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PubMedDate not supplied

Molecular analysis of SRY gene in Brazilian 46,XX sex reversed patients: absence of SRY sequence in gonadal tissue.

BACKGROUND: The importance of the Y chromosome in male determination has been well established for a long time. The presence of a translocation of chromosomal material encoding the Testis-Determining Factor from Y to another chromosome has been one of the hypothesis to explain testicular development in XX sex-reversed patients. MATERIAL AND METHODS: In the present study, we searched for SRY sequence in genomic DNA isolated from peripheral leukocytes in eleven 46,XX true hermaphrodites and four 46,XX males (only one with ambiguous genitalia). We also analyzed the presence of SRY sequence in fresh gonadal tissues from two 46,XX true hermaphrodites. RESULTS: SRY sequence was absent in DNA blood samples of all true hermaphrodites and in testicular and ovarian tissues of two cases studied. Of the four 46,XX males, two with normal male external genitalia were SRY positive. CONCLUSIONS: We did not identify the SRY gene in 46,XX true hermaphrodites and 46,XX males with ambiguous genitalia, therefore SRY translocation to X chromosome or autosome is unlikely. Hidden Y mosaicism in gonadal tissues was also ruled out in two cases, suggesting that cryptic SRY mosaicism in gonadal tissues is not the usual mechanism responsible for testicular development in patients with 46,XX true hermaphroditism. However, SRY gene was identified in two 46,XX males with male external genitalia showing that SRY gene determined their male phenotype. Despite the recent advances in the knowledge of the role of several genes involved in sexual determination we are still unable to explain the cause of most of Y-chromosome-negative 46,XX sex-reversed patients.

DNA-Binding Proteins↗
PubMed2004

DNA methylation-mediated control of Sry gene expression in mouse gonadal development.

DNA methylation at CpG sequences is involved in tissue-specific and developmentally regulated gene expression. The Sry (sex-determining region on the Y chromosome) gene encodes a master protein for initiating testis differentiation in mammals, and its expression is restricted to gonadal somatic cells at 10.5-12.5 days post-coitum (dpc) in the mouse. We found that in vitro methylation of the 5'-flanking region of the Sry gene caused suppression of reporter activity, implying that Sry gene expression could be regulated by DNA methylation-mediated gene silencing. Bisulfite restriction mapping and sodium bisulfite sequencing revealed that the 5'-flanking region of the Sry gene was hypermethylated in the 8.5-dpc embryos in which the Sry gene was not expressed. Importantly, this region was specifically hypomethylated in the gonad at 11.5 dpc, while the hypermethylated status was maintained in tissues that do not express the Sry gene. We concluded that expression of the Sry gene is under the control of an epigenetic mechanism mediated by DNA methylation.

Animals↗
PubMed2006

Identification and molecular modelling of a novel familial mutation in the SRY gene implicated in the pure gonadal dysgenesis.

SRY gene is responsible for initiating male sexual differentiation. The protein encoded by SRY contains a homeobox (HMG) domain, which is a DNA-binding domain. Mutations of the SRY gene are reported to be associated with XY pure gonadal dysgenesis. The majority of these are de novo mutations affecting only one individual in a family. Only a small subset of mutations is shared between the father and one or more of his children. Most of these familial mutations are localized within the HMG box and only two are at the N-terminal domain of the SRY protein. Herein, we describe a young girl with pure gonadal dysgenesis and her father carrying a novel familial mutation in the SRY gene at codon number 3. This mutation is resulting in a serine (S) to leucine (L) substitution. The secondary structure of the SRY protein was carried out by protein modelling studies. This analysis suggests, with high possibility, that the N-terminal domain of the SRY protein, where we found the mutation, could form an alpha-helix from amino acid in position 2 to amino acid in position 13. The secondary structure prediction and the chemical properties of serine to leucine substitution stands for a potential disruption of this N-terminal alpha-helix in the SRY protein. This mutation could have some role in impeding the normal function of the SRY protein.

Adolescent↗
PubMed2002

SRY gene expression in the ovotestes of XX true hermaphrodites.

