A gene from the human sex-determining region encodes a protein with homology to a conserved DNA-binding motif

Therapeutic potential of SOX family transcription factors in osteoarthritis

BACKGROUND

As the worldwide population ages, osteoarthritis has significantly increased. This musculoskeletal condition has become a pressing global health issue and thus, prevention and treatment of osteoarthritis have become the primary focus of domestic and international research. Scholarly investigations of the molecular mechanisms that are related to the occurrence and development of osteoarthritis have shed light on the pathological causes of this condition to a certain extent, providing a foundation for its prevention and treatment. However, further research is necessary to fully understand the critical role of the transcription factor SOX9 in chondrocyte differentiation and the development of osteoarthritis. As a result, there has been widespread interest in SOX transcription factors. While SOX9 has been utilized as a biomarker to indicate the occurrence and prognosis of osteoarthritis, investigations into other members of the SOX family and the development of targeted treatments around SOX9 are still required.

PURPOSE

This article considers the impact of the SOX protein on the development and inhibition of osteoarthritis and highlights the need for therapeutic approaches targeting SOX9, as supported by existing research.

RESULTS

SOX9 can contribute to the process of osteoarthritis through acetylation and ubiquitination modifications. The regulation of the WNT signalling pathway, Nrf2/ARE signalling pathway, NF-κB signalling pathway and SOX9 is implicated in the emergence of osteoarthritis. Non-coding RNA may play a role in the onset and progression of osteoarthritis by modulating various SOX family members, including SOX2, SOX4, SOX5, SOX6, SOX8, SOX9 and SOX11.

CONCLUSION

SOX9 has the capability of mitigating the onset and progression of osteoarthritis through means such as medication therapy, stem cell therapy, recombinant adeno-associated virus (rAAV) vector therapy, physical therapy and other approaches.

Genome wide analysis of the sox32 gene in germline maintenance and differentiation in leopard coral grouper (Plectropomus leopardus)

The Sox family genes, as a group of transcription factors, are widely expressed in vertebrates and play a critical role in reproduction and development. The present study reported that 26 sox genes were identified from the genome and transcriptome of P. leopardus. The phylogenetic tree construction, chromosome localization, and gene structure analysis were executed to verify the evolutionary relationships, gene duplication, and deletion variations of P. leopardus sox genes in evolution. The sequence alignment revealed the HMG-box domain was highly conserved throughout the Sox gene family. The expression profile showed expression levels of sox genes showed tissue specificity. The dimorphic expression pattern of most sox genes in intersex and adult gonads was also observed, suggesting an important role of sox genes for sex differentiation in P. leopardus. Notably, sox32 was specifically highly expressed in gonadal tissues and might play a novel role within the gonads. The fluorescent in situ hybridization (FISH) showed sox32 mRNA was detected in germ stem cells and oocytes of different stages, and lowly expressed in sertoli cells. In testis, sox32 was not detected in male germ cells. Our results provided new insights into the sox32 that might be involved in gonadal development and differentiation in P. leopardus. To sum up, this study comprehensively analyzed the Sox gene family of P. leopardus and provided new insights into the function of sox genes, which could potentially revolutionize our understanding of the mechanisms of sex determination, sex differentiation, and reproductive development in fish.

SOX Genes in Spinal Cord Injury: Redefining Neural Stem Cell Regeneration Strategies

The study design is literature review. The sex-determining region Y gene (SRY)-related high mobility group box (HMG)-box (SOX) gene family has primarily been associated with neural development and sex determination and is a key component of human embryonic development. Recent studies on zebrafish models have demonstrated that the unique ability of the latter for central nervous tissue (CNS) repair following injury is largely mediated by SOX genes. Given that efforts aimed at the structural regeneration and functional restoration of neural tissue still represent a major therapeutic challenge in patients suffering CNS injury, these findings have initiated a discussion regarding the development of novel therapeutic strategies for SCI focusing on neural tissue regeneration. Spinal cord injury (SCI), in particular, represents a field that could greatly benefit from studies related to the function of the SOX genes. Neuro-informatics Laboratory, Mayo Clinic, Rochester, MN. A literature review was conducted, with a focus on SOX gene that has been described in the experimental studies of SCI. In this review, the existing evidence linking the SOX gene family to the pathophysiology of SCI is summarized, and future research steps regarding the potential implications of the SOX genes in neurological recovery following SCI are discussed, especially focusing on highlighting potential therapeutic targets. The potential implications of the latter could play a crucial role in future efforts to advance the treatment approaches to SCI.

Genome-wide identification and expression analysis of the Sox gene family in bivalves

Since the discovery of the Sox gene family in 1990, research on its distribution, classification, characterization, and function across various species has been significantly deepened. However, the Sox gene family has not yet been systematically and comprehensively analyzed in bivalves. In this study, 254 Sox genes were identified in 51 bivalves (covering 20 orders and 37 families). The Sox gene numbers ranged from 1 and 10 in most bivalves but no Sox gene was identified in the transcriptomes of Poromya illevis (Poromyoidea), Thracia phaseolina (Thracioidea), Solen vaginoides (Solenoidea), Lamychaena hians (Gastrochaenoidea), and Limopsis sp. and Solemya velesiana (Limopsoidea). The phylogenetic analyses revealed that Sox genes in bivalves are divided into 7 primary groups: SoxB1, SoxB2, SoxC, SoxD, SoxE, SoxF, and SoxH, with different groups exhibiting distinct conserved motif patterns. Notably, SoxA and SoxG found in most vertebrates were not identified in bivalves. Moreover, through spatiotemporal expression profiling in 6 distinct bivalve species, it was determined that the SoxH genes exhibit male-biased expression mainly in non-hermaphroditic bivalves, while SoxB1 and SoxC genes demonstrate female-biased expression, and these two Sox genes may serve a pivotal role in embryonic development stage and SoxB2, SoxC and SoxE may play a significant impact in neural development in bivalves. Sox family members also appear to possess disparate functions across different species and tissues. Overall, this study may provide a basis for future investigations into the functions and evolution of Sox genes in bivalves, and offer new perspectives on their roles in development in bivalves.

Gonadal sex determination in vertebrates: rethinking established mechanisms

Sex determination and differentiation are fundamental processes that are not only essential for fertility but also influence the development of many other organs, and hence, are important for species diversity and survival. In mammals, sex is determined by the inheritance of an X or a Y chromosome from the father. The Y chromosome harbours the testis-determining gene SRY, and it has long been thought that its absence is sufficient for ovarian development. Consequently, the ovarian pathway has been treated as a default pathway, in the sense that ovaries do not have or need a female-determining factor. Recently, a female-determining factor has been identified in mouse as the master regulator of ovarian development. Interestingly, this scenario was predicted as early as 1983. In this Review, we discuss the model predicted in 1983, how the mechanisms and genes currently known to be important for sex determination and differentiation in mammals have changed or supported this model, and finally, reflect on what these findings might mean for sex determination in other vertebrates.

