Differential gene expression in apoptosis: identification of ribosomal protein S29 as an apoptotic inducer

Disulfidptosis: A new type of cell death

Disulfidptosis is a novel form of cell death that is distinguishable from established programmed cell death pathways such as apoptosis, pyroptosis, autophagy, ferroptosis, and oxeiptosis. This process is characterized by the rapid depletion of nicotinamide adenine dinucleotide phosphate (NADPH) in cells and high expression of solute carrier family 7 member 11 (SLC7A11) during glucose starvation, resulting in abnormal cystine accumulation, which subsequently induces andabnormal disulfide bond formation in actin cytoskeleton proteins, culminating in actin network collapse and disulfidptosis. This review aimed to summarize the underlying mechanisms, influencing factors, comparisons with traditional cell death pathways, associations with related diseases, application prospects, and future research directions related to disulfidptosis.

RPS24c Isoform Facilitates Tumor Angiogenesis Via Promoting the Stability of MVIH in Colorectal Cancer

BACKGROUND

Colorectal cancer (CRC) is the second leading cause of death worldwide, and distant metastasis is responsible for the poor prognosis in patients with advanced-stage CRC. RPS24 (ribosomal protein S24) as a ribosomal protein, multiple transcript variant encoding different isoforms have been found for this gene. Our previous studies have demonstrated that RPS24 is overexpressed in CRC. However, the mechanisms underlying the role of RPS24 in tumor development have not been fully defined.

METHODS

Expression of RPS24 isoforms and lncRNA MVIH in CRC tissues and cell lines were quantified by real-time PCR or western blotting assay. Endothelial tube formation assay was performed to determine the effect of RPS24 on tumor angiogenesis. The cell viability of HUVEC was determined by MTT assay, and the migration and invasion ability of HUVEC were detected by transwell assay. PGK1 secretion was tested with a specific ELISA kit.

RESULTS

Here, we found that RPS24c isoform was a major contributor to tumor angiogenesis, a vital process in tumor growth and metastasis. Real-time PCR revealed that RPS24c isoform was highly expressed in CRC tissues, while other isoforms are present in both normal and CRC tissues with no statistical difference. Moreover the change of RPS24 protein level is mainly due to the fluctuation of RPS24c. Furthermore, we observed that silencing RPS24c could decrease angiogenesis by inhibiting tubule formation, HUVEC cell proliferation and migration. Additionally, we investigated the molecular mechanisms and demonstrated that RPS24c mRNA interacted with lncRNA MVIH, the binding-interaction enhanced the stability of each other, thereby activated angiogenesis by inhibiting the secretion of PGK1.

CONCLUSION

RPS24c facilitates tumor angiogenesis via the RPS24c/MVIH/PGK1 pathway in CRC. RPS24c inhibition may be a novel option for anti-vascular treatment in CRC.

An in-depth multi-omics analysis in RLE-6TN rat alveolar epithelial cells allows for nanomaterial categorization

BACKGROUND

Nanomaterials (NMs) can be fine-tuned in their properties resulting in a high number of variants, each requiring a thorough safety assessment. Grouping and categorization approaches that would reduce the amount of testing are in principle existing for NMs but are still mostly conceptual. One drawback is the limited mechanistic understanding of NM toxicity. Thus, we conducted a multi-omics in vitro study in RLE-6TN rat alveolar epithelial cells involving 12 NMs covering different materials and including a systematic variation of particle size, surface charge and hydrophobicity for SiO₂ NMs. Cellular responses were analyzed by global proteomics, targeted metabolomics and SH2 profiling. Results were integrated using Weighted Gene Correlation Network Analysis (WGCNA).

RESULTS

Cluster analyses involving all data sets separated Graphene Oxide, TiO2_NM105, SiO2_40 and Phthalocyanine Blue from the other NMs as their cellular responses showed a high degree of similarities, although apical in vivo results may differ. SiO2_7 behaved differently but still induced significant changes. In contrast, the remaining NMs were more similar to untreated controls. WGCNA revealed correlations of specific physico-chemical properties such as agglomerate size and redox potential to cellular responses. A key driver analysis could identify biomolecules being highly correlated to the observed effects, which might be representative biomarker candidates. Key drivers in our study were mainly related to oxidative stress responses and apoptosis.

CONCLUSIONS

Our multi-omics approach involving proteomics, metabolomics and SH2 profiling proved useful to obtain insights into NMs Mode of Actions. Integrating results allowed for a more robust NM categorization. Moreover, key physico-chemical properties strongly correlating with NM toxicity were identified. Finally, we suggest several key drivers of toxicity that bear the potential to improve future testing and assessment approaches.

