HeLa Cell Factor Research Articles

Effects of curcumin on Wnt/β-catenin, Hedgehog pathways and expression of EMT transcription factors in basal conditions and upon HIF1A and RELA knockdown in HeLa cells

Targeting the HIF1A and NF-κB pathways with pharmacological inhibitors or small interfering RNAs is one of the most promising aspects of cancer stem cell therapy. However, the influence of HIF1A and NF-κB modulators on downstream targets such as components of the Wnt/β-catenin and Hedgehog pathways and EMT is still poorly understood.HeLa cells were treated with 10 and 50 μM curcumin for 24 h, and the function of the Wnt/β-catenin and Hedgehog pathways and EMT transcription factors were subsequently assessed using 14 RNAs expression qPCR-based analysis. We also applied siRNA-dependent HIF1A and RELA knockdown to investigate the influence of these pathways on the expression of the above RNAs along and in combination with curcumin treatment.At the higher concentration under basal conditions, curcumin suppressed most of the targets studied, while causing a significant increase in SNAI1 expression. Knockdown of HIF1A and RELA reduced the expression of Hedgehog pathway targets. In contrast to basal conditions, the expression of EMT transcription factors appeared to be increased after knockdown in response to 50 μM curcumin.Curcumin significantly inhibited Wnt/β-catenin, Hedgehog pathways and EMT transcription factor, while inducing an increase in SNAI1 gene expression, which may be part of cell adaptation systems. Knockdown of HIF1A and RELA revealed the strong dependence of Hedgehog target expression on HIF1A and NF-κB pathways. The activation status of HIF1A and NF-κB pathways determines the expression pattern of EMT transcription factors in HeLa cells.

Cdc25B is transcriptionally inhibited by IER5 through the NF-YB transcription factor in irradiation-treated HeLa cells.

Cervical cancer (CC) is a type of pelvic malignant tumor that severely threatens women's health. Current evidence suggests that IER5, as a potential radiosensitizer, promotes irradiation-induced apoptosis in CC tissues in patients undergoing chemoradiotherapy. IER5 has been shown to be involved in the G2/M-phase transition. In the present study, we used Cdc25B as the breakthrough point to explore the underlying mechanism of IER5 in the cell cycle regulation of radiation-damaged HeLa cells. IER5 was evidently upregulated after irradiation, but Cdc25B was significantly downregulated. In monoclonal IER5-silenced HeLa cells, irradiation-induced downregulation of Cdc25B was attenuated. The effect of irradiation on Cdc25B promoter activity was determined by dual-luciferase reporter assays. The response elements on the Cdc25B promoter related to irradiation were predicted by JASPAR. These conserved sequences were mutated individually or in combination by splicing-by-overlap extension PCR, and their function was confirmed by dual-luciferase reporter assays. The enrichment efficiency of transcription factors after irradiation was determined by chromatin immunoprecipitation (ChIP) assay. Both Sp1/Sp3 and NF-YB binding sites were involved in irradiation-mediated regulation of Cdc25B. IER5 was involved in irradiation-mediated regulation of Cdc25B through the NF-YB binding site. Furthermore, ChIP assays showed that IER5 bound to the Cdc25B promoter, and the binding of IER5 to the Cdc25B promoter region in irradiation-induced HeLa cells induced the release of the coactivator p300 through interaction with NF-YB. Taken together, these findings indicate that IER5 is the transcriptional repressor that accelerates the downregulation of Cdc25B expression after irradiation.

RBM4 regulates M1 macrophages polarization through targeting STAT1-mediated glycolysis