Advances in immunological sorting of X and Y chromosome-bearing sperm: from proteome to sex-specific proteins

Sex determination is the developmental assignment that results from genetic factors. The sexual characters were the specific manifestations of male and female individuals under stimulation of sexual hormonal production. The fusion of an oocyte with an X chromosome-bearing sperm will lead to a female (XX), while fusion with a Y chromosome-bearing sperm will develop into a male (XY) in mammals. Sexing technology has been developed to fertilize eggs with sorted sperm, producing offspring of the desired sex. Sperm sorting enables the sex pre-determination of offspring via in vitro fertilization (IVF) or artificial insemination (AI) in domestic animals. Flow cytometric sorting of X and Y sperm is widely considered the most applied method for sperm sorting and has been commercially applied in cattle. However, a non-invasive, immunological method for screening X and Y sperm is considered to be a feasible approach. This review summarizes the current knowledge and techniques of sperm immunological sorting, including the preparation of antibodies, application of immunomodulators, and immunoisolation. Additionally, we focus on identifying sex-specifically expressed proteins in X and Y sperm through proteomic analysis, and verifying the sex-specific proteins using experimental techniques. Furthermore, several housekeeping proteins as loading control were discussed in immunoblotting of sperm proteins. Immunological sorting of X and Y sperm could provide a convenient, cost-effective, and highly efficient technique that can improve economic benefits and achieve an advanced level of sexing technology. This review provides insight into immunological sorting of sperm and the pre-determination of sex in farm animals.

Sex differences in age-associated neurological diseases-A roadmap for reliable and high-yield research

Once taken into consideration, sex differences in neurological diseases emerge in abundance: (i) Stroke severity is significantly higher in females than in males, (ii) Alzheimer's disease (AD) pathology is more pronounced in females, and (iii) conspicuous links with hormonal cycles led to female-specific diagnoses, such as catamenial migraines and epilepsy. While these differences receive increasing attention in isolation, they likely link to similar processes in the brain. Hence, this review aims to present an overview of the influences of sex chromosomes, hormones, and aging on male and female brains across health and disease, with a particular focus on AD and stroke. The focus here on advancements across several fields holds promise to fuel future research and to lead to an enriched understanding of the brain and more effective personalized neurologic care for all.

Comprehensive analysis of Sox genes in the Pacific oyster (Crassostrea gigas): Insights into expression and potential functions

The Sox gene family characterized by the conserved HMG-box domain, plays crucial roles in various biological processes, including development and differentiation. In this study, we identified seven Sox genes in the genome of the Pacific oyster (Crassostrea gigas), and classified them into seven subgroups: SoxB1, SoxB2, SoxC, SoxD, SoxE, SoxF, and SoxH. All Sox proteins contained the conserved HMG domain, crucial for DNA binding and transcriptional regulation. Spatial expression analysis revealed tissue-specific expression patterns: CgSoxH was highly specific to gonads, CgSoxF to the digestive gland, and CgSoxB2 subgroup to the labial palps, indicating distinct biological roles. Developmental profiling showed CgSoxB1 and CgSoxC with maternal expression, while CgSoxD and CgSoxE were active from gastrulation onwards. In gonadal development, CgSoxB1 was prominent in female gonads, while CgSoxH was associated with male gonadal maturation, suggesting the potential roles in sex differentiation. These findings provide novel insights into the functional roles of Sox genes in the reproductive and developmental processes of C. gigas.

Functional analysis of SRY variants in individuals with 46,XY differences of sex development

In mammals, male sexual development is initiated by the expression of the Sex-determining-Region-Y (SRY) gene. SRY contains a highly conserved high mobility group (HMG) box essential for DNA binding and activity. Variants in SRY cause Differences of Sex Development (DSD), accounting for 10-15% of 46, XY gonadal dysgenesis cases. Here, we present the functional analysis of five SRY coding variants identified in patients with 46, XY DSD. Four variants (p.Asp58Glu, p.Arg75Lys, p.Met85Thr, and p.Arg86Ter) are located within the HMG box and one variant (p.Tyr198Cysfs∗18) located in the C-terminal domain. We functionally characterise the impact of these variants in vitro, investigating SRY localisation and transactivational activity using SOX9 regulatory elements that are responsive to SRY. We find that three variants (p.Met85Thr, p.Arg86Ter, and p.Tyr198Cysfs∗18) have reduced or abolished transactivational activity suggesting these are pathogenic, with the p.Arg86Ter variant undetectable in our assays and the p.Met85Thr variant exhibiting reduced nuclear localisation. The pathogenic mechanisms underlying reduced activity of the novel elongated p.Tyr198Cysfs∗18 variant is however unclear, although this variant also affected localisation. In contrast, two additional variants (p.Asp58Glu and p.Arg75Lys) had no discernible effects on nuclear localisation or transactivational activity despite in silico analysis predicting impaired DNA binding. Taken together, our data establish the likely pathogenicity of these SRY variants and improve diagnostic certainty for the patients in which they were identified.

Investigating the Impact of Bismuth Oxide Nanoparticles on Dazl Gene Expression and Spermatogenesis Indices in Male Mice

Bismuth (Bi) exposure has been linked to various health effects, but its direct impact on male fertility remains largely unexplored. This study investigated the effects of bismuth oxide nanoparticles (Bi₂O₃ NPs) on male reproductive function in Naval Medical Research Institute (NMRI) mice. The mice were randomly allocated to seven groups: one control receiving physiological saline and six treatment groups receiving Bi₂O₃ NPs (25, 50, 100, 200, 400, and 800 mg/kg body weight/day) for 35 days. Treatment was administered via oral gavage. Following treatment, we evaluated body weight, blood serum biochemistry, Dazl gene expression, sperm quality, testicular histology, and cell counts (spermatogenic, Leydig, and Sertoli cells). Compared with the control, Bi₂O₃ NPs exposure resulted in significant reductions in testosterone levels, total antioxidant capacity, superoxide dismutase activity, Dazl gene expression, sperm motility, count, viability, normal morphology, and DNA integrity, and the level of malondialdehyde (MDA) increased. Additionally, testicular tissue and seminiferous tubule volume decreased, whereas interstitial tissue volume increased. Notably, sperm production was impaired, as evidenced by reduced numbers of spermatogonia, spermatocytes, spermatids, Sertoli cells, and Leydig cells. Body weight and seminiferous tubule basement membrane parameters remained largely unaffected. These findings suggest that Bi₂O₃ NPs induce oxidative stress, leading to lipid peroxidation and ultimately compromising male fertility. Our study highlights the potential detrimental effects of Bi₂O₃ NPs exposure on male reproductive health and warrants further investigation into their impact on human fertility at relevant concentrations.

Sox8: a multifaceted transcription factor in development and disease

Sox8 is a transcription factor that belongs to the Sox family of high-mobility-group domain containing proteins and is closely related to Sox9 and Sox10. During prenatal development, Sox8 is expressed in several ectoderm-, endoderm- and mesoderm-derived tissues and has been implicated in processes of organogenesis and differentiation. Sox8 expression is found in several important cells such as Sertoli cells in the male gonad, glial cells, satellite cells, and chondrocytes. However, Sox8 is not essential for the proper development of any of the involved systems, as it functions redundantly with Sox9 or Sox10 and no major developmental disturbances have been noticed in its absence. Despite its perceived limited importance as a developmental regulator, Sox8 exhibits a more significant role in late development and adult tissues. Several studies highlight the importance of Sox8 for the homeostasis of adipose tissue, Sertoli cells and the blood-testis-barrier functioning, and the maintenance of myelin in the central nervous system. Emerging evidence points to SOX8 as a promising candidate for a disease-causing gene in humans and suggests that changes in SOX8 function or expression could contribute to pathological states. For instance, genetic variants of SOX8 have been linked to multiple sclerosis and familial essential tremor, while SOX8 alterations have been related to poor cancer prognosis and infertility. This Review provides an overview of Sox8's versatile role in development and adult tissues as well as its lesser-known contributions to various diseases, and its potential as a therapeutic target.

