Differential Expression of Cell Cycle Regulators During Hyperplastic and Hypertrophic Growth of Broiler Subcutaneous Adipose Tissue

Abstract

Hyperplastic growth and hypertrophic growth within adipose tissue is tightly associated with cell cycle activity. In this study, CCNG2 and CDKN2C were found to be correlated with cell cycle inhibition during fat cell differentiation, whereas CCND3, CCNA1, and ANAPC5 were positively associated with cell cycle activity during fat cell proliferation after selection based on GEO datasets available on the NCBI website. The findings were validated through comparison of expressions of these genes among different tissues/fractions in broiler chickens and time points during primary cell culture using quantitative real-time PCR. Development of broiler subcutaneous adipose tissue was investigated on embryonic days 15 and 17 and on post-hatch days 0, 5, 11, and 33 using H&E staining and PCNA immunostaining with DAPI counter stain. In addition, mRNA expressions of five cell cycle regulators as well as precursor cell and adipocyte markers were measured at those time points. The results suggest that cellular proliferation activity decreased as the fat pad grows, but a population of precursor cells seemed to be maintained until post-hatch day 5 despite increasing differentiation activity. Hypertrophic growth gradually intensified despite a slight cessation on post-hatch day 0 due to increased energy expenditure during hatching and delayed food access. From post-hatch day 5 to day 11, most of the precursor cells may become differentiated. After post-hatch day 11, hyperplastic growth seemed to slow, while hypertrophic growth may become dominant. This study provides further understanding about broiler fat tissue development which is imperative for effective control of fat deposition.

Difference in developmental dynamics between subcutaneous and abdominal adipose tissues in goose (Anser Cygnoides)

“…During the past 20 yr, adipose tissue has become the subject of intensive research, which has been recognized as an important endocrine organ involved mainly in the control of weight regulation in mammals and poultry ( Cannon and Nedergaard, 2004 ; Wronska and Kmiec, 2012 ). Understanding development of adipose tissue is crucial for curing obesity in humans and controlling fat deposition in meat-producing animals to yield higher quality meat with improved feed efficiency ( Zhang et al, 2015 ). Unlike other organs, adipose tissue is compartmentalized into discrete depots distributed throughout the body as subcutaneous, abdominal, intermuscular (between the muscles), or intramuscular (within the muscle) fat in chickens and some other avian species.…”

­­­­­­Genomic analysis of worldwide sheep breeds reveals PDGFD as a major target of fat-tail selection in sheep

“…In addition to PDGFD, several other selected genes identi ed in this study have known functions that are associated with lipid metabolism, such as ENPP2 [14], ANAPC5 [15], RNF34 [16], KDM2B [17], CAMKK2 [18], TSHR [19], and CDH1 [20]. The genetic differentiation for these genes was not as pronounced as for the PDGFD loci, implying that these loci likely contribute to the phenotypic difference with relatively small effects.…”

­­­­­­Genomic analysis of worldwide sheep breeds reveals PDGFD as a major target of fat-tail selection in sheep

“…In addition to PDGFD, several other selected genes identi ed in this study have known functions that are associated with lipid metabolism, such as ENPP2 [15], ANAPC5 [16], RNF34 [17], KDM2B [18], CAMKK2 [19], TSHR [20], and CDH1 [21]. The genetic differentiation for these genes was not as pronounced as for the PDGFD loci, implying that these loci likely contribute to the phenotypic difference with relatively small effects.…”