CircBTBD7 inhibits adipogenesis via the miR-183/SMAD4 axis

Adipogenesis is a complex biological process. However, the regulatory mechanism of circRNAs in adipogenesis is still unclear. In this study, we identified a novel circRNA, circBTBD7, which was highly expressed in adipose tissue and peaked at two days after differentiation in bovine primary adipocytes. When circBTBD7 was knocked down in bovine primary adipocytes, the lipid droplets accumulation was significantly increased. Furthermore, the expression of adipocyte differentiation markers (PPARγ and C/EBPα) and lipogenic genes (FABP4, FASN and ACCα) were significantly upregulated. Moreover, circBTBD7 was mainly located in the cytoplasm, which indicated it was probably to act as competitive endogenous RNAs (ceRNAs). Subsequently, the dual luciferase reporter assay showed that circBTBD7 could bind to miR-183. Further, miR-183 promoted adipogenesis by inhibiting SMAD4. What's more, the rescue assays showed that circBTBD7 attenuated the inhibition of SMAD4 expression by sponging miR-183. In summary, these results suggested that circBTBD7 inhibited adipogenesis via the miR-183/SMAD4 axis.

CEBPβ binding directly to the promoter region drives CEBPɑ transcription and improves FABP4 transcriptional activity in adipose tissue of yak (Bos grunniens)

Fatty acid binding protein 4 (FABP4) was crucial to fatty acid uptake and intracellular transport. However, the mechanisms regulating yak (Bos grunniens) FABP4 transcription were not determined. In the current study, predominant expression levels of yak FABP4 were identified in subcutaneous fat and longissimus dorsi muscles by quantitative real-time polymerase chain reactions (qPCR). The CCAAT/enhancer binding protein alpha (CEBPα) and myocyte enhancer factor 2A (MEF2A), as transcriptional activator or repressor in the promoter region of FABP4, were confirmed by both site-directed mutagenesis experiment and chromatin immunoprecipitation assay. Additionally, molecular mechanisms of CEBPɑ regulation were analyzed to explore the transcriptional regulatory property of FABP4, which indicated that transcriptional activity of CEBPɑ depended on CCAAT/ enhancer binding protein beta (CEBPβ) transcription factor. Our results demonstrated that CEBPβ binding directly to the promoter region drove CEBPɑ transcription, improving yak FABP4 transcriptional activity in adipocytes. This mechanism expanded the information on the transcriptional regulatory network of adipogenesis.

PPARγ regulates fabp4 expression to increase DHA content in golden pompano (Trachinotus ovatus) hepatocytes

N-3 long-chain (≥C20) PUFA (LC-PUFA) are vital fatty acids for fish and humans. As a main source of n-3 LC-PUFA for human consumers, the n-3 LC-PUFA content of farmed fish is important. Previously, we identified fatty acid-binding protein (fabp)-4 as a candidate gene for regulating the n-3 LC-PUFA content. Herein, we further assessed the role of fabp4 in this process. First, a 2059 bp promoter sequence of fabp4 in Trachinotus ovatus was cloned and, using progressive deletion, determined -2006 bp to -1521 bp to be the core promoter sequence. The PPAR-γ binding sites were predicted to occur in this region. A luciferase reporter assay showed that the promoter activity of fabp4 decreased following mutation of the PPARγ binding site and that PPARγ increased the fabp4 promoter activity in a dose-dependent manner, implying that T. ovatus fabp4 is a target of PPARγ. The overexpression of fabp4 or PPARγ increased the DHA content in hepatocytes, whereas suppression of their expression diminished this effect, suggesting that both fabp4 and PPARγ play an active role in regulating DHA content. Moreover, the inhibition of fabp4 attenuated the increase in PPARγ-mediated DHA content, and the overexpression of fabp4 alleviated this effect. Collectively, our findings indicated that fabp4, which is controlled by PPARγ, plays an important role in DHA content regulation. The new regulation axis can be considered a promising novel target for increasing the n-3 LC-PUFA content in T. ovatus.

