BRD4 inhibitor and genetic deletion of SS-SE attenuated pain hypersensitivities. This study suggests an effective and novel therapeutic strategy for neuropathic pain.

A Study on the Effect of Energy on the Development of Silkworm Embryos Using an Estrogen-Related Receptor

Energy metabolism is a fundamental process in all organisms. During silkworm (Bombyx mori) embryonic development, there is a high demand for energy due to continuous cell proliferation and differentiation. Estrogen-related receptors (ERRs) are transcriptional regulatory factors that play crucial roles in mammalian energy storage and expenditure. Although most insects have one ERR gene, it also participates in the regulation of energy metabolism, including carbohydrate metabolism in Drosophila, Aphid, and Silkworm. However, no study has reported the direct impact of energy metabolism on embryonic development in silkworms. In this study, we used transgenic technology to increase silkworm (B. mori; Bm) BmERR expression during embryonic development and explored the impact of energy on embryonic development. We found no significant change in the quality of silkworm eggs compared to that of wild-type silkworms. However, there was an increase in the consumption of vitellin, a major nutrient in embryos. This resulted in a decrease in glucose content and a significant increase in ATP content. These findings provide evidence that the acceleration of energy metabolism promotes embryonic development and enhances the motility of hatched silkworms. In addition, these results provide a novel perspective on the relationship between energy metabolism and embryonic development in other insects.

Effect of CDK7 inhibitor on MYCN-amplified retinoblastoma

Retinoblastoma (RB) is a common malignancy that primarily affects pediatric populations. Although a well-known cause of RB is RB1 mutation, MYCN amplification can also lead to the disease, which is a poor prognosis factor. Studies conducted in various tumor types have shown that MYCN inhibition is an effective approach to impede tumor growth. Various indirect approaches have been developed to overcome the difficulty of directly targeting MYCN, such as modulating the super enhancer (SE) upstream of MYCN. The drug used in this study to treat MYCN-amplified RB was THZ1, a CDK7 inhibitor that can effectively suppress transcription by interfering with the activity of SEs. The study findings confirmed the anticancer activity of THZ1 against RB in both in vitro and in vivo experiments. Therapy with THZ1 was found to affect numerous genes in RB according to the RNA-seq analysis. Moreover, the gene expression changes induced by THZ1 treatment were enriched in ribosome, endocytosis, cell cycle, apoptosis, etc. Furthermore, the combined analysis of ChIP-Seq and RNA-seq data suggested a potential role of SEs in regulating the expression of critical transcription factors, such as MYCN, OTX2, and SOX4. Moreover, ChIP-qPCR experiments were conducted to confirm the interaction between MYCN and SEs. In conclusion, THZ1 caused substantial changes in gene transcription in RB, resulting in inhibited cell proliferation, interference with the cell cycle, and increased apoptosis. The efficacy of THZ1 is positively correlated with the degree of MYCN amplification and is likely exerted by interfering with MYCN upstream SEs.

Super-enhancers complexes zoom in transcription in cancer

Super-enhancers (SEs) consist of multiple typical enhancers enriched at high density with transcription factors, histone-modifying enzymes and cofactors. Oncogenic SEs promote tumorigenesis and malignancy by altering protein-coding gene expression and noncoding regulatory element function. Therefore, they play central roles in the treatment of cancer. Here, we review the structural characteristics, organization, identification, and functions of SEs and the underlying molecular mechanism by which SEs drive oncogenic transcription in tumor cells. We then summarize abnormal SE complexes, SE-driven coding genes, and noncoding RNAs involved in tumor development. In summary, we believe that SEs show great potential as biomarkers and therapeutic targets.

