An international research team has uncovered a mechanism that protects nerve cells from a form of premature cell death known as ferroptosis. Headed by Prof. Marcus Conrad, PhD, director of the Institute of Metabolism and Cell Death at Helmholtz Munich, the scientists’ in vitro experiments and in vivo work in mice link a genetic mutation in the enzyme GPX4 with ferroptotic neurodegeneration and Alzheimer’s-like signatures in mouse models. The team suggests the study provides the first molecular evidence that ferroptosis can drive neurodegeneration in the brain, and could point to new therapeutic strategies for neurodegenerative diseases, particularly for severe early-onset childhood dementia.
“Our data indicate that ferroptosis can be a driving force behind neuronal death—not just a side effect,” said Svenja Lorenz, PhD, one of the first authors of the researchers’ published paper in Cell. “Until now, dementia research has often focused on protein deposits in the brain, so-called amyloid ß plaques. We are now putting more emphasis on the damage to cell membranes that sets this degeneration in motion in the first place.”
In their report, titled “A fin-loop-like structure in GPX4 underlies neuroprotection from ferroptosis,” Lorenz, together with co-senior author Prof. Marcus Conrad, director of the Institute of Metabolism and Cell Death at Helmholtz Munich and chair of Translational Redox Biology at the Technical University of Munich (TUM), concluded, “These insights emphasize the pathogenic nature of ferroptosis in the brain and underscore its promise as a therapeutic target across neurodegenerative diseases.”
The progressive loss of neurons is a recurring feature of different neurodegenerative diseases, but each different condition presents with distinct pathological hallmarks, many of which have been proposed as causal drivers and therapeutic targets, the authors wrote. Genome-wide association studies (GWASs) have identified genetic susceptibilities associated with these diseases, and motivated efforts to match molecular mechanisms with precision therapeutic strategies, they continued. However, “… despite these insights, neuronal loss, the most salient feature, remains insufficiently explained, particularly with respect to the upstream pathways that drive cell death.”
Why do neurons die in dementia—and can this process be slowed down? The newly reported research has identified how neurons protect themselves against ferroptotic cell death. Central to this defense mechanism is glutathione peroxidase 4 (GPX4), “… a selenoenzyme now recognized as the central regulator of ferroptosis, a non-apoptotic, iron-dependent form of cell death implicated in diverse diseases,” the authors stated. “Glutathione peroxidase 4 (GPX4) is the guardian of ferroptosis, although its membrane-protective function remains poorly understood.”
A single mutation—R152H—in the gene that encodes GPX4 can disrupt a crucial, previously unknown component of the enzyme’s function. In affected children, this leads to severe early-onset dementia. “… pathogenic variants in GPX4 have been linked to Sedaghatian-type spondylometaphyseal dysplasia (SSMD), an ultra-rare autosomal recessive disorder characterized by severe neurodegeneration and skeletal abnormalities,” the researchers explained.
When fully functional GPX4 inserts a short protein loop—a kind of “fin”—into the inner side of the neuronal cell membrane, enabling the enzyme to neutralize harmful substances known as lipid peroxides. “GPX4 is a bit like a surfboard,” said Conrad. “With its fin immersed into the cell membrane, it rides along the inner surface and swiftly detoxifies lipid peroxides as it goes.”
The single point mutation found in children with the early-onset dementia alters this fin-like protein loop: the enzyme can no longer insert into the membrane properly to perform its cell-protective function. Lipid peroxides are then free to damage the membrane, triggering ferroptosis and cell rupture, and the neurons die.
The newly reported study began with three children in the United States who suffer from the extremely rare form of early childhood dementia. All three carry the same change in the GPX4 gene, known as the R152H mutation. Several loss-of-function mutations in GPX4 have been reported, the authors noted, but identification of a missense variant, R152H, in three patients from two unrelated families presented an opportunity to investigate ferroptosis-driven disease in humans. “Here, we dissect the structural and functional impact of a homozygous GPX4 missense variant (p.R152H) found in three patients suffering from the ultra-rare autosomal recessive disorder SSMD,” they wrote.
Using cell samples from an affected child, the researchers were able to study the effects of the mutation in more detail and reprogrammed the cells back into a stem-cell-like state. From these reprogrammed stem cells, they then generated cortical neurons and brain organoids, which are three-dimensional tissue structures resembling early brain tissue.
To understand what happens at the whole-organism level, the team then introduced the R152H mutation into a mouse model, specifically altering the GPX4 enzyme in different types of nerve cells. They found that the variant “invariably failed to suppress ferroptosis in vitro or in vivo.” Using high-resolution NMR spectroscopy and X-ray crystallography, the researchers showed that the R152H mutation destabilizes the fin-like loop, which is critical for engaging with lipid membranes. “We find that this collapse impairs GPX4’s ability to interact with lipid bilayers, its quintessential site of action.”
As a result of the impaired GPX4 function, the animals gradually developed severe motoric deficits, with dying neurons in the cerebral cortex and cerebellum, and pronounced neuroinflammatory responses in the brain—a pattern that closely mirrors the observations in the affected children and strongly resembles neurodegenerative disease profiles.
In parallel, the researchers analyzed which proteins change in abundance in the experimental model. They observed a pattern strikingly similar to that seen in patients with Alzheimer’s disease: numerous proteins that are increased or decreased in Alzheimer’s were likewise dysregulated in mice lacking functional GPX4. This suggests that ferroptotic stress may play a role not only in this rare early-onset disorder, but potentially also in more common forms of dementia. “Moreover, we show that Gpx4-null mice exhibit protein expression patterns not exclusively shared by AD patients, but that overlap with signatures from Huntington’s disease (HD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS),” they further stated.
Initial experiments also showed that cell death triggered by loss of GPX4 can be slowed in cell cultures and in the mouse model using compounds that specifically inhibit ferroptosis. “This pharmacological rescue confirms ferroptosis as the primary driver of neurodegeneration in our models and demonstrates that ferroptosis inhibition can preserve neuronal integrity in vivo, the investigators stated. “Together, these results functionally link ferroptotic stress to neuronal loss and establish a tractable therapeutic strategy to mitigate neurodegeneration in GPX4-deficient states.”
Co-author Tobias Seibt, MD, a nephrologist at LMU University Hospital Munich, stated, “This is an important proof of principle, but it is not yet a therapy.” Added co-first author Adam Wahida, PhD, “In the long term, we can imagine genetic or molecular strategies to stabilize this protective system. For now, however, our work clearly remains in the realm of basic research.”
The study is the result of a research network that has grown over many years, bringing together genetics, structural biology, stem cell research, and neuroscience, with several dozen scientists at multiple sites worldwide. “It has taken us almost 14 years to link a yet-unrecognized small structural element of a single enzyme to a severe human disease,” said Conrad. “Projects like this vividly demonstrate why we need long-term funding for basic research and international multidisciplinary teams if we are to truly understand complex diseases such as dementia and other neurodegenerative disease conditions.”
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