Three New Studies Shed Light on Alzheimer's Molecular Mechanisms
Recent research from separate teams has unveiled distinct molecular interactions that may play crucial roles in the development and progression of Alzheimer's disease. These findings, published in leading scientific journals, explore how proteins and cellular structures contribute to neurodegeneration.
Tubulin and Neurodegenerative Protein Function
A study from Baylor College of Medicine, published in Nature Communications, investigated the role of the protein tubulin in relation to Tau and alpha-synuclein—proteins linked to Alzheimer's and Parkinson's diseases.
The research team, led by Dr. Lathan Lucas and Dr. Allan Ferreon, used biochemical and biophysical methods, high-resolution microscopy, and neuron-based assays. They found that in the presence of tubulin, Tau and alpha-synuclein shifted toward promoting the assembly of healthy microtubules, rather than forming toxic aggregates.
"Low tubulin levels have been observed in Alzheimer's disease, resulting in fewer microtubules and increased potential for toxic aggregate formation," the researchers noted.
The study was supported by grants from the National Institutes of Health (NINDS subcontract R01 NS105874, NIGMS R01 GM122763) and the Welch Foundation (Q-2097-20220331).
NMDA Receptor and TRPM4 Channel Interaction
A research team led by Prof. Dr. Hilmar Bading at Heidelberg University, in collaboration with Shandong University, published findings in Molecular Psychiatry identifying a molecular interaction involved in Alzheimer's progression.
The study, conducted in an Alzheimer's mouse model, focused on the NMDA receptor and the TRPM4 ion channel. According to the researchers, NMDA receptors at synapses support neuron survival and cognitive function. However, the interaction of TRPM4 with NMDA receptors outside synapses forms a complex that can damage nerve cells. This neurotoxic NMDAR/TRPM4 complex was observed at higher levels in Alzheimer's mouse models compared to healthy controls.
The research team applied a compound named FP802, a "TwinF Interface Inhibitor" previously developed by Prof. Bading's team. Treatment with FP802 disrupted the interaction between TRPM4 and NMDA receptors. Treated animals showed reduced cellular damage, including decreased synapse loss and less mitochondrial structural and functional damage. Learning and memory abilities were reported to remain largely intact, and a reduction in beta-amyloid accumulation was also observed.
Prof. Bading stated that this approach targets a downstream cellular mechanism, the NMDAR/TRPM4 complex, which "contributes to nerve cell death and promotes amyloid deposit formation."
Earlier studies by the team indicated that FP802 provided neuroprotective effects in models of ALS. The research was supported by the German Research Foundation and the European Research Council. The compound requires further pharmacological development, toxicological experiments, and clinical studies before potential human application. Efforts are underway with FundaMental Pharma to refine FP802 for therapeutic use.
Protein Competition Hypothesis
A study led by chemistry professor Ryan Julian at the University of California, Riverside, published in PNAS Nexus, proposed that Alzheimer's disease may develop due to competition between amyloid-beta and tau proteins inside brain cells.
The researchers conducted protein binding studies to examine how amyloid-beta and tau interact around microtubules, the internal cell scaffolds normally stabilized by tau. They observed a sequence resemblance between amyloid-beta peptides and the microtubule-binding region of tau. When mixed with tubulin, amyloid-beta and tau competed for the same binding sites on microtubules. Fluorescently labeled amyloid-beta demonstrated its ability to displace tau from these sites.
The researchers hypothesize that if amyloid-beta peptides displace tau from its binding sites, this could explain tau tangle formation and microtubule destabilization. Such disruption can impair neuron function and lead to cell death. The study suggests that tau does not initiate pathology independently but becomes problematic after displacement by amyloid-beta. This displacement, leading to faulty microtubules, is proposed as a key source of toxicity for brain cells, rather than solely the accumulation of plaques or tangles.
This hypothesis may help to contextualize prior research findings, including results from clinical trials where clearing amyloid-beta plaques did not restore brain functions. If further studies support these findings, it could redirect efforts in developing Alzheimer's treatments. Recent animal studies indicate that lithium may offer a protective effect by stabilizing microtubules.