|
|
||||||||
-Defensin Isoforms in Humans and Mice1





* Division of Integrative Cell Biology, Department of Embryogenesis, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan; and
Department of Geriatric Medicine, Graduate School of Medicine, University of Tokyo, and
Department of Urology, Mitsui Memorial Hospital, Tokyo, Japan
| Abstract |
|---|
|
|
|---|
-defensin (hBD) isoforms by mining the
public human genomic sequences. The predicted peptides conserve the
six-cysteine motif identical with hBD-4, termed hBD-5 and hBD-6. We
also evaluated the characteristics of the mouse homologs of hBD-5,
hBD-6, and HE2
1, termed mouse
-defensin (mBD)-12, mBD-11, and
mouse EP2e (mEP2e). The mBD-12 synthetic peptide showed salt-dependent
antimicrobial activity. We demonstrate the epididymis-specific
expression pattern of hBD-5, hBD-6, mBD-11, mBD-12, and mEP2e. In situ
hybridization revealed mBD-11, mBD-12, and mEP2e expression in the
columnar epithelium of the caput epididymis, contrasting with the
predominant expression of mBD-3 in the capsule or septum of the whole
epididymis. In addition, the regional specificity of mBD-11, mBD-12,
and mEP2e was somewhat overlapping, but not identical, in the caput
epididymis, suggesting that specific regulation may work for each
member of the
-defensin family. Our findings indicated that multiple
-defensin isoforms specifically and cooperatively contribute to the
innate immunity of the urogenital system. | Introduction |
|---|
|
|
|---|
- and
-defensin subfamilies.
Three human
-defensins, human neutrophil peptides
(HNP)3-1, -2, and -3,
were isolated from human neutrophils and showed broad-spectrum
microbicidal activity (1). The first mammalian
-defensin was discovered from the bovine respiratory tract, named
tracheal antimicrobial peptide (2). Subsequently, lingual
antimicrobial peptide was isolated from the bovine tongue
(3).
Four human
-defensin (hBD) isoforms have been identified to date:
hBD-1, -2, -3, and -4 (4, 5, 6, 7). HE2
1, identified as one
major splicing variant of the human EP2 gene, also contains the
specific cysteine motif (8, 9, 10, 11). All hBDs show potent
antimicrobial activity, especially against Gram-negative bacteria,
whereas the function of HE2
1 had not been confirmed (5, 6, 7, 12, 13, 14). In mice, mouse
-defensin (mBD)-1, -2, -3, -4, -5,
-6, -7, -8, -9, -11, -13, and -35 have been identified at the National
Center for Biotechnology Information (NCBI) gene bank, although the
characteristics of mBD-5, mBD-9, mBD-11, mBD-13, and mBD-35 have not
been published (15, 16, 17, 18, 19, 20, 21). mBD-1 and mBD-3 are regarded as
mouse homologs of hBD-1 and hBD-2, respectively, and also showed
antimicrobial activity (16, 18). hBD-1, hBD-2, and hBD-3
showed the widespread distribution in various organs like urogenital
tissues, skin, respiratory tracts, intestinal tracts, testis, and
placenta (22, 23, 24, 25, 26). Although the tissue distribution of
mBD-5, mBD-7, mBD-8, mBD-9, mBD-11, mBD-13, and mBD-35 have not been
evaluated in mice, the other known mBD isoforms also show the
expression in multiple tissues, such as kidney, esophagus, tongue,
trachea, and skeletal muscle (15, 16, 17, 18, 19, 20).
Furthermore, the novel antimicrobial peptide Bin1b was identified in
the rat epididymis and its putative amino acid sequence is included the
conserved six-cysteine motif (27). Bin1b is partially
homologous with HE2
1 and more homologous with the chimpanzee
epididymal protein EP2E in its amino acid sequence (28).
Interestingly, Bin1b showed no expression in the other major organs,
such as the lung or kidney. Subsequently, hBD-4 cDNA was identified and
its expression was also almost confined to the testis with much lower
expression in the gastric antrum (7). These two isoforms
are unique in their confined expression pattern.
Because the defensin genes comprise a large gene cluster in chromosome
8, the genomic sequence is useful to identify novel defensin genes
(11, 29, 30). Recent reports indicate the presence of >25
human or mouse genes that could be encoding
-defensin peptide,
although the characteristics of these genes have not been evaluated
well (31). In this work we report the peculiar
characteristics of multiple epididymis-specific
-defensin isoforms
in humans and mice, including two novel hBD isoforms, named hBD-5 and
hBD-6, and two novel mBD isoforms, named mBD-12 and mouse EP2e (mEP2e),
respectively.