Microtubule-dependent ribosome localization in C. elegans neurons

Subcellular localization of ribosomes defines the location and capacity for protein synthesis. Methods for in vivo visualizing ribosomes in multicellular organisms are desirable in mechanistic investigations of the cell biology of ribosome dynamics. Here, we developed an approach using split GFP for tissue-specific visualization of ribosomes in Caenorhabditis elegans. Labeled ribosomes are detected as fluorescent puncta in the axons and synaptic terminals of specific neuron types, correlating with ribosome distribution at the ultrastructural level. We found that axonal ribosomes change localization during neuronal development and after axonal injury. By examining mutants affecting axonal trafficking and performing a forward genetic screen, we showed that the microtubule cytoskeleton and the JIP3 protein UNC-16 exert distinct effects on localization of axonal and somatic ribosomes. Our data demonstrate the utility of tissue-specific visualization of ribosomes in vivo, and provide insight into the mechanisms of active regulation of ribosome localization in neurons.

Highly expressed ribosomal protein L34 indicates poor prognosis in osteosarcoma and its knockdown suppresses osteosarcoma proliferation probably through translational control

Osteosarcoma has devastating health implications on children and adolescents. However, due to its low incidence and high tumor heterogeneity, it is hard to achieve any further improvements in therapy and overall survival. Ribosomal protein L34 (RPL34) has been increasingly recognized to promote the proliferation of malignant cells, but its role in osteosarcoma has not been investigated. In this study, real-time quantitative PCR (RT-qPCR) and immunohistochemistry revealed that RPL34 was highly expressed in osteosarcoma tissues when compared to adjacent tissues and normal bone tissues. Survival analysis showed that high expression of RPL34 predicted a poor prognosis for osteosarcoma patients. Knockdown of RPL34 in Saos-2 cells via lentivirus-mediated small interfering RNA (siRNA) significantly inhibited cell proliferation, induced cell apoptosis and G2/M phase arrest. Moreover, screening of transcription factors using University of California Santa Cruz (UCSC) Genome Browser, protein-protein interaction (PPI) network analysis, Gene Ontology (GO) and pathway enrichment analysis revealed that MYC participates in the transcriptional regulation of RPL34, which interacts with the subunits of eukaryotic translation initiation factor 3 (eIF3) and probably involves the translational control of growth-promoting proteins. Our findings suggest that RPL34 plays an important role in the proliferation of osteosarcoma cells.

Ribosomal L22-like1 (RPL22L1) Promotes Ovarian Cancer Metastasis by Inducing Epithelial-to-Mesenchymal Transition

Double minute chromosomes (DMs) have important implications for cancer progression because oncogenes frequently amplified on them. We previously detected a functionally undefined gene amplified on DMs, Ribosomal L22-like1 (RPL22L1). The relationship between RPL22L1 and cancer progression is unknown. Here, RPL22L1 was characterized for its role in ovarian cancer (OC) metastasis and its underlying mechanism was examined. DNA copy number and mRNA expression of RPL22L1 in OC cells was analyzed using data obtained from The Cancer Genome Atlas and the Gene Expression Omnibus database. An immunohistochemical analysis of clinical OC specimens was performed and the relationships between expression level and clinicopathological factors were evaluated. Additionally, in vivo and in vitro assays were performed to understand the role of RPL22L1 in OC. RPL22L1 expression was higher in OC specimens than in normal tissues, and its expression level was highly positively correlated with invasion and lymph node metastasis (P < 0.05). RPL22L1 over-expression significantly enhanced intraperitoneal xenograft tumor development in nude mice and promoted invasion and migration in vitro. Additionally, RPL22L1 knockdown remarkably inhibited UACC-1598 cells invasion and migration. Further, RPL22L1 over-expression up-regulated the mesenchymal markers vimentin, fibronectin, and α-SMA, reduced expression of the epithelial markers E-cadherin, α-catenin, and β-catenin. RPL22L1 inhibition reduced expression of vimentin and N-cadherin. These results suggest that RPL22L1 induces epithelial-to-mesenchymal transition (EMT). Our data showed that the DMs amplified gene RPL22L1 is critical in maintaining the aggressive phenotype of OC and in triggering cell metastasis by inducing EMT. It could be employed as a novel prognostic marker and/or effective therapeutic target for OC.

Ribosomal proteins as novel players in tumorigenesis

Ribosome biogenesis is the most demanding energetic and metabolic expenditure of the cell. The nucleolus, a nuclear compartment, coordinates rRNA transcription, maturation, and assembly into ribosome subunits. The transcription process is highly coordinated with ribosome biogenesis. In this context, ribosomal proteins (RPs) play a crucial role. In the last decade, an increasing number of studies have associated RPs with extraribosomal functions related to proliferation. Importantly, the expression of RPs appears to be deregulated in several human disorders due, at least in part, to genetic mutations. Although the deregulation of RPs in human malignancies is commonly observed, a more complex mechanism is believed to be involved, favoring the tumorigenic process, its progression and metastasis. This review explores the roles of the most frequently mutated oncogenes and tumor suppressor genes in human cancer that modulate ribosome biogenesis, including their interaction with RPs. In this regard, we propose a new focus for novel therapies.

