Identification of regulatory networks and hub genes controlling mammary gland development and lactation in dairy goats during the late lactation, dry period, and late gestation stages

Abstract

Background From the late lactation to late gestation stages, the mammary gland tissue of goats undergoes a process from involution to remodeling and then to high differentiation of mammary gland tissue. From the perspective of lactation, this is a continuous development process of the goat mammary gland from the termination of lactation to the restoration of lactation. We performed transcriptome sequencing on goat mammary gland tissues at three mammary gland developmental stages to screen for differentially expressed genes that affect mammary gland development and the physiological process of lactation and mapped their expression profiles in three stages. The objective of this study is to reveal the expression characteristics of these genes and their potential function during mammary gland development and lactation. Results We identified 1,381 differentially expressed genes in the mammary gland during three stages and found that the expression level of genes encoding casein, such as alpha-s1-casein (CSN1S1), alpha-s2-casein (CSN1S2), beta-casein (CSN2), and kappa-casein (CSN3), and alpha-lactalbumin (LALBA) were higher in mammary gland tissues during the late lactation stage and late gestation stage than those during the dry period. In addition, we constructed six functional networks related to differentially expressed genes and found that these genes are closely related to mammary gland growth and development, apoptosis, immunity, substance transport, biosynthesis, and metabolism. Finally, we identified 35 differentially expressed transcription factors, which were classified into 16 families, and predicted that transcription factors of the basic leucine zipper domain (bZIP) family and basic helix-loop-helix (bHLH) family regulated the expression levels of genes related to mammary gland development and lactation. Conclusions Among the late lactation, dry period, and late gestation stages, there are differences in the expression levels of genes related to mammary gland growth and development, apoptosis, immunity, basic substance transport, biosynthesis, and metabolism in mammary gland tissues. Some genes in the same family or with similar functions have similar expression patterns. These differentially expressed genes or transcription factors work synergistically to participate in the regulation of mammary gland development and the physiological process of lactation.