Related Experiment Video
Updated: Jun 3, 2026
Rapid and Refined CD11b Magnetic Isolation of Primary Microglia with Enhanced Purity and Versatility
Published on: April 13, 2017
Apolipoprotein E isoform-dependent microglia migration
Eiron Cudaback1, Xianwu Li, Kathleen S Montine
1Department of Pathology, Neuropathology Division, University of Washington, Seattle, Washington, USA.
Abstract:
Complement component C5a and ATP are potent effectors of microglial movement and are increased in diverse neurodegenerative diseases and at sites of injury. Apolipoprotein E (apoE) influences microglial function, and different human apoE isoforms confer variable risk for development of neurodegenerative disorders, especially Alzheimer's disease. The purpose of this investigation was to test the hypothesis that mouse apoE and human apoE isoforms influence microglial migration. Using primary wild-type and apoE-deficient microglia, we show that C5a- and ATP-stimulated chemotaxis are largely apoE-dependent processes with different molecular bases. Although the C5a-dependent chemotaxis of wild-type microglia was completely blocked by receptor-associated protein (RAP), suggesting apoE receptor involvement, ATP-stimulated migration was unaffected by RAP but was associated with differential ERK phosphorylation. Studies using primary microglia derived from targeted replacement mice "humanized" for the coding exons (protein isoform) of human ε2 (apoE2), ε3 (apoE3), or ε4 (apoE4) allele of APOE revealed that primary mouse microglia expressing apoE4 or apoE2 exhibited significantly reduced C5a- and ATP-stimulated migration compared with microglia expressing human apoE3. This study, for the first time, demonstrates apoE dependence and apoE isoform-specific modulation of microglial migration in response to distinct chemotactic stimuli commonly associated with neurodegenerative disease.
Insights
Apolipoprotein E (apoE) significantly impacts microglial cell migration, a key process in neurodegenerative diseases. Specific human apoE isoforms differentially affect this migration, with apoE4 and apoE2 showing reduced responses compared to apoE3.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Microglial cells are crucial immune cells in the brain, responding to injury and disease.
- Complement component C5a and ATP are known to stimulate microglial migration.
- Apolipoprotein E (apoE) isoforms influence neurodegenerative disease risk, particularly Alzheimer's disease.
Purpose of the Study:
- To investigate the role of mouse and human apolipoprotein E (apoE) isoforms in microglial migration.
- To determine if apoE influences C5a- and ATP-stimulated microglial chemotaxis.
- To elucidate the molecular mechanisms underlying apoE-dependent microglial migration.
Main Methods:
- Primary wild-type and apoE-deficient mouse microglia were used to assess C5a- and ATP-stimulated chemotaxis.
- Receptor-associated protein (RAP) was employed to investigate apoE receptor involvement.
- ERK phosphorylation was analyzed in response to ATP stimulation.
- Primary microglia from humanized mice expressing human apoE2, apoE3, or apoE4 were studied.
Main Results:
- Microglial migration in response to C5a and ATP was found to be largely dependent on apoE.
- C5a-stimulated migration involved apoE receptors, as indicated by RAP blocking.
- ATP-stimulated migration showed differential ERK phosphorylation and was not blocked by RAP.
- Microglia expressing human apoE4 or apoE2 exhibited significantly reduced C5a- and ATP-stimulated migration compared to those expressing apoE3.
Conclusions:
- Microglial migration in response to key chemotactic stimuli is dependent on apolipoprotein E.
- Different human apoE isoforms differentially modulate microglial migration.
- These findings highlight apoE isoform-specific effects on microglial function relevant to neurodegenerative diseases.
