Human CD68 promoter plus first-intron (IVS-1) expression cassette (~3.0 kb)
Human CD68 promoter/intron cassette combining ~2.9 kb of 5' flanking sequence with the 83-bp CD68 first intron (IVS-1) enhancer. Directs high-level, long-lasting transgene expression in macrophages in vitro and in vivo, and is preferred over the promoter-only construct (cd68) when durable, high-level macrophage-specific expression is required.
Length: 3079 bp
Strength: strong
Tissue: Human monocytes and macrophages (myeloid lineage)
Expression: constitutive
Origin: Human CD68 gene; 2.9-kb promoter + 83-bp first intron (IVS-1)
Characteristics
Combines 2.9 kb of human CD68 5' flanking sequence with the 83-bp first intron (IVS-1) of the CD68 gene positioned downstream of the promoter. In the murine RAW-264 macrophage cell line and in transgenic mice, this promoter-intron cassette directs markedly higher-level and longer-lasting expression of a class A scavenger receptor transgene than the CD68 promoter alone, without loss of macrophage specificity.
Applications: Used to direct high-level, durable macrophage-restricted transgene expression in vitro (e.g., RAW-264 cells) and in vivo in transgenic and virally-transduced mouse macrophages, including for overexpression of scavenger receptors and other macrophage biology studies requiring sustained expression.
Limitations: At roughly 3 kb, this cassette is substantially larger than compact macrophage promoters (e.g., a 150-bp proximal CD68 fragment shown to give strong lentiviral specificity), constraining its use in size-limited vectors such as AAV. The added first intron (IVS-1) increases expression level and durability but does not itself improve macrophage-lineage specificity beyond that of the promoter alone.
