Molecular Mechanisms of Lactation in Mammary Gland Systems

The molecular orchestration of lactation involves a finely tuned sequence of developmental and secretory events within the mammary gland. During late gestation, hormonal cues—principally prolactin, glucocorticoids and insulin—activate the JAK–STAT and PI3K–AKT pathways, driving alveolar epithelial cells to differentiate and assemble the cellular machinery required for milk synthesis. Secretory activation is marked by upregulation of genes encoding caseins, whey proteins and lactose‐synthesising enzymes alongside enzymes of de novo fatty acid synthesis and lipid droplet formation. Coordination of lipid biosynthesis relies on transcription factors such as sterol regulatory element–binding protein 1 and peroxisome proliferator–activated receptor γ, which respond to nutrient and hormonal signals to regulate the expression of acetyl‐CoA carboxylase, fatty acid synthase and acyl‐CoA synthetases. Concurrently, extensive remodelling of the endoplasmic reticulum and Golgi apparatus facilitates protein folding, glycosylation and vesicular transport. As lactation proceeds, alveolar homeostasis is maintained by balanced cell proliferation, apoptosis and immune surveillance, ensuring consistent milk output. Involution is initiated by declining milk removal, with altered STAT3 signalling promoting epithelial cell death and stromal remodelling that readies the gland for subsequent reproductive cycles. This integrated network underpins both the nutritional value of milk and its adaptability across species.

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Molecular Mechanisms of Lactation in Mammary Gland Systems publication trend

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Technical terms

Lactogenesis: The process of alveolar differentiation and initiation of milk secretion under hormonal control.

Galactopoiesis: The maintenance phase of lactation during which sustained milk synthesis occurs.

Involution: The regression phase following cessation of milk removal, marked by epithelial apoptosis and tissue remodelling.

Secretome: The complete set of proteins and other molecules secreted by cells into the extracellular space.

Transcriptome profiling: The comprehensive analysis of all RNA transcripts expressed in a cell or tissue at a given time.

References

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3. A cell transcriptomic profile provides insights into adipocytes of porcine mammary gland across development. Journal of Animal Science and Biotechnology (2023).
4. Regulation of Key Genes for Milk Fat Synthesis in Ruminants. Frontiers in Nutrition (2021).