Deleted In Azoospermia Gene Research Articles

Association of the mouse infertility factor DAZL1 with actively translating polyribosomes.

The DAZ (Deleted in AZoospermia) gene family was isolated from a region of the human Y chromosome long arm that is deleted in about 10% of infertile men with idiopathic azoospermia. DAZ and an autosomal DAZ-like gene, DAZL1, are expressed in germ cells only. They encode proteins with an RNA recognition motif and with either a single copy (in DAZL1) or multiple copies (in DAZ) of a DAZ repeat. A role for DAZL1 and DAZ in spermatogenesis is supported by their homology to a Drosophila male infertility protein Boule and by sterility of Dazl1 knock-out mice. The biological function of these proteins remains unknown. We found that DAZL1 and DAZ bound similarly to various RNA homopolymers in vitro. We also used an antibody against the human DAZL1 to determine the subcellular localization of DAZL1 in mouse testis. The sedimentation profiles of DAZL1 in sucrose gradients indicate that DAZL1 is associated with polyribosomes, and further capture of DAZL1 on oligo(dT) beads demonstrates that the association is mediated through the binding of DAZL1 to poly(A) RNA. Our results suggest that DAZL1 is involved in germ-cell specific regulation of mRNA translation.

Identification of Two Novel Proteins That Interact with Germ-Cell-Specific RNA-Binding Proteins DAZ and DAZL1

The human DAZ (deleted in azoospermia) gene family on the Y chromosome and an autosomal DAZ-like gene, DAZL1, encode RNA-binding proteins that are expressed exclusively in germ cells. Their role in spermatogenesis is supported by their homology with a Drosophila male infertility gene boule and sterility of Dazl1 knock-out mice. While all mammals contain a DAZL1 homologue on their autosomes, DAZ homologues are present only on the Y chromosomes of great apes and Old World monkeys. The DAZ and DAZL1 proteins differ in the copy numbers of a DAZ repeat and the C-terminal sequences. We studied the interaction of DAZ and DAZL1 with other proteins as an approach to investigate functional similarity between these two proteins. Using DAZ as bait in a yeast two-hybrid system, we isolated two DAZAP (DAZ-associated protein) genes. DAZAP1 encodes a novel RNA-binding protein that is expressed most abundantly in the testis, and DAZAP2 encodes a ubiquitously expressed protein with no recognizable functional motif. DAZAP1 and DAZAP2 bind similarly to both DAZ and DAZL1 through the DAZ repeats. The DAZAP genes were mapped to chromosomal regions 19p13.3 and 2q33–q34, respectively, where no genetic diseases affecting spermatogenesis are known to map.

Human DAZL1 Encodes a Candidate Fertility Factor in Women That Localizes to the Prenatal and Postnatal Germ Cells

The human DAZ (Deleted in AZoospermia) gene family contains a cluster of DAZ genes on the Y chromosome and a single autosomal homologue, DAZL1 (DAZ-Like) that maps to chromosome 3p24. Although the role of the Y chromosome gene family in determining fertility and the expression of the gene family has been well explored in men, little is known of the role of the DAZL1 gene in determining the fertility of women. In mice, loss of function of the homologue of DAZL1 results in the loss of male and female germ cells. In mice, Dazl1 protein is localized to prenatal and postnatal follicles. Here we demonstrate using two antisera that recognize human DAZL1 that the protein is expressed embryonically in germ cells of girls and in mature oocytes. This pattern of expression suggests that the DAZL1 gene is a candidate fertility factor in women and that it would be appropriate to search for mutations in the DAZL1 gene in peripheral blood DNA from women with primary amenorrhoea or premature ovarian failure.

Dazl protein expression in adult rat testis is up-regulated at meiosis and not hormonally regulated.

