Comparative genome analysis with the human genome reveals chicken genes associated with fatness and body weight

Abstract

The selection of meat-type chickens (broilers) for rapid growth has been accompanied by excessive fat deposition. In this study, we analysed 53 candidate genes that are associated with obesity and obesity-related traits in humans, for which we found chicken orthologues by BLAST searches. We have identified single nucleotide polymorphisms (SNPs) with significant differences in allele frequencies between broilers and layers in each of the following six candidate genes: adrenergic, beta-2-, receptor, surface (ADRB2); melanocortin 5 receptor (MC5R); leptin receptor (LEPR), McKusick-Kaufman syndrome (MKKS), milk fat globule-EGF factor 8 protein (MFGE8) and adenylate kinase 1 (AK1). To examine associations with fatness and/or body weight, we used birds of extreme phenotypes in F(2) and backcross populations with varying levels of abdominal fat weight per cent (%AFW) and body weight. We then assessed the level of gene expression by real-time PCR. In two genes, ADRB2 and MFGE8, we found significant association with %AFW. The ADRB2 gene was found to have a significantly higher expression in the liver of lean chickens compared with those of the fat individuals. We believe that this approach can be applied for the identification of other quantitative genes.

Detecting signatures of selection in nine distinct lines of broiler chickens

“…SNPS in LEPR were previously found to differ in allele frequencies between broilers and layers (Twito et al . ). MXD4 (MAX dimerisation protein 4, Region 27) is a tumour suppressor gene and is involved in cell growth.…”

Mfge8 regulates enterocyte lipid storage by promoting enterocyte triglyceride hydrolase activity

“…Adipose tissue obtained from obese humans has increased expression of Mfge8 and the αv and β5 integrin subunits (36). The gene for MFGE8 is in a region linked with susceptibility to obesity and eating behaviors in humans (37,38). Additionally, circulating Mfge8 concentrations correlate with the degree of hemoglobin glycosylation and are elevated in diabetics, a disease with markedly increased prevalence in obese subjects (39,40).…”

Mfge8 promotes obesity by mediating the uptake of dietary fats and serum fatty acids

“…The MFGE8 gene is located in a region linked with eating behaviors and susceptibility to obesity in humans 18,19 . The expression of MFGE8 and the α v and β 5 integrin subunits are increased in adipose tissue of obese humans 20 .…”