RPLP1 Research Articles

RNAi-Mediated Knockdown of Acidic Ribosomal Stalk Protein P1 Arrests Egg Development in Adult Female Yellow Fever Mosquitoes, Aedes aegypti.

After taking a blood meal, the fat body of the adult female yellow fever mosquito, Aedes aegypti, switches from a previtellogenic state of arrest to an active state of synthesizing large quantities of yolk protein precursors (YPPs) that are crucial for egg development. The synthesis of YPPs is regulated at both the transcriptional and translational levels. Previously, we identified the cytoplasmic protein general control nonderepressible 1 (GCN1) as a part of the translational regulatory pathway for YPP synthesis. In the current study, we used the C-terminal end of GCN1 to screen for protein-protein interactions and identified 60S acidic ribosomal protein P1 (P1). An expression analysis and RNAi-mediated knockdown of P1 was performed to further investigate the role of P1 in mosquito reproduction. We showed that in unfed (absence of a blood meal) adult A. aegypti mosquitoes, P1 was expressed ubiquitously in the mosquito organs and tissues tested. We also showed that the RNAi-mediated knockdown of P1 in unfed adult female mosquitoes resulted in a strong, transient knockdown with observable phenotypic changes in ovary length and egg deposition. Our results suggest that 60S acidic ribosomal protein P1 is necessary for mosquito reproduction and is a promising target for mosquito population control.

RPLP1 Is Up-Regulated in Human Adenomyosis and Endometrial Adenocarcinoma Epithelial Cells and Is Essential for Cell Survival and Migration In Vitro.

Adenomyosis is defined as the development of endometrial epithelial glands and stroma within the myometrial layer of the uterus. These "ectopic" lesions share many cellular characteristics with endometriotic epithelial cells as well as endometrial adenocarcinoma cells, including enhanced proliferation, migration, invasion and progesterone resistance. We recently reported that the 60S acidic ribosomal protein P1, RPLP1, is up-regulated in endometriotic epithelial cells and lesion tissue where it plays a role in cell survival. To evaluate if a similar pattern of expression and function for RPLP1 exists in adenomyosis and endometrial cancer, we examined RPLP1 expression in adenomyosis and endometrial cancer tissue specimens and assessed its function in vitro using well-characterized cell lines. A total of 12 control endometrial biopsies and 20 eutopic endometrial and matched adenomyosis biopsies as well as 103 endometrial adenocarcinoma biopsies were evaluated for RPLP1 localization by immunohistochemistry. Endometrial adenocarcinoma cell lines, Ishikawa, HEC1A, HEC1B and AN3 were evaluated for RPLP1 protein and transcript expression, while in vitro function was evaluated by knocking down RPLP1 expression and assessing cell survival and migration. RPLP1 protein was up-regulated in eutopic epithelia as well as in adenomyosis lesions compared to eutopic endometria from control subjects. RPLP1 was also significantly up-regulated in endometrial adenocarcinoma tissue. Knockdown of RPLP1 in endometrial adenocarcinoma cell lines was associated with reduced cell survival and migration. RPLP1 expression is up-regulated in eutopic and ectopic adenomyotic epithelia as well as in the epithelia of endometrial cancer specimens. In vitro studies support an essential role for RPLP1 in mediating cell survival and migration, processes which are all involved in pathophysiology associated with both diseases.

Rootstock-Mediated Transcriptional Changes Associated with Cold Tolerance in Prunus mume Leaves

Japanese apricot (Prunus mume) is remarkably valuable for its high ornamental and economic importance due to its distinctive features. Low temperature is a serious environmental constraint for this species, restricting its cultivation and dispersal in the north of China. To address this issue, breeding requires an understanding of the molecular mechanisms underlying responses to cold stress. We examined the leaf physiological and transcriptome profile by RNA sequencing in ‘Bungo’ scion cultivar grafted onto Prunus mume (cold-sensitive) and Prunus armeniaca (cold-tolerant) rootstocks at 4 °C for 0, 6, and 24 h. Our results revealed that the increased MDA concentration in the leaves of P. mume cultivar (cold-sensitive) suggests that cold stress might cause oxidative damage and increased sensitivity. Moreover, the cold-tolerant cultivar (P. armeniaca) considerably enhances the enzyme activities (i.e., SOD, POD, and CAT), as well as osmo-protectants (soluble sugars and proline) compared with sensitive cultivar, which helps plants to withstand oxidative damage caused by cold stress. Additionally, differentially expressed genes were shown to be enriched in plant hormone signal transduction, ribosome, MAPK signaling, and circadian rhythm pathway. After 24 h of cold stress, genes related to PYL4, histidine kinase 1, SAUR36, bHLH130, bHLH123, TIFY 6B-like, WRKY 40, WRKY 57, and 60S acidic ribosomal protein P1 were differentially expressed, implying that these DEGs involved in multiple pathways are involved in cold tolerance in Japanese apricot. This study improved our current understanding of the mechanism of cold tolerance in Japanese apricot, and the findings could be utilized for other related fruit species.