M1/M2 macrophages polarization play important roles in regulating tissue homeostasis. Recently, RNA-binding motif 4 (RBM4) has been reported to modulate the proliferation and expression of inflammatory factors in HeLa cells. However, whether RBM4 is involved in regulating macrophage polarization and inflammatory factor expression are still unknown. In this study, RAW264.7, a mouse macrophage cell line, were stimulated with interferon γ (IFN-γ) or interleukin‐4 (IL‐4) to induce M1/M2 macrophages polarization. We found that IFN-γ, but not IL-4, stimulation decreased RBM4 expression in macrophages, and RBM4 overexpression inhibits IFN-γ-induced M1 macrophage polarization. Furthermore, RNA-Sequencing, protein immunoprecipitation accompanied with mass spectrometry, and extracellular acidification rate analysis showed that RBM4 suppresses IFN-γ-induced M1 macrophage polarization though inhibiting glycolysis. Moreover, RBM4 knockdown promoted IFN-γ-induced signal transducer and activator of transcription 1 (STAT1) activation via increasing STAT1 mRNA stability, leading to the increase of glycolysis-related gene transcripts regulated by STAT1. Finally, we find that RBM4 interacts with YTH N6-methyladenosine RNA binding protein 2 (YTHDF2) to degrade m6A modified STAT1 mRNA, thereby regulating glycolysis and M1 macrophage polarization. Collectively, the current study firstly reports that RBM4 regulates M1 macrophages polarization through targeting STAT1-mediated glycolysis and shows that RBM4 is a possible candidate for regulating macrophage M1 polarization and inflammatory responses.

Interleukin-22 derived from cervical cancer-associated fibroblasts accelerates senescence of normal fibroblasts and promotes expression of tumorigenesis-related factors in HeLa cells

Interleukin-22 derived from cervical cancer-associated fibroblasts accelerates senescence of normal fibroblasts and promotes expression of tumorigenesis-related factors in HeLa cells

RBM4 modulates the proliferation and expression of inflammatory factors via the alternative splicing of regulatory factors in HeLa cells

Regulatory factors function by modulating a variety of cascade mechanisms in cells. RBM4 is a multifunctional RNA-binding protein in post-transcriptional gene regulation. Cytoplasmic RBM4 interacts with Ago2 to regulate inflammatory responses by affecting mRNA decay and cap-dependent translation. However, it is unclear whether RBM4 functions in inflammation regulation by its splicing factor role. Here, the cell biology, gene expression profile and alternative splicing pattern of HeLa cells with RBM4 overexpression (RBM-OE) were compared with the control. The results showed that RBM4-OE inhibited proliferation. RBM4-OE extensively affects the transcriptional level of genes involved in cell surface receptor signalling pathway, inflammatory responses and the response to lipopolysaccharide. RBM4 broadly regulated the alternative splicing of hundreds of genes with functions of protein binding, helicase activity, DNA binding and transcription co-activator. RBM4-regulated splicing of these genes plays an important role in apoptotic process and gene transcription regulation. As an example, exon inclusion of TNIP1 mediated by RBM4 affects the expression of its targets in inflammatory pathways. These results indicated that RBM4 can mediate the inflammatory response via splicing regulation, which adds to the understanding of the critical role of RBM4 in cancer complicated by inflammation. In conclusion, this study indicated a mechanism in which the dysregulation of alternative splicing can influence cellular biology and lead to various immune-related diseases.

PARP1 regulates DNA damage-induced nucleolar-nucleoplasmic shuttling of WRN and XRCC1 in a toxicant and protein-specific manner

The prime function of nucleoli is ribogenesis, however, several other, non-canonical functions have recently been identified, including a role in genotoxic stress response. Upon DNA damage, numerous proteins shuttle dynamically between the nucleolus and the nucleoplasm, yet the underlying molecular mechanisms are incompletely understood. Here, we demonstrate that PARP1 and PARylation contribute to genotoxic stress-induced nucleolar-nucleoplasmic shuttling of key genome maintenance factors in HeLa cells. Our work revealed that the RECQ helicase, WRN, translocates from nucleoli to the nucleoplasm upon treatment with the oxidizing agent H2O2, the alkylating agent 2-chloroethyl ethyl sulfide (CEES), and the topoisomerase inhibitor camptothecin (CPT). We show that after treatment with H2O2 and CEES, but not CPT, WRN translocation was dependent on PARP1 protein, yet independent of its enzymatic activity. In contrast, nucleolar-nucleoplasmic translocation of the base excision repair protein, XRCC1, was dependent on both PARP1 protein and its enzymatic activity. Furthermore, gossypol, which inhibits PARP1 activity by disruption of PARP1-protein interactions, abolishes nucleolar-nucleoplasmic shuttling of WRN, XRCC1 and PARP1, indicating the involvement of further upstream factors. In conclusion, this study highlights a prominent role of PARP1 in the DNA damage-induced nucleolar-nucleoplasmic shuttling of genome maintenance factors in HeLa cells in a toxicant and protein-specific manner.

