Source: UNIVERSITY OF GEORGIA submitted to
GENETIC AND FUNCTIONAL GENOMIC APPROACHES TO IMPROVE PRODUCTION AND QUALITY OF PORK
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0217002
Grant No.
(N/A)
Project No.
GEO00658
Proposal No.
(N/A)
Multistate No.
NC-1037
Program Code
(N/A)
Project Start Date
Oct 1, 2007
Project End Date
Sep 30, 2012
Grant Year
(N/A)
Project Director
Rekaya, R.
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
ANIMAL & DAIRY SCIENCE
Non Technical Summary
The current knowledge of factors regulating voluntary feed intake in domestic animals is limited. Although numerous reports have demonstrated that the hypothalamic melanocortin system plays a major role in regulating appetite and energy homeostasis through melanocortin-3 and 4-receptor (MC3R and MC4R), the results are inconsistent and sometimes contradictory. Understanding of the functional role of MC4R on the genetic and metabolic pathways involved in appetite and growth will help enhance the production efficiency in pigs (Objective 1 of the project) through the increase of feed efficiency. To reach that aim, gene expression profiling was used to determine differentially expressed gene after ICV injection of saline or NDP-MSH.
Animal Health Component
40%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3033520108050%
3043520108050%
Knowledge Area
303 - Genetic Improvement of Animals; 304 - Animal Genome;

Subject Of Investigation
3520 - Meat, swine;

Field Of Science
1080 - Genetics;
Goals / Objectives
The objective as outlined in the multistate project are: 1. Further understand the dynamic genetic mechanisms that influence production efficiency and quality of pork. 2. Discover genetic mechanisms controlling animal health in pork production. The expected outputs as outlined in the approved multistate project are: * New information of important genetic variation useful in marker-assisted genetic improvement of US swine herds. This genetic improvement can lead to substantial advances in production efficiency and product quality, including increased litter size, improved growth rate and feed efficiency, improved product quality, and improved resistance to disease. These will result in the availability of pork of high quality at the lowest possible price to the U.S. consumer and for international trade. * Publicly available genomic databases, database systems, and bioinformatics tools, which allow other researchers and industry to capitalize on developed information and methods * New opportunities for alternate uses of swine (e.g. pharmaceuticals, xenotransplantation) through a greater understanding of the biological aspects of swine. These opportunities could create new businesses within the U.S. pork sector and increase profit potential for those participating in this unique industry. * Opportunities to reduce the use of antibiotics in swine production through improved resistance or reduced susceptibility to diseases and a greater understanding of the genetic basis of resistance to disease, allowing for more effective use of antibiotics. This would likely lead to greater consumer acceptance of pork and improve U.S. pork profit potential by increasing the demand for pork and decreasing expenses associated with unhealthy pigs. * Opportunities to enhance pork safety to the consumer through reduced transmission of pathogens. This could lead to greater consumer confidence in U.S. pork products, increased consumer demand for pork, and ultimately improved profitability for U.S. pork producers.
Project Methods
In order to understand the genetic mechanism and the functional role of melanocortin-3and 4-receptor, three MC4R genotypes (2 homozygous and the heterozygous for MC4R) were selected from the UGA swine herd (PIC composite). Thirty six pigs (6 per genotype per treatment) were randomly assigned to one of the following treatments: ICV administration of 150 ul 0.9% saline, or 10 microgram NDP-MSH (agonist) in 150 ul of 0.9% saline. Feed intake was measure at 12 and 24 hours after treatment (time 0). All pigs were sacrificed 24 hours post-injection and hypothalamus, liver and middle layer of back fat was collected and mRNA was hybridized to 24,123 probe set Affymetrix Porcine Genome Arrays. After background adjustment and normalization of the raw expression, a mixed linear model that included the treatment effects, interaction genotype x treatment, the random effect of array and the residual terms was fit to each tissue and gene separately. All contrasts of interest were computed and significant levels after adjustment of multiple comparisons (False discovery rate) were used to identify genes that were differentially expressed. The results showed that MSH suppressed feed intake in all animals at 12 and 24 hr after treatment regardless of genotype (P < 0.04). Futhermore, 5070, 253 and 282 genes, respectively, in adipose, liver and hypothalamic tissue were declared differentially expressed (q<0.07), as a response to central administration of MSH. Additionally, 290 adipose tissue genes, 49 liver genes and 1 hypothalamus gene for the MC4R genotype effect and 1724 adipose genes, 40 liver genes and 2 hypothalamus genes for the genotype x treatment interaction were found to be differentially expressed. Genes representing lipid biosynthesis such as LPL, fatty acid synthase, aconitase-1 and acetyl CoA synthase were down regulated by MSH treatment as were leptin and heat shock protein-70.2 genes.

Progress 10/01/07 to 09/30/12

Outputs
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.

Impacts
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.

Publications

  • 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.