MiR-505-3p is a Repressor of the Puberty Onset in Female Mice miR-505-3p and the puberty onset

Abstract

24Puberty onset is a complex trait regulated by multiple genetic and environmental factors. In this 25 study, we narrowed a puberty related QTL down to a 1.7 Mb region on chromosome X in female mice 26 and inferred miR-505-3p as the functional gene. 27We conducted ectopic expression of miR-505-3p in the hypothalamus of prepubertal female mice 28 through lentivirus-mediated orthotopic injection. The impact of miR-505-3p on female puberty was 29 evaluated by the measurement of pubertal events and histological analysis. The results showed that 30 female mice with overexpression of miR-505-3p in the hypothalamus manifested later puberty onset 31 timing both in vaginal opening and ovary maturation, followed by weaker fertility lying in the longer 32 interval time between mating and delivery, higher abortion rate and smaller litter size. We also 33 constructed miR-505-3p knockout mice by CRISPR/Cas9 technology. MiR-505-3p knockout female 34 mice showed earlier vaginal opening timing, higher serum gonadotrophin and higher expression of 35 puberty-related gene, as well as its target gene Srsf1 in the hypothalamus than their wild type 36 littermates. 37Srsf1 was proved to be the target gene of miR-505-3p that played the major role in this process. 38The results of RIP-seq (RNA Immunoprecipitation-sequencing) showed that SF2, the protein product 39 of Srsf1 gene, mainly bound to ribosome protein (RP) mRNAs in GT1-7 cells. The collective evidence 40 implied that miR-505-3p/SRSF1/RP could play a role in the sexual maturation regulation of mammals. 41 Author summary 42 The puberty onset in mammals is a vital biological process that signals the acquisition of 43 reproductive capacity. The initiation of puberty is triggered by the activation of hypothalamic pulsatile 44 GnRH surge. The dysregulation of pubertal development shows relevance to later health risks of type 2 3 45 diabetes, cardiovascular disease, breast cancer and other health disorders. Recent progress indicates 46 that a lot of genes play a role in the excitatory or inhibitory regulation of GnRH release. However, the 47 detailed pathway of pubertal timing remains unclear. Our previous studies isolated an X-linked QTL 48that was associated with the timing of puberty in mice. In this study, we proved that miR-505-3p was a 49 female puberty onset regulator based on data from positional cloning, ectopic expression and knockout 50 mouse models. We also assigned Srsf1 as the functional target gene of miR-505-3p underlying this 51 process. The results of RIP-seq showed that SF2, the protein of Srsf1 gene, preferential bound to 52 ribosome protein (RP) mRNAs in GT1-7 cells. We propose that miR-505-3p/SF2/RP could play a role 53 in the sexual maturation regulation of mammals. 54