Csa-19, a radiation-responsive human gene, identified by an unbiased two-gel cDNA library screening method in human cancer cells

Effect of the interaction between ribosomal protein L10a and insulin receptor on carbohydrate metabolism

The number of patients with insulin-resistant diabetes has significantly increased. Thus, alternative insulin mimetics are required for such patients. Some evidences indicate that ribosomal protein L10a (RpL10a) is involved in the insulin pathway. In addition, we previously demonstrated that recombinant RpL10a from Fenneropenaeus merguiensis (Fm-RpL10a) could stimulate cell proliferation and trehalose metabolism in RpL10a–over-expressing flies by inducing insulin receptor (InR) expression and some insulin signaling mediators phosphorylation. In this study, we investigated the in silico binding between Fm-RpL10a and InR. The results indicated that Fm-RpL10a bound to InR at residues 635–640 and 697–702 of the FnIII2 domain. This binding was confirmed using a pull-down and immunofluorescence assay. Further analysis indicated that Fm-RpL10a could stimulate glucose utilisation by insulin-resistant cells (IRCs) and healthy cells. Additionally, Fm-RpL10a at a low concentration (1 μg/ml) altered some glucose metabolism-related genes expression in Fm-RpL10a treated IRCs. The qRT-PCR result revealed the up-regulation of Hk1, which encode key enzymes in glycolysis. Conversely, the expression of G6pc3, which participates in gluconeogenesis, was down-regulated. Overall, the results suggest that Fm-RpL10a can alleviate insulin resistance by stimulating insulin signaling via the FnIII2 domain of InR and activate glycolysis. Therefore, Fm-RpL10a may be a candidate insulin mimetic for the treatment of diabetes.

Ribosomal protein L10A and signaling pathway

Ribosome: machinery in control of messenger RNA's (mRNAs) and several ribosomal proteins are in the small and large subunit of the ribosome. Various aspects of ribosomal proteins have related to cell growth, cell cycle, and diseases. Ribosomal protein L10A (RpL10A) in shrimp and fruit fly has been demonstrated to play a role in oogenesis. Interestingly, deletion RpL10A gene (RpL10Ab^-/-) germ line clone of the fruit fly showed a loss of follicle cells surrounding the egg chamber, but nurse cells appeared normal. This phenotype is reminiscent of insulin receptor mutants (InR^-/-). In contrast, over-expression of RpL10A in the eyes of the fruit flies resulted in abnormal ommatidia with a loss of red pigment in the center of the eyes. In this study, the abnormal rearrangements of nuclei and lack of cell membranes in those eyes were demonstrated. Furthermore, the expression of InR gene and the InR protein were extensively increased as determined by real-time PCR and immunohistochemistry, respectively. In addition, some insulin signaling mediators were also detected. The Akt and FOXO proteins were highly phosphorylated in the RpL10A over-expressed mutant. The results revealed that RpL10A induced over-expression of the insulin receptor and consequently activated in insulin signaling pathway which affects cell proliferation and we suggest RpL10A stimulates cell proliferation via the insulin signaling pathway.

Expression profile of ribosomal protein L10a throughout gonadal development in rainbow trout (Oncorhynchus mykiss)

Ribosomal protein L10a (RpL10A) has been previously established as a stimulator during the early stages of ovarian development in both the banana prawn and the fruit fly. In order to develop a greater understanding of the role of this protein in vertebrates, the present study aimed to characterize the expression profile of rpl10a during gonadal development in fish. It was determined that the expression of rpl10a within genital ridges increased during embryonic development. Although rpl10a expression was observed in both gonadal somatic cells and primordial germ cells, higher levels of both transcript and protein expression were detected in somatic cells. rpl10a transcripts were observed in all of the adult tissues examined. Cellular level expression of rpl10a was subsequently characterized across various maturational stages using in situ hybridization and immunohistochemistry of both testes and ovaries. Analysis of tissue derived from the testis showed high levels of rpl10a expression within spermatogonia and the Sertoli cells attached to them. In ovarian tissue, rpl10a was strongly expressed in chromatin-nucleolus-stage and peri-nucleolus-stage oocytes. The relationship between rpl10a expression and regulation of gonadal development was confirmed using real-time PCR, which was performed in order to analyze rpl10a expression in testicular and ovarian tissues subsequent to incubation with salmon pituitary extract and various sex steroids for 24 h. Among them, 11-ketotestosterone at 100 ng/mL effectively up-regulated expression of rpl10a in testicular tissues, while 17β-estradiol down-regulated rpl10a expression in ovarian tissues. These results suggested that rpl10a played a role in the regulation of gonadal development in fish.

