丙酮酸程序化预处理：脯氨酸羟化酶的差异性调控机制.docVIP

  A novel programmed application of pyruvate: differential stabilization of HIF-1a and HIF-2a# 5 10 15 20 25 30 35 40 45 REN Hao, Xiaoyue Zhai* (china medical university, histology and embryology) Abstract: Purpose. To develop a novel hypoxia preconditioning mimicking approach by pyruvate programming in the retina focusing on the interplay between HIFs and prolyl hydroxylases (PHDs). Methods. 6-8 weeks old BALB/c mice was treated with pyruvate in a programmed regime. Western blotting and real time PCR were applied for the protein and mRNA studies. Retinal morphology was checked by toluidine blue staining. TUNEL staining and free nucleosome assay were used to examine apoptosis. Retinal organic culture was developed to investigate the pyruvate mechanism in vitro. Result. As the predominant isomer in the retina, HIF-1a is highly stabilized by pyruvate both in vivo and vitro. This was followed by a concomitant increase of PHD2 level. In contrast, HIF-2a and PHD1 were not affected by pyruvate in vivo. The down-stream genes of hemoxygenase-1 (HO-1) and erythropoietin (EPO) also mirrored the changes of the HIFs respectively. Our data revealed a PHD2-HIF-1a feedback loop, which was blocked by pyruvate and rendered further HIF-1a accumulation. In vitro, HIF-2a was also able to be stabilized by pyruvate inhibition to PHD1, but only happed after oxygen withdrawal. Pyruvate treatment reduced retinal apoptosis not only before but also after the light insult. Conclusion. This novel pyruvate programming was retinal protective not only with preconditioning but also post-conditioning. This protection was mainly due to HIF-1a stabilization but not HIF-2a. This differentiation was due to the specific abundance of PHD isoforms in the retina and importantly their distinct preference to HIFs as degradating enzymes. Key words: histology and embryology; HIF; pyruvate pre-conditioning 0 Introduction The retina is constantly under light exposure, prolonged intensive white light can trig