Experimental Validation and Prediction of Super-Enhancers: Advances and Challenges

Super-enhancers (SEs) are cis-regulatory elements of the human genome that have been widely discussed since the discovery and origin of the term. Super-enhancers have been shown to be strongly associated with the expression of genes crucial for cell differentiation, cell stability maintenance, and tumorigenesis. Our goal was to systematize research studies dedicated to the investigation of structure and functions of super-enhancers as well as to define further perspectives of the field in various applications, such as drug development and clinical use. We overviewed the fundamental studies which provided experimental data on various pathologies and their associations with particular super-enhancers. The analysis of mainstream approaches for SE search and prediction allowed us to accumulate existing data and propose directions for further algorithmic improvements of SEs' reliability levels and efficiency. Thus, here we provide the description of the most robust algorithms such as ROSE, imPROSE, and DEEPSEN and suggest their further use for various research and development tasks. The most promising research direction, which is based on topic and number of published studies, are cancer-associated super-enhancers and prospective SE-targeted therapy strategies, most of which are discussed in this review.

A review of alternative promoters for optimal recombinant protein expression in baculovirus-infected insect cells

Generating recombinant proteins in insect cells has been made possible via the use of the Baculovirus Expression Vector System (BEVS). Despite the success of many proteins via this platform, some targets remain a challenge due to issues such as cytopathic effects, the unpredictable nature of co-infection and co-expressions, and baculovirus genome instability. Many promoters have been assayed for the purpose of expressing diverse proteins in insect cells, and yet there remains a lack of implementation of those results when reviewing the landscape of commercially available baculovirus vectors. In advancing the platform to produce a greater variety of proteins and complexes, the development of such constructs cannot be avoided. A better understanding of viral gene regulation and promoter options including viral, synthetic, and insect-derived promoters will be beneficial to researchers looking to utilize BEVS by recruiting these intricate mechanisms of gene regulation for heterologous gene expression. Here we summarize some of the developments that could be utilized to improve the expression of recombinant proteins and multi-protein complexes in insect cells.

Super-enhancer-mediated core regulatory circuitry in human cancer

Super-enhancers (SEs) are congregated enhancer clusters with high level of loading of transcription factors (TFs), cofactors and epigenetic modifications. Through direct co-occupancy at their own SEs as well as each other's, a small set of so called "master" TFs form interconnected core regulatory circuitry (CRCs) to orchestrate transcriptional programs in both normal and malignant cells. These master TFs can be predicted mathematically using epigenomic methods. In this Review, we summarize the identification of SEs and CRCs in cancer cells, the mechanisms by which master TFs and SEs cooperatively regulate cancer-type-specific expression programs, and the cancer-type- and subtype-specificity of CRC and the significance in cancer biology.

EphA2 super-enhancer promotes tumor progression by recruiting FOSL2 and TCF7L2 to activate the target gene EphA2

Super-enhancers or stretch enhancers (SEs) consist of large clusters of active transcription enhancers which promote the expression of critical genes that define cell identity during development and disease. However, the role of many super-enhancers in tumor cells remains unclear. This study aims to explore the function and mechanism of a new super-enhancer in various tumor cells. A new super-enhancer that exists in a variety of tumors named EphA2-Super-enhancer (EphA2-SE) was found using multiple databases and further identified. CRISPR/Cas9-mediated deletion of EphA2-SE results in the significant downregulation of its target gene EphA2. Mechanistically, we revealed that the core active region of EphA2-SE comprises E1 component enhancer, which recruits TCF7L2 and FOSL2 transcription factors to drive the expression of EphA2, induce cell proliferation and metastasis. Bioinformatics analysis of RNA-seq data and functional experiments in vitro illustrated that EphA2-SE deletion inhibited cell growth and metastasis by blocking PI3K/AKT and Wnt/β-catenin pathway in HeLa, HCT-116 and MCF-7 cells. Overexpression of EphA2 in EphA2-SE-/- clones rescued the effect of EphA2-SE deletion on proliferation and metastasis. Subsequent xenograft animal model revealed that EphA2-SE deletion suppressed tumor proliferation and survival in vivo. Taken together, these findings demonstrate that EphA2-SE plays an oncogenic role and promotes tumor progression in various tumors by recruiting FOSL2 and TCF7L2 to drive the expression of oncogene EphA2.