| Materials and Methods |
|---|
|
|
|---|
We obtained the nucleotide sequence of the human genome around
the
-defensin gene cluster in chromosome 8 from the NCBI public
database (NT_019483). This sequence was translated in all six possible
reading frames and was searched for the specific cysteine pattern;
multiple possible
-defensin genes were obtained. We used the
basic local alignment search tool against the expressed sequence tag
(EST) database and obtained a sequence identical with the DEFB6
gene (31). Based on this EST sequence (AW103145, AI910580)
and the corresponding genomic sequence, we designed a pair of specific
intron-spanning primers for RT-PCR (forward primer,
5'-CAGTCATGAGGACTTTCCTC-3'; reverse primer,
5'-AGAAGCTAGGTTATGTATGC-3'). Reverse transcription was performed on
total human epididymis/testis RNA (Clontech Laboratories, Palo
Alto, CA) using Superscript II. The PCR conditions were 94°C for
40 s, 60°C for 30 s, and 72°C for 1 min conducted for 35
cycles.
In addition, we designed two specific primers for RT-PCR based on the genomic sequence of the DEFB5 gene (forward primer, 5'-GTCGTGCAAGCTTGGTCGGG-3'; reverse primer, 5'-CCAGGTCTGCTTCTAAGGCC-3') (31). We performed RT-PCR to evaluate the expression of this gene as described above. Subsequently, we determined the 5' end of this novel cDNA sequence using a 5' RACE kit (Life Technologies, Rockville, MD) performed on total RNA from the human epididymis.
Cloning of the mouse homologs of hBD-5, hBD-6, and HE2
1
We screened the homologous sequence of the DEFB5 gene using the basic local alignment search tool at NCBI and obtained the published full-length cDNA sequence from the adult mouse epididymis (AK020311, RIKEN full-length enriched library; clone 9230103N16) (32).
To identify the homolog of HE2
1, we designed a pair of degenerate
PCR primers from the amino acid sequences conserved between HE2
1 and
Bin1b: forward primer, 5'-GAYRTACCACCKGGAATHAG-3'; reverse primer,
5'-GATACRCARCATCTRTTCCA-3'. RT-PCR was performed on adult mouse
epididymis RNA. The PCR conditions were 94°C for 40 s, 60°C
for 30 s, and 72°C for 1 min conducted for 35 cycles. The
sequencing of the PCR products revealed the homologous fragment with
Bin1b cDNA. We screened the EST library using this novel nucleotide
sequence and obtained the full-length cDNA sequence (AK020333, RIKEN
full-length enriched library; clone 9230111C08) (32).
We also obtained the partial mouse genomic sequence containing the mBD-35 gene from the NCBI database (AL590619). This sequence was translated in all six possible reading frames and detected the homologous genomic sequence with the hBD-6 gene. Based on this genomic sequence, we designed two specific intron-spanning primers to confirm the expression (forward primer, 5'-GCCCTTCAGGTCATGAAGAC-3'; reverse primer, 5'-AGCATCTGCTTCCATCAGGT-3'). RT-PCR was performed as described on the DEFB6 gene. To determine the full-length cDNA sequences of these three mBD isoforms, we used 5'-RACE and 3'-RACE kits on the mouse epididymis RNA (Life Technologies).
Analysis of the genomic organization
As for human genomic sequences and mBD-11 genomic sequences, we used the public sequences at NCBI. As for the mBD-12 and mEP2e genomic sequences, we designed a pair of specific PCR primers from mBD-12 (forward primer, 5'-TGAAGAATCTCCCCTCAAACATGG-3'; reverse primer, 5'-TTCACAAGGCAAAGTTACAG-3') and mEP2e (forward primer, 5'-ATCAGTCACACCTGCTTTCC-3'; reverse primer, 5'-ATCCTTTCACCGGACCTTTG-3'). PCR was performed on the isolated mouse genomic DNA using the Advantage HF-2 PCR kit (Clontech Laboratories). The PCR products were cloned to pCR4-TOPO vector (Invitrogen, Carlsbad, CA) and the inserts were sequenced to determine the splicing site.
Synthesis of mBD-12 mature peptide
We synthesized chemically the putative mBD-12 mature peptide spanning 34 COOH-terminal amino acids of the precursor at the Peptide Institute (Minoh, Japan). The synthetic peptide was air-oxidated for three disulfide bonds. The material, eluted in a single peak on RP-HPLC and confirmed by mass spectroscopy, was lyophilized and dissolved in 0.01% acetic acid.
Analysis of antimicrobial activity
We followed the colony count assay described by Harwig et al. (33) with some modification. Mid-logarithmic-phase Escherichia coli (ATCC 25922 strain) was suspended in 10 mM sodium phosphate buffer to adjust the density to 5 x 107 CFU/ml, and this suspension was mixed with mBD-12 solution. The final sodium concentration of this mixture was 15 mM, and the mBD-12 concentration was adjusted to 2, 20, or 200 µg/ml. As a control, the mixture without mBD-12 was also incubated. After a 2-h incubation of these mixtures at 37°C, the 10-fold serial dilutions were spread over tripticase soy agar plates and incubated at 37°C for 48 h. After counting the numbers of colonies on the plates, we calculated ratios of survived-to-control colony numbers as survival ratios.
