New Insights on Vitamin K Metabolism in Senegalese sole () Based on Ontogenetic and Tissue-Specific Vitamin K Epoxide Reductase Molecular Data.

Vitamin K (VK) is a key nutrient for several biological processes (e.g., blood clotting and bone metabolism). To fulfill VK nutritional requirements, VK action as an activator of pregnane X receptor (Pxr) signaling pathway, and as a co-factor of γ-glutamyl carboxylase enzyme, should be considered. In this regard, VK recycling through vitamin K epoxide reductases (Vkors) is essential and should be better understood. Here, the expression patterns of () and () were determined during the larval ontogeny of Senegalese sole (), and in early juveniles cultured under different physiological conditions. Full-length transcripts for and were determined and peptide sequences were found to be evolutionarily conserved. During larval development, expression of showed a slight increase during absence or low feed intake. Expression of continuously decreased until 24 h post-fertilization, and remained constant afterwards. Both were ubiquitously expressed in adult tissues, and highest expression was found in liver for , and ovary and brain for . Expression of and was differentially regulated under physiological conditions related to fasting and re-feeding, but also under VK dietary supplementation and induced deficiency. The present work provides new and basic molecular clues evidencing how VK metabolism in marine fish is sensitive to nutritional and environmental conditions.