The Y-chromosomal DAZ (deleted in azoospermia) gene and the autosomal Dazl (deleted in azoospermia-like) gene are two crucial factors for the achievement and maintenance of spermatogenesis. Whereas Y-chromosomal DAZ is present in certain primates, it is lacking in rodents and other species. We have investigated the expression of Dazl protein during spermatogenesis in the adult rat testis using immunohistochemistry. Dazl immunoreactivity was found predominantly in the cytosol of primary pachytene spermatocytes. A weaker but clearly detectable signal was present in intermediate and B spermatogonia and in early spermatocytes from preleptotene to zygotene. The highest expression patterns were observed between stages IV and VIII during the spermatogenic cycle when spermatocytes prepare for the first meiotic division. Specific staining could also be observed in step 11-19 elongating spermatids in the acrosome region. Treatment for 42 days with a potent GnRH-antagonist abolished gonadotrophin secretion and led to a regressed testis, lacking most of the advanced germ cell types such as spermatids but still bearing spermatogonia and spermatocytes. No difference in staining pattern for Dazl protein was observed in GnRH antagonist-treated rats despite the lack of gonadotrophins and substantial impairment of the spermatogenic process, indicating that Dazl expression is clearly hormone-independent. The localization and level of Dazl expression suggests an important role in the regulation of the first meiotic stages of spermatogenesis. The hormone independent onset of expression points to an autonomous cell-cycle event in which Dazl seems to be essential for the entry into meiosis. The presence of Dazl in the acrosome region of elongating spermatids might reflect an unknown role of Dazl as a morphogenetic factor during spermiogenesis.

Molecular and cytogenetic analysis of Y;1 familial translocation

A balanced reciprocal translocation t(Y;1)(q12;q21) was found in an azoospermic male. Using the testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI), the patient had a boy who was found to have the same translocation. They were revealed to have a balanced reciprocal translocation by G-, C-, R- and high resolution banding. Fluorescence in situ hybridiation (FISH) with the probe chromosome Yq heterochromatin and C-banding were confirmed that the breakpoint is in Yq12 heterochromatic region. It was known that deletion of the AZF region of the Y chromosome is most frequent molecularly defined cause of spermatogenic failure. Especially the DAZ (deleted in azoospermia) gene is expressed exclusively in the human male germ line, and is frequently microdeleted in azoospermic men. To detect the small deletion in AZF gene, we studied on seven loci (sY84, 129, 134, 156, 254, 255, 269) including 3 DAZ regions. Also three loci (SRY, DYZ3. DYZ1) on the short arm, centromere and long arm respectively were amplified. Microdeletion of 10 loci was not detected in infertile male and his son. The results indicate that the infertility of this patient could be due to alteration of the sequence order of Y chromosme or to a disturbance of X chromosome inactivation as a result of the proximity to the autosomal portion.

Human DAZL1 encodes a candidate fertility factor in women that localizes to the prenatal and postnatal germ cells.

The human DAZ (Deleted in AZoospermia) gene family contains a cluster of DAZ genes on the Y chromosome and a single autosomal homologue, DAZL1 (DAZ-Like) that maps to chromosome 3p24. Although the role of the Y chromosome gene family in determining fertility and the expression of the gene family has been well explored in men, little is known of the role of the DAZL1 gene in determining the fertility of women. In mice, loss of function of the homologue of DAZL1 results in the loss of male and female germ cells. In mice, Dazl1 protein is localized to prenatal and postnatal follicles. Here we demonstrate using two antisera that recognize human DAZL1 that the protein is expressed embryonically in germ cells of girls and in mature oocytes. This pattern of expression suggests that the DAZL1 gene is a candidate fertility factor in women and that it would be appropriate to search for mutations in the DAZL1 gene in peripheral blood DNA from women with primary amenorrhoea or premature ovarian failure.

Absence of testicular DAZ gene expression in idiopathic severe testiculopathies.

Deletions of the DAZ (deleted in azoospermia) gene family are frequently responsible for male infertility and are generally assessed by analyses of genomic DNA extracted from peripheral leukocytes. The multicopy nature of this gene prevents the distinction of intragenic deletions or deletions not involving the whole DAZ gene cluster. Thus it is still unclear whether each DAZ copy is effectively expressed in the testis. We analysed, by reverse transcription-polymerase chain reaction (RT-PCR), the expression of DAZ, RBM and SRY genes, in testicular cells from infertile men affected by idiopathic severe hypospermatogenesis, obstructive azoospermia and Sertoli cell-only syndrome. Normal mRNA for DAZ, RBM and SRY were observed in obstructive azoospermia, whereas only SRY transcripts were detected when only Sertoli cells were present. Nine out of 10 patients affected by idiopathic severe hypospermatogenesis had normal expression of SRY, RBM and DAZ, while in one patient no DAZ transcript was detected, suggesting that his testiculopathy was related to the absence of DAZ expression. The lack of DAZ mRNA in testicular cells with an apparently normal DAZ gene constitution on DNA extracted from leukocytes may be explained by different hypotheses: (i) not all the copies of the DAZ gene cluster are transcribed in the germ cells and the reported patient had a small deletion involving only the active ones; (ii) the patient may be mosaic for the DAZ gene having a normal constitution in leukocytes and be deleted for DAZ gene in the testis; (iii) abnormalities of DAZ transcription may exist. These findings highlight the intrinsic interpretative difficulties of normal PCR analysis for DAZ and RBM on leukocytes and suggest caution in the use of germ cells for assisted reproductive techniques in these cases to avoid transmission of genetic abnormalities to male offspring.

