Insights Into the Roles of GATA Factors in Mammalian Testis Development and the Control of Fetal Testis Gene Expression

GATA3: Orchestrating cellular fate through differentiation and proliferation

Cell proliferation and differentiation are two fundamental biological processes that occur in biological systems, tightly regulated by various factors such as transcription factors (TFs). Zinc finger proteins are TFs responsible for maintaining the biological balance via coordinating development and functionality within the living cells. GATA binding protein 3 (GATA3), one of the zinc finger proteins, plays an essential role in driving differentiation and proliferation-related processes, thereby contributing to the regulation of the dynamism and productivity of living cells. By elucidating the complex interactions governed by GATA3, this underscores its significance in maintaining cellular homeostasis. Thus, the current review delves into the molecular pathways influenced by GATA3, highlighting its involvement in multiple developmental processes of various tissues and body sites, particularly in the hematopoietic system (T-cell differentiation), neural tissue differentiation, adipose tissue, as well as epithelial cell maturation.

GATA4: Regulation of expression and functions in goat granulosa cells

GATA4 plays a pivotal role in the reproductive processes of mammals. However, the research on GATA4 in goat ovary is limited. This study aimed to study the expression and function of GATA4 in goat ovary. Utilizing real-time PCR and western blot analysis, we studied the expression and regulatory mechanisms of GATA4 in goat ovary and granulosa cells (GCs). We found that GATA4 was expressed in all follicle types in the goat ovary, with significantly higher levels in GCs of larger follicles (>3 mm) compared to those in smaller follicles (<3 mm). Additionally, we demonstrated that human chorionic gonadotrophin (hCG) induced GATA4 mRNA expression via the activation of PKA, MEK, p38 MAPK, PKC, and PI3K pathways in vitro. Our study also showed that hCG suppressed the levels of miR-200b and miR-429, which in turn directly target GATA4, thereby modulating the basal and hCG-induced expression of GATA4. Functionally, we examined the effect of siRNA-mediated GATA4 knockdown on cell proliferation and hormone secretion in goat GCs. Our results revealed that knockdown of GATA4, miR-200b, and miR-429 suppressed cell proliferation. Moreover, knockdown of GATA4 decreased estradiol and progesterone production by inhibiting the promoter activities of CYP11A1, CYP19A1, HSD3B, and StAR. Collectively, our findings suggest a critical involvement of GATA4 in regulating goat GC survival and steroidogenesis.

Complete characterization of the yak testicular development using accurate full-length transcriptome sequencing

Alternative splicing is a prevalent phenomenon in testicular tissues. Due to the low assembly accuracy of short-read RNA sequencing technology in analyzing post-transcriptional regulatory events, full-length (FL) transcript sequencing is highly demanded to accurately determine FL splicing variants. In this study, we performed FL transcriptome sequencing of testicular tissues from 0.5, 1.5, 2.5, and 4-year-old yaks and 4-year-old cattle-yaks using Oxford Nanopore Technologies. The obtained sequencing data were predicted to have 47,185 open reading frames (ORFs), including 26,630 complete ORFs, detected 7645 fusion transcripts, 15,355 alternative splicing events, 25,798 simple sequence repeats, 7628 transcription factors, and 35,503 long non-coding RNAs. A total of 40,038 novel transcripts were obtained from the sequencing data, and the proportion was almost close to the number of known transcripts identified. Structural analysis and functional annotation of these novel transcripts resulted in the successful annotation of 9568 transcripts, with the highest and lowest annotation numbers in the Nr and KOG databases, respectively. Weighted gene co-expression network analysis revealed the key regulatory pathways and hub genes at various stages of yak testicular development. Our findings enhance our comprehension of transcriptome complexity, contribute to genome annotation refinement, and provide foundational data for further investigations into male sterility in cattle-yaks.

A role for TRPC3 in mammalian testis development

SOX9 is a key transcription factor for testis determination and development. Mutations in and around the SOX9 gene contribute to Differences/Disorders of Sex Development (DSD). However, a substantial proportion of DSD patients lack a definitive genetic diagnosis. SOX9 target genes are potentially DSD-causative genes, yet only a limited subset of these genes has been investigated during testis development. We hypothesize that SOX9 target genes play an integral role in testis development and could potentially be causative genes in DSD. In this study, we describe a novel testicular target gene of SOX9, Trpc3. Trpc3 exhibits high expression levels in the SOX9-expressing male Sertoli cells compared to female granulosa cells in mouse fetal gonads between embryonic day 11.5 (E11.5) and E13.5. In XY Sox9 knockout gonads, Trpc3 expression is markedly downregulated. Moreover, culture of E11.5 XY mouse gonads with TRPC3 inhibitor Pyr3 resulted in decreased germ cell numbers caused by reduced germ cell proliferation. Trpc3 is also expressed in endothelial cells and Pyr3-treated E11.5 XY mouse gonads showed a loss of the coelomic blood vessel due to increased apoptosis of endothelial cells. In the human testicular cell line NT2/D1, TRPC3 promotes cell proliferation and controls cell morphology, as observed by xCELLigence and HoloMonitor real-time analysis. In summary, our study suggests that SOX9 positively regulates Trpc3 in mouse testes and TRPC3 may mediate SOX9 function during Sertoli, germ and endothelial cell development.

