GLP-1: a novel zinc finger protein required in somatic cells of the gonad for germ cell development

Zglp-1 is a novel essential transcriptional regulator for sex reversal in zebrafish

Sex determination and differentiation play crucial biological roles in sexual reproduction in vertebrates, including zebrafish. Nevertheless, the intricate molecular mechanisms governing these processes have remained enigmatic. In this study, we showed a pivotal role played by zinc finger GATA-like protein-1 (Zglp-1) in sex differentiation in zebrafish. Our findings revealed that homozygous mutants having no Zglp-1 exhibited a female-to-male sex reversal, ultimately resulting in the development of fertile males. Within the pivotal phase of sexual differentiation, zglp-1 -/- zebrafish demonstrated a gene expression pattern that was skewed toward a male phenotype. Notably, the expression of amh was upregulated, while the expression of cyp19a1a was not sustained. Furthermore, our data revealed a direct interaction between the zinc fingers of Zglp-1 and Sf-1, which inhibited the ability of Sf-1 to activate the amh promoter. This interaction was crucial for regulating sex differentiation. Moreover, we observed alterations in gonadal cell proliferation and apoptosis in zglp-1 -/- zebrafish, which partially contributed to the sexual fate selection. Overall, our findings firmly established Zglp-1 as a crucial regulator of sex differentiation in zebrafish, offering deep insights into the intricate molecular mechanisms that govern sex determination and differentiation in vertebrates.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-025-00299-5.

Prescribing semaglutide for weight loss in non-diabetic, obese patients is associated with an increased risk of erectile dysfunction: a TriNetX database study

Semaglutide was approved in June 2021 for weight loss in non-diabetic, obese patients. While package inserts include sexual dysfunction as a side effect, no study has assessed the degree of this risk. The objective of our study is to assess the risk of developing erectile dysfunction after semaglutide is prescribed for weight loss in obese, non-diabetic men. The TriNetX Research database was used to identify men without a diagnosis of diabetes ages 18 to 50 with BMI > 30 who were prescribed semaglutide after June 1st, 2021. Men were excluded if they had a prior erectile dysfunction diagnosis, any phosphodiesterase-5 inhibitors prescription, intracavernosal injections, penile prosthesis placement, history of testosterone deficiency, testosterone prescription, pelvic radiation, radical prostatectomy, pulmonary hypertension, or were deceased. We further restricted our cohort to non-diabetic, obese men by excluding men with a prior diabetes mellitus diagnosis, a hemoglobin A1c > 6.5%, or having ever received insulin or metformin. Men were then stratified into cohorts of those that did and did not receive a semaglutide prescription. The primary outcome was the risk of new ED diagnosis and/or new prescription of phosphodiesterase type 5 inhibitors at least one month after prescription of semaglutide. The secondary outcome was risk of testosterone deficiency diagnosis. Risk was reported using risk ratios with 95% confidence intervals (95% CI). 3,094 non-diabetic, obese men ages 18-50 who received a prescription of semaglutide were identified and subsequently matched to an equal number cohort of non-diabetic, obese men who never received a prescription of semaglutide. After matching, average age at index prescription for non-diabetic, obese men was 37.8 ± 7.8 and average BMI at index prescription was 38.6 ± 5.6. Non-diabetic men prescribed semaglutide were significantly more likely to develop erectile dysfunction and/or were prescribed phosphodiesterase type 5 inhibitors (1.47% vs 0.32%; RR: 4.5; 95% CI [2.3, 9.0]) and testosterone deficiency (1.53% vs 0.80%; RR: 1.9; 95% CI [1.2, 3.1]) when compared to the control cohort of non-diabetic men who never received a semaglutide prescription.

Is there a role for glucagon-like peptide-1 receptor agonists in the treatment of male infertility?

Glucagon‐like peptide‐1 receptor agonists (GLP1‐RAs) are novel anti‐hyperglycemic drugs efficacious on glucose control, weight loss, and cardiovascular prevention. These drugs may also be effective in modulating testicular function. In fact, they increase serum testosterone levels in diabetic and/or obese patients with functional hypogonadism on a dysmetabolic basis. Although part of this effect can be ascribed to weight loss, some evidence suggests that there is a direct effect at the testicular level. Indeed, human Leydig, Sertoli, and germ cells express GLP1 receptors. GLP1‐RAs improve sperm metabolism, motility, and insulin secretion in vitro. Likewise, GLP1‐RAs exert positive effects on the metabolism of human Sertoli cells in vitro. Finally, GLP1 is secreted by mouse Leydig cells and this suggests the presence of a paracrine mechanism by which these cells could support the metabolism of Sertoli cells. Therefore, the widespread use of GLP1‐RAs in clinical practice may reveal an important role in the management of male infertility in obese and/or diabetic patients given the negative impact of these diseases on testicular steroidogenesis and spermatogenesis. This should suggest the design of randomized controlled studies aimed at evaluating the effects of these drugs on testicular function.

ZGLP1 is a determinant for the oogenic fate in mice

Sex determination of germ cells is vital to creating the sexual dichotomy of germ cell development, thereby ensuring sexual reproduction. However, the underlying mechanisms remain unclear. Here, we show that ZGLP1, a conserved transcriptional regulator with GATA-like zinc fingers, determines the oogenic fate in mice. ZGLP1 acts downstream of bone morphogenetic protein, but not retinoic acid (RA), and is essential for the oogenic program and meiotic entry. ZGLP1 overexpression induces differentiation of in vitro primordial germ cell-like cells (PGCLCs) into fetal oocytes by activating the oogenic programs repressed by Polycomb activities, whereas RA signaling contributes to oogenic program maturation and PGC program repression. Our findings elucidate the mechanism for mammalian oogenic fate determination, providing a foundation for promoting in vitro gametogenesis and reproductive medicine.

A Hormone That Lost Its Receptor: Anti-Müllerian Hormone (AMH) in Zebrafish Gonad Development and Sex Determination

Fetal mammalian testes secrete Anti-Müllerian hormone (Amh), which inhibits female reproductive tract (Müllerian duct) development. Amh also derives from mature mammalian ovarian follicles, which marks oocyte reserve and characterizes polycystic ovarian syndrome. Zebrafish (Danio rerio) lacks Müllerian ducts and the Amh receptor gene amhr2 but, curiously, retains amh To discover the roles of Amh in the absence of Müllerian ducts and the ancestral receptor gene, we made amh null alleles in zebrafish. Results showed that normal amh prevents female-biased sex ratios. Adult male amh mutants had enormous testes, half of which contained immature oocytes, demonstrating that Amh regulates male germ cell accumulation and inhibits oocyte development or survival. Mutant males formed sperm ducts and some produced a few offspring. Young female mutants laid a few fertile eggs, so they also had functional sex ducts. Older amh mutants accumulated nonvitellogenic follicles in exceedingly large but sterile ovaries, showing that Amh helps control ovarian follicle maturation and proliferation. RNA-sequencing data partitioned juveniles at 21 days postfertilization (dpf) into two groups that each contained mutant and wild-type fish. Group21-1 upregulated ovary genes compared to Group21-2, which were likely developing as males. By 35 dpf, transcriptomes distinguished males from females and, within each sex, mutants from wild types. In adult mutants, ovaries greatly underexpressed granulosa and theca genes, and testes underexpressed Leydig cell genes. These results show that ancestral Amh functions included development of the gonadal soma in ovaries and testes and regulation of gamete proliferation and maturation. A major gap in our understanding is the identity of the gene encoding a zebrafish Amh receptor; we show here that the loss of amhr2 is associated with the breakpoint of a chromosome rearrangement shared among cyprinid fishes.

Expression analysis and characterization of zglp1 in the Chinese tongue sole (Cynoglossus semilaevis)

Zinc finger GATA like protein-1 (ZGLP1) is a nuclear zinc finger protein that regulates the interaction between somatic cells and germ cells during gonad developmental process in mammals. In this study, the zglp1 of Chinese tongue sole, Cynoglossus semilaevis (cysezglp1), was cloned and characterized for the first time in fish. Cysezglp1 had an open reading frame with five exons and was located to chromosome 9. The open reading frame of cysezglp1 consisted of 1692 nucleotides and encoded a 583 amino acid polypeptide. The predicted protein contained two zinc finger structures (Znf1 and Znf2), one of which was highly homologous to the GATA-type zinc finger domain. Multiple sequence alignment showed that Znf1 was conserved across different species while Znf2 was more divergent. Through quantitative Real-time PCR (qRT-PCR), we found that cysezglp1 was predominantly expressed in gonads, and the expression level of the ovary was significantly higher than that of the testis. We compared expression level in different embryonic stages and found that cysezglp1 mRNAs were mainly expressed in the fertilized egg to the cleavage stage, subsequently declining in the blastula stage. Cysezglp1 expression was not detected from the gastrulation stage onward. In the ovary, cysezglp1 expression was detected at 120 days after hatching and expression gradually increased with the maturation of the ovary. In situ hybridization showed that the cysezglp1 was mainly expressed in oocytes. Taken together, our results suggest that cysezglp1 may play an important role in the process of oogenesis in Chinese tongue sole.

A novel GATA-like zinc finger transcription factor involving in hematopoiesis of Eriocheir sinensis

GATA transcription factor is a family of DNA-binding proteins that can recognize and bind to sequence of (A/T) GATA (A/G). In the present study, a GATA-like protein (named as EsGLP) was characterized from Eriocheir sinensis, including an 834 bp full length open reading frame of EsGLP, encoding a polypeptide of 277 amino acids. The deduced amino acid sequence of EsGLP contained one conserved GATA-type zinc finger of the form Cys-X2-Cys-X17-Cys-X2-Cys, with four cysteine sites. The EsGLP mRNA transcripts were mainly detected in the hematopoietic tissue, hepatopancreas and gonad. The recombinant EsGLP protein was prepared for the antibody production. The EsGLP protein was mainly distributed in the edge of lobules in the HPT and the cytoplasm of hemocytes. The mRNA transcripts of EsGLP in hemocytes were significantly decreased at 24 h (0.39-fold and 0.27-fold, p < .05) and 48 h (0.35-fold and 0.16-fold, p < .05) after LPS and Aeromonas hydrophila stimulation, respectively. However, one peak of EsGLP mRNA transcripts were recorded at 24 h (8.71-fold, p < .05) in HPT after A. hydrophila stimulation. The expression level of EsGLP mRNA in HPT was significantly up-regulated at 2 h, 2.5 h and 9 h (41.74-fold, 45.38-fold and 26.07-fold, p < .05) after exsanguination stimulation. When EsGLP gene expression was inhibited by the injection of double-stranded RNA, both the total hemocytes counts and the rate of EdU-positive hemocytes were significantly decreased (0.32-fold and 0.56-fold compared to that in control group, p < .05). All these results suggested that EsGLP was an important regulatory factor in E. sinensis which involved in the hemocytes generation and the immune response against invading pathogens.

Polarity Protein Scrib Facilitates Endothelial Inflammatory Signaling

OBJECTIVE

The polarity protein Scrib is highly expressed in endothelial cells and is required for planar cell polarity. Scrib also facilitates recycling of integrin α5 to the plasma membrane. Because integrin α5 signals the presence of the inflammatory matrix protein fibronectin, we hypothesized that Scrib contributes to endothelial inflammatory signaling.

APPROACH AND RESULTS

Cytokine treatment of human umbilical vein endothelial cells induced an inflammatory response as evident by the induction of vascular cell adhesion molecule-1 (VCAM-1). Downregulation of Scrib greatly attenuated this effect. In endothelial-specific conditional Scrib knockout mice, in vivo lipopolysaccharide treatment resulted in an impaired VCAM-1 induction. These effects were functionally relevant because Scrib small interfering RNAs in human umbilical vein endothelial cells attenuated the VCAM-1-mediated leukocyte adhesion in response to tumor necrosis factor-α. In vivo, tamoxifen-induced endothelial-specific deletion of Scrib resulted in a reduced VCAM-1-mediated leukocyte adhesion in response to tumor necrosis factor-α in the mouse cremaster model. This effect was specific for Scrib and not mediated by other polarity proteins. Moreover, it did not involve integrin α5 or classic pathways supporting inflammatory signaling, such as nuclear factor κ light chain enhancer of activated B-cells or MAP kinases. Co-immunoprecipitation/mass spectrometry identified the zinc finger transcription factor GATA-like protein-1 as a novel Scrib interacting protein. Small interfering RNA depletion of GATA-like protein-1 decreased the tumor necrosis factor-α-stimulated VCAM-1 induction to a similar extent as loss of Scrib did. Silencing of Scrib reduced GATA-like protein-1 protein, but not mRNA abundance.

CONCLUSIONS

Scrib is a novel proinflammatory regulator in endothelial cells, which maintains the protein expression of GATA-like protein-1.

Early depletion of primordial germ cells in zebrafish promotes testis formation

As complete absence of germ cells leads to sterile males in zebrafish, we explored the relationship between primordial germ cell (PGC) number and sexual development. Our results revealed dimorphic proliferation of PGCs in the early zebrafish larvae, marking the beginning of sexual differentiation. We applied morpholino-based gene knockdown and cell transplantation strategies to demonstrate that a threshold number of PGCs is required for the stability of ovarian fate. Using histology and transcriptomic analyses, we determined that zebrafish gonads are in a meiotic ovarian stage at 14 days postfertilization and identified signaling pathways supporting meiotic oocyte differentiation and eventual female fate. The development of PGC-depleted gonads appears to be restrained and delayed, suggesting that PGC number may directly regulate the variability and length of gonadal transformation and testicular differentiation in zebrafish. We propose that gonadal transformation may function as a developmental buffering mechanism to ensure the reproductive outcome.

Oogenesis: transcriptional regulators and mouse models

Oocyte differentiation into a totipotent cell requires initial germ cell cyst breakdown to form primordial follicles, recruitment of primordial follicles for development into primary follicles and remarkable growth of the ovarian follicle which culminates in ovulation. During oogenesis, the oocyte undergoes dynamic alterations in gene expression which are regulated by a set of well-coordinated transcription factors active in the germ line and soma. A number of germ cell specific as well as somatic expressed transcriptional regulators are critical in ovarian formation and folliculogenesis. These transcriptional regulators include: Foxo3, Foxl2, Figla, Lhx8, Nobox, Sohlh1 and Sohlh2. A subset of these transcriptional regulators is mutated in women with ovarian insufficiency and infertility. Studies on transcriptional regulators preferentially expressed in the ovary are important to develop a better understanding of the mechanisms of activation and survival of ovarian follicles, as well as an understanding of ovary specific pathways that can be modulated in the future to regulate fertility and protect against external insults such as chemotherapy.

GATA-like protein-1 (GLP-1) is required for normal germ cell development during embryonic oogenesis

Oogenesis and primordial follicle formation are tightly linked processes, requiring organized and precisely timed communication between somatic and germ cells. Deviations in ovarian cell cross talk, or aberrant gene expression within one of the cell populations, can lead to follicle loss or dysfunction, resulting in infertility. Expression of GATA-like protein-1 (GLP-1) in ovarian somatic cells is required for normal fertility in female mice, as GLP-1 deficiency leads to the absence of oocytes at birth. However, the timing and nature of this germ cell loss is not well understood. In this study, we characterize the embryonic germ cell loss in GLP-1 null mice. Quantitative PCR demonstrates that ovarian Glp-1 mRNA is expressed in a bimodal pattern during embryogenesis, peaking at E13.5–14.5 and again at birth. In contrast, adult ovaries express low but detectable levels of Glp-1 mRNA. Analysis of developing GLP-1 null mouse ovaries shows that germ cells are appropriately specified and migrate normally to nascent gonads. Upon arrival at the gonad, precocious loss of germ cells begins at around E13.5. This loss is completed by birth and is accompanied by defects in the expression of genes associated with meiotic entry. Interestingly, somatic pregranulosa cells still form basement membranes surrounding germ line cysts and express mRNA encoding paracrine signaling molecules that communicate with oocytes, albeit at lower levels than normal. Together, these data imply that the somatic cell protein GLP-1 is not necessary for many pregranulosa cell functions but is required for germ cell survival.

Role of the GATA family of transcription factors in endocrine development, function, and disease

The WGATAR motif is a common nucleotide sequence found in the transcriptional regulatory regions of numerous genes. In vertebrates, these motifs are bound by one of six factors (GATA1 to GATA6) that constitute the GATA family of transcriptional regulatory proteins. Although originally considered for their roles in hematopoietic cells and the heart, GATA factors are now known to be expressed in a wide variety of tissues where they act as critical regulators of cell-specific gene expression. This includes multiple endocrine organs such as the pituitary, pancreas, adrenals, and especially the gonads. Insights into the functional roles played by GATA factors in adult organ systems have been hampered by the early embryonic lethality associated with the different Gata-null mice. This is now being overcome with the generation of tissue-specific knockout models and other knockdown strategies. These approaches, together with the increasing number of human GATA-related pathologies have greatly broadened the scope of GATA-dependent genes and, importantly, have shown that GATA action is not necessarily limited to early development. This has been particularly evident in endocrine organs where GATA factors appear to contribute to the transcription of multiple hormone-encoding genes. This review provides an overview of the GATA family of transcription factors as they relate to endocrine function and disease.

Regulation of Kruppel-like factor 4, 9, and 13 genes and the steroidogenic genes LDLR, StAR, and CYP11A in ovarian granulosa cells

Kruppel-like factors (KLFs) are important Sp1-like eukaryotic transcriptional proteins. The LDLR, StAR, and CYP11A genes exhibit GC-rich Sp1-like sites, which have the potential to bind KLFs in multiprotein complexes. We now report that KLF4, KLF9, and KLF13 transcripts are expressed in and regulate ovarian cells. KLF4 and 13, but not KLF9, mRNA expression was induced and then repressed over time (P < 0.001). Combined LH and IGF-I stimulation increased KLF4 mRNA at 2 h (P < 0.01), whereas LH decreased KLF13 mRNA at 6 h (P < 0.05), and IGF-I reduced KLF13 at 24 h (P < 0.01) compared with untreated control. KLF9 was not regulated by either hormone. Transient transfection of KLF4, KLF9, and KLF13 suppressed LDLR/luc, StAR/luc, and CYP11A/luc by 80-90% (P < 0.001). Histone-deacetylase (HDAC) inhibitors stimulated LDLR/luc five- to sixfold and StAR/luc and CYP11A/luc activity twofold (P < 0.001) and partially reversed suppression by all three KLFs (P < 0.001). Deletion of the zinc finger domain of KLF13 abrogated repression of LDLR/luc. Lentiviral overexpression of the KLF13 gene suppressed LDLR mRNA (P < 0.001) and CYP11A mRNA (P = 0.003) but increased StAR mRNA (P = 0.007). Collectively, these data suggest that KLFs may recruit inhibitory complexes containing HDAC corepressors, thereby repressing LDLR and CYP11A transcription. Conversely, KLF13 may recruit unknown coactivators or stabilize StAR mRNA, thereby explaining enhancement of in situ StAR gene expression. These data introduce new potent gonadal transregulators of genes encoding proteins that mediate sterol uptake and steroid biosynthesis.

GATA elements control repression of cardiac troponin I promoter activity in skeletal muscle cells

Background

We reported previously that the cardiac troponin I (cTnI) promoter drives cardiac-specific expression of reporter genes in cardiac muscle cells and in transgenic mice, and that disruption of GATA elements inactivates the cTnI promoter in cultured cardiomyocytes. We have now examined the role of cTnI promoter GATA elements in skeletal muscle cells.

Results

Mutation or deletion of GATA elements induces a strong transcriptional activation of the cTnI promoter in regenerating skeletal muscle and in cultured skeletal muscle cells. Electrophoretic mobility shift assays show that proteins present in nuclear extracts of C2C12 muscle cells bind the GATA motifs present in the cTnI promoter. However, GATA protein complex formation is neither reduced nor supershifted by antibodies specific for GATA-2, -3 and -4, the only GATA transcripts present in muscle cells.

Conclusion

These findings indicate that the cTnI gene promoter is repressed in skeletal muscle cells by GATA-like factors and open the way to further studies aimed at identifying these factors.