PURPOSE: The pathogenesis of 46 XX true hermaphroditism is uncertain and the role of the SRY gene in ovotestis development has not been thoroughly evaluated. We ascertained the presence of the SRY gene and SRY protein in the ovotestis. MATERIALS AND METHODS: We evaluated 8 ovotestes by cytogenetic analysis of fibroblast cell culture and analysis of gonadal tissue by polymerase chain reaction to detect the SRY gene and by immunohistochemistry with a monoclonal antibody to human recombinant SRY protein. RESULTS: Fibroblast culture of the ovotestes demonstrated a 46XX karyotype. By polymerase chain reaction all 8 ovotestes demonstrated the SRY gene at low levels. By immunohistochemistry SRY protein was detected in all ovotestes, predominantly in Sertoli and germ cells. CONCLUSIONS: The SRY gene has a role in ovotestis genesis. Mosaicism with a Y bearing cell line in the gonad is a possible explanation and further study is warranted.

Adolescent↗
PubMed2005

Two novel mutations in SRY gene form Chinese sex reversal XY females.

The SRY gene (sex determining region on Y chromosome) acts as TDF and is required for regulating male sex determination. SRY represents a transcription factor belonging to the superfamily of genes sharing the HMG-box motif (high-mobility group-box), which acts as DNA binding region. Deletion and inactivating mutations of SRY are among the known causes of XY sex reversal. Here, we described the screening of 10 patients who presented with 46,XY sex reversal for mutations in open reading frame (ORF) of SRY gene. DNA was isolated from blood samples using standard techniques. A 609 bp fragment from the central portion of the SRY gene was amplified, using primers XES-2 and XES-7. The amplified PCR fragments were cloned into the pUCm-T vectors, and direct sequencing were carried out on an ABI 377-3 automated DNA sequencer to detect the mutation. PCR-restriction enzyme digestion was applied to detect the results of DNA sequencing. In two patients,de novo mutations led to an amino acid substitution. An A was replaced by a G in codon 38 upstream of the 5' border outside the HMG box of the SRY gene, resulting in the replacement of the amino acid glutamate by glycine. Another heterozygous T to A transition at the nucleotide position +387 which encodes for a Tyrosine (Tyr) instead of a Term, whereas her father was proven to have the wild-type sequence. These point mutations have been confirmed with PCR-restrict enzyme method. As demonstrated by the Human Gene Mutation Database analysis,homology search, and review of the literature, these two mutations were not described previously and brought the total number of SRY gene nucleotide substitutions (missense/nonsense) to 45. These findings indicated that these amino acid substitutions may be responsible for the sex reversal,not only inside the HMG-box but also outside the HMG-box. The two novel mutations in SRY gene provided valuable information for understanding the molecular mechanism of the patient with 46,XY female sex reversal.

Amino Acid Substitution↗
PubMed1994

The testis-determining gene, SRY, exists in multiple copies in Old World rodents.

SRY is a unique gene on the Y chromosome in most mammalian species including the laboratory mouse, Mus musculus, and the closely related European wild mouse species M. spicilegus, M. macedonicus, and M. spretus. In contrast, SRY is present in 2-6 copies in the more distantly related Asian mouse species M. caroli, M. cervicolor, and M. cookii and in 2-13 copies in the related murid species Pyromys saxicola, Coelomys pahari, Nannomys minutoides, Mastomys natalensis, and Rattus norvegicus. Copy numbers do not correlate with known phylogenetic relationships suggesting that SRY has undergone a rapid and complex evolution in these species. SRY was recently proposed as a molecular probe for phylogenetic inferences. The presence of multiple SRY genes in a wide range of murid species and genera, and at least one cricetid species, necessitates caution in the use of SRY for phylogenetic studies in the Rodentia unless it is ascertained that multiple SRY genes do not exist.

Animals↗
PubMed2005

Molecular evaluation of the SRY gene for gonads of patients with mixed gonadal dysgenesis.