The salt sensitivity of the antimicrobial activity was also evaluated. We adjusted the final sodium concentration of the bacterial mixture to 15, 50, 100, or 150 mM with NaCl and incubated the mixture for 2 h with 20 µg/ml mBD-12. As a control, the mixture without mBD-12 was also incubated at each sodium concentration. After the 2-h incubation, the 10-fold serial dilutions were spread over the plates and incubated for 48 h as described above. The procedures were repeated more than four times at each sodium concentration.
RT-PCR
Human epididymis and testis were obtained from the surgical samples of a prostate cancer patient in Mitsui Memorial Hospital (Tokyo, Japan). The institutional review board of Mitsui Memorial Hospital approved this study. We isolated human RNA from these specimens using Isogen (Nippon Gene, Toyama, Japan). We also purchased human RNA of brain, liver, lung, trachea, kidney, heart, and skeletal muscle from Clontech Laboratories. Mouse RNA was isolated from the indicated organs of sexually mature male ICR mice using Isogen (Nippon Gene). A total of 5 µg of each sample was reverse-transcribed by random hexamer primers using Superscript II (Life Technologies).
We designed a pair of specific intron-spanning primers from hBD-5
(forward primer, 5'-TTGGTTCAACTGCCATCAGG-3'; reverse primer,
5'-CCAGGTCTGCTTCTAAGGCC-3'), hBD-4 (forward primer,
5'-CTCCGACTTGCGTCTGCTTC-3'; reverse primer,
5'-CCTGAGCAAAACTTTCGATC-3'), and HE2
1 (forward primer,
5'-TCTGGCTTGCAGTGCTCTTG-3'; reverse primer,
5'-CTTGGGATACTTCAACATCC-3'). As for mouse genes, we also designed a
pair of specific intron-spanning primers from mBD-12 (forward primer,
5'-TGAAGAATCTCCCCTCAAACATGG-3'; reverse primer,
5'-GGAGCATAGCACTTTCGTTTG-3'), mEP2e (forward primer,
5'-ATCAGTCACACCTGCTTTCC-3'; reverse primer,
5'-CACATACTCAAAGCCTTTGG-3'), and mBD-3 (forward primer,
5'-GCTTCAGTCATGAGGATCCATTACCTTC-3'; reverse primer,
5'-GCTAGGGAGCACTTGTTTGCATTTAATC-3'). PCR was performed on 0.5 µl of
reverse transcriptase reaction for a total volume of 25 µl
using Taq polymerase (Takara Shuzo, Otsu, Japan). The
PCR conditions were 94°C for 40 s, 60°C for 30 s, and
72°C for 1 min conducted for the indicated cycles. Amplification of
G3PDH was also performed in parallel as a control.
In situ hybridization
A 290-bp fragment of mBD-11 cDNA, a 700-bp fragment of mBD-12 cDNA, and a 340-bp fragment of mEP2e cDNA were isolated from the mouse epididymis RNA as described above. We also isolated a 300-bp fragment containing mBD-3 exon 2 from bacterial artificial chromosome D11 (Incyte Genomics, Palo Alto, CA) by PCR amplification. Antisense and sense RNA probes were prepared from these fragments by T3 or T7 RNA polymerase using a DIG RNA labeling kit (Roche, Basel, Switzerland).
The mouse epididymis was fixed in 4% paraformaldehyde at 4°C overnight and was cryosectioned at 20 µm. The sections were treated with 1 µg/ml proteinase K for 5 min at 37°C and 2 mg/ml glycine for 30 s, postfixed in 3.7% formaldehyde in PBS for 20 min, and acetylated with 0.25% acetic anhydride in 0.1 M triethanolamine for 10 min. Hybridization with DIG-labeled probe was conducted overnight at 55°C in 5x SSC, 1% SDS, 50% formamide, and 1 mg/ml yeast tRNA containing 1 mg/ml probe. Then, the sections were washed twice in 2x SSC, 1% SDS, 50% formamide and once in 0.2x SSC, 0.1% SDS, 50% formamide at 60°C for 30 min each. The sections were incubated with anti-DIG alkaline phosphatase-conjugated Abs diluted 1/2000 with 100 mM maleic acid (pH 7.5), 50 mM NaCl, 0.1% Tween 20 overnight at 4°C, followed by an alkaline phosphatase reaction step under the following conditions: 50 mg/ml nitroblue tetrazolium chloride, 50 mg/ml 5-bromo-4-chloro-3-indolyl phosphate, 10% (w/v) polyvinylalcohol, 100 mM Tris-Cl (pH 9.5), 50 mM MgCl2, 100 mM NaCl, 0.1% Tween 20. The sections were developed at 37°C in the dark.
| Results |
|---|
|
|
|---|
Based on the public human genomic sequence (NT_019483), we
identified multiple sequences that could be encoding
-defensin
peptide because of its predicted cysteine pattern. We confirmed the
existence of two corresponding transcripts of these putative genes
by RT-PCR. The predicted amino acid sequences of these novel
transcripts contained the specific six-cysteine motif identical with
hBD-4 and we named these novel peptides hBD-5 and hBD-6, although the
transcription initiation site of hBD-6 cDNA has not been
determined, probably due to a too-low amount of hBD-6 mRNA.
