Chapter 2: Function and regulation of porcine selenogenome and selenoproteome

Abstract

Nutritional roles and metabolic impacts of trace element Se are largely mediated by Se-dependent proteins. There are 25 porcine selenoprotein genes identified. These genes are highly conserved and share a close evolutionary relationship with those of humans and rodents. Selenoproteins are widely recognised as ‘antioxidant’ by their verified and(or) presumed functions in free radical scavenging and redox control. Revealing their role and mechanism in regulating glucose homeostasis and energy metabolism signifies a major breakthrough of Se biology. Nearly all porcine selenoprotein genes are responsive to dietary Se deficiency, which is similar to the rodent response pattern. In contrast, expression of porcine selenogenome displays variable responses to moderately high dietary Se intakes, and is more sensitive to high dietary Se intakes than that of rodents. Functional expressions of porcine selenogenome and selenoproteome are also regulated or affected by dietary fat and serine and other factors including heat stress, inflammation, and immunomodulators. Comparatively, more porcine selenoprotein genes (23 vs 15) are responsive to high dietary fat intakes than those of rodents. Dietary serine affects expression of 5 porcine selenoprotein genes. Expression of 60-70% porcine selenoprotein genes in a number of tissues is altered by heat stress and inflammation challenge. Overall, this chapter offers a comprehensive review and critical analysis of dietary Se requirements by pigs, selenoprotein biosynthesis, and evolution, function, and regulation of porcine selenogenome and selenoproteome. Comparative Se biology between pigs and rodents or humans and physiological implications of recent progress are also highlighted.