Zeolite-containing mixture alleviates microbial dysbiosis in dextran sodium sulfate-induced colitis in mice

Inflammatory bowel disease (IBD) is a multifactorial immunomodulatory disorder. In relative nosogenesis, gut microbiota has been the focus of research on IBD. In our previous study, we demonstrated the ameliorating effect of zeolite-containing mixture (Hydryeast®, HY) on dextran sodium sulfate (DSS)-induced colitis, through transcriptomics and proteomics. In the present study, we performed further investigation from the perspective of metagenomics using the gut microbiota. C57BL6 mice were provided an AIN-93G basal diet or a 0.8% HY-containing diet, and sterilized tap water for 11 days. Thereafter, colitis was induced by providing 1.5% (w/v) DSS-containing water for 9 days. DNA was extracted from the cecal contents and pooled into libraries in a single Illumina MiSeq run. The resulting sequences were analyzed using Quantitative Insights Into Microbial Ecology (QIIME) software. According to the alterations in the relative abundance of certain bacteria, and the related gene and protein expressions, HY supplementation could improve the gut microbiota composition, ameliorate the degree of inflammation, inhibit the colonic mucosal microbial growth, and, to some extent, promote energy metabolism in the colon compared with the DSS treatment. Thus, we believe that HY may be a candidate to prevent and treat IBD.

Bovine Stearoyl-CoA Desaturase 1 Promotes Adipogenesis by Activating the PPARγ Receptor

Stearoyl-CoA desaturase 1 (SCD1) is a rate-limiting enzyme that mainly catalyzes the saturated fatty acids (SFAs) into the monounsaturated fatty acids (MUFAs). The expression level of SCD1 is positively correlated with the marbling score. However, the functional mechanism of SCD1 in adipogenesis is still unclear. In this study, we identified SCD1 as highly expressed in subcutaneous and visceral fat, peaking at 2 days after differentiation in bovine stromal vascular fraction (SVF) cells. When the SCD1 was overexpressed in bovine SVF cells, lipid droplets accumulation was increased from 142.46 ± 21.77 to 254.89 ± 11.75 μg/mg (P < 0.01). Further, the expression levels of FABP4, FASN, and ACCα were increased (P < 0.01), while the expression of PPARγ or C/EBPα was not changed at mRNA or protein level (P > 0.05). Dual-luciferase reporter assay showed that the activity of the PPARγ receptor was enhanced by 3.69 times (P < 0.01). Moreover, the contents of palmitoleate (C16:1) and oleate (C18:1) were significantly increased (P < 0.05). Furthermore, 100 μM exogenous oleate increased the lipid accumulation by 22.28 times (P < 0.01). These results suggest that oleate is probably a strong ligand of the PPARγ receptor to enhance adipogenesis.

Single-nucleotide polymorphisms in FABP4 gene associated with growth traits in Egyptian sheep

Aim:

The present study was performed to assess the association of single-nucleotide polymorphisms (SNPs) in the fatty acid-binding protein 4 (FABP4) gene with birth weight (BW), final weight (FW), and average daily gain (ADG) in three Egyptian sheep breeds.

Materials and Methods:

Genomic DNA was extracted from the blood samples of 50 male and female individuals representing Ossimi, Rahmani, and Barki sheep breeds. A 407 bp nucleotide (nt) segment from the first intron of FABP4 was amplified by polymerase chain reaction, sequenced, and analyzed in the different samples.

Results:

Sequence analysis of the determined segment (407 bp) revealed four SNPs (all transition types) at nt position 372 (CP011894.1:g.57605471) A>G, nt position 211 (CP011894.1:g.57605632) A>G, nt position 143 (CP011894.1:g.57605700) T>C, and nt position 111 (CP011894.1:g.57605732) T>C. The allelic and genotypic frequencies for the identified SNPs in the sheep breeds were calculated. At nt positions 372 and 211, two alleles were identified (A and G). Only two genotypes were present at nt position 372 (AA and AG), while three genotypes were present at nt position 211 (AA, AG, and GG). Two alleles (T and C) and three identified genotypes (TT, TC, and CC) were detected at nt positions 143 and 111. Analysis of the results revealed that AA genotype at nt position 372 is associated with higher estimates for BW, FW, and ADG when compared to all the other genotypes. Very high correlation coefficients were found between the genotypes 143-TT and 111-TT and also between 143-TC and 111-TC. The genotypes 372-AG, 211-GG, 211-AA, 143-TT, 143-CC, 111-TT, 111-TC, and 111-CC were associated with negative effects on BW, FW, and ADG.

Conclusion:

The detection of four SNPs in a partial sequence of the Egyptian ovine FABP4 gene intron 1 reflected that this gene harbors substantial diversity. In addition, a novel SNP at nt position 372 (CP011894.1:g.57605471) A>G was associated with higher estimates for BW, FW, and ADG.

Yin Yang 1 Is Essential for Transcriptional Activation of the Bovine Sirt2 Gene in Preadipocytes

Sirtuin 2 (Sirt2) belongs to the NAD⁺-dependent deacetylase family, is more highly expressed than other family members in adipocytes, and plays crucial roles in a wide range of biological processes. However, the mechanisms underlying Sirt2 expression during adipogenesis are poorly studied. In this study, the transcriptional start site (TSS) of Sirt2 was identified and two alternative transcript variants were spliced from Sirt2. The 5'-regulatory region of Sirt2 was also characterized; no TATA-box or CCAAT-box was presented in the 5'-flanking region. Two cytosine-phosphate diester-guanine (CpG) islands were also identified between nucleotides -563 and +4. A dual-luciferase reporter assay revealed that a 178 base pair sequence upstream from the TSS (+1) was the core promoter of Sirt2. Results from a site-directed mutagenesis experiment, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay indicated Yin Yang 1 (YY1) to be a positive regulator of bovine Sirt2 in preadipocytes. YY1 is likely to suppress adipogenesis in two different ways by regulating peroxisome proliferator-activated receptor gamma expression. Our results expand the information on the regulatory network of adipogenesis, which is an important basis for improving beef quality, treating obesity, and other related diseases.

Molecular cloning, characterisation, and expression analysis of adipocyte fatty acid binding protein gene in Xupu goose (Anser cygnoides domesticus)

1. Adipocyte fatty acid binding protein (A-FABP) plays a key role in fatty acid uptake and intracellular transport. The objective of the present study was to identify and characterise the A-FABP gene in Xupu goose.2. The full-length cDNA of goose A-FABP gene was cloned from the liver tissue using reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The distribution of the goose A-FABP in different tissues was determined by quantitative real-time PCR (qRT-PCR).3. The results showed that the full-length cDNA sequence of goose A-FABP was 657 bp, containing a 5'-UTR of 52 bp, a 3'-UTR of 206 bp and an open reading frame (ORF) of 399 bp, which encoded a polypeptide of 132 amino acids (AA).4. The AA sequence of goose A-FABP showed 76.52%, 75.00%, 93.18% and 99.24% identities with previously described homologues from humans (Homo sapiens), mouse (Mus musculus), chicken (Gallus gallus), and duck (Anas platyrhynchos), respectively, and phylogenetic analysis revealed a close relationship among them. The transcript of Xupu goose A-FABP was ubiquitously expressed in all tested tissues, and showed a high-level expression in abdominal fat, sebum and liver.5. A significant positive correlation was identified between A-FABP mRNA abundance in the three adipose tissues and liver weight, ratio of liver to body weight, TG content, and VLDL concentration in the plasma of Xupu goose. A significant negative correlation was observed between the mRNA level of A-FABP and HDL concentration in the plasma of Xupu goose.6. These findings provide a foundation for further research on the function and mechanism of A-FABP in the fat deposition process.

Tissue Expression Analysis and Characterization of Smad3 Promoter in Bovine Myoblasts and Preadipocytes

The transforming growth factor-β (TGFβ) pathway plays many key roles in regulating numerous biological processes. In addition, the effects of TGFβ are mediated by the transcription factor Smad3. However, the regulation of Smad3 activity is not well understood. In the present study, quantitative real-time PCR revealed that the Smad3 gene was expressed ubiquitously in 11 bovine tissues and displayed different expression patterns between muscle and adipose tissue. We further explored the expression and regulation of Smad3 gene by cloning the bovine Smad3 gene promoter; a dual-luciferase reporter assay identified that the core promoter region -337 to -41 bp was located in a CpG island. In addition, mutational analyses and electrophoretic mobility shift assays provided evidence that the KLF6, KLF15, MZF1, and KLF7 binding sites within the Smad3 promoter were responsible for the regulation of Smad3 transcription. These findings were confirmed by executing further RNA interference assays in bovine myoblasts and preadipocytes, which indicated that KLF6, KLF15, MZF1, and KLF7 are important transcriptional activators of Smad3 in both adipose and muscle tissue. These results will provide an important basis for an improved understanding of the TGFβ pathway and new insights in cattle breeding.

Characterization of the promoter region of the bovine SIX1 gene: Roles of MyoD, PAX7, CREB and MyoG

The SIX1 gene belongs to the family of six homeodomain transcription factors (TFs), that regulates the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway and mediate skeletal muscle growth and regeneration. Previous studies have demonstrated that SIX1 is positively correlated with body measurement traits (BMTs). However, the transcriptional regulation of SIX1 remains unclear. In the present study, we determined that bovine SIX1 was highly expressed in the longissimus thoracis. To elucidate the molecular mechanisms involved in bovine SIX1 regulation, 2-kb of the 5' regulatory region were obtained. Sequence analysis identified neither a consensus TATA box nor a CCAAT box in the 5' flanking region of bovine SIX1. However, a CpG island was predicted in the region -235 to +658 relative to the transcriptional start site (TSS). An electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay in combination with serial deletion constructs of the 5' flanking region, site-directed mutation and siRNA interference demonstrated that MyoD, PAX7 and CREB binding occur in region -689/-40 and play important roles in bovine SIX1 transcription. In addition, MyoG drives SIX1 transcription indirectly via the MEF3 motif. Taken together these interactions suggest a key functional role for SIX1 in mediating skeletal muscle growth in cattle.

Molecular Characterization and Transcriptional Regulation Analysis of the Bovine PDHB Gene

The pyruvate dehydrogenase beta subunit (PDHB) is a subunit of pyruvate dehydrogenase (E1), which catalyzes pyruvate into acetyl-CoA and provides a linkage between the tricarboxylic acid cycle (TCA) and the glycolysis pathway. Previous studies demonstrated PDHB to be positively related to the intramuscular fat (IMF) content. However, the transcriptional regulation of PDHB remains unclear. In our present study, the cDNA of bovine PDHB was cloned and the genomic structure was analyzed. The phylogenetic tree showed bovine PDHB to be closely related to goat and sheep, and least related to chicken. Spatial expression pattern analysis revealed the products of bovine PDHB to be widely expressed with the highest level in the fat of testis. To understand the transcriptional regulation of bovine PDHB, 1899 base pairs (bp) of the 5’-regulatory region was cloned. Sequence analysis neither found consensus TATA-box nor CCAAT-box in the 5’-flanking region of bovine PDHB. However, a CpG island was predicted from nucleotides -284 to +117. Serial deletion constructs of the 5’-flanking region, evaluated in dual-luciferase reporter assay, revealed the core promoter to be located 490bp upstream from the transcription initiation site (+1). Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP) in combination with asite-directed mutation experiment indicated both myogenin (MYOG) and the CCAAT/enhancer-binding protein beta (C/EBPß) to be important transcription factors for bovine PDHB in skeletal muscle cells and adipocytes. Our results provide an important basis for further investigation of the bovine PDHB function and regulation in cattle.

Tissue expression analysis, cloning and characterization of the 5'-regulatory region of the bovine FABP3 gene

Fatty acid binding protein 3 (FABP3) is a member of the FABP family which bind fatty acids and have an important role in fatty acid metabolism. A large number of studies have shown that the genetic polymorphisms of FABP3 are positively correlated with intramuscular fat (IMF) content in domestic animals, however, the function and transcriptional characteristics of FABP3 in cattle remain unclear. Real-time PCR analysis revealed that bovine FABP3 was highly expressed in cardiac tissue. The 5'-regulatory region of bovine FABP3 was cloned and its transcription initiation sites were identified. Sequence analysis showed that many transcriptional factor binding sites including TATA-box and CCAAT-box were present on the 5'-flanking region of bovine FABP3, and four CpG islands were found on nucleotides from -891 to +118. Seven serial deletion constructs of the 5'-regulatory region evaluated in dual-luciferase reporter assay indicated that its core promoter was 384 base pairs upstream from the transcription initiation site. The transcriptional factor binding sites RXRα, KLF15, CREB and Sp1 were conserved in the core promoter of cattle, sheep, pigs and dogs. These results provide further understanding of the function and regulation mechanism of bovine FABP3.