Super-enhancers in transcriptional regulation and genome organization

Gene expression is precisely controlled in a stage and cell-type-specific manner, largely through the interaction between cis-regulatory elements and their associated trans-acting factors. Where these components aggregate in promoters and enhancers, they are able to cooperate to modulate chromatin structure and support the engagement in long-range 3D superstructures that shape the dynamics of a cell's genomic architecture. Recently, the term 'super-enhancer' has been introduced to describe a hyper-active regulatory domain comprising a complex array of sequence elements that work together to control the key gene networks involved in cell identity. Here, we survey the unique characteristics of super-enhancers compared to other enhancer types and summarize the recent advances in our understanding of their biological role in gene regulation. In particular, we discuss their capacity to attract the formation of phase-separated condensates, and capacity to generate three-dimensional genome structures that precisely activate their target genes. We also propose a multi-stage transition model to explain the evolutionary pressure driving the development of super-enhancers in complex organisms, and highlight the potential for involvement in tumorigenesis. Finally, we discuss more broadly the role of super-enhancers in human health disorders and related potential in therapeutic interventions.

A super-enhancer controls TGF- β signaling in pancreatic cancer through downregulation of TGFBR2

Pancreatic cancer is one of the most lethal malignant tumors due to a late diagnosis and highly invasion and metastasis. Transforming growth factor-β (TGF-β) signaling plays a vital role in the progression of pancreatic cancer. The delicate activity of TGF-β signaling is particular important for the development of aggression and metastasis which must be fine-tuned. Here, we investigated the role of super-enhancers in regulating the expression of TGF-β signaling pathway in pancreatic cancer. TGFBR2 owns the modification of H3K27Ac around the gene in pancreatic cancer cells. Inhibition of BRD4 by JQ1 robustly blocked the expression of TGFBR2 in a dose dependent manner. We successfully mapped a super-enhancer in TGFBR2 by sgRNA. Deletion of the super-enhancer in TGFBR2 (sgTGFBR2-SEΔ) significantly reduced the expression of TGFBR2 in pancreatic cancer cells. TGF-β-induced p-SMAD2/3 was greatly impaired in TGFBR2 super-enhancer deleted cells. Both migration and EMT induced by TGF-β in pancreatic cancer cells were impaired after deleting the super-enhancer of TGFBR2. Our data suggest a novel molecular mechanism by which a super-enhancer regulates TGFBR2, affecting the activity of TGF-β as well as its function in pancreatic cancer progression.

SEA: a super-enhancer archive

Super-enhancers are large clusters of transcriptional enhancers regarded as having essential roles in driving the expression of genes that control cell identity during development and tumorigenesis. The construction of a genome-wide super-enhancer database is urgently needed to better understand super-enhancer-directed gene expression regulation for a given biology process. Here, we present a specifically designed web-accessible database, Super-Enhancer Archive (SEA, http://sea.edbc.org). SEA focuses on integrating super-enhancers in multiple species and annotating their potential roles in the regulation of cell identity gene expression. The current release of SEA incorporates 83 996 super-enhancers computationally or experimentally identified in 134 cell types/tissues/diseases, including human (75 439, three of which were experimentally identified), mouse (5879, five of which were experimentally identified), Drosophila melanogaster (1774) and Caenorhabditis elegans (904). To facilitate data extraction, SEA supports multiple search options, including species, genome location, gene name, cell type/tissue and super-enhancer name. The response provides detailed (epi)genetic information, incorporating cell type specificity, nearby genes, transcriptional factor binding sites, CRISPR/Cas9 target sites, evolutionary conservation, SNPs, H3K27ac, DNA methylation, gene expression and TF ChIP-seq data. Moreover, analytical tools and a genome browser were developed for users to explore super-enhancers and their roles in defining cell identity and disease processes in depth.

