Effects of lanosterol on in vitro maturation of porcine oocytes

Strategies of targeting CYP51 for IFIs therapy: Emerging prospects, opportunities and challenges

CYP51, a monooxygenase associated with the sterol synthesis pathway, is responsible for the catalysis of the 14-methyl hydroxylation reaction of lanosterol precursors. This enzyme is widely present in microorganisms, plants, and mammals. In mammals, CYP51 plays a role in cholesterol production, oligodendrocyte formation, oocyte maturation, and spermatogenesis. In fungal cells, CYP51 is an enzyme that synthesizes membrane sterols. By inhibiting fungal CYP51, ergosterol synthesis can be inhibited and ergosterol membrane fluidity is altered, resulting in fungal cell apoptosis. Thus, targeting CYP51 is a reliable antifungal strategy with important implications for the treatment of invasive fungal infections (IFIs). Many CYP51 inhibitors have been approved by the FDA for clinical treatment. However, several limitations of CYP51 inhibitors remain to be resolved, including fungal resistance, hepatotoxicity, and drug-drug interactions. New broad-spectrum, anti-resistant, highly selective CYP51 inhibitors are expected to be developed to enhance clinical efficacy and minimize adverse effects. Herein, we summarize the structural features and biological functions of CYP51 and emphatically analyze the structure-activity relationship (SAR) and therapeutic potential of different chemical types of small-molecule CYP51 inhibitors. We also discuss the latest progress of novel strategies, providing insights into new drugs targeting CYP51 for clinical practice.

Dietary flaxseed oil and vitamin E improve semen quality via propionic acid metabolism

Introduction

Flaxseed oil (FO) and vitamin E (VE) both have antioxidant effects on sperm. The present study investigated the effects of dietary supplementation with FO and/or VE on semen quality.

Methods

16 fertile Simmental bulls were selected and randomly divided into 4 groups (n = 4): the control group (control diet), FO group (control diet containing 24 g/kg FO), VE group (control diet containing 150 mg/kg VE) and FOVE group (control diet containing 150 mg/kg VE and 24 g/kg FO), and the trial lasted 10 weeks.

Results

The results showed that the addition of FO independently can increase sperm motion parameters, the levels of catalase (CAT), glutathione peroxidase (GSH-Px), testosterone (T) and estradiol (E2), while reduce oxidative stress in seminal plasma (P < 0.05). Supplement of VE independently can increased the motility, motility parameters, CAT and superoxide dismutase (SOD) levels, and reduce oxidative stress in seminal plasma (P < 0.05). There was an interaction effect of FO × VE on motility and reactive oxygen species (ROS), while GSH-Px and ROS were affected by week × VE 2-way interaction, levels of T and E2 were also affected by the dietary FO × week interaction (P < 0.05). The triple interaction effects of FO, VE and week were significant for malondialdehyde (MDA) (P < 0.05). Compared with the control group, sperm from the FOVE group had a significantly higher in vitro fertilization (IVF) rate, and subsequent embryos had increased developmental ability with reduced ROS levels at the eight-cell stage, then increased adenosine triphosphate (ATP) content and gene expression levels of CAT, CDX2, Nanog, and SOD at the blastocyst stage (P < 0.05). Metabolomic and transcriptomic results indicated that dietary supplementation of FO and VE increased the expression of the metabolite aconitic acid, as well as the expression of ABAT and AHDHA genes.

Conclusion

With in-silico analysis, it can be concluded that the effects of dietary FO and VE on improving semen quality and embryo development may be related to increased aconitic acid via the ABAT and AHDHA genes involved in the propionic acid metabolism pathway.

Investigating the toxically homogenous effects of three lanthanides on zebrafish

The adverse effects of rare earth elements (REEs) have been increasingly reported in the past decades and have raised concern about their environmental toxicities. However, the available data is insufficient to elucidate the toxic effects, mechanisms, and whether the toxicity across all REEs is uniform. In this study, zebrafish were exposed to 0, 0.8, 1.6, 3.2, 6.4, 12.8 and 25.6 mg/L Ln(NO₃)₃•6H₂O to test the acute toxicity of La(III), Ce(III), and Nd(III). LC₅₀ of the three lanthanides was compared to the extent of the impact on gene expression. We carried out the functionally grouped network-based transcriptome analysis using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to explore the molecular mechanisms. The acute toxicity test showed that LC₅₀ of La(III), Ce(III), and Nd(III) were 2.53, 2.03, and 2.76 mg/L, respectively. Consistent with acute toxicity, Ce(III) caused a little more DEGs than La(III) and Nd(III). Some biological processes such as metabolism of xenobiotics, oocyte meiosis, steroid biosynthesis, DNA replication, and p53 signaling pathway were affected following exposure of all the three lanthanides. Ce(III) also induced changes in the chemokine-mediated signaling pathway. The results indicated that the lethality is comparable, and the toxic patterns are similar across the three lanthanides. This study gives comparative research on the toxicities of three lanthanides to model organism zebrafish.

Role of cholesterol metabolism in the anticancer pharmacology of selective estrogen receptor modulators

Selective estrogen receptor modulators (SERMs) are a class of compounds that bind to estrogen receptors (ERs) and possess estrogen agonist or antagonist actions in different tissues. As such, they are widely used drugs. For instance, tamoxifen, the most prescribed SERM, is used to treat ERα-positive breast cancer. Aside from their therapeutic targets, SERMs have the capacity to broadly affect cellular cholesterol metabolism and handling, mainly through ER-independent mechanisms. Cholesterol metabolism reprogramming is crucial to meet the needs of cancer cells, and different key processes involved in cholesterol homeostasis have been associated with cancer progression. Therefore, the effects of SERMs on cholesterol homeostasis may be relevant to carcinogenesis, either by contributing to the anticancer efficacy of these compounds or, conversely, by promoting resistance to treatment. Understanding these aspects of SERMs actions could help to design more efficacious therapies. Herein we review the effects of SERMs on cellular cholesterol metabolism and handling and discuss their potential in anticancer pharmacology.

Lanosterol influences cytoplasmic maturation of pig oocytes in vitro and improves preimplantation development of cloned embryos

Lanosterol is a precursor of meiosis-activating sterols in the cholesterol biosynthetic pathway and induces a physiological signal that instructs the oocyte to reinitiate meiosis. In this study, we examined the effect of lanosterol on IVM of porcine oocytes, specifically on nuclear maturation, cytoplasmic maturation by investigating intracellular glutathione (GSH) levels and lipid content, embryonic development after parthenogenetic activation and somatic cell nuclear transfer (SCNT), and on gene expression in cumulus cells, oocytes, and SCNT-derived blastocysts. There was no significant difference in nuclear maturation rates between the control and treatment groups (10, 50, and 100 μM of lanosterol added to IVM culture medium). Supplementation with 50-μM lanosterol significantly increased lipid content and GSH levels and decreased reactive oxygen species levels compared with the control. In addition, oocytes treated with 50 μM of lanosterol exhibited significantly increased blastocyst formation rates and total cell numbers after parthenogenetic activation (30.3% and 63.9 vs. 21.6% and 36.5, respectively) and SCNT (18.2% and 53.7 vs. 12.6% and 37.5, respectively), when compared with the control group. Cumulus cells treated with 50 μM of lanosterol showed significantly increased 14α-demethylase, Δ14-reductase, and Δ7-reductase mRNA transcript levels. Significantly increased PPARγ, SREBF1, GPX1, and Bcl-2 and decreased Bax transcript levels were observed in mature oocytes treated with 50 μM of lanosterol compared with the control. SCNT blastocysts derived from 50-μM lanosterol-treated oocytes had significantly higher POU5F1, FGFR2, and Bcl-2 transcript levels than control SCNT-derived blastocysts. In conclusion, supplementation with 50 μM of lanosterol during IVM improves preimplantation development of SCNT embryos by elevating lipid content of oocytes, increasing GSH levels, decreasing reactive oxygen species levels, and regulating genes related to the cholesterol biosynthetic pathway in cumulus cells, to lipid metabolism and apoptosis in oocytes, and their developmental potential and apoptosis in blastocysts.

Toxicity evaluation of ethanol treatment during in vitro maturation of porcine oocytes and subsequent embryonic development following parthenogenetic activation and in vitro fertilization

Ethanol is frequently used as a solvent in several techniques for in vitro production (IVP). It is also used for the parthenogenetic activation (PA) of oocytes. Although a number of studies have suggested that ethanol has detrimental effects on fibroblasts and neuronal cells, little attention has been paid to the effects of ethanol on porcine oocytes. Thus, the aim of this study was to evaluate the effects of the addition of ethanol to in vitro maturation (IVM) medium. We investigated the effects of ethanol (0, 1 and 3%) on the following parameters: nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, and subsequent embryonic development following PA and in vitro fertilization (IVF). After 44 h of IVM, the 3% group showed a significant (P<0.05) decrease in nuclear maturation (34.0%) compared with the control group (70.3%). The 1 and 3% groups exhibited a significant (P<0.05) decrease in GSH levels and an increase in ROS levels compared with the control group. Compared with the control group, the 3% group had significantly (P<0.05) lower cleavage rates following PA (51.6 vs. 86.9%) and IVF (53.2 vs. 70.6%), as well as lower blastocyst formation rates and decreased total cell numbers following PA (11.3% and 31.8 vs. 53.6% and 65.4, respectively) and IVF (4.1% and 22.0 vs. 36.1% and 70.3, respectively). We evaluated the mRNA expression levels of DNA repair‑related and apoptosis‑related genes in the cumulus oocyte complexes (COCs). The 1% ethanol group showed significantly (P<0.05) higher mRNA expression levels of poly(ADP‑ribose) polymerase‑1 (PARP‑1), Bax, Bak and caspase‑3, and the 3% ethanol group had significantly (P<0.05) increased PARP‑1, Bax and caspase‑3 mRNA expression levels compared with the control group. Our results suggest that treatment with >1% ethanol during IVM exerts a toxic effect on the developmental potential of PA and IVF porcine embryos by decreasing the intracellular GSH level, thereby increasing the intracellular ROS level and upregulating the expression of apoptosis‑related genes.

