SRXN1 Is Necessary for Resolution of GnRH-Induced Oxidative Stress and Induction of Gonadotropin Gene Expression

Combining genome-wide association study and transcriptome analysis to identify molecular markers and genetic basis of population-asynchronous ovarian development in Coilia nasus

Coilia nasus, a migratory fish species found in the middle and lower reaches of the Yangtze River and along offshore areas of China, possesses considerable aquacultural and economic potential. However, the species faces challenges due to significant variation in the gonadal development rate among females, resulting in inconsistent ovarian maturation times at the population level, an extended reproductive period, and limitations on fish growth rate due to ovarian prematurity. In the present study, we combined genome-wide association study (GWAS) and comparative transcriptome analysis to investigate the potential single nucleotide polymorphisms (SNPs) and candidate genes associated with population-asynchronous ovarian development in C. nasus. Genotyping of the female population based on whole-genome resequencing yielded 2 120 695 high-quality SNPs, 39 of which were suggestively associated with ovarian development. Of note, a significant SNP peak on LG21 containing 30 suggestively associated SNPs was identified, with cpne5a determined as the causal gene of the peak. Therefore, single-marker and haplotype association analyses were performed on cpne5a, revealing four genetic markers ( P<0.05) and seven haplotypes (r 2>0.9) significantly associated with the phenotype. Comparative transcriptome analysis of precociously and normally maturing individuals screened out 29 and 426 overlapping differentially expressed genes in the brain and ovary, respectively, between individuals of different body sizes. Integrating the GWAS and transcriptome analysis results, this study identified genes and pathways related to hypothalamic-pituitary-gonadal axis hormone secretion, extracellular matrix, angiogenesis, and gap junctions involved in population-asynchronous ovarian development. The insights gained from this study provide a basis for a deeper understanding of the molecular mechanisms underlying ovarian development in fish and may facilitate the genetic breeding of C. nasus strains exhibiting population-synchronous ovarian development in the future.

Lipopolysaccharide-induced chronic inflammation increases female serum gonadotropins and shifts the pituitary transcriptomic landscape

Introduction

Female reproductive function depends on a choreographed sequence of hormonal secretion and action, where specific stresses such as inflammation exert profound disruptions. Specifically, acute LPS-induced inflammation inhibits gonadotropin production and secretion from the pituitary, thereby impacting the downstream production of sex hormones. These outcomes have only been observed in acute inflammatory stress and little is known about the mechanisms by which chronic inflammation affects reproduction. In this study we seek to understand the chronic effects of LPS on pituitary function and consequent luteinizing and follicle stimulating hormone secretion.

Methods

A chronic inflammatory state was induced in female mice by twice weekly injections with LPS over 6 weeks. Serum gonadotropins were measured and bulk RNAseq was performed on the pituitaries from these mice, along with basic measurements of reproductive biology.

Results

Surprisingly, serum luteinizing and follicle stimulating hormone was not inhibited and instead we found it was increased with repeated LPS treatments.

Discussion

Analysis of bulk RNA-sequencing of murine pituitary revealed paracrine activation of TGFβ pathways as a potential mechanism regulating FSH secretion in response to chronic LPS. These results provide a framework with which to begin dissecting the impacts of chronic inflammation on reproductive physiology.

Nomilin and its analogue obacunone alleviate NASH and hepatic fibrosis in mice via enhancing antioxidant and anti-inflammation capacity

Nonalcoholic steatohepatitis (NASH) and hepatic fibrosis are leading causes of cirrhosis with rising morbidity and mortality worldwide. Currently, there is no appropriate treatment for NASH and hepatic fibrosis. Many studies have shown that oxidative stress is a main factor inducing NASH. Nomilin (NML) and obacunone (OBA) are limonoid compounds naturally occurring in citrus fruits with various biological properties. However, whether OBA and NML have beneficial effects on NASH remains unclear. Here, we demonstrated that OBA and NML inhibited hepatic tissue necrosis, inflammatory infiltration and liver fibrosis progression in methionine and choline-deficient (MCD) diet, carbon tetrachloride (CCl4 )-treated and bile duct ligation (BDL) NASH and hepatic fibrosis mouse models. Mechanistic studies showed that NML and OBA enhanced anti-oxidative effects, including reduction of malondialdehyde (MDA) level, increase of catalase (CAT) activity and the gene expression of glutathione S-transferases (GSTs) and Nrf2-keap1 signaling. Additional, NML and OBA inhibited the expression of inflammatory gene interleukin 6 (Il-6), and regulated the bile acid metabolism genes Cyp3a11, Cyp7a1, multidrug resistance-associated protein 3 (Mrp3). Overall, these findings indicate that NML and OBA may alleviate NASH and liver fibrosis in mice via enhancing antioxidant and anti-inflammation capacity. Our study proposed that NML and OBA may be potential strategies for NASH treatment.

Gastrointestinal Degradation and Toxicity of Disinfection Byproducts in Drinking Water Using In Vitro Models and the Roles of Gut Microbiota

Disinfection byproducts (DBPs) in drinking water are mainly exposed to the human body after oral ingestion and degradation in the gastrointestinal tract. The role of gastrointestinal degradation in the toxic effects of DBPs still needs further investigation. In this study, the degradation of five categories of DBPs (22 DBPs) in the stomach and small intestine was investigated based on a semicontinuous steady-state gastrointestinal simulation system, and 22 DBPs can be divided into three groups based on their residual proportions. The degradation of chloroacetonitrile (CAN), dibromoacetic acid (DBAA), and tetrabromopyrrole (FBPy) was further analyzed based on the Simulator of the Human Intestinal Microbial Ecosystem inoculating the gut microbiota, and approximately 60% of CAN, 45% of DBAA, and 80% of FBPy were degraded in the stomach and small intestine, followed by the complete degradation of remaining DBPs in the colon. Meanwhile, gastrointestinal degradation can reduce oxidative stress-mediated DNA damage and apoptosis induced by DBPs in DLD-1 cells, but the toxicity of DBPs did not disappear with the complete degradation of DBPs, possibly because of their interferences on gut microbiota. This study provides new insights into investigating the gastrointestinal toxic effects and mechanisms of DBPs through oral exposure.

2,5-Hexanedione Affects Ovarian Granulosa Cells in Swine by Regulating the CDKN1A Gene: A Transcriptome Analysis

N-hexane, a common industrial organic solvent, causes multiple organ damage owing to its metabolite, 2,5-hexanedione (2,5-HD). To identify and evaluate the effects of 2,5-HD on sows’ reproductive performance, we used porcine ovarian granulosa cells (pGCs) as a vehicle and carried out cell morphology and transcriptome analyses. 2,5-HD has the potential to inhibit the proliferation of pGCs and induce morphological changes and apoptosis depending on the dose. RNA-seq analyses identified 4817 differentially expressed genes (DEGs), with 2394 down-regulated and 2423 up-regulated following 2,5-HD exposure treatment. The DEG, cyclin-dependent kinase inhibitor 1A (CDKN1A), according to the Kyoto Encyclopedia of Genes and Genomes enrichment analysis, was significantly enriched in the p53 signaling pathway. Thus, we evaluated its function in pGC apoptosis in vitro. Then, we knocked down the CDKN1A gene in the pGCs to identify its effects on pGCs. Its knockdown decreased pGC apoptosis, with significantly fewer cells in the G1 phase (p < 0.05) and very significantly more cells in the S phase (p < 0.01). Herein, we revealed novel candidate genes that influence pGCs apoptosis and cell cycle and provided new insights into the role of CDKN1A in pGCs during apoptosis and cell cycle arrest.

In vitro expansion of hematopoietic stem cells in a porous hydrogel-based 3D culture system

Hematopoietic stem cell (HSC) transplantation remains the most effective therapy for hematologic and lymphoid disorders. However, as the primary therapeutic cells, the source of HSCs has been limited due to the scarcity of matched donors and difficulties in ex vivo expansion. Here, we described a facile method to attempt the expansion of HSCs in vitro through a porous alginate hydrogel-based 3D culture system. We used gelatin powders as the porogen to create submillimeter-scaled pores in alginate gel bulk while pre-embedding naïve HSCs in the gel phase. The results indicated that this porous hydrogel system performed significantly better than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogels in maintaining the phenotype and renewability of HSCs. Only the porous hydrogel system achieved a two-fold growth of CD34+ cells within seven days of culture, while the number of CD34+ cells in the suspension system and nonporous hydrogel showed different degrees of attenuation. The expansion efficiency of the porous hydrogel for CD34+CD38- cells was more than 2.2 times that of the other two systems. Mechanistic study via biophysical analysis revealed that the porous alginate system was competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, thus maintaining the cellular phenotype of the CD34+ cells. The transcriptomic analysis further suggested that the porous alginate system also upregulated the TNF signaling pathway and activated the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that renewability was substantially favoured. STATEMENT OF SIGNIFICANCE: • The reported porous hydrogel system performs significantly better in terms of maintaining the phenotype and renewability of HSCs than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogel. • The reported porous alginate system is competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, and therefore maintain the cellular phenotype of the CD34+ cells. • The reported porous alginate system can also upregulate the TNF signaling pathway and activate the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that the renewability is substantially favored..

Min pig skeletal muscle response to cold stress

The increased sensitivity of pigs to ambient temperature is due to today’s intensive farming. Frequent climate disasters increase the pressure on healthy pig farming. Min pigs are an indigenous pig breed in China with desirable cold resistance characteristics, and hence are ideal for obtaining cold-resistant pig breeds. Therefore, it is important to discover the molecular mechanisms that are activated in response to cold stress in the Min pig. Here, we conducted a transcriptomic analysis of the skeletal muscle of Min pigs under chronic low-temperature acclimation (group A) and acute short cold stress (group B). Cold exposure caused more genes to be upregulated. Totals of 125 and 96 differentially expressed genes (DEGs) were generated from groups A and B. Sixteen common upregulated DEGs were screened; these were concentrated in oxidative stress (SRXN1, MAFF), immune and inflammatory responses (ITPKC, AREG, MMP25, FOSL1), the nervous system (RETREG1, GADD45A, RCAN1), lipid metabolism (LRP11, LIPG, ITGA5, AMPD2), solute transport (SLC19A2, SLC28A1, SLCO4A1), and fertility (HBEGF). There were 102 and 73 genes that were specifically differentially expressed in groups A and B, respectively. The altered mRNAs were enriched in immune, endocrine, and cancer pathways. There were 186 and 91 differentially expressed lncRNAs generated from groups A and B. Analysis of the target genes suggested that they may be involved in regulating the MAPK signaling pathway for resistance to cold. The results of this study provide a comprehensive overview of cold exposure–induced transcriptional patterns in skeletal muscle of the Min pig. These results can guide future molecular studies of cold stress response in pigs for improving cold tolerance as a goal in breeding programs.

Sulfiredoxin-1 protects retinal ganglion cells from high glucose-induced oxidative stress and inflammatory injury by potentiating Nrf2 signaling via the Akt/GSK-3β pathway

Sulfiredoxin-1 (Srxn1) has been acknowledged as a remarkable pro-survival factor in the protection of cells against stress-induced damage. The persistent exposure of retinal ganglion cells (RGCs) to high glucose (HG) in diabetes induces cellular damage, which contributes to the onset of diabetic retinopathy, a severe complication of diabetes. So far, little is known about the role of Srxn1 in regulating HG-induced injury of RGCs. The goals of this work were to evaluate the possible relevance of Srxn1 in the modulation of HG-induced apoptosis, oxidative stress and inflammation of RGCs in vitro. Our data showed that HG exposure caused a marked decrease in Srxn1 expression in RGCs. The up-regulation of Srxn1 markedly decreased HG-evoked apoptosis, reactive oxygen species (ROS) generation and pro-inflammatory cytokine release in RGCs. On the contrary, the depletion of Srxn1 rendered RGCs more susceptible to HG-induced injury. Further data demonstrated that Srnx1 enhanced the activation of nuclear factor erythroid-2 (E2)-related factor 2 (Nrf2) signaling in HG-exposed RGCs associated with up-regulating the phosphorylation of Akt and glucogen synthase kinase-3β (GSK-3β). Notably, the inhibition of Akt abolished Srnx1-overexpression-mediated Nrf2 activation, while GSK-3β inhibition reversed Srnx1-depletion-mediated inactivation of Nrf2. In addition, Nrf2 inhibition partially abrogated Srnx1-mediated protective effects against HG-induced injury of RGCs. In summary, these data demonstrate that the overexpression of Srxn1 protects RGCs from the HG-induced injury of RGCs by enhancing Nrf2 signaling via modulation of Akt/GSK-3β axis. Our work highlights that the Srxn1-mediated Akt/GSK-3β/Nrf2 axis may exert a possible role in regulating RGC injury of diabetic retinopathy.

Hyperoxidation of Peroxiredoxins and Effects on Physiology of Drosophila

The catalytic activity of peroxiredoxins (Prx) is determined by the conserved peroxidatic cysteine (Cys_P), which reacts with peroxides to form sulfenic acid (Cys-SOH). Under conditions of oxidative stress, Cys_P is oxidized to catalytically inactive sulfinic (Cys-SO₂) and sulfonic (Cys-SO₃) forms. The Cys-SO₂ form can be reduced in a reaction catalyzed by sulfiredoxin (Srx). To explore the physiological significance of peroxiredoxin overoxidation, we investigated daily variations in the oxidation state of 2-Cys peroxiredoxins in flies of different ages, or under conditions when the pro-oxidative load is high. We found no statistically significant changes in the 2-Cys Prxs monomer:dimer ratio, which indirectly reflects changes in the Prx catalytic activity. However, we found daily variations in Prx-SO_2/3 that were more pronounced in older flies as well as in flies lacking Srx. Unexpectedly, the srx mutant flies did not exhibit a diminished survivorship under normal or oxidative stress conditions. Moreover, the srx mutant was characterized by a higher physiological activity. In conclusion, catalytically inactive forms of Prx-SO_2/3 serve not only as a marker of cellular oxidative burden, but may also play a role in an adaptive response, leading to a positive effect on the physiology of Drosophila melanogaster.

IRLnc: a novel functional noncoding RNA contributes to intramuscular fat deposition

Background

Intramuscular fat (IMF) is associated with meat quality and insulin resistance in animals. Research on genetic mechanism of IMF decomposition has positive meaning to pork quality and diseases such as obesity and type 2 diabetes treatment. In this study, an IMF trait segregation population was used to perform RNA sequencing and to analyze the joint or independent effects of genes and long intergenic non-coding RNAs (lincRNAs) on IMF.

Results

A total of 26 genes including six lincRNA genes show significantly different expression between high- and low-IMF pigs. Interesting, one lincRNA gene, named IMF related lincRNA (IRLnc) not only has a 292-bp conserved region in 100 vertebrates but also has conserved up and down stream genes (< 10 kb) in pig and humans. Real-time quantitative polymerase chain reaction (RT-qPCR) validation study indicated that nuclear receptor subfamily 4 group A member 3 (NR4A3) which located at the downstream of IRLnc has similar expression pattern with IRLnc. RNAi-mediated loss of function screens identified that IRLnc silencing could inhibit both of the RNA and protein expression of NR4A3. And the in-situ hybridization co-expression experiment indicates that IRLnc may directly binding to NR4A3. As the NR4A3 could regulate the catecholamine catabolism, which could affect insulin sensitivity, we inferred that IRLnc influence IMF decomposition by regulating the expression of NR4A3.

Conclusions

In conclusion, a novel functional noncoding variation named IRLnc has been found contribute to IMF by regulating the expression of NR4A3. These findings suggest novel mechanistic approach for treatment of insulin resistance in human beings and meat quality improvement in animal.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07349-5.

GLUT1-mediated glycolysis supports GnRH-induced secretion of luteinizing hormone from female gonadotropes

The mechanisms mediating suppression of reproduction in response to decreased nutrient availability remain undefined, with studies suggesting regulation occurs within the hypothalamus, pituitary, or gonads. By manipulating glucose utilization and GLUT1 expression in a pituitary gonadotrope cell model and in primary gonadotropes, we show GLUT1-dependent stimulation of glycolysis, but not mitochondrial respiration, by the reproductive neuropeptide GnRH. GnRH stimulation increases gonadotrope GLUT1 expression and translocation to the extracellular membrane. Maximal secretion of the gonadotropin Luteinizing Hormone is supported by GLUT1 expression and activity, and GnRH-induced glycolysis is recapitulated in primary gonadotropes. GLUT1 expression increases in vivo during the GnRH-induced ovulatory LH surge and correlates with GnRHR. We conclude that the gonadotropes of the anterior pituitary sense glucose availability and integrate this status with input from the hypothalamus via GnRH receptor signaling to regulate reproductive hormone synthesis and secretion.

Reactive oxygen species in male reproduction: A boon or a bane?

Reactive oxygen species (ROS) are free radicals derived from oxygen during normal cellular metabolism. ROS play a crucial role in the physiological processes and signalling pathways associated with male fertility. At physiological concentrations, ROS act as molecular mediators of signal transduction pathways involved in the regulation of the hypothalamic-pituitary-gonadal axis, spermatogenesis and steroidogenesis. They also trigger the morphological changes required for sperm maturation, such as DNA compaction and flagellar modification. Furthermore, ROS modulate crucial processes involved in the attainment of sperm fertilising ability such as capacitation, hyperactivation, acrosome reaction and sperm-oocyte fusion. Conversely, oxidative stress prevails when the concentration of ROS overwhelms the body's antioxidant defence. Various endogenous and exogenous factors enhance the synthesis of ROS resulting in the disruption of structural and functional integrity of spermatozoa through the induction of apoptotic pathway and oxidation of molecules, such as lipids, proteins and DNA. Therefore, maintenance of a balanced redox state is critical for normal male reproductive functions. This article discusses the dual role of ROS in male reproduction, highlighting the physiological role as well as their pathological implications on male fertility.