Effects of histamine on mRNA expression of Egr-1 in astrocytes / 中国病理生理杂志

AIM:To explore whether histamine can regulate the expression of early growth response factor-1 (Egr-1) in the cerebral cortex astrocytes.METHODS:Normal wild-type (WT) mice, histidine decarboxylase knockout ( HDC-KO) mice and histamine treated HDC-KO mice were sacrificed for extracting the total RNA of the cerebral cortex. Primary cultured rat cortical astrocytes were treated with histamine at concentrations of 10 -8 , 10 -7 , 10 -6 , 10 -5 or 10 -4 mol/L for 15, 30, 60, 120 or 240 min.H1 or H2 receptor antagonists were pretreated for 15 min before histamine treat-ment.After histamine treatment, the cell total RNA or protein was extracted.The expression of Egr-1 at mRNA and protein levels was determined by real-time PCR and Western blot.RESULTS:The mRNA level of Egr-1 in cerebral cortex of HDC-KO mice was significantly lower than that in WT mice, while exogenous histamine induced the mRNA expression of Egr-1 in HDC-KO mice.In cultured astrocytes, histamine induced the mRNA expression of Egr-1.The maximum increase in the mRNA level of Egr-1 was produced by histamine at concentration of 10 -5 mol/L.In addition, histamine-induced Egr-1 mRNA accumulation peaked at 30 min after commencing stimulation, while histamine significantly increased Egr-1 protein expression at 60 min.Furthermore, histamine-induced Egr-1 expression was inhibited by H1 receptor antagonist but not H2 receptor antagonist.CONCLUSION:Histamine up-regulates the Egr-1 expression in cerebral cortex and cultured astrocytes, which may attribute to H1 receptor activation.

Essential regulatory elements for NHE3 gene transcription in renal proximal tubule cells

The objectives of the present study were to identify the cis-elements of the promoter absolutely required for the efficient rat NHE3 gene transcription and to locate positive and negative regulatory elements in the 5’-flanking sequence (5’FS), which might modulate the gene expression in proximal tubules, and to compare this result to those reported for intestinal cell lines. We analyzed the promoter activity of different 5’FS segments of the rat NHE3 gene, in the OKP renal proximal tubule cell line by measuring the activity of the reporter gene luciferase. Because the segment spanning the first 157 bp of 5’FS was the most active it was studied in more detail by sequential deletions, point mutations, and gel shift assays. The essential elements for gene transcription are in the region -85 to -33, where we can identify consensual binding sites for Sp1 and EGR-1, which are relevant to NHE3 gene basal transcription. Although a low level of transcription is still possible when the first 25 bp of the 5’FS are used as promoter, efficient transcription only occurs with 44 bp of 5’FS. There are negative regulatory elements in the segments spanning -1196 to -889 and -467 to -152, and positive enhancers between -889 and -479 bp of 5’FS. Transcription factors in the OKP cell nuclear extract efficiently bound to DNA elements of rat NHE3 promoter as demonstrated by gel shift assays, suggesting a high level of similarity between transcription factors of both species, including Sp1 and EGR-1.

Effects of hypoxic preconditioning on EGR-1 expression of hepatocytes in a rat model undergoing liver autotransplantation / 中华普通外科杂志

Objective To investigate the effect of hypoxic preconditioning on hepatocytes early growth response factor 1 ( EGR-1 ) in a rat liver autotransplantation. Methods The rat portal vein perfusion model was established for donor liver autotransplantation. Rats were then divided into group A:hypoxic preconditioning was done before transplantation; group B: rats undergoing liver transplantation without preconditioning; group C: Normal control group of rats. Liver histopathological changes, the mRNA expression of HIF-1, TNF-1 and the WB results of EGR-1 were compared between groups. Results The expression of HIF-1 α RNA determined in group A was more obvious than in group B and group C. Six hours after surgery, the expression in group A was significantly higher than that in group B (t =9. 601, df= 10, 2-tailed Sig = 0. 000, P<0. 05 ) ; Egr-1 protein expression in group A and group B increased after surgery,with that in group A being significantly lower than that in group B. The RT-PCR expression of TNF-α RNA in group B compared with group A and group C was more obvious. Six hours after operation, the expression of TNF in group B was significantly higher than that in group A ( t = -12. 067, df = 10, 2-tailed Sig =0. 000, P<0. 05 ). The expression of Egr-1 was positively correlated with that of TNF. A liver cell pathology showed less severe injury in structure of hepatic lobule, mild swelling of liver cells, no significant changes in liver tissue. Conclusions Hypoxic preconditioning adaptation in rat liver transplantation generates modest increase in EGR-1, and reduces the production of TNF and other inflammatory factors.