Progress in EIF5A2 gene in malignant tumors / 肿瘤

Eukaryotic translation initiation factor 5A2 (EIF5A2) is a small universally conserved acidic protein classified in the EIF family. It has been found that EIF5A2 is widely over-expressed in various carcinomas, such as lung cancer, breast cancer and cervical cancer. EIF5A2 mainly promotes the occurrence and development of carcinoma by inducing epithelial-mesenchymal transition. A combination therapy with N1-guanyl-1, 7-diaminohep-tane (GC7), ciclopirox (CPX) and cytokines pharmacological agents can inhibit the activity of EIF5A2 through interfering the process of hypusine post-translational modification, and it is expected to be a good choice for clinical medication. Studies have shown that EIF5A2, as a carcinogenic gene, may be an effective molecular biomarker in the diagnosis and treatment of cancer. This review summarizes the progress in EIF5A2 in carcinoma.

Effect of mild hypothermia on expression of phosphorylated eukaryotic translation initiation factor 2α in hippocampus in a mouse model of cerebral ischemia-reperfusion / 中华麻醉学杂志

Objective To evaluate the effect of mild hypothermia on the expression of phosphorylated eukaryotic translation initiation factor 2α (p-eIf2αt) in the hippocampus in a mouse model of cerebral ischemia-reperfusion (I/R).Methods Sixty pathogen-free healthy male C57BL6 mice,aged 8-12 weeks,weighing 20-30 g,were divided into 3 groups (n =20 each) using a random number table:sham operation group (group S),group I/R and mild hypothermia group (group H).Cerebral I/R was induced by 15-min occlusion of bilateral common carotid arteries followed by reperfusion in chloral hydrate-anesthetized mice.Surface cooling was started immediately after reperfusion to maintain the rectal temperature at 32-34 ℃ for 3 h in group H.The neurologic deficit score was evaluated at 24 h of reperfusion.The mice were then sacrificed,brains were immediately removed,and hippocampi were isolated for examination of pathologic changes of hippocampal CA1 region and for determination of neuroapoptosis (by TUNEL) and expression of peIf2α (by Western blot).The apoptosis rate was calculated.Results Compared with group S,the neurologic deficit scores at 24 h of reperfusion and apoptosis rate of hippocampal neurons were significantly increased,and the expression of p-eIf2α was up-regulated in I/R and H groups (P＜0.05).Compared with group I/R,the neurologic deficit scores at 24 h of reperfusion and apoptosis rate of hippocampal neurons were significantly decreased,and the expression of p-eIf2α was down-regulated in group H (P＜ 0.05).Conclusion Mild hypothermia reduces endoplasmic reticulum stress and inhibits neuroapoptosis through inhibiting the expression of p-eIf2α in the hippocampus in a mouse model of cerebral I/R.

Progress of the relationship between eukaryotic initiation factor 5A and human diseases / 国际外科学杂志

Eukaryotic initiation factor 5A (eIF5A),which is ubiquitous in the eukaryote,is the unique protein containing the special lysine hypusine.There are evidences show that eIFSA is involved in the progress of translation,peptide elongation and peptide bond formation,and takes part in the occurrence and development of various human diseases.The activation of eIF5A is essential to its biological function.The active eIFSA is involved in the growth of plasmodium and contributes to tumor proliferation.And it can act as nuclear output protein to integrate special mRNA,and in this way the special mRNA can shuttle between the nucleus and cytoplasm.Basing on these findings,the scientists pay more attention to eIF5A,and deem it as a direction to cure some related human diseases.

Hypoxia and angiogenesis: regulation of hypoxia-inducible factors via novel binding factors

The mechanisms that regulate angiogenesis in hypoxia or hypoxic microenvironment are modulated by several pro- and antiangiogenic factors. Hypoxia-inducible factors (HIFs) have been established as the basic and major inducers of angiogenesis, but understanding the role of interacting proteins is becoming increasingly important to elucidate the angiogenic processes of a hypoxic response. In particular, with regard to wound healing and the novel therapies for vascular disorders such as ischemic brain and heart attack, it is essential to gain insights in the formation and regulation of HIF transcriptional machineries related to angiogenesis. Further, identification of alternative ways of inhibiting tumor growth by disrupting the growth-triggering mechanisms of increasing vascular supply via angiogenesis depends on the knowledge of how tumor cells develop their own vasculature. Here, we review our findings on the interactions of basic HIFs, HIF-1alpha and HIF-2alpha, with their regulatory binding proteins, histone deacetylase 7 (HDAC7) and translation initiation factor 6 (Int6), respectively. The present results and discussion revealed new regulatory interactions of HIF-related mechanisms.

Deoxyhypusine synthase is phosphorylated by protein kinase C in vivo as well as in vitro

Deoxyhypusine synthase catalyzes the first step in the posttranslational synthesis of an unusual amino acid, hypusine, in the eukaryotic translation initiation factor 5A (eIF-5A) precursor protein. We earlier observed that yeast recombinant deoxyhypusine synthase was phosphorylated by protein kinase C (PKC) in vitro (Kang and Chung, 1999) and the phosphorylation rate was synergistically increased to a 3.5-fold following treatment with phosphatidylserine (P.Ser)/diacylglycerol (DAG)/ Ca2+, suggesting a possible involvement of PKC. We have extended study on the phosphorylation of deoxyhypusine synthase in vivo in different cell lines in order to define its role on the regulation of eIF5A in the cell. Deoxyhypusine synthase was found to be phosphorylated by endogenous kinases in CHO, NIH3T3, and chicken embryonic cells. The highest degree of phosphorylation was found in CHO cells. Moreover, phosphorylation of deoxyhypusine synthase in intact CHO cells was revealed and the expression of phosphorylated deoxyhypusine synthase was significantly diminished by diacyl ethylene glycol (DAEG), a PKC inhibitor, and enhanced by phorbol 12-myristate 13-acetate (PMA) or Ca2+/DAG. Endogenous PKC in CHO cell and cell lysate was able to phosphorylate deoxyhypusine synthase and this modification is enhanced by PMA or Ca2+ plus DAG. Close association of PKC with deoxyhypusine synthase in the CHO cells was evident in the immune coprecipitation and was PMA-, and Ca2+/phospholipiddependent. These results suggest that phosphorylation of deoxyhypusine synthase was PKC-dependent cellular event and open a path for possible regulation in the interaction with eIF5A precursor for hypusine synthesis.