AIM: To determine whether the SRY gene is present in the gonads of patients with mixed gonadal dysgenesis (MGD). METHODS: Molecular analysis was performed in three patients with MGD. Polymerase chain reactions were used to test for the presence of the SRY gene in the peripheral lymphocytes, testes and streak gonads. RESULTS: Chromosome analysis revealed 45,XO/46,XY in two patients, and 46,XY in the third patient. In the peripheral lymphocytes and testicular tissue, the SRY sequences were positive in all cases. However, the SRY sequence was detected in the streak gonad in only two of the three patients. CONCLUSIONS: It is interesting that we identified both SRY-positive and SRY-negative streak gonads. Although the SRY gene has a very important role in testicular differentiation, genes other than the SRY gene might also influence the development of the indifferent gonad in MGD.

Case-Control Studies↗
PubMed1995

Bovine SRY gene locus: cloning and testicular expression.

The bovine SRY gene was cloned by a combination of anchored polymerase chain reaction (PCR) amplification of genomic restriction fragments and reverse transcription-PCR (RT-PCR) of testicular RNA. We report 1800 bp of combined genomic and cDNA sequences including 911 bp of 5' upstream sequences, an open reading frame of 687 bp, and 202 bp of sequences corresponding to the 3' end of the mRNA. The bovine SRY gene encodes a deduced (predicted on the basis of a cDNA sequence) protein product of 229 amino acids, with sequence conservation between species, notably in the region of the high-mobility group (HMG) domain or HMG box. Outside of the HMG box, the bovine SRY structure shows greater resemblance to the human SRY than to the mouse Sry. As with human SRY promoter sequences, putative binding sites for Sp1 and for SRY itself are seen in the bovine SRY promoter region. Unlike the human SRY promoter, CAAT and TATA box motifs are present in the bovine sequences. Southern analysis and PCR amplification of male and female bovine genomic DNA show that the described sequences are specific to the Y chromosome. Northern analysis of bull testicular RNA demonstrated low levels of expression of the bovine SRY gene in adult testes with a major poly(A) species at 1.9 kb. RT-PCR amplification of bull testicular RNA revealed multiple sites of polyadenylation, but sequencing showed no consensus polyadenylation signal.

Amino Acid Sequence↗
PubMedDate not supplied

Characterization of Bovidae sex-determining gene SRY.

In mammals, testis determination is under the control of the sex-determining gene SRY. This Y-linked gene encodes a protein with a DNA binding domain similar to those found in high-mobility-group proteins. Here we report the cloning and sequences of the SRY genes of yak and Chinese native cattle. Our data show that SRY genes in Bovidae are less divergent, especially in the coding and 3' regions.

3' Untranslated Regions↗
PubMed2004

Analysis of SRY gene in 8 cases of sex abnormality.

In order to investigate the relationship between sex dysplasia and sex-determining region Y (SRY) gene, 8 patients with sexual abnormality were analyzed by cytogenetic and molecular genetic methods. Fluorescence in situ hybridization (FISH) using PY3.4, X alpha satellite, and SRY probes was performed in each case to analyze the sex chromosome translocation and gene translocation. SRY gene was amplified by polymerase chain reaction (PCR) and its mutation was detected by direct sequencing. The results showed that among 8 patients, 5 were positive for SRY and the remaining negative for SRY. In the patients positive for SRY genes, 3 presented testes and the left 2 streak ovaries. In the patients negative for SRY, only one case presented testes, while 2 ovaries. Direct sequencing demonstrated that all SRY genes were normal in the patients positive for SRY genes. FISH technique demonstrated that SRY genes translocated from Ypter to Xpter in 2 46,XX phenotypic males positive for SRY genes. It was concluded that SRY gene is strongly involved in male sex determination, while a sequence of other genes may be taken into account in sexual development.

Female↗
PubMed2003

[Cloning and sequencing of Sry gene of muntiacus].

Using the primers from SRY gene--HMG Box for PCR amplification in genomic DNA of Muntiacus reevesi cell strains, a 220bp fragment was obtained in the male but not in the female. The 220bp fragment was cloned into the pGEM-T vector using T/A clone method. The identified positive clone was sequenced. The result shows that 82.6% nucleotides(152bp/184bp) are homologous between Muntiacus Sry and human SRY gene. It suggests that SRY is highly conserved during evolution.