Identification and functional analysis of sex-determining genes in the spongy moth, Lymantria dispar (lepidoptera: Erebidae)

The spongy moth (Lymantria dispar) employs a female heterogametic sex-determination system, where the female sex-determining factor (F factor) is located on the W chromosome, and the male sex-determining factor (M factor) is located on the Z chromosome. The sex-determining capabilities of the F factor and M factor vary among subspecies. Consequently, L. dispar serves as an excellent model for studying the mechanisms underlying the evolution and diversity of sex-determining genes. However, the genes encoding the F and M factors, as well as the molecular functions of their translation products, remain unidentified. In this study, we identified a L. dispar Masculinizer ortholog (LdMasc) and found that this gene is highly expressed in male embryos during the sex-determination stage. When LdMasc expression was silenced using embryonic RNA interference (RNAi), the expression pattern of L. dispar doublesex (Lddsx), the master regulatory gene for sex differentiation, shifted from the male-specific form to the female-specific form in male embryos. To identify potential F factors, we screened for genes that were exclusively expressed in females across multiple tissues and located only within the female genome. This screening yielded four unigenes with sequences displaying high homology to each other. These unigenes formed a tandem repeat, comprising approximately 100 copies within a 200 kbp region of the W chromosome-derived contig. We designated these unigenes as Fet-W (female-specifically expressed transcript from the W chromosome). RT-PCR analysis revealed that Fet-W was expressed in a female-specific manner during the sex-determination stage. Suppression of Fet-W expression by embryonic RNAi led to an increase in LdMasc expression in females and a corresponding shift in dsx expression patterns from the female-specific to the male-specific form. These findings strongly suggest that the F factor in L. dispar is Fet-W, whereas the M factor is LdMasc.

Expression of FET-1 related transcripts during chicken embryogenesis suggests a role in muscle development

The genetic basis of somatic cell identity in avian sex determination is still unknown. FET1, an endogenous retrovirus, has previously been demonstrated to be expressed during gonad development. Here, we report expression of FET1 related transcripts in non-gonadal tissue during chicken development. Both the forward and reverse FET1 related transcripts were seen in various developing muscle tissues. Both the "full-length" and partial FET1 transcripts were expressed; the latter however showed a more ubiquitous expression pattern. Female-specific gonadal expression of both sense and antisense transcripts was also confirmed. An anti-FET1 antibody, however, failed to distinguish between the predicted FET1 protein and other endogenous retroviral proteins expressed at E6.5. Our data suggest a possible role for FET1 related transcripts in sex-specific differences in muscle size and growth rate in the chickens.

Introduction to androgenetics: terminology, approaches, and impactful studies across 60 years

Across six decades, androgenetics has consistently concentrated on discovering genetic causes and enhancing the molecular diagnostics of male infertility, disorders of sex development, and their broader implications on health, such as cancer and other comorbidities. Despite vast clinical knowledge, the training of andrologists often lacks fundamental basics in medical genetics. This work, as part of the Special Issue of Andrology "Genetics in Andrology", provides the core terminology in medical genetics and technological advancements in genomics, required to understand the ever-progressing research in the field. It also gives an overview of study designs and approaches that have frequently led to discoveries in androgenetics. The rapid progress in the methodological toolbox in human genetics is illustrated by numerous examples of impactful androgenetic studies over 60 years, and their clinical implications.

Evolution and regulation of animal sex chromosomes

Animal sex chromosomes typically carry the upstream sex-determining gene that triggers testis or ovary development and, in some species, are regulated by global dosage compensation in response to functional decay of the Y chromosome. Despite the importance of these pathways, they exhibit striking differences across species, raising fundamental questions regarding the mechanisms underlying their evolutionary turnover. Recent studies of non-model organisms, including insects, reptiles and teleosts, have yielded a broad view of the diversity of sex chromosomes that challenges established theories. Moreover, continued studies in model organisms with recently developed technologies have characterized the dynamics of sex determination and dosage compensation in three-dimensional nuclear space and at single-cell resolution. Here, we synthesize recent insights into sex chromosomes from a variety of species to review their evolutionary dynamics with respect to the canonical model, as well as their diverse mechanisms of regulation.

Induced Pluripotent Stem Cells in Birds: Opportunities and Challenges for Science and Agriculture

The only cells in an organism that could do any other sort of cell until 2006 (except sperm or egg) were known as embryonic stem cells, ESC [...].

Disruption of Sex-Linked Sox3 Causes ZW Female-to-Male Sex Reversal in the Japanese Frog Glandirana rugosa

Sox3 is an ancestral homologous gene of the male-determining Sry in eutherian mammals and determines maleness in medaka fish. In the Japanese frog, Glandirana rugosa, Sox3 is located on the Z and W chromosomes. To assess the sex-determining function of Sox3 in this frog, we investigated its expression in gonads during early tadpole development and conducted genome-editing experiments. We found that the Sox3 mRNA levels in the gonads/mesonephroi were much higher in ZW females than that in ZZ males, and that the W-borne allele was dominantly expressed. A higher expression in ZW females preceded the onset of the sexually dimorphic expression of other autosomal sex differentiation genes. The Sox3 protein was detected by immunostaining in the somatic cells of early tadpole gonads around the boundary between the medulla and cortex in ZW females, whereas it was outside the gonads in ZZ males. Disrupting Sox3 using TALEN, which targets two distinct sites, generated sex-reversed ZW males and hermaphrodites, whereas no sex reversal was observed in ZZ males. These results suggest that the sex-linked Sox3 is involved in female determination in the ZZ-ZW sex-determining system of the frog, an exact opposite function to the male determination of medaka Sox3y and eutherian Sry.

Cellular trafficking and fate mapping of cells within the nervous system after in utero hematopoietic cell transplantation

In utero hematopoietic cell transplantation (IUHCT) utilizes fetal immune tolerance to achieve durable chimerism without conditioning or immunosuppression during a unique window in fetal development. Though donor cells have been observed within the nervous system following in utero injection, the timeline and distribution of cellular trafficking across the blood-brain barrier following IUHCT is not well understood. We injected 20 × 106 adult bone marrow mononuclear cells intravenously at gestational age (GA) 12-17 days and found that donor cells were maximally concentrated in the brain with treatment between GA 13-14. Donor cell engraftment persisted within the brain at every timepoint analyzed and concentrated within the hindbrain with significantly more grafted cells than in the forebrain. Additionally, transplanted cells terminally differentiated into various nervous system cellular morphologies and also populated the enteric nervous system. This study is the first to document the timeline and distribution of donor cell trafficking into the immune-protected nervous system and serves as a foundation for the application of IUHCT to treat neurogenetic diseases.