Male Infertility and the Y Chromosome

Although it has been established since the 1970s thatdeletions of the long arm of the Y chromosome are as-sociated with spermatogenic failure, only in the last fewyears have these regions been described at the molecularlevel. In parallel, Y-linked genes and gene families thatmay explain the phenotypes of men carrying these de-letions have been identified. The first association be-tween spermatogenic failure and an underlying geneticcause was demonstrated by Tiepolo and Zuffardi (1976)in a report of six azoospermic patients carrying micro-scopically detectable deletions of the distal portion ofYq. In four patients, the deletion was de novo—that is,their fathers were tested and were found to carry intactY chromosomes. On this basis, Tiepolo and Zuffardi(1976) proposed the existence of a spermatogenesis fac-tor, called the “azoospermia factor” (AZF), encoded bya gene on distal Yq. However, the assumption that AZFrepresented a single Y-linked gene was overturned whenVogt et al. (1996) observed that Y chromosome micro-deletions follow a certain deletion pattern, with threerecurrently deleted nonoverlapping subregions in prox-imal, middle, and distal Yq11, designated “AZFa,”“AZFb,” and “AZFc,” respectively. In addition, it be-came clear that these deletions were not exclusively as-sociated with azoospermia (Reijo et al. 1996

Microdeletion of the DAZ (deleted in azoospermia) gene or the YRRM (Y chromosome ribonucleic acid recognition motif) gene does not occur in patients with Klinefelter’s syndrome with and without spermatogenesis

Objective: To evaluate the occurrence of microdeletions of the Y chromosome involving the DAZ and YRRM genes in patients with Klinefelter’s syndrome with and without spermatogenesis. Design: Controlled clinical study. Setting: Yamagata University Hospital, Yamagata, Japan. Patient(s): Patients with Klinefelter’s syndrome with spermatogenesis (n = 1) and without spermatogenesis (n = 20) and a control group of men of proven fertility (n = 10). Intervention(s): Blood and semen sampling and testicular biopsy. Main Outcome Measure(s): Semen analysis, polymerase chain reaction amplification of 32 DNA loci on the long arm of the Y chromosome involving the DAZ (deleted in azoospermia) and YRRM (Y chromosome ribonucleic acid recognition motif) genes, and measurement of plasma FSH, LH, and testosterone levels. Result(s): No microdeletions of 32 loci were found in any of the patients with Klinefelter’s syndrome, either with or without spermatogenesis. Plasma LH and FSH levels were abnormally high and testosterone levels were reduced in all the patients with Klinefelter’s syndrome. Conclusion(s): Severe impairment of spermatogenesis in patients with Klinefelter’s syndrome is not caused by microdeletions of the Y chromosome involving the DAZ and YRRM genes.

Is infertility after surgery for cryptorchidism congenital or acquired?

We evaluated whether deletions of the DAZ (deleted in azoospermia) gene, abnormal karyotypes or hypogonadotropic hypogonadism (HH) were demonstrable in infertile men who had undergone surgery in childhood for cryptorchidism with a simultaneous testicular biopsy that demonstrated no or almost no germ cells. In six men with infertility after surgery for cryptorchidism, the adult karyotype and analyses for the DAZ gene, serum follicle-stimulating hormone, luteinizing hormone, and testosterone were performed from a peripheral blood sample. Testicular volume was also measured. All patients exhibited a 46,XY karyotype. There were no deletions of the DAZ-gene, no HH and no testicular atrophy. The infertility was thus not proved to be congenital, and consequently, surgical treatment is indicated before the germ cells disappear from undescended testes. This appears to be before 15 months of age.

