Gene Expression of Takifugu rubripes Gonads During AI- or MT-induced Masculinization and E2-induced Feminization.

Elucidating the global molecular changes that occur during aromatase inhibitor (AI)- or 17α-methyltestosterone (MT)-induced masculinization and estradiol-17ß (E2)-induced feminization is critical to understanding the roles that endocrine and genetic factors play in regulating the process of sex differentiation in fish. Here, fugu larvae were treated with AI (letrozole), MT, or E2 from 25 to 80 days after hatching (dah), and gonadal transcriptomic analysis at 80 dah was performed. The expression of dmrt1, gsdf, foxl2, and other key genes (star, hsd3b1, cyp11c1, cyp19a1a, etc.) involved in the steroid hormone biosynthesis pathway were found be altered. The expression of dmrt1, gsdf, cyp19a1a, and foxl2 was further verified by quantitative polymerase chain reaction. In the control group, the expression of dmrt1 and gsdf was significantly higher in XY larvae than in XX larvae, while the expression of foxl2 and cyp19a1a was significantly higher in XX larvae than in XY larvae (P < .05). AI treatment suppressed the expression of foxl2 and cyp19a1a, and induced the expression of dmrt1 and gsdf in XX larvae. MT treatment suppressed the expression of foxl2, cyp19a1a, dmrt1, and gsdf in XX larvae. E2 treatment suppressed the expression of dmrt1 and gsdf, but did not restore the expression of foxl2 and cyp19a1a in XY larvae. The shared response following AI, MT, and E2 treatment suggested that these genes are essential for sex differentiation. This finding offers some insight into AI or MT-induced masculinization, and E2-induced femininization in fugu.

FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants.

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation.

Molecular cloning of ESR1, BMPR1B, and FOXL2 and differential expressions depend on maternal age and size during breeding season in cultured Asian yellow pond turtle (Mauremys mutica).

The reproductive capacity (egg size and egg number) of most of oviparous animals, including the Asian yellow pond turtle (Mauremys mutica), is constrained by the maternal age and body size, but the mechanism determining the maternal reproductive ability remains unclear. To disclose how maternal age and size affect reproductive ability of M. mutica, we first identified the full-length cDNAs from estrogen receptor 1 (ESR1), bone morphogenetic protein receptor 1B (BMPR1B), and forkhead box L2 (FOXL2). The ESR1 open reading frame (ORF) was 1, 767 bp encoding 588 amino acids. For BMPR1B, the ORF was 1599 bp encoding 532 amino acids, and an ORF of 906 bp encoding 301 amino acids was identified in FOXL2. The effects of maternal age and size on the expression of ESR1, BMPR1B, and FOXL2 in the ovary, brain, and uterus showed that ESR1 expression in large females was significantly lower than that in small females in the brain, but body size did not affect ESR1 expression in the ovary. The expression of ESR1 was significantly different in the different age groups and size groups, and there was interaction detected between maternal age and body size. However, BMPR1B expression in the ovary, brain, and uterus was independent of maternal age and size. In addition, we found different FOXL2 expression patterns between the brain and uterus, while detected interaction of female age and size in the brain and ovary. Our results imply the complexity and diversity of maternal age and size in regulating the expression of genes related to reproduction. These results provide more information for the maternal effects on the reproduction-related gene expression.

Logical modelling uncovers developmental constraints for primary sex determination of chicken gonads.

In the chicken, sex determination relies on a ZZ (male)/ZW (female) chromosomal system, but underlying mechanisms are still not fully understood. The Z-dosage and the dominant W-chromosome hypotheses have been proposed to underlie primary sex determination. We present a modelling approach, which assembles the current knowledge and permits exploration of the regulation of this process in chickens. Relying on published experimental data, we assembled a gene network, which led to a logical model that integrates both the Z-dosage and dominant W hypotheses. This model showed that the sexual fate of chicken gonads results from the resolution of the mutual inhibition between DMRT1 and FOXL2, where the initial amount of DMRT1 product determines the development of the gonads. In this respect, at the initiation step, a W-factor would function as a secondary device, by reducing the amount of DMRT1 in ZW gonads when the sexual fate of the gonad is settled, that is when the SOX9 functional level is established. Developmental constraints that are instrumental in this resolution were identified. These constraints establish qualitative restrictions regarding the relative transcription rates of the genes DMRT1, FOXL2 and HEMGN. Our model further clarified the role of OESTROGEN in maintaining FOXL2 function during ovary development.

Correlation of FOXL2 with Inhibin and Calretinin in the Diagnosis of Ovarian Sex Cord Stromal Tumors.

OBJECTIVE: Alpha-inhibin and calretinin have been traditionally used as immunomarkers for sex cord stromal tumors. However, the variation in their immunoreactivity and their lack of specificity for sex cord stromal tumor makes the search for a more sensitive and specific immunohistochemical marker essential in routine diagnosis of sex cord stromal tumor. This study was conducted to correlate the diagnostic utility of FOXL2 with inhibin and calretinin in the diagnosis of sex cord stromal tumors of ovary. MATERIAL AND METHOD: The study was conducted in the department of pathology. 31 cases of sex cord tumors received in past eight years (2002-2010) were included in this study. Immunostaining for inhibin, calretinin and FOXL2 was performed and compared on the basis of staining intensity and percentage positivity on all the cases. RESULTS: Calretinin was found to be positive in 29/31 sex cord stromal tumors with variable intensities and was negative in two cases of sex cord stromal tumors, inhibin was positive in 28/31 and only three cases had no cytoplasmic staining. All the 31 cases included in this study were positive for FOXL2 with variable staining intensities and percentage positivity. Ten cases of each surface epithelial and germ cell tumors were also negatively stained with FOXL2. CONCLUSION: In contrast to inhibin and calretinin, FOXL2 had a sensitivity and specificity of 100% for all the cases of sex cord stromal tumors included in this study.