Animal Molecular Breeding, 2024, Vol.14, No.6, 380-387 http://animalscipublisher.com/index.php/amb 381 2 Nutritional Interventions and Gene Expression 2.1 Types of nutritional interventions Nutritional interventions in swine can be broadly categorized into macronutrients, micronutrients, and feed additives. Macronutrients such as proteins and amino acids play a crucial role in gene expression. For instance, dietary lysine, an essential amino acid, has been shown to affect the expression of genes related to muscle protein synthesis in pigs. Micronutrients, including vitamins and minerals, are also significant as they can modulate gene expression through epigenetic mechanisms, such as the regulation of microRNA (miRNA) profiles (Beckett et al., 2014). Feed additives like betaine, a methyl donor, have been used to influence gene expression by altering DNA methylation patterns, impacting pathways such as the STAT3-dependent pathway in piglets (Cai et al., 2015). 2.2 Role of dietary components in regulating gene expression pathways Dietary components regulate gene expression pathways through various mechanisms. Amino acids like lysine can influence transcriptional regulators and pathways involved in protein synthesis and metabolism, such as the inhibition of insulin and activation of STAT3, which affects cell movement and fatty acid metabolism. Betaine supplementation during gestation has been shown to suppress the expression of lipogenic genes in piglets through epigenetic modifications, such as DNA hypermethylation and histone modifications, which are mediated by glucocorticoid receptors (Cai et al., 2016). Additionally, micronutrients can modulate miRNA expression, which in turn regulates gene expression at both transcriptional and post-transcriptional levels. 2.3 Benefits of targeted nutritional strategies for optimizing gene expression in swine Targeted nutritional strategies can optimize gene expression in swine, leading to improved growth, health, and productivity. For example, lysine supplementation can enhance muscle protein synthesis by modulating key transcriptional regulators, thereby improving muscle growth and development (Wang et al., 2019). Maternal betaine supplementation has been shown to reduce hepatic lipogenesis in piglets, potentially leading to healthier metabolic profiles and reduced fat deposition. Furthermore, the modulation of miRNA by dietary components can provide a means to fine-tune gene expression, potentially reducing the risk of diseases associated with dietary imbalances. These strategies highlight the potential of nutritional interventions to enhance swine production through precise regulation of gene expression pathways. 3 Molecular Mechanisms of Nutritional Regulation of Gene Expression 3.1 Epigenetic modifications Epigenetic modifications, such as DNA methylation and histone modifications, play a crucial role in the regulation of gene expression in response to nutritional interventions. Nutrients can influence these epigenetic marks, thereby altering gene expression without changing the underlying DNA sequence. For instance, dietary components like methyl donors (e.g., betaine) can lead to DNA hypermethylation, affecting the expression of lipogenic genes in swine. Additionally, nutrients such as methionine are vital for maintaining the levels of S-adenosylmethionine, a key methyl donor in epigenetic processes, which influences histone methylation and gene expression (Figure 1) (Roy et al., 2020). Other studies highlight the role of dietary polyphenols and flavonoids in modulating DNA methylation and histone acetylation, further demonstrating the impact of nutrition on epigenetic regulation (Abdul et al., 2017). 3.2 Nutrient-sensing pathways Nutrient-sensing pathways, including mTOR and AMPK, are pivotal in mediating the effects of nutritional status on gene expression. These pathways detect the availability of nutrients and modulate metabolic processes accordingly. The mTOR pathway, for example, is activated by amino acids and regulates protein synthesis and cell growth, while AMPK acts as an energy sensor, promoting catabolic pathways when energy is low (Haro et al., 2019). These pathways are integral to maintaining metabolic homeostasis and are influenced by the availability of nutrients, thereby affecting gene expression patterns in swine.
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