New Study Supports Ground-breaking Theory for Alzheimer’s Disease

Understanding Alzheimer’s Disease

According to the 2018 World Alzheimer’s Report, approximately 50 million individuals globally are living with Alzheimer’s disease, with a new diagnosis occurring every three seconds. First identified by Dr. Alois Alzheimer in 1906, the disease continues to be enveloped in mystery.

Alzheimer’s disease is characterized by two primary pathological features: the accumulation of beta-amyloid plaques between neurons and the formation of neurofibrillary tangles within them. This duality forms the basis of the dominant “amyloid hypothesis,” which suggests that these protein accumulations lead to neuronal death, disruptions in neural pathways, and a decline in memory functions. Despite understanding the consequences on neurons, the mechanisms that trigger these protein formations remain largely unknown.

New Insights from Recent Research

A recent study published in ACS Central Science investigates a new theory regarding the early stages of Alzheimer’s disease. Conducted by researchers at the University of California, Riverside, the study identifies lysosomes—specialized organelles within human cells—as crucial players in the disease’s onset.

The Role of Lysosomes

Lysosomes serve as essential recycling units within cells, capturing and breaking down malfunctioning or excess proteins. They internally digest these proteins using enzymes and release the resulting amino acids back into the cytosol for the synthesis of new proteins.

The significance of lysosomes is underscored by the observation of lysosomal storage issues in Alzheimer’s disease, which precede amyloid plaque formation. This lysosomal dysfunction may represent an early stage in the development of Alzheimer’s.

Despite lysosomal storage disorders typically manifesting in childhood, Alzheimer’s is primarily an age-related illness. The research team addressed this disconnect by examining stereochemistry—the spatial arrangement of molecules. Enzyme-substrate interactions require precise fit; thus, any alteration in a protein’s spatial arrangement could hinder the enzyme’s ability to function effectively.

Mechanisms Behind Protein Alteration

The study introduces the concepts of epimerization and isomerization, processes that modify the spatial orientation of molecules without altering their atomic composition. This can be likened to the difference between left and right hands fitting into gloves; if a protein’s orientation changes, it may no longer fit the enzyme’s active site within a lysosome.

Experimental Validation of the Theory

To test their hypothesis, the researchers conducted a series of experiments demonstrating the rapid breakdown of a specific peptide by an enzyme. They then tested the same peptide sequence with a modified amino acid orientation and found that this alteration significantly reduced enzymatic digestion efficiency. The team confirmed these results through further experimentation using mouse microglial cells.

Implications for Alzheimer’s Treatment

Current treatments for Alzheimer’s primarily aim to alleviate symptoms and slow disease progression. Cholinesterase inhibitors, such as donepezil, enhance neuronal firing by increasing acetylcholine availability, while memantine activates neurotransmitter receptors to improve neuronal signal transmission.

However, an effective treatment targeting the disease’s root causes remains elusive due to a lack of understanding of the underlying mechanisms. While this study does not offer a definitive solution, it provides a promising explanation for how Alzheimer’s disease may begin. If the theory holds—suggesting that changes in protein spatial arrangement lead to lysosomal failure and subsequent Alzheimer’s development—this could open new avenues for treatment strategies.

Further research is necessary before any potential cures can be realized, but this study marks a significant first step toward understanding and combating Alzheimer’s disease.

Written by Michael McCarthy

References

1. World Alzheimer’s Report. 2018.
2. Lambeth TR, Riggs DL, Talbert LE, Tang J, Coburn E, Kang AS, et al. Spontaneous Isomerization of Long-Lived Proteins Provides a Molecular Mechanism for the Lysosomal Failure Observed in Alzheimer’s Disease. ACS Central Science. 2019.
Image by Pete Linforth from Pixabay.