Sex chromosome turnover and biodiversity in fishes

The impact of sex chromosomes and their turnover in speciation remains a subject of ongoing debate in the field of evolutionary biology. Fishes are the largest group of vertebrates, and they exhibit unparalleled sexual plasticity, as well as diverse sex-determining (SD) genes, sex chromosomes, and sex-determination mechanisms. This diversity is hypothesized to be associated with the frequent turnover of sex chromosomes in fishes. Although it is evident that amh and amhr2 are repeatedly and independently recruited as SD genes, their relationship with the rapid turnover of sex chromosomes and the biodiversity of fishes remains unknown. We summarize the canonical models of sex chromosome turnover and highlight the vital roles of gene mutation and hybridization with empirical evidence. We revisit Haldane's rule and the large X-effect and propose the hypothesis that sex chromosomes accelerate speciation by multiplying genotypes via hybridization. By integrating recent findings on the turnover of SD genes, sex chromosomes, and sex-determination systems in fish species, this review provides insights into the relationship between sex chromosome evolution and biodiversity in fishes.

Hydin as the Candidate Master Sex Determination Gene in Channel Catfish (Ictalurus punctatus) and Its Epigenetic Regulation

Sex determination is a fascinating area of research. To date, more than 20 master sex determination (SD) genes have been reported from vertebrate animals. With channel catfish (Ictalurus punctatus), much work has been conducted to determine its master SD gene, ranging from genetic linkage mapping, genome-wide association (GWA) analysis, genome sequencing, comparative genome analysis, epigenomic analysis, transcriptome analysis, and functional studies. Here in this mini review, we provide positional, expression, regulatory, and functional evidence supporting hydin (hydrocephalus-inducing protein or HYDIN axonemal central pair apparatus protein-like) as a master SD gene in channel catfish. Hydin is located within the sex determination region (SDR) within a mapped 8.9-Mb non-recombinational segment on chromosome 4 of channel catfish. It is highly expressed in genetic males, but not in genetic females. The alleles of X and Y are highly differentially methylated with the X chromosome being hypermethylated and the Y chromosome hypomethylated. The hypomethylated Y allele of hydin is expressed while the hypermethylated X allele is not expressed. Such allelic expression fits well with the XY sex determination system of channel catfish. Functional analysis using a methylation blocker, 5-aza-dC, demonstrated that demethylation, especially within the SDR, is accompanied with increased expression of hydin, which led to sex reversal of genetic females into phenotypic males. These evidences support the candidacy of hydin as a master SD gene in channel catfish. Future knockout and analysis of affected genes after hydin knockout should provide insights into how hydin functions as a master SD gene.

The molecular basis for functional divergence of duplicated SOX factors controlling endoderm formation and left-right patterning in zebrafish

Endoderm, one of three primary germ layers of vertebrate embryos, makes major contributions to the respiratory and gastrointestinal tracts and associated organs, including liver and pancreas. In mammals, the transcription factor SOX17 is vital for endoderm organ formation and can induce endoderm progenitor identity. Duplication of ancestral sox17 in the teleost lineage produced the paralogues sox32 and sox17 in zebrafish. Sox32 is required for specification of endoderm and progenitors of the left-right organiser (Kupffer's Vesicle, KV), with Sox17 a downstream target of Sox32 that is implicated in further KV development. Phenotypic evidence therefore suggests functional similarities between zebrafish Sox32 and Sox17 and mammalian SOX17. Here, we directly compare these orthologues and paralogues, using the early zebrafish embryo as a biological platform for functional testing. Our results indicate that, unlike Sox32, human SOX17 cannot induce endoderm specification in zebrafish. Furthermore, using hybrid protein functional analyses, we show that Sox32 specificity for the endoderm gene regulatory network is linked to evolutionary divergence in its DNA-binding HMG domain from its paralogue Sox17. Additionally, changes in the C-terminal regions of Sox32 and Sox17 underpin their differing target specificities. Finally, we establish that specific conserved peptides in the C-terminal domain are essential for the role of Sox17 in establishing correct organ asymmetry. Overall, our results illuminate the molecular basis for functional divergence of Sox32 and Sox17 in vertebrate endoderm development and left-right patterning, and the evolution of SoxF transcription factor function.

Out with the old, in with the new: Meiotic driving of sex chromosome evolution

Chromosomal regions with meiotic drivers exhibit biased transmission (> 50 %) over their competing homologous chromosomal region. These regions often have two prominent genetic features: suppressed meiotic crossing over and rapidly evolving multicopy gene families. Heteromorphic sex chromosomes (e.g., XY) often share these two genetic features with chromosomal regions exhibiting meiotic drive. Here, we discuss parallels between meiotic drive and sex chromosome evolution, how the divergence of heteromorphic sex chromosomes can be influenced by meiotic drive, experimental approaches to study meiotic drive on sex chromosomes, and meiotic drive in traditional and non-traditional model organisms with high-quality genome assemblies. The newly available diversity of high-quality sex chromosome sequences allows us to revisit conventional models of sex chromosome evolution through the lens of meiotic drive.

High-quality chromosome-level genome assembly of female Artemia franciscana reveals sex chromosome and Hox gene organization

Artemia is a crustacean genus belonging to the order Anostraca in the class Branchiopoda and lives in inland hypersaline lakes. Among the genus, A. franciscana is a valuable species as a fish food in the aquaculture industry or as an aquatic model organism for toxicity tests. However, genomic data for A. franciscana remains incomplete. In this study, high-quality genome assembly at the chromosome level of female A. franciscana was conducted by combining various sequencing and assembly technologies. The final A. franciscana assembled genome was 1.27 Gb in length, containing 21 chromosomal scaffolds (>10 Mb). The scaffold N50 was 45.3 Mb, with a complete BUSCO value of 91.0 %, thereby confirming that a high-quality genome was assembled. Gene annotation shows that the A. franciscana genome contained 67.26 % of repetitive sequences, and a total of 26,923 protein-coding genes were predicted. Among the 21 chromosome-scale scaffolds, chromosome 1 was identified as a sex chromosome Z. Additionally, five contigs of putative W chromosome fragments and the candidate sex-determining genes were suggested. Ten homeobox (Hox) genes were identified in A. franciscana on the chromosome 14, which were in two subclusters with a large gap. Hox gene organizations within 13 arthropods showed that four anostracans had conserved synteny. This study provides a new female Artemia genome with sex chromosome and the first complete genomic arrangement of the Hox cluster in Anostraca. This study will be a useful genomic and genetic reference for understanding the evolution and development of A. franciscana.

Integration of long-read sequencing, DNA methylation and gene expression reveals heterogeneity in Y chromosome segment lengths in phenotypic males with 46,XX testicular disorder/difference of sex development

BACKGROUND

46,XX testicular disorder/difference of sex development (46,XX DSD) is a rare congenital condition, characterized by a combination of the typical female sex chromosome constitution, 46,XX, and a variable male phenotype. In the majority of individuals with 46,XX DSD, a Y chromosome segment containing the sex-determining region gene (SRY) has been translocated to the paternal X chromosome. However, the precise genomic content of the translocated segment and the genome-wide effects remain elusive.

