Differential actions of diacylglycerol acyltransferase (DGAT) 1 and 2 in regulating lipid metabolism and progesterone secretion of goose granulosa cells

Insights into the molecular mechanisms of lipid transformation in sturgeon fillets: Interplay between specific spoilage and dominant bacteria

This study investigates spoilage bacteria's impact on lipid metabolism in sturgeon fillets using UHPLC-Q-Orbitrap-MS/MS-based untargeted lipidomic analysis. A total of 4041 lipid molecules across five classes and 42 subclasses were identified, including glycerophospholipids (GPs, 50.88%), glycerolipids (GLs, 36.08%), sphingolipids (SPs, 10.47%), fatty acyls (FAs, 2.45%), and sterol lipids (STs, 0.12%). Aeromonas sobria, a specific spoilage bacterium, reduced GPs and FAs while increasing GLs, SPs, and STs via extracellular lipases and esterases. Acinetobacter albensis, the dominant bacterium, mainly elevated SPs and FAs. Their interaction promoted lipid metabolism and oxidation while producing volatile organic compounds (VOCs). Ethyl isobutyrate, ethyl propionate, isobutyl formate, pentan-2-one, propan-2-one, 2-butanone, 3-methyl-3-buten-1-ol, and dimethyl sulfide were mainly associated with Acinetobacter albensis, while 1-hexanol, 1-pentanol, 1-penten-3-ol, 1-hydroxypropan-2-one, 3-methyl-1-butanol, 2-methylbutanal, 3-hydroxy-2-butanone, and propionaldehyde were mainly related to Aeromonas sobria. This work unveils the mechanism of lipid transformation in sturgeon fillets during refrigerated storage, offering insights for aquatic products quality control.

CTBP1 links metabolic syndrome to polycystic ovary syndrome through interruption of aromatase and SREBP1

Some patients with polycystic ovarian syndrome (PCOS) suffered from metabolic syndrome (MetS) including dyslipidemia, hyperinsulinism, but the underlying mechanism is unclear. Although C-terminal Binding Protein 1 (CTBP1) is a transcriptional co-repressor frequently involved in hormone secretion disorders and MetS-associated diseases, the role of CTBP1 in PCOS is rarely reported. In the present study, we found that CTBP1 expression was significantly elevated in primary granulosa cells (pGCs) derived from the PCOS with MetS patients and was positively associated with serum triglyceride, but negatively correlated with serum estradiol (E2) or high-density lipoprotein. Mechanistic study suggested that CTBP1 physically bound to the promoter II of cytochrome P450 family 19 subfamily A member 1 (CYP19A1) to inhibit the aromatase gene transcription and expression, resulting in the reduced E2 synthesis. Moreover, CTBP1 interacted with the phosphorylated SREBP1a at S396 in nuclei, leading to the FBXW7-dependent protein degradation, resulting in the reduced lipid droplets formation in pGCs. Therefore, we conclude that CTBP1 in GCs dysregulates the synthesis of steroid hormones and lipids through suppression of aromatase expression and promotion of SREBP1a protein degradation in PCOS patients, which may offer some fresh insights into the potential pathological mechanism for this tough disease.

DUSP8-attenuated ERK1/2 signaling mediates lipogenesis and steroidogenesis in chicken granulosa cells

The lipogenesis and steroidogenesis of granulosa cells are crucial during follicular development, yet it remains unclear whether dual-specificity phosphatase 8 (DUSP8) is involved. In this study, the specific role of DUSP8 in lipogenesis and steroidogenesis was investigated through culturing chicken granulosa cells in vitro. The results revealed that the expression levels of adipogenic genes were elevated after DUSP8 overexpression and reduced after knockdown. The same was observed for lipid deposition in granulosa cells. Meanwhile, the steroidogenic gene expression and progesterone synthesis were promoted after DUSP8 overexpression and inhibited after knockdown. In addition, we also found that DUSP8 blocked the phosphorylation of extracellular regulatory kinase 1/2 (ERK1/2). Based on the previous results that activated ERK1/2 signaling inhibited lipid deposition and progesterone synthesis in chicken granulosa cells, we demonstrated that DUSP8 promoted lipid deposition and progesterone synthesis through mediating the ERK1/2 signaling pathway. The results will improve our understanding of the molecular regulatory mechanisms regarding lipid metabolism and progesterone synthesis in chicken granulosa cells.

