Influence of sodium nitroprusside on expressions of FBXL5 and IRP2 in SH-SY5Y cells / 生理学报

Iron accumulation in the brain is associated with the pathogenesis of Parkinson's disease (PD). Misexpression of some iron transport and storage proteins is related to iron dyshomeostasis. Iron regulatory proteins (IRPs) including IRP1 and IRP2 are cytosolic proteins that play important roles in maintaining cellular iron homeostasis. F-box and leucine-rich repeat protein 5 (FBXL5) is involved in the regulation of iron metabolism by degrading IRP2 through the ubiquitin-proteasome system. Nitric oxide (NO) enhances the binding activity of IRP1, but its effect on IRP2 is ambiguous. Therefore, in the present study, we aim to determine whether sodium nitroprusside (SNP), a NO donor, regulates FBXL5 and IRP2 expression in cultured SH-SY5Y cells. MTT assay revealed that treatment of SNP attenuated the cell viability in a dose-dependent manner. Flow cytometry test showed that 100 and 300 μmol/L SNP administration significantly reduced the mitochondrial membrane potential by 45% and 60%, respectively. Moreover, Western blotting analysis demonstrated that 300 μmol/L SNP significantly increased FBXL5 expression by about 39%, whereas the expression of IRP2 was decreased by 46%, correspondingly. These findings provide evidence that SNP could induce mitochondrial dysfunction, enhance FBXL5 expression and decrease IRP2 expression in SH-SY5Y cells.

Expression of iron regulatory protein-2 and ferritins in intestinal mucosa of rats with iron deficiency / 中国实验血液学杂志

In order to investigate the influence of iron deficiency on the mRNA expression of iron regulatory protein (IRP(2)) mRNA and ferritins (FN) in intestinal mucosa of rat, the animal model of rat with nutritional iron deficiency was established. According to the measurement of serum iron (sI), serum fertitin (sFn) and Hb, the experiments were divided into 4 groups: control group, recessive iron deficiency group, mild iron deficiency group and moderate iron deficiency group. sI was measured by flame assay and sFN was measured by radioimmunoassay, the expressions of irp(2) mRNA and fn mRNA were detected by RT-PCR. The results showed that (1) with aggravation of iron deficiency, the levels of sI and sFN in experimental groups decreased and had significant difference from that in control group, except sI level in the recessive iron deficiency group; (2) with aggravation of iron deficiency, the expression of irp(2) mRNA in duodenum mucosa elevated, and the expressions of irp(2) mRNA in moderate iron deficiency group and mild iron deficiency group were higher than that in control group (p < 0.01), the expression of irp(2) mRNA in moderate iron deficiency group was higher than that in recessive iron deficiency group (p < 0.05), but the expression of irp(2) mRNA did not showed statistical difference between mild iron deficiency group and moderate iron deficiency group (p > 0.05); (3) with aggragation of iron deficiency, the expression of fn mRNA in dudemum mucosa decreased, the expression levels fn mRNA in control and moderate groups were highest and lowest, respectively, there were significant differences between experimental and control groups (p < 0.05), and between experimental groups (p < 0.05); (4) the expression of irp(2) mRNA and fn mRNA in moderate iron difficiency group showed negative correlation (r = 0.662, p < 0.05). It is concluded that IRP(2) protein serves as an important regulator of iron metabolism in the human body, and regulates iron uptake from the intestine by controlling the expression of fn mRNA at the post transcriptional level.

Expression of IRP2 mRNA, TfR mRNA and Fn mRNA in HL-60 cells / 中国实验血液学杂志

To explore the mechanism of iron metabolism and its regulation as well as the roles of IRP(2) in ion metabolism of HL-60 cells, HL-60 cells were cultured in RPMI 1640 medium supplemented with 10% heat-inactivated fetal bovine serum, which was treated with ferric chloride (FeCl(3)) or deferoxamine (DFO). The cells were harvested at 12, 24 and 48 hours of proliferation, and total RNA was isolated; cDNA was synthesized by reverse transcription (RT), and relative expression levels of IRP(2) mRNA, Fn mRNA and TfR mRNA were determined by RT-PCR. The results showed at follows: (1) the level of IRP(2) mRNA remained constant in all cells, whether or not treated with DFO or FeCl(3). However, the expression of IRP(2) mRNA decreased when the time of cell culture was prolonged. There was no significant difference between groups (F(B-S) = 1.199, P > 0.05), but there was significant difference among the different time culture (F(W-S) = 43.418, P < 0.01). (2) Cells which treated neither with DFO nor ferri chloride showed significant difference from the control (F(W-S) = 7.184, F(B-S) = 113.926; P < 0.01). The level of TfR mRNA increased in the cells treated with DFO. Surprisingly, when cells treated with FeCl(3), there was not decline of TfR mRNA expression, but it increased lightly at 12 hours and peaked at 24 hours and declined drastically at 48 hours. (3) The level of Fn mRNA in the cells treated with FeCl(3) was approximately 2-fold as the control cells. In contrast with the control cells, there was significant difference (P < 0.05). The level of Fn mRNA of the cells treated with DFO had little change. As compared with the control cells, no significant difference was seen (P > 0.05). (4) There was not any significant correlation between IRP(2) mRNA and TfR mRNA or Fn mRNA in HL-60 cells (r = -0.005; r = 0.074; P > 0.05). It is concluded that (1) IRP(2) may regulate the iron metabolism in HL-60 cells by altering amounts of the IRP(2) 3.7- or 6.4-kb mRNA at the transcriptional level, or by IRP(2) degradation at the post transcriptional level. (2) Both of Fn mRNA and TfR mRNA participated, more or less, in the iron metabolism in HL-60 cells.