METHODS

We performed long-read DNA sequencing, RNA sequencing and DNA methylation analyses on blood samples from 46,XX DSD (n = 11), male controls (46,XY; variable cohort sizes) and female controls (46,XX; variable cohort sizes), in addition to RNA sequencing and DNA methylation analysis on blood samples from males with Klinefelter syndrome (47,XXY, n = 22). We also performed clinical measurements on all 46,XX DSD and a subset of 46,XY (n = 10).

RESULTS

We identified variation in the translocated Y chromosome segments, enabling subcategorization into 46,XX DSD (1) lacking Y chromosome material (n = 1), (2) with short Yp arms (breakpoint at 2.7-2.8 Mb, n = 2), (3) with medium Yp arms (breakpoint at 7.3 Mb, n = 1), and (4) with long Yp arms (n = 7), including deletions of AMELY, TBLY1 and in some cases PRKY. We also identified variable expression of the X-Y homologues PRKY and PRKX. The Y-chromosomal transcriptome and methylome reflected the Y chromosome segment lengths, while changes to autosomal and X-chromosomal regions indicated global effects. Furthermore, transcriptional changes tentatively correlated with phenotypic traits of 46,XX DSD, including reduced height, lean mass and testicular size.

CONCLUSION

This study refines our understanding of the genetic composition in 46,XX DSD, describing the translocated Y chromosome segment in more detail than previously and linking variability herein to genome-wide changes in the transcriptome and methylome.

Gsdf is not indispensable for male differentiation in the medaka species Oryzias hubbsi

Sex determination mechanisms differ widely among vertebrates, particularly in fish species, where diverse sex chromosomes and sex-determining genes have evolved. However, the sex-differentiation pathways activated by these sex-determining genes appear to be conserved. Gonadal soma-derived growth factor (Gsdf) is one of the genes conserved across teleost fish, especially in medaka fishes of the genus Oryzias, and is implicated in testis differentiation and germ cell proliferation. However, its role in sex differentiation remains unclear. In this study, we investigated Gsdf function in Oryzias hubbsi, a species with a ZW sex-determination system. We confirmed its male-dominant expression, as in other species. However, histological analyses revealed no male-to-female sex reversal in Gsdf-knockout fish, contrary to findings in other medaka species. Genetic sex determination remained intact without Gsdf function, indicating a Gsdf-independent sex-differentiation pathway in O. hubbsi. Instead, Gsdf loss led to germ cell overproliferation in both sexes and accelerated onset of meiosis in testes, suggesting a role in germ cell proliferation. Notably, the feminizing effect of germ cells observed in O. latipes was absent, suggesting diverse germ cell-somatic cell relationships in Oryzias gonad development. Our study highlights species-specific variations in the molecular pathways governing sex determination and differentiation, emphasizing the need for further exploration to elucidate the complexities of sexual development.

Prevalence of sex-chromosome aneuploidy estimated using SNP genotype intensity information in a large population of juvenile dairy and beef cattle

Aneuploidy is a genetic condition characterized by the loss or gain of one or more chromosomes. Aneuploidy affecting the sex chromosomes can lead to infertility in otherwise externally phenotypically normal cattle. Early identification of cattle with sex chromosomal aneuploidy is important to minimize the costs associated with rearing infertile cattle and futile breeding attempts. As most livestock breeding programs routinely genotype their breeding populations using single nucleotide polymorphism (SNP) arrays, this study aimed to assess the feasibility of integrating an aneuploidy screening tool into the existing pipelines that handle dense SNP genotype data. A further objective was to estimate the prevalence of sex chromosome aneuploidy in a population of 146,431 juvenile cattle using available genotype intensity data. Three genotype intensity statistics were used: the LogR Ratio (LRR), R-value (the sum of X and Y SNP probe intensities), and B-allele frequency (BAF) measurements. Within the female-verified population of 124,958 individuals, the estimated prevalence rate was 0.0048% for XO, 0.0350% for XXX, and 0.0004% for XXY. The prevalence of XXY in the male-verified population was 0.0870% (i.e., 18 out of 20,670 males). Cytogenetic testing was used to verify 2 of the XXX females who were still alive. The proposed approach can be readily integrated into existing genomic pipelines, serving as an efficient, large-scale screening tool for aneuploidy. Its implementation could enable the early identification of infertile animals with sex-chromosome aneuploidy.

46 XX Ovotesticular Disorder of Sex Development with Gonadotropin-Releasing Hormone Receptor, Autosomal Recessive Heterozygous Missense Mutation and Autosomal Dominant Heterozygous Missense Mutation of the PROKR2 Gene: A Case Report

True hermaphroditism is a disorder of sex development (DSD), accounting for less than 5% of all DSD cases, defined by the simultaneous presence of testicular tissue and ovarian tissue in the same individual. In the reported case, the patient presented two genetic mutations involved in the pathogenic pathway of the DSD condition associated with the clinical features of Kallmann syndrome (KS), a developmental disease that associates hypogonadotropic hypogonadism (HH), due to gonadotropin-releasing hormone deficiency, and anosmia, related to the absence or hypoplasia of the olfactory bulbs. Given the variable degree of hyposmia in KS, the distinction between KS and normosmic idiopathic HH is currently unclear, especially as HH patients do not always undergo detailed olfactory testing. This syndrome is very rare, with an estimated prevalence of 1:80,000 in males and 1:40,000 in females. This is the only case report concerning a patient with 46 XX true hermaphroditism affected by HH and digenic inheritance of Kallmann syndrome.

The Reproductive Lifespan of Ovarian Follicle

The functional unit within mammalian ovaries is the ovarian follicle. The development of the ovarian follicle is a lengthy process beginning from the time of embryogenesis, passing through multiple different stages of maturation. The purpose of this review is to describe the most basic events in the journey of ovarian follicle development, discussing the importance of ovarian reserve and highlighting the role of several factors that affect oocyte quality and quantity during aging including hormonal, genetic and epigenetic factors. Novel, promising anti-aging strategies are also discussed.

Role of nucleobase-specific interactions in the binding and bending of DNA by human male sex determination factor SRY

Y-chromosome-encoded master transcription factor SRY functions in the embryogenesis of therian mammals to initiate male development. Through interactions of its conserved high-mobility group box within a widened DNA minor groove, SRY and related Sox factors induce sharp bends at specific DNA target sites. Here, we present the crystal structure of the SRY high-mobility group domain bound to a DNA site containing consensus element 5'-ATTGTT. The structure contains three complexes in the asymmetric unit; in each complex, SRY forms 10 hydrogen bonds with minor-groove base atoms in 5'-CATTGT/ACAATG-3', shifting the recognition sequence by one base pair (italics). These nucleobase interactions involve conserved residues Arg7, Asn10, and Tyr74 on one side of intercalated Ile13 (the cantilever) and Arg20, Asn32, and Ser36 on the other. Unlike the less-bent NMR structure, DNA bend angles (69-84°) of the distinct box-DNA complexes are similar to those observed in homologous Sox domain-DNA structures. Electrophoretic studies indicate that respective substitutions of Asn32, Ser36, or Tyr74 by Ala exhibit slightly attenuated specific DNA-binding affinity and bend angles (70-73°) relative to WT (79°). By contrast, respective substitutions of Arg7, Asn10, or Arg20 by Ala markedly impaired DNA-binding affinity in association with much smaller DNA bend angles (53-65°). In a rodent cell-based model of the embryonic gonadal ridge, full-length SRY variants bearing these respective Ala substitutions exhibited significantly decreased transcriptional activation of SRY's principal target gene (Sox9). Together, our findings suggest that nucleobase-specific hydrogen bonds by SRY are critical for specific DNA binding, bending, and transcriptional activation.

