Paternal genetic effects of cadmium exposure during pregnancy on hormone synthesis disorders in ovarian granulosa cells of offspring.

The aim of this study was to investigate the paternal genetic intergenerational and transgenerational genetic effects of cadmium (Cd) exposure during pregnancy on estradiol (E2) and progesterone (Pg) synthesis in the ovarian granulosa cells (GCs) of offspring. Pregnant SD rats were intragastrically exposed to CdCl2 (0, 0.5, 2.0, 8.0 mg/kg) from days 1 to 20 to produce the F1 generation, F1 males were mated with newly purchased females to produce the F2 generation, and the F3 generation was obtained in the same way. Using this model, Cd-induced hormone synthesis disorders in GCs of F1 have been observed [8]. In this study, altered serum E2 and Pg levels in both F2 and F3 generations showed a nonmonotonic dose‒response relationship. In addition, hormone synthesis-related genes (Star, Cyp11a1, Cyp17a1, Cyp19a1, Sf-1) and miRNAs were observed to be altered in both F2 and F3. No differential changes in DNA methylation modifications of hormone synthesis-related genes were observed, and only the Adcy7 was hypomethylated. In summary, paternal genetic intergenerational and transgenerational effects exist in ovarian GCs E2 and Pg synthesis disorders induced by Cd during pregnancy. In F2, the upregulation of StAR and CYP11A1, and changes in the miR-27a-3p, miR-27b-3p, and miR-146 families may be important, while changes in the miR-10b-5p and miR-146 families in F3 may be important.

C-myc promotes miR-92a-2-5p transcription in rat ovarian granulosa cells after cadmium exposure.

Cadmium (Cd) can induce ovarian injury by microRNAs (miRNAs), however, the molecular mechanism of miRNAs after Cd exposure have not known. In this study, 56-day-old adult female Sprague-Dawley (SD) rats were injection with PMSG, after 48 h, ovarian granulosa cells (GCs) were extracted and cultured for 24 h, then treated with 0, 2.5, 5, 10 and 20 µM Cd for 24 h. The results showed that expression levels of miR-92a-2-5p (upregulated) and Bcl2 (downregulated) changed significantly after Cd exposure. The messenger RNA (mRNA) and protein expression levels of DNMT1, DNMT3A, and DNMT3B had changed, but no obvious differences were found in miR-92a-2-5p single site methylation. The transcription factors C-MYC (upregulated), E2F1 (downregulated), and SP1 (downregulated), which target miRNAs significantly changed after exposure to Cd. The human ovarian GC tumor line (COV434) was used to knocked down C-myc, and the expression of miR-92a-2-5p was downregulated in the COV434-C-myc + 10 µM Cd group compared with COV434 cells. The N6-methyladenosine (m6A) methylation modification levels of long noncoding RNA (lncRNA) MT1JP and lncRNA CDKN2B-AS, which regulate miR-92a-2-5p were detected. In the 10 µM Cd group, m6A methylation levels at MT1JP-84, CDKN2B-AS-257, and CDKN2B-AS-329 were reduced. In summary, after Cd exposure, expression of miR-92a-2-5p, which targets the antiapoptotic gene Bcl2, was upregulated, which may be primarily related to upregulation of C-myc. MiR-92a-2-5p promoter DNA methylation may has no obvious effect on miR-92a-2-5p. Otherwise, the role of m6A methylation modified lncRNA MT1JP and lncRNA CDKN2B-AS in the regulation of miR-92a-2-5p needs further study.