Nutritional status affects the microRNA profile of the hypothalamus of female sheep

Abstract

Recent studies on the seasonal regulation of the oestrous cycle in sheep have focussed mainly on the responses to photoperiod. However, the brain systems that control reproductive activity also respond to nutritional inputs, although the molecular mechanisms involved are not completely understood. One possibility is that small, non-coding RNAs, such as micro-RNAs (miRNAs), have significant influence. In the present study, the amounts and characteristics of miRNAs in hypothalamus from oestrous and anestrous ewes, fed low- or high-nutrient diets, were compared using Illumina HiSeq sequencing technology. In total, 398 miRNAs, including 261 novel miRNAs, were identified in ewes with an enhanced nutritional status (HEN), whereas 384 miRNAs, including 247 novel miRNAs, were identified in the ewes with a lesser nutritional status (HAN). There were eight conserved and 140 novel miRNAs expressed differentially between the two libraries. Based on quantitative real-time polymerase chain reaction, six miRNAs were assessed to verify the accuracy of the library database. Moreover, the correlation between the miRNA target and several upstream and downstream genes in the oestrus-related pathways were also verified in hypothalamus nerve cells. According to the results, nutritional status plays an important role in oestrous regulation in sheep, and the hypothalamic processes and pathways induced by nutritional signals (folic acid and tyrosine) are different from those induced by photoperiodic regulation of oestrus. We have expanded the repertoire of sheep miRNAs that could contribute to the molecular mechanisms that regulate the initiation of oestrous cycles in anestrous ewes in response to the influence of nutritional status.

The effect of GNAQ methylation on GnRH secretion in sheep hypothalamic neurons

“…Studies have found that Kiss1R can transmit signals through Gαq/11, thereby regulating GnRH secretion . Our research has shown that downregulation of GnAQ expression causes the upregulation of a series of estrous‐related genes; this regulatory mechanism may be different from the regulatory mechanism of the photoperiod; GPR54/Kiss are expressed on GnRH and kisspeptin neurons in the hypothalamus and simultaneously belong to the upstream genes of GnAQ in the GnRH signaling pathway, which are also major regulators of the HPG axis, consistent with the results of this study. In the GnRH signaling pathway, GnAQ acts as a downstream gene of the GnRH receptor and is directly affected by this receptor; the downstream genes of PLC and PRKCB can combine with nerve calcium‐regulating protein inhibitors, leading to renal insufficiency .…”

“…B, Blsulfite modifications of DNA compared to initial nuclaotide sequences. C, Sequencing results photoperiod 12 ; GPR54/Kiss are expressed on GnRH and kisspeptin neurons in the hypothalamus and simultaneously belong to the upstream genes of GnAQ in the GnRH signaling pathway, which are also major regulators of the HPG axis, consistent with the results of this study. In the GnRH signaling pathway, GnAQ acts as a downstream gene of the GnRH receptor and is directly affected by this receptor; the downstream genes of PLC and PRKCB can combine with nerve calcium-regulating protein inhibitors, leading to renal insufficiency.…”

“…When miR‐200b was used to interfere with gene expression in sheep hypothalamic neurons, GnAQ gene expression was downregulated, PRKCB and GnA11 gene expression levels were upregulated, and kisspeptin/GPR54 signaling system‐related gene expression in the photoperiodic regulatory pathway was upregulated. Thus, the expression of GnRH was upregulated . In this study, sheep hypothalamic neurons were subjected to different concentrations of folate, and DNA methylation levels in the GnAQ promoter region were detected by BSP.…”

“…Thus, the expression of GnRH was upregulated. 12 In this study, sheep hypothalamic neurons were subjected to different concentrations of folate, and DNA methylation levels in the GnAQ promoter region were detected by BSP. Appropriate folate concentrations promoted GnAQ promoter region methylation.…”

“…The regulation of the estrous pathway from the nutrients folate and tyrosine has been summarized (Figure 1) 10 ; the hypothalamic secretion of GnRH is regulated by multiple signals, and GnAQ is used as a signal switch for cell signaling. 11 Bioinformatics analysis predictions that miR-200b is a target for the negative regulation of GnAQ have been validated, 12 and the upregulation of the expression profiles of a series of genes in the GnRH signaling pathway, through feedback regulation of GPR54/ KISS1 and GnRH, affects the estrous process. GnAQ is expressed at high levels in the hypothalamus of Kazakh sheep; the activity of the Hypothalamo pituitary gonadal (HPG) axis is regulated by the photoperiod, and nutrition may be a key factor affecting GnAQ expression.…”