Protein expression profiles that underpin the preventive and therapeutic potential of Moringa oleifera Lam against azoxymethane and dextran sodium sulfate-induced mouse colon carcinogenesis.

Previous studies in a mouse model have indicated the anticancer potential of boiled Moringa oleifera pod (bMO)-supplemented diets; however, its molecular mechanisms are still unclear. Therefore, the present study aimed to explore the protein expression profiles responsible for the suppressive effect of bMO supplementation on azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced mouse colon carcinogenesis. Analysis by gel electrophoresis and liquid chromatography-tandem mass spectrophotometry demonstrated that there were 125 proteins that were differentially expressed in mouse colon tissues between 14 experimental groups of mice. The differentially expressed proteins are involved in various biological processes, such as signal transduction, metabolism, transcription and translation. Venn diagram analysis of the differentially expressed proteins was performed in six selected mouse groups, including negative control, positive control mice induced by AOM/DSS, the AOM/DSS groups receiving preventive or therapeutic bMO diets and their bMO-supplemented control groups. This analysis identified 7 proteins; 60S acidic ribosomal protein P1 (Rplp1), fragile X mental retardation, cystatin 9, round spermatids protein, zinc finger protein 638, protein phosphatase 2C (Ppm1g) and unnamed protein product as being potentially associated with the preventive and therapeutic effects of bMO in AOM/DSS-induced mouse colon cancer. Analysis based on the search tool for interactions of chemicals (STITCH) database predicted that Rplp1 interacted with the apoptotic and inflammatory pathways, whereas Ppm1g was associated only with inflammatory networks. This proteomic analysis revealed candidate proteins that are responsible for the effects of bMO supplementation, potentially by regulating apoptotic and inflammatory signaling networks in colorectal cancer prevention and therapy.

60S acidic ribosomal protein P1 (RPLP1) is elevated in human endometriotic tissue and in a murine model of endometriosis and is essential for endometriotic epithelial cell survival in vitro.

Endometriosis is a female disease which is defined as the presence of ectopic endometrial tissue and is dependent on estrogen for its survival in these ectopic locations. Expression of the ribosomal protein large P1 (RPLP1) is associated with cell proliferation and invasion in several pathologies, but a role in the pathophysiology of endometriosis has not been explored. In this study, we aimed to evaluate the expression and function of RPLP1 with respect to endometriosis pathophysiology. RPLP1 protein was localised by immunohistochemistry (IHC) in eutopic and ectopic tissue from 28 subjects with confirmed endometriosis and from 20 women without signs or symptoms of the disease, while transcript levels were evaluated by qRT-PCR in 77 endometriotic lesions and 55 matched eutopic endometrial biopsies, and protein expression was evaluated using western blotting in 20 of these matched samples. To evaluate the mechanism for enhanced lesion expression of RPLP1, an experimental murine model of endometriosis was used and RPLP1 expression was localized using IHC. In vitro studies using an endometriosis cell line coupled with shRNA knockdown was used to demonstrate its role in cell survival. Expression of RPLP1 mRNA and protein were significantly higher in ectopic lesion tissue compared to paired eutopic endometrium and immunohistochemical localisation revealed predominant localisation to epithelial cells. This pattern of lesion RPLP1 was recapitulated in mice with experimentally induced endometriosis. Stable knockdown of RPLP1 protein resulted in a significant decrease in cell survival in vitro. These studies reveal that RPLP1 is associated with cell proliferation and/or survival and may play a role in the pathophysiology of endometriosis.

Bioinformatic Analysis of Differentially Expressed Genes in Peripheral Blood of Human Immunodeficiency Virus/Tubercle Bacilli Co-infected Patients.