Complex genomic rearrangements of the Y chromosome in a premature infant

BACKGROUND

Chromoanagenesis is an umbrella term used to describe catastrophic "all at once" cellular events leading to the chaotic reconstruction of chromosomes. It is characterized by numerous rearrangements involving a small number of chromosomes/loci, copy number gains in combination with deletions, reconstruction of chromosomal fragments with improper order/orientation, and preserved heterozygosity in copy number neutral regions. Chromoanagesis is frequently described in association with cancer; however, it has also been described in the germline. The clinical features associated with constitutional chromoanagenesis are typically due to copy number changes and/or disruption of genes or regulatory regions.

CASE PRESENTATION

We present an 8-year-old male patient with complex rearrangements of the Y chromosome including a ring Y chromosome, a derivative Y;21 chromosome, and a complex rearranged Y chromosome. These chromosomes were characterized by G-banded chromosome analysis, SNP microarray, interphase FISH, and metaphase FISH. The mechanism(s) by which these rearrangements occurred is unclear; however, it is evocative of chromoanagenesis.

CONCLUSION

This case is a novel example of suspected germline chromoanagenesis leading to large copy number changes that are well-tolerated, possibly because only the sex chromosomes are affected.

[Sex determination, it is all about timing]

The sex of an individual is determined at the time of fertilization. The mother passes on one sex chromosome, the X chromosome, and the father transmits the second sex chromosome, X or Y. Thus, an XX embryo becomes a female, whereas an XY individual becomes a male. A process known as "primary sex determination" allows the bipotential gonad to become a testis or an ovary in XY and XX embryos, respectively. In 1990, the Sry gene, located on the Y chromosome, was found to be necessary and sufficient to induce the male developmental program. At this time, the scientific community thought that other genes involved in the process of sex determination would be rapidly identified. However, it took more than 30 years to identify the ovarian determining factor. This factor is one variant of WT1, denoted -KTS, which is required to induce ovarian development in XX mice and can prevent male development of the gonad when it is prematurely activated in XY embryos. Because the -KTS variant of WT1 acts very early during development, this discovery opens new avenues for research on ovarian development, as it happened for SRY for testis development. It will also lead to a better understanding of the regulatory gene networks implicated in many unresolved cases of sex development disorders.

Sex chromosome-encoded protein homologs: current progress and open questions

The complexity of biological sex differences is markedly evident in human physiology and pathology. Although many of these differences can be ascribed to the expression of sex hormones, another contributor to sex differences lies in the sex chromosomes beyond their role in sex determination. Although largely nonhomologous, the human sex chromosomes express seventeen pairs of homologous genes, referred to as the 'X-Y pairs.' The X chromosome-encoded homologs of these Y-encoded proteins are crucial players in several cellular processes, and their dysregulation frequently results in disease development. Many diseases related to these X-encoded homologs present with sex-biased incidence or severity. By contrast, comparatively little is known about the differential functions of the Y-linked homologs. Here, we summarize and discuss the current understanding of five of these X-Y paired proteins, with recent evidence of differential functions and of having a potential link to sex biases in disease, highlighting how amino acid-level sequence differences may differentiate their functions and contribute to sex biases in human disease.

The multifaceted role of SOX2 in breast and lung cancer dynamics

Breast and lung cancers are leading causes of death among patients, with their global mortality and morbidity rates increasing. Conventional treatments often prove inadequate due to resistance development. The alteration of molecular interactions may accelerate cancer progression and treatment resistance. SOX2, known for its abnormal expression in various human cancers, can either accelerate or impede cancer progression. This review focuses on examining the role of SOX2 in breast and lung cancer development. An imbalance in SOX2 expression can promote the growth and dissemination of these cancers. SOX2 can also block programmed cell death, affecting autophagy and other cell death mechanisms. It plays a significant role in cancer metastasis, mainly by regulating the epithelial-to-mesenchymal transition (EMT). Additionally, an imbalanced SOX2 expression can cause resistance to chemotherapy and radiation therapy in these cancers. Genetic and epigenetic factors may affect SOX2 levels. Pharmacologically targeting SOX2 could improve the effectiveness of breast and lung cancer treatments.

Sex chromosome cycle as a mechanism of stable sex determination

Recent advances in DNA sequencing technology have enabled the precise decoding of genomes in non-model organisms, providing a basis for unraveling the patterns and mechanisms of sex chromosome evolution. Studies of different species have yielded conflicting results regarding the traditional theory that sex chromosomes evolve from autosomes via the accumulation of deleterious mutations and degeneration of the Y (or W) chromosome. The concept of the 'sex chromosome cycle,' emerging from this context, posits that at any stage of the cycle (i.e., differentiation, degeneration, or loss), sex chromosome turnover can occur while maintaining stable sex determination. Thus, understanding the mechanisms that drive both the persistence and turnover of sex chromosomes at each stage of the cycle is crucial. In this review, we integrate recent findings on the mechanisms underlying maintenance and turnover, with a special focus on several organisms having unique sex chromosomes. Our review suggests that the diversity of sex chromosomes in the maintenance of stable sex determination is underappreciated and emphasizes the need for more research on the sex chromosome cycle.

RNA Binding Properties of SOX Family Members

SOX proteins are a family of transcription factors (TFs) that play critical functions in sex determination, neurogenesis, and chondrocyte differentiation, as well as cardiac, vascular, and lymphatic development. There are 20 SOX family members in humans, each sharing a 79-residue L-shaped high mobility group (HMG)-box domain that is responsible for DNA binding. SOX2 was recently shown to interact with long non-coding RNA and large-intergenic non-coding RNA to regulate embryonic stem cell and neuronal differentiation. The RNA binding region was shown to reside within the HMG-box domain; however, the structural details of this binding remain unclear. Here, we show that all SOX family members, except group H, interact with RNA. Our mutational experiments demonstrate that the disordered C-terminal region of the HMG-box domain plays an important role in RNA binding. Further, by determining a high-resolution structure of the HMG-box domain of the group H family member SOX30, we show that despite differences in RNA binding ability, SOX30 shares a very similar secondary structure with other SOX protein HMG-box domains. Together, our study provides insight into the interaction of SOX TFs with RNA.

Structure and Functions of HMGB3 Protein

HMGB3 protein belongs to the group of HMGB proteins from the superfamily of nuclear proteins with high electrophoretic mobility. HMGB proteins play an active part in almost all cellular processes associated with DNA-repair, replication, recombination, and transcription-and, additionally, can act as cytokines during infectious processes, inflammatory responses, and injuries. Although the structure and functions of HMGB1 and HMGB2 proteins have been intensively studied for decades, very little attention has been paid to HMGB3 until recently. In this review, we summarize the currently available data on the molecular structure, post-translational modifications, and biological functions of HMGB3, as well as the possible role of the ubiquitin-proteasome system-dependent HMGB3 degradation in tumor development.