The hBD-5 gene was located
74.4 kb from the hBD-2 gene and
19 kb
from the hBD-4 gene (Fig. 1
). The hBD-5
gene encoded its transcript in the antisense direction to the hBD-2,
-3, -4, and HE2
1 genes. The hBD-6 gene was located between the hBD-4
and hBD-5 genes. hBD-5 contained three exons separated by the first
343-bp intron and the second 1248-bp intron while hBD-6 contained two
exons separated by a 3575-bp intron (Fig. 2
). No NF-
B consensus sites were
found within the 5-kb promoter of the hBD-5 gene. The hBD-6 gene
contains the NF-
B consensus sequence (GGGRNTYC) 5 and 1.3 kbp
upstream of the start codon like the hBD-2 gene, which contains
multiple NF-
B binding sites (29, 34).
|
|
1
RIKEN's full-length cDNA sequence from the adult mouse epididymis
(AK020311) exhibited
77% identity with the hBD-5 coding region. We
also confirmed the transcript using RT-PCR, 5'-RACE, and 3'-RACE on the
mouse epididymis RNA. Our sequence analysis contained a 2-nt difference
from RIKEN's sequence in the 3' noncoding region. Because this mouse
homolog corresponded to the Defb12 genomic sequence indicated by
Schutte et al. (31), we named this isoform mBD-12. The
genomic sequencing revealed that the mBD-12 gene was also separated by
one short intron and one relatively long intron like hBD-5. The
nucleotide sequence of the mBD-12 exon 3 coding region was 97.4%
identical (191 of 196) with the corresponding sequence of mBD-35 cDNA
(AJ437650) in the NCBI database, although mBD-12 exon 1 and exon 2
showed no homology with mBD-35. The genomic sequence of the second
mBD-12 intron was also quite different from the mBD-35 genomic
sequence, indicating that different genes encode these transcripts.
Degenerate PCR amplification of the mouse epididymis cDNA with primers
common to HE2
1 and Bin1b revealed a novel
-defensin sequence
homologous with Bin1b. The cDNA sequence was identical with RIKEN's
full-length cDNA sequence of the adult mouse epididymis (AK020333)
(32). We also confirmed the corresponding transcript using
RT-PCR, 5'-RACE, and 3'-RACE on the mouse epididymis RNA. The predicted
amino acid sequence of this cDNA is 68.1% (47 of 69) identical with
chimpanzee EP2E and 88.4% (61 of 69) identical with Bin1b, and we
named this
-defensin isoform mEP2e. The genomic sequence
revealed that the mEP2e gene was composed of only two exons
separated by an
1.2-kb intron, supporting mEP2e correspond to the
EP2E splicing variant in the chimpanzee EP2 gene. The HE2
1 gene was
composed of three exons separated by the first 583-bp intron and the
second 11815-bp intron corresponding to the EP2D isoform (9, 10, 11, 28). The amino acid sequence encoded by the mEP2e exon 2 was
also 67.3% (35 of 52) identical with the corresponding sequence of
HE2
1. We could not detect the mouse variant corresponding to the
EP2D isoform using the 5'-RACE system.
Using the public mouse nucleotide database at the NCBI (AL580619), we
detected the genomic sequence homologous with the hBD-6 gene and
confirmed the corresponding transcript using RT-PCR, 5'-RACE, and
3'-RACE on the mouse epididymis RNA. This mouse homolog was completely
identical with defb11 gene at the NCBI database (AJ437648), named
mBD-11. The predicted amino acid sequence of mBD-11 is 70.9% (46 of
65) identical with hBD-6 corresponding sequence. mBD-11 was composed of
two exons separated by a 2567-bp intron like hBD-6. No NF-
B
consensus sites were found within the 5-kb promoter of the mBD-12
gene.
