New detectors offer insight into cholesterol’s role in Alzheimer’s disease

The search for answers to Alzheimer’s disease and other neurodegenerative disorders remains one of the most pressing goals in brain research. Maciej J. Stawikowski, Ph.D., assistant professor of chemistry and biochemistry at Florida Atlantic University’s Charles E. Schmidt College of Science, believes the key may lie in understanding how cholesterol and other lipids move through cells and affect their communication.

“Lipids and Alzheimer’s are known to be linked,” said Stawikowski, a member of the FAU Stiles-Nicholson Brain Institute. “Lipid imbalance can lead to the formation of amyloid plaques – oversized clumps of protein that disrupt cell function, a hallmark of Alzheimer’s disease.

His team, including Qi Zhang, Ph.D., an associate professor in FAU’s Department of Chemistry and Biochemistry and a member of the FAU Stiles-Nicholson Brain Institute, has focused on developing advanced tools to investigate the relationship between lipids and cellular function.

Cholesterol is a critical component of cell membranes, enabling hormone production, membrane stability, and signaling. However, disturbances in the movement of cholesterol between cellular compartments may play a role in Alzheimer’s disease and other neurodegenerative diseases. To study this, Stawikowski and his team developed new fluorescent cholesterol detectors (CNDs) designed to monitor cholesterol within cell membranes.

A new study, published in Scientific Reports, shows how CND probes can help visualize cholesterol in living cells. By combining computer simulations with live cell imaging, the researchers revealed how different probe designs affect the behavior of the cholesterol probes.

These novel probes could improve our understanding of how cholesterol imbalances contribute to Alzheimer’s disease and other neurodegenerative disorders. By understanding the role of cholesterol in amyloid plaque formation and cell signaling, researchers could develop drugs to modulate lipid activity, potentially leading to new treatments or preventive strategies.

With these probes, we can now visualize the movement and distribution of cholesterol in living cells in unprecedented detail.”

Maciej J. Stawikowski, Ph.D., assistant professor of chemistry and biochemistry at Florida Atlantic University Charles E. Schmidt College of Science, senior author of the study

CND detectors are designed using a 1,8-naphthalimide (ND) scaffold, which is known for its unique fluorescence properties, including large Stokes shifts and sensitivity to environmental changes. This new design allows for modularity, allowing researchers to adapt probes with different head groups and connectors to meet specific experimental requirements. The findings show that modification of headgroups or linkers could enhance the sensitivity and targeting ability of probes.

These detectors are categorized into three different types. Neutral probes tend to aggregate easily, but their cellular uptake is limited. Charged probes, on the other hand, exhibit improved solubility and better interaction with cell membranes. Probes containing hydroxyl groups further enhance hydrogen bonding and lipid interactions, making them particularly effective for studying membrane behavior.

In addition, some variants of CND probes are pH-sensitive, allowing researchers to track the movement of cholesterol in organelles of varying acidity, such as lysosomes and lipid droplets. Compared to traditional cholesterol probes, these tools offer superior fluorescence properties and more precise monitoring of cholesterol dynamics, providing deeper insights into cellular processes.

“Cholesterol is essential for brain function, but its dysregulation could be a key factor in disease progression,” Stawikowski said. “Our new tools provide a window into how cholesterol affects cellular processes and may help identify therapeutic targets for conditions such as Alzheimer’s.”

The research team’s fluorescent cholesterol probes offer applications beyond Alzheimer’s disease, with potential uses in membrane biology, lipid dynamics and drug delivery. By combining experimental techniques with computer simulations, the FAU team laid the groundwork for developing better fluorescent cholesterol probes that can be used to study a wide range of lipid-related disorders.

These probes are versatile tools that can be adapted for different research needs, marking an important step forward in understanding the role of cholesterol in cellular health and disease.

Co-authors of the study are Zhang. Vincente Rubio, Ph.D. Nicholas McInchak; Genesis Fernandez; Dana Benavides? Diana Herrera? and Catherine Jimenez; all FAU alumni; and Haylee Mesa, PhD student, FAU Stiles-Nicholson Brain Institute. and Jonathan Meade, FAU graduate and lab technician.