Transgelin 2 overexpression inhibits cervical cancer cell invasion and migration.

Cervical cancer is a malignancy that threatens female health. The present study aimed to investigate the role of transgelin 2 (TAGLN2) in cervical cancer. Reverse transcription‑quantitative polymerase chain reaction and western blotting were conducted to detect the mRNA and protein expression levels of particular factors in HeLa cells. Cell Counting kit‑8, wound healing and Transwell assays were conducted to determine cell viability, and migratory and invasive abilities, respectively. The results demonstrated that the expression levels of TAGLN2 were decreased in cervical cancer tissues and were associated with the survival time of patients with cervical cancer. In addition, the expression of TAGLN2 was significantly reduced in three cervical cancer cell lines (HeLa, SiHa and C‑33A) compared with in a normal cervical cell line. The present study also demonstrated that TAGLN2 overexpression in HeLa cells could inhibit cell viability, migration and invasion, and it was suggested that this may occur via upregulation of the expression levels of E‑cadherin and inhibitor of nuclear factor κ‑light‑chain‑enhancer of activated B cells (NF‑κB) (IκB), and downregulation of C‑X‑C chemokine receptor type 4, matrix metalloproteinase (MMP)‑2, MMP‑9, p50 and transcription factor p65. In conclusion, TAGLN2 was revealed to inhibit cell viability, and the migratory and invasive abilities of HeLa cervical cancer cells via regulating the expression of metastasis‑associated factors and the NF‑κB signaling pathway. The present study proposed a novel target gene for the diagnosis, treatment and prognosis of cervical cancer.

Effects and possible mechanism of a picosecond pulsed electric field on angiogenesis in cervical cancer in vitro.

Picosecond pulsed electric field (psPEF) is an athermal, minimally invasive and local ablative biomedical engineering technique used in cancer therapy. However, to the best of our knowledge, the effect of psPEF on angiogenesis in cervical cancer is unknown. Therefore, the aim of the current study was to investigate the effects and possible mechanism of psPEF on angiogenesis in cervical cancer in vitro. HeLa cell and human umbilical vein endothelial cell (HUVEC) suspensions were exposed to psPEF with an increasing gradient of electric field intensity (0, 200, 400 and 600 kV/cm). A Cell Counting kit-8 assay and flow cytometry were used to investigate the effect of psPEF on the proliferation and apoptosis of HUVECs. The invasion, migration and tube formation capabilities of HUVECs following psPEF treatment were investigated by Transwell invasion assay, scratch test and lumen formation assay, respectively. Changes in the protein and mRNA levels of angiogenesis-associated factors in HeLa cells were detected by western blot analysis and reverse transcription-quantitative polymerase chain reaction. psPEF was identified to inhibit proliferation and tube formation, and induce apoptosis and necrosis of HUVECs in a dose-dependent manner. psPEF was revealed to decrease the protein and mRNA expression levels of vascular endothelial growth factor and hypoxia-inducible factor 1α in HeLa cells. In summary, psPEF exhibited anti-angiogenic effects in cervical cancer in vitro by exerting direct effects on HUVECs and indirect effects on angiogenesis-associated factors in HeLa cells.

Anti-proliferative effect of RCE-4 from Reineckia carnea on human cervical cancer HeLa cells by inhibiting the PI3K/Akt/mTOR signaling pathway and NF-κB activation.

