Discovery of new human beta-defensins using a genomics-based approach.
Epithelial beta-defensins are broad-spectrum cationic antimicrobial peptides that also act as chemokines for adaptive immune cells. In the human genome, all known defensin genes cluster to a <1 Mb region of chromosome 8p22-p23. To identify new defensin genes, the DNA sequence from a contig of large-insert genomic clones from the region containing human beta-defensin-2 (HBD-2) was analyzed for the presence of defensin genes. This sequence survey identified a novel beta-defensin, termed HBD-3. The HBD-3 gene contains two exons, is located 13 kb upstream from the HBD-2 gene, and it is transcribed in the same direction. A partial HBD-3 cDNA clone was amplified from cDNA derived from IL-1beta induced fetal lung tissue. The cDNA sequence encodes for a 67 amino acid peptide that is approximately 43% identical to HBD-2 and shares the beta-defensin six cysteine motif. By PCR analysis of two commercial cDNA panels, HBD-3 expression was detected in adult heart, skeletal muscle, placenta and in fetal thymus. From RT-PCR experiments, HBD-3 expression was observed in skin, esophagus, gingival keratinocytes, placenta and trachea. Furthermore, in fetal lung explants and gingival keratinocytes, HBD-3 mRNA expression was induced by IL-1beta. Additional sequence analysis identified the HE2 (human epididymis secretory protein) gene 17 kb upstream from the HBD-3 gene. One splice variant of this gene (HE2beta1) encodes a beta-defensin consensus cysteine motif, suggesting it represents a defensin gene product. HE2beta1 mRNA expression was detected in gingival keratinocytes and bronchial epithelia using RT-PCR analysis. The discovery of these novel beta-defensin genes may allow further understanding of the role of defensins in host immunity at mucosal surfaces.
Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
H P
HP
Jia
B C
BC
Schutte
A
A
Schudy
R
R
Linzmeier
J M
JM
Guthmiller
G K
GK
Johnson
B F
BF
Tack
J P
JP
Mitros
A
A
Rosenthal
T
T
Ganz
P B
PB
McCray
D000328:Adult; D000595:Amino Acid Sequence; D000954:Antigens, Surface / Q000235:genetics; D001483:Base Sequence; D002352:Carrier Proteins; D020451:Contig Mapping; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005091:Exons; D005260:Female; D005333:Fetus / Q000378:metabolism; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D005796:Genes / Q000235:genetics; D015698:Genomic Library; D023281:Genomics; D006020:Glycopeptides / Q000235:genetics; D006023:Glycoproteins; D006801:Humans; D007438:Introns; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D033921:Vesicular Transport Proteins; D023083:beta-Defensins / Q000235:genetics*
D000954:Antigens, Surface; D002352:Carrier Proteins; C422950:DEFB103A protein, human; C106641:DEFB4A protein, human; D006020:Glycopeptides; D006023:Glycoproteins; C104585:NPC2 protein, human; D012333:RNA, Messenger; D011994:Recombinant Proteins; C087044:SPAG11A protein, human; D033921:Vesicular Transport Proteins; D023083:beta-Defensins; D004247:DNA