ISOLATION OF A NOVEL MACROPHAGE-SPECIFIC GENE BY DIFFERENTIAL CDNA ANALYSIS

To analyze myelomonocytic differentiation we have used the approach of differential cDNA analysis to isolate novel genes that are preferenti ally expressed in mature macrophages. Differential screening of a macr ophage cDNA library led to the identification of a novel cDNA that sho wed macrophage lineage- and differentiation stage-specific expression. Transcripts from the gene, which we have termed Mpg-1, are found at a high level in mature human and murine macrophages and at a moderate l evel in certain myelomonocytic cell lines. The expression of Mpg-1 was found to increase when murine fetal liver hematopoietic progenitor ce lls were induced to differentiate into macrophages. An Mpg-1-specific transcript was not detected in a wide variety of other tissues and cel l lines, The DNA sequence of Mpg-1 (4,214 bp) was obtained from a seri es of overlapping cDNA, 3' rapid amplification of cDNA ends (RACE), an d genomic clones. Primer extension analysis predicted the existence of multiple transcription start sites, ranging from 26 to 117 bp upstrea m of the 5' proximal ATG of the open reading frame. The predicted 669- amino acid, Mpg-1-encoded protein has potential glycosylation and phos phorylation sites in addition to a signal sequence. The core protein i s predicted to have a molecular weight of 71 to 74 kD. Computer-assist ed local similarity searches indicate that Mpg-1 is a novel gene that may share a distant ancestry to perforin, a lytic protein found in cyt otoxic T lymphocytes and natural killer cells. (C) 1995 by The America n Society of Hematology.