Objective To analyze the differentially expressed genes in peripheral blood of human immunodeficiency(HIV)/tubercle bacilli co-infected patients and explore the biological regulatory mechanism and network of key proteins,so as to provide new evidence for early diagnosis and clinical treatment of HIV/TB co-infected patients. Methods Microarray gene chip data of HIV/TB co-infected patients were downloaded from public databases GEO and imported into the analysis software GEO,STRING,PANTHER,and GenClip. The gene expression profiles,protein interaction networks,processes of molecular biology,and gene functions were analyzed. Results The expression profiles of 15 529 genes between the two groups of patients were similar,and gene expression profiles from 44 subjects were highly correlated. The 251 differentially expressed genes had good diagnostic capabilities in the differential diagnosis of HIV/TB infection. RPLP1 might be a key gene in the diagnosis of HIV/TB infection. The differentially expressed genes and positive regulators showed certain functions such as external stimuli,signal transduction pathways in cells,migration of neutrophils,and immunological and other relevant functionalities. Meanwhile,they may also be involved in free radical-related apoptosis,inflammation,and activation pathways. Conclusions A total of 251 differentially expressed genes are found to be able to distinguish simple HIV infection from HIV/TB infection. Protein-protein interaction network of top 40 differential expression genes includes RPLP1 gene,which is possibly associated with HIV/TB co-infection and may be involved in and the positive regulation of external stimuli,signal transduction pathways in cells,migration of neutrophils,and immunological functions. These findings may provide certain evidence for the diagnosis and treatment of HIV/TB infection.

Abstract 3306: Aberrant expression of ribosomal protein p1 and its pseudogene in breast tumors

Abstract Introduction: Ribosome biogenesis and translation control are essential cellular processes in growing cancer cells. Defects in ribosomal components can alter the pattern of gene expression, cell cycle progression and cell growth. Human ribosomes consist of four RNA species and 79 ribosomal proteins with 2090 processed and 16 duplicated pseudogenes. Specifically, 60S Acidic Ribosomal Protein P1 (RPLP1) is expressed in a tissue specific manner with multiple processed pseudogenes. We accidentally identified the expressed pseudogene 4 of RPLP1 (RPLP1P4) and determined genetic and molecular mechanism of RPLP1 and RPLP1P4 expression in breast cancer cells. Methods: Expression levels of RPLP1 and RPLP1P4 were quantified using qRT-PCR with total RNAs isolated from 7 normal tissues and 20 breast tumor tissues of 5 different subtypes. Cell cycle progression was analyzed cytofluorimetrically with the Beckman Coulter Gallios Flow Cytometer. Gene expression profiles were performed using Affymetrix GeneChip Human Genome U133 Plus 2.0 Array and analyzed using Partek Genomic Suite. Somatic copy number alterations (SCNA) of RPLP1/RPLP1P4 were detected with the custom designed TaqMan assays using ABI 7900HT real time PCR system. CopyCaller™ Software was used for the SCNA analysis with RNase P as a reference. Results: Because breast cancer subtypes have distinct origins and molecular characteristics, we compared expression of RPLP1 and RPLP1P4 in 5 subtypes of breast tumors. Although RPLP1/RPLP1P4 is ubiquitously expressed in normal and cancer tissues, their expression levels are significantly increased in the basal-like subtype of breast cancer compared to other subtypes with a 2.23 ± 1.06 fold increase in basal-like subtype compared to non-basal subtypes. Interfering RPLP1 expression with siRNA dramatically decreased cell proliferation up to the level of complete inhibition of cell proliferation. FACS data revealed reduced S phase cells in RPLP1 silencing-cells compared to control, suggesting that RPLP1-mediated regulation of cell proliferation is partly mediated through regulation of cell cycle progression. Analysis of gene expression profiles displayed down-regulation of genes involved in cellular metabolism and DNA replication. When we assessed 44 formalin fixed paraffin embedded breast tissues for SCNA of RPLP1/RPLP1P4, we observed RPLP1 amplifications in 44% of tumor DNAs with no amplification observed in normal tissues. The clear difference between tumors and normal tissues demonstrates frequent RPLP1 amplification events during tumorigenesis, which possibly drives an increase in RPLP1 expression and cell proliferation in cancer. Conclusion: Our data suggest a subtype-specific increased expression of a ribosomal protein and its pseudogene, potentially driven by copy number alterations in breast tumors. Future studies to understand the contributions of ribosomal protein genes and their pseudogenes to human neoplasia are warranted. Citation Format: Yoo J. Han, Olufunmilayo I. Olopade. Aberrant expression of ribosomal protein p1 and its pseudogene in breast tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3306. doi:10.1158/1538-7445.AM2014-3306

