Ontogeny and cellular localization of SRY transcripts in the human testes and its detection in spermatozoa

Optimized total RNA isolation from bovine sperm with enhanced sperm head lysis

Increasing evidence of sperm RNA's role in fertilization and embryonic development has provided impetus for its isolation and thorough characterization. Sperm are considered tough-to-lyse cells due to the compact condensed DNA in sperm heads. Lack of consensus among bovine sperm RNA isolation protocols introduces experimental variability in transcriptome studies. Here, we describe an optimized method for total RNA isolation from bovine sperm using the TRIzol reagent. This study critically investigated the effects of various lysis conditions on sperm RNA isolation. Sperm suspended in TRIzol were subjected to a combination of mechanical treatments (sonication and passage through a 30G needle and syringe) and chemical treatments (supplementation with reducing agents 1,4-dithiothreitol and tris(2-carboxyethyl) phosphine hydrochloride (TCEP)). Microscopic evaluation of sperm lysis confirmed preferential sperm tail versus sperm head lysis. Interestingly, only TCEP-supplemented TRIzol (both mechanical treatments) had progressive sperm head lysis and consistently yielded total sperm RNA. Furthermore, RNA integrity was confirmed based on the electrophoresis profile and an absence of genomic DNA and somatic cells (e.g., epithelial cells, spermatids, etc.) with RT-qPCR. Our findings highlighted the importance of sperm lysis, specifically of the sperm head using TCEP with mechanical treatment, in total RNA isolation and presented a bovine-specific sperm RNA isolation method to reduce experimental variabilities.

Molecular and Functional Characterization of Human Sex-Determining Region on the Y Chromosome Variants Using Protamine 1 Promoter

The male sex-determining gene, sex-determining region on the Y chromosome (SRY), is expressed in adult testicular germ cells; however, its role in regulating spermatogenesis remains unclear. The role of SRY in the postmeiotic gene expression was investigated by determining the effect of SRY on the promoter of the haploid-specific Protamine 1 (PRM1) gene, which harbors five distinct SRY-binding motifs. In a luciferase reporter assay system, SRY upregulates PRM1 promoter activity in vitro in a dose-dependent manner. Through a gel-shift assay involving a 31-bp DNA fragment encompassing the SRY element within the PRM1 promoter, the third SRY-binding site on the sense strand (-373/-367) was identified as crucial for PRM1 promoter activation. This assay was extended to analyze 9 SRY variants found in the testicular DNA of 44 azoospermia patients. The findings suggest that SRY regulates PRM1 promoter activity by directly binding to its specific motif within the PRM1 promoter.

Azoospermia factor c microdeletions and outcomes of assisted reproductive technology: a systematic review and meta-analysis

OBJECTIVE

To investigate whether Azoospermia Factor c (AZFc) microdeletions affect Assisted Reproductive Technology (ART) outcomes.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENTS

Infertile men with and without AZFc microdeletions.

INTERVENTION(S)

Electronic databases were searched for case-control studies reporting sperm retrieval rates and outcomes of ART in infertile men with and without AZFc microdeletions from inception to April 2023. Study quality was assessed using the Newcastle-Ottawa Scale. Summary effect sizes (odds ratio [OR] with 95% confidence interval [CI]) were calculated for both categories of infertile men.

MAIN OUTCOME MEASURES

The primary outcome was successful sperm retrieval and the secondary outcomes were outcomes of ART.

RESULTS

Case-control studies reporting sperm retrieval rates and ART outcomes in men with AZFa and AZFb deletions were unavailable. On the basis of the data from 3,807 men, sperm retrieval rates were found to be higher in men with AZFc microdeletions compared to their non-deleted counterparts [OR = 1.82, 95% CI 0.97, 3.41], but the difference was not statistically significant. A significantly lower fertilization rate (OR = 0.61, 95% CI [0.50, 0.74]), clinical pregnancy rate (OR = 0.61, 95% CI [0.42, 0.89]), and live birth rate (OR = 0.54, 95% CI [0.40, 0.72]) were observed in men with AZFc deletions compared with men without deletions. There was no statistically significant difference in rates of embryo cleavage, blastocyst formation, good-quality embryos, implantation, and miscarriage between the two groups. On correcting for female factors, the fertilization rate (OR = 0.76, 95% CI [0.71, 0.82]), cleavage rate (OR = 0.54, 95% CI [0.41, 0.72]), clinical pregnancy rate (OR = 0.39, 95% CI [0.30, 0.52]), and live birth rate (OR = 0.48, 95% CI [0.35, 0.65]) were significantly lower in men with AZFc deletions compared with controls.

