Journal of Agricultural Science; Vol. 8, No. 3; 2016 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 21 Modulation of Bovine Wnt Signaling Pathway Genes by Cowpea Phenolic Extract Sarah Adjei-Fremah 1 , Emmanuel Kwaku Asiamah 1 , Kingsley Ekwemalor 1 , Louis Jackai 2 , Keith Schimmel 1 & Mulumebet Worku 3 1 Department of Energy and Environmental Systems, North Carolina Agricultural and Technical State University, Greensboro, NC, USA 2 Department of Natural Resources and Environmental Design, North Carolina Agricultural and Technical State University, Greensboro, NC, USA 3 Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC, USA Correspondence: Mulumebet Worku, Department of Animal Sciences, North Carolina Agricultural and Technical State University, 1601 E Market St, Greensboro, NC 27411, USA. Tel: 1-336-285-4816. E-mail: worku@ncat.edu Received: December 22, 2015 Accepted: January 29, 2016 Online Published: February 15, 2016 doi:10.5539/jas.v8n3p21 URL: http://dx.doi.org/10.5539/jas.v8n3p21 Abstract The Wingless (Wnt) signaling pathway is a conserved pathway with essential roles in cellular and biological processes in mammals. Wnt signal transduction has been implicated in inflammation, innate immunity and homeostasis via Toll-like receptor and NF-κB pathways. Plant bioactive compounds are capable of modulating the Wnt signalling pathway, which can be either a canonical (β-Catenin dependent) or non-canonical (β-Catenin independent) mechanism. This study evaluated the effect of cowpea phenolic extract (CPE) on the expression and modulation of genes of the Wnt signaling pathway in cow blood. Whole blood collected from six Holstein-Friesian cows was treated with 10 µg/ml of the extract, and evaluated for packed cell volume (PCV), total count and viability of cells, and white blood cell differential count before and after treatment. Cowpea phenolic extract agonist activity in blood was measured using a Bovine toll-like receptor (TLR) 2, and TLR 4 ELISA kit. Total RNA was isolated from the blood cell pellet, reverse transcribed and used for real-time PCR to detect expression of 84 genes on the Cow Wnt signaling pathway array. The total cell-associated β-Catenin level was measured using a commercial ELISA kit. There was no treatment effect on PCV, total cell and viability (P > 0.05). The percentage of mononuclear cells were influenced by treatment, % monocytes (P = 0.0136) decreased and % lymphocytes (P = 0.0114) increased. Treatment with CPE activated cow blood cells, increased TLR2 release and total β-Catenin levels (6 ng/ml, P < 0.05), but TLR4 was not detected. Polyphenols from cowpea modulated the expression of Wnt signalling genes, especially canonical β-Catenin mediated pathway genes. Modulation of Wingless gene expression may be an important mechanism by which polyphenols in cowpea feed impact cellular immune response and homeostasis. Thus, further studies are needed to determine the association of CPE-mediated Wnt gene modulation on blood leucocytes subpopulations and animal health. Keywords: bovine, blood, cowpea, leucocytes, Wnt signaling pathway, Wnt/β-catenin, phenolic compounds 1. Introduction Cowpea (Vigna unguiculata L.Walp) is an important annual legume plant used for food. It is cultivated and consumed largely in Africa, Asia, and South America. Cowpea seed grains are rich in protein: 27% (Gupta et al., 2010). Cowpea with a comparable yield and digestibility to alfafa (Cook, 2005), has high nutritive value, a crude protein of 22%, and are fed to animals as forage, hay or silage (Etana et al., 2013). Using cowpea as protein supplement feed has been recommended for ruminants fed low-quality roughages for improved productivity (Etana et al., 2013; Gwanzura et al., 2012). Cowpea was used as one of the summer legumes for cow and calves on Bermudagrass creep grazing pastures (Pitman et al., 2015). Supplementing small ruminant feed with cowpea forage enhanced feed intake, increased average daily gain, nitrogen intake and digestibility and fecal nitrogen output (Baloyi et al., 2008; Koralagama et al., 2008). Use of cowpea as summer finishing forage in cattle resulted in greater marbling score and increased dressing percentage and consumer steak preference (Schmidt et al., 2013).