A Novel Gonadotropin-Releasing Hormone 1 (Gnrh1) Enhancer-Derived Noncoding RNA Regulates Gnrh1 Gene Expression in GnRH Neuronal Cell Models

Age-related changes in gonadotropin-releasing hormone (GnRH) splice variants in mouse brain

Gonadotropin-releasing hormone (GnRH) is the primary regulator of the mammalian reproductive axis. We investigated the spatiotemporal expression of GnRH splice variants (V1, V2, and V3) and splicing factors (Srsf7, Srsf9, and Tra-2) in the male mice brain. Further, using in silico tools, we predicted protein structure and the reason for the low translational efficiency of V2 and V3. Messenger RNA levels of GnRH variants and splicing factors were quantified using real-time reverse transcription-polymerase chain reaction at different age groups. Our data show that expression of almost all the variants alters with aging in all the brain regions studied; even in comparison to the hypothalamus, several brain areas were found to have higher expression of these variants. Hypothalamic expression of splicing factors such as Srsf7, Srsf9, and Tra-2 also change with aging. Computational studies have translation repressors site on the V3, which probably reduces its translation efficiency. Also, V2 is an intrinsically disordered protein that might have a regulatory or signaling function. In conclusion, this study provides novel crucial information and multiple starting points for future analysis of GnRH splice variants in the brain.

Transcriptomic Changes of Photoperiodic Response in the Hypothalamus Were Identified in Ovariectomized and Estradiol-Treated Sheep

Accurate timing of seasonal changes is an essential ability for an animal’s survival, and the change in the photoperiod is the key factor affecting reproductive seasonality in mammals. Emerging evidence has suggested that multiple hypothalamic genes participate in the photoperiod-induced regulation of reproductive activities in sheep, but the mechanism is still unclear. In this study, we initially examined the plasma level of two major reproductive hormones, namely, follicle-stimulating hormone (FSH) and prolactin (PRL), under different photoperiods in ovariectomized and estradiol-treated (OVX + E2) sheep using radioimmunoassay (RIA). Of the two hormones, the concentration of PRL significantly increased with the extension of the photoperiod, while FSH showed the opposite trend. Subsequently, an examination of the transcriptomic variation between the short photoperiod (SP) and long photoperiod (LP) was conducted. Differential expression analyses and functional annotation showed that several key genes in the insulin secretion (VAMP2, PRKACB, PRKCG, and PLCB1), GnRH (MAPK13, CGA, CDC42, ATF4, and LHB) pathways, and circadian entrainment (KCNJ5, PER1, GNB2, MTNR1A, and RASD1), as well as numerous lncRNAs, including XR_173257.3, XR_173415.3, XR_001435315.1, XR_001024596.2, and XR_001023464.2, were shown potentially vital for the hypothalamic photoperiodic response. Four of the differentially expressed mRNAs and lncRNAs were validated by qPCR. The constructed mRNA–mRNA interaction networks further revealed that transcripts potentially participated in hypothalamic thyroid hormone synthesis, endocrine resistance, and neuroactive ligand–receptor interactions. The interactome analysis of lncRNAs and their targets implied that XR_173257.3 and its target arylalkylamine N-acetyltransferase (AANAT) and XR_173415.3 and its target TH might participate in the regulation of seasonal reproduction. Together, the changes in reproductive hormones and transcriptome will help to determine the important photoperiod-induced lncRNAs and mRNAs and provide a valuable resource for further research on reproductive seasonality in sheep.

Transcriptome Analysis Reveals Differentially Expressed Genes and Long Non-coding RNAs Associated With Fecundity in Sheep Hypothalamus With Different FecB Genotypes

Small-tailed Han sheep, with different FecB genotypes, manifest distinct ovulation rates and fecundities, which are due to differences in reproductive hormones secreted by the hypothalamic-pituitary-ovarian axis. Nevertheless, the function of the hypothalamus against a FecB mutant background on increasing ovulation rate is rarely reported. Therefore, we determined the expression profiles of hypothalamus tissue collected from six wild-type (WW) and six FecB mutant homozygous (BB) ewes at the follicular and luteal phases by whole-transcriptome sequencing. We identified 53 differentially expressed mRNAs (DEGs) and 40 differentially expressed long non-coding RNAs (DELs) between the two estrus states. Functional annotation analysis revealed that one of the DEGs, PRL, was particularly enriched in the hypothalamic function, hormone-related, and reproductive pathways. The lncRNA-target gene interaction networks and KEGG analysis in combination suggest that the lncRNAs LINC-676 and WNT3-AS cis-acting on DRD2 and WNT9B in different phases may induce gonadotropin-releasing hormone (GnRH) secretion. Furthermore, there were differences of regulatory elements and WNT gene family members involved in the follicular-luteal transition in the reproductive process between wild-type (WNT7A) and FecB mutant sheep (WNT9B). We combined the DEG and DEL data sets screened from different estrus states and genotypes. The overlap of these two sets was identified to select the mRNAs and lncRNAs that have major effects on ovulation. Among the overlapping molecules, seven DEGs and four DELs were involved in the follicular-luteal transition regulated by FecB mutation. Functional annotation analysis showed that two DEGs (FKBP5 and KITLG) were enriched in melanogenesis, oxytocin, and GnRH secretion. LINC-219386 and IGF2-AS were highly expressed in the BB ewes compared with WW ewes, modulating their target genes (DMXL2 and IGF2) to produce more GnRH during follicular development, which explains why mutated ewes produced more mature follicles. These results from expression profiling of the hypothalamus with the FecB mutation at different estrus states provide new insights into how the hypothalamus regulates ovulation under the effect of the FecB mutation.

