Comparative transcriptomics analysis of Zygosaccharomyces mellis under high-glucose stress

The high-glucose tolerance of yeast is the main factor determining the efficiency of high-density alcohol fermentation.Zygosaccharomyces mellis LGL-1 isolated from honey could survive under 700 g/L high-glucose stress and its tolerant characteristics were identified in our previous study.This study was performed to explore and clarify the high-glucose tolerance mechanism of Z.mellis LGL-1.Comparative transcriptomic analysis was used to analyze the genes with differential expression in Z.mellis under high-glucose conditions of 300,500 and 700 g/L.With 300 g/L samples as reference,there were 937 and 2380 differentially expressed genes(DEGs)in the 500 and 700 g/L samples,respectively.Meanwhile,there was 825 significant DEGs in the 700 g/L samples compared with that of the 500 g/L samples.The result revealed that transcriptional changes in multiple metabolic pathways occur in response to high-glucose stress.q-RT PCR analysis further confirmed that several stress response pathways,such as the high osmolarity glycerol mitogen-activated protein kinase(HOG-MAPK)signal transduction pathway,trehalose synthesis pathway and oxidative stress response are closely related to high-glucose tolerance in Z.mellis.This study clarifies mechanisms of Z.mellis in response to high-glucose osmotic stress,providing theoretical basis for the process control of high-density alcohol fermentation.

Regulation role of miR-204 on SIRT1/VEGF in metabolic memory induced by high glucose in human retinal pigment epithelial cells

AIM:To examine the regulatory role of microRNA-204(miR-204)on silent information regulator 1(SIRT1)and vascular endothelial growth factor(VEGF)under highglucose-induced metabolic memory in human retinal pigment epithelial(hRPE)cells.METHODS:Cells were cultured with either normal(5 mmol/L)or high D-glucose(25 mmol/L)concentrations for 8d to establish control and high-glucose groups,respectively.To induce metabolic memory,cells were cultured with 25 mmol/L D-glucose for 4d followed by culture with 5 mmol/L D-glucose for 4d.In addition,exposed in 25 mmol/L D-glucose for 4d and then transfected with 100 nmol/L miR-204 control,miR-204 inhibitor or miR-204 mimic in 5 mmol/L D-glucose for 4d.Quantitative reverse transcription-polymerase chain reaction(RT-qPCR)was used to detect miR-204 mRNA levels.SIRT1 and VEGF protein levels were assessed by immunohistochemical and Western blot.Flow cytometry was used to investigate apoptosis rate.RESULTS:It was found that high glucose promoted miR-204 and VEGF expression,and inhibited SIRT1 activity,even after the return to normal glucose culture conditions.Upregulation of miR-204 promoted apoptosis inhibiting SIRT1 and increasing VEGF expression.However,downregulation of miR-204 produced the opposite effects.CONCLUSION:The study identifies that miR-204 is the upstream target of SIRT1and VEGF,and that miR-204 can protect hRPE cells from the damage caused by metabolic memory through increasing SIRT1 and inhibiting VEGF expression.