Comparison of the hBD and mBD isoforms
In Fig. 3
, we compared the partial
amino acid sequences of hBD-5, hBD-6, mBD-11, mBD-12, and mEP2e with
the known
-defensin isoforms whose tissue distribution had
been evaluated. All the isoforms contain the specific cysteine motif
(whose cysteine residues are referred to as C1, C2, C3, C4, C5, and C6
residues in order here).
|
-defensin family, except the specific cysteine motif, there
are some residues relatively conserved, such as the glycine two
positions before the C2 residue (Fig. 3
1, hBD-4, hBD-5, and
hBD-6 in the hBD family showed the epididymis-specific expression
pattern. These isoforms conserve the glutamic acid residue six
positions before the C4 residue and do not conserve the glycine residue
three positions before the C2 residue. These features are rather common
among the potentially new
-defensin isoforms whose expression had
not been established (33). Interestingly,
-defensin
also includes the glutamic acid residue six positions before the C4
residue (1, 35). Antimicrobial activity of synthetic mBD-12 peptide
To confirm the antimicrobial activity of mBD-12, we synthesized a
putative mature peptide of mBD-12. The synthetic peptide showed
bactericidal activity against E. coli. We compared the
potency of mBD-12 with mBD-6 and HNP-1 synthetic peptide, whose data
had been previously reported (20). mBD-12 bactericidal
activity was significantly more potent than HNP-1 at the concentration
of 20 µg/ml (Students t test, p < 0.01)
(Fig. 4
A). This potency was
comparable to other
-defensins because the minimum inhibitory
concentration of recombinant mBD-3 was 16 µg/ml against
E. coli and the effective concentration of hBDs ranged
from 5 to 60 µg/ml (5, 6, 7, 13, 14). The antimicrobial
potency of mBD-12 was significantly reduced at high concentrations of
NaCl like hBD1, hBD-2, hBD-4, mBD-1, and mBD-6 (Students t
test, p < 0.01) (Fig. 4
B) (5, 7, 13, 14).
|
RT-PCR revealed that hBD-5 and hBD-6 were specifically expressed
in the human epididymis (Fig. 5
A). No signal was detected in
the other main organs: brain, trachea, lung, heart, liver, kidney,
skeletal muscle, and testis. This expression pattern was similar to
that of hBD-4. Although a previous report has shown the main expression
of hBD-4 in the testis, our data more precisely indicate the hBD-4
expression in the human epididymis but not in the testis
(7). HE2
1 expression has never been evaluated well. Our
RT-PCR amplification of human epididymis RNA revealed a 546-bp fragment
consistent with HE2
1 and a 470-bp fragment consistent with HE2
1,
confirmed by sequencing. Although weak signals were also detected in
the trachea or lung, the specific amplification of HE2 family was not
confirmed by sequencing in this tissue, indicating that HE2 expression
would be also confined to the epididymis.
|
|
Region specificity of mBD-11, mBD-12, and mEP2e expression in the mouse epididymis
Our evaluation of tissue distribution suggested the importance of
the
-defensin family in the male reproductive organ. To further
investigate the precise distribution of their expression, we isolated
total RNA from the caput, corpus, and caudal region of the adult mouse
epididymis separately. We also isolated total RNA from the mouse
seminal duct, seminal vesicle, and bladder. RT-PCR revealed that mBD-11
and mBD-12 expression was most prominent in the epididymis caput region
and was completely absent in the seminal tract, seminal vesicle, and
bladder (Fig. 6
). mEP2e expression was also most prominent in the caput
region, but the compatible expression was also detected in the corpus
region. RT-PCR of mBD-3 showed ubiquitous expression in the caput,
corpus, and caudal region and even in the seminal tract. mBD-1, mBD-2,
and mBD-6 also showed the ubiquitous expression in the whole epididymis
(data not shown).
To confirm the region-specific expression of mBD-11, mBD-12, and mEP2e
in the mouse epididymis, we analyzed the distribution of mBD-11,
mBD-12, mEP2e, and mBD-3 mRNA at the cellular level using in situ
hybridization. The hybridization signals of the mBD-11, mBD-12, or
mEP2e antisense probe were confined to the epithelial cells of the
mid/distal segment of the caput region, indicating the region
specificity of their expression (Figs. 7
and 8
). Higher magnification also
revealed more complex regulation of mBD-12 or mEP2e expression; i.e.,
some epithelial cells exhibited strong signals whereas the adjacent
epithelial cells exhibited none in the same segment, indicating the
cell specificity of their expression (Fig. 7
D). The sense
probes gave no hybridization signals (data not shown).
|
|
We compared the region specificity among mBD-11, mBD-12, and mEP2e by
hybridization of adjacent sections with each probe. Their signals were
almost colocalized in the mid/distal segment of the caput region (Fig. 8
). However, a narrow portion adjacent to the initial segment exhibited
mBD-12 hybridization signals more intensely and a relatively wide
distal portion exhibited mEP2e hybridization signals more intensely,
consistent with the RT-PCR analysis.
| Discussion |
|---|
|
|
|---|
-defensin isoforms including two novel hBD,
termed hBD-5 and hBD-6, and the mouse homologs of hBD-5, hBD-6, and
HE2
1, termed mBD-12, mBD-11, and mEP2e, respectively.