Oncogenic seRNA functional activation: a novel mechanism of tumorigenesis

seRNA is a noncoding RNA (ncRNA) transcribed from active super-enhancer (SE), through which SE exerts biological functions and participates in various physiological and pathological processes. seRNA recruits cofactor, RNA polymerase II and mediator to constitute and stabilize chromatin loop SE and promoter region, which regulates target genes transcription. In tumorigenesis, DNA insertion, deletion, translocation, focal amplification and carcinogen factor mediate oncogenic SE generation, meanwhile, oncogenic SE transcribes into tumor-related seRNA, termed as oncogenic seRNA. Oncogenic seRNA participates in tumorigenesis through activating various signal-pathways. The recent reports showed that oncogenic seRNA implicates in a widespread range of cytopathological processes in cancer progression including cell proliferation, apoptosis, autophagy, epithelial-mesenchymal transition, extracellular matrix stiffness and angiogenesis. In this article, we comprehensively summarized seRNA’s characteristics and functions, and emphatically introduced inducible formation of oncogenic seRNA and its functional mechanisms. Lastly, some research strategies on oncogenic seRNA were introduced, and the perspectives on cancer therapy that targets oncogenic seRNA were also discussed.

RNA-seq analysis of lncRNA-controlled developmental gene expression during puberty in goat & rat

Background

Puberty is a pivotal stage in female animal development, and marks the onset of reproductive capability. However, little is known about the function of lncRNAs (long noncoding RNAs) in puberty. Therefore, RNA-seq analysis were performed between goats and rats to clarify the roles of lncRNAs and mRNAs in the onset of puberty.

Results

In the present study, the length of lncRNAs, the length of the open reading frame and the exon count were compared between the two species. Furthermore, functional annotation analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis of lncRNAs target genes and differentially expressed mRNA demonstrated the significantly enriched terms, such as AMPK signaling pathway, oxytocin signaling pathway, insulin secretion as well as pheromone receptor activity, and some other signaling pathways which were involved in the regulation of female puberty. Moreover, our results of siRNA interference in vitro showed the candidate lncRNA XLOC_446331 may play a crucial role in regulating female puberty.

Conclusion

In conclusion, the RNA-seq analysis between goat and rat provide novel candidate regulators for genetic and molecular studies on female puberty.

Electronic supplementary material

The online version of this article (10.1186/s12863-018-0608-9) contains supplementary material, which is available to authorized users.

Transcriptional interaction between cFOS and the homeodomain-binding transcription factor VAX1 on the GnRH promoter controls Gnrh1 expression levels in a GnRH neuron maturation specific manner

Gonadotropin-releasing hormone (GnRH) is required for pubertal onset and reproduction, thus the control of GnRH transcription is tightly regulated during development and adulthood. GnRH neuron development depends on transcription factors of the homeodomain family. For example, Ventral anterior homeobox 1 (Vax1) is necessary to maintain GnRH expression after embryonic day 13 in the mouse. To further our understanding of the mechanisms by which VAX1 regulates GnRH gene expression, we asked whether VAX1 interacts with other transcription factors to modify GnRH expression levels. Using the GnRH cell lines, GN11 and GT1-7, we found that activation of PKC enhances expression of the immediate early gene cFos in both GN11, and GT1-7, and represses expression of Vax1 in GT1-7. Further, VAX1 interacts with cFOS while bound to the GnRH promoter. In immature GN11 cells, VAX1 and cFOS enhance GnRH expression, whereas VAX1 and cFOS have a repressive role in the mature GT1-7 cells.

A Long Noncoding RNA, lncRNA-Amhr2, Plays a Role in Amhr2 Gene Activation in Mouse Ovarian Granulosa Cells

Anti-Müllerian hormone (AMH) is critical to the regression of Müllerian ducts during mammalian male differentiation and targets ovarian granulosa cells and testicular Sertoli and Leydig cells of adults. Specific effects of AMH are exerted via its receptor, AMH type II receptor (Amhr2), but the mechanism by which the Amhr2 gene is specifically activated is not fully understood. To see whether a proximal promoter was sufficient for Amhr2 gene activation, we generated transgenic mice that bore the enhanced green fluorescent protein (EGFP) gene driven by a 500-bp mouse Amhr2 gene promoter. None of the established 10 lines, however, showed appropriate EGFP expression, indicating that the 500-bp promoter was insufficient for Amhr2 gene activation. As a regulatory element, we found a long noncoding RNA, lncRNA-Amhr2, transcribed from upstream of the Amhr2 gene in ovarian granulosa cells and testicular Sertoli cells. In primary granulosa cells, knockdown of lncRNA-Amhr2 resulted in a decrease of Amhr2 messnger RNA level, and a transient reporter gene assay showed that lncRNA-Amhr2 activation increased Amhr2 promoter activity. The activity was correlated with lncRNA-Amhr2 transcription in stably transfected OV3121 cells derived from mouse granulosa cells. Moreover, by the Tet-on system, the induction of lncRNA-Amhr2 transcription dramatically increased Amhr2 promoter activity in OV3121 cells. These results indicate that lncRNA-Amhr2 plays a role in Amhr2 gene activation in ovarian granulosa cells by enhancing promoter activity, providing insight into Amhr2 gene regulation underlying the AMH signaling in the female reproductive system.