| Background and objectiveTo investigate the change of mitophagy level of bone marrow nucleated red blood cells in anemia patients who dignosed myelodysplastic syndromes(MDS),to explore its significance associated with mitochondrial dysfunction in the anemic pathogenesis of MDS.Materials and methodsFifty-four anemia patients with MDS newly diagnosed in Tianjin Medical University General Hospital and thirty-three non-MDS cases without anemia(immune thrombocytopenia 24 cases,idiopathic granulocytopenia 9 cases)were enrolled in this study.The mitophagy was observed by transmission electron microscopy(TEM).The level of mitophagy receptor NIX,autophagy-associated protein microtubule associated protein 1 light chain 3B(LC3B),the number of mitochondria,the level of mitochondrial membrane potential and the level of ROS in Glyco A + nucleated red blood cells were measured by Flow cytometry.The expression of mitophagy receptor NIX,autophagy promotor gene-AMPK,ULK1,autophagy suppressor gene-m TOR m RNA of Glyco A + nucleated red blood cells were measured by real time PCR.The expression of the mitochondrial outer membrane protein TOM20 in Glyco A + nucleated red blood cells was detected by Western blotting.Results 1.The mitophagy in Glyco A+ NRBC reduced in high-risk MDS patients(1)Autophagosome or autolysosome including mitochondria were scarcely observed by TEM in high-risk MDS.(2)The expression of NIX in Glyco A + nucleated red blood cells in high-risk MDS patients(0.61±0.24)was significantly lower than that in controls(0.79±0.16,P<0.05)and that in low-risk MDS patients(0.81±0.15,P<0.01),there were no significant difference in between the controls and low-risk group(P>0.05).(3)The expression of LC3 B in Glyco A + nucleated red blood cells in high-risk MDS patients(0.22±0.12)was significantly lower than that in controls(0.43±0.22,P<0.001)and that in low-risk MDS patients(0.40±0.16,P=0.001),there were no significant difference in between the controls and low-risk group(P>0.05).2.The m RNA expression of mitophagy receptor NIX,autophagy promotor geneAMPK,ULK1,autophagy suppressor gene-m TOR were measured by Q-PCR(1)The expression of mitophagy receptor NIX m RNA in Glyco A+ nucleated red blood cells in high-risk MDS patients(0.36±0.09)was significantly lower than that in controls(1.44±0.41,P<0.05),there were no significant difference in between the controls and low-risk group(P>0.05),there were no significant difference in between the high-risk MDS patients and and low-risk group(P>0.05).(2)The expression of ULK1 m RNA in Glyco A + nucleated red blood cells in high-risk MDS patients(0.64±0.91)were significantly lower than that in controls(2.70±3.27,P<0.05)and that in low-risk MDS patients(4.98±4.76,P<0.01),there were no significant difference in between the controls and low-risk group(P>0.05);(3)The expression of AMPK m RNA in Glyco A + nucleated red blood cells in high-risk MDS patients(0.53±0.61)were significantly lower than that in controls(1.51±1.25,P<0.05)and that in low-risk MDS patients(1.55±1.70,P<0.05),there were no significant difference in between the controls and low-risk group(P>0.05);(4)The level of m TOR m RNA in Glyco A + nucleated red blood cells in high-risk MDS patients(2.81±2.80)was significantly higher than that in controls(1.29±0.81,P<0.01)and that in low-risk MDS patients(0.85±0.74,P<0.01),there were no significant difference in between the controls and low-risk group(P>0.05).3.The mitochondrial dysfunction in Glyco A+ NRBC measured in high-risk MDS patients(1)The number of mitochondria in Glyco A + nucleated red blood cells in high-risk MDS patients(937.17±707.85)was significantly higher than that in controls(513.49±372.33,P<0.05)and that in low-risk MDS patients(461.74±438.02,P<0.05),there were no significant difference in between the controls and low-risk group(P>0.05).(2)The level of mitochondrial membrane potential in Glyco A + nucleated red blood cells in high-risk MDS patients(0.33±0.18)was significantly lower than that in controls(0.61±0.32,P=0.001)and that in low-risk MDS patients(0.61±0.34,P<0.01),there were no significant difference in between the controls and low-risk group(P>0.05).(3)The level of ROS in Glyco A + nucleated red blood cells in high-risk MDS patients(438.65±322.83)was significantly higher than that in controls(242.77±136.87,P<0.05),and higher than that in low-risk MDS patients(197.40+95.07,P<0.01),there were no significant difference in between the controls and low-risk group(P>0.05).(4)The expression of mitochondrial outer membrane protein TOM20 in high-risk MDS patients(9.42±4.42)was high.4.The correlation analysis with altered mitochondria function and clinic characters in MDS patients(1)The number of mitochondria in Glyco A + nucleated red blood cells was positively correlated with the percentage of ringed sideroblasts(r=0.457,P<0.05)in MDS patients.(2)The level of LC3 B in Glyco A + nucleated red blood cells was positively correlated with the concentration of hemoglobin(r=0.529,P<0.01)in high-risk MDS patients,but was not in low-risk MDS patients(P>0.05).(3)The number of mitochondria in Glyco A + nucleated red blood cells was negatively correlated with the concentration of hemoglobin(r=-0.521,P<0.01)in high-risk MDS patients,but was not in low-risk MDS patients(P>0.05).(4)The level of ROS in Glyco A+ nucleated red blood cells was negatively correlated with mitochondrial membrane potential in high risk MDS patients(r=-0.4612,P<0.05),but was not in low-risk MDS patients(P>0.05).Conclusions: Nix mediated mitophagy is impaired in erythroid cells of MDS,which lead to increase damaged mitochondria and ROS,then DNA damage,and shortening the life of nucleated red blood cells.It may be an effective method to induce mitophagy to correct anemia in MDS. |
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