The bone morphogenetic protein (BMP) and mitogen-activated protein kinase (MAPK) signaling pathways play an important role in regulation of bone formation and development, however, it remains unclear that the effect of dietary different levels of non-phytate phosphorus (NPP) on these signaling pathways and their correlations with bone phosphorus (P) retention and bone development in broilers. Therefore, this experiment was conducted to investigate the effect of dietary P supplementation on BMP and MAPK signaling pathways and their correlations with bone P retention and bone development in broilers. A total of 800 one-day-old Arbor Acres male broilers were randomly allotted to 1 of 5 treatments with 8 replicates in a completely randomized design. The 5 treatments of dietary NPP levels were 0.15, 0.25, 0.35, 0.45 and 0.55% or 0.15, 0.22, 0.29, 0.36 and 0.43% for broilers from 1 to 21 days of age or 22 to 42 days of age, respectively. The results showed that extracellular signal-regulated kinase 1 (ERK1) mRNA expression in the tibia of broilers on days 14 and 28, phosphorylated-ERK1 (p-ERK1) on day 14, and BMP2 protein expression on days 28 and 42 decreased linearly (P<0.04), while c-Jun N-terminal kinase 1 (JNK1) mRNA expression on day 42 increased linearly (P<0.02) with the increase of dietary NPP level. At 14 days of age, total P accumulation in tibia ash (TPTA), bone mineral concentration (BMC), bone mineral density (BMD), bone breaking strength (BBS) and tibia ash were negatively correlated (r=–0.726 to –0.359, P<0.05) with ERK1 and JNK1 mRNA as well as p-ERK1; tibia alkaline phosphatase (ALP) and bone gal protein (BGP) were positively correlated (r=0.405 to 0.665, P<0.01) with ERK1 mRNA and p-ERK1. At 28 days of age, TPTA, BMC, BMD, BBS and tibia ash were negatively correlated (r=–0.518 to –0.370, P<0.05) with ERK1 mRNA and BMP2 protein, while tibia ALP was positively correlated (r=0.382 to 0.648, P<0.05) with them. The results indicated that TPTA, BMC, BMD, BBS or tibia ash had negative correlations, while tibia ALP and BGP had positive correlations with ERK1 and JNK1 mRNAs, BMP2 protein and p-ERK1, suggesting that bone P retention and bone development might be regulated by BMP and MAPK signaling pathways in broiler chickens.
Obesity presents a serious threat to human health and broiler performance. The expansion of adipose tissue is mainly regulated by the differentiation of preadipocytes. The differentiation of preadipocytes is a complex biological process regulated by a variety of transcription factors and signaling pathways. Previous studies have shown that the transcription factor HMG-box protein 1 (HBP1) can regulate the differentiation of mouse 3T3-L1 preadipocytes by activating the Wnt/β-catenin signaling pathway. However, it is unclear whether HBP1 involved in chicken preadipocyte differentiation and which signaling pathways it regulates. The aim of the current study was to explore the biological function and molecular regulatory mechanism of HBP1 in the differentiation of chicken preadipocytes. The expression patterns of chicken HBP1 in abdominal adipose tissue and during preadipocyte differentiation were analyzed by RT-qPCR and Western blot. The preadipocyte stably overexpressing HBP1 or knockout HBP1 and their control cell line were used to analyze the effect of HBP1 on preadipocyte differentiation by oil red O staining, RT-qPCR and Western blot. Cignal 45-Pathway Reporter Array was used to screen the signal pathways that HBP1 regulates in the differentiation of chicken preadipocytes. Chemical inhibitor and siRNA for signal transducer and activator of transcription 3 (STAT3) were used to analyze the effect of STAT3 on preadipocyte differentiation. The preadipocyte stably overexpressing HBP1 was transfected by the siRNA of STAT3 or treated with a chemical inhibitor of STAT3 for the rescue experiment. The results of gene expression analysis showed that the expression of HBP1 was related to abdominal fat deposition and preadipocyte differentiation in chickens. The results of function gain and loss experiments indicated that overexpression/knockout of HBP1 in chicken preadipocytes could inhibit/promote (P<0.05) lipid droplet deposition and the expression of adipogenesis-related genes. Mechanismlly, HBP1 activates (P<0.05) the signal transducer and activator of transcription 3 (STAT3) signaling pathway by targeting janus kinase 2 (JAK2) transcription. The results of functional rescue experiments indicated that STAT3 signaling mediated the regulation of HBP1 on chicken preadipocyte differentiation. In conclusion, HBP1 inhibits chicken preadipocyte differentiation by activating the STAT3 signaling pathway via directly enhancing JAK2 expression. Our findings provided new insights for further analysis of the molecular genetic basis of chicken adipose tissue growth and development.
Follistatin (FST) is an important regulator of skeletal muscle growth and adipose deposition through its ability to bind to several members of the transforming growth factor-β (TGF-β) superfamily, and thus may be a good candidate for future animal breeding programs. However, the molecular mechanisms underlying the phenotypic changes have yet to be clarified in pig. We generated transgenic (TG) pigs that express human FST specifically in skeletal muscle tissues and characterized the phenotypic changes compared with the same tissues in wild-type pigs. The TG pigs showed increased skeletal muscle growth, decreased adipose deposition, and improved metabolism status (P<0.05). Transcriptome analysis detected important roles of the PIK3–AKT signaling pathway, calcium-mediated signaling pathway, and amino acid metabolism pathway in FST-induced skeletal muscle hypertrophy, and depot-specific oxidative metabolism changes in psoas major muscle. Furthermore, the lipid metabolism-related process was changed in adipose tissue in the TG pigs. Gene set enrichment analysis revealed that genes related to lipid synthesis, lipid catabolism, and lipid storage were down-regulated (P<0.01) in the TG pigs for subcutaneous fat, whereas genes related to lipid catabolism were significantly up-regulated (P<0.05) in the TG pigs for retroperitoneal fat compared with their expression levels in wild-type pigs. In liver, genes related to the TGF-β signaling pathway were over-represented in the TG pigs, which is consistent with the inhibitory role of FST in regulating TGF-β signaling. Together, these results provide new insights into the molecular mechanisms underlying the phenotypic changes in pig.
Fat is an indispensable nutrient and basic metabolite for sustaining life, and milk is particularly rich in fatty acids, including a variety of saturated and unsaturated fatty acids. MicroRNA (miRNA) and mRNA play an important role in the regulation of milk fat metabolism in mammary gland tissue. It has been shown that lipid metabolism has a complex transcriptional regulation, but the mechanism by which milk fat synthesis is regulated through miRNA–mRNA interactions is poorly understood. In this study, we performed transcriptome sequencing with bovine mammary gland tissue in the late lactation (270 and 315 days after parturition) to identify the key gene that regulating milk fat metabolism. A total of 1 207 differentially coexpressed genes were selected, 828 upregulated genes and 379 downregulated genes were identified. The transforming growth factor alpha (TGFA) gene was selected as the target gene, and luciferase reporter assay, Western blotting and qRT-PCR were used for further study. The results demonstrated that miR-140 was an upstream regulator of TGFA, and miR-140 could inhibit (P<0.01) unsaturated fatty acid and triglyceride (TAGs) production in bovine mammary epithelial cells (BMECs). In contrast, TGFA promoted (P<0.01) unsaturated fatty acid and TAG production. Rescue experiments further indicated the miR-140/TGFA regulatory mechanism. Taken together, these results suggest that the miR-140/TGFA pathway can inhibit (P<0.01) milk fat metabolism and improve milk quality by genetic means.
Genome-wide detection for runs of homozygosity analysis in three pig breeds from Chinese Taihu Basin and Landrace pigs by SLAF-seq data
Erhualian (E), Meishan (MS) and Mi (MI) pigs are excellent indigenous pig breeds in Chinese Taihu Basin, which have made great contributions to the genetic improvement of commercial pigs. Investigation of the genetic structure and inbreeding level of the 3 pig breeds is of great significance for the sustainable breeding of commercial pigs. The length and number of runs of homozygosity (ROH) as well as the frequency of genomes covered by ROH can be used as indicators to evaluate the level of inbreeding and the origin of the population. In this study, the ROH characteristics of E, MS, MI and Landrace (L) pigs were analyzed by SLAF-seq data, and the inbreeding coefficient based on ROH (FROH) was calculated. In addition, we have identified candidate genes in the genomic regions associated with ROH. A total of 10 568 ROH were detected in 116 individuals of 4 pig breeds. The analysis showed that there were significant differences in genetic structure between 3 Taihu Basin pig breeds and L, and the genetic structure of E and MI was similar. The results of FROH showed that the inbreeding level of MS was the highest (0.25±0.07), while E and MI were lower than L. Compared with the other 3 pig populations, MS showed a higher frequency of long ROH (>5 Mb), indicating higher inbreeding in MS in recent generations. A large number of candidate genes related to reproductive traits are located in the genomic regions with a high frequency of ROH, and these genes are expected to be used as candidate genes in marker-assisted selection (MAS) breeding programs. Our findings can provide theoretical support for genetic conservation and genetic improvement of 3 pig breeds in Chinese Taihu Basin.
Perilipin1 (PLIN1) is a major phosphorylated protein that specifically coats the surface of neutral lipid droplets (LDs) in adipocytes and plays a crucial role in regulating the accumulation and hydrolysis of triacylglycerol (TG). Mammalian studies have shown that Plin1 gene transcription is mainly regulated by peroxisome proliferator-activated receptor-gamma (PPARγ), the master regulator of adipogenesis. However, the regulatory mechanism of the chicken Plin1 (cPlin1) gene is poorly understood. The present study aimed to investigate whether Plin1 is regulated by PPARγ in chickens and identify its exact molecular mechanism. Reporter gene and expression assays showed that PPARγ2, but not PPARγ1, activated (P<0.01) the cPlin1 gene promoter. An electrophoretic mobility shift assay and mutational analysis revealed that PPARγ2 bound to a special site in the cPlin1 gene promoter to enhance its expression. In summary, our results show that PPARγ promotes the expression of the cPlin1 gene and that PPARγ2 is the main regulatory isoform.
Salmonella is one of the most common food-borne pathogens and its resistance in chicken can be improved through genetic selection. The heterophils/lymphocytes (H/L) ratio in the blood reflects the immune system status of chicken. We compared the genome data and spleen transcriptomes between the H/L ratio-selected and non-selected chickens, after Salmonella infection, aiming to identify the key genes participating in the antibacterial activity in the spleen. The results revealed that, the selected population had stronger (P<0.05) liver resistance to Salmonella typhimurium (ST) than the non-selected population. In the selected and non-selected lines, the identified differentiation genes encode proteins involved in biological processes or metabolic pathways that included the TGF-beta signaling pathway, FoxO signaling pathway, and Salmonella infection pathway. The results of the analysis of all identified differentially expressed genes (DEGs) of spleen revealed that the G protein-coupled receptor (GPCR) and insulin-like growth factor (IGF-I) signaling pathways were involved in the Salmonella infection pathway. Integrated analysis of DEGs and FST (fixation index), identified candidate genes involved in Salmonella infection pathway, such as GPR39, NTRK2, and ANXA1. The extensive genomic changes highlight the polygenic genetic of the immune response in these chicken populations. Numerous genes related to the immune performance are differentially expressed in the selected and non-selected lines and the selected lines has a higher resistance to Salmonella.
Salmonella Enteritidis (SE) is a zoonotic and vertically transmitted pathogen, often colonized in the reproductive tract of adult poultry, which can result in direct contamination of eggs and threaten human health. Previous studies have revealed that some pattern recognition receptors and resistance genes were involved in regulating immune responses to SE invasion in birds. However, the role of these immune response genes was not independent, and the interactions among the genes remained to be further investigated. In this study, SE burden and colonization were determined in reproductive tissue after the ducks were SE-infected, and RNA-sequencing was performed to construct co-expression networks by weighted gene co-expression network analysis (WGCNA). The result showed that SE could be isolated from 22% of infected-birds in any segment of the reproductive tract and the SE was readily colonized in the stroma, small follicle, isthmus, and vagina of the reproductive tracts in morbid ducks. The top central, highly connected genes were subsequently identified three specific modules in the above four tissues at the defined cut-offs (P<0.01), including 60 new candidate regulators and 125 transcription factors. Moreover, those 185 differentially expressed genes (DEGs) in these modules were co-expressed. Moreover, the hub genes (TRAF3, CXCR4 and IL13RA1) were identified to act with many other genes through immune response pathways including NF-kappaB, Toll-like receptor, steroid biosynthesis, and p53 signaling pathways. These data provide references that will understand the immune regulatory relationships during SE infection, but also assist in the breeding of SE-resistant lines through potential biomarkers.
Copyright © Journal of Integrative Agriculture
Sponsored by Chinese Academy of Agricultural Sciences (CAAS)
Co-sponsored by China Association of Agricultural Science Societies (CAASS)
Publishing Service by Elsevier B.V.
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