Activation of cAMP-response element-binding protein is positively regulated by PKA and calcium-sensitive calcineurin and negatively by PKC in insect

The cAMP response element binding protein, CREB, is a G protein-coupled receptor (GPCR) signal-activated transcription factor implicated in the control of many biological processes. In the current study, we constructed a cAMP response element (CRE)-driven luciferase assay system for GPCR characterization in insect cells. Our results indicated that Gs-coupled Bombyx adipokinetic hormone receptor (AKHR) and corazonin receptor could effectively initiate CRE-driven luciferase transcription, but forskolin, a reagent widely used to activate adenylyl cyclase in mammalian systems, failed to induce luciferase activity in insect cells co-transfected with a CRE-driven reporter construct upon agonist treatment. Further investigation revealed that the specific protein kinase C (PKC) inhibitors exhibited stimulatory effects on CRE-driven reporter transcription, and blockage of Ca(2+) signals and inhibition of Ca(2+)-dependent calcineurin resulted in a significant decrease in the luciferase activity. Taken together, these results suggest that PKC likely acts as a negative regulator to modulate CREB activation; in contrast, Ca(2+) signals and Ca(2+)-dependent calcineurin, in addition to PKA, essentially contribute to the positive regulation of CREB activity. This study presents evidence to elucidate the underlying molecular mechanism by which CREB activation is regulated in insects.

Genetic modification of baculovirus expression vectors

As a protein expression vector, the baculovirus demonstrates many advantages over other vectors. With the development of biotechnology, baculoviral vectors have been genetically modified to facilitate high level expression of heterologous proteins in both insect and mammalian cells. These modifications include utilization of different promoters and signal peptides, deletion or replacement of viral genes for increasing protein secretion, integration of polycistronic expression cassette for producing protein complexes, and baculovirus pseudotyping, promoter accommodation or surface display for enhancing mammalian cell targeting gene delivery. This review summarizes the development and the current state of art of the baculovirus expression system. Further development of baculovirus expression systems will make them even more feasible and accessible for advanced applications.

Enhanced expression of recombinant proteins utilizing a modified baculovirus expression vector

The baculovirus expression vector system (BEVS) has been widely used for over-expressing eukaryotic proteins due to a close resemblance in post-translational modification, processing, and transportation properties of the expressed protein, to that of the mammalian cells. In comparison to the bacterial expression system, protein yield from BEVS is relatively low, resulting in higher cost of production. To improve the existing recombinant protein expression levels, baculovirus homologous region1 (hr1) was strategically integrated into the bacmid-based transfer vectors. Luciferase reporter, human Protein Kinase B-alpha (PKB-A), and N-terminal-modified CYP-1A2 genes were independently cloned in non-hr1 and hr1 constructs for generating respective bacmids and baculoviruses. These recombinant baculoviruses were utilized for comparing the expression levels at varying multiplicity of infections (MOI) and time intervals in Spodoptera frugiperda (Sf21) or Trichoplusia ni (Tni) insect cell lines. Targeted insertion of hr1 upstream to CYP-1A2, PKB-A, and Luciferase genes, compared to the non-hr1 sets, led to 3-, 3.5-, and 4.5-fold increase in the resultant protein levels, respectively. Moreover, at equal protein concentration, the corresponding activity and inhibition characteristics of these high expression hr1 sets were comparable to that of the respective non-hr1 sets. Utilization of this modified baculovirus expression construct offers significant advantage of producing recombinant proteins in a cost-effective manner for various biotechnological and therapeutic applications.

Baculovirus immediately early 1, a mediator for homologous regions enhancer function in trans

BACKGROUND

Enhancers are DNA sequences that serve as binding sites for regulatory proteins, and stimulate transcriptional activity independent of their positions and orientations with respect to the transcriptional initiation site. Previous studies considered that baculovirus homologous regions (hrs) function as enhancers in cis. In our study, a plasmid containing homologous region 3 (hr3) enhancer from Bombyx mori nucleopolyhedrovirus (BmNPV) failed to enhance transcription of promoter in other plasmid in co-transfection assays, but strong stimulation occurred when cells were infected by BmNPV.