Ribosomal proteins and human diseases: pathogenesis, molecular mechanisms, and therapeutic implications

Ribosomes are essential components of the protein synthesis machinery. The process of ribosome biogenesis is well organized and tightly regulated. Recent studies have shown that ribosomal proteins (RPs) have extraribosomal functions that are involved in cell proliferation, differentiation, apoptosis, DNA repair, and other cellular processes. The dysfunction of RPs has been linked to the development and progression of hematological, metabolic, and cardiovascular diseases and cancer. Perturbation of ribosome biogenesis results in ribosomal stress, which triggers activation of the p53 signaling pathway through RPs-MDM2 interactions, resulting in p53-dependent cell cycle arrest and apoptosis. RPs also regulate cellular functions through p53-independent mechanisms. We herein review the recent advances in several forefronts of RP research, including the understanding of their biological features and roles in regulating cellular functions, maintaining cell homeostasis, and their involvement in the pathogenesis of human diseases. We also highlight the translational potential of this research for the identification of molecular biomarkers, and in the discovery and development of novel treatments for human diseases.

Mitochondrial proteomic analysis of ecdysterone protection against oxidative damage in human lens epithelial cells

AIM

To investigate the protective effects of the natural medicinal monomer ecdysterone (ECR) with estrogenic activity against oxidative damage in human lens epithelial cells B3 (HLE-B3) caused by hydrogen peroxide 21(H2O2) and to pursue the possible mitochondrial proteomic regularity of the protective effects.

METHODS

HLE-B3 cells were treated with H2O2 (300µmol/L), β-estuarial (E2; 10(-8)mol/L) and H2O2, ECR (10(-6)mol/L) and H2O2, or left untreated. Altered expression of all mitochondrial proteins was analyzed by protein array and surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS). The mass/charge (M/Z) ratios of each peak were tested by the Kruskal-Wallis rank sum test, and the protein peak value of the M/Z ratio for each treatment by pair comparison was analyzed with the Nemenyi test.

RESULTS

H2O2 up-regulated expression of two protein spots (with M/Z of 6 532 and 6 809). When E2 mitigated the oxidative damage, the expression of one protein spot (M/Z 6 532) was down-regulated. In contrast, ECR down-regulated both of protein spots (M/Z 6 532 and 6 809).

CONCLUSION

ECR could effectively inhibite H2O2 induced oxidative damage in HLE-B3 cells. The protein spot at M/Z of 6 532 might be the target spot of ECR against oxidative damage induced by H2O2.

Identification of a motif in BMRP required for interaction with Bcl-2 by site-directed mutagenesis studies

Bcl-2 is an anti-apoptotic protein that inhibits apoptosis elicited by multiple stimuli in a large variety of cell types. BMRP (also known as MRPL41) was identified as a Bcl-2 binding protein and shown to promote apoptosis. Previous studies indicated that the amino-terminal two-thirds of BMRP contain the domain(s) required for its interaction with Bcl-2, and that this region of the protein is responsible for the majority of the apoptosis-inducing activity of BMRP. We have performed site-directed mutagenesis analyses to further characterize the BMRP/Bcl-2 interaction and the pro-apoptotic activity of BMRP. The results obtained indicate that the 13-17 amino acid region of BMRP is necessary for its binding to Bcl-2. Further mutagenesis of this motif shows that amino acid residue aspartic acid (D) 16 of BMRP is essential for the BMRP/Bcl-2 interaction. Functional analyses conducted in mammalian cells with BMRP site-directed mutants BMRP(13Ala17) and BMRP(D16A) indicate that these mutants induce apoptosis through a caspase-mediated pathway, and that they kill cells slightly more potently than wild-type BMRP. Bcl-2 is still able to counteract BMRP(D16A)-induced cell death significantly, but not as completely as when tested against wild-type BMRP. These results suggest that the apoptosis-inducing ability of wild-type BMRP is blocked by Bcl-2 through several mechanisms.

SAGE analysis highlights the putative role of underexpression of ribosomal proteins in GH-secreting pituitary adenomas

BACKGROUND

Although the molecular pathogenesis of pituitary adenomas has been assessed by several different techniques, it still remains partially unclear. Ribosomal proteins (RPs) have been recently related to human tumorigenesis, but they have not yet been evaluated in pituitary tumorigenesis.

OBJECTIVE

The aim of this study was to introduce serial analysis of gene expression (SAGE), a high-throughput method, in pituitary research in order to compare differential gene expression.

METHODS

Two SAGE cDNA libraries were constructed, one using a pool of mRNA obtained from five GH-secreting pituitary tumors and another from three normal pituitaries. Genes differentially expressed between the libraries were further validated by real-time PCR in 22 GH-secreting pituitary tumors and in 15 normal pituitaries.

