Evaluation of the expression of human CAP18 gene during neutrophil maturation in the bone marrow

Abstract

To understand the gene expression of CAP18 (18-kDa cationic antibacterial protein), a member of cathelicidins, we evaluated mRNA and protein expression of CAP18 using human bone marrow cells and mature neutrophils. Northern blot analysis revealed that CAP18 mRNA was expressed more abundantly in bone marrow cells than mature neutrophils, whereas Western blot analysis indicated that CAP18 protein was more abundant in mature neutrophils than bone marrow cells. Consistent with this, in situ hybridization using bone marrow cells demonstrated that the expression of CAP18 mRNA was neutrophil lineage-specific and was observed primarily in myelocytes (G95%) with limited expression in more immature cells (promyelocytes) and mature cells (metamyelocytes, band cells, and segmented neutrophils). Furthermore, immunohistochemical study indicated that, coincident with the increase of CAP18 mRNA levels, CAP18-positive cells increased markedly at myelocyte stage, and the increased levels remained almost constant (G95%) in metamyelocytes, band cells, and segmented neutrophils, although the mRNA levels were remarkably reduced in these cells. Together these observations indicate that CAP18 gene transcription likely occurs lineageand stage-specifically at the myelocyte stage of neutrophil maturation in the bone marrow and results in the synthesis and cytoplasmic accumulation of CAP18, which is present in the subsequent stages of neutrophil maturation. J. Leukoc. Biol. 64: 845-852; 1998.

Regulation of Cathelicidin Gene Expression: Induction by Lipopolysaccharide, Interleukin-6, Retinoic Acid, and Salmonella enterica Serovar Typhimurium Infection

“…Cathelicidin antimicrobial peptides generally are expressed only in granulocytic leukocytes or their precursors (16,(26)(27)(28)37); however, some exceptions exist. Recently, we reported that PR-39 and protegrin mRNA were expressed in several lymphoid tissues in young pigs (39) and the human cathelicidin, LL-37, has been found in the testis (1) and in keratinocytes (9).…”

“…Recently, we reported that PR-39 and protegrin mRNA were expressed in several lymphoid tissues in young pigs (39) and the human cathelicidin, LL-37, has been found in the testis (1) and in keratinocytes (9). In bone marrow, cathelicidin peptides are synthesized during the maturation and differentiation of neutrophil precursors (26,28,41). In this study, we evaluated cathelicidin gene expression by analyzing PR-39 and protegrin mRNA transcription in bone marrow progenitor cells, with transfection studies using the PR-39 promoter, and in Salmonella-challenged animals.…”

“…Most cathelicidins are constitutively expressed in myeloid progenitor cells and stored as pro-peptides in mature neutrophil granules, where few or no transcripts are expressed (26,28,41). However, some cathelicidins are expressed in other tissues and are inducible, such as human LL-37 in the testis (1) and in keratinocytes (9) and PR-39 and protegrin in lymphoid tissues in young pigs (39).…”

Role of CCAAT/Enhancer-Binding Protein Site in Transcription of Human Neutrophil Peptide-1 and -3 Defensin Genes

“…Peripheral blood obtained from healthy volunteers was heparinized, and neutrophils (purity Ͼ 95%) were isolated by Ficoll-Conray centrifugation after dextran sedimentation of erythrocytes (28). In some experiments, neutrophils were resuspended in RPMI 1640 at a final concentration of 5 ϫ 10 6 cells/ml and stimulated with 1 g/ml LPS (from Escherichia coli O127:B8; Difco, Detroit, MI) or 100 U/ml recombinant human TNF-␣ (Genzyme, Boston, MA) at 37°C for 24 h.…”

“…In contrast to the abundance of information on the function of these peptides, their gene regulation is little known. HNP mRNAs are only expressed in immature bone marrow cells and HL-60 human promyelocytic leukemia cells (25)(26)(27)(28). A more recent report has indicated that PU.1 and an unknown Ets-like factor (IRD) are involved in the basal transcription of HNP-1 gene (29).…”