RESULTS

The cotransfection results of each BmNPV genomic library plasmid, hr3 plasmid and reporter plasmid showed that there were eight library plasmids stimulated the luciferase gene expression remarkably. Sequencing these plasmids revealed that each of them contained the ie-1 gene. Transfected plasmids, containing ie-1, hr3 and various origin promoter drove reporter gene showed the function was even retained. Cotransfection of hr3 functional dissected fragment and ie-1 revealed that the 30-bp imperfect palindrome destroyed fragment can't enhance reporter gene expression even though transfected with ie-1.

CONCLUSION

IE-1 was the only early factor of BmNPV that could act as a mediator for hr enhancer function in trans and the trans-function was achieved with a broad-spectrum of promoters. The 30-bp imperfect palindrome was the elementary molecular structure by which IE-1 participated in the enhancer function in trans.

Homology of dipteran bristles and lepidopteran scales: requirement for the Bombyx mori achaete-scute homologue ASH2

Lepidopteran wing scales and Drosophila bristles are considered homologous structures on the basis of the similarities in their cell lineages. However, the molecular mechanisms underlying scale development are essentially unknown as analysis of gene function in Lepidoptera is sorely limited. In this study, we used the Bombyx mori mutant scaleless (sl), which displays a nearly complete loss of wing scales, to explore the mechanism of lepidopteran wing-scale formation. We found that Bm-ASH2, one of four Bombyx achaete-scute homologs, is highly expressed in early pupal wings of wild-type silkworms, but its expression is severely reduced in sl pupal wings. Through molecular characterization of the mutant locus using luciferase and gel shift assays, genetic analysis of recombining populations, and in vivo rescue experiments, we provide evidence that a 26-bp deletion within the Bm-ASH2 promoter is closely linked to the sl locus and leads to loss of Bm-ASH2 expression and the scaleless-wings phenotype. Thus, the Bm-ASH2 appears to play a critical role in scale formation in B. mori. This finding supports the proposed homology of lepidopteran scales and dipteran bristles and provides evidence for conservation of the genetic pathway in scale/bristle development at the level of gene function.

High-throughput insect cell protein expression applications

The Baculovirus Expression Vector System (BEVS) is one of the most efficient systems for production of recombinant proteins and consequently its application is wide-spread in industry as well as in academia. Since the early 1970s, when the first stable insect cell lines were established and the infectivity of bacu-lovirus in an in vitro culture system was demonstrated (1, 2), virtually thousands of reports have been published on the successful expression of proteins using this system as well as on method improvement. However, despite its popularity the system is labor intensive and time consuming. Moreover, adaptation of the system to multi-parallel (high-throughput) expression is much more difficult to achieve than with E. coli due to its far more complex nature. However, recent years have seen the development of strategies that have greatly enhanced the stream-lining and speed of baculovirus protein expression for increased throughput via use of automation and miniaturization. This chapter therefore tries to collate these developments in a series of protocols (which are modifications to standard procedure plus several new approaches) that will allow the user to expedite the speed and throughput of baculovirus-mediated protein expression and facilitate true multi-parallel, high-throughput protein expression profiling in insect cells. In addition we also provide a series of optimized protocols for small and large-scale transient insect cell expression that allow for both the rapid analysis of multiple constructs and the concomitant scale-up of those selected for on-going analysis. Since this approach is independent of viral propagation, the timelines for this approach are markedly shorter and offer a significant advantage over standard bacu-lovirus expression approach strategies in the context of HT applications.

Analysis of four achaete-scute homologs in Bombyx mori reveals new viewpoints of the evolution and functions of this gene family

Background

achaete-scute complexe (AS-C) has been widely studied at genetic, developmental and evolutional levels. Genes of this family encode proteins containing a highly conserved bHLH domain, which take part in the regulation of the development of central nervous system and peripheral nervous system. Many AS-C homologs have been isolated from various vertebrates and invertebrates. Also, AS-C genes are duplicated during the evolution of Diptera. Functions besides neural development controlling have also been found in Drosophila AS-C genes.

