Copper ion accumulation leads to "cuproptosis," cold-induced cell death

A research team including Professor Atsushi Kuhara, Graduate Student Serina Yamashiro, and Specially Appointed Associate Professor Akane Ohta (at the time of research) of the Graduate School of Natural Science at Konan University, has clarified through the analysis of C. elegans that "cuproptosis," a form of cell death induced by copper ions, is involved in the cold-induced death of animals. This achievement is expected to lead to the development of low-temperature preservation technologies for cells and organs. The results were published in the online early access edition of Nature Communications on May 27.

Cuproptosis is a form of cell death induced by the excessive accumulation of copper ions inside cells, which was discovered in 2022. It is thought that cell death occurs by triggering metabolic abnormalities within mitochondria.

In Japan, the number of deaths due to cold temperatures has continued to exceed those from heatstroke in several recent years. On the other hand, the mechanism by which low temperatures lead to the death of cells and organisms has not been well understood. Therefore, the research group utilized C. elegans to isolate mutants exhibiting abnormalities in cold tolerance, selecting individuals whose survival rate decreased under low-temperature conditions.

When performing genetic analysis on the isolated mutants, they identified the causative gene to be a homolog of mammalian SLC46A3 and named it slcr-46.1. It was also confirmed that in this gene-deficient mutant, the survival rate decreased significantly under low temperatures and that this cold tolerance was restored by introducing the wild-type version of the gene.

From an analysis expressing the gene in specific tissues of the mutant, they confirmed that this cold tolerance abnormality was restored by introducing the gene into the pharyngeal muscle. This revealed that the expression of this gene in the pharyngeal muscle is essential for cold tolerance. Furthermore, introducing the mammalian homolog into the mutant restored cold tolerance, demonstrating that the gene possesses the same function in mammals as well.

It had previously been reported that the mouse homolog is involved in copper ion transport, and its deficiency disrupts copper homeostasis, leading to abnormal copper accumulation in mitochondria. Therefore, the group investigated the possibility that copper ions accumulate abnormally in the mutant compared to the wild type.

Using a probe that fluoresces in response to copper ions to observe copper ions inside the body of C. elegans, strong copper ion accumulation was confirmed in the pharyngeal muscle of the mutant strain compared to the wild-type strain. Particularly in the mutant strains that died after cold exposure, copper ions accumulated remarkably in the posterior region of the pharyngeal muscle, indicating that this abnormal accumulation is involved in the cold-induced death of the mutant.

To investigate the intracellular role of this gene in detail, they introduced the gene into cultured cells derived from Drosophila and examined its intracellular localization, confirming its localization to the lysosomal membrane. Copper ions were also localized within lysosomes, demonstrating that the gene shares a common function with its mammalian counterpart.

When the functions of cuproptosis-related genes were suppressed in the mutant, the survival rate under low temperatures recovered. The same operation improved cold tolerance in the wild-type strain as well. Additionally, when the intracellular copper concentration of the mutant was reduced using a copper chelating agent, the cold tolerance abnormality was restored. This indicated the possibility that copper accumulation is a factor in the cold-induced death of the mutant.

In addition, in mutants exposed to low temperatures, abnormal accumulation of mitochondria was observed in the pharyngeal muscles. It has been suggested that in the C. elegans that dies from cold exposure, normal mitochondrial metabolic function may be impaired. Furthermore, it was also confirmed that when mammalian cells were cultured under lower temperature conditions than usual, the expression levels of cuproptosis-related genes increased.

It is known that copper accumulates in some cancer cells, and this could also lead to the development of new cancer therapies.

Kuhara stated: "In this study, we have clarified for the first time in the world that 'cuproptosis,' a new form of cell death induced by copper ions, is involved in the cold-induced death of animals. It was shown that this mechanism may be common from C. elegans to mammalian cells. In addition to understanding cold adaptation mechanisms, applications toward low-temperature preservation technologies for organs for transplantation and the control of cell death are expected."

Journal Information
Publication: Nature Communications
Title: Cuproptosis inducers mediate cold lethality via SLCR-46.1 in C. elegans
DOI: 10.1038/s41467-026-73498-y