Growth factor independence-1 (Gfi-1) plays a role in mediating specific granule deficiency (SGD) in a patient lacking a gene-inactivating mutation in the C/EBPε gene

Arati Khanna-Gupta, Hong Sun, Theresa Zibello, Myung Lee Han, Richard Dahl, Laurence A. Boxer, Nancy Berliner

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34 Scopus citations

Abstract

Neutrophil-specific granule deficiency (SGD) is a rare congenital disorder marked by recurrent bacterial infections. Neutrophils from SGD patients lack secondary and tertiary granules and their content proteins and lack normal neutrophil functions. Gene-inactivating mutations in the C/EBPε gene have been identified in 2 SGD patients. Our studies on a third SGD patient revealed a heterozygous mutation in the C/EBPε gene. However, we demonstrate elevated levels of C/EBPε and PU.1 proteins in the patient's peripheral blood neutrophils. The expression of the transcription factor growth factor independence-1 (Gfi-1), however, was found to be markedly reduced in our SGD patient despite the absence of an obvious mutation in this gene. This may explain the elevated levels of both C/EBPε and PU.1, which are targets of Gfi-1 transcriptional repression. We have generated a growth factor-dependent EML cell line from the bone marrow of Gfi-1+/- and Gfi-1 +/+ mice as a model for Gfi-1-deficient SGD, and demonstrate that lower levels of Gfi-1 expression in the Gfi-1+/- EML cells is associated with reduced levels of secondary granule protein (SGP) gene expression. Furthermore, we demonstrate a positive role for Gfi-1 in SGP expression, in that Gfi-1 binds to and up-regulates the promoter of neutrophil collagenase (an SGP gene), in cooperation with wild-type but not with mutant C/EBPε. We hypothesize that decreased Gfi-1 levels in our SGD patient, together with the mutant C/EBPε, block SGP expression, thereby contributing to the underlying etiology of the disease in our patient.

Original languageEnglish (US)
Pages (from-to)4181-4190
Number of pages10
JournalBlood
Volume109
Issue number10
DOIs
StatePublished - May 15 2007

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ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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