Global Gene Expression Profiling and Impact of Cowpea Phenolic Extract (CPE) on Wnt Signalling Genes in Bovine Peripheral Blood

Phenolic-rich forages are beneficial for animal health and nutrition. In this study, the global gene expression profile in cattle whole blood was investigated in response to stimulation with cowpea leaf phenolic extract in vitro. Whole blood from Holstein Friesian cows (n=10) was treated with 10 µg/mL of CPE and untreated samples served as control. Total RNA was isolated, pooled together, reverse transcribed and PCR amplified using gene-specific primers. The Agilent bovine (v2) 4x44K array was used and preliminary gene expression profiles generated using Cy3 labeled cDNA from CPE-stimulated and untreated samples. Fold change in gene expression and pathway analysis was conducted using the GeneSpring GX 13.0 software. A total of 3170 genes were expressed- 1716 up regulated and 1454 down regulated genes respectively. Pathway analysis revealed association with 106 bovine pathways, out of which 66 were significant (p<0.05) including the Wnt signaling pathway. A Real-time quantitative PCR was performed to validate the expression of Wnt signaling genes using the cow Wnt signaling pathway RT-PCR profiler array (Qiagen) with 84 test genes. On the WNT signaling array, 60 genes were expressed- 19 up regulated and 9 downregulated genes respectively. CPE treatment specifically modulated the expression of  the canonical pathway genes which is β-Catenin dependent whiles inhibiting the expression of gene members associated with the planar cell polarity and Wnt /Ca²⁺ signaling pathways. Our study results have implication for the role of diet in maintaining homeostasis and health.