Transcriptome analysis of hen preadipocytes treated with an adipogenic cocktail (DMIOA) with or without 20(S)-hydroxylcholesterol

Identification of genes involved in chicken follicle selection by ONT sequencing on granulosa cells

In chickens, follicle selection is an important process affecting laying traits, which is characterized by the differentiation of granulosa cells and the synthesis of progesterone by granulosa cells from hierarchical follicles. By using Oxford Nanopore Technologies (ONT) approach, we compared the transcriptomes of granulosa cells between pre-hierarchical (Pre-GCs) and hierarchical follicles (Post-GCs) to identify genes underlying chicken follicle selection. A total of 2,436 differentially expressed genes (DEGs), 3,852 differentially expressed transcripts (DETs) and 925 differentially expressed lncRNA transcripts were identified between chicken Pre-GCs and Post-GCs. For all of the significant DETs, the alternative 3'splice sites (A3) accounted for a maximum of 23.74% of all alternative splicing events. Three DETs of the 7-dehydrocholesterol reductase gene (DHCR7) named as T1, T3, and T4, differing in 5'untranslated regions (UTRs), increased in Post-GCs with different folds (T1: 1.83, T3: 2.42, T4: 5.06). The expression of the three DHCR7 transcripts was upregulated by estrogen in a dose-dependent manner, while was downregulated by bone morphogenetic protein 15 (BMP15) and transforming growth factor-beta 1 (TGF-β1). Follicle-stimulating hormone (FSH) and bone morphogenetic protein 4 (BMP4) promoted the expression of the three DHCR7 transcripts in Pre-GCs at lower concentrations, while repressed their expression at higher concentrations. The data from this study may provide a reference for better understanding of the genetic mechanisms underlying follicle selection in chicken and other poultry species.

Effects of physical exercise on muscle metabolism and meat quality characteristics of Mongolian sheep

The objective of this study was to investigate the effects of exercise training on muscle metabolism, fatty acid composition, carcass traits, and meat quality characteristics of Mongolian sheep. Fourteen Mongolian sheep were randomly divided into two groups (7 sheep in each) and placed in two adjacent livestock pens. One group of sheep was kept in the pen (Control [C] group) and the other group of sheep (Training [T] group) were driven away in a field to walk twice a day. The results showed a reduction in pH measured 45 min post mortem, L*, a*, and b* value, intramuscular fat, and carcass length, and an increase in the ultimate pH value and shear force in the meat of T group in comparison with that of C group (p < .050). Also, exercise training moderately affected the fatty acid composition of LT muscle. Compared with C group, the concentrations of myristoleic acid (C14:1) and stearic acid (C18:0) were increased (p < .050), while the concentrations of C20:3 n‐6, neurolic acid (C24:1), and n‐3 polyunsaturated fatty acid (PUFA) were decreased in T group (p < .050). Transcriptome analysis highlighted 621 genes differentially expressed in two groups, including 385 were up‐regulated (e.g., GLUT4 and PGC‐1α) and 236 were down‐regulated (e.g., PLIN1 and ACSL3) in T with respect to C group. Besides, considering these genes, a number of enrichment pathways related to muscle metabolic processes, involving carbohydrate metabolism, lipid metabolism, oxidation reduction process, and muscle tissue development, were highlighted. In conclusion, these results contributed to a better understanding of the possible biological and molecular processes underlying the effects of exercise training on muscle metabolism and meat quality in Mongolian sheep, and provide useful information for contributing to understand the phenotypic and functional differences in meat quality of sheep.

Factors affecting adipose tissue development in chickens: A review

The intense genetic selection for rapid growth in broilers has resulted in an increase in voluntary feed intake and growth rate, accompanied by increased fat deposition in adipose tissue depots throughout the body. Adipose tissue expansion is a result of the formation of adipocytes (several processes collectively referred to as adipogenesis) and cellular accumulation of triacylglycerols inside lipid droplets. In mammals, different anatomical depots are metabolically distinct. The molecular and cellular mechanisms underlying adipose tissue development have been characterized in mammalian models, whereas information in avian species is scarce. The purpose of this review is to describe factors regulating adipogenesis in chickens, with an emphasis on dietary factors and the broiler. Results from many studies have demonstrated effects of dietary nutrient composition on adipose tissue development and lipid metabolism. Transcription factors, such as peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding proteins α and β, and sterol regulatory element binding proteins orchestrate a series of cellular events that lead to an increase in activity of fatty acid transport proteins and enzymes that are responsible for triacylglycerol synthesis. Understanding the mechanisms underlying adipose tissue development may provide a practical strategy to affect body composition of the commercial broiler while providing insights on diets that maximize conversion into muscle rather than fat and affect depot-dependent deposition of lipids. Because of the propensity to overeat and become obese, the broiler chicken also represents an attractive biomedical model for eating disorders and obesity in humans.

Decreased testosterone levels after caponization leads to abdominal fat deposition in chickens

BACKGROUND

Caponization results in reduced androgen levels, which leads to abdominal fat accumulation in capons. In this study, we sought to understand the molecular mechanisms behind this fat accumulation.

RESULTS

Abdominal fat (AF) content increased significantly (P < 0.05) and serum and AF testosterone levels decreased significantly (P < 0.05 or P < 0.01) after caponization. In AF tissue, 90 differentially expressed genes related to lipid metabolism were screened by gene expression profiling in caponized and sham-treated chickens. Among these, six representative genes were significantly up-regulated (APOA1, SCD, FABP7, RXRG, and FADS2) or down-regulated (FABP3) (P < 0.05 or P < 0.01) and were strongly associated with the PPAR pathway. In addition, cell junction pathways were also enriched. In vitro, Fat content was significantly lower in cells treated with testosterone compared with control cells (P < 0.01), and mRNA levels of RXRG, FABP7, and FABP3 changed accordingly, confirming the effect of testosterone on fat deposition.

CONCLUSIONS

The results of this study indicate that testosterone reduction likely regulates gene expression through PPAR and cell junction pathways resulting in increased fat accumulation. These results provide increase our understanding of the biological mechanisms by which caponization induces greater fat accumulation.

Effects of exosomes from LPS-activated macrophages on adipocyte gene expression, differentiation, and insulin-dependent glucose uptake

Obesity is usually associated with low-grade inflammation, which determines the appearance of comorbidities like atherosclerosis and insulin resistance. Infiltrated macrophages in adipose tissue are partly responsible of this inflammatory condition. Numerous studies point to the existence of close intercommunication between macrophages and adipocytes and pay particular attention to the proinflammatory cytokines released by both cell types. However, it has been recently described that in both, circulation and tissue level, there are extracellular vesicles (including microvesicles and exosomes) containing miRNAs, mRNAs, and proteins that can influence the inflammatory response. The objective of the present research is to investigate the effect of exosomes released by lipopolysaccharide (LPS)-activated macrophages on gene expression and cell metabolism of adipocytes, focusing on the differential exosomal miRNA pattern between LPS- and non-activated macrophages. The results show that the exosomes secreted by the macrophages do not influence the preadipocyte-to-adipocyte differentiation process, fat storage, and insulin-mediated glucose uptake in adipocytes. However, exosomes induce changes in adipocyte gene expression depending on their origin (LPS- or non-activated macrophages), including genes such as CXCL5, SOD, TNFAIP3, C3, and CD34. Some of the pathways or metabolic processes upregulated by exosomes from LPS-activated macrophages are related to inflammation (complement activation, regulation of reactive oxygen species, migration and activation of leukocyte, and monocyte chemotaxis), carbohydrate catabolism, and cell activation. miR-530, chr9_22532, and chr16_34840 are more abundant in exosomes from LPS-activated macrophages, whereas miR-127, miR-143, and miR-486 are more abundant in those secreted by non-activated macrophages.

Molecular Fingerprint for Terminal Abdominal Aortic Aneurysm Disease

Background

Clinical decision making in abdominal aortic aneurysms (AAA) relies completely on diameter. At this point, improved decision tools remain an unmet medical need. Our goal was to identify changes at the molecular level specifically leading up to AAA rupture.

Methods and Results

Aortic wall tissue specimens were collected during open elective (eAAA; n=31) or emergency repair of ruptured AAA (rAAA; n=17), and gene expression was investigated using microarrays. Identified candidate genes were validated with quantitative real‐time polymerase chain reaction in an independent sample set (eAAA: n=46; rAAA: n=18). Two gene sets were identified, 1 set containing 5 genes linked to terminal progression, that is, positively associated with progression of larger AAA, and with rupture (HILPDA,ANGPTL4,LOX,SRPX2,FCGBP), and a second set containing 5 genes exclusively upregulated in rAAA (ADAMTS9,STC1,GFPT2,GAL3ST4,CCL4L1). Genes in both sets essentially associated with processes related to impaired tissue remodeling, such as angiogenesis and adipogenesis. In gene expression experiments we were able to show that upregulated gene expression for identified candidate genes is unique for AAA. Functionally, the selected upregulated factors converge at processes coordinated by the canonical HIF‐1α signaling pathway and are highly expressed in fibroblasts but not inflammatory cells of the aneurysmatic wall. Histological quantification of angiogenesis and exploration of the HIF‐1α network in rAAA versus eAAA shows enhanced microvessel density but also clear activation of the HIF‐1α network in rAAA.

Conclusions

Our study shows a specific molecular fingerprint for terminal AAA disease. These changes appear to converge at activation of HIF‐1α signaling in mesenchymal cells. Aspects of this cascade might represent targets for rupture risk assessment.

Lipid Metabolism is Closely Associated with Normal Testicular Growth Based on Global Transcriptome Profiles in Normal and Underdeveloped Testis of Obese Zucker (fa/fa) Rats

Zucker (fa/fa) obese rats often have non-identical and differently sized paired testes, leaving one testis underdeveloped. Our earlier study found that the underdeveloped testes, > 30% smaller than the normal ones, have a selective decrease in docosapentaenoic acid (22:5n-6), a dominant fatty acid in the testes. This study was conducted to examine global testicular transcriptome profile in underdeveloped testes relative to developed ones using Rat Gene 2.0 ST Array (Affymetrix, USA). Testes were obtained from 14-week-old, sexually mature male obese (fa/fa) Zucker rats. Out of the 1790 transcripts differentially expressed, 1108 and 682 were over-expressed in the underdeveloped and normal testis, respectively (fold change ≥ 2 and P < 0.05). The ingenuity pathway analysis indicated that transcripts that were under-expressed in the underdeveloped testis, relative to the normal testes, are involved in triacylglycerol biosynthesis, sphingomyelin metabolism and phosphatidylglycerol biosynthesis. Transcripts that were over-expressed in underdeveloped testes, relative to normal testis, are involved in the production of nitric oxide and reactive oxygen species, and nuclear factor (erythroid-derived 2)-like 2 mediated oxidative stress responses. These data indicate that genes involved in lipid metabolism and oxidative stress play a crucial role in testicular growth and the maintenance of testical health.

Fatty Acids Have Different Adipogenic Differentiation Potentials in Stromal Vascular Cells Isolated from Abdominal Fat in Laying Hens

This study was conducted to examine the effects of fatty acids (FA) with/without chicken serum (CS) on the expression of adipogenic transcripts and adipogenesis in chicken stromal vascular cells (SVC). In experiment 1, SVC were grown in DMEM containing 10% FBS (Control) and treated with 300 µM oleic acid (OLA) + FBS, linoleic acid (LNA) + FBS, palmitic acid (PAM) + FBS, or stearic acid (STA) + FBS for 48 h. In experiment 2, cells were grown in DMEM containing 5% CS and treated with 300 µM OLA (CS + OLA), PAM (CS + PAM), STA (CS + STA) or 200 µM LNA (CS + LNA) for 48 h. Adipogenesis was determined using Oil Red O staining and glycerol-3-phosphate dehydrogenase (GPDH) activity. The proportion of OLA, PAM, or STA was increased (P < 0.05) in SVC grown in either FBS or CS with OLA, PAM or STA. Adipogenesis was induced in FBS + OLA, FBS + LNA, FBS + PAM, FBS + STA, CS + OLA, CS + LNA, CS + PAM, or CS + SAT compared to FBS. GPDH activity was significantly higher in FBS + OLA and FBS + LNA than one in FBS. Compared to FBS, the expression of FABP4 mRNA increased (P < 0.05) in FBS + OLA, FBS + LNA, or FBS + PAM, whereas that of C/EBPα, C/EBPβ, and ATGL increased (P < 0.05) in FBS + OLA or FBS + LNA cells. Expression of FABP4 and C/EBPβ mRNA was higher in CS, CS + OLA, CS + LNA, CS + PAM, or CS + SAT compared with (FBS, whereas the expression of ATGL and C/EBPα was higher in CS, CS + OLA, or CS + LNA than FBS cells. In conclusion, these results showed that FA have different potentials to induce adipogenesis, LNA is the most potent among the tested FA, and these potentials can be improved in the presence of CS.

Genome-Wide Analysis of lncRNA and mRNA Expression During Differentiation of Abdominal Preadipocytes in the Chicken

Long noncoding RNAs (lncRNAs) regulate adipogenesis and other processes associated with metabolic tissue development and function. However, little is known about the function and profile of lncRNAs during preadipocyte differentiation in the chicken (Gallus gallus). Herein, lncRNA and mRNA expression in preadipocytes at different stages of differentiation were analyzed using RNA sequencing. A total of 1,300,074,528 clean reads and 27,023 novel lncRNAs were obtained from 12 samples. The number of genes (1336 lncRNAs and 1759 mRNAs; 3095 in total) differentially expressed across various stages declined as differentiation progressed. Differentially expressed genes were found to be involved in several pathways related to preadipocyte differentiation that have been extensively studied, including glycerolipid metabolism, and the mammalian target of rapamycin, peroxisome proliferator-activated receptor, and mitogen-activated protein kinase signaling pathways. To our knowledge, some pathways are being reported for the first time, including the propanoate metabolism, fatty acid metabolism, and oxidative phosphorylation pathways. Furthermore, 3095 differentially expressed genes were clustered into eight clusters, and their expression patterns were determined through K-means clustering. Genes involved in the K2 cluster likely play important roles in preadipocyte differentiation. Six stage-specific modules related to A0 (day 0), A2 (day 2), and A6 (day 6) stages were identified, using weighted coexpression network analysis. Nine central, highly connected .genes in stage-specific modules were subsequently identified, including XLOC_068731, XLOC_022661, XLOC_045161, XLOC_070302, CHD6, LLGL1, NEURL1B, KLHL38, and ACTR6. This study provides a valuable resource for further study of chicken lncRNA and facilitates a better understanding of preadipocyte differentiation in the chicken

Phenamil enhances the adipogenic differentiation of hen preadipocytes

A study was conducted to examine the effect of phenamil on adipogenic differentiation and expression of key adipogenic transcripts in hen preadipocytes. Preadipocytes were isolated from 20-week old Single Comb White Leghorn hens (Gallas gallus, Lohman strain). The experiment lasted for 48 h and had six treatments. Non-treated control (C) cells, cells treated with dexamethasone, 3-isobutyl-1-methylxanthine, insulin, and oleic acid (DMIOA) (T1), DMIOA + 15 μM phenamil (T2), DMIOA + 30 μM phenamil (T3), 15 μM phenamil alone (T4), and 30 μM phenamil alone (T5). Neutral lipid accumulation and the mRNA expression of key adipogenic transcripts were measured in all treatments and compared. Lipid accumulation was detected in T1, T2, and T3 only. Expression of peroxisome proliferator receptor-activator gamma 2 (PPARγ2), the core enhancer binding protein α (C/EBPα), C/EBPβ, fatty acid binding protein 4 (FABP4), and lipoprotein lipase (LPL) as well as ETS variant 4 (ETV4) and 5 was higher (P < 0.05) in T2, T3, T4, and T5 compared to C. Expression of these transcripts was higher (P < 0.05) in T2 and T3 compared to T4 and T5. The core enhancer binding protein α, C/EBPβ, and FABP4 were highly expressed (P < 0.05) in T1 compared to C. However, the expression of PPARγ2, LPL, and ETV4 and ETV5 was not significantly different. Expression of C/EBPα, C/EBPβ, and FABP4 was higher (P < 0.05) in T2 and T3 compared to T1. Expression of sterol regulatory element binding protein 1 (SREBP1) and leptin receptor (LEPR) was not significantly different among the treatments. In conclusion, phenamil enhances DMIOA-induced adipogenic differentiation of hen preadipocytes but does not induce adipogenesis by itself.