Potential Role of Lauric Acid in Milk Fat Synthesis in Chinese Holstein Cows Based on Integrated Analysis of Ruminal Microbiome and Metabolome

The composition and metabolic profile of the ruminal microbiome have an impact on milk composition. To unravel the ruminal microbiome and metabolome affecting milk fat synthesis in dairy cows, 16S rRNA and internal transcribed spacer (ITS) gene sequencing, as well as ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) methods were used to investigate the significant differences in ruminal bacterial and fungal communities as well as metabolome among Chinese Holstein cows with contrasting milk fat contents under the same diet (H-MF 5.82 ± 0.41% vs. L-MF 3.60 ± 0.12%). Another objective was to culture bovine mammary epithelial cells (BMECs) to assess the effect of metabolites on lipid metabolism. Results showed that the acetate-to-propionate ratio and xylanase activity in ruminal fluid were both higher in H-MF. Microbiome sequencing identified 10 types of bacteria and four types of fungi differently abundant at the genus level. Metabolomics analysis indicated 11 different ruminal metabolites between the two groups, the majority of which were lipids and organic acids. Among these, lauric acid (LA) was enriched in fatty acid biosynthesis with its concentration in milk fat of H-MF cows being greater (217 vs. 156 mg per 100 g milk), thus, it was selected for an in vitro study with BMECs. Exogenous LA led to a marked increase in intracellular triglyceride (TG) content and lipid droplet formation, and it upregulated the mRNA abundance of fatty acid uptake and activation (CD36 and ACSL1), TG synthesis (DGAT1, DGAT2 and GPAM), and transcriptional regulation (SREBP1) genes. Taken together, the greater relative abundance of xylan-fermenting bacteria and fungi, and lower abundance of bacteria suppressing short-chain fatty acid-producing bacteria or participating in fatty acid hydrogenation altered lipids and organic acids in the rumen of dairy cows. In BMECs, LA altered the expression of genes involved in lipid metabolism in mammary cells, ultimately promoting milk fat synthesis. Thus, it appears that this fatty acid plays a key role in milk fat synthesis.

Leptin signalling regulates transcriptional differences in granulosa cells from genetically obese mice but not the activation of NLRP3 inflammasome

Obesity is associated with increased ovarian inflammation and the establishment of leptin resistance. We presently investigated the role of impaired leptin signalling on transcriptional regulation in granulosa cells (GCs) collected from genetically obese mice. Furthermore, we characterised the association between ovarian leptin signalling, the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome and macrophage infiltration in obese mice. After phenotype characterisation, ovaries were collected from distinct group of animals for protein and mRNA expression analysis: (i) mice subjected to a diet-induced obesity (DIO) protocol, where one group was fed a high-fat diet (HFD) and another a standard chow diet (CD) for durations of 4 or 16 weeks; (ii) mice genetically deficient in the long isoform of the leptin receptor (ObRb; db/db); (iii) mice genetically deficient in leptin (ob/ob); and (iv) mice rendered pharmacologically hyperleptinemic (LEPT). Next, GCs from antral follicles isolated from db/db and ob/ob mice were subjected to transcriptome analysis. Transcriptional analysis revealed opposing profiles in genes associated with steroidogenesis and prostaglandin action between the genetic models, despite the similarities in body weight. Furthermore, we observed no changes in the mRNA and protein levels of NLRP3 inflammasome components in the ovaries of db/db mice or in markers of M1 and M2 macrophage infiltration. This contrasted with the downregulation of NLRP3 inflammasome components and M1 markers in ob/ob and 16-wk HFD-fed mice. We concluded that leptin signalling regulates NLRP3 inflammasome activation and the expression of M1 markers in the ovaries of obese mice in an ObRb-dependent and ObRb-independent manner. Furthermore, we found no changes in the expression of leptin signalling and NLRP3 inflammasome genes in GCs from db/db and ob/ob mice, which was associated with no effects on macrophage infiltration genes, despite the dysregulation of genes associated with steroidogenesis in homozygous obese db/db. Our results suggest that: (i) the crosstalk between leptin signalling, NLRP3 inflammasome and macrophage infiltration takes place in ovarian components other than the GC compartment; and (ii) transcriptional changes in GCs from homozygous obese ob/ob mice suggest structural rearrangement and organisation, whereas in db/db mice the impairment in steroidogenesis and secretory activity.

