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.
Jia
H P
HP
Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
Schutte
B C
BC
Schudy
A
A
Linzmeier
R
R
Guthmiller
J M
JM
Johnson
G K
GK
Tack
B F
BF
Mitros
J P
JP
Rosenthal
A
A
Ganz
T
T
McCray
P B
PB
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