English Abstract↗
PubMed1993

A new de novo mutation (A113T) in HMG box of the SRY gene leads to XY gonadal dysgenesis.

We describe a new point mutation in the SRY gene of a Chinese XY female with gonadal dysgenesis (Swyer syndrome). Using the double stranded DNA cycle sequencing method, a single nucleotide substitution of G-->A was identified at codon 113 of the patient's SRY gene, resulting in a conservative amino acid change from alanine (A) to threonine (T) at a residue that lies within the putative DNA binding motif. With this mutation, one MnlI recognition site is abolished and a new BsmAI site is present in the DNA sequence of the SRY gene; therefore, it is easily detected by analysis of the digestion of the amplified SRY DNA fragment on an electrophoretic agarose gel. In situ hybridisation to the XY female's chromosomes showed that her mutant SRY gene was indeed located on the short arm of her Y chromosome. The SRY mutation in the XY female reported here occurred de novo, as sequence analysis showed that it was not present in her father or other family members.

Adult↗
PubMed2006

Tandem duplication and copy number polymorphism of the SRY gene in patients with sex chromosome anomalies and males exposed to natural background radiation.

Mutations in the SRY gene encompassing the HMG box have been well characterized in gonadal dysgenesis, male infertility and other types of sex chromosome related anomalies (SCRA). However, no information is available on copy number status of this gene under such abnormal conditions. Employing 'Taqman Probe Assay' specific to the SRY gene, we screened 16 DNA samples from patients with SCRA and 36 samples from males exposed to high levels of natural background radiation (HNBR). Patients with SCRA showed 2-16 copies of the SRY gene of which, one, Oxen (49, XYYYY) had eight copies with sequences different from one another. Of the 36 HNBR samples, 12 had one copy whereas 24 harboured 2-8 copies of the SRY gene. A HNBR male 33F had one normal and one mutated copy of this gene. Analysis of 25 DNA samples from blood and semen of normal males showed only one copy of this gene. Despite multiple copies in affected males, fluorescence in-situ hybridization (FISH) with SRY probe detected a single signal on the Y chromosome in HNBR males suggesting its possible localized tandem duplication. Copy number status of the other Y-linked loci is envisaged to augment DNA diagnostics facilitating genetic counselling to affected patients.

Amino Acid Sequence↗
PubMed1998

Identification of conserved potentially regulatory sequences of the SRY gene from 10 different species of mammals.

We have sequenced the 5' region of the SRY gene from human, chimpanzee, sheep, and mouse and from four additional mammalian species, not previously characterized (gorilla, gazelle, rat, and guinea pig). In order to identify conserved DNA elements potentially involved in the regulation of the SRY gene, the newly determined sequences were analyzed and compared to all mammalian SRY promoter sequences available at present. Ten highly conserved potential regulatory elements have been identified in all 10 species (AP1, Barbie, GATA, Gfi1, cMyb, vMyb, NF1, Oct1, Sp1, and SRY). The known function of several of these regulatory elements fits well with the known expression of the SRY gene. However, except for the highly conserved coding HMG motif, only a short region close to the initiation of transcription in the human SRY is conserved in the exact position along the gene in all the species analyzed. This lack of sequence identity at the orthologous positions is consistent with the suggested rapid evolution of the SRY gene. This relative lack of homology contrasts with a high sequence identity of the putative regulatory sequences found within each taxonomic group of species (primates, bovids, and rodents), which supports a common mechanism of SRY expression and possibly also a similar function.

Amino Acid Sequence↗
PubMed1996

Porcine SRY gene locus and genital ridge expression.