The organization of gene cluster is a peculiar feature of the defensin
family and prompted us to use the human genomic sequence to search
novel defensin genes. Because multiple isoforms of the
-defensin
family had been identified in human and mouse organs and may compensate
each other for their common functions in part, the overall
identification of
-defensin isoforms is very important to study
their physiological roles.
hBD-5, hBD-6, hBD-4, and HE2
1 were specifically expressed in the
human epididymis. Because the epididymis is anatomically continuous to
the urethra, it is always at the risk of ascending microbial invasion.
Acute epididymitis is a common sexually transmitted disease, caused by
bacterial infection of the epididymis. Therefore, host defense against
a bacterial pathogen would be very important in the epididymis for the
protection of spermatozoa.
Our identification of the novel mBD, mBD-12, and mEP2e would also be
noteworthy because animal models are very useful to understand the
physiological and pathological significance of these peptides. The
comparison of the genomic organization of HE2
1 and mEP2e revealed
that HE2
1 and mEP2e would be included in different message variants.
Although the genomic sequence of the HE2 gene indicated the possible
existence of another promoter within the second intron of the HE2
1
gene, no transcripts corresponding to the EP2e isoform have been
identified in humans. Considering that no splicing variants
corresponding to the HE2
1 isoform were detected in mice, the major
transcript would be different between humans and mice, at least at a
basal state.
Our identification of the epididymis-specific
-defensin isoforms
clarified the existence of two groups in the
-defensin family:
epididymis-specific isoforms and the other isoforms. The former
includes HE2
1, hBD-4, hBD-5, and hBD-6 and the latter includes
hBD-1, hBD-2, and hBD-3 in humans. Interestingly, the
epididymis-specific
-defensin genes were located within a region
encompassing
40 kb in the human defensin gene cluster on chromosome
8. In mice, this report first indicated that mBD-11, mBD-12, and mEP2e
are expressed, and that their expression is epididymis specific.
Between the two groups, some different features are present in their
amino acid sequences. First, the amino acid sequences of the
epididymis-specific
-defensin isoforms were well conserved between
humans and mice in comparison with the other
-defensin isoforms.
Although mBD-3 had been regarded as a hBD-2 homolog, the amino acid
sequence identity was only 40%. In contrast, mBD-11, mBD-12, and mEP2e
were >65% identical with their human homologs. Second, some amino
acid residues are different between the two groups. The glutamic acid
residue is conserved in six positions before the C4 residue in the
epididymis-specific
-defensin isoforms, and this feature is
conserved even in the
-defensin family. Although few conserved
residues have been indicated, except the cysteine motif, between
the
-defensin and
-defensin families and it had been questioned
whether the two families have really descended from a single ancestral
gene, this common feature would support the evolutionary continuity
between the
-defensin and
-defensin families (36).
In addition, these features would reflect the existence of some
specific microenvironmental condition of host defense in the
epididymis.
Our evaluation of the mBD-11, mBD-12, mEP2e, and mBD-3 expression
pattern in the epididymis revealed mBD-11, mBD-12, and mEP2e expression
in the epithelial cells of the mid/distal segment of the caput region
and mBD-3 expression in the capsule and septum of the whole epididymis.
These findings also clarify the different features between the
epididymis-specific isoforms and the other
-defensin isoforms.
More interestingly, mBD-11, mBD-12, and mEP2e were expressed in
different regions, although major portions of the middle segment
expressed both genes. In general, the epididymis displays a highly
region-specific and cell-specific pattern of gene expression (37, 38). This spatial regulation would make different luminal
environments, and in these specific environments the specific functions
of the epididymis would be conducted, such as regulation of sperm
maturation, storage of mature spermatozoa, and protection from
pathogens or reactive oxygen. Our results indicate that some different
regional regulation would be also working among the members of the
epididymis-specific
-defensin family, suggestive of their roles in
the specific functions of the epididymis, although this issue remains
to be investigated more clearly.
| Acknowledgments |
|---|
| Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Hiroki Kurihara, Division of Integrative Cell Biology, Department of Embryogenesis, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto-shi, Kumamoto 860-0811, Japan. E-mail address: kurihara{at}kaiju.medic.kumamoto-u.ac.jp ![]()
3 Abbreviations used in this paper: HNP, human neutrophil peptide; hBD, human
-defensin; mBD, mouse
-defensin; mEP2e, mouse EP2e; EST, expressed sequence tag. ![]()
Received for publication April 1, 2002. Accepted for publication June 28, 2002.
| References |
|---|
|
|
|---|
-defensin from human plasma. FEBS Lett. 368:331.[Medline]
-defensin-3, a novel human inducible peptide antibiotic. J. Biol. Chem. 276:5707.
-defensin 4: a novel inducible peptide with a specific salt-sensitive spectrum of antimicrobial activity. FASEB J. 15:1819.
and HE2
, new members of an epididymis-specific family of androgen-regulated proteins in the human. Endocrinology 141:1245.