RESULTS

Computer-generated genomic analysis tools identified 13,722 and 14,993 exclusive genes in normal and adenoma libraries respectively. Both shared 6497 genes, 2188 were underexpressed and 4309 overexpressed in tumoral library. In adenoma library, 33 genes encoding RPs were underexpressed. Among these, RPSA, RPS3, RPS14, and RPS29 were validated by real-time PCR.

CONCLUSION

We report the first SAGE library from normal pituitary tissue and GH-secreting pituitary tumor, which provide quantitative assessment of cellular transcriptome. We also validated some downregulated genes encoding RPs. Altogether, the present data suggest that the underexpression of the studied RP genes possibly collaborates directly or indirectly with other genes to modify cell cycle arrest, DNA repair, and apoptosis, leading to an environment that might have a putative role in the tumorigenesis, introducing new perspectives for further studies on molecular genesis of somatotrophinomas.

A new PICTure of nucleolar stress

Cell growth demands new protein synthesis, which requires nucleolar ribosomal functions. Ribosome biogenesis consumes a large proportion of the cell's resources and energy, and so is tightly regulated through an intricate signaling network to guarantee fidelity. Thus, events that impair ribosome biogenesis cause nucleolar stress. In response to this stress, several nucleolar ribosomal proteins (RPs) translocate to the nucleoplasm and bind to MDM2. MDM2-mediated ubiquitination and degradation of the tumor suppressor p53 is then blocked, resulting in p53 accumulation and the induction of p53-dependent cell cycle arrest and apoptosis. Nucleolar stress is therefore a quality control surveillance mechanism that monitors the synthesis and assembly of the rRNA and protein components of ribosomes. Although nucleolar stress signaling pathways have been extensively analyzed, critical questions remain about their regulatory mechanisms. For example, how do RPs translocate from the nucleolus to the nucleoplasm to exert their functions, and do these p53-regulating RPs influence the prognosis of human cancer patients? Our laboratory recently identified the nucleolar protein PICT1 as a novel regulator of nucleolar stress. PICT1 sequesters the ribosomal protein RPL11 in the nucleolus, preventing it from binding to MDM2. MDM2 is then free to degrade p53, favoring tumor cell growth. Accordingly, the level of PICT1 in a tumor is becoming a useful prognostic marker for human cancers. This review summarizes the evidence that links nucleolar stress to tumorigenesis, and casts PICT1 as an oncogenic player in human cancer biology.

Deletion mutational analysis of BMRP, a pro-apoptotic protein that binds to Bcl-2

Bcl-2 is an anti-apoptotic member of the Bcl-2 family of proteins that protects cells from apoptosis induced by a large variety of stimuli. The protein BMRP (MRPL41) was identified as a Bcl-2 binding partner and shown to have pro-apoptotic activity. We have performed deletion mutational analyses to identify the domain(s) of Bcl-2 and BMRP that are involved in the Bcl-2/BMRP interaction, and the region(s) of BMRP that mediate its pro-apoptotic activity. The results of these studies indicate that both the BH4 domain of Bcl-2 and its central region encompassing its BH1, BH2, and BH3 domains are required for its interaction with BMRP. The loop region and the transmembrane domain of Bcl-2 were found to be dispensable for this interaction. The Bcl-2 deletion mutants that do not interact with BMRP were previously shown to be functionally inactive. Deletion analyses of the BMRP protein delimited the region of BMRP needed for its interaction with Bcl-2 to the amino-terminal two-thirds of the protein (amino acid residues 1-92). Further deletions at either end of the BMRP(1-92) truncated protein resulted in lack of binding to Bcl-2. Functional studies performed with BMRP deletion mutants suggest that the cell death-inducing domains of the protein reside mainly within its amino-terminal two-thirds. The region of BMRP required for the interaction with Bcl-2 is very relevant for the cell death-inducing activity of the protein, suggesting that one possible mechanism by which BMRP induces cell death is by binding to and blocking the anti-apoptotic activity of Bcl-2.

