A lysosomal protein shields cells from iron-driven death

Ferroptosis is a form of programmed cell death in which free iron drives oxidative damage to the fats in the cell membrane, ultimately destroying the cell. It has attracted growing attention in both ageing research and cancer biology. How cells normally keep this process in check is not fully understood.

Researchers publishing in eLife describe a protein called NINJ2, which sits in the membrane of lysosomes (the cell’s recycling compartments) and interacts with LAMP1, an anchor protein that monitors lysosomal integrity. The study shows that cells lacking NINJ2 are more vulnerable to ferroptosis: the lysosomal membrane becomes leaky, free iron flows into the cell, and production of ferritin, the protein that safely stores iron, declines.

Iron storage and lysosomal stability: a connected system

The findings link two processes that were previously studied in isolation: lysosomal membrane stability and iron homeostasis (the cell’s ability to maintain a safe iron balance). NINJ2 appears to influence both. In its absence, ferritin is more rapidly degraded inside the lysosomes themselves. This degradation is partially reversed when LAMP1 is also knocked down, confirming that the two proteins work together.

The researchers note that both NINJ2 and ferritin are overexpressed in certain iron-dependent cancers, making NINJ2 a candidate therapeutic target. Whether this mechanism is equally relevant to ageing processes outside of cancer biology cannot be determined from this study alone. These are cell biology findings, not clinical results.

Broader relevance for cell survival and ageing

Ferroptosis is relevant beyond cancer. Neurodegeneration, cardiac injury following oxygen deprivation, and immune cell ageing all involve processes in which iron-mediated cell death may play a role. This research provides a new molecular mechanism to help explain how cells protect themselves, and what happens when that protection fails.

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