The chemerin receptor CMKLR1 is a functional receptor for amyloid-β peptide

Area of Science:

• Neuroscience
• Immunology
• Molecular Biology

Background:

• Amyloid-beta 42 (Aβ42) is a key factor in Alzheimer's disease (AD) pathogenesis.
• Microglial cells are involved in clearing Aβ deposits but require specific receptors for chemotaxis and uptake.
• Identifying Aβ42 receptors is crucial for understanding AD progression and developing treatments.

Purpose of the Study:

• To investigate the role of the chemerin receptor CMKLR1 in Alzheimer's disease.
• To determine if CMKLR1 mediates Aβ42-induced microglial migration and Aβ42 clearance.

Main Methods:

• Analysis of CMKLR1 expression in AD patient brains and mouse models.
• Co-localization studies of CMKLR1 and Aβ42 in mouse brain tissue.
• Binding assays using CMKLR1-transfected cells and Aβ42.
• Cell migration assays with primary microglia, microglial cell lines, and CMKLR1-transfected cells.
• Mechanistic studies involving intracellular signaling pathways (ERK1/2, PKA, Akt) and Ca2+ mobilization.
• Internalization studies of the Aβ42-CMKLR1 complex.

Main Results:

• CMKLR1 transcript levels were elevated in AD brains and LPS-treated mouse brains.
• CMKLR1 and Aβ42 were found to co-localize in the hippocampus and cortex of AD mouse models.
• Aβ42 specifically bound to CMKLR1, confirming it as an Aβ42 receptor.
• Aβ42 induced migration of microglia and CMKLR1-expressing cells, but not control cells.
• Aβ42-induced migration involved ERK1/2, PKA, and Akt pathways, independent of Ca2+ mobilization.
• Aβ42-CMKLR1 complex internalization occurred in glial cells, suggesting a role in Aβ42 clearance.

Conclusions:

• Aβ42 activates CMKLR1, triggering glial cell migration towards Aβ deposits.
• CMKLR1 facilitates the clearance of Aβ42 through internalization of the Aβ42-CMKLR1 complex.
• CMKLR1 represents a novel therapeutic target for enhancing Aβ42 clearance and treating Alzheimer's disease.