A murine antibacterial orthologue to human bactericidal/permeability-increasing protein (BPI) is expressed in testis, epididymis, and bone marrow.

Andreas Lennartsson, Katrien Pieters, Karina Vidovic, Urban Gullberg

Research output: Contribution to journalArticlepeer-review

Abstract

The bactericidal/permeability-increasing protein (BPI), stored in human neutrophil granulocytes, is cytotoxic against Gram-negative bacteria. Several genes related to BPI cluster on human chromosome 20 and on mouse chromosome 2, but expression and characterization of a BPI ortholog in the mouse have not been reported. We asked whether BPI is structurally and functionally conserved between humans and mice and whether murine BPI might be synthesized in neutrophils as well as in other tissues. We report the isolation of a murine full-length cDNA encoding a 54-kDa protein, showing 53% amino acid identity and 71% similarity, to human BPI. The murine BPI and human BPI genes show a similar exon-intron organization. Murine BPI mRNA was detected in testis, epididymis, and bone marrow, as well as in Sertoli and promyelocytic cell lines. Although levels of BPI mRNA in human and murine testis were comparable, expression in murine bone marrow cells was low as compared with that in human bone marrow. BPI protein showed a cytoplasmic, granular localization in mature neutrophils. BPI gene expression in Sertoli and promyelocytic cells was enhanced several-fold by all-trans retinoic acid. Overexpression of murine BPI in human embryonic kidney 293 cells resulted in antibacterial activity against Escherichia coli, comparable with that obtained with human BPI. In conclusion, it was demonstrated that mouse neutrophils store BPI with antibacterial activity and that murine BPI is also expressed in testis and epididymis.
Original languageEnglish
Pages (from-to)369-377
JournalJournal of Leukocyte Biology
Volume77
Issue number3
DOIs
Publication statusPublished - 2005

Subject classification (UKÄ)

  • Cell and Molecular Biology

Free keywords

  • granulopoiesis
  • leukocyte
  • innate
  • immunity
  • azurophil
  • neutrophil
  • antimicrobial

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