Skip to main content
ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Quality and Safety Assessment Research Unit » Research » Publications at this Location » Publication #404254
Research Project: Assessment of Quality Attributes of Poultry Products, Grain, Seed, Nuts, and Feed

Location: Quality and Safety Assessment Research Unit

Title: Potential role of ribonucleotide reductase enzyme in mitochondria function and woody breast in broiler chickens

Author
item SHAKERI, MAJID - Oak Ridge Institute For Science And Education (ORISE)
item Kong, Byungwhi
item Zhuang, Hong
item Bowker, Brian

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/7/2023
Publication Date: 7/10/2023
Citation: Shakeri, M., Kong, B.C., Zhuang, H., Bowker, B.C. 2023. Potential role of ribonucleotide reductase enzyme in mitochondria function and woody breast in broiler chickens. Poultry Science Association Meeting Abstract. 102/141.

Interpretive Summary:

Technical Abstract: The cellular events leading to the development of woody breast (WB) myopathy are unclear. Previous work found that affected muscle tissue shows connective tissue accumulation, infiltration of inflammatory cells, and adverse morphological changes in mitochondria. Ribonucleotide reductase (RNR) is the rate-limiting enzyme for de novo synthesis of dNTP, the building block of nuclear and mitochondrial DNA (mtDNA). RNR consists of two subunits encoded by genes RRM1 and RRM2. RRM2 acts as a molecular switch that affects RNR activity and DNA replication. RRM2 mutation is associated with severe reduction in mtDNA leading to impaired energy production in tissues. Additionally, reduced mtDNA has an adverse impact on the levels of mitochondrial gene transcripts resulting in reduced levels of mitochondrial proteins. The objective of this study was to investigate potential RNR differences in WB tissue by examining RRM2 expression and associated pathways. Severe woody breast (WB) and normal breast muscles (N) were obtained from a local processing plant ~3h post-mortem. Several genes and enzyme activities related to RNR including RRM2 were examined. Gene expression was performed by qPCR using SYBR reagents, while enzyme activities were conducted using commercial kits. Data were analyzed using Prism V.9 and t-test. Results showed that WB reduced expression of RRM2 (P=0.01) compared to N. Additionally, WB reduced expression of mtDNA genes required for normal mitochondria function compared to N, including ATP6 (P=0.01), COX1 (P=0.001), CYTB (P=0.03), ND2 (P=0.001) and ND4L (P=0.03). Furthermore, NDUBF7 and COX 14, which are expressed from nuclear DNA and are localized to mitochondria, tended to be reduced for WB compared to N. Lower expression of NDUBF7 and COX14 are related to complex1 deficiency in mitochondria and ATP synthesis, respectively. WB reduced GLUT1 (P=0.05) compared to N which is responsible for glucose transport in cells. By reducing glucose transport to cells, fatty acid oxidation increased for WB versus N as evidenced by increased PDK4 (P=0.0001) and PPARG (P=0.008). WB tended to reduce citric synthase activity and NAD/NADH ratio, while it increased CHRND expression (P=0.001), a possible indicator of high reactive oxygen species levels or elevated sarcoplasmic calcium levels. In conclusion, reduction of RRM2 could be an indicator of mitochondrial dysfunction and impaired ATP synthesis in WB as evidenced by the down-regulation of several genes related to mitochondria leading to impaired energy production and mitochondria dysfunction.