RPL41, a small ribosomal peptide deregulated in tumors, is essential for mitosis and centrosome integrity

Ribosomal large subunit protein RPL41 is a basic (positively charged) peptide consisting of only 25 amino acids. An antisense-based functional screening revealed that the down-regulation of RPL41 led to an anchorage-independent growth of NIH3T3 cells in soft agar plates. RPL41 depletion with gene-specific small interfering RNA also resulted in malignant transformation of NIH3T3 cells including increased tumor growth in mice. RPL41 deletion was detected in 59% of tumor cell lines by fluorescence in situ hybridization analyses and RPL41 down-regulation in 75% of primary breast cancers by real-time quantitative reverse transcription-polymerase chain reaction. These studies suggest a tumor suppression role for RPL41. By mass spectrometry, RPL41 was associated with several cytoskeleton components including tubulin beta, gamma, and myosin IIA, which was confirmed by Western blot analysis on both cellular lysis and individually in vitro-expressed proteins. RPL41 also bound directly to polymerized tubulins. Cells overexpressing a GFP-RPL41 were resistant to nocodazole-induced microtubule depolymerization. A synthetic RPL41 induced cellular alpha-tubulin acetylation and G(2)/M cell cycle arrest. These results indicate a stabilizing role of RPL41 on microtubule. Microtubule spindles are essential for chromosome segregation during mitosis. Cells with RPL41 knock-down showed abnormal spindles, frequent failure of cytokinesis, and formation of polynuclear cells. In interphase cells, RPL41-depleted cells had premature splitting of centrosome. Our results provide evidence that RPL41 is a microtubule-associated protein essential for functional spindles and for the integrity of centrosome and that the abnormal mitosis and disrupted centrosome associated with the RPL41 down-regulation may be related to malignant transformation.

How common are extraribosomal functions of ribosomal proteins?

Ribosomal proteins are ubiquitous, abundant, and RNA binding: prime candidates for recruitment to extraribosomal functions. Indeed, they participate in balancing the synthesis of the RNA and protein components of the ribosome itself. An exciting new story is that ribosomal proteins are sentinels for the self-evaluation of cellular health. Perturbation of ribosome synthesis frees ribosomal proteins to interface with the p53 system, leading to cell-cycle arrest or to apoptosis. Yet in only a few cases can we clearly identify the recruitment of ribosomal proteins for other extraribosomal functions. Is this due to a lack of imaginative evolution by cells and viruses, or to a lack of imaginative experiments by molecular biologists?

Gene expression profiling in practitioners of Sudarshan Kriya

BACKGROUND

The rapid pace of life, eating habits, and environmental pollution have increased stress levels and its related disorders. The complex molecular response to stress is mediated by stress genes and a variety of regulatory pathways. Oxidative stress is internal damage caused by reactive oxygen species. Increasing evidence suggests that chronic psychosocial stress may increase oxidative stress, which in turn may contribute to aging, and etiology of coronary diseases, cancer, arthritis, etc. Psychophysiological concomitants of meditation have been extensively researched, but there are very little data available on biochemical activity leading to relieving stress by causing a relaxation response by Sudarshan Kriya (SK). SK is a breathing technique that involves breathing in three different rhythms. It is preceded by Ujjayi Pranayam (long and deep breaths with constriction at the base of throat) and Bhastrika (fast and forceful breaths through nose along with arm movements).

METHODS

Forty-two SK practitioners and 42 normal healthy controls were recruited for our study. The practitioners had practiced SK for at least 1 year. Selected normal healthy controls did not perform any conventional physical exercise or any formal stress management technique. Whole blood was used for glutathione peroxidase estimation and red blood cell lysate was used for superoxide dismutase activity assay and for glutathione estimation. White blood cells were isolated from fresh blood and assayed for gene expression using reverse transcriptase-polymerase chain reaction. The parameters studied are antioxidant enzymes, genes involved in oxidative stress, DNA damage, cell cycle control, aging, and apoptosis.

RESULTS

A better antioxidant status both at the enzyme activity and RNA level was seen in SK practitioners. This was accompanied by better stress regulation and better immune status due to prolonged life span of lymphocytes by up-regulation of antiapoptotic genes and prosurvival genes in these subjects.

CONCLUSIONS

Our pilot study provides the first evidence suggesting that SK practice may exert effects on immunity, aging, cell death, and stress regulation through transcriptional regulation.

Differentiation of the bovine dominant follicle from the cohort upregulates mRNA expression for new tissue development genes

This study was designed to identify genes that regulate the transition from FSH- to LH-dependent development in the bovine dominant follicle (DF). Serial analysis of gene expression (SAGE) was used to compare the transcriptome of granulosa cells isolated from the most oestrogenic growing cohort follicle (COH), the newly selected DF and its largest subordinate follicle (SF) which is destined for atresia. Follicle diameter, follicular fluid oestradiol (E) and E:progesterone ratio confirmed follicle identity. Results show that there are 93 transcript species differentially expressed in DF granulosa cells, but only 8 of these encode proteins known to be involved in DF development. Most characterised transcripts upregulated in the DF are from tissue development genes that regulate cell differentiation, proliferation, apoptosis, signalling and tissue remodelling. Semiquantitative real-time PCR analysis confirmed seven genes with upregulated (P≤0.05) mRNA expression in DF compared with both COH and SF granulosa cells. Thus, the new genes identified by SAGE and real-time PCR, which show enhanced mRNA expression in the DF, may regulate proliferation (cyclin D2;CCND2), prevention of apoptosis or DNA damage (growth arrest and DNA damage-inducible, β;GADD45B), RNA synthesis (splicing factor, arginine/serine rich 9;SFRS9) and unknown processes associated with enhanced steroidogenesis (ovary-specific acidic protein; DQ004742) in granulosa cells of DF at the onset of LH-dependent development. Further studies are required to show whether the expression of identified genes is dysregulated when abnormalities occur during DF selection or subsequent development.

