In a new study Arizona State University–Banner Health neuroscientist Salvatore Oddo and his colleagues from Phoenix’s Translational Genomics Research Institute (TGen) – as well as the University of California, Irvine, and Mount Sinai in New York – have identified a new way for brain cells to become fated to die during Alzheimer’s disease.

The research team has found the first evidence that the activation of a biological pathway called necroptosis, which causes neuronal loss, is closely linked with Alzheimer’s severity, cognitive decline and extreme loss of tissue and brain weight that are all advanced hallmarks of the disease.

“We anticipate that our findings will spur a new area of Alzheimer’s disease research focused on further detailing the role of necroptosis and developing new therapeutic strategies aimed at blocking it,” said Oddo, the lead author of this study, and scientist at the ASU–Banner Neurodegenerative Disease Research Center at the Biodesign Institute and associate professor in the School of Life Sciences.

The findings appeared in the journal Nature Neuroscience.

Necroptosis, which causes cells to burst from the inside out and die, is triggered by a triad of proteins. It has been shown to play a central role in multiple sclerosis and Lou Gehrig’s disease (amyotrophic lateral sclerosis, or ALS), and now for the first time, also in Alzheimer’s disease.

“There is no doubt that the brains of people with Alzheimer’s disease have fewer neurons,” said Oddo. “The brain is much smaller and weighs less; it shrinks because neurons are dying. That has been known for 100 years, but until now, the mechanism wasn’t understood.” Necroptosis was first identified as a result of inflammation, a common malady in Alzheimer’s.

Three critical proteins are involved in the initiation of necroptosis, known as RIPK1, RIPK3 and MLKL. The study describes a key event in the process of necroptosis when RIPK1 and RIPK3 form a filamentous structure known as the necrosome.

The formation of the necrosome appears to jump–start the process of necroptosis. It activates MLKL, which affects the cell’s mitochondria, eventually leading to cell death.

Winnie Liang, TGen assistant professor, director of TGen Scientific Operations and director of TGen's Collaborative Sequencing Center, said MLKL executes necroptosis to ultimately cause cell death.

“In this study, we show for the first time that necroptosis is activated in Alzheimer’s disease, providing a plausible mechanism underlying neuronal loss in this disorder,” said Liang, who contributed to the study’s gene expression analyses.

Three critical proteins are involved in the initiation of necroptosis, known as RIPK1, RIPK3 and MLKL. The study describes a key event in the process of necroptosis when RIPK1 and RIPK3 form a filamentous structure known as the necrosome.

The formation of the necrosome appears to jump–start the process of necroptosis. It activates MLKL, which affects the cell’s mitochondria, eventually leading to cell death.

Winnie Liang, TGen assistant professor, director of TGen Scientific Operations and director of TGen's Collaborative Sequencing Center, said MLKL executes necroptosis to ultimately cause cell death.

The study opens a new window on Alzheimer’s research and offers hope for therapies targeting cell loss in the brain, an inevitable and devastating outcome of Alzheimer’s progression.

Oddo stresses that RIPK1, RIPK3 and MLKL are among many potential drug targets, and others will likely follow as the links between necroptosis and Alzheimer’s become clearer.