Screening for Deletions of the Y Chromosome Involving the DAZ (Deleted in Azoospermia) Gene in Azoospermia and Severe Oligozoospermia

No AccessJournal of UrologyUrological Survey: Abstracts: Male Infertility1 Feb 1998Screening for Deletions of the Y Chromosome Involving the DAZ (Deleted in Azoospermia) Gene in Azoospermia and Severe Oligozoospermia M. Simoni, J. Gromoll, B. Dworniczak, C. Rolf, K. Abshagen, A. Kamischke, C. Carani, D. Meschede, H.M. Behre, J. Horst, and E. Nieschlag M. SimoniM. Simoni More articles by this author , J. GromollJ. Gromoll More articles by this author , B. DworniczakB. Dworniczak More articles by this author , C. RolfC. Rolf More articles by this author , K. AbshagenK. Abshagen More articles by this author , A. KamischkeA. Kamischke More articles by this author , C. CaraniC. Carani More articles by this author , D. MeschedeD. Meschede More articles by this author , H.M. BehreH.M. Behre More articles by this author , J. HorstJ. Horst More articles by this author , and E. NieschlagE. Nieschlag More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(01)63890-4AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "Screening for Deletions of the Y Chromosome Involving the DAZ (Deleted in Azoospermia) Gene in Azoospermia and Severe Oligozoospermia." The Journal of Urology, 159(2S), p. 609 Institutes of Reproductive Medicine and Human Genetics of University, Munster, Germany, and University of Modena, Modena, Italy.© 1998 by American Urological Association, Inc.FiguresReferencesRelatedDetails Volume 159Issue 2SFebruary 1998Page: 609 Advertisement Copyright & Permissions© 1998 by American Urological Association, Inc.MetricsAuthor Information M. Simoni More articles by this author J. Gromoll More articles by this author B. Dworniczak More articles by this author C. Rolf More articles by this author K. Abshagen More articles by this author A. Kamischke More articles by this author C. Carani More articles by this author D. Meschede More articles by this author H.M. Behre More articles by this author J. Horst More articles by this author E. Nieschlag More articles by this author Expand All Advertisement PDF DownloadLoading ...

Screening for Deletions of the Y Chromosome Involving the DAZ (Deleted in Azoospermia) Gene in Azoospermia and Severe Oligozoospermia

Screening for Deletions of the Y Chromosome Involving the DAZ (Deleted in Azoospermia) Gene in Azoospermia and Severe Oligozoospermia

A putative human male infertility gene DAZLA: genomic structure and methylation status.

The DAZLA (DAZ Like Autosomal) gene on human chromosome 3 shares a high degree of homology with the DAZ (Deleted in AZoospermia) gene family on the Y chromosome, a gene family frequently deleted in males with azoospermia or severe oligospermia. The involvement of both DAZ and DAZLA in spermatogenesis is suggested by their testis-specific expression and their homology with a Drosophila male infertility gene, boule. Whereas male infertility resulting from deletion of the DAZ genes on the Y chromosome occurs sporadically, that due to a defective DAZLA gene is expected to be inheritable. The fraction of males with idiopathic azoospermia or oligospermia that harbour mutations in the DAZLA gene remains unknown. As a prerequisite for mutation screening, the genomic structure of the DAZLA gene was elucidated and found to consist of 11 exons spanning 19 kh. The exon/intron boundaries are conserved between DAZ and DAZLA. The 5' end of both genes are hypomethylated in spermatozoa but not in leukocytes or placenta, consistent with the expression pattern of the genes. The genomic structure of DAZLA paves the way for mutation detection in families with autosomal recessive male infertility.