CONCLUSIONS

Presence of AZFc microdeletions adversely affects outcomes of ART in infertile men. Further in-depth studies delineating the role of the AZF genes in embryonic development are necessary to understand the full-impact of this finding.

CLINICAL TRIAL REGISTRATION NUMBER

CRD42022311738.

Modeling Human Gonad Development in Organoids

BACKGROUND

Our learning about human reproductive development is greatly hampered due to the absence of an adequate model. Animal studies cannot truthfully recapitulate human developmental processes, and studies of human fetal tissues are limited by their availability and ethical restrictions. Innovative three-dimensional (3D) organoid technology utilizing human pluripotent stem cells (hPSCs) offered a new approach to study tissue and organ development in vitro. However, a system for modeling human gonad development has not been established, thus, limiting our ability to study causes of infertility.

METHODS

In our study we utilized the 3D hPSC organoid culture in mini-spin bioreactors. Relying on intrinsic self-organizing and differentiation capabilities of stem cells, we explored whether organoids could mimic the development of human embryonic and fetal gonad.

RESULTS

We have developed a simple, bioreactor-based organoid system for modeling early human gonad development. Male hPSC-derived organoids follow the embryonic gonad developmental trajectory and differentiate into multipotent progenitors, which further specialize into testicular supporting and interstitial cells. We demonstrated functional activity of the generated cell types by analyzing the expression of cell type-specific markers. Furthermore, the specification of gonadal progenitors in organoid culture was accompanied by the characteristic architectural tissue organization.

CONCLUSION

This organoid system opens the opportunity for detailed studies of human gonad and germ cell development that can advance our understanding of sex development disorders. Implementation of human gonad organoid technology could be extended to modeling causes of infertility and regenerative medicine applications.

Two Short Repeats in the 5′ Untranslated Region of Insulin-like Androgenic Gland Factor in Procambarus clarkii (PcIAG) That Regulate PcIAG Expression

Insulin-like androgenic gland factor (IAG) plays an important role in sex manipulation in decapods. Understanding the molecular regulation mechanism of IAG in Procambarus clarkii (PcIAG) is important for realizing its sex control. In this study, the promoter and gene structure of PcIAG, mRNA, and miRNA expression profiles after interfering with two siRNAs synthesized according to the two short repeats in the 5′ untranslated regions (5′UTR) of PcIAG were analyzed, and miRNAs of exosomes were investigated to explore the role of repeated sequences with tandem two short repeats located in the 5′UTR of PcIAG isolated from the androgenic gland (AG) in the regulation of IAG expression. The results showed that the repeated sequences of 5′UTR only occurred completely in the cDNA from AG, and the function of the two repeats was different in regulating the expression of PcIAG, in which the Wnt signaling pathway may be involved. Furthermore, we found that six miRNAs including miR-133, miR-193, miR-34, miR-1, miR-100, and let-7 might be involved in the regulation of the expression of PcIAG, wherein miR-133 might directly be related with the repeated sequences of 5′UTR.

Further Insights on RNA Expression and Sperm Motility

Asthenozoospermia is one of the main causes of male infertility and it is characterized by reduced sperm motility. Several mutations in genes that code for structural or functional constituents of the sperm have already been identified as known causes of asthenozoospermia. In contrast, the role of sperm RNA in regulating sperm motility is still not fully understood. Consequently, here we aim to contribute to the knowledge regarding the expression of sperm RNA, and ultimately, to provide further insights into its relationship with sperm motility. We investigated the expression of a group of mRNAs by using real-time PCR (CATSPER3, CFAP44, CRHR1, HIP1, IQCG KRT34, LRRC6, QRICH2, RSPH6A, SPATA33 and TEKT2) and the highest score corresponding to the target miRNA for each mRNA in asthenozoospermic and normozoospermic individuals. We observed a reduced expression of all mRNAs and miRNAs in asthenozoospermic patients compared to controls, with a more accentuated reduction in patients with progressive sperm motility lower than 15%. Our work provides further insights regarding the role of RNA in regulating sperm motility. Further studies are required to determine how these genes and their corresponding miRNA act regarding sperm motility, particularly KRT34 and CRHR1, which have not previously been seen to play a significant role in regulating sperm motility.