High expression of miR-22-3p in chicken hierarchical follicles promotes granulosa cell proliferation, steroidogenesis, and lipid metabolism via PTEN/PI3K/Akt/mTOR signaling pathway

MicroRNAs (miRNAs) are a class of RNA macromolecules that play regulatory roles in follicle development by inhibiting protein translation through binding to the 3'UTR of its target genes. Granulosa cell (GC) proliferation, steroidogenesis, and lipid metabolism have indispensable effect during folliculogenesis. In this study, we found that miR-22-3p was highly expressed in the hierarchical follicles of the chickens, which indicated that it may be involved in follicle development. The results obtained suggested that miR-22-3p promoted proliferation, hormone secretion (progesterone and estrogen), and the content of lipid droplets (LDs) in the chicken primary GC. The results from the bioinformatics analysis, luciferase reporter assay, qRT-PCR, and Western blotting, confirmed that PTEN was directly targeted to miR-22-3p. Subsequently, it was revealed that PTEN inhibited proliferation, hormone secretion, and the content of LDs in GC. Therefore, this study showed that miR-22-3p could activate PI3K/Akt/mTOR pathway via targeting PTEN. Taken together, the findings from this study indicated that miR-22-3p was highly expressed in the hierarchical follicles of chickens, which promotes GC proliferation, steroidogenesis, and lipid metabolism by repressing PTEN to activate PI3K/AKT/mTOR pathway.

Review: genetic background of milk fatty acid synthesis in bovines

Milk fat composition is an important trait for the dairy industry as it directly influences the nutritional and technological properties of milk and other dairy products. The synthesis of milk fat is a complex process regulated by a network of genes. Thus, understanding the genetic variation and molecular mechanisms regulating milk fat synthesis will help to improve the nutritional quality of dairy products. In this review, we provide an overview of milk fat synthesis in bovines along with the candidate genes involved in the pathway. We also discuss de novo synthesis of fatty acids (ACSS, ACACA, FASN), uptake of FAs (FATP, FAT, LPL), intracellular activation and channelling of FAs (ACSL, FABP), elongation (EVOLV6), desaturation (SCD, FADS), formation of triglycerides (GPAM, AGPAT, LIPIN, DGAT), and milk lipid secretion (BTN1A1, XDH, PLIN2). The genetic variability of individual fatty acids will help to develop selection strategies for obtaining a healthier milk fat profile in bovines. Thus, this review will offer a potential understanding of the molecular mechanisms that regulate milk fat synthesis in bovines.

Lipid Deposition and Progesterone Synthesis Are Increased by miR-181b-5p through RAP1B/ERK1/2 Pathway in Chicken Granulosa Cells

Steroid hormones secreted by granulosa cells are essential for maintaining normal development of chicken follicles. Our previous sequencing data indicated that miR-181b-5p and RAS-related protein 1B (RAP1B) appeared to function in chicken granulosa cells, which was further explored in this study. The results suggested that miR-181b-5p facilitated the aggregation of lipid droplets and the synthesis of progesterone. In contrast, RAP1B astricted lipid deposition and progesterone secretion. Cotransfection of the RAP1B overexpression vector with miR-181b-5p mimic eliminated the promoting effect of miR-181b-5p. Dual-luciferase reporter assay confirmed that miR-181b-5p bound directly to the 3' untranslated region (3' UTR) of RAP1B. We also found that miR-181b-5p and RAP1B reduced and enhanced the phosphorylation levels of extracellular signal-regulated kinases 1 and 2 (ERK1/2), respectively. The application of ERK1/2 activators and inhibitors demonstrated that ERK1/2 is a negative regulator of lipid deposition and progesterone synthesis. In conclusion, we revealed that miR-181b-5p accelerated lipid deposition and progesterone synthesis through the RAP1B/ERK1/2 pathway in chicken granulosa cells. miR-181b-5p and RAP1B may serve as new biomarkers in breeding to improve chicken reproductive performance and prevent ovary-related diseases.

