BackgroundAbdominal fat is the major adipose tissue in chickens. The growth status of abdominal fat during postnatal late development ultimately affects meat yield and quality in chickens. MicroRNAs (miRNAs) are endogenous small noncoding RNAs that regulate gene expression at the post-transcriptional level. Studies have shown that miRNAs play an important role in the biological processes involved in adipose tissue development. However, few studies have investigated miRNA expression profiles and their interaction networks associated with the postnatal late development of abdominal adipose tissue in chickens.ResultsWe constructed four small RNA libraries from abdominal adipose tissue obtained from Chinese domestic Gushi chickens at 6, 14, 22, and 30 weeks. A total of 507 known miRNAs and 53 novel miRNAs were identified based on the four small RNA libraries. Fifty-one significant differentially expressed (SDE) miRNAs were identified from six combinations by comparative analysis, and the expression patterns of these SDE miRNAs were divided into six subclusters by cluster analysis. Gene ontology enrichment analysis showed that the SDE miRNAs were primarily involved in the regulation of fat cell differentiation, regulation of lipid metabolism, regulation of fatty acid metabolism, and unsaturated fatty acid metabolism in the lipid metabolism- or deposition-related biological process categories. In addition, we constructed differentially expressed miRNA–mRNA interaction networks related to abdominal adipose development. The results showed that miRNA families, such as mir-30, mir-34, mir-199, mir-8, and mir-146, may have key roles in lipid metabolism, adipocyte proliferation and differentiation, and cell junctions during abdominal adipose tissue development in chickens.ConclusionsThis study determined the dynamic miRNA transcriptome and characterized the miRNA–mRNA interaction networks in Gushi chicken abdominal adipose tissue for the first time. The results expanded the number of known miRNAs in abdominal adipose tissue and provide novel insights and a valuable resource to elucidate post-transcriptional regulation mechanisms during postnatal late development of abdominal adipose tissue in chicken.

Adiponectin is an important adipocytokine and plays the roles in multiple metabolic processes via binding its receptors - AdipoR1 and AdipoR2, which has also been found to participate in the regulation of the reproductive system of animals, in particular by influencing the secretion of ovarian steroid hormones. To further investigate the expression of adiponectin and its receptors in follicles after in vitro incubation, and their role in the steroid synthesis of laying hens’ ovaries, we performed qRT-PCR and ELISA to detect the expressions of AdipoQ, AdipoR1 , and AidpoR2 , and determined the key genes involved in steroidogenesis and the secretion of estradiol ( E2 ) and progesterone ( P4 ) through the in vitro activation of adiponectin ( AipoRon ) and overexpression or knockdown of AdipoR1 and AdipoR2. Our results revealed that adiponectin and its receptors wildly exist in follicles and granulosa cells, and AdipoRon (5 and 10 µg/mL) had no effect on granulosa cell proliferation and apoptosis but significantly stimulated the secretion of adiponectin and its receptors in granulosa cells after incubation for 24 h. Furthermore, AdipoRon could significantly stimulate the secretion of P4 and inhibit E2 level compared to those of the control group through modulating the key genes expression of steroidogenesis ( CYP19A1, StAR, CYP11A1, FSHR , and LHR ). The secretion of E2 was also decreased in granulosa cells by the treatments of overexpression and knockdown of AdipoR1/2, however, there was no difference in terms of the level of P4 and StAR expression between them if there was overexpression or knockdown of AdipoR1/2. In addition, it was shown that the secretion of E2 only exhibits a marked drop if co-processing 10 µg/mL AdipoRon and pGMLV AdipoR2 compared to single treatments. Taken together, the study highlighted the role of adiponectin and its receptors in the regulation of steroid synthesis and secretion in ovarian granulosa cells in laying hens.

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Background: SIRT1, a NAD+ dependent histone deacetylase, is involved in lipid metabolism, glucose metabolism, apoptosis, and insulin secretion. However, the function of the SIRT1 gene in chickens has not been elucidated. Results: In our study, we identified two novel InDels (c.-1552_-1553insCG and c.-450_-451delCG) in the 5’UTR of the chicken SIRT1 gene. After genotyping 1,141 chickens from 7 breeds, we found that the wild type genotypes for both sites were the most common. An association study using 860 chickens from a Gushi ×Anka F2 resource population showed that c.-1552_-1553insCG was significantly correlated with growth traits and serum lipid indicators. The insertion genotype was most highly associated with body weight in 0-, 2-, and 4-week old chickens, and with shank length and shank circumference in 4-week and 8-week old chickens. The wild type genotype at this site was most highly associated with serum lipid indicators. In contrast, c.-450_-451delCG was significantly correlated with muscle fiber diameter. We also analyzed SIRT1 gene expression in chickens with different InDel genotypes and found that SIRT1 expression in muscle and fat tissue was significantly higher with heterozygous genotypes at both sites, relative to expression in chickens with the corresponding homozygous genotypes. Finally, we analyzed the effects of different haplotypes on SIRT1 promoter activity. The results showed that promoter activity depends on haplotype, with haplotype HapII exhibiting the highest activity. Conclusion: We conclude that the SIRT1 gene is associated with chicken growth traits and that the two InDels influence SIRT1 promoter activity in chickens.