In the face of the worldwide threat of severe acute respiratory syndrome (SARS) to human life, some of the most urgent challenges are to develop fast and accurate analytical methods for early diagnosis of this disease as well as to create a safe anti-viral vaccine for prevention. To these ends, we investigated the antigenicity of the spike protein (S protein), a major structural protein in the SARS-coronavirus (SARS-CoV). Based upon the theoretical analysis for hydrophobicity of the S protein, 18 peptides were synthesized. Using Enzyme-Linked Immunosorbent Assay (ELISA), these peptides were screened in the sera from SARS patients. According to these results, two fragments of the S gene were amplified by PCR and cloned into pET-32a. Both S fragments were expressed in the BL-21 strain and further purified with an affinity chromatography. These recombinant S fragments were confirmed to have positive cross-reactions with SARS sera, either by Western blot or by ELISA. Our results demonstrated that the potential epitope regions were located at Codons 469-882 in the S protein, and one epitope site was located at Codons 599-620. Identification of antigenic regions in the SARS-CoV S protein may be important for the functional studies of this virus or the development of clinical diagnosis.
Antigens, Viral ; immunology ; Chromatography, High Pressure Liquid ; Cloning, Molecular ; Electrophoresis, Polyacrylamide Gel ; Enzyme-Linked Immunosorbent Assay ; Genetic Vectors ; Humans ; Mass Spectrometry ; Membrane Glycoproteins ; genetics ; immunology ; metabolism ; Molecular Weight ; Peptide Fragments ; chemistry ; Recombinant Proteins ; genetics ; immunology ; SARS Virus ; genetics ; immunology ; metabolism ; Spike Glycoprotein, Coronavirus ; Viral Envelope Proteins ; genetics ; immunology ; metabolism

The abnormality of serine/threonine kinase Aurora-A is seen in many types of cancers. Although in physiological context it has been shown to play a vital role in cellular mitosis, how this oncogene contributes to tumorigenesis remains unclear. Here we demonstrate that Aurora-A overexpression enhances both the expression level and transcriptional activity of c-Myc. The inhibition of c-Myc expression by RNA interference significantly impaired the oncogenic potential of Aurora-A, resulting in attenuated cellular proliferation and transformation rates as well as fewer centrosomal aberrations. Furthermore, downregulation of c-Myc effectively overcame Aurora-A-induced resistance to cisplatin in esophageal cancer cells. Taken together, our results suggest an important role for c-Myc in mediating the oncogenic activity of Aurora-A, which may in turn allow for future targeting of c-Myc as a potential therapeutic strategy for tumors with Aurora-A overexpression.
Cell Line, Transformed ; Cell Proliferation/drug effects ; Cell Transformation, Neoplastic/drug effects/genetics ; Centro ; Chromo ; Cisplatin/pharmacology ; Down-Regulation ; E ; Gene Expression Regulation, Neoplastic/drug effects ; Humans ; Protein-Serine-Threonine Kinases/genetics/*metabolism ; Proto-Oncogene Proteins c-myc/genetics/*metabolism ; RNA, Small Interfering/genetics ; Transcriptional Activation ; Transgenes/genetics

The nucleocapsid protein (N protein) has been found to be an antigenic protein in a number of coronaviruses. Whether the N protein in severe acute respiratory syndrome-associated coronavirus (SARS-CoV) is antigenic remains to be elucidated. Using Western blot and Enzyme-linked Immunosorbent Assay (ELISA), the recombinant N proteins and the synthesized peptides derived from the N protein were screened in sera from SARS patients. All patient sera in this study displayed strong positive immunoreactivities against the recombinant N proteins, whereas normal sera gave negative immunoresponses to these proteins, indicating that the N protein of SARS-CoV is an antigenic protein. Furthermore, the epitope sites in the N protein were determined by competition experiments, in which the recombinant proteins or the synthesized peptides competed against the SARS-CoV proteins to bind to the antibodies raised in SARS sera. One epitope site located at the C-terminus was confirmed as the most antigenic region in this protein. A detailed screening of peptide with ELISA demonstrated that the amino sequence from Codons 371 to 407 was the epitope site at the C-terminus of the N protein. Understanding of the epitope sites could be very significant for developing an effective diagnostic approach to SARS.
Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; Epitopes ; chemistry ; immunology ; Humans ; Nucleocapsid Proteins ; chemistry ; immunology ; Peptide Fragments ; chemical synthesis ; Plasmids ; Recombinant Proteins ; immunology ; isolation & purification ; metabolism ; SARS Virus ; genetics ; immunology ; metabolism

The Coronaviridae family is characterized by a nucleocapsid that is composed of the genome RNA molecule in combination with the nucleoprotein (N protein) within a virion. The most striking physiochemical feature of the N protein of SARS-CoV is that it is a typical basic protein with a high predicted pI and high hydrophilicity, which is consistent with its function of binding to the ribophosphate backbone of the RNA molecule. The predicted high extent of phosphorylation of the N protein on multiple candidate phosphorylation sites demonstrates that it would be related to important functions, such as RNA-binding and localization to the nucleolus of host cells. Subsequent study shows that there is an SR-rich region in the N protein and this region might be involved in the protein-protein interaction. The abundant antigenic sites predicted in the N protein, as well as experimental evidence with synthesized polypeptides, indicate that the N protein is one of the major antigens of the SARS-CoV. Compared with other viral structural proteins, the low variation rate of the N protein with regards to its size suggests its importance to the survival of the virus.
Amino Acid Motifs ; genetics ; Amino Acid Sequence ; Antigens, Viral ; immunology ; Base Composition ; Base Sequence ; Cluster Analysis ; Computational Biology ; DNA Primers ; Enzyme-Linked Immunosorbent Assay ; Genetic Variation ; Molecular Sequence Data ; Nucleocapsid Proteins ; genetics ; immunology ; metabolism ; Phosphorylation ; SARS Virus ; genetics ; Sequence Analysis, DNA

Objective: To investigate the effect of tumor-associated macrophage (TAM) on the anti-tumor function of chidamide and to explore the mechanism. Methods: Mouse macrophage cell linesAna1 and Raw264.7 were cultured in vitro and induced into TAM with tumor supernatant. HDAC enzyme activity was detected after TAM treated with chidamide. The mRNA expressions of cytokines, such as IL-6, IL-12,TNF and IL-1β, in TAM were detected by qPCR. The protein expression of NF-κB and STAT3 in TAM treated with chidamide were detected by Wb. The mixture of TAM and colon cancer CT26 cells was inoculated into nude mice to construct the subcutaneous xenograft model; and the efficacy of chidamide (3.87 mg/kg) on the growth of CT26 xenograft tumors was observed. The protein expressions of PCNA, F4/80, Arg1 and iNos were detected by immunohistochemistry. Results: Chidamide inhibited the proliferation of CT26 cells. In the in vivo experiment, the inhibition rate of chidamide alone on CT26 xenograft was about 18.7%; however, the inhibition rate was up to 57.2% with the presence of TAM. Chidamide could inhibit the activity of HDAC enzyme in TAM, and further increase the Histone acetylation level. Chidamide could affect the expression of nuclear transcription factor NF-κB, inhibit the expressions of Arg1, IL-6 and IL-12, but up-regulate the expressions of iNOS, TNF and IL-1β in TAM. Conclusion: Chidamide can enhance its inhibitory effect on colon cancer CT26 cells via regulating the expression of cytokines and inhibiting the activity of HDAC in TAM.