Results

We cloned four achaete-scute homologs (ASH) from the lepidopteran model organism Bombyx mori, including three proneural genes and one neural precursor gene. Proteins encoded by them contained the characteristic bHLH domain and the three proneural ones were also found to have the C-terminal conserved motif. These genes regulated promoter activity through the Class A E-boxes in vitro. Though both Bm-ASH and Drosophila AS-C have four members, they are not in one by one corresponding relationships. Results of RT-PCR and real-time PCR showed that Bm-ASH genes were expressed in different larval tissues, and had well-regulated expressional profiles during the development of embryo and wing/wing disc.

Conclusion

There are four achaete-scute homologs in Bombyx mori, the second insect having four AS-C genes so far, and these genes have multiple functions in silkworm life cycle. AS-C gene duplication in insects occurs after or parallel to, but not before the taxonomic order formation during evolution.

Polydnavirus Genes that Enhance the Baculovirus Expression Vector System

The baculovirus expression vector system (BEVS) is a powerful and versatile system for protein expression, which has many advantages. However, a limitation of any lytic viral expression system, including BEVS, is that death and lysis of infected insect cells terminates protein production. This results in interruption of protein production and higher production costs due to the need to set up new infections, maintain uninfected cells, and produce pure viral stocks. Genetic methods to slow or prevent cell death while maintaining high-level, virus-driven protein production could dramatically increase protein yields. Several approaches have been used to improve the BEVS and increase the synthesis of functional proteins. Successful enhancement of the BEVS was obtained when various gene elements were added to the virus, secretion and posttranslational processing were modified, or protein integrity was improved. A gene family from the insect virus Campoletis sonorensis ichnovirus (CsIV) was discovered that delays lysis of baculovirus-infected cells, thereby significantly enhancing recombinant protein production in the BEVS system. By using the CsIV vankyrin gene family, protein production in the vankyrin-enhanced BEVS (VE-BEVS) was increased by a factor of 4- to 15-fold by either coexpressing the vankyrin protein from a dual BEVS or by providing its activity in trans by expressing the vankyrin protein from a stably transformed cell line. In sum, VE-BEVS is an enhancement of the existing BEVS technology that markedly improves protein expression levels while reducing the cost of labor and materials.

Preliminary characterisation of repeat families in the genome of EhV-86, a giant algal virus that infects the marine microalga Emiliania huxleyi

EhV-86 is a large double stranded DNA virus with a 407,339 base pair circular genome that infects the globally important microalga Emiliania huxleyi. It belongs to a new genus of viruses termed the Coccolithoviridae within the algal virus family Phycodnaviridae. By plotting the EhV-86 genome against itself in a dot-plot analysis we revealed three families of distinctly different repeat sequences throughout its genome, designated Family A, B and C. Family A repeats are non-coding, found immediately upstream of 86 predicted coding sequences (CDSs) and are likely to play a crucial role in controlling the expression of the associated CDSs. Family B repeats are GC rich, coding and correspond to possible calcium binding sites in 22 proline-rich domains found in the protein products of eight predicted EhV-86 CDSs. Family C repeats are AT-rich, non-coding and are likely to form part of the origin of replication. We suggest that these repeat regions are of fundamental importance during virus propagation being involved with transcriptional control (Family A), virus adsorption/release (Family B) and DNA replication (Family C).

Baculovirus as versatile vectors for protein expression in insect and mammalian cells

Today, many thousands of recombinant proteins, ranging from cytosolic enzymes to membrane-bound proteins, have been successfully produced in baculovirus-infected insect cells. Yet, in addition to its value in producing recombinant proteins in insect cells and larvae, this viral vector system continues to evolve in new and unexpected ways. This is exemplified by the development of engineered insect cell lines to mimic mammalian cell glycosylation of expressed proteins, baculovirus display strategies and the application of the virus as a mammalian-cell gene delivery vector. Novel vector design and cell engineering approaches will serve to further enhance the value of baculovirus technology.