Cervical cancer is the second leading cause of cancer deaths in women worldwide. In recent years, the studies find that inflammation is a critical component of tumor progression, and the ideal therapeutic methods should be aimed at the inflammation reaction triggers. (1β,3β,5β,25S)-spirostan-1,3-diol1-[α-L-rhamnopyranosyl-(1 → 2)-β-D-xylopyranoside] (RCE-4) was the main active composition of Reineckia carnea (Andr.) Kunth. It significantly induced apoptosis in cervical cancer Caski cells through the mitochondrial pathway in our previous studies; however, its underlying mechanism remains poorly understood. This study aimed to further evaluate the effect of RCE-4 on human cervical cancer HeLa cells. Based on this observation, we investigated the anti-cervical cancer effect of RCE-4 by modulating phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway, nuclear factor-kappa B (NF-κB) activation, and inflammation-related key factors in HeLa cells. The results indicated that the HeLa cell was the most sensitive with an IC50 of 7.01μM; RCE-4 significantly promoted the release of cellular lactate dehydrogenase (LDH); increased DNA fragmentation and apoptosis; reduced PI3K, Akt, mTOR, and NF-κBp65 phosphorylation levels; increased the Bax and cleaved poly (ADP-ribose) polymerase (PARP) protein levels; suppressed Bcl-2 protein expression; elevated the Bax/Bcl-2 expression ratio; and decreased the interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) mRNA expressions in HeLa cells in a concentration-dependent manner. These findings suggest that RCE-4 exerted beneficially anti-cervical cancer effect on HeLa cells, mainly inhibiting PI3K/Akt/mTOR signaling pathway phosphorylation and NF-κB activation, promoting HeLa cell apoptosis. Graphical abstract Anti-tumor effect of RCE-4 on HeLa cells.

Construction and analysis of the regulatory network disturbed by the silenced Sp1 transcription factor in HeLa cells.

The objective of our study was to explore the characteristics of the regulatory network after siRNA-Sp1 (Specificity Protein 1) treatment in HeLa cells through the regulation network construction with bioinformatics methods. Using GSE37935 datasets downloaded from Gene Expression Omnibus data, the differentially expressed genes (DEGs) were screened out by the limma package in R software. Combining the DEGs with the data from the microRNA (miRNA) databases and transcription factor databases, an integrated regulatory network was established with Cytoscape. Then the motifs in the network were examined by FANMOD. A total of 708 DEGs were screened, and a regulatory network consisting of 585 nodes and 1070 edges was constructed. By analyzing the two modules extracted from the network, we found that the most significant biological processes were cell cycle and apoptosis, some significant DEGs among them were CDKN1A, CUL5, and EGFR. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis discovered that DEGs, including EGFR, CDKN1A, RRM2B, and GADD45B, were significantly enriched in glioma pathway and p53 signaling pathway. While Sp1 was silenced by siRNA, the regulatory network in HeLa cells changed a lot. Genes related to cell cycle and apoptosis in the cell nucleus were dysregulated and the p53 signaling pathway was disturbed.

Anthocyanins fromVitis coignetiaePulliat Inhibit Cancer Invasion and Epithelial-Mesenchymal Transition, but These Effects Can Be Attenuated by Tumor Necrosis Factor in Human Uterine Cervical Cancer HeLa Cells

Recently we have demonstrated that anthocyanins from fruits of Vitis coignetiae Pulliat (AIMs) have anticancer effects. Here, we investigate the effects of AIMs on cell proliferation and invasion as well as epithelial-mesenchymal transition (EMT) which have been linked to cancer metastasis in human uterine cervical cancer HeLa cells. AIMs inhibited the invasion of HeLa cells in a dose-dependent manner. AIMs inhibited MMP-9 expression in a dose-dependent manner. AIMs inhibited the motility of HeLa cells in a wound healing test. AIMs still suppressed NF-κB activation induced by TNF. AIMs also inhibited EMT in HeLa cells. AIMs suppressed vimentin, N-cadherin, and β-catenin expression and induced E-cadherin. AIMs also suppressed expression of β-catenin and Snail, which was regulated by GSK-3. These effects of AIMs were also limited in the HeLa cells treated with TNF. In conclusion, this study indicates that AIMs have anticancer effects by suppressing NF-κB-regulated genes and EMT, which relates to suppression of IκBα phosphorylation and GSK-3 activity, respectively. However, the effects of AIMs were attenuated in the TNF-high condition.

Transcriptional roles for DNA repair factors

The xeroderma pigmentosum factors XPG and XPF are DNA repair endonucleases; however, various roles in transcription have also been proposed. Le May et al. investigated further by knocking down xeroderma pigmentosum factors in HeLa cells and studying the effects on the induction of the RARB gene (which is induced by retinoic acid) and on various molecular features at the RARB locus. They found that XPG and XPF are required for optimal RARB transcription by a complex mechanism involving single-strand DNA break generation, DNA demethylation, CTCF transcription factor recruitment and chromosomal looping to bring the promoter and terminator sequences into proximity.

