Transcription factors GATA-4 and GATA-6: molecular characterization, expression patterns and possible functions during goose (Anser cygnoides) follicle development

Molecular characterization, expression profile and transcriptional regulation of the CYP19 gene in goose ovarian follicles

Cytochrome P450 Family 19 (CYP19) is a crucial enzyme to catalyze the conversion of androgens to estrogens. However, the regulatory mechanism of goose CYP19 gene remains poorly understood. The present study attempted to obtain the full-length coding sequence (CDS) and 5'-flanking sequence of CYP19 gene, to investigate its expression and distribution profiles in different sized follicles, and to analyze the transcriptional regulatory mechanism of CYP19 gene in goose. Results showed that its CDS consisted of 1512 nucleotides and the encoded amino acid sequence contained a classical P450 structural domain. Homology analysis showed that there were high homologies of nucleotide and amino acid sequences between goose and other avian species. Its promoter sequence spanned from -1925 bp to the transcription start site (ATG) and several transcriptional factors were predicted in this region. Further analysis from luciferase assay showed that the luciferase activity was the highest spanning from -118 to -1 bp by constructing deletion promoter reporter vector. In addition, result from quantitative real-time polymerase chain reaction indicated that the mRNA level of CYP19 gene were highly expressed in theca layer of the fifth largest follicle, and the cellular location was in the theca externa cells by immunohistochemistry. Taken together, it could be concluded that the transcription activity of CYP19 gene was activated by transcriptional factors in its proximal region of promoter to promote the synthesis of estrogens, regulating the selection of pre-hierarchical into hierarchical follicle in goose.

Dynamics of the Transcriptome and Accessible Chromatin Landscapes During Early Goose Ovarian Development

In contrast to the situation in mammals, very little is known about the molecular mechanisms regulating early avian ovarian development. This study aimed to investigate the dynamic changes in the histomorphology as well as the genome-wide transcriptome and chromatin accessibility landscapes of the goose ovary during late embryonic and early post-hatching stages. Results from hematoxylin-eosin, periodic acid-Schiff, and anti-CVH immunohistochemical stainings demonstrated that programmed oocyte loss, oocyte nest breakdown and primordial follicle formation, and the primordial-to-secondary follicle transition occur during the periods from embryonic day 15 (E15) to post-hatching day 0 (P0), from P0 to P4, and from P4 to P28, respectively. RNA-seq and ATAC-seq analyses revealed dynamic changes in both the ovarian transcriptome and accessible chromatin landscapes during early ovarian development, exhibiting the most extensive changes during peri-hatching oocyte loss, and moreover, differences were also identified in the genomic distribution of the differential ATAC-seq peaks between different developmental stages, suggesting that chromatin-level regulation of gene expression is facilitated by modulating the accessibility of different functional genomic regions to transcription factors. Motif analysis of developmental stage-selective peak regions identified hundreds of potential cis-regulatory elements that contain binding sites for many transcription factors, including SF1, NR5A2, ESRRβ, NF1, and THRβ, as well as members of the GATA, SMAD, and LHX families, whose expression fluctuated throughout early goose ovarian development. Integrated ATAC-seq and RNA-seq analysis suggested that the number and genomic distribution of the newly appeared and disappeared peaks differed according to developmental stage, and in combination with qRT-PCR validation potentiated the critical actions of the DEGs enriched in cell cycle, MAPK signaling, and FoxO signaling pathways during peri-hatching oocyte loss and those in ligand-receptor interaction, tissue remodeling, lipid metabolism, and Wnt signaling during primordial follicle formation and development. In conclusion, our study provides a framework for understanding the transcriptome and accessible chromatin dynamics during early avian ovarian development and a new avenue to unravel the transcriptional regulatory mechanisms that facilitate the occurrence of relevant molecular events.

Promoter Identification and Transcriptional Regulation of the Goose AMH Gene

Simple Summary

Anti-Müllerian hormone (AMH) plays a vital role in the development of follicles. We found that the cloning nucleotide sequence of AMH was high homology in geese with other species. Several regulatory elements were identified and transcriptional factors were predicted in the AMH promoter sequence. Through a double-luciferase reporter assay, potential regulatory relationship spanning from −637 to −87 bp were identified. In addition, the mRNA expression of AMH gradually decreased during the development of follicles in geese. In the Chinese hamster ovary (CHO) cell line, the luciferase activity significantly increased by co-expression of AMH and GATA-4. However, when the binding sites of GATA-4 to the promoter of AMH were mutated, the luciferase activity significantly decreased. These results indicated that the transcription of AMH was activated by GATA-4 to inhibit the development of follicles in geese.