Characterization of human melanoma cell lines and melanocytes by proteome analysis

We have analyzed the proteomes of two human melanoma cell lines (A375 and 526), and of the human melanocytes, (FOM 78), by two-dimensional electrophoresis (2D-PAGE) and liquid chromatography – tandem mass spectrometry (LC-MS/MS). Our comparative proteomic analysis revealed that six proteins were over-expressed in both melanoma cell lines as compared to melanocytes: galectin-1, inosine-5'-monophosphate dehydrogenase 2, serine/threonine-protein phosphatase 2A 65 kDa regulatory subunit A alpha isoform, protein DJ-1, cyclophilin A and cofilin-1. We show, for the first time, that only specific isoforms of these molecules are over-expressed in melanoma. Different protein profiles were also found between each individual melanoma cell line and the melanocytes. s-Methyl-5-thioadenosine phosphorylase, ubiquitin and ribosomal protein S27 a precursor, the basic form of protein DJ-1, annexin a1, proliferation associated protein 2g4, isoform alfa-enolase of alfa-enolase, protein disulfide-isomerase precursor, and elongation factor 2 were more strongly expressed in A375 cells compared to melanocytes. In 526 cells, 60s acidic ribosomal protein p1 and calreticulin precursor were more highly expressed than in melanocytes. These molecular differences may help in better understanding melanoma development and its different responsiveness to therapies. The identified proteins could be exploited as biomarkers or therapeutic targets for melanoma.

Nitration of tryptophan in ribosomal proteins is a novel post-translational modification of differentiated and naïve PC12 cells

Neuron growth factor (NGF) signaling in PC12 cell, which is derived from pheochromocytoma of rat adrenal medulla, induces expression of neuronal nitric oxide synthase (nNOS) and nitric oxide (NO) production. Subsequently, NO causes differentiation of PC12 cell to neuronal cell with morphological changes, such as neurite extension. In this study, we showed that 6-nitrotryptophan-containing proteins were produced in PC12 cell (naïve PC12 cell) and/or NGF-induced PC12 cell (differentiated PC12 cell). Western blot analysis of the protein extract of naïve PC12 cell and differentiated PC12 cell using anti 6-nitrotryptophan antibody showed several immunoreactive bands, which were subsequently subjected to trypsin digestion and LC–ESI–MS–MS analysis. The peptides from five ribosomal proteins, namely, 60S ribosomal protein L7 (Trp154), 60S acidic ribosomal protein P1 (Trp43), 40S ribosomal protein S2 (Trp60), 40S ribosomal protein S6 (Trp45), and 40S ribosomal protein S19 (Trp52), were identified as nitrotryptophan residue-containing proteins with significant ion score levels ( p < 0.05). Among these, tryptophan nitration was observed only in differentiated PC12 cell for S19 protein, and only in naïve PC12 cell for L7 protein. Tryptophan nitration of the other ribosomal proteins P1, S2, and S6 was observed in both naive and differentiated PC12 cells. The positive signal of nitrotryptophan-containing proteins in the Western blotting around 16 kDa (Band 1), which includes 40S ribosomal protein S19, was suppressed by treatment with NOS inhibitor, L-NAME. The tryptophan nitration of 40S ribosomal protein was not observed by LC–ESI–MS–MS analysis of this sample. This is the first study to identify several specific sites of nitrated tryptophan on proteins not only in viable culture cells but also in a physiological process: cell differentiation.