-defensins using a genomics-based approach. Gene 263:211.[Medline]
-defensin-1 is a salt-sensitive antibiotic in lung that is inactivated in cystic fibrosis. Cell 88:553.[Medline]
-defensin-1: an antimicrobial peptide of urogenital tissues. J. Clin. Invest. 101:1633.[Medline]
-defensin 2 is a salt-sensitive peptide antibiotic expressed in human lung. J. Clin. Invest. 102:874.[Medline]
-defensin 1. FEBS Lett. 413:45.[Medline]
-defensin 1 is a salt-sensitive antimicrobial peptide in epithelia of the lung and urogenital tract. Infect. Immun. 66:1225.
defensin, Defb2, which is upregulated in the airways by lipopolysaccharide. FEBS Lett. 442:112.[Medline]
-defensin 3 is an inducible antimicrobial peptide expressed in the epithelia of multiple organs. Infect. Immun. 67:3542.
-defensin expressed in tongue, esophagus, and trachea. J. Biol. Chem. 275:33314.
-defensin, mBD-6, predominantly expressed in skeletal muscle. J. Biol. Chem. 276:315.
-defensins reveals structural conservation in the absence of significant sequence similarity. Protein Sci. 10:2470.[Medline]
-defensin hBD-1 in human secretory glands and epithelial cells. FEBS Lett. 396:319.[Medline]
-defensin. Am. J. Respir. Cell Mol. Biol. 16:343.[Abstract]
-defensins hBD-1 and hBD-2 in intestinal epithelium. J. Immunol. 163:6718.
-defensin (human
-defensin 3) with specific antimicrobial activity: its interaction with plasma membranes of Xenopus oocytes and the induction of macrophage chemoattraction. Cell Tissue Res. 306:257.[Medline]
-defensin HBD-2 gene and its expression at sites of inflammation. Gene 222:237.[Medline]
-defensin gene clusters using a computational search strategy. Proc. Natl. Acad. Sci. USA 99:2129.
-defensin-2 expression in human tracheobronchial epithelium. J. Biol. Chem. 275:29731.This article has been cited by other articles:
![]() |
A. Rodrigues, D. B.C. Queiroz, L. Honda, E. J. R. Silva, S. H. Hall, and M. C. W. Avellar Activation of Toll-Like Receptor 4 (TLR4) by In Vivo and In Vitro Exposure of Rat Epididymis to Lipopolysaccharide from Escherichia Coli Biol Reprod, December 1, 2008; 79(6): 1135 - 1147. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. Nagaoka, F. Niyonsaba, Y. Tsutsumi-Ishii, H. Tamura, and M. Hirata Evaluation of the effect of human {beta}-defensins on neutrophil apoptosis Int. Immunol., April 1, 2008; 20(4): 543 - 553. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Harder, R. Glaser, and J.-M. Schroder Review: Human antimicrobial proteins effectors of innate immunity Innate Immunity, December 1, 2007; 13(6): 317 - 338. [Abstract] [PDF] |
||||
![]() |
Y. Radhakrishnan, M. A. Fares, F. S. French, and S. H. Hall Comparative genomic analysis of a mammalian {beta}-defensin gene cluster Physiol Genomics, August 20, 2007; 30(3): 213 - 222. [Abstract] [Full Text] [PDF] |
||||
![]() |
M.A. Palladino, T.A. Johnson, R. Gupta, J.L. Chapman, and P. Ojha Members of the Toll-Like Receptor Family of Innate Immunity Pattern-Recognition Receptors Are Abundant in the Male Rat Reproductive Tract Biol Reprod, June 1, 2007; 76(6): 958 - 964. [Abstract] [Full Text] [PDF] |
||||
![]() |
S Rodriguez-Martinez, M E Cancino-Diaz, and J C Cancino-Diaz Expression of CRAMP via PGN-TLR-2 and of {alpha}-defensin-3 via CpG-ODN-TLR-9 in corneal fibroblasts. Br. J. Ophthalmol., March 1, 2006; 90(3): 378 - 382. [Abstract] [Full Text] [PDF] |
||||
![]() |
X.-M. Chen, S. P. O'Hara, J. B. Nelson, P. L. Splinter, A. J. Small, P. S. Tietz, A. H. Limper, and N. F. LaRusso Multiple TLRs Are Expressed in Human Cholangiocytes and Mediate Host Epithelial Defense Responses to Cryptosporidium parvum via Activation of NF-{kappa}B J. Immunol., December 1, 2005; 175(11): 7447 - 7456. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. A. Patil, Y. Cai, Y. Sang, F. Blecha, and G. Zhang Cross-species analysis of the mammalian {beta}-defensin gene family: presence of syntenic gene clusters and preferential expression in the male reproductive tract Physiol Genomics, September 21, 2005; 23(1): 5 - 17. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Niyonsaba, H. Ushio, I. Nagaoka, K. Okumura, and H. Ogawa The Human {beta}-Defensins (-1, -2, -3, -4) and Cathelicidin LL-37 Induce IL-18 Secretion through p38 and ERK MAPK Activation in Primary Human Keratinocytes J. Immunol., August 1, 2005; 175(3): 1776 - 1784. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Sang, M. T. Ortega, F. Blecha, O. Prakash, and T. Melgarejo Molecular Cloning and Characterization of Three {beta}-Defensins from Canine Testes Infect. Immun., May 1, 2005; 73(5): 2611 - 2620. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. S. McIntosh, J. E. Cade, M. Al-Abed, V. Shanmuganathan, R. Gupta, A. Bhan, P. J. Tighe, and H. S. Dua The Spectrum of Antimicrobial Peptide Expression at the Ocular Surface Invest. Ophthalmol. Vis. Sci., April 1, 2005; 46(4): 1379 - 1385. [Abstract] [Full Text] [PDF] |
||||
![]() |
E Furrie, S Macfarlane, A Kennedy, J H Cummings, S V Walsh, D A O'Neil, and G T Macfarlane Synbiotic therapy (Bifidobacterium longum/Synergy 1) initiates resolution of inflammation in patients with active ulcerative colitis: a randomised controlled pilot trial Gut, February 1, 2005; 54(2): 242 - 249. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. C. W. Avellar, L. Honda, K. G. Hamil, S. Yenugu, G. Grossman, P. Petrusz, F. S. French, and S. H. Hall Differential Expression and Antibacterial Activity of Epididymis Protein 2 Isoforms in the Male Reproductive Tract of Human and Rhesus Monkey (Macaca mulatta) Biol Reprod, November 1, 2004; 71(5): 1453 - 1460. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. K. Meyerholz, B. Grubor, J. M. Gallup, H. D. Lehmkuhl, R. D. Anderson, T. Lazic, and M. R. Ackermann Adenovirus-Mediated Gene Therapy Enhances Parainfluenza Virus 3 Infection in Neonatal Lambs J. Clin. Microbiol., October 1, 2004; 42(10): 4780 - 4787. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. L. Mueller, D. R. Ripoll, C. F. Aquadro, and M. F. Wolfner Comparative structural modeling and inference of conserved protein classes in Drosophila seminal fluid PNAS, September 14, 2004; 101(37): 13542 - 13547. [Abstract] [Full Text] [PDF] |
||||
![]() |
C.-Y. Kao, Y. Chen, P. Thai, S. Wachi, F. Huang, C. Kim, R. W. Harper, and R. Wu IL-17 Markedly Up-Regulates {beta}-Defensin-2 Expression in Human Airway Epithelium via JAK and NF-{kappa}B Signaling Pathways J. Immunol., September 1, 2004; 173(5): 3482 - 3491. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. K. Zaalouk, M. Bajaj-Elliott, J. T. George, and V. McDonald Differential Regulation of {beta}-Defensin Gene Expression during Cryptosporidium parvum Infection Infect. Immun., May 1, 2004; 72(5): 2772 - 2779. [Abstract] [Full Text] [PDF] |
||||
![]() |
K.-i. Ogushi, A. Wada, T. Niidome, T. Okuda, R. Llanes, M. Nakayama, Y. Nishi, H. Kurazono, K. D. Smith, A. Aderem, et al. Gangliosides Act as Co-receptors for Salmonella enteritidis FliC and Promote FliC Induction of Human {beta}-Defensin-2 Expression in Caco-2 Cells J. Biol. Chem., March 26, 2004; 279(13): 12213 - 12219. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Zaballos, R. Villares, J. P. Albar, C. Martinez-A, and G. Marquez Identification on Mouse Chromosome 8 of New {beta}-Defensin Genes with Regionally Specific Expression in the Male Reproductive Organ J. Biol. Chem., March 26, 2004; 279(13): 12421 - 12426. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Bourgeon, B. Evrard, M. Brillard-Bourdet, D. Colleu, B. Jegou, and C. Pineau Involvement of Semenogelin-Derived Peptides in the Antibacterial Activity of Human Seminal Plasma Biol Reprod, March 1, 2004; 70(3): 768 - 774. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Narayanan, W. L. Miller, and A. M. McDermott Expression of Human {beta}-Defensins in Conjunctival Epithelium: Relevance to Dry Eye Disease Invest. Ophthalmol. Vis. Sci., September 1, 2003; 44(9): 3795 - 3801. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. M. McDermott, R. L. Redfern, B. Zhang, Y. Pei, L. Huang, and R. J. Proske Defensin Expression by the Cornea: Multiple Signalling Pathways Mediate IL-1{beta} Stimulation of hBD-2 Expression by Human Corneal Epithelial Cells Invest. Ophthalmol. Vis. Sci., May 1, 2003; 44(5): 1859 - 1865. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |