Hypusination of eukaryotic initiation factor 5A via cAMP-PKA-ERK1/2 pathway is required for ligand-induced downregulation of LH receptor mRNA expression in the ovary

Polyamines in Ovarian Aging and Disease

Ovarian aging and disease-related decline in fertility are challenging medical and economic issues with an increasing prevalence. Polyamines are a class of polycationic alkylamines widely distributed in mammals. They are small molecules essential for cell growth and development. Polyamines alleviate ovarian aging through various biological processes, including reproductive hormone synthesis, cell metabolism, programmed cell death, etc. However, an abnormal increase in polyamine levels can lead to ovarian damage and promote the development of ovarian disease. Therefore, polyamines have long been considered potential therapeutic targets for aging and disease, but their regulatory roles in the ovary deserve further investigation. This review discusses the mechanisms by which polyamines ameliorate human ovarian aging and disease through different biological processes, such as autophagy and oxidative stress, to develop safe and effective polyamine targeted therapy strategies for ovarian aging and the diseases.

Identification of differentially expressed genes associated with precocious puberty by suppression subtractive hybridization in goat pituitary tissues

The aim of this study was to identify genes related to precocious puberty expressed in the pituitary of goats at different growth stages by suppression subtractive hybridization (SSH). The pituitary glands from Jining Gray (JG) goats (early puberty) and Liaoning Cashmere (LC) goats (late puberty) at 30, 90, and 180 days were used in this study. To identify differentially expressed genes (DEGs) in the pituitary glands, mRNA was extracted from these tissues, and SSH libraries were constructed and divided into the following groups: juvenile group (30-JG vs. 30-LC, API), puberty group (90-JG vs. 180-LC, BPI), and control group (90-JG vs. 90-LC, EPI). A total of 60, 49, and 58 DEGs were annotated by 222 Gene Ontology (GO) terms and 75 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Most of the DEGs were significantly enriched in GO terms related to 'structural constituent of ribosome', 'translation' and 'GTP binding', and numerous DEGs were also significantly enriched in KEGG terms related to the Jak-STAT signaling and oocyte meiosis pathways. Candidate genes associated with precocious puberty and sexual development were screened from the SSH libraries. These genes were analyzed to determine if they were expressed in the pituitary tissues of the goats at different growth stages and to identify genes that may influence the hypothalamic-pituitary-gonadal (HPG) axis. In this study, we found precocious puberty-related genes (such as PRLP0, EIF5A, and YWHAH) that may be interesting from an evolutionary perspective and that could be investigated for use in future goat breeding programs. Our results provide a valuable dataset that will facilitate further research into the reproductive biology of goats.

Identification of mRNAs and lncRNAs Involved in the Regulation of Follicle Development in Goat

Follicular development and maturation has a significant impact on goat reproductive performance, and it is therefore important to understand the molecular basis of this process. The importance of long non-coding RNAs (lncRNAs) in mammalian reproduction has been established, but little is known about the roles of lncRNAs in different follicular stages, especially in goats. In this study, RNA sequencing (RNA-seq) of large follicles (>10 mm) and small follicles (<3 mm) of Chuanzhong black goats was performed to investigate the regulatory mechanisms of lncRNAs and mRNAs in follicular development and maturation. A total of 8 differentially expressed lncRNAs (DElncRNAs) and 1,799 DEmRNAs were identified, and the majority of these were upregulated in small follicles. MRO, TC2N, CDO1, and NTRK1 were potentially associated with follicular maturation. KEGG pathway analysis showed that the DEmRNAs involved in ovarian steroidogenesis (BMP6, CYP11A1, CYP19A1, 3BHSD, STAR, LHCGR, and CYP51A1) and cAMP signaling play roles in regulating follicular maturation and developmental inhibition respectively. Five target pairs of DElncRNA-DEmRNA, namely, ENSCHIT00000001255-OTX2, ENSCHIT00000006005-PEG3, ENSCHIT00000009455-PIWIL3, ENSCHIT00000007977-POMP, and ENSCHIT00000000834-ACTR3 in co-expression analysis provide a clue in follicular development and maturation of lncRNA-mRNA interaction. Our findings provide a valuable resource for lncRNA studies, and could potentially provide a deeper understanding of the genetic basis and molecular mechanisms of goat follicular development and maturation.

