Thursday, March 04, 2021

Study offers an explanation for why the APOE4 gene enhances Alzheimer’s risk

Good news!

"APOE4 is a strong genetic risk factor for many diseases, most notably, late-onset Alzheimer’s disease. Sienski et al. now show that cultured human glia with an APOE4 genotype accumulated unsaturated triglycerides leading to a lipid imbalance. Using genetic screens in yeast, the authors discovered that promoting phospholipid synthesis through choline supplementation of culture medium restored a normal lipid state in APOE4-expressing yeast cells. The authors then demonstrated that choline supplementation also restored lipid homeostasis in human APOE4 astrocytes. These findings suggest that modulating glial metabolism could help to reduce APOE4-associated disease risk."

"The E4 allele of the apolipoprotein E gene (APOE) has been established as a genetic risk factor for many diseases including cardiovascular diseases and Alzheimer’s disease (AD), yet its mechanism of action remains poorly understood. APOE is a lipid transport protein, and the dysregulation of lipids has recently emerged as a key feature of several neurodegenerative diseases including AD. ..."

"One of the most significant genetic risk factors for developing Alzheimer’s disease is a gene called APOE4, which is carried by almost half of all Alzheimer’s patients. A new study from MIT shows that this gene has widespread effects on brain cells’ ability to metabolize lipids and respond to stress. ...
The researchers hope that their findings will lead to clinical studies of choline in people who carry the APOE4 gene, who make up about 14 percent of the overall population. ...
The human gene for APOE, or apolipoprotein E, comes in three versions. While APOE4 is linked to higher risk for Alzheimer’s, APOE2 is considered protective, and APOE3, the most common variant, is neutral. ...
APOE4 astrocytes showed dramatic changes in how they process lipids compared to APOE3. In APOE4 astrocytes, there was a significant buildup of neutral lipids and cholesterol. These astrocytes also accumulated droplets containing a type of lipids called triglycerides, and these triglycerides had many more unsaturated fatty acid chains than normal. These changes all disrupt the normal lipid balance inside the cells. The authors also noted APOE4-dependent lipid disruptions in another important brain cell, microglia. ...
Choline is naturally found in foods such as eggs, meat, fish, and some beans and nuts. The minimum recommended intake of choline is 550 milligrams per day for men and 425 milligrams per day for women, but most people don’t consume that much, Tsai says. The new study offers preliminary evidence that people who carry the APOE4 gene may benefit from taking choline supplements, she says, although clinical trials are necessary to confirm that. ..."

Study offers an explanation for why the APOE4 gene enhances Alzheimer’s risk | MIT News | Massachusetts Institute of Technology The gene variant disrupts lipid metabolism, but in cell experiments the effects were reversed by choline supplements.

Here is the referenced paper:

No comments: