Progress 10/01/07 to 09/30/12
OUTPUTS: Transcriptional profiling in pigs expressing the alternative genotype of MC4R in response to a MC4R agonist: Transcriptional profiling was used to identify genetic mechanisms that respond to alpha-MSH, a MC3/4-R agonist. Three MC4R genotypes were used. Thirty six pigs, 6 per genotype per treatment were assigned to one of the following treatments: ICV administration of 150 ul 0.9% saline, or 10 micro g NDP-MSH in 150 ul of 0.9% saline. Feed intake was measure at 12 and 24 hr. All pigs were sacrificed 24 hours post-injection and hypothalamus, liver and middle layer of back fat was collected. mRNA was hybridized to 24,123 probe set Affymetrix Porcine Genome Arrays. MSH suppressed (P< 0.04) feed intake at 12 and 24 hr regardless of genotype. A mixed linear model was fit to each tissue and gene. The response to central administration of MSH 5070, 253 and 282 genes in adipose, liver and hypothalamic tissue were differentially expressed (q<0.07), respectively. This criterion was satisfied for 290 adipose tissue genes, 49 liver genes and 1 hypothalamus gene for the MC4R genotype effect and 1724 adipose, 40 liver and 2 hypothalamus genes for the genotype x treatment interaction. Genes representing lipid biosynthesis such as LPL, fatty acid synthase, aconitase-1 and acetyl CoA synthase were down regulated. Gene's upregulated in adipose tissue included angiopoietin-like 4, UCP-3 and IGFBP- 3. In the liver, genes representing carbohydrate metabolism; malate dehydrogenase-1, glyceraldehyde-3-phosphate deyhdrogenase and cytochrome-c-oxidase-7 protein-1 were down regulated. In the hypothalamus, solute carrier family1- member 1 (up regulated) and bone morphogenetic protein receptor (down regulated). Interaction of Genotype x Treatment in Adipose Tissue, Liver and Hypothalamus in response to melanocortin-4 receptor agonist: Transcriptional profiling was used to identify genes and pathways that responded to intracerebroventricular (ICV) injection of melanocortin-4 receptor (MC4R) agonist, NDP-MSH, in pigs homozygous for MC4R, D298 allele (n= 12), N298 allele (n = 12)or heterozygous (n = 12). As reported earlier, several genes were differentially expressed due the experimental factors considered in this study. However, it was striking the number of significant interaction of genotype x treatment. Although a small number of animals were used in each combination of experimental factors, every effort was made to balance the design. Several genes showed a clear genotype x treatment interaction in feed intake at 12 and 24 hours after MSH injection, for all three tissues. In fact, 1724, 40 and 2 genotype x treatment interactions were detected for adipose tissue, liver and hypothalamus. In order to further investigate these interactions, especially for adipose tissue, and liver we profiled the expression of some genes with significant interaction using both the normalization PM data and the correspondent LSMEANS. For all 9 selected genes (5 for adipose tissue and 4 for liver) a clear interaction was observed. These results suggest a real genetic control of gene expression sensitivity to MSH treatment which could indicate a difference in genetic background. PARTICIPANTS: Dr. Rick Barb ARS-USDA, Athens Dr. Gary Hausman ARS-USDA, Athens TARGET AUDIENCES: The results of this project provide information especially to other scientists and researchers in the field of feed efficiency in pigs PROJECT MODIFICATIONS: Not relevant to this project.
The transcriptional response to central administration of NDP-MSH in part was similar to a metabolic response to energy deprivation as previously reported in the pig. The large number of significant interactions between MSH treatment and MC4R genotype observed for adipose tissue demonstrates its dynamic and complex role in the regulation of feed intake. We have identified that nesfatin-1 is likely a satiety factor in the pig. Results from gene expression analysis indicate that nesfatin-1 is probably regulated with changes in energy balance, and supports the hypothesis that it is a signal to the central nervous system regarding metabolic state. It is not known at present if nesfatin-1 is a critical metabolic hormone that integrates energy balance with the growth or reproductive axes. Results from combining low and high density SNP panels suggest that for some livestock industries, the proposed procedure could offer a practical and cost effective tool for large scale use of genomic information in the genetic evaluation where animals of high use will be genotyped with the high density SNP panel and the rest of animals (especially females) will be genotyped using the low density panel.
- Lkhagvadory, S., Qu, L., Cai, W., Couture, L., Barb, C.R., Hausman, G.J., Rekaya, R., Nettleton, D., Anderson, L., Dekkers, J., Tuggle, C. 2009. Microarray gene expression profiles of fasting induced changes in liver and adipose tissues of pigs expressing the melanocortin-4 receptor D298N variant. Physiological Genomics. 38(1)98
- Wang Y., R. Rekaya. 2009. A comprehensive analysis of gene expression evolution between humans and mice. Evolutionary bioinformatics online. 5:81-90.
- Lkhagvadorj, S., Qu, L., Cai, W., Couture, Barb, C.R., Hausman, G.J., Nettleton, D., Anderson, L., Deckers, J., Tuggle, C. 2009. Leptin mediates discriminate response to feed restriction in feed efficient pigs. Meeting Abstract.
- Barb, C.R., Hausman, G.J. 2009. Insulin-like growth factor-I feedback regulation of growth hormone and luteinizing hormone secretion in the pig: Evidence for a pituitary site of action. Animal. v.3 (6) p. 844-849.
- Wang, H, R. Rekaya. 2009. Low density SNP chip for non-genotyped animals. J. Anim. Sci. Vol. 87, E-Suppl. 2 p. 125.
- Barb, R., Gary Hausman, Romdhane Rekaya, Clay Lents, Sender Lkhagvadorj, Long Qu, Weiguo Cai, Oliver Couture, Lloyd L. Anderson, Jack Dekkers, and Christopher Tuggle. 2010. Gene expression in hypothalamus, liver and adipose tissues and food intake reponse to melanocortin-4 receptor (MC4R) agonist in pigs expressing MC4R mutations. Physiol Genomics; doi:10.1152/physiolgenomics.00006.2010.