Estrogen Receptor Gene 1 (ESR1) Mediates Lipid Metabolism in Goose Hierarchical Granulosa Cells Rather than in Pre-Hierarchical Granulosa Cells

(1) Background: The role of estrogen receptor gene 1 (ESR1) in female reproduction and lipid metabolism has been extensively investigated. However, its contribution to lipid metabolism during the development of poultry follicles remains unclear. (2) Methods: This study aimed to explore the function of ESR1 via overexpressing (ESR1^ov) and interfering (ESR1^si) with its expression in pre-hierarchical granulosa cells (phGCs) and hierarchical granulosa cells (poGCs). (3) Results: We successfully cloned and obtained an 1866 bp segment of the full-length CDS region of the Sichuan white goose ESR1 gene. In phGCs of the ESR1^ov and ESR1^si groups, there were no significant changes compared to the control group. However, in poGCs, the ESR1^ov group exhibited decreased lipid deposition, triglycerides, and cholesterol compared to the control group, while the ESR1^si group showed increased lipid deposition, triglycerides, and cholesterol. The expression of APOB and PPARα was significantly reduced in the ESR1^ov group compared to the ESR1^ov-NC group. Moreover, significant changes in the expression of ACCα, DGAT1, SCD, CPT1, and ATGL were observed between the ESR1^si and ESR1^si-NC group. (4) Conclusions: These findings shed light on the function and molecular mechanism of ESR1 in lipid metabolism in goose poGCs, providing a better understanding of the physiological process of goose follicular development.

miR-128-3p regulates chicken granulosa cell function via 14-3-3β/FoxO and PPAR-γ/LPL signaling pathways

MicroRNAs (miRNAs) are class of 22 nt short RNA sequences which inhibit protein translation through binding to the 3'UTR of its target genes. The continuous ovulatory property of chicken follicle makes it a perfect model for studying granulosa cell (GC) functions. In this study, we found that large number of miRNAs including miR-128-3p, were differentially expressed in the GCs of F1 and F5 follicles of chicken. Subsequently, the results revealed that miR-128-3p inhibited proliferation, the formation of lipid droplets, and hormone secretion in chicken primary GCs through directly targeting YWHAB and PPAR-γ genes. To determine the effects of 14-3-3β (encoded by YWHAB) protein on GCs functions, we overexpressed or inhibited the expression of YWHAB, and the results showed that YWHAB inhibited the function of FoxO proteins. Collectively, we found that miR-128-3p was highly expressed in the chicken F1 follicles compared to the F5 follicles. In addition, the results indicated that miR-128-3p promoted GC apoptosis through 14-3-3β/FoxO pathway via repressing YWHAB, and inhibited lipid synthesis by impeding the PPAR-γ/LPL pathway, as well as reduced the secretion of progesterone and estrogen. Taken together, the results showed that miR-128-3p plays a regulatory role in chicken granulosa cell function via 14-3-3β/FoxO and PPAR-γ/LPL signaling pathways.

Overexpression of DGAT2 Regulates the Differentiation of Bovine Preadipocytes

Triacylglycerols (TAGs) are a major component of intramuscular fat. Diacylglycerol O-acyltransferase 2(DGAT2) expression determines the rate of TAG synthesis. The purpose of this study was to investigate the role of DGAT2 in the differentiation of Yanbian cattle preadipocytes and lipid metabolism-related signalling pathways. Bovine preadipocytes were infected with overexpression and interfering adenovirus vectors of DGAT2. The effects on the differentiation of Yanbian cattle preadipocytes were examined using molecular and transcriptomic techniques, including differentially expressed genes (DEGs) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis. DGAT2 overexpression significantly increased (p < 0.05) intracellular TAG, adiponectin, and lipid droplet (LD) contents. Moreover, it upregulated (p < 0.05) peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α, and fatty acid binding protein 4 mRNA expression. In contrast, DGAT2 knockdown reduced intracellular TAG and LD content and downregulated (p < 0.05) C/EBPβ, mannosyl (alpha-1,3-)-glycoproteinbeta-1,2-N-acetylglucosaminyltransferase, lipin 1,1-acylglycerol-3-phosphate O-acyltransferase 4, and acetyl-CoA carboxylase alpha mRNA expression. Between DGAT2-overexpressing preadipocytes and normal cells, 208 DEGs were identified, including 106 upregulated and 102 downregulated genes. KEGG pathway analysis revealed DEGs mainly enriched in PPAR signalling and AMP-activated protein kinase pathways, cholesterol metabolism, and fatty acid biosynthesis. These results demonstrated that DGAT2 regulated preadipocyte differentiation and LD and TAG accumulation by mediating the expression of adipose differentiation-, lipid metabolism-, and fatty acid synthesis-related genes.

Molecular characterisation and expression profile of the PRLR gene during goose ovarian follicle development

1. Although PRL-PRLR signalling plays important roles in regulating avian reproduction, there is a paucity of information regarding the functional significance of PRLR in goose ovarian follicle development.2. The full-length 2,496 bp coding sequence of PRLR was obtained from Sichuan White goose (Anser cygnoides) for the first time and was seen to encode a polypeptide containing 831 amino acids. Goose PRLR shares similar sequence characteristics and conserved functional domains to other avian species and was phylogenetically clustered into the avian clade.3. The qPCR results suggested that the mRNA levels of PRLR significantly increased in primary follicles during weeks 3 to 4 of age and were higher in secondary- than in primordial follicles at week 5 post-hatching, which suggested that the PRLR-mediated signalling could be involved in regulation of early folliculogenesis.4. The PRLR mRNA was expressed at the highest levels in the prehierarchical 8-10 mm granulosa layers throughout goose ovarian follicle development, indicating a role for PRLR in the process of follicle selection.5. PRLR mRNA was differentially expressed in the three cohorts of in vitro cultured granulosa cells harvested from different sized goose ovarian follicles, which suggested that PRLR was involved in regulating granulosa cell functions depending on the stage of follicle development. These data provide novel insights into the role of PRLR during goose ovarian follicle development, although the underlying mechanisms await further investigations.

miR-27b-3p inhibits estrogen secretion of goose granulosa cells by targeting CYP1B1 through the AMPK signaling pathway

Although miR-27b-3p has been evidenced to regulate the proliferation, apoptosis, and differentiation of a variety of mammalian cell types, its actions and mechanisms on ovarian cell steroidogenesis remains largely unknown in both mammalian and avian species. In this study, we aimed to determine the expression profiles of miR-27b-3p in granulosa cell layers during goose ovarian follicle development and to reveal its actions on estrogen (E₂) secretion of goose granulosa cells as well as the underlying regulatory mechanisms. It was observed that miR-27b-3p was ubiquitously expressed throughout follicle development but exhibited much higher levels in hierarchical- than in prehierarchical follicles. In cultured granulosa cells from the fourth through second largest preovulatory (F4-F2) follicles of goose, up- and downregulation of miR-27b-3p by using its mimic and inhibitor significantly decreased and increased E₂ secretion, respectively. Meanwhile, the mRNA levels of STAR and CYP19A1 were significantly reduced while those of CYP11A1 and 3βHSD were elevated in the mimic-transfected granulosa cells. By comparison, downregulation of miR-27b-3p enhanced the mRNA levels of STAR but had no significant effects on those of CYP19A1, CYP11A1, and 3βHSD. Results from bioinformatic prediction and luciferase reporter assay demonstrated that CYP1B1 was a downstream target of miR-27b-3p. Although the siRNA-mediated downregulation of CYP1B1 did not significantly change E₂ secretion by goose granulosa cells, it reduced the mRNA levels of STAR and CYP19A1 as well as those of LKB1 and AMPKα, which are involved in the AMPK signaling pathway. Taken together, these data suggest that miR-27b-3p plays an inhibitory role in E₂ secretion by goose F4-F2 granulosa cells, at least in part, by targeting CYP1B1 through the AMPK signaling pathway.

Overexpression of DGAT2 Stimulates Lipid Droplet Formation and Triacylglycerol Accumulation in Bovine Satellite Cells

Intramuscular fat (IMF) is closely related to the tenderness, juiciness, and flavor of beef, and is an important indicator for beef quality assessment internationally. The main components of skeletal intramuscular fat (IMF) are phospholipids and triacylglycerols (TAG), and the final step of TAG biosynthesis is catalyzed by diacylglycerol acyltransferase 2 (DGAT2). To explore the effect of DGAT2 on the differentiation of bovine muscle satellite cells (BSCs) and its role in the signaling pathway related to lipid metabolism, the adenovirus overexpression and interference vector of the DGAT2 gene was constructed in this study, and the overexpression adenovirus Ad-DGAT2 and interfering adenovirus sh-DGAT2 were used to infect BSCs. Overexpression of DGAT2 resulted in a significant increase in the contents of TAG and ADP, and the mRNA and protein expression levels of PPARγ, C/EBPα, and SREBF1 (p < 0.05). Interfering with the expression of DGAT2 reduced the intracellular TAG content and lipid droplet accumulation. Furthermore, the mRNA and protein expression levels of PPARγ, C/EBPα, and SREBF1 (p < 0.05) were significantly downregulated. Transcriptome sequencing showed that a total of 598 differentially expressed genes (DEGs) were screened in BSCs infected with Ad-DGAT2, and these DEGs included 292 upregulated genes and 306 downregulated genes. A total of 49 DEGs were screened in BSCs infected with sh-DGAT2, and these DEGs included 25 upregulated and 24 downregulated genes. KEGG enrichment analysis showed that the DEGs, after overexpression of DGAT2, were mainly enriched in the PPAR signaling pathway, and the fat digestion and absorption, glycerophospholipid metabolism, fatty acid biosynthesis, and AMPK signaling pathways. The DEGs obtained after interfering with DGAT2 were mainly enriched in the metabolic pathways, such as the PPAR signaling pathway and PI3K/AKT signaling pathway. In summary, our study demonstrated that the lipid droplet formation, TAG accumulation, and adipogenic gene expression in BSCs overexpressing DGAT2 were higher than those in the control cells. These results highlight the important role of DGAT2 in regulating BSCs during adipogenic transdifferentiation and underscore the complexity of intramuscular adipogenesis.

UHPLC-Q-Exactive Orbitrap MS/MS-based untargeted lipidomics reveals molecular mechanisms and metabolic pathways of lipid changes during golden pomfret (Trachinotus ovatus) fermentation

Fermented golden pomfret (a popular marine fish product) is prepared via spontaneous fermentation. However, no comprehensive analysis has been reported on its lipid composition and metabolism. Herein, UHPLC-MS/MS-based untargeted lipidomic analysis identified 998 lipids (six classes; 29 subclasses) in fermented golden pomfret, including glycerolipids (47.70%) and glycerophospholipids (32.06%). As fermentation proceeded, triglyceride and diglyceride contents increased and subsequently decreased, while that of poly-unsaturated fatty acid-containing lipids increased (including those with docosahexaenoic acid, eicosapentaenoic acid, and docosapentaenoic acid). Pathway enrichment analysis identified seven lipid-related metabolic pathways, with the glycerophospholipid pathway found to be the most pertinent. Moreover, the decreased abundance of phosphatidylethanolamines and phosphatidylcholines during fermentation results from their high unsaturated fatty acid (FA) content. Indeed, essential FA contents increase following fermentation, due to their occurrence as glycerolipid side chains. Collectively, the results of this study provide a theoretical reference for optimizing the quality of fermented fish products.

Heat-Killed Enterococcus faecalis EF-2001 Attenuate Lipid Accumulation in Diet-Induced Obese (DIO) Mice by Activating AMPK Signaling in Liver

To explore the inhibitory mechanism of heat-killed Enterococcus faecalis, EF-2001 on hepatic lipid deposition, a diet-induced obese (DIO) animal model was established by high-fat diet (HFD). The DIO C57BL/6 mice were divided into four groups: the normal group without HFD (ND, n = 8), obesity group (HFD, n = 8), experimental group (HFD + EF-2001, 200 mg/kg, n = 8), and positive control group (HFD + Orlistat, 60 mg/kg, n = 8). After 4 weeks, liver and adipose tissue were fixed in 10% paraformaldehyde, followed by embedding in paraffin for tissue sectioning. The differences in body mass, body fat ratio, fatty cell area, and lipid profiling of the liver (TC, LDL, and HDL) were also determined. Moreover, Western blot was performed to analyze the expression of lipid accumulation-related proteins, including AMPK, PPARγ, SREBP-1, ACC, and FAS. Compared with the HFD group, the HFD + EF-2001 group exhibited decreased fat mass, liver index, adipocyte area, TC, and LDL, and an increased level of HDL. The results of liver hematoxylin and eosin (H&E), and oil red O staining showed that the mice in each intervention group were improved on hepatic lipid accumulation, and the mice in the HFD + EF-2001 group were the most similar to those in the normal group when compared with the HFD group. From the Western blot results, we proved that EF-2001 activated the AMPK signaling pathway. EF-2001 significantly upregulated the expressions of p-AMPK and p-ACC and downregulated PPARγ, SREBP-1, and FAS in murine liver. Taken together, these results suggest that EF-2001 decrease lipid accumulation in the DIO model mice through the AMPK pathway and ameliorate liver damage by HFD.

Effect of Gender to Fat Deposition in Yaks Based on Transcriptomic and Metabolomics Analysis

Fat deposition in yaks plays an important part in survival, multiplication, and meat quality. In this work, the characteristic of fat deposition in male yaks (MYs) and female yaks (FYs) and the regulations of gender to yak fat deposition were explored by mRNA-Seq and non-targeted metabolomics analyses. FYs possessed a higher body fat rate (BFR) of visceral fat, fat content in longissimus dorsi (LD) and liver, and subcutaneous fat thickness (p < 0.05). The fat and cholesterol synthesis in liver and the fat transport in FY blood increased. The fat metabolism in yaks is the combined effect of carbohydrate, fatty acid, and amino acid metabolism by tricarboxylic acid (TCA) cycle, and an increase of triglyceride (TG) synthesis was accompanied by an increase of steroid synthesis. The high levels of myo-inositol and cortisol (COR) (p < 0.01) activated the calcium signaling in FY subcutaneous fat, followed by the increase of adipocyte secretion, and resulted in more leptin (LEP) secretion (p < 0.01). Then peroxisome proliferator-activated receptor (PPAR) signaling was activated by the focal adhesions and ECM-receptor interaction. Finally, the TG and steroid synthesis increased by the expression regulation of ME1, SCD, ELOVL6, DGAT2, DBI, LPL, CPT1, PLIN1, LIPA, DHCR24, and SQLE gene. The above genes can be considered as the candidate genes for yak with higher fat amount in molecular breeding in the future. This study can provide a theoretical basis for improving the meat quality and breeding of yaks.

Systematic Analysis of Long Noncoding RNA and mRNA in Granulosa Cells during the Hen Ovulatory Cycle

Simple Summary

Chicken is one of the most economically important farm poultry, and providing many food products, such as meat and eggs for human consumption. However, follicle transcriptome studies in chickens with timepoints relating to changes in luteinizing hormone level remain unknown. In this study, the largest preovulatory follicle of chicken underwent the early, middle, and terminal stages of ovulatory cycle. Our work provides a comprehensive analysis of lncRNAs and mRNAs in chicken granulosa cells during the ovulatory cycle. A total of 12,479 mRNAs and 7528 lncRNAs were identified among the three stages. Thousands of lncRNAs were annotated, and the most differentially abundant genes were detected in the luteinizing hormone surge stage. Functional features of the lncRNAs and mRNAs at each stage were revealed, which was also associated with the changes in serum luteinizing hormone level. Especially, genes related to oxidative stress, steroids regulation, and inflammatory process were enriched in the luteinizing hormone surge stage, The comprehensive data generated in this study provides the foundation for future investigations to improve the reproductive performance of chickens and explore the mechanisms responsible for female ovarian diseases.

Abstract

Long non-coding RNAs (lncRNAs) and mRNAs are temporally expressed during chicken follicle development. However, follicle transcriptome studies in chickens with timepoints relating to changes in luteinizing hormone (LH) levels are rare. In this study, gene expression in Rohman layers was investigated at three distinct stages of the ovulatory cycle: zeitgeber time 0 (ZT0, 9:00 a.m.), zeitgeber time 12 (ZT12, 9:00 p.m.), and zeitgeber time 20 (ZT20, 5:00 a.m.) representing the early, middle, and LH surge stages, respectively, of the ovulatory cycle. Gene expression profiles were explored during follicle development at ZT0, ZT12, and ZT20 using Ribo-Zero RNA sequencing. The three stages were separated into two major stages, including the pre-LH surge and the LH surge stages. A total of 12,479 mRNAs and 7528 lncRNAs were identified among the three stages, and 4531, 523 differentially expressed genes (DEGs) and 2367, 211 differentially expressed lncRNAs (DELs) were identified in the ZT20 vs. ZT12, and ZT12 vs. ZT0, comparisons. Functional enrichment analysis revealed that genes involved in cell proliferation and metabolism processes (lipid-related) were mainly enriched in the ZT0 and ZT12 stages, respectively, and genes related to oxidative stress, steroids regulation, and inflammatory process were enriched in the ZT20 stage. These findings provide the basis for further investigation of the specific genetic and molecular functions of follicle development in chickens.

Molecular Characterisation, Tissue Distribution, and Expression Profiling of the Cathepsin B Gene during Ovarian Follicle Development in Geese

1. Although there is evidence that Cathepsin B (CTSB) regulates the degradation and absorption of yolk precursors during avian ovarian follicle development, nothing is known about its molecular characteristics, tissue distribution or expression profiles in goose ovarian follicular compartments.2. The intact 1023 bp coding sequence of the goose CTSB gene was obtained for the first time. It encoded a polypeptide of 340 amino acids (AA) containing two conserved functional domains (i.e., Propeptide_C1 and Peptidase_C1A_Cathpsin B) and three active amino acid residues (+108, +279, and +299). Both the nucleotide and AA sequences of goose CTSB gene showed more than 90% similarity with its respective homologs from other avian species.3. The qRT-PCR results showed that CTSB mRNA was ubiquitously expressed in all examined goose tissues, with moderate to high levels in the reproductive organs including the ovarian stroma and oviduct.4. Expression of goose CTSB mRNA in the granulosa layers increased gradually from the 2-4 mm F5 follicles but declined to relatively low levels in the F4-F1 follicles while remaining statistically unchanged in the theca layers throughout follicle development.5. High sequence similarity of goose CTSB gene to other avian species suggested functional conservation of avian CTSB genes, and its fluctuating levels in the granulosa layers may be associated with the orderly progression of goose follicle development. These data laid a foundation for further elucidating the role of CTSB in the avian ovary.

Effects of the FABP4 gene on steroid hormone secretion in goose ovarian granulosa cells

1. To investigate the physiological role of FABP4 in the goose ovary, this study determined the effects of overexpressing and siRNA interfering FABP4 on progesterone (P₄) and oestradiol (E₂) production in granulosa cells. Measurements were made by ELISA, real-time qRT-PCR and western blotting. 2. The concentrations of P₄ and E₂ in the FABP4 overexpression granulosa cells were increased compared to the control group (P > 0.05 for P₄; P < 0.05 for E₂). Likewise, the mRNA and protein expression levels of CYP11A1 and CYP19A1 were significantly higher than in the control group (P < 0.05 or P < 0.001). Conversely, the concentrations of P₄ and E₂ in the FABP4 silencing granulosa cells were significantly decreased compared with the control group (P < 0.001). Likewise, the mRNA and protein expression levels of CYP11A1 and CYP19A1 were significantly lower than in the control group (P < 0.001, or P < 0.01). 3. The study indicated that the FABP4 gene may regulate steroid hormone secretion and the expression of the steroidogenic genes in geese ovarian granulosa cells. These results support the possibility that the FABP4 gene mediates ovarian steroid hormone biosynthesis function and reproduction in geese.