Genetic expression of Zinc transporters in the cummulus-oocyte complex: influence of three reproductive hormones

PASCUA AM; QUINTANA S; NIKILOFF N,; SIRINI MA; ANCHORDOQUY JP; ANCHORDOQUY JM; FURNUS C

Congreso; 3. 3° Congreso Internacional de la Sociedad Argentina de Tecnologías Embrionarias; 2016

Zinc (Zn) is involved in a wide variety of cellular processes and its availability influences many reproductive events and the embryonic development. However, little is known of the mechanisms regulating Zn homeostasis in the cummulus-oocyte complex (COC) and other cellular types of the reproductive system. In order to assess the Zn transport through the cell, analyzing the genetic expression of this micronutrient?s transporters becomes essential. In this regard, mRNA expression of four Zn transporters (ZIP 6 and Znt 3, 7 and 9) was evaluated in bovine oocytes and cummulus cells under the influence of three reproductive hormones: oestradiol (E2), follicle stimulating hormone (FSH) and luteinizing hormone (LH). To that end, COCs were in vitro maturated for 24 hours including the following treatments: (1a) hormonal supplementation (E2 1µg/ml, FSH 1 µg/ml, LH 10 µg/ml) plus addition of Zn 120 ug/dl (regular concentration) and (1b) hormonal supplementation only. Maturation controls without hormones were included: (2a) with Zn supplementation, (2b) without Zn supplementation. Subsequently, RNA was extracted, digested with DNAase and assessed for presence or absence of mARN in oocytes and cummulus cells using RT-PCR. The results show, for the first time, that mRNA from transporters ZIP 6 and Znt 9 is expressed in the bovine oocyte, while cummulus cells show expression of Znt 9 and 3. In neither evaluated cell type was Znt 7 mRNA detected. The expression results for each treatment and cell kind are displayed below: Cell typeT=0 of maturationHormonal suplementation No hormonal suplementationwith Znwithout Znwith Znwithout ZnZip6Oocytes+-+++Cummulus-----Znt3Oocytes-----Cummulus-+-+-Znt7Oocytes-----Cummulus-----Znt9Oocytes---++Cummulus-+---In conclusion, in regard to the oocytes, no expression of ZIP 6 was detected after zinc plus hormones addition in the maturation process, while Znt 9 showed no mRNA under hormonal supplementation in absence and presence of this mineral. Furthermore, with respect to cummulus cells, Znt 9 revealed no expression under either case of hormonal inclusion, while Znt 3 did not manifest expression in the cases without zinc. It is noteworthy the mRNA detection for ZIP 6 in the pre-maturation oocyte. Although further in-depth expression studies need to be conducted with differentiation of each added hormone, these dissimilarities suggest that reproductive hormones influence the genetic expression of the evaluated zinc transporters.