Introduction of human apolipoprotein E4 "domain interaction" into mouse apolipoprotein E

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology
• Neuroscience
• Cardiovascular Science

Background:

• Human apolipoprotein E4 (apoE4) is linked to increased atherosclerosis and Alzheimer's disease risk.
• ApoE4's unique binding preference to lower density lipoproteins is due to an Arg-61/Glu-255 domain interaction.
• Mouse apoE lacks this interaction, behaving like human apoE3 and binding to high density lipoproteins (HDL).

Purpose of the Study:

• To investigate the role of apoE4 domain interaction in atherosclerosis and neurodegeneration.
• To engineer a mouse model that replicates apoE4's specific molecular interactions in vivo.

Main Methods:

• Modified mouse apolipoprotein E (apoE) by replacing Thr-61 with arginine to introduce apoE4 domain interaction.
• Utilized gene targeting in embryonic stem cells to create mice expressing the modified Arg-61 apoE.
• Analyzed lipoprotein binding preferences and apoE abundance in plasma of engineered mice.

Main Results:

• In vitro, the Arg-61 modification shifted mouse apoE binding from HDL to very low density lipoproteins.
• Arg-61 apoE mice exhibited preferential binding to lower density lipoproteins, similar to human apoE4/E3 heterozygotes.
• Heterozygous Arg-61/wild-type apoE mice showed reduced plasma abundance of Arg-61 apoE, indicating faster catabolism.

Conclusions:

• Successfully introduced apoE4 domain interaction into mouse apoE in vivo.
• The developed Arg-61 apoE mouse model accurately reflects key apoE4 phenotypes.
• This novel mouse model provides a valuable tool for studying apoE4's impact on lipoprotein metabolism, atherosclerosis, and neurodegeneration.