[The cell cycle pathway regulates chicken abdominal fat deposition as revealed by transcriptome sequencing].

With the improvement of growth traits and feed conversion rate, the abdominal fat rate of Chinese local breeds of broilers has been increasing. Excessive abdominal fat deposition not only reduces the slaughter rate and disease resistance of broiler chickens, but also produces waste due to the difficulty of fat treatment. In order to study the regulatory genes and pathways involved in abdominal fat deposition of broilers, we used high-fat diets to feed the Xinghua Chicken, which is a Chinese local breed. Two weeks after feeding, we found that the abdominal fat weight and rate of broilers in the high-fat diet group increased significantly, and the diameter and area of abdominal fat cells also increased significantly. Transcriptome sequencing of abdominal fat and livers showed that the differentially expressed genes in the abdominal fat were mainly enriched in the cell cycle, peroxisome proliferator- activated receptor (PPAR) and extracellular matrix (ECM) receptor signaling pathways. The differentially expressed genes in livers were also significantly enriched in the cell cycle pathway, as well as in the steroid biosynthesis and PPAR signaling pathway. By analyzing the common differentially expressed genes in abdominal fat and liver tissues, we found that these genes were also enriched in cell cycle. Finally, we used the chicken LMH (chicken hepatoma cell) cell line and chicken ICP (immortalized chicken preadipocytes) cell line to do the in vitro validation assays. We used high-fat and common medium to culture the cells. The results showed that after 48 hours, the high-fat medium could significantly promote cell cycle and increase the number of cells in S phase. Additionally, qRT-PCR results showed that the high-fat medium could significantly promote the expression of genes related to cell cycle. In conclusion, we found that high-fat diets activate the cell cycle progression of chicken hepatocytes and preadipocytes, promote cell proliferation, and then increase abdominal fat deposition.

The association of SNPs in Hsp90ß gene 5' flanking region with thermo tolerance traits and tissue mRNA expression in two chicken breeds.

Thermo stress induces heat shock proteins (HSPs) expression and HSP90 family is one of them that has been reported to involve in cellular protection against heat stress. But whether there is any association of genetic variation in the Hsp90ß gene in chicken with thermo tolerance is still unknown. Direct sequencing was used to detect possible SNPs in Hsp90ß gene 5' flanking region in 3 chicken breeds (n = 663). Six mutations, among which 2 SNPs were chosen and genotypes were analyzed with PCR-RFLP method, were found in Hsp90ß gene in these 3 chicken breeds. Association analysis indicated that SNP of C.-141G>A in the 5' flanking region of the Hsp90ß gene in chicken had some effect on thermo tolerance traits, which may be a potential molecular marker of thermo tolerance, and the genotype GG was the thermo tolerance genotype. Hsp90ß gene mRNA expression in different tissues detected by quantitative real-time PCR assay were demonstrated to be tissue dependent, implying that different tissues have distinct sensibilities to thermo stress. Besides, it was shown time specific and varieties differences. The expression of Hsp90ß mRNA in Lingshan chickens in some tissues including heart, liver, brain and spleen were significantly higher or lower than that of White Recessive Rock (WRR). In this study, we presume that these mutations could be used in marker assisted selection for anti-heat stress chickens in our breeding program, and WRR were vulnerable to tropical thermo stress whereas Lingshan chickens were well adapted.

Effect of HSPB9 on Apoptosis of DF-1 Cells.

OBJECTIVE: Our aim was to explore whether heat stress protein (HSP) 9 preferentially expresses under heat stress and affects the expression of other heat stress proteins as well as to explore the effect of HSPB9 overexpression and knockdown on apoptosis in DF-1. METHODS: We used gene cloning to construct an overexpression vector of the target gene, and synthesized the target gene interference fragment to transfect the chicken fibroblast cell line. Gene and protein expression, as well as apoptosis, were detected by RT-qPCR, Western blot, and flow cytometry. RESULTS: Chicken DF-1 cells showed an early state of apoptosis in the early stages of HSPB9 overexpression. In the later stages, as HSPB9 expression increased, the cells showed inhibition of apoptosis. When the cells were under heat stress, HSPB9 expression was much higher and earlier than the expression of HSPB1 and HSPA2. In addition, high expression of HSPB9 had a negative effect on HSPB1 and HSPA2 expression. This negative feedback decreased the percentage of early stages of apoptotic cells and promoted cell survival. CONCLUSION: HSPB9 expression, although rapid, is detrimental to cell survival early during its overexpression. In heat stress, HSPB9 overexpression, while inhibiting the expression of HSPA2 and HSPB1, is beneficial to cell survival.