REST is up-regulated by epidermal growth factor in HeLa cells and inhibits apoptosis by influencing histone H3 acetylation

REST (repressor element 1-silencing transcription factor) is a transcription factor that recruits histone deacetylases to silence gene transcription. REST appears to play a paradoxical role in cancer cells: it exhibits tumor suppressor activity or promotes tumorigenesis, depending upon the setting. The extracellular signaling molecules that control REST gene expression in cancer cells remain poorly understood. In this study, we report that REST expression in HeLa cells is elevated in cells exposed to epidermal growth factor or serum, whereas the rate of cell apoptosis is low. Apoptosis induced by serum withdrawal is significantly increased in HeLa cells treated with an antisense phosphorothioate oligodeoxynucleotide (AS ODN) capable of down-regulating REST expression, whereas in HeLa cells transfected with a REST expressing plasmid, REST overexpression reduces the marked apoptosis caused, in absence of serum, by exposure to an anti-Fas receptor antibody imitating the Fas ligand activity plus PD 98059, a blocker of extracellular signal-regulated kinase 1/2 activation. REST knockdown also reduces mRNA levels of the antiapoptotic protein Bcl-XL whereas in HeLa cells overexpressing REST, the reduction of Bcl-XL mRNA caused by the anti-Fas receptor antibody plus PD 98059 is significantly decreased. Finally, we report that acetylation of histone H3 is increased in HeLa cells exposed to AS ODN or anti-Fas receptor antibody, whereas it is reduced in cells transfected with the REST expressing plasmid. Our findings indicate that REST is a novel gene regulated by EGF in HeLa cells that potentially contributes to the modulation of apoptosis via epigenetic mechanisms.

Diacylglycerol Kinase η Augments C-Raf Activity and B-Raf/C-Raf Heterodimerization

The Ras/B-Raf/C-Raf/MEK/ERK signaling cascade is critical for the control of many fundamental cellular processes, including proliferation, survival, and differentiation. This study demonstrated that small interfering RNA-dependent knockdown of diacylglycerol kinase eta (DGKeta) impaired the Ras/B-Raf/C-Raf/MEK/ERK pathway activated by epidermal growth factor (EGF) in HeLa cells. Conversely, the overexpression of DGKeta1 could activate the Ras/B-Raf/C-Raf/MEK/ERK pathway in a DGK activity-independent manner, suggesting that DGKeta serves as a scaffold/adaptor protein. By determining the activity of all the components of the pathway in DGKeta-silenced HeLa cells, this study revealed that DGKeta activated C-Raf but not B-Raf. Moreover, this study demonstrated that DGKeta enhanced EGF-induced heterodimerization of C-Raf with B-Raf, which transmits the signal to C-Raf. DGKeta physically interacted with B-Raf and C-Raf, regulating EGF-induced recruitment of B-Raf and C-Raf from the cytosol to membranes. The DGKeta-dependent activation of C-Raf occurred downstream or independently of the already known C-Raf modifications, such as dephosphorylation at Ser-259, phosphorylation at Ser-338, and interaction with 14-3-3 protein. Taken together, the results obtained strongly support that DGKeta acts as a novel critical regulatory component of the Ras/B-Raf/C-Raf/MEK/ERK signaling cascade via a previously unidentified mechanism.

ERK MAP kinase-activated Arf6 trafficking directs coxsackievirus type B3 into an unproductive compartment during virus host-cell entry