Insights from Hi-C data regarding the Pacific salmon louse (Lepeophtheirus salmonis) sex chromosomes

Salmon lice, Lepeophtheirus salmonis (family Caligidae), are ectoparasites that have negatively impacted the salmon aquaculture industry and vulnerable wild salmon populations. Researchers have studied salmon lice to better understand their biology to develop effective control strategies. In this study, we updated the chromosome-level reference genome assembly of the Pacific subspecies of L. salmonis using Hi-C data. The previous version placed contigs/scaffolds using an Atlantic salmon louse genetic map. By utilizing Hi-C data from Pacific salmon lice, we were able to properly assign locations to contigs/scaffolds previously unplaced or misplaced. This resulted in a more accurate genome assembly and a more comprehensive characterization of the sex chromosome unique to females (W). We found evidence that the same ZW-ZZ mechanism is common in both Atlantic and Pacific subspecies of salmon lice using PCR assays. The W chromosome was approximately 800 kb in size, which is ∼30 times smaller than the Z chromosome (24 Mb). The W chromosome contained 61 annotated genes, including 32 protein-coding genes, 27 long noncoding RNA (lncRNA) genes, and 2 pseudogenes. Among these 61 genes, 39 genes shared homology to genes found on other chromosomes, while 20 were unique to the W chromosome. Two genes of interest on the W chromosome, prohibitin-2 and kinase suppressor of ras-2, were previously identified as potential sex-linked markers in the salmon louse. However, we prioritized the 20 unique genes on the W chromosome as sex-determining candidates. This information furthers our understanding of the biology of this ectoparasite and may help in the development of more effective management strategies.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Multi-omic characterization of allele-specific regulatory variation in hybrid pigs

Hybrid mapping is a powerful approach to efficiently identify and characterize genes regulated through mechanisms in cis. In this study, using reciprocal crosses of the phenotypically divergent Duroc and Lulai pig breeds, we perform a comprehensive multi-omic characterization of regulatory variation across the brain, liver, muscle, and placenta through four developmental stages. We produce one of the largest multi-omic datasets in pigs to date, including 16 whole genome sequenced individuals, as well as 48 whole genome bisulfite sequencing, 168 ATAC-Seq and 168 RNA-Seq samples. We develop a read count-based method to reliably assess allele-specific methylation, chromatin accessibility, and RNA expression. We show that tissue specificity was much stronger than developmental stage specificity in all of DNA methylation, chromatin accessibility, and gene expression. We identify 573 genes showing allele specific expression, including those influenced by parent-of-origin as well as allele genotype effects. We integrate methylation, chromatin accessibility, and gene expression data to show that allele specific expression can be explained in great part by allele specific methylation and/or chromatin accessibility. This study provides a comprehensive characterization of regulatory variation across multiple tissues and developmental stages in pigs.

Implications of a De Novo Variant in the SOX12 Gene in a Patient with Generalized Epilepsy, Intellectual Disability, and Childhood Emotional Behavioral Disorders

SRY-box transcription factor (SOX) genes, a recently discovered gene family, play crucial roles in the regulation of neuronal stem cell proliferation and glial differentiation during nervous system development and neurogenesis. Whole exome sequencing (WES) in patients presenting with generalized epilepsy, intellectual disability, and childhood emotional behavioral disorder, uncovered a de novo variation within SOX12 gene. Notably, this gene has never been associated with neurodevelopmental disorders. No variants in known genes linked with the patient's symptoms have been detected by the WES Trio analysis. To date, any MIM phenotype number associated with intellectual developmental disorder has not been assigned for SOX12. In contrast, both SOX4 and SOX11 genes within the same C group (SoxC) of the Sox gene family have been associated with neurodevelopmental disorders. The variant identified in the patient here described was situated within the critical high-mobility group (HMG) functional site of the SOX12 protein. This domain, in the Sox protein family, is essential for DNA binding and bending, as well as being responsible for transcriptional activation or repression during the early stages of gene expression. Sequence alignment within SoxC (SOX12, SOX4 and SOX11) revealed a high conservation rate of the HMG region. The in silico predictive analysis described this novel variant as likely pathogenic. Furthermore, the mutated protein structure predictions unveiled notable changes with potential deleterious effects on the protein structure. The aim of this study is to establish a correlation between the SOX12 gene and the symptoms diagnosed in the patient.

Inhibition of WNT/β-catenin signalling during sex-specific gonadal differentiation is essential for normal human fetal testis development

Sex-specific gonadal differentiation is directed by complex signalling promoting development in either male or female direction, while simultaneously inhibiting the opposite pathway. In mice, the WNT/β-catenin pathway promotes ovarian development and the importance of actively inhibiting this pathway to ensure normal testis development has been recognised. However, the implications of alterations in the tightly regulated WNT/β-catenin signalling during human fetal gonad development has not yet been examined in detail. Thus, the aim of this study was to examine the consequences of dysregulating the WNT/β-catenin signalling pathway in the supporting cell lineage during sex-specific human fetal gonad development using an established and extensively validated ex vivo culture model. Inhibition of WNT/β-catenin signalling in human fetal ovary cultures resulted in only minor effects, including reduced secretion of RSPO1 and reduced cell proliferation although this was not consistently found in all treatment groups. In contrast, promotion of WNT/β-catenin signalling in testes severely affected development and function. This included disrupted seminiferous cord structures, reduced cell proliferation, reduced expression of SOX9/AMH, reduced secretion of Inhibin B and AMH as well as loss of the germ cell population. Additionally, Leydig cell function was markedly impaired with reduced secretion of testosterone, androstenedione and INSL3. Together, this study suggests that dysregulated WNT/β-catenin signalling during human fetal gonad development severely impairs testicular development and function. Importantly, our study highlights the notion that sufficient inhibition of the opposite pathway during sex-specific gonadal differentiation is essential to ensure normal development and function also applies to human fetal gonads.

Two redundant transcription factor binding sites in a single enhancer are essential for mammalian sex determination

Male development in mammals depends on the activity of the two SOX gene: Sry and Sox9, in the embryonic testis. As deletion of Enhancer 13 (Enh13) of the Sox9 gene results in XY male-to-female sex reversal, we explored the critical elements necessary for its function and hence, for testis and male development. Here, we demonstrate that while microdeletions of individual transcription factor binding sites (TFBS) in Enh13 lead to normal testicular development, combined microdeletions of just two SRY/SOX binding motifs can alone fully abolish Enh13 activity leading to XY male-to-female sex reversal. This suggests that for proper male development to occur, these few nucleotides of non-coding DNA must be intact. Interestingly, we show that depending on the nature of these TFBS mutations, dramatically different phenotypic outcomes can occur, providing a molecular explanation for the distinct clinical outcomes observed in patients harboring different variants in the same enhancer.