Porcine SRY gene locus was cloned through use of a strategy of anchored polymerase chain reaction (PCR) amplification from a male pig genomic DNA size-selected library constructed in a plasmid vector as well as 3' reverse transcription (RT)-PCR amplification of porcine genital ridge SRY transcripts. In total, 1664 bp of genomic DNA and 106 bp of 3' cDNA are presented. The open reading frame of porcine SRY consists of 624 bp representing 208 amino acids (aa) with a centrally located HMG box domain of 79 aa, an amino-terminal region of 59 aa, and a carboxy terminal of 70 aa. Structurally, porcine SRY resembles human and bovine SRY more closely than it does mouse Sry, and it lacks the carboxy-terminal activation domain seen in the mouse Sry molecule. Similar to human and bovine testicular SRY transcripts, the porcine SRY genital ridge transcript has a relatively short 3' untranslated region (UTR), in contrast to the extended UTR of the mouse genital ridge Sry transcript. The porcine SRY gene is expressed within the cells of the genital ridge of the developing male pig embryo between Days 21 and 26 (e21-e26) of gestation, during which time the primitive gonads are bipotential, but not on Day e31, by which time male testis determination is histologically evident.

Amino Acid Sequence↗
PubMed2005

Three new novel point mutations localized within and downstream of high-mobility group-box region in SRY gene in three Indian females with Turner syndrome.

Point mutations and deletions in the SRY gene result in XY sex reversal in pure gonadal dysgenesis. To date, a majority of these affect the high-mobility group (HMG) domain of SRY, which plays a key role in its DNA binding activity. We carried out molecular genetics studies in three Turner syndrome patients all presenting with 45,X/46,XY mosaic karyotype. Case 1 demonstrated an insertion of T (thymine) within helix I of HMG box leading to frame shift mutation (N82X). In case 2, insertion of A (adenine) downstream of HMG box resulted in a nonsense frame shift mutation (L159fsX167). These mutations resulted in truncated and altered proteins. In case 3, G>C missense mutation is found at codon 74 within helix I of HMG box (Q74H). No other mutations were found in the SRY gene of these patients. An allele-specific oligonucleotide study further confirmed that these variants are not common polymorphisms. To our knowledge, this is the first time these mutations are described at these codons resulting in mutated SRY proteins. Lack of a second sex chromosome in a majority of cells [mosaic karyotype and mutation(s) in the SRY gene] in these patients may have triggered the short stature.

Adult↗
PubMed1993

Rapid sequence evolution of the mammalian sex-determining gene SRY.

In mammals, induction of male sex determination requires the Y-chromosome gene SRY. SRY encodes a protein with a central 'high mobility group' domain (HMG box) of about 78 amino acids. HMG boxes are found in a wide variety of proteins that bind to DNA with high affinity but differing degrees of sequence specificity. The human SRY protein binds to linear DNA with sequence specificity and to cruciform DNA structures without sequence specificity. The DNA-binding activity of the SRY protein resides in the HMG box and mutations in this region are associated with sex reversal in XY females. No function has been ascribed to the portions of the SRY protein outside the HMG box. SRY belongs to a family of genes that are related by sequence homology within the DNA-binding domain: the genes most similar to SRY (> 60%) have been named SOX genes (SRY box genes). None of the known SOX genes is homologous to SRY outside the HMG-box region. Although SRY is an important developmental regulator, its sequence is poorly conserved between species apart from the HMG-box domain. Here we investigate the coding sequence of SRY in primates and find that evolution has been rapid in the regions flanking the conserved domain. The high degree of sequence divergence and the frequency of non-synonymous mutations suggest either that the majority of the coding sequence has no functional significance or that directional selection has occurred.

Amino Acid Sequence↗
PubMed2000

A novel missense mutation in the HMG box region of the SRY gene in a Japanese patient with an XY sex reversal.

The sex-determining region of the Y chromosome, the SRY gene, located on the short arm of the Y chromosome, is appreciated as one of the genes that is responsible for directing the process of sex differentiation. To date, 34 different mutations, including 29 missense and nonsense mutations in the SRY gene, have been described in XY female patients. We investigated the molecular basis of the sex reversal in one Japanese XY female patient by determining the nucleotide sequence of the SRY gene, using polymerase chain reaction and direct sequencing. We identified a novel mutation, of the substitution of Tyr for Asn at nucleotide position 87 (N87Y). This Asn residue is located within the DNA-binding high-mobility-group (HMG) motif, which is considered to be the main functional domain of the SRY protein. Further, this amino acid, Asn, is a conserved residue among mammalian SRY genes. These findings indicate that this amino acid substitution may be responsible for the sex reversal in this patient.

Amino Acid Substitution↗