Abstract
Luteinizing hormone (LH) plays a key role in the control of physiological processes such as follicle development, ovulation and luteal maintenance in the ovary acting via, LHR. The LHR expression in bovine granulosa cells is crucial for the transition of FSH/LH-dependency in antral follicles. In cattle during the growth and differentiation of granulosa cells, there is an increase on LHR mRNA abundance. Among several factors that control the ovarian development, there is an involvement of microRNAs (miRNAs). MiRNAs are small no-coding RNA molecules composed by 19-25 base pairs that control the cellular translation. Studies have characterized the presence and dual actions of miRNAs in mammalian female reproductive tract, including, deleterious effects on female fertility, as the reduction in ovulatory capacity. Inversely, there is a pro-follicular effect, as inhibition of apoptosis in ovarian follicular by in vivo administration of miRNAs. Recent data has showed miRNAs that regulate LHR expression in rodents. In cattle, some studies have identified the profile of miRNAs expressed in adult and fetal ovaries and characterized the regulatory effect of miRNAs on mRNA targets involved in ovarian follicular differentiation, but not in the context aimed in this work. Thus, this project using four experiments, aims to investigate and characterize the profile of miRNAs expressed in granulosa cells during follicle deviation in Nelore heifers and controller of LHR mRNA expression, as well as its regulation by pro-survival factors for follicles (IGF1) and gonadotropins (FSH and eCG) used in pharmacological strategies for control of the estrous cycle in cattle. Additionally, we intend to evaluate in vitro actions of miRNAs on the regulation of LHR expression and consequently on the steroidogenesis of granulosa cells. Therefore, it is expected that the compilation of the results generated by this study may be identify new targets for enhanced reproductive efficiency in cattle different pharmacological on strategies for the manipulation of the estrus cycle, producing a "molecular signature" of miRNAs required for the development of the follicle dominant in Nellore females, stimulating, perhaps, the development of molecular therapies through the use of miRNAs (in situ) to post transcriptional regulation in the bovine ovary in females of low fertility. (AU)
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