Decoding the epigenetic mechanism of mammalian sex determination

Sex determination embodies a dynamic and intricate developmental process wielding significant influence over the destiny of bipotential gonads, steering them towards male or female gonads. Gonadal differentiation and the postnatal manifestation of the gonadal phenotype involve a sophisticated interplay of transcription factors such as SOX9 and FOXL2. Central to this interplay are chromatin modifiers regulating the mutual antagonism during this interplay. In this review, the key findings and knowledge gaps in DNA methylation, histone modification, and non-coding RNA-mediated control throughout mammalian gonadal development are covered. Furthermore, it explores the role of the developing brain in playing a pivotal role in the initiation of gonadogenesis and the subsequent involvement of gonadal hormone/hormone receptor in fine-tuning sexual differentiation. Based on promising facts, the role of the developing brain through the hypothalamic pituitary gonadal axis is explained and suggested as a novel hypothesis. The article also discusses the potential impact of ecological factors on the human epigenome in relation to sex determination and trans-generational epigenetics in uncovering novel genes and mechanisms involved in sex determination and gonadal differentiation. We have subtly emphasized the disruptions in epigenetic regulations contributing to sexual disorders, which further allows us to raise certain questions, decipher approaches for handling these questions and setting up the direction of future research.

Genome-wide identification and expression analysis of Sox gene family in the Manila clam (Ruditapes philippinarum)

Sox transcription factors are vital in numerous fundamental biological processes. In this study, nine Sox gene family members were discovered in the Ruditapes philippinarum genome, classified into the SoxB1, SoxB2, SoxC, SoxD, SoxE, and SoxF groups, marking the first genome-wide identification of this gene family in R. philippinarum. Analyses of phylogeny, exon-intron structures, and domains bolster the support for their categorization and annotation. Furthermore, transcriptomic analyses across various developmental stages revealed that RpSox4, RpSox5, RpSox9, and RpSox11 were significantly expressed in the D-larval stage. Additionally, investigations into transcriptomes of clams with different shell colors indicated that most sox genes exhibited their highest expression levels in orange clams, followed by zebra, white zebra, and white clams, and the results of transcriptomes analysis in different tissues indicated that 8 Sox genes (except RpSox17) were highly expressed in the mantle tissue. Moreover, qPCR was used to detect the expression of Sox gene in R. philippinarum at different developmental periods, different shell colors and different tissues, and the results showed consistency with those of the transcriptomes. This study's findings lay the groundwork for additional exploration into the role of the Sox gene in melanin production in R. philippinarum shells.

46,XX Differences of Sex Development outside congenital adrenal hyperplasia: pathogenesis, clinical aspects, puberty, sex hormone replacement therapy and fertility outcomes

The term 'differences of sex development' (DSD) refers to a group of congenital conditions that are associated with atypical development of chromosomal, gonadal, and/or anatomical sex. DSD in individuals with a 46,XX karyotype can occur due to fetal or postnatal exposure to elevated amount of androgens or maldevelopment of internal genitalia. Clinical phenotype could be quite variable and for this reason these conditions could be diagnosed at birth, in newborns with atypical genitalia, but also even later in life, due to progressive virilization during adolescence, or pubertal delay. Understand the physiological development and the molecular bases of gonadal and adrenal structures is crucial to determine the diagnosis and best management and treatment for these patients. The most common cause of DSD in 46,XX newborns is congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, determining primary adrenal insufficiency and androgen excess. In this review we will focus on the other rare causes of 46,XX DSD, outside CAH, summarizing the most relevant data on genetic, clinical aspects, puberty and fertility outcomes of these rare diseases.

Complete male-to-female sex reversal in XY mice lacking the miR-17~92 cluster

Mammalian sex determination is controlled by antagonistic gene cascades operating in embryonic undifferentiated gonads. The expression of the Y-linked gene SRY is sufficient to trigger the testicular pathway, whereas its absence in XX embryos leads to ovarian differentiation. Yet, the potential involvement of non-coding regulation in this process remains unclear. Here we show that the deletion of a single microRNA cluster, miR-17~92, induces complete primary male-to-female sex reversal in XY mice. Sry expression is delayed in XY knockout gonads, which develop as ovaries. Sertoli cell differentiation is reduced, delayed and unable to sustain testicular development. Pre-supporting cells in mutant gonads undergo a transient state of sex ambiguity which is subsequently resolved towards the ovarian fate. The miR-17~92 predicted target genes are upregulated, affecting the fine regulation of gene networks controlling gonad development. Thus, microRNAs emerge as key components for mammalian sex determination, controlling Sry expression timing and Sertoli cell differentiation.

Unbalanced X;Y translocations carrying SRY in prenatal settings: Clinical, molecular, and cytogenetic analysis of three cases

BACKGROUND

Generally, the translocation of SRY onto one of the X chromosomes leads to 46, XX testicular disorders of sex development, a relatively rare condition characterized by the presence of testicular tissue with a 46, XX karyotype. Three prenatal cases of unbalanced X; Y translocation carrying SRY were identified in this study.

METHODS

Structural variants were confirmed using single nucleotide polymorphism array and chromosomal karyotyping. X chromosome inactivation (XCI) was also analyzed. Detailed clinical features of the three cases were collected.

RESULTS

We identified two fetuses with maternal inherited unbalanced X; Y translocations carrying SRY and skewed XCI presenting with normal female external genitalia, and one fetus with de novo 46, XX (SRY+) and random XCI manifested male phenotypic external genitalia.

CONCLUSION

This study reports that cases with unbalanced X; Y translocations carrying SRY manifested a normal female external genitalia in a prenatal setting. We speculate that the skewed XCI mediates the silence of SRY. In addition, our study emphasizes that combining clinical findings with pedigree analysis is critical for estimating the prognosis of fetuses with sex chromosome abnormalities.

A delayed and unsynchronized ovary development as revealed by transcriptome of brain and pituitary of Coilia nasus

Coilia nasus is an anadromous fish that has been successfully domesticated in the last decade due to its high economic value. The fish exhibits a delayed ovary development during the reproductive season, despite breeding and selection for five to six offspring. The molecular mechanism of the delayed ovary development is still unknown, so the obstacles have not been removed in the large-scale breeding program. This study aims to investigate the key genes regulating ovarian development by comparing the transcriptomes of ovarian-stage IV and stage II brain/pituitary of Coilia nasus. Ovarian stages were validated by histological sections. A total of 75,097,641 and 66,735,592 high-quality reads were obtained from brain and pituitary transcriptomes, respectively, and alternatively spliced transcripts associated with gonadal development were detected. Compared to ovarian Ⅱ- brain, 515 differentially expressed genes (DEGs) were upregulated and 535 DEGs were downregulated in ovarian Ⅳ- brain, whereas 470 DEGs were upregulated and 483 DEGs were downregulated in ovarian Ⅳ- pituitary compared to ovarian Ⅱ- pituitary. DEGs involved in hormone synthesis and secretion and in the GnRH signaling pathway were screened. Weighted gene co-expression network analysis identified gene co-expression modules that were positively correlated with ovarian phenotypic traits. The hub genes Smad4 and TRPC4 in the modules were co-expressed with DEGs including Kiss1 receptor and JUNB, suggesting that ovarian development is controlled by a hypothalamic-pituitary-gonadal axis. Our results have provided new insights that advance our understanding of the molecular mechanism of C. nasus reproductive functions and will be useful for future breeding.