Antigen-subtracted 2-DE/MS strategy, a novel proteomic analysis platform

In the present study, we developed a novel proteomic research strategy named antigen-subtracted 2-DE/MS strategy and applied it to comparative proteomic analysis of anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-transformed human bronchial epithelial cell line (16HBE-C) and its parental cell line (16HBE) G0/G1 cells. Following pre-purification by ammonium sulfate precipitation, rabbit antibodies against 16HBE G0/G1 cells were coupled with protein A/G PLUS-agarose under the maximal coupling rate of about 50%. The agarose-antibody complex was then used in immunoprecipitation known as antigen subtraction. When the mass ratio of antibody to the sample was 2.5-3:1, the subtraction rates for 16HBE and 16HBE-C G0/G1 cell proteins were 44 and 34%, respectively. Both subtracted and unsubtracted samples were then subjected to the 2-DE resolution. In 16HBE-subtracted 2-DE maps, 315 protein spots were subtracted and 49 new protein spots were detected, whereas in 16HBE-C-subtracted 2-DE maps, 287 protein spots were subtracted and 33 new protein spots were detected. Taken together, antigen subtraction results in 65 new protein spots being allowed to be detected, therefore, makes it possible to get more information of the samples. Finally, 4 protein spots only detected in 16HBE-C-subtracted 2-DE maps were analyzed by the Q-TOF MS/MS, and successfully identified as U6 snRNA-associated Sm-like protein LSm3, 60S acidic ribosomal protein P1, Peroxiredoxin-6 and 60S acidic ribosomal protein P2. These proteins are involved in carcinogenesis, oxidation stress and protein synthesis. In conclusion, the antigen-subtracted 2-DE/MS strategy could reduce the complexities of protein samples and therefore, improve the resolution for the sample analysis.

Isolation and Characterization of a cDNA Clone Encoding One IgE-Binding Fragment of Penicillium brevicompactum

Background:The abundance of allergenic Penicillium species has been associated with an increased incidence of childhood asthma and pulmonary bleeding. Penicillium brevicompactum has been identified as the most prevalent indoorspecies of this genus. However, detailed studies on the allergens of the ubiquitous Penicillium species are still lacking. For the characterization of allergens of prevalent Penicillium species, molecular cloning of the allergen genes of P. brevicompactum was performed in the present study. Methods:A phage cDNA library of P. brevicompactum was constructed in Uni-ZAP^® XR vector using mRNA isolated from the organism. The cDNA library of P.brevicompactum was screened using pooled atopic sera. Results: Screening of P. brevicompactum cDNA library resulted in one positive clone encoding an estimated molecular weight of 11 kDa polypeptide, rich in acidic residues (>20%), with a pI of 3.87. This clone was designated as Pen b 26 and found to be reactive only against the atopic sera obtained from individuals sensitive to P. brevicompactum. The amino acid sequence analysis of Pen b 26 revealed that it had strong homology to the 60S acidic ribosomal protein P1 family from different eukaryotic sources, predominantly fungal aero-allergens. Other features of Pen b 26 including having high alpha-helical content (>50%), alanine-rich residues (>20%), and a well-conserved C-terminal epitope region fits well into the common properties of 60S acidic ribosomal proteins. Conclusions:The results obtained suggest that the allergenic clone, Pen b 26 is a 60S acidic ribosomal protein P1 of P. brevicompactum and shows strong similarity to other P1 family proteins.

Isolation and characterization of a cDNA clone encoding one IgE-binding fragment of Penicillium brevicompactum

Rationale The abundance of allergenic Penicillium species has been associated with an increased incidence of childhood asthma and pulmonary bleeding. Penicillium brevicompactum has been identified as the most prevalent indoor Penicillium species. However, detailed studies on allergen of the ubiquitous Penicillium species are still lacking. For the characterization of allergens of prevalent Penicillium species, molecular cloning of the allergen genes of P. brevicompactum was performed in the present study. Methods A cDNA library of P. brevicompactum was constructed in Uni-ZAP® XR vector using mRNA isolated from the organism. The cDNA library of P. brevicompactum was screened using pooled atopic sera. Results One positive clone encoding a polypeptide of 11.06 kDa, designated as Pb2 was isolated. This clone was found to be reactive only against the atopic sera. The mRNA sequence of the clone was deduced from the cDNA of 0.5 kb transcript and found to be a 321 nt encoding 107 amino acids. Analysis of the crude extracts of the phage clone by SDS-PAGE immunoblot confirmed its expected molecular size. BLAST analysis showed that clone Pb2 had strong homology to the 60S acidic ribosomal protein P1 family from different eukaryotic sources, including the Alt a 12 allergen of mould Alternaria alternata which is an important source of fungal aeroallergens. Conclusions The results obtained suggest that 60S acidic ribosomal protein P1 is an allergen of P. brevicompactum and clone Pb2 contains the cDNA of this allergen.