RpL10A regulates oogenesis progression in the banana prawn Fenneropenaeus merguiensis and Drosophila melanogaster

To develop banana prawn (Fenneropenaeus merguiensis) aquaculture, the mechanism of ovarian maturation is under investigation. In a previous study, we reported the RpL10A protein as an ovarian maturation stimulator. To further investigate the function of RpL10A, we turned to the fruit fly (Drosophila melanogaster) to take advantage of the genetic tools available. Here, we elucidate the expression and function of RpL10A in the D. melanogaster ovary. RpL10A is expressed in the cytoplasm of both nurse and follicle cells throughout oogenesis. While shrimp have one RpL10A gene, D. melanogaster has two genes, RpL10Aa and RpL10Ab. RpL10Ab displays more similarity with shrimp RpL10A and was further investigated. RpL10Ab homozygous mutants are lethal and germline clone analysis showed that RpL10Ab is an essential gene in oogenesis. Moreover, RpL10Ab(-) germline clones resulted in premature death of the follicle cells. This phenotype is reminiscent of some insulin pathway mutants, suggesting that RpL10Ab may be involved in the insulin signaling pathway. In addition, RpL10Ab(-) follicle cells showed abnormal nuclei and membranes. Shrimp RpL10A rescued RpL10Ab homozygous mutants, revealing their functional conservation. Surprisingly, we found cell death in multiple tissues when RpL10A was over-expressed, suggesting that proper RpL10A levels are important. This research reveals novel findings about the role of RpL10A during oogenesis and may, in the future, lead to new approaches to stimulate ovarian development in shrimp.

Characterization and biological activity of the ribosomal protein L10a of the white shrimp: Fenneropenaeus merguiensis De Man during vitellogenesis

The molecular events in the ovaries of Fenneropenaeus merguiensis De Man during vitellogenesis were investigated. The ribosomal protein L10a (RPL10a) was characterized and cloned. It consisted of 669 bp and the deduced polypeptide had 217 amino acids (GeneBank/EBI accession number FJ623402). The calculated molecular mass and pI were 25.7 kDa and 10.06, respectively. An immunohistochemical technique showed that RPL10a was located in the cytoplasm and nucleus of developing oocytes and follicle cells. Treatment of undeveloped ovarian explant cultures with recombinant histidine (His)-RPL10a stimulated the expression of translationally controlled tumor protein (TCTP), heat shock protein 70 (HSP70), and shrimp ovarian peritrophin (SOP) genes, previously shown to be involved in ovarian maturation. The transcripts of all three genes in the ovarian explants showed their highest expression after 4 h incubation with the His-RPL10a at 37 degrees C. The TCTP and HSP70 transcripts declined after 12 h, while the transcript of SOP remained high until 24 h. The His-RPL10a did not stimulate the expression of the TCTP, SOP, and HSP70 genes in shrimp muscle tissue. The information on the molecular behavior of the RPL10a in this study may, in the future, lead to new methods to stimulate ovarian development in shrimp.

Ribosomal protein L10a, a bridge between trichosanthin and the ribosome

Trichosanthin is a type I ribosome-inactivating protein with many pharmacological activities. The trichosanthin-coupled Sepharose affinity purification revealed a protein, which was identified by mass spectrometry as the ribosomal protein L10a. The interaction between trichosanthin and recombinant L10a was further confirmed by in vitro binding assay. Kinetic analysis by surface plasmon resonance technology revealed that L10a had a high affinity to trichosanthin with a K(D) of 7.78nM. The study with mutated forms of trichosanthin demonstrated that this specific association correlates with the ribosome-inactivating activity of trichosanthin. This finding might provide insight into the mechanisms by which trichosanthin inactivates ribosome and that underlies its pharmacological effect.

