Isolation, structure and expression of cDNA and genomic clones for murine eosinophil differentiation factor

Abstract

Eosinophil differentiation factor (EDF) is a recently described regulator affecting eosinophil growth and activation. cDNA clones for murine EDF were isolated by direct expression from libraries prepared from the T cell hybrid NIMP‐TH1. The longest cDNA clone obtained was 1534 bp in length encoding a polypeptide of 133 amino acids. Two variant cDNAs suggesting alternative RNA processing events were detected. The EDF gene was cloned from a genomic λ library and a region of 6727 bp encompassing the gene was sequenced. The gene contains three introns 829, 1875 and 79 bases in length and has numerous repetitive sequences. A common, possible regulatory element, including a conserved decamer, lies adjacent to the TATA boxes of the EDF and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) genes and similar sequences are present in some other lymphokine genes. Recombinant EDF produced in monkey COS cells strongly stimulated the eosinophil lineage and also showed B‐cell‐growth factor II (BCGFII) activity whereas recombinant murine interleukin‐3 and GM‐CSF showed much broader activity towards the different myeloid lineages, were less active on eosinophils and had no BCGFII activity. The BCGFII activity of recombinant EDF together with a comparison of the BCGFII (interleukin‐5) cDNA sequence with that of the EDF cDNA establishes that these two activities are the properties of a single polypeptide. Show more