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- Canny, G, et al.
(author)
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Functional and biochemical characterization of epithelial bactericidal/permeability-increasing protein
- 2006
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In: American Journal of Physiology: Gastrointestinal and Liver Physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 290:3, s. 557-567
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Journal article (peer-reviewed)abstract
- Epithelial cells of many mucosal organs have adapted to coexist with microbes and microbial products. In general, most studies suggest that epithelial cells benefit from interactions with commensal microorganisms present at the lumenal surface. However, potentially injurious molecules found in this microenvironment also have the capacity to elicit local inflammatory responses and even systemic disease. We have recently demonstrated that epithelia cells express the anti-infective molecule bactericidal/permeability-increasing protein (BPI). Here, we extend these findings to examine molecular mechanisms of intestinal epithelial cell (IEC) BPI expression and function. Initial experiments revealed a variance of BPI mRNA and protein expression among various IEC lines. Studies of BPI promoter expression in IECs identified regulatory regions of the BPI promoter and revealed a prominent role for CCAAT/enhancer binding protein and especially Sp1/Sp3 in the basal regulation of BPI. To assess the functional significance of this protein, we generated an IEC line stably transfected with full-length BPI. We demonstrated that, whereas epithelia express markedly less BPI protein than neutrophils, epithelial BPI contributes significantly to bacterial killing and attenuating bacterial-elicted proinflammatory signals. Additional studies in murine tissue ex vivo revealed that BPI is diffusely expressed along the crypt-villous axis and that epithelial BPI levels decrease along the length of the intestine. Taken together, these data confirm the transcriptional regulation of BPI in intestinal epithelia and provide insight into the relevance of BPI as an anti-infective molecule at intestinal surfaces.
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| 2. |
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| 3. |
- Lennartsson, Andreas, et al.
(author)
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A murine antibacterial orthologue to human bactericidal/permeability-increasing protein (BPI) is expressed in testis, epididymis, and bone marrow.
- 2005
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In: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 77:3, s. 369-377
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Journal article (peer-reviewed)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.
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| 4. |
- Lennartsson, Andreas, et al.
(author)
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All-trans retinoic acid-induced expression of bactericidal/permeability-increasing protein (BPI) in human myeloid cells correlates to binding of C/EBP{beta} and C/EBP{varepsilon} to the BPI promoter.
- 2006
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In: Journal of Leukocyte Biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 80:1, s. 196-203
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Journal article (peer-reviewed)abstract
- Bactericidal/permeability-inereasing protein (BPI) neutralizes the proinflammatory effects of lipopolysaccharide and is of potential clinical use in the treatment of fulminant Gram-negative infections. BPI is a cationic protein with antibacterial activity stored in azurophil (primary) granules of neutrophil granulocytes. However, the absence of BPI in patients with specific granule deficiency indicates a transcriptional control of BPI, which is distinct from that of other azurophil granule proteins. Accordingly, we demonstrate in vivo that the BPI mRNA level peaks, together with mRNA for specific granule proteins, during the myelocytic and metamyelocytic stage of granulocytic maturation. The human promyelocytic cell line NB4 expresses several azurophil granule proteins, but expression of BPI is undetectable. We show that treatment of NB4 cells with all-trans retinoic acid (ATRA) induces BPI expression at mRNA and at protein level. The induction is dependent on de novo protein synthesis, as judged by sensitivity to cycloheximide. Previous investigations have indicated a potential role of CCAAT/enhancer-binding protein (C/EBP) transcription factors in the regulation of BPI expression. Here, we show that induction of NB4 cells with ATRA correlates to direct binding of C/EBP beta and C/EBP epsilon to the proximal BPI promoter, as determined by electrophoretic mobility shift analysis and chromatin immunoprecipitation. The dependency on C/EBP beta and C/EBP epsilon provides an explanation for delayed BPI mRNA expression, as compared with mRNA of other azurophil granule proteins.
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