Screening for deletions of the Y chromosome involving the DAZ (Deleted in AZoospermia) gene in azoospermia and severe oligozoospermia

To evaluate the occurrence and prevalence of microdeletions of the Y chromosome involving the DAZ (Deleted in AZoospermia) gene in patients with azoospermia or severe oligozoospermia. Controlled clinical study. University infertility clinic. Infertile men (n = 168) with nonobstructive, idiopathic azoospermia or severe oligozoospermia and normal LH. The control group consisted of proven fathers (n = 86). None. Semen analysis; polymerase chain reaction amplification of the loci sY84, sY143, sY254, and sY255; serum FSH, LH, and T; testicular volume. Deletions involving the sY254 and sY255 DAZ loci were found in three azoospermic patients and two men with sperm concentration < 1 x 10(6)/mL. Serum FSH was elevated in four patients and was normal in one. All five patients had decreased testicular volumes compared with controls. No deletions involving the sY84 and sY143 loci were found. The four loci were amplified normally in the control group. The estimated frequency of deletions involving the DAZ locus is 3% in azoospermic-severely oligozoospermic men consulting an infertility clinic. Polymerase chain reaction amplification of the DAZ locus is useful for the diagnosis of microdeletions of the Y chromosome. Deletions involving more proximal regions of the Y chromosome seem to be rare.

Absence of DAZ gene mutations in cases of non-obstructed azoospermia.

Sequenced-tagged site (STS) analysis of the Y chromosome long arm (Yq) of azoospermic males has identified a minimum common deleted region of several hundred kilobases in approximately 13% of cases. A candidate azoospermia gene, DAZ (deleted in azoospermia), has been isolated from this region. DAZ has also been shown to be absent in severely oligozoospermic males albeit at a much lower frequency. These data, although highly suggestive, do not constitute formal proof that DAZ actually plays a role in azoospermia, as no small intragenic deletions, rearrangements or point mutations in the gene have been found. In this study we report the screening of DNA from 168 azoospermic/oligospermic males for the presence of the DAZ gene. Deletions involving DAZ were detected in five out of 43 (11.6%) azoospermic males whereas none were found in the remaining 125 oligospermic patients. We present the genomic structure of the 5' end of the DAZ gene together with its sequence analysis in 30 non-obstructed azoospermic males. No mutations in DAZ were found in any of the patients sequenced. These data provide no formal proof that DAZ is AZF. Thus the possibility is still valid that another gene(s) mapping to the deletion interval may be responsible for, or contribute to, the observed phenotypes. Alternatively, if DAZ is AZF, they suggest that the most frequent cause of gene inactivation is via large deletions possibly mobilized by Y chromosome repetitive sequences.

The human autosomal gene DAZLA: testis specificity and a candidate for male infertility.

The DAZ (Deleted in AZoospermia) and DAZLA (DAZ-like autosomal) genes may be determinants of male infertility. The DAZ gene on the long arm of the human Y chromosome is a strong candidate for the 'azoospermia factor' (AZF). Its role in spermatogenesis is supported by its exclusive expression in testis, its deletion in a high percentage of males with azoospermia or severe oligospermia, and its homology with a Drosophila male infertility gene boule. No DAZ homologous sequences have been found on the mouse Y chromosome. Instead, a Dazla gene was isolated from mouse chromosome 17 and has been considered to be a murine homologue of DAZ. However, the homology between human DAZ and mouse Dazla is not strong, and Dazla contains only one of the seven DAZ repeats found in DAZ. We report the isolation of the human DAZLA gene by screening a human testis cDNA library with a DAZ cDNA clone. DAZLA encodes only one DAZ repeat and shares high homology with the mouse Dazla, indicating that these two genes are homologues. Using a panel of rodent-human somatic cell lines and fluorescence in situ hybridization, the DAZLA gene was mapped to 3p24, a region not known to share homology with mouse chromosome 17. The DAZLA gene may be involved in some familial cases of autosomal recessive male infertility.

Isolation of a mouse homolog of the human DAZ (Deleted in Azoospermia) gene

Isolation of a mouse homolog of the human DAZ (Deleted in Azoospermia) gene

A murine homologue of the human DAZ gene is autosomal and expressed only in male and female gonads.

We have isolated a homologue of the human Y linked DAZ (deleted in azoospermia) gene from mouse. This gene, Dazla (Daz like, autosomal), is autosomal, located on chromosome 17 and apparently single copy. The predicted protein is highly homologous to that encoded by the DAZ gene in the N-terminal regions of the two proteins and this homology is not confined to the RNA binding domain. Analysis of its expression pattern by reverse transcription PCR shows that the transcript is only detectable in male and female gonads and that testes lacking germ cells do not contain detectable amounts of transcript. We have been unable to detect a Y-linked DAZ homologue in mouse and our results point to the possibility of a role for autosomal RNA binding proteins in mammalian gametogenesis.