Gene expression differences induced by equimolar low doses of LH or hCG in combination with FSH in cultured mouse antral follicles

In a natural cycle, follicle growth is coordinated by FSH and LH. Follicle growth stimulation in Assisted Reproductive Technologies (ART) requires antral follicles to be exposed to both FSH and LH bioactivity, especially after GNRH analog pretreatment. The main aim was to detect possible differences in gene expression in granulosa cells after exposing the follicle during antral growth to LH or hCG, as LH and hCG are different molecules acting on the same receptor. Effects of five gonadotropin treatments were investigated for 16 genes using a mouse follicle culture model. Early (day 6) antral follicles were exposed to high recombinant FSH combined or not with equimolar concentrations of recombinant LH (rLH) or recombinant hCG (rhCG) and to highly purified human menopausal gonadotropin (HP-hMG) for 6 h, 12 h, or 3 days. Expression differences were tested for genes involved in steroidogenesis: Mvk, Lss, Cyp11a1, Hsd3b1, Cyp19a1, Nr4a1, and Timp1; final granulosa differentiation: Lhcgr, Oxtr, Pgr, Egfr, Hif1a, and Vegfa; and cytokines: Cxcl12, Cxcr4, and Sdc4. Lhcgr was present and upregulated by gonadotropins. Nr4a1, Cxcl12, and Cxcr4 showed a different expression pattern if LH bioactivity was added to high FSH in the first hours after exposure. However, no signs of premature luteinization were present even after a 3-day treatment as shown by Cyp19a1, Oxtr, Pgr, and Egfr and by estrogen and progesterone measurements. The downstream signaling by rhCG or rLH through the LHCGR was not different for this gene selection. Granulosa cells from follicles exposed to HP-hMG showed an enhanced expression level for several genes compared with recombinant gonadotropin exposure, possibly pointing to enhanced cellular activity.

Effect of lanosterol on the in vitro maturation in semi-defined culture system of prepubertal ewe oocytes

The choice of medium and supplements can affect meiotic regulation and may have an impact on the regulation of mammalian oocyte growth and embryonic cell function. The aim of the present study was to assess the effects of oxygen concentration and endogenous lanosterol on the in vitro maturation (IVM) media without serum and based on recombinant human chorionic gonadotrophin in prepubertal ewe oocytes. Firstly, the effect of varying oxygen concentrations (5% and 20%) during IVM in TCM-199 supplemented (4 mg/ml bovine serum albumin (BSA), 100 μM cysteamine, 0.3 mM sodium pyruvate, 0.1 UI/ml recombinant follicle-stimulating hormone (r-FSH; Gonal-F® 75 UI, Serono, Italy), 0.1 UI/ml recombinant leuteinizing hormone (r-LH; Lhadi® 75 UI, Serono, Italy) and 1 μg/ml estradiol-17β) on subsequent nuclear maturation of oocytes examined under ultraviolet light following staining with bisbenzimide (Hoechst 33342) was investigated. Secondly, two concentrations of lanosterol (0, 10 and 50 μM) were added to the IVM medium. Nuclear maturation of oocytes was examined as previously. Lipid content in oocytes, an important indicator of cytoplasmic maturity, was also measured using Nile red fluorescent stain. The results showed that low oxygen concentration affected the nuclear maturation. Similarly, a significantly higher rate of meiosis resumption was observed with 10 μM (72.3%) of lanosterol compared with the control (51.8%) or 50 μM of lanosterol (59.4%). A significantly higher content of lipids was also observed with 10 and 50 μM of lanosterol (7.3 ± 0.2 × 106 and 7.4 ± 0.2 × 106 arbitrary units of fluorescence) compared with the control (6.7 ± 0.2 × 106 arbitrary units of fluorescence). The results indicate that 10 μM lanosterol during IVM in medium without serum and based on recombinant human chorionic gonadotrophin has a positive effect on maturation of prepubertal ewe oocytes.