Rhox8 homeobox gene ablation leads to rete testis abnormality and male subfertility in mice†

The reproductive homeobox X-linked (Rhox) genes encode transcription factors that are expressed selectively in reproductive tissues including the testis, epididymis, ovary, and placenta. While many Rhox genes are expressed in germ cells in the mouse testis, only Rhox8 is expressed exclusively in the Sertoli cells during embryonic and postnatal development, suggesting a possible role of Rhox8 in embryonic gonad development. Previously, Sertoli cell-specific knockdown of RHOX8 resulted in male subfertility due to germ cell defects. However, this knockdown model was limited in examining the functions of Rhox8 as RHOX8 knockdown occurred only postnatally, and there was still residual RHOX8 in the testis. In this study, we generated new Rhox8 knockout (KO) mice using the CRISPR/Cas9 system. Sex determination and fetal testis development were apparently normal in mutant mice. Fertility analysis showed a low fecundity in Rhox8 KO adult males, with disrupted spermatogenic cycles, increased germ cell apoptosis, and reduced sperm count and motility. Interestingly, Rhox8 KO testes showed an increase in testis size with dilated seminiferous tubules and rete testis, which might be affected by efferent duct (ED) Rhox8 ablation dysregulating the expression of metabolism and transport genes in the EDs. Taken together, the data presented in this study suggest that Rhox8 in the Sertoli cells is not essential for sex determination and embryonic testis differentiation but has an important role in complete spermatogenesis and optimal male fertility.

A Rare Case of Precocious Puberty in a Child with a Novel GATA-4 Gene Mutation: Implications for Disorders of Sex Development (DSD) and Review of the Literature

BACKGROUND

Disorders/Differences of sex development (DSD) are often due to disruptions of the genetic programs that regulate gonad development. The GATA-4 gene, located on chromosome 8p23.1, encodes GATA-binding protein 4 (GATA-4), a transcription factor that is essential for cardiac and gonadal development and sexual differentiation.

CASE DESCRIPTION

A child with a history of micropenis and cryptorchidism. At 8 years of age, he came under our observation for an increase in sexual pubic hair (pubarche). The laboratory parameters and the GnRH test suggested a central precocious puberty (CPP). Treatment with GnRH analogs was started, and we decided to perform genetic tests for DSD. The NGS genetic investigation showed a novel and heterozygous variant in the GATA-4 gene.

DISCUSSION

In the literature, 26 cases with 46,XY DSD due to the GATA4 gene were reported.

CONCLUSION

The novel variant in the GATA-4 gene of our patient was not previously associated with DSD. This is the first case of a DSD due to a GATA-4 mutation that develops precocious puberty. Precocious puberty could be associated with DSD and considered a prelude to hypogonadism in some cases.

Targeted Disruption of Lats1 and Lats2 in Mice Impairs Testis Development and Alters Somatic Cell Fate

Hippo signaling plays an essential role in the development of numerous tissues. Although it was previously shown that the transcriptional effectors of Hippo signaling Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) can fine-tune the regulation of sex differentiation genes in the testes, the role of Hippo signaling in testis development remains largely unknown. To further explore the role of Hippo signaling in the testes, we conditionally deleted the key Hippo kinases large tumor suppressor homolog kinases 1 and -2 (Lats1 and Lats2, two kinases that antagonize YAP and TAZ transcriptional co-regulatory activity) in the somatic cells of the testes using an Nr5a1-cre strain (Lats1flox/flox;Lats2flox/flox;Nr5a1-cre). We report here that early stages of testis somatic cell differentiation were not affected in this model but progressive testis cord dysgenesis was observed starting at gestational day e14.5. Testis cord dysgenesis was further associated with the loss of polarity of the Sertoli cells and the loss of SOX9 expression but not WT1. In parallel with testis cord dysgenesis, a loss of steroidogenic gene expression associated with the appearance of myofibroblast-like cells in the interstitial space was also observed in mutant animals. Furthermore, the loss of YAP phosphorylation, the accumulation of nuclear TAZ (and YAP) in both the Sertoli and interstitial cell populations, and an increase in their transcriptional co-regulatory activity in the testes suggest that the observed phenotype could be attributed at least in part to YAP and TAZ. Taken together, our results suggest that Hippo signaling is required to maintain proper differentiation of testis somatic cells.

A Short Promoter Region Containing Conserved Regulatory Motifs Is Required for Steroidogenic Acute Regulatory Protein (Star) Gene Expression in the Mouse Testis

In the testis, Leydig cells produce steroid hormones that are needed to masculinize typical genetic males during fetal development and to initiate and maintain spermatogenesis at puberty and adulthood, respectively. Steroidogenesis is initiated by the transfer of cholesterol from the outer to the inner mitochondrial membrane through the action of steroidogenic acute regulatory protein (STAR). Given its importance for the steroidogenic process, the regulation of STAR gene expression has been the subject of numerous studies. These studies have involved the characterization of key promoter sequences through the identification of relevant transcription factors and the nucleotide motifs (regulatory elements) that they bind. This work has traditionally relied on in vitro studies carried out in cell cultures along with reconstructed promoter sequences. While this approach has been useful for developing models of how a gene might be transcriptionally regulated, one must ultimately validate that these modes of regulation occur in an endogenous context. We have used CRISPR/Cas9 genome editing to modify a short region of the mouse Star promoter (containing a subset of regulatory elements, including conserved CRE, C/EBP, AP1, and GATA motifs) that has been proposed to be critical for Star transcription. Analysis of the resultant mutant mice showed that this short promoter region is indeed required for maximal STAR mRNA and protein levels in the testis. Analysis also showed that both basal and hormone-activated testosterone production in mature mice was unaffected despite significant changes in Star expression. Our results therefore provide the first in vivo validation of regulatory sequences required for Star gene expression.