Abstract

Anti-Müllerian hormone (AMH) is recognized as a reliable marker of ovarian reserve. However, the regulatory mechanism of goose AMH gene remains poorly understood. In the present study, both the full-length coding sequence (CDS) and promoter sequence of goose AMH have been cloned. Its CDS consisted of 2013 nucleotides encoding 670 amino acids and the amino acid sequence contained two structural domain: AMH-N and transforming growth factor beta (TGF-β) domain. The obtained promoter sequence spanned from the −2386 bp to its transcription start site (ATG). Core promoter regions and regulatory elements were identified as well as transcription factors were predicted in its promoter sequence. The luciferase activity was the highest spanning from the −331 to −1 bp by constructing deletion promoter reporter vectors. In CHO cells, the luciferase activity significantly increased by co-expression of AMH and GATA binding protein 4 (GATA-4), while that significantly decreased by mutating the binding sites of GATA-4 located in the −778 and −1477 bp. Results from quantitative real-time polymerase chain reaction (qPCR) indicated that levels of AMH mRNA in geese granulosa layers decreased gradually with the increasing follicular diameter. Taken together, it could be concluded that the transcriptional activity of AMH was activated by GATA-4 to inhibit the development of small follicles in goose.

Roles of GATA6 during Gonadal Development in Japanese Flounder: Gonadogenesis, Regulation of Gender-Related Genes, Estrogen Formation and Gonadal Function Maintenance

GATA-binding protein 6 (GATA6), a highly-conserved transcription factor of the GATA family plays an important role in gonadal cell proliferation, differentiation and endoderm development. In this study, the full-length cDNA of GATA6 of Paralichthys olivaceus (Japanese flounder) was obtained. Phylogenetic, gene structure and synteny analyses demonstrated that GATA6 of P. olivaceus is homologous to that of teleosts and tetrapods. The P. olivaceus GATA6 transcript showed higher expression in testis than in ovary, demonstrating a sexually dimorphic gene expression. During embryonic development, the expression of P. olivaceus GATA6 increased at the blastula stage, demonstrating that GATA6 is involved in morphogenesis. Results of in situ hybridization showed that GATA6 signals were detected in Sertoli cells, oogonia and oocytes. Moreover, 17α methyl testosterone, a male hormone, could moderately upregulate P. olivaceus GATA6 and downregulate P. olivaceus aromatase CYP19A1 in testis cells. These results suggest that GATA6 may play an important role in gonadal development in P. olivaceus. This study provides valuable information on the function of P. olivaceus GATA6, laying the foundation for further development of breeding techniques in this species.

Regulator of G protein signaling 4 is a novel target of GATA-6 transcription factor

GATA transcription factors regulate an array of genes important in cell proliferation and differentiation. Here we report the identification of regulator of G protein signaling 4 (RGS4) as a novel target for GATA-6 transcription factor. Although three sites (a, b, c) within the proximal region of rabbit RGS4 promoter for GATA transcription factors were predicted by bioinformatics analysis, only GATA-a site (16 bp from the core TATA box) is essential for RGS4 transcriptional regulation. RT-PCR analysis demonstrated that only GATA-6 was highly expressed in rabbit colonic smooth muscle cells but GATA-4/6 were expressed in cardiac myocytes and GATA-1/2/3 expressed in blood cells. Adenovirus-mediated expression of GATA-6 but not GATA-1 significantly increased the constitutive and IL-1β-induced mRNA expression of the endogenous RGS4 in colonic smooth muscle cells. IL-1β stimulation induced GATA-6 nuclear translocation and increased GATA-6 binding to RGS4 promoter. These data suggest that GATA factor could affect G protein signaling through regulating RGS4 expression, and GATA signaling may develop as a future therapeutic target for RGS4-related diseases.

Molecular characterization and expression profiles of GATA6 in tongue sole (Cynoglossus semilaevis)

GATA-binding protein 6 (GATA6), a transcription factor of the GATA family, plays an important role in gonadal cell proliferation, differentiation, and endoderm development. In this study, the full-length coding sequence of tongue sole (Cynoglossus semilaevis) GATA6 was identified. The sequence consisted of 1494 nucleotides encoding a peptide of 497 amino acids, which included two conserved zinc finger domains. Phylogenetic, gene structure, and synteny analysis showed that C. semilaevis GATA6 was homologous to teleost and tetrapod GATA6. C. semilaevis GATA6 mRNA exhibited high expression in heart, intestine, liver, kidney, and gonad. Embryonic development expression profiles revealed that GATA6 is involved in morphogenesis because its expression increased at the blastula stage. The in situ hybridization results showed strong GATA6 signals in spermatogonia, spermatocytes, and Sertoli cells of the testis. The signals were also detected in the oogonia and oocytes of the ovary. The expression of C. semilaevis GATA6 was sexually dimorphic, and the methylation pattern in the promoter region varied among males, females, and pseudomales. These results suggested that GATA6 might influence the gonad development and reproduction of C. semilaevis. This study provides the groundwork for further development of breeding techniques in C. semilaevis.