Function and Mechanism of Eukaryotic Translation Initiation Factor 5A in Protein Synthesis / 中国生物化学与分子生物学报

In addition to the ribosome, aminoacyl-tRNA, and mRNA, translation factors are also necessary for protein synthesis.The eukaryotic translation initiation factor 5 A (eIF5A) is essential for cell viability and well conserved in all three domains during evolution.It is the only protein in eukaryotic cells that contains the unusual amino acid hypusine and the unique post-translational modification of eIF5A is strictly required for its function.eIF5A was identified in 1978 for the first time and was thought to stimulate the formation of the first peptide bond during translation initiation phase.Its involvement in the translation of polyproline-containing protein was not uncovered until 2013.With the research of over 40 years, our understanding of eIF5A function has changed dramatically.Recent ribosome profile data demonstrate that eIF5A works more generally at many ribosome stalled sites, and not limited to polyproline motif.It also enhances translation termination by facilitating peptide release.Moreover, eIF5A also indirectly regulates various cell life activities by controlling the translation of certain proteins.In this review, we provide a summary of the post-translational modification, the regulating effects during protein synthesis and autophagy as well as the relationship between eIF5A and human diseases, and explore the evolutionary conservation of eIF5A by comparing with the bacterial and arehaeal orthologs, so as to provide a theoretical basis for the research in related fields.

Mir-595 is a significant indicator of poor patient prognosis in epithelial ovarian cancer.

OBJECTIVE: MiR-595 has been demonstrated to be involved in tumorigenesis of several cancers. However, the clinical significance of miR-595 in epithelial ovarian cancer (EOC) remains unclear. The aim of this study was to explore the correlation of miR-595 expression with clinicopathologic features and prognosis in EOC patients. PATIENTS AND METHODS: Quantitative Real-time PCR (qRT-PCR) was performed to evaluate the expression level of miR-595 in all participants. Correlations between miR-595 levels and clinicopathological factors were investigated. Association of miR-595 expression with overall survival was estimated by the Kaplan-Meier method. Univariate and multivariate Cox regression analyses were performed. RESULTS: We observed that miR-595 was downregulated in EOC tissues in comparison with noncancerous ovarian tissues (p < 0.05). In addition, low miR-595 expression level was significantly associated with advanced FIGO stage (p = 0.003), distant metastasis (p = 0.002), and grade (p = 0.014). Furthermore, significantly shorter overall survival was observed in patients with lower expression of the miR-595. At last, multivariate analysis revealed that decreased expression of miR-595 was an independent predictor of overall survival of EOC patients. CONCLUSIONS: Our data indicated that miR-595 expression might be a novel potential prognostic biomarker for EOC.

Resveratrate protects human skin from damage due to repetitive ultraviolet irradiation.

BACKGROUND: Ultraviolet (UV) exposure results in the production reactive oxygen species. Resveratrol has attracted considerable attentions owing to its natural abundance and multiple biological effects. OBJECTIVE: To investigate the protective effects of resveratrate against damage to human skin induced by repetitive solar simulator ultraviolet radiation (ssUVR). MATERIALS AND METHODS: Fifteen healthy volunteers were enrolled, and six sites on the non-exposed dorsal skin of each volunteer were marked for study. Sites 1-4 were exposed to ssUVR at a dosage of 1.5 minimal erythema dose for consecutive 4 days. Immediately after each exposure, one test material (resveratrate + antioxidant, antioxidant, resveratrate, vehicle) was applied to one of the four sites. Site 5 and site 6 were marked as positive control site (UVR only) and baseline control site (no treatment, no UVR). L*a*b values were assessed preprocedure and postprocedure. Skin biopsies were taken 24 h after the last irradiation. The specimens were stained to determine the number of sunburn cells and melanin content melanin. RESULTS: On resveratrate treated sites, erythema was barely seen with only slight decrease of L value and insignificant increase of *a value. Furthermore, resveratrate significantly inhibited sunburn cell formation, and decreased Fontana-Masson staining in skin samples. CONCLUSIONS: Resveratrate exerts protective effects against repetitive ssUVR-induced sunburn and suntan.

Three dimensionality and orbital characters of the Fermi surface in (Tl,Rb)(y)Fe(2-x)Se2.

We report a comprehensive angle-resolved photoemission spectroscopy study of the tridimensional electronic bands in the recently discovered Fe selenide superconductor ((Tl,Rb)(y)Fe(2-x)Se2 (T(c)=32 K). We determined the orbital characters and the k(z) dependence of the low energy electronic structure by tuning the polarization and the energy of the incident photons. We observed a small 3D electron Fermi surface pocket near the Brillouin zone center and a 2D like electron Fermi surface pocket near the zone boundary. The photon energy dependence, the polarization analysis and the local-density approximation calculations suggest a significant contribution from the Se 4p(z) and Fe 3d(xy) orbitals to the small electron pocket. We argue that the emergence of Se 4p(z) states might be the cause of the different magnetic properties between Fe chalcogenides and Fe pnictides.

Expression and role of Oct3/4, Nanog and Sox2 in regeneration of rat tracheal epithelium.

OBJECTIVES: To explore the role of Oct3/4, Nanog and Sox2 in regeneration of rat tracheal epithelium. MATERIALS AND METHODS: An ex vivo model of rat tracheal epithelial regeneration using 5-fluorouracil (5-FU) was developed, to induce injury. Expression levels of Oct3/4, Nanog and Sox2 were examined using Western blot analysis, RT-PCR or microscopically observed immunofluorescence, and cell morphological changes were observed using HE staining, during the recovery process. RESULTS: Oct3/4, Nanog and Sox2 were not detectable in normal tracheal epithelium. After treatment with 5-FU, the normally proliferating tracheal epithelium desquamated and only a few cells in G0 phase of the cell cycle were left on the basement membrane and Oct3/4, Nanog and Sox2 could be observed at this time. Thereafter, the number of Oct3/4-, Nanog- and Sox2-positive cells increased gradually. When the cells differentiated into ciliate cells, mucous cells or basal cells, and restored pseudostratified mucociliary epithelium, the number of Oct3/4-, Nanog- and Sox2-positive cells decreased and gradually disappeared. CONCLUSIONS: G0 phase cells with resistance to 5-FU damage expressed Oct3/4, Nanog and Sox2. This indicated that these cells were undifferentiated, but had the ability to terminally differentiate into downstream-type cells. They possessed stem cell properties. The results are consistent with Oct3/4, Nanog and Sox2-expressing cells being considered as tracheal stem cells.