The RNA content of human sperm reflects prior events in spermatogenesis and potential post-fertilization effects

Transcriptome analyses using high-throughput methodologies allow a deeper understanding of biological functions in different cell types/tissues. The present study provides an RNA-seq profiling of human sperm mRNAs and lncRNAs (messenger and long non-coding RNAs) in a well-characterized population of fertile individuals. Sperm RNA was extracted from twelve ejaculate samples under strict quality controls. Poly(A)-transcripts were sequenced and aligned to the human genome. mRNAs and lncRNAs were classified according to their mean expression values (FPKM: Fragments Per Kilobase of transcript per Million mapped reads) and integrity. Gene Ontology analysis of the Expressed and Highly Expressed mRNAs showed an involvement in diverse reproduction processes, while the Ubiquitously Expressed and Highly Stable mRNAs were mainly involved in spermatogenesis. Transcription factor enrichment analyses revealed that the Highly Expressed and Ubiquitously Expressed sperm mRNAs were primarily regulated by zinc-fingers and spermatogenesis-related proteins. Regarding the Expressed lncRNAs, only one-third of their potential targets corresponded to Expressed mRNAs and were enriched in cell-cycle regulation processes. The remaining two-thirds were absent in sperm and were enriched in embryogenesis-related processes. A significant amount of post-testicular sperm mRNAs and lncRNAs was also detected. Even though our study is solely directed to the poly-A fraction of sperm transcripts, results indicate that both sperm mRNAs and lncRNAs constitute a footprint of previous spermatogenesis events and are configured to affect the first stages of embryo development.

Nigral and ventral tegmental area lesioning induces testicular and sperm morphological abnormalities in a rotenone model of Parkinson's disease

Although sexual health is affected by Parkinson's disease (PD), the effect on testicular health and/or sperm quality is not well discussed. After 21 days of rotenone lesioning, we observed dopaminergic neuronal degeneration in the substantia nigra and hypothalamus. There were minimal SPACA-1-expressing epididymal spermatozoa with morphological abnormalities, scanty luminal spermatozoa and reduced testicular spermatids and post-meiotic germ cells indicating hypospermatogenesis. Occludin-expressing sertoli cells were dispersed over a wide area indicating compromised blood-testes barrier. Activated caspase-3 expression was intense while immunoreactivity of spermatogenic-enhancing SRY and GADD45 g was weak. Although serum follicle stimulating hormone level was not affected, the lesion was associated with reduced serum testosterone level, testicular oxidative damage and inhibition of acetylcholinesterase activity, even when rotenone was not detected in the testes. Together, dopaminergic lesions may mediate testicular and sperm abnormalities via the brain-hypothalamic-testicular circuit independent of the pituitary, thereby establishing a causal link between Parkinsonism and reproductive dysfunction.

Regulation of CATSPER1 expression by the testis-determining gene SRY

CATSPER1 gene encodes a pore-forming and pH-sensing subunit of the CatSper Ca²⁺- permeable channel, a protein in the flagellum essential for sperm hyperactivation. Previous studies have shown that the murine Catsper1 gene promoter is regulated by different Sox proteins. Likewise, it is acknowledged that the human CATSPER1 gene promoter sequence is enriched in potential interaction sites for the sex-determining region Y gene (SRY), which suggest a novel regulatory transcriptional mechanism for CatSper1 channel expression. Therefore, in this work, we sought to determine whether the human CATSPER1 gene expression is regulated by the SRY transcription factor. To this end, a series of deletions and mutations were introduced in the wild- type CATSPER1 gene promoter to eliminate the SRY sites, and the different constructs were tested for their ability to activate transcription in human embryonic kidney and murine spermatogonial germ cell lines (HEK-293 and GC1-spg, respectively) using luciferase assays. In addition, by using a strategy that combines electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) we investigated whether the CATSPER1 gene expression is regulated by the SRY transcription factor both in vitro and in vivo. Our results show that the transcriptional factor SRY specifically binds to different sites in the promoter sequence and has the ability to control CATSPER1 gene transcription.

Genetics of the human Y chromosome and its association with male infertility

The human Y chromosome harbors genes that are responsible for testis development and also for initiation and maintenance of spermatogenesis in adulthood. The long arm of the Y chromosome (Yq) contains many ampliconic and palindromic sequences making it predisposed to self-recombination during spermatogenesis and hence susceptible to intra-chromosomal deletions. Such deletions lead to copy number variation in genes of the Y chromosome resulting in male infertility. Three common Yq deletions that recur in infertile males are termed as AZF (Azoospermia Factor) microdeletions viz. AZFa, AZFb and AZFc. As estimated from data of nearly 40,000 Y chromosomes, the global prevalence of Yq microdeletions is 7.5% in infertile males; however the European infertile men are less susceptible to Yq microdeletions, the highest prevalence is in Americans and East Asian infertile men. In addition, partial deletions of the AZFc locus have been associated with infertility but the effect seems to be ethnicity dependent. Analysis of > 17,000 Y chromosomes from fertile and infertile men has revealed an association of gr/gr deletion with male infertility in Caucasians and Mongolian men, while the b2/b3 deletion is associated with male infertility in African and Dravidian men. Clinically, the screening for Yq microdeletions would aid the clinician in determining the cause of male infertility and decide a rational management strategy for the patient. As these deletions are transmitted to 100% of male offspring born through assisted reproduction, testing of Yq deletions will allow the couples to make an informed choice regarding the perpetuation of male infertility in future generations. With the emerging data on association of Yq deletions with testicular cancers and neuropsychiatric conditions long term follow-up data is urgently needed for infertile men harboring Yq deletions. If found so, the information will change the current the perspective of androgenetics from infertility and might have broad implication in men health.

