Does the CCL2 rs1024611 G allele increase CCL2/MCP-1 expression and monocyte recruitment?

The CCL2 rs1024611 (-2518 A>G) single-nucleotide polymorphism is a well-characterized functional genetic variant located in the promoter region of the CCL2 (MCP-1) gene.

Molecular and mechanistic pathways

• Transcriptional upregulation: The G allele acts as a gain-of-function variant by creating an additional transcription factor binding motif within the CCL2 distal promoter/enhancer region, resulting in preferential transcription of the G allele over the A allele.
• HuR modulation: The RNA-binding protein HuR interacts with rs1024611-containing regulatory regions to further augment CCL2 expression.
• Receptor activation: Elevated levels of secreted CCL2 act as ligands that bind and activate CCR2 receptors on monocytes. This triggers downstream p38 MAPK and PI3K signaling cascades, which directly drive cell motility and tissue extravasation.

Clinical and expression evidence

• Dose-dependent expression: Functional studies demonstrate a clear genetic gradient in CCL2 mRNA and MCP-1 protein expression (GG > AG > AA). Homozygous GG individuals produce the highest levels of the chemokine, which is especially pronounced during inflammatory or disease-induced stimulation.
• Monocyte chemotaxis: Elevated CCL2 levels establish steep chemotactic gradients that drive increased transendothelial migration and localized tissue recruitment of monocytes. This mechanism is strongly implicated in pathologies characterized by chronic macrophage infiltration, such as atherosclerosis, sepsis, and primary myelofibrosis, though it does not typically alter baseline absolute circulating monocyte counts.

Bottom line

• The CCL2 rs1024611 G allele is a robustly supported functional regulatory variant that drives a dose-dependent increase in CCL2/MCP-1 expression, directly accelerating CCR2-mediated monocyte chemotaxis and tissue recruitment under inflammatory conditions.