Identification of genes differentially expressed during larval molting and metamorphosis of Helicoverpa armigera

BACKGROUND

Larval molting and metamorphosis are important physiological processes in the life cycle of the holometabolous insect. We used suppression subtractive hybridization (SSH) to identify genes differentially expressed during larval molting and metamorphosis.

RESULTS

We performed SSH between tissues from a variety of developmental stages, including molting 5th and feeding 6th instar larvae, metamorphically committed and feeding 5th instar larvae, and feeding 5th instar and metamorphically committed larvae. One hundred expressed sequence tags (ESTs) were identified and included 73 putative genes with similarity to known genes, and 27 unknown ESTs. SSH results were further characterized by dot blot, Northern blot, and RT-PCR. The expression levels of eleven genes were found to change during larval molting or metamorphosis, suggesting a functional role during these processes.

CONCLUSION

These results provide a new set of genes expressed specifically during larval molt or metamorphosis that are candidates for further studies into the regulatory mechanisms of those stage-specific genes during larval molt and metamorphosis.

Protective effect of vineatrol against kainic acid induced seizures, oxidative stress and on the expression of heat shock proteins in rats

The aim of the present study was to evaluate the effect of an antioxidant vineatrol against kainic acid-induced seizures, markers of oxidative stress and expression of heat shock protein in brain. In rats, kainic acid (10 mg/kg i.p.) induced long lasting seizures, associated behavioral symptoms and brain damage and significantly increased level of brain malondialdehyde (MDA) (283 +/- 42 nmol/g wet tissue) as compared to control (173.3 +/- 10.2 nmol/g wet tissue). Pretreatment (5 min) of vineatrol (10, 20 and 40 mg/kg i.p.) could not inhibit the convulsions though the latency was significantly increased with 20 and 40 mg/kg. However when the drug was administrated 5 min prior and repeated at 30 and 90 min after kainic acid there was significant reduction in incidence of convulsions. The brain MDA levels were also found to be significantly attenuated, however the glutathione levels were not different in control, kainic acid and vineatrol treated animals. Expression of heat shock protein (HSP) 72 was observed in the kainic acid per se group indicating neurotoxicity as compared to the control group and was reduced by vineatrol. The study suggests the potential use of vineatrol in status epilepticus.

BMRP is a Bcl-2 binding protein that induces apoptosis

Members of the Bcl-2 family of proteins play important roles in the regulation of cell death by apoptosis. The yeast Two-Hybrid system was utilized to identify a protein that interacts with the anti-apoptotic protein Bcl-2, designated BMRP. This protein corresponds to a previously known mitochondrial ribosomal protein (MRPL41). Binding experiments confirmed the interaction of BMRP to Bcl-2 in mammalian cells. Subcellular fractionation by differential centrifugation studies showed that both Bcl-2 and BMRP are localized to the same fractions (fractions that are rich in mitochondria). Northern blot analysis revealed a major bmrp mRNA band of approximately 0.8 kb in several human tissues. Additionally, a larger 2.2 kb mRNA species was also observed in some tissues. Western blot analysis showed that endogenous BMRP runs as a band of 16-17 kDa in SDS-PAGE. Overexpression of BMRP induced cell death in primary embryonic fibroblasts and NIH/3T3 cells. Transfection of BMRP showed similar effects to those observed by overexpression of the pro-apoptotic proteins Bax or Bad. BMRP-stimulated cell death was counteracted by co-expression of Bcl-2. The baculoviral caspase inhibitor p35 also protected cells from BMRP-induced cell death. These findings suggest that BMRP is a mitochondrial ribosomal protein involved in the regulation of cell death by apoptosis, probably affecting pathways mediated by Bcl-2 and caspases.

cDNA representational difference analysis of ileal Peyer’s patches in lambs after oral inoculation with scrapie

cDNA representational difference analysis (RDA) was used to study gene expression profiles in the ileal Peyer's patch of a lamb 1 week after oral inoculation with the scrapie agent. Twenty-five differentially expressed cDNA fragments were identified and cloned. Sequence analysis indicated seven novel gene sequences. Other clones shared sequence homology with genes encoding ribosomal and mitochondrial proteins, the translation initiation factor EIF4GII and the bovine pancreatic thread protein. Reverse Northern was used to confirm the differential expression in another four lambs inoculated with scrapie and the tissue distribution of the novel genes was examined using Northern blot analysis.

Weak electromagnetic fields (50 Hz) elicit a stress response in human cells

The aim of this study was to demonstrate the expression of heat shock (HS) genes in human cells in response to extremely low-frequency electromagnetic fields (ELF-EMF) alone and in combination with thermal stress. After exposing human myeloid leukemia (HL-60) cells to the stressor(s) for 30 min we quantified the expression of the HS genes HSP27, HSP60, HSP70 (A, B, and C), HSC70, HSP75, HSP78, and HSP90 (alpha and beta) by RT-PCR. The results clearly show that HS genes, in particular the three HSP70 genes (A, B, and C), are induced by ELF-EMF, a reaction that is enhanced by simultaneous HS (43 degrees C for 30 min). The results show similarities and some significant differences to previous experiments in which transgenic nematodes were used to monitor the induction of the HSP70 gene under similar stress conditions. We also studied the effect of different flux densities on gene expression in the range of 10-140 microT. Even the lowest dose tested (10 microT) resulted in a significant induction of the genes HSP70A, HSP70B, and HSP70C. The reaction to ELF-EMF shows a maximum at a flux density of 60-80 microT. The unusual dose-response relation reveals an interesting difference to other stressors that elicit the HS response.

Alterations in mRNA expression of ribosomal protein S9 in hydrogen peroxide-treated neurotumor cells and in rat hippocampus after transient ischemia

This study was designed to isolate new genes related to apoptosis in rat pheochromocytoma (PC12) cells treated with hydrogen peroxide (H2O2), and to characterize the roles of the genes using both in vitro and in vivo models of oxidative injury. cDNA libraries were prepared from H2O2-treated and -untreated PC12 cells, and a ribosomal protein S9 (RPS9) clone was isolated by a differential screening method. Increase of RPS9 expression in both H2O2-treated PC12 and neuroblastoma (Neuro-2A) cells was shown by Northern blot analysis. Viability of the antisense-transfected Neuro-2A (RPS9-AS) cells following H2O2 treatment was significantly reduced in a dose-dependent manner. In an in vivo model of transient forebrain ischemia, an increase in RPS9 expression was prominent by 1 day postischemia in the granule cell layer neurons of the dentate gyrus. Both activation of caspase-3 and significant recovery of viability following pretreatment with cycloheximide were shown in RPS9-AS cells treated with H2O2. These data suggest that RPS9 plays a protective role in oxidative injury of neuronal cells.

S29 ribosomal protein induces apoptosis in H520 cells and sensitizes them to chemotherapy

Non-small cell lung cancer (NSCLC) is the most prevalent type of lung cancer especially in India and displays resistance to anticancer treatment. In our earlier study we had isolated a cDNA clone from rat thymocytes induced to undergo apoptosis, which was found to encode S29 ribosomal protein [Biochem. Biophys. Res. Commun. 277 (2000) 476]. In the present study an attempt has been made to find out whether enhanced expression of S29 cDNA can kill NSCLC H520 cells. We found that S29 induced apoptosis and augmented the effect of anticancer drugs. Expressions of several molecular determinants of apoptosis were analyzed in order to understand the mechanism of apoptosis induced by S29. We observed downregulation of the expression of inhibitors of apoptosis proteins (IAPs) Bcl-2, Bcl-X(L), and survivin and upregulation of pro-apoptotic p53 and Bax as assessed by Western blotting. Mitochondrial release of cytochrome c and activation of initiator caspase-8 and -9 and effector caspase-3, followed by cleavage of nuclear substrate poly(ADP-ribose) polymerase, were also observed. Permeability transition as determined by changes in DeltaPsi(m) was not a requirement for cytochrome c release. There was a marginal increase in the release of apoptosis inducing factor (AIF) and reduction of NF-kappaB dependent transcriptional activity. There was non-involvement of calcium and the telomerase activity, a proliferation marker.

Primary effect of chemotherapy on the transcription profile of AIDS-related Kaposi's sarcoma

BACKGROUND

Drugs & used in anticancer chemotherapy have severe effects upon the cellular transcription and replication machinery. From in vitro studies it has become clear that these drugs can affect specific genes, as well as have an effect upon the total transcriptome.

METHODS

Total mRNA from two skin lesions from a single AIDS-KS patient was analyzed with the SAGE (Serial Analysis of Gene Expression) technique to assess changes in the transcriptome induced by chemotherapy. SAGE libraries were constructed from material obtained 24 (KS-24) and 48 (KS-48) hrs after combination therapy with bleomycin, doxorubicin and vincristine. KS-24 and KS-48 were compared to SAGE libraries of untreated AIDS-KS, and to libraries generated from normal skin and from isolated CD4+ T-cells, using the programs USAGE and HTM. SAGE libraries were also compared with the SAGEmap database.