Biological factors influencing the RBE of neutrons: implications for their past, present and future use in radiotherapy

The recent resurgence of interest in fast-neutron therapy, particularly for the treatment of prostate cancer, warrants a review of the original radiobiological basis for this modality and the evolution of these concepts that resulted from subsequent experimentation with the fast-neutron beams used for randomized clinical trials. It is clear from current radiobiological knowledge that some of the postulates that formed the mechanistic basis for past clinical trials were incorrect. Such discrepancies, along with the inherent physical disadvantages of neutron beams in terms of collimation and intensity modulation, may partially account for the lack of therapeutic benefit observed in many randomized clinical trials. Moreover, it is equally apparent that indiscriminate prescription of fast-neutron therapy is likely to lead to an adverse clinical outcome in a proportion of patients. Hence any renewed efforts to establish a niche for this modality in clinical radiation oncology will necessitate the development of a triage system that can discriminate those patients who might benefit from fast-neutron therapy from those who might be harmed by it. In the future, fast-neutron therapy might be prescribed based upon the relative status of appropriate molecular parameters that have a differential impact upon radiosensitivity to photons compared to fast neutrons.

Induction of apoptosis in head-and-neck squamous carcinoma cells by gamma-irradiation and bleomycin is p53-independent

We have examined the ability of gamma-irradiation and bleomycin to induce apoptosis in a model system consisting of cell lines derived from naturally occurring human head-and-neck squamous-cell carcinomas with contrasting p53 status and expression levels of pro- and anti-apoptotic molecules. Following exposure to gamma-irradiation (20 Gy) or bleomycin (3.5 microM) for 0 to 96 hr, cells expressing either transcriptionally inactive mutant p53 (HN6) or a truncated p53 molecule (HN19) underwent apoptosis, as assessed by fluorescence-activated cell sorting and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, in contrast to cells that express wild-type p53 (HN30), suggesting that apoptosis induced by these agents occurs by p53-independent mechanisms. Apoptosis in HN6 and HN19 cells was preceded by a G(2)/M cell-cycle block, as analyzed by DNA content and BrdU staining. In contrast, HN30 cells remained blocked in both G(1) and G(2)/M and failed to re-enter the cell cycle. Levels of Bcl-2 were elevated in 3 of 10 cell lines, and only marginal differences were observed for Bcl-x(L). Pro-apoptotic proteins bax and Bcl-x(S) were detectable in normal keratinocytes and 4 tumor cell lines. Bax-delta (16 kDa) was highly represented in normal keratinocytes, and levels of bak were variable between cell lines. Elevated expression of Bcl-2 failed to protect HN19 cells from either gamma-irradiation or bleomycin-induced apoptosis. Our data support the existence of p53- and Bcl-2-independent pathways regulating apoptosis in keratinocytes and suggest that efficacy of either radiotherapy or bleomycin treatment for oral squamous-cell neoplasms may not, therefore, be influenced solely by endogenous p53 status.

Expression analysis of human HL60 cells exposed to 60 Hz square- or sine-wave magnetic fields

A total of 960 complementary DNA (cDNA) clones from an HL60 cell cDNA library were screened to discover genes that were differentially expressed in HL60 cells exposed to 60 Hz square-wave magnetic fields (MFs) compared to sham-exposed cells. Square-wave fields are rich in odd harmonic frequency content. We used a two-gel cDNA library screening method (BIGEL) to identify treatment-induced alterations in gene expression. Four cDNA clones were tentatively identified as differentially expressed after exposure to square-wave MFs at 2 mT for 24 h. BIGEL-identified genes (GenBank accession number) corresponding to these clones were: TI227H (D50525), EST Homo sapiens partial cDNA (Z17814), human ribosomal protein S13 (L01124), and AICAR transformylase mRNAs (D82348). The differences in mRNA levels were not confirmed in test compared to experimental cells by Northern analysis. In other experiments, we used concurrent exposure to 60 Hz sine- or square-wave MFs (0 or 2 mT, duration of 3 or 24 h, no postexposure delay). In addition to the four BIGEL genes, we also investigated MYC, HSP70, RAN and SOD1. In the case of MYC and HSP70, square-wave MFs appeared to exhibit more marked alterations when compared to sinusoidal waveforms, but the overall results indicated no effect of possible differential magnetic-field-induced expression of all eight genes. In contrast, alterations of mRNA levels were observed for seven genes after exposure to X irradiation, hyperthermia and TPA. These results are contrary to previously proposed similarities between the action of these agents and MF effects on gene transcription.