Knockdown of LGALS12 inhibits porcine adipocyte adipogenesis via PKA-Erk1/2 signaling pathway

Increasing intramuscular (IM) fat while concomitantly decreasing subcutaneous (SC) fat content is one major goal of pig breeding. Identifying genes involved in lipid metabolism is critical for this goal. Galectin-12 (LGALS12) has been proven to be an important regulator of fat deposition in mouse models; however, the effect and regulatory mechanisms of LGALS12 on porcine adipogenesis are still unknown. In this study, the effects of LGALS12 on fat deposition were explored with primary culture of porcine SC and IM adipocytes. Analysis of LGALS12 expression across different tissues revealed that LGALS12 was predominantly expressed in adipose tissue. The LGALS12 expression patterns across stages of adipocyte differentiation were also evaluated, with differences observed between SC and IM fat. Small interfering RNA (siRNA) of LGALS12 was designed and transfected into porcine adipocytes derived from SC and IM fat. After transfection, the expression level of LGALS12 was significantly reduced, and the number of lipid droplets was reduced in adipocytes from both SC and IM fat. Simultaneously, the levels of adipogenic markers, including PPARγ and aP2, were decreased, whereas hydrolysis markers, including adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), were increased. Furthermore, the activation of lipolysis signals, such as the phosphorylation of PKA and Erk1/2, were observed with LGALS12 knockdown in terminally differentiated adipocytes from both SC and IM sources. Taken together, these results suggest that LGALS12 knockdown can inhibit adipogenesis of porcine adipocytes by downregulating lipogenic genes and activating the PKA-Erk1/2 signaling pathway.

Regulation of gene expression by translation factor eIF5A: Hypusine-modified eIF5A enhances nonsense-mediated mRNA decay in human cells

Nonsense-mediated mRNA decay (NMD) couples protein synthesis to mRNA turnover. It eliminates defective transcripts and controls the abundance of certain normal mRNAs. Our study establishes a connection between NMD and the translation factor eIF5A (eukaryotic initiation factor 5A) in human cells. eIF5A modulates the synthesis of groups of proteins (the eIF5A regulon), and undergoes a distinctive two-step post-translational modification (hypusination) catalyzed by deoxyhypusine synthase and deoxyhypusine hydroxylase. We show that expression of NMD-susceptible constructs was increased by depletion of the major eIF5A isoform, eIF5A1. NMD was also attenuated when hypusination was inhibited by RNA interference with either of the two eIF5A modifying enzymes, or by treatment with the drugs ciclopirox or deferiprone which inhibit deoxyhypusine hydroxylase. Transcriptome analysis by RNA-Seq identified human genes whose expression is coordinately regulated by eIF5A1, its modifying enzymes, and the pivotal NMD factor, Upf1. Transcripts encoding components of the translation system were highly represented, including some encoding ribosomal proteins controlled by alternative splicing coupled to NMD (AS-NMD). Our findings extend and strengthen the association of eIF5A with NMD, previously inferred in yeast, and show that hypusination is important for this function of human eIF5A. In addition, they advance drug-mediated NMD suppression as a therapeutic opportunity for nonsense-associated diseases. We propose that regulation of mRNA stability contributes to eIF5A's role in selective gene expression.

LHCGR Expression During Follicle Stimulating Hormone-Induced Follicle Growth Is Negatively Regulated by Eukaryotic Initiation Factor 5A

We have shown that the transient changes in the expression of luteinizing hormone/choriogonadotropin receptor (LHCGR) messenger RNA (mRNA) during the ovarian cycle occurs, at least in part, through a posttranscriptional mechanism involving an LHCGR mRNA-binding protein (LRBP). Eukaryotic initiation factor 5A (eIF5A), an LRBP-interacting protein, participates in this process. eIF5A undergoes hypusination, a unique posttranslational modification that is necessary for its functions. This study examined the role of eIF5A in follicle-stimulating hormone (FSH)-induced LHCGR expression during follicular growth. Treatment of primary cultures of rat granulosa cells with FSH and 17β-estradiol (E2) showed a time-dependent increase in LHCGR mRNA expression. Conversely, inhibition of endogenous hypusination of eIF5A using N1-guanyl-1,7-diaminoheptane (GC7), a hypusination inhibitor, showed a greater increase in LHCGR mRNA expression over that produced by FSH and E2 alone. Further studies were carried out to determine the mechanism by which inhibition of hypusination of eIF5A causes an increase in LHCGR mRNA expression. Because LHCGR expression is negatively regulated by LRBP, the effect of inhibiting hypusination of eIF5A on LRBP expression was examined. The results showed a decrease in the expression of LRBP mRNA and protein when hypusination of eIF5A was inhibited by GC7. Because LRBP promotes LHCGR mRNA degradation, the results of this study support the notion that by inhibiting eIF5A hypusination, FSH reduces the expression of LRBP. This increases LHCGR mRNA expression by abrogating the inhibitory action of LRBP.