Li Huihui, Wang Xiaoting, Zhang Yu, Yang Yuan, Zhang Joe Z, Zhou Bing
Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, China (H.L., Y.Z.).
College of Chemistry and Life Science, Beijing University of Technology, China (X.W.).
Circ Res. 2025 Aug 29;137(6):e144-e156. doi: 10.1161/CIRCRESAHA.125.326201. Epub 2025 Jul 29.
Iron is a necessary trace element for multiple reactions but is toxic in excess. Its intracellular balance is delicately maintained. We previously found that the loss of SLC39A13 (solute carrier family 39 member 13)/ZIP13 (zinc-iron permease 13), a newly identified endoplasmic reticulum/Golgi-resident iron transporter, impacted iron homeostasis in multiple tissues. The purpose of this study is to investigate the role of ZIP13 in regulating cardiac functions and the precise mechanism of cardiac injury caused by ZIP13 deficiency.
Cardio-specific knockout of (), tamoxifen-inducible knockout (), and systemic (germline) knockout mouse model were used to study the effect of deletion on cardiac functions. These mice were analyzed for growth, cardiac systolic function, mitochondrial morphology, mitochondrial iron metabolism, and mitochondrial biogenesis and activity. We also generated cardio-specific ferroportin 1 () and () double-knockout mice to compare with mice. Mouse embryonic fibroblasts and primary cardiomyocytes were used for in vitro experiments.
mice displayed severe cardiac systolic dysfunctions. The mitochondrial function and morphology were markedly abnormal in cardiomyocytes, accompanied by cytosolic iron increase and mitochondrial iron decrease. These were also confirmed in vitro with mouse embryonic fibroblasts and primary cardiomyocytes. Moreover, iron supplementation or overexpressing MFRN1 (mitoferrin 1), a mitochondrial iron importer, could substantially restore the mitochondrial iron homeostasis and function of ZIP13-deficient primary cardiomyocytes, indicating mitochondrial iron dyshomeostasis underlies the observed cardiac abnormality. The did not wholly resemble that of , which was associated with elevated cytosolic iron, but no statistically significant change was observed in mitochondrial iron. mice presented a more severe heart defect than either single mutant alone, likely due to a further aggravated iron accumulation in the cytosol of cardiomyocytes.
We propose that ZIP13 and FPN1 are both required to maintain cardiac functions via overlapping but different manners; FPN1 maintains the cytosolic iron by exporting iron out of the cells, while ZIP13 helps balance the iron equilibrium between the cytosol and the organellar network system, including the mitochondrion. These findings establish the critical role of ZIP13 in maintaining mitochondrial iron homeostasis and activity, enabling cardiomyocytes to perform effectively their essential roles.
铁是多种反应所必需的微量元素，但过量时具有毒性。其细胞内平衡得以精细维持。我们之前发现，溶质载体家族39成员13（SLC39A13）/锌铁通透酶13（ZIP13）这一最新鉴定出的内质网/高尔基体驻留铁转运蛋白的缺失，影响了多个组织中的铁稳态。本研究的目的是探究ZIP13在调节心脏功能中的作用以及ZIP13缺乏导致心脏损伤的精确机制。
使用心脏特异性敲除ZIP13的小鼠、他莫昔芬诱导型ZIP13敲除小鼠以及全身性（种系）ZIP13敲除小鼠模型来研究ZIP13缺失对心脏功能的影响。对这些小鼠进行生长、心脏收缩功能、线粒体形态、线粒体铁代谢以及线粒体生物发生和活性方面的分析。我们还构建了心脏特异性铁转运蛋白1（FPN1）和ZIP13双敲除小鼠以与ZIP13敲除小鼠进行比较。使用小鼠胚胎成纤维细胞和原代心肌细胞进行体外实验。
ZIP13敲除小鼠表现出严重的心脏收缩功能障碍。ZIP13敲除心肌细胞中的线粒体功能和形态明显异常，伴有胞质铁增加和线粒体铁减少。在小鼠胚胎成纤维细胞和原代心肌细胞的体外实验中也证实了这些情况。此外，补充铁或过表达线粒体铁输入蛋白线粒体铁转运蛋白1（MFRN1）可显著恢复ZIP13缺乏的原代心肌细胞的线粒体铁稳态和功能，表明线粒体铁稳态失衡是所观察到的心脏异常的基础。ZIP13敲除小鼠的情况与FPN1敲除小鼠并不完全相似，FPN1敲除小鼠与胞质铁升高相关，但线粒体铁未观察到统计学上的显著变化。ZIP13和FPN1双敲除小鼠比单独的任何一种单突变体都表现出更严重的心脏缺陷，可能是由于心肌细胞胞质中铁积累进一步加剧。
我们提出，ZIP13和FPN1都需要通过重叠但不同的方式来维持心脏功能；FPN1通过将铁输出细胞来维持胞质铁水平，而ZIP13有助于平衡胞质与包括线粒体在内的细胞器网络系统之间的铁平衡。这些发现确立了ZIP13在维持线粒体铁稳态和活性方面的关键作用，使心肌细胞能够有效地发挥其基本功能。