Clathrin- and caveolae-mediated endocytosis have been implicated in the productive entry of many viruses into host cells. ADP-ribosylation factor 6 (Arf6)-dependent endocytosis is another endocytosis pathway that traffics from the cell surface and it is the only Arf that traffics at the plasma membrane. However, little is known about Arf6-dependent trafficking during virus entry. This study showed that coxsackievirus type B3 (CVB3) associated with decay-accelerating factor in non-polarized HeLa cells can be redirected into non-productive compartments by Arf6-dependent internalization, thus restricting infection. Overexpression of wild-type (WT) and constitutively active (CA) Arf6 in HeLa cells resulted in a 2.3- and 3.6-fold decrease in infection, respectively. A dominant-negative inhibitor of Arf6 recovered restriction of infection by WT-Arf6 and CA-Arf6. RNA interference of endogenous Arf6 resulted in a 3.3-fold increase in CVB3 titre in HeLa cells. It was shown that coxsackie-adenovirus receptor (CAR) ligation by virus or CAR-specific antibody could activate extracellular signal-regulated kinase (ERK) of the mitogen-activated protein kinase family and lead to Arf6-mediated viral restriction. In the absence of ERK activation, CVB3 internalization into early endosomes was inhibited and subsequent infection was reduced, but Arf6-mediated restriction was also abolished. In conclusion, receptor-mediated signalling enhances CVB3 entry whilst also activating non-productive pathways of virus entry; thus, virus infection is an equilibrium of productive and non-productive pathways of entry.

Activation of Cytosolic Phospholipase A2α by Epidermal Growth Factor (EGF) and Phorbol Ester in HeLa Cells: Different Effects of Inhibitors for EGF Receptor, Protein Kinase C, Src, and C-Raf

In several types of cancer cells, prostaglandins produced via the over-expression of epidermal growth factor receptor (EGFR) and cyclooxygenases regulate cell growth. We investigated the signaling mechanisms for the release of arachidonic acid (AA, a precursor for prostaglandins) in human cervical carcinoma HeLa cells. Treatment with EGF and 4β-phorbol 12-myristate 13-acetate (PMA) with A23187 released AA accompanied by the phosphorylation of extracellular signal-regulated kinases (ERK1/2). Pharmacological experiments showed that the responses (ERK phosphorylation and AA release) induced by EGF and PMA were mediated by a mitogen-activated protein kinase/ERK kinase (MEK) – ERK – α-type cytosolic phospholipase A2 (cPLA2α) pathway and that EGFR couples with the pathway in a manner insensitive to sorafenib, an inhibitor of B- and C-Raf, enzymes upstream of MEK. Activation of protein kinase C by PMA couples with the pathway partly in a sorafenib-sensitive and probably C-Raf–mediated manner and partly in a family of Src tyrosine kinases (Src)–dependent and sorafenib-insensitive manner. Co-treatment with sorafenib and an inhibitor of Src family members additionally inhibited the PMA-induced release of AA. Cross-talk between EGFR and protein kinase C was not observed. In human lung carcinoma A549 cells, the release of AA by EGF was insensitive to sorafenib. Possible mechanisms for the sorafenib-insensitive activation of the MEK–ERK–cPLA2α pathway are discussed.

Nucleolar Localization of Upstream Binding Factor in HeLa Cells Depends on rRNA Synthesis Activities

During Pol I-mediated rRNA synthesis, UBF plays a key role in transcription. Numerous localization studies provided, however, rather divergent results with regard to its presence in either of the two structural nucleolar subcompartments, FC and DFC. These observations suggest different roles of UBF within nucleoli. In order to expand our knowledge in this respect, we have performed the ultrastructural localization of UBF and DNA in HeLa cell nucleoli and complemented it with mapping DNA/RNA hybrids, which testify for the presence of newly synthesized rRNA. With immunogold UBF mapping, the results fell, depending on the type of nucleoli, basically into two categories. In nucleoli exhibiting one, or at most a few, large FC, UBF molecules were mapped mainly into FC. Such nucleoli are known to possess lower activity in rRNA synthesis. In the second category of reticulated nucleoli with many tiny FCs, which are characterized by high rRNA gene transcription, the gold particles were enriched mainly in DFC/FC borders and DFC. The established differential localization of UBF in nucleoli of HeLa cells thus has a functional meaning. It reflects both the level of rRNA synthesis activities and the architectural role of UBF in nucleoli of these cells.

Identification of 1,4GalT II as a Target Gene of p53-mediated HeLa Cell Apoptosis

beta1,4-galactosyltransferase II (beta1,4GalT II) is one of the enzymes transferring galactose to the terminal N-acetylglucosamine of complex-type N-glycans. Previously, we have reported that beta1,4GalT II overexpression increased cisplatin-induced HeLa cell apoptosis. However, the mechanisms of its expression regulation have been rarely investigated. Here, we cloned the 1.8-kb 5'-flanking region of the beta1,4GalT II gene and analysed its promoter activity. The transcriptional activity and mRNA expression level of beta1,4GalT II were dramatically induced by p53 transcription factor in HeLa cells. In response to DNA damage agent adriamycin, the mRNA expression and promoter activity of beta1,4GalT II were significantly up-regulated and the binding of p53 to beta1,4GalT II promoter was obviously increased. Furthermore, decreasing the expression of beta1,4GalT II using RNA interference inhibited p53-mediated HeLa cell apoptosis induced by adriamycin. Collectively, these results suggested that beta1,4GalT II might serve as a target gene of p53 transcription factor during adriamycin-induced HeLa cell apoptosis, which elucidated a new mechanism of p53-mediated cell apoptosis.

On the Effect of Transient Expression of Mutated eIF2α and eIF4E Eukaryotic Translation Initiation Factors on Reporter Gene Expression in Mammalian Cells Upon Cold-Shock

There are a growing number of reports on the beneficial effects of subphysiological temperature in vitro culturing (27-35 degrees C) of mammalian cells on recombinant protein yield. However, this effect is not conserved across cell lines and target products, and our understanding of the molecular mechanism(s) responsible for increased recombinant protein yield upon reduced temperature culturing of mammalian cells is poor. What is known is that mammalian cells respond to cold-shock by attenuating global cap-dependent translation. Here, we have investigated the hypothesis that the cap-dependent attenuation of mRNA translation upon cold-stress of in vitro-cultured mammalian cells can be prevented, or at least alleviated, by overexpressing mutant translation initiation factors in Chinese hamster ovary and HeLa cells. We have shown that the transient coexpression of either an eIF2alphaSer51 Ala51 mutant or an eIF4ESer209 Glu209 mutant with firefly luciferase affects luciferase expression levels in a cell line and temperature dependent manner. Further, regardless of the coexpression of initiation factors, transient reporter gene expression was enhanced at subphysiological temperatures (<37 degrees C), suggesting that reduced temperature cultivation can be used to improve the yield of recombinant protein during transient expression. The implications of these results upon cell engineering strategies involving manipulation of the translational apparatus for the enhancement of recombinant protein synthesis upon cold-shock are discussed.

Vaccinia Virus Intermediate Stage Transcription Is Complemented by Ras-GTPase-activating Protein SH3 Domain-binding Protein (G3BP) and Cytoplasmic Activation/Proliferation-associated Protein (p137) Individually or as a Heterodimer

Transcription of the DNA genome of vaccinia virus occurs in the cytoplasm and is temporally programmed by early, intermediate, and late stage-specific transcription factors in conjunction with a viral multisubunit RNA polymerase. The RNA polymerase, capping enzyme, and three factors (VITF-1, VITF-2, and VITF-3) are sufficient for in vitro transcription of a DNA template containing an intermediate stage promoter. Vaccinia virus intermediate transcription factor (VITF)-1 and -3 are virus-encoded, whereas VITF-2 was partially purified from extracts of uninfected HeLa cells. Using purified and recombinant viral proteins, we showed that the HeLa cell factor was required for transcription of linear or nicked circular templates but not of super coiled DNA. HeLa cell polypeptides of approximately 110 and 66 kDa copurified with VITF-2 activity through multiple chromatographic steps. The polypeptides were separated by SDS-polyacrylamide gel electrophoresis and identified by mass spectrometry as Ras-GTPase-activating protein SH3 domain-binding protein (G3BP) and p137, recently named cytoplasmic activation/proliferation-associated protein-1. The co-purification of the two polypeptides with transcription-complementing activity was confirmed with specific antibodies, and their association with each other was demonstrated by affinity chromatography of tagged recombinant forms. Furthermore, recombinant G3BP and p137 expressed individually or together in mammalian or bacterial cells complemented the activity of the viral RNA polymerase and transcription factors. The involvement of cellular proteins in transcription of intermediate stage genes may regulate the transition between early and late phases of vaccinia virus replication.