Ferreira Ana, Rivera Alicia, Wohlgemuth Jay G, Dlott Jeffrey S, Snyder L Michael, Alper Seth L, Romero Jose R
Interdisciplinary Centre of Social Sciences (CICS.NOVA), Faculty of Social Sciences and Humanities (NOVA FCSH), Lisbon, Portugal.
Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States.
Front Cell Dev Biol. 2022 Apr 4;10:861644. doi: 10.3389/fcell.2022.861644. eCollection 2022.
Hyperglycemia is associated with decreased Mg content in red blood cells (RBC), but mechanisms remain unclear. We characterized the regulation of Mg efflux by glucose in human RBC. We observed that hemoglobin A (HbA) values correlated with Na-dependent Mg efflux (Na/Mg exchange) and inversely correlated with cellular Mg content. Treatment of cells with 50 mM D-glucose, but not with sorbitol, lowered total cellular Mg (2.2 ± 0.1 to 2.0 ± 0.1 mM, < 0.01) and enhanced Na/Mg exchange activity [0.60 ± 0.09 to 1.12 ± 0.09 mmol/10 cell × h (flux units, FU), < 0.05]. In contrast, incubation with selective Src family kinase inhibitors PP2 or SU6656 reduced glucose-stimulated exchange activation ( < 0.01). Na/Mg exchange activity was also higher in RBC from individuals with type 2 diabetes (T2D, 1.19 ± 0.13 FU) than from non-diabetic individuals (0.58 ± 0.05 FU, < 0.01). Increased Na/Mg exchange activity in RBC from T2D subjects was associated with lower intracellular Mg content. Similarly increased exchange activity was evident in RBC from the diabetic / mouse model as compared to its non-diabetic control ( < 0.03). Extracellular exposure of intact RBC from T2D subjects to recombinant peptidyl-N-glycosidase F (PNGase F) reduced Na/Mg exchange activity from 0.98 ± 0.14 to 0.59 ± 0.13 FU ( < 0.05) and increased baseline intracellular Mg content (1.8 ± 0.1 mM) to normal values (2.1 ± 0.1 mM, < 0.05). These data suggest that the reduced RBC Mg content of T2D RBC reflects enhanced RBC Na/Mg exchange subject to regulation by Src family kinases and by the N-glycosylation state of one or more membrane proteins. The data extend our understanding of dysregulated RBC Mg homeostasis in T2D.
高血糖与红细胞（RBC）中镁含量降低有关，但其机制尚不清楚。我们研究了葡萄糖对人红细胞中镁外流的调节作用。我们观察到血红蛋白A（HbA）值与钠依赖性镁外流（钠/镁交换）相关，与细胞内镁含量呈负相关。用50 mM D-葡萄糖处理细胞，但不用山梨醇处理，可降低细胞总镁含量（从2.2±0.1 mM降至2.0±0.1 mM，P<0.01），并增强钠/镁交换活性[从0.60±0.09 mmol/10细胞×小时（通量单位，FU）增至1.12±0.09 mmol/10细胞×小时，P<0.05]。相比之下，用选择性Src家族激酶抑制剂PP2或SU6656孵育可降低葡萄糖刺激的交换激活（P<0.01）。2型糖尿病（T2D）患者红细胞中的钠/镁交换活性（1.19±0.13 FU）也高于非糖尿病个体（0.58±0.05 FU，P<0.01）。T2D患者红细胞中钠/镁交换活性增加与细胞内镁含量降低有关。同样，与非糖尿病对照相比，糖尿病小鼠模型红细胞中的交换活性也明显增加（P<0.03）。将T2D患者的完整红细胞细胞外暴露于重组肽基-N-糖苷酶F（PNGase F）可使钠/镁交换活性从0.98±0.14 FU降至0.59±0.13 FU（P<0.05），并使基线细胞内镁含量（1.8±0.1 mM）增加至正常水平（2.1±0.1 mM，P<0.05）。这些数据表明，T2D患者红细胞中镁含量降低反映了红细胞钠/镁交换增强，这受Src家族激酶以及一种或多种膜蛋白的N-糖基化状态调节。这些数据扩展了我们对T2D中红细胞镁稳态失调的理解。
