Abcb10 is a mitochondrial membrane protein involved in hemoglobinization of red cells. Abcb10 topology and ATPase domain localization suggest it exports a substrate, likely biliverdin, out of mitochondria that is necessary for hemoglobinization. In this study, we generated Abcb10 deletion cell lines in both mouse murine erythroleukemia and human erythroid precursor human myelogenous leukemia (K562) cells to better understand the consequences of Abcb10 loss. Loss of Abcb10 resulted in an inability to hemoglobinize upon differentiation in both K562 and mouse murine erythroleukemia cells with reduced heme and intermediate porphyrins and decreased levels of aminolevulinic acid synthase 2 activity. Metabolomic and transcriptional analyses revealed that Abcb10 loss gave rise to decreased cellular arginine levels, increased transcripts for cationic and neutral amino acid transporters with reduced levels of the citrulline to arginine converting enzymes argininosuccinate synthetase and argininosuccinate lyase. The reduced arginine levels in Abcb10-null cells gave rise to decreased proliferative capacity. Arginine supplementation improved both Abcb10-null proliferation and hemoglobinization upon differentiation. Abcb10-null cells showed increased phosphorylation of eukaryotic translation initiation factor 2 subunit alpha, increased expression of nutrient sensing transcription factor ATF4 and downstream targets DNA damage inducible transcript 3 (Chop), ChaC glutathione specific gamma-glutamylcyclotransferase 1 (Chac1), and arginyl-tRNA synthetase 1 (Rars). These results suggest that when the Abcb10 substrate is trapped in the mitochondria, the nutrient sensing machinery is turned on remodeling transcription to block protein synthesis necessary for proliferation and hemoglobin biosynthesis in erythroid models.

Abcb10 是一种参与红细胞血红蛋白化的线粒体膜蛋白。 Abcb10 拓扑结构和 ATP 酶结构域定位表明，它从线粒体中输出血红蛋白化所需的底物（可能是胆绿素）。在这项研究中，我们在小鼠鼠红白血病和人红系前体人髓性白血病 (K562) 细胞中生成了Abcb10缺失细胞系，以更好地了解 Abcb10 缺失的后果。 Abcb10 的缺失导致 K562 和小鼠红白血病细胞在分化时无法血红蛋白化，血红素和中间卟啉减少，氨基乙酰丙酸合酶 2 活性水平降低。代谢组学和转录分析表明，Abcb10 缺失导致细胞精氨酸水平降低，阳离子和中性氨基酸转运蛋白的转录物增加，同时瓜氨酸到精氨酸的转换酶精氨琥珀酸合成酶和精氨琥珀酸裂合酶的水平降低。 Abcb10 缺失细胞中精氨酸水平的降低导致增殖能力下降。精氨酸补充改善了 Abcb10 缺失的增殖和分化时的血红蛋白化。 Abcb10 缺失细胞显示真核翻译起始因子 2 亚基 α 的磷酸化增加，营养感应转录因子 ATF4 和下游靶标 DNA 损伤诱导转录物 3 (Chop)、ChaC 谷胱甘肽特异性 γ-谷氨酰环转移酶 1 (Chac1) 和精氨酰基的表达增加。 tRNA 合成酶 1 (Rars)。 这些结果表明，当 Abcb10 底物被捕获在线粒体中时，营养传感机制就会开启重塑转录，以阻断红细胞模型中增殖和血红蛋白生物合成所需的蛋白质合成。