Expression profiles of Sox transcription factors within the postnatal rodent testes

SRY-related box (Sox) transcription factors are conserved among vertebrate species. These proteins regulate multiple processes including sex determination and testis differentiation of the male embryo. Members of the Sox family have been identified in pre- and postnatal testis and are known to play an important role in sex determination (Sry, Sox9), male gonadal development, and fertility (Sox4, Sox8, Sox30). However, their expression profiles per cell types remain elusive. The objectives of this research were to characterize the expression profiles of Sox family members within adult testes using publically available datasets and to determine whether these findings are consistent with literature as well as immunofluorescence and in situ hybridization results. We have found that Sox4, Sox8, Sox9, and Sox12 are highly expressed in Sertoli cells, whereas Sox5, Sox6, and Sox30 were typically expressed in spermatocytes and spermatids. Spermatogonia were characterized by the expressions of Sox3, Sox4, Sox12, Sox13, and Sox18. Hence, these results suggest that Sox transcription factors may play different roles according to cell types of the adult mammalian testis.

The bovine sex-determining region Y (Sry) gene and its mRNA transcript are present in Y sperm but not X sperm of bulls

The aims of this study were to establish whether the sex-determining region Y gene and its mRNA transcript are present in the Y sperm and X sperm of bulls and, if present, determine their cellular localization. Semen was collected from three bulls and sorted by flow cytometry into X- and Y-chromosome populations. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine Sry mRNA expression in X sperm and Y sperm. The presence and localization of Sry DNA and RNA were investigated by fluorescence in situ hybridization (FISH). RT-PCR detected a single Sry transcript of 142 bp in Y sperm but not in X sperm. In Y sperm, the FISH-positive rates for Sry DNA and Sry RNA did not differ significantly from the re-analyzed Y sperm purity. In further experiments, there were no significant differences between the FISH-positive rate for Sry RNA and the re-analyzed Y sperm purity for X-sorted, Y-sorted, or unsorted sperm. In conclusion, FISH analysis revealed that Sry transcripts are present at the edges of the sperm heads of Y sperm but are absent from X sperm.

Sperm-carried RNAs play critical roles in mouse embryonic development

Recently, numerous studies have reported that the mature sperm contains both coding and non-coding RNAs and the sperm delivers some RNAs to the oocyte at fertilization. However, the functions of the RNAs carried to the oocyte by sperm at fertilization in embryonic development remains a mystery. In this study, the mature spermatozoa were treated with lysolecithin, pronase and RNases (RNase A and RNase H) to remove the sperm-carried RNAs, and then injected into normal mature oocyte. The results showed that after the treatment, the content of the sperm RNAs was decreased by about 90%. The blastocyst formation rate and the live birth rate of the embryos from intracytoplasmic sperm injection (ICSI) using the treated sperm were significantly decreased (P<0.01), while these effects were partially rescued by injecting total wide-type sperm RNAs. The reproductive capacity of offspring (F0) in sperm-treated group was similar with that in control group (P>0.05), but the body weight of F1 mice from sperm-treated group was lower than that in control group after two weeks of birth (P<0.05). These results demonstrated that the sperm-carried RNAs have important roles in embryonic development.

Bioimaging of microRNA34c in a single sperm using a molecular beacon

The VisuFect-conjugated molecular beacon was developed for non-invasive visualization of microRNA34c in a living single mouse sperm.

Chromatin and extracellular vesicle associated sperm RNAs

A diverse pool of RNAs remain encapsulated within the transcriptionally silent spermatozoon despite the dramatic reduction in cellular and nuclear volume following cytoplasm/nucleoplasm expulsion. The impact of this pronounced restructuring on the distribution of transcripts inside the sperm essentially remains unknown. To define their compartmentalization, total RNA >100 nt was extracted from sonicated (SS) mouse spermatozoa and detergent demembranated sucrose gradient fractionated (Cs/Tx) sperm heads. Sperm RNAs predominately localized toward the periphery. The corresponding distribution of transcripts and thus localization and complexity were then inferred by RNA-seq. Interestingly, the number of annotated RNAs in the CsTx sperm heads exhibiting reduced peripheral enrichment was restricted. However this included Cabyr, the calcium-binding tyrosine phosphorylation-regulated protein encoded transcript. It is present in murine zygotes prior to the maternal to the zygotic transition yet absent in oocytes, consistent with the delivery of internally positioned sperm-borne RNAs to the embryo. In comparison, transcripts enriched in sonicated sperm contributed to the mitochondria and exosomes along with several nuclear transcripts including the metastasis associated lung adenocarcinoma transcript 1 (Malat1) and several small nucleolar RNAs. Their preferential peripheral localization suggests that chromatin remodeling during spermiogenesis is not limited to nucleoproteins as part of the nucleoprotein exchange.

Identification of X monosomy cells from a gonad of mixed gonadal dysgenesis with a 46,XY karyotype: case report

Mixed gonadal dysgenesis (MGD) is a disorder of sexual development that typically has a mosaic 45,X/46,XY karyotype. A 1-year-old infant with 46,XY identified by peripheral blood karyotype demonstrated clinical manifestations and gonadal pathologic features of MGD. Fluorescence in situ hybridization (FISH) for X and Y chromosomes and immunofluorescence for SRY along with testicular and ovarian lineage markers SOX9 and FOXL2, respectively, were performed on paraffin sections from the gonad to ascertain the somatic mosaic state for 45,X monosomy and 46,XY cells. The gonad consisted of cells with X and XY signals, which were further quantified in comparison with a normal control testis by a digital image analysis program. The average percentages of 45,X cells of this patient's gonad and a control testis were 39.0% and 5.7%, respectively (χ2 test, P < 0.001). SRY expression was absent in approximately 10% of precursor granulosa cells (FOXL2 positive) and precursor Sertoli/granulosa cells (both SOX9 and FOXL2 positive) within gonadoblastomas, confirming the involvement of 45,X cells. A combination of analysis of FISH and immunofluorescence for SRY in the gonadal tissue could identify 45,X cells in MGD with 46,XY.

Cellular ontogeny of RBMY during human spermatogenesis and its role in sperm motility

The Y-chromosome-encoded gene RBMY (RNA-binding motif on Y) is a male germline RNA-binding protein and is postulated to be a RNA-splicing regulator. In order to understand the roles of RBMY in different stages of male gamete maturation, the present study aimed at determining its cellular expression during spermatogenesis, spermeogenesis and in mature spermatozoa. In the spermatogonia (cKIT-positive cells), RBMY immunolocalized as two distinct foci, one in the nucleolus and the other in the subnuclear region; in the spermatocytes (cKIT-negative cells), the nucleus had punctuate staining with a subnuclear foci; in the pachytene cells, the protein was localized as a punctuate pattern in the nucleus spread along the elongating chromosomes. In the round and the elongating spermatids, the protein expression was polarized and restricted to the cytoplasm and in the developing mid-piece. In testicular and ejaculated sperm, RBMY was localized to the mid-piece region and weakly in the tail. Incubation of spermatozoa with the RBMY antibody reduced its motility. The spatial differences in expression of RBMY in the germ cells and the presences of this protein in post-meiotic cells and in transcriptionally inert spermatozoa suggest its involvement in multiple functions beyond RNA splicing. One such possible function of RBMY could be its involvement in sperm motility.

Absolute copy number differences of Y chromosomal genes between crossbred (Bos taurus × Bos indicus) and Indicine bulls

Background

The Y chromosome in mammal is paternally inherited and harbors genes related to male fertility and spermatogenesis. The unique intra-chromosomal recombination pattern of Y chromosome and morphological difference of this chromosome between Bos taurus and Bos indicus make it an ideal model for studying structural variation, especially in crossbred (Bos taurus × Bos indicus) bulls. Copy Number Variation (CNV) is a type of genomic structural variation that gives information complementary to SNP data. The purpose of this study was to find out copy number differences of four Y chromosomal spermatogenesis-related candidate genes in genomic DNA of crossbred and purebred Indicine bulls.

Result

Four Y chromosomal candidate genes of spermatogenesis namely, sex determining gene on Y chromosome (SRY), DEAD box polypeptide 3-Y chromosome (DDX3Y), Ubiquitin specific peptidase 9, Y-linked (USP9Y), testis-specific protein on Y chromosome (TSPY) were evaluated. Absolute copy numbers of Y chromosomal genes were determined by standard curve-based quantitative real time PCR. Copy numbers of SRY and TSPY genes per unit amount of genomic DNA are higher in crossbred than Indicine bulls. However, no difference was observed in DDX3Y and USP9Y gene copy numbers between two groups.

Conclusion

The present study demonstrates that the structural organization of Y chromosomes differs between crossbred and Indicine bulls which are reproductively healthy as observed from analysis of semen attributes. The absolute copy numbers of SRY and TSPY genes in unit mass of genomic DNA of crossbred bulls are significantly higher than Indicine bulls. No alteration in absolute copies of DDX3Y and USP9Y gene was found between the genome of crossbred and Indicine bulls. This study suggests that the DDX3Y and USP9Y are likely to be single copy genes in the genome of crossbred and Indicine bulls and variation in Y chromosome length between crossbred and Indicine bulls may be due to the copy number variation of SRY gene and TSPY array.

Identification of a new mouse sperm acrosome-associated protein

The binding of capacitated spermatozoa to the egg's extracellular coat and induction of acrosome reaction are necessary for successful fertilization in mammals. Biogenesis of acrosome is complicated, and not all proteins involved in this process are known. In this study, we have cloned a novel mouse gene, Spaca7, that is expressed exclusively in the testes. During the postnatal development, transcripts of the gene could be detected at a very low level in 18-day-old mouse testes and at a higher level in 21-day-old mouse testes and later, which corresponds to an expansion of round spermatids. In the stably transfected PT67 cells, SPACA7 fused with EGFP was predominantly localized in the Golgi apparatus. In transgenic mouse testes, the fusion protein was found in acrosome (starting from the first stages of acrosome formation in late pachytene spermatocytes and finally in spermatozoa isolated from caput and cauda of epididymis). Confocal microscopy studies revealed an intra-acrosomal not membrane-bound localization of SPACA7/EGFP, which suggests that the protein can be released during acrosome reaction and involved in fertilization. Acrosomal localization of endogenous SPACA7 protein was also found in human spermatozoa.

Gene transcripts in spermatozoa: markers of male infertility

The presence of a complex population of gene transcripts in mature human sperm is well established, and numerous mRNAs and non-coding mRNAs have been identified in sperm of men and other mammalian species using microarray and RT-PCR. The traditional concept that RNAs in mature sperm are only remnants from spermatogenesis and have no biological functions is in doubt. The findings that reverse transcriptases in sperm are active and that sperm can independently activate translation of stored mRNAs suggest that sperm RNAs may have significant effects on male fertility. The differences in expression profiles among RNAs in mature sperm from fertile and infertile men, and the regulation of sperm RNAs in embryonic development make them appealing markers for therapeutic and diagnostic tools in male infertility. In this review, methods for the detection and description of the diversity of gene transcript in sperm are discussed along with their putative roles in functional aspects of sperm and in embryogenesis.

Human spermatozoal RNAs

OBJECTIVE

To provide a focused review of the scientific literature pertaining to spermatozoal RNA.

DESIGN

Review of the literature and appraisal of relevant articles.

SETTING

Not applicable.

PATIENT(S)

Infertile male.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Spermatozoal RNAs as potential epigenetic modifiers in early embryo development and as clinical markers of male infertility.

RESULT(S)

The nucleus of mature spermatozoa contains a complex population of mRNAs and miRNAs despite its transcriptionally inert state.

CONCLUSION(S)

A specific set of functional RNAs are delivered into oocytes during fertilization and are thought to contribute extragenomically to early embryonic development. Even if spermatozoal RNAs is merely residual, it still has the potential to greatly improve the investigative and diagnostic potential of male infertility.

Sry, more than testis determination?

The Sry locus on the mammalian Y chromosome is the developmental switch responsible for testis determination. Inconsistent with this important function, the Sry locus is transcribed in adult males at times and in tissues not involved with testis determination. Sry is expressed in multiple tissues of the peripheral and central nervous system. Sry is derived from Sox3 and is similar to other SOXB family loci. The SOXB loci are responsible for nervous system development. Sry has been demonstrated to modulate the catecholamine pathway, so it should have functional consequences in the central and peripheral nervous system. The nervous system expression and potential function are consistent with Sry as a SOXB family member. In mammals, Sox3 is X-linked and undergoes dosage compensation in females. The expression of Sry in adult males allows for a type of sexual differentiation independent of circulating gonadal hormones. A quantitative difference in Sox3 plus Sry expression in males vs. females could drive changes in the transcriptome of these cells, differentiating male and female cells. Sry expression and its transcriptional effects should be considered when investigating sexual dimorphic phenotypes.

Epigenetic abnormality of SRY gene in the adult XY female with pericentric inversion of the Y chromosome

In normal ontogenetic development, the expression of the sex-determining region of the Y chromosome (SRY) gene, involved in the first step of male sex differentiation, is spatiotemporally regulated in an elaborate fashion. SRY is expressed in germ cells and Sertoli cells in adult testes. However, only few reports have focused on the expressions of SRY and the other sex-determining genes in both the classical organ developing through these genes (gonad) and the peripheral tissue (skin) of adult XY females. In this study, we examined the gonadal tissue and fibroblasts of a 17-year-old woman suspected of having disorders of sexual differentiation by cytogenetic, histological, and molecular analyses. The patient was found to have the 46,X,inv(Y)(p11.2q11.2) karyotype and streak gonads with abnormally prolonged SRY expression. The sex-determining gene expressions in the patient-derived fibroblasts were significantly changed relative to those from a normal male. Further, the acetylated histone H3 levels in the SRY region were significantly high relative to those of the normal male. As SRY is epistatic in the sex-determination pathway, the prolonged SRY expression possibly induced a destabilizing effect on the expressions of the downstream sex-determining genes. Collectively, alterations in the sex-determining gene expressions persisted in association with disorders of sexual differentiation not only in the streak gonads but also in the skin of the patient. The findings suggest that correct regulation of SRY expression is crucial for normal male sex differentiation, even if SRY is translated normally.

Spermatozoal RNAs: what about their functions?

The profound architectural changes that transform spermatids into spermatozoa result in a high degree of DNA packaging within the sperm head. However, the mature sperm chromatin that harbors imprinted genes exhibits a dual nucleoprotamine/nucleohistone structure with DNase-sensitive regions, which could be implicated in the establishment of efficient epigenetic information in the developing embryo. Despite its apparent transcriptionally inert state, the sperm nucleus contains diverse RNA populations, mRNAs, antisense and miRNAs, that have been transcribed throughout spermatogenesis. There is also an endogenous reverse transcriptase that may be activated under certain circumstances. It is now commonly accepted that sperm can deliver some RNAs to the ovocyte at fertilization. This review presents potential links between male-specific genomic imprinting, chromatin organization, and the presence of diverse RNA populations within the sperm nucleus and discusses the functional significance of these RNAs in the spermatozoon itself and in the early embryo following fertilization. Some recent data are provided, supporting the view that analyzing the profile of spermatozoal RNAs could be useful for assessment of male fertility.

Steroidogenic acute regulatory protein in white sturgeon (Acipenser transmontanus): cDNA cloning, sites of expression and transcript abundance in corticosteroidogenic tissue after an acute stressor

The white sturgeon, Acipenser transmontanus, is a primitive bony fish that is recognized as an important emerging species for aquaculture. However, many aspects of its stress and reproductive physiology remain unclear. These processes are controlled by various steroid hormones. In order to investigate the regulation of steroidogenesis associated with acute stress in sturgeon, a cDNA-encoding steroidogenic acute regulatory protein (StAR) was isolated from white sturgeon. The putative amino acid sequence of sturgeon StAR shares high homology (over 60%) with other vertebrates. Phylogenetic analysis grouped sturgeon StAR within Actinopterygii, but it was clearly segregated from teleost StARs. RT-PCR analysis revealed that transcripts were most abundant in yellow corpuscles found throughout the kidney and weaker signals were detected in gonad and kidney. Very weak signals were also detected in brain and spleen by quantitative real-time PCR. In situ hybridization revealed that StAR is expressed in the cells of yellow corpuscles. No significant changes in StAR gene expression were detected in response to an acute handling stress. These results suggest that StAR is highly conserved throughout vertebrates, but the expression of the functional protein during the stress response may be partially regulated post-transcriptionally.

Y chromosome mosaicism and occurrence of gonadoblastoma in cases of Turner syndrome and amenorrhoea

In the present study, 73 cases with a clinical diagnosis of Turner syndrome, or with primary or secondary amenorrhoea without frank Turner phenotype, were evaluated for presence of low level Y chromosome mosaicism using molecular methods. Fluorescence in-situ hybridization for centromere and q arm of the Y chromosome and nested polymerase chain reaction for the sex determining region on Y (SRY) gene were performed in peripheral blood, buccal cells and gonadal biopsies. The overall frequency of Y chromosome mosaicism was found to be 18% (13/73 cases). Four cases (16%) of Turner syndrome had Y chromosome mosaicism, seven cases (28%) with primary amenorrhoea and two cases (9%) with secondary amenorrhoea had Y chromosome mosaicism. Histologically detectable gonadoblastoma was observed in one of seven cases (14%) that had Y chromosome mosaicism. This frequency is lower than that reported previously, underscoring the need for large prospective investigations to determine the frequency of Y chromosome mosaicism and occurrence of gonadoblastoma in cases of Turner syndrome and other forms of amenorrhoea.

Regulation of homeobox A10 expression in the primate endometrium by progesterone and embryonic stimuli

Homeobox A10 (HOXA10), a member of abdominal B subclass of homeobox genes, is responsible for uterine homeosis during development. Intriguingly, in the adult murine uterus, HOXA10 has been demonstrated to play important roles in receptivity, embryo implantation, and decidualization. However, the roles of HOXA10 in the primate endometrium are not known. To gain insights into the roles of HOXA10 in the primate endometrium, its expression was studied in the endometria of bonnet monkey (Macaca radiata) in the receptive phase and also in the endometria of monkeys treated with antiprogestin onapristone (ZK98.299) or in conception cycle where the presence of preimplantation stage blastocyst was verified. In addition, the mRNA expression ofHOXA11and insulin-like growth factor-binding protein 1 (IGFBP1) was evaluated by real-time PCR in these animals.The results revealed that HOXA10 in the luteal phase primate endometrium is differentially expressed in the functionalis and the basalis zones, which is modulatedin vivoby progesterone and also by the signals from the incoming embryo suggesting the involvement ofHOXA10in the process of establishment of pregnancy in primates. In addition, the results also demonstrated that the expression ofIGFBP1but notHOXA11is coregulated withHOXA10in the endometria of these animals. The pattern of changes in the expression of HOXA10 in response to the two stimuli suggests that endometrial receptivity and implantation not only requires a synchrony of maternal and embryonic signaling on endometrial cells in the primates but there also exists a controlled differential response among the cells of various uterine compartments.

Exposure of adult rats to estradiol valerate induces ovarian cyst with early senescence of follicles

Environmental and therapeutic estrogens are known to play an important role in modulating the reproductive life and pubertal maturation in males as well as in females. Animal studies have shown that exogenously administered estrogen induces follicular cysts. However, the probable mechanisms underlying this abnormal ovarian development and its impact on steroidogenesis have been ill defined. The present study was therefore carried out to understand the ontogeny of ovarian pathology owing to adult estrogenisation. Regularly cycling female Holtzman rats were sacrificed at one week, two weeks, three weeks and four weeks after a subcutaneous administration of 2 mg of estradiol valerate (E(2)V). The effect of this supra-physiological estrogen on serum endocrine profiles, development of follicular cysts, follicular apoptosis and expression of markers of folliculogenesis viz., estrogen receptor (ER)-beta, inhibin A and progesterone receptor (PR) were studied. Results indicate a temporal augmentation of steroidogenesis, which was associated with induction of follicular cyst with theca cell hyperplasia and induction of apoptosis in the primary and secondary follicles of the ovaries. Immuno-histochemical localization showed an increase in inhibin A with a reduction in ER-beta and PR indicating early maturation, poor follicle growth and granulosa cell differentiation. Results indicate that exposure to exogenous estrogen in adulthood can have deleterious effects on the ovarian physiology and endocrinology which may ultimately lead to cystogenesis, loss of follicle pool and early senescence.

Developmental expression and cellular distribution of Müllerian inhibiting substance in the primate ovary

Ovarian follicle formation during development and follicle maturation in adulthood are crucial determinants of female fertility and disruptions in these processes may result in subfertility or infertility. Among the several factors that are involved in ovarian physiology, Müllerian inhibiting substance (MIS) also known as anti-Müllerian hormone has emerged as an important marker to predict the follicle reserve. However, the roles of MIS in human ovarian physiology are unknown. To gain an insight into the potential roles of MIS in human ovarian differentiation during development and its regulation in adulthood, the expression profiles of MIS mRNA in the developing and adult human and monkey ovaries was examined byin situhybridization. The results revealed that in the fetal human ovaries, MIS is specifically expressed at low levels in the granulosa cells of the developing primordial follicles; a small subset (~2–3%) of oocytes express high amounts of MIS. In the adult human and monkey ovary, MIS mRNA is expressed at low levels in the primordial follicles, maximally in the primary and secondary follicles, and the expression is downregulated in the antral and atetric follicles. MIS expression is extinguished in the granulosa cells only after ovulation. These observations strongly favor the regulatory roles of MIS in folliculogenesis. MIS in the primate ovary may exert its effect during the primordial follicle formation to the terminal granulosa cell differentiation. The presence of MIS in a small subset of oocytes in the fetal ovary further points towards its additional role during fetal oocyte development.