Development of mammary luminal progenitor cells is controlled by the transcription factor STAT5A

Area of Science:

• * Developmental Biology
• * Molecular Biology
• * Endocrinology

Background:

• * Mammary alveologenesis, the formation of milk-producing glands, is essential for lactation.
• * Cytokine signaling pathways, mediated by transcription factors like STAT5A/5B, play critical roles in mammary gland development.
• * The specific roles of STAT5A