RESULTS

In order to assess the primary response of AIDS-related Kaposi's sarcoma (AIDS-KS) to chemotherapy in vivo, we analyzed the transcriptome of AIDS-KS skin lesions from a HIV-1 seropositive patient at two time points after therapy. The mRNA profile was found to have changed dramatically within 24 hours after drug treatment. There was an almost complete absence of transcripts highly expressed in AIDS-KS, probably due to a transcription block. Analysis of KS-24 suggested that mRNA pool used in its construction originated from poly(A) binding protein (PABP) mRNP complexes, which are probably located in nuclear structures known as interchromatin granule clusters (IGCs). IGCs are known to fuse after transcription inhibition, probably affecting poly(A)+RNA distribution.Forty-eight hours after chemotherapy, mRNA isolated from the lesion was largely derived from infiltrating lymphocytes, confirming the transcriptional block in the AIDS-KS tissue.

CONCLUSIONS

These in vivo findings indicate that the effect of anti-cancer drugs is likely to be more global than up- or downregulation of specific genes, at least in this single patient with AIDS-KS. The SAGE results obtained 24 hrs after chemotherapy can be most plausibly explained by the isolation of a fraction of more stable poly(A)+RNA.

Insights into the molecular mechanism of apoptosis induced by TNF-alpha in mouse epidermal JB6-derived RT-101 cells

The mammalian response to stress is complex, often involving multiple signaling pathways that act in concert to influence cell fate. To examine potential interaction between the signaling cascade, we have focused on the effects of a model apoptotic system in a single cell type sensitive to TNF-alpha induced apoptosis through an examination of the relative influences of MAPKs as well as transcription factors AP-1, NF-kappaB, and various survival genes in determining apoptosis. Our results show that ERKs decreased transiently or remain unchanged, JNK decreased robustly, whereas c-Jun increased transiently, thereby indicating that members of MAPK family are differentially regulated in response to TNF-alpha induced apoptosis, whereas NF-kappaB protein expression decreased transiently and activity decreased at 24 h post-treatment. The survival genes Bcl-2, Bcl-XL, and survivin act independently and downstream of ERK and JNK to decrease the survival of TNF-alpha treated RT-101 cells. The results also suggest the involvement of the mitochondria and cytochrome c. Caspase-3 appears to be a part of a downstream event.

Nerve growth factor selectively regulates expression of transcripts encoding ribosomal proteins

BACKGROUND

NGF exerts a variety of actions including promotion of neuronal differentiation and survival. The PC12 rat pheochromocytoma cell line has proved valuable for studying how NGF works and has revealed that the NGF mechanism includes regulation of gene expression. Accordingly, we used SAGE (Serial Analysis of Gene Expression) to compare levels of specific transcripts in PC12 cells before and after long-term NGF exposure. Of the approximately 22,000 transcripts detected and quantified, 4% are NGF-regulated by 6-fold or more. Here, we used database information to identify transcripts in our SAGE libraries that encode ribosomal proteins and have compared the effect of NGF on their relative levels of expression.

RESULTS

Among the transcripts detected in our SAGE analysis, 74 were identified as encoding ribosomal proteins. Ribosomal protein transcripts were among the most abundantly expressed and, for naive and NGF-treated PC12 cells, represented 5.2% and 3.5%, respectively, of total transcripts analyzed. Surprisingly, nearly half of ribosomal protein transcripts underwent statistically significant NGF-promoted alterations in relative abundance, with changes of up to 5-fold. Of the changes, approximately 2/3 represented decreases. A time course revealed that the relative abundance of transcripts encoding RPL9 increases within 1 hr of NGF treatment and is maximally elevated by 8 hr.

CONCLUSIONS

These data establish that NGF selectively changes expression of ribosomal protein transcripts. These findings raise potential roles for regulation of ribosomal protein transcripts in NGF-promoted withdrawal from the cell cycle and neuronal differentiation and indicate that regulation of individual ribosomal protein transcripts is cell- and stimulus-specific.

Vitamin C augments chemotherapeutic response of cervical carcinoma HeLa cells by stabilizing P53

Human Papilloma Virus (HPV) is associated in most instances with cervical cancer. The HPV oncoproteins target P53 protein for degradation, leading to deregulation of cell cycle. We investigated whether stabilization of P53 in cervical cancer cells, by downregulating HPV transcription would restore the apoptotic ability of these cells. Our findings show that vitamin C downregulates the redox sensitive transcription factor AP-1 and decreases one of its transcription targets HPV E6, and stabilizes P53. This was associated with an increase in Bax and decrease in Bcl-2 and telomerase activity. Accumulation of P53 and its target gene bax then sensitized HeLa cells to cell-cycle arrest, cell death/apoptosis induced by cisplatin, and etoposide. Increasing drug sensitivity of cervical carcinoma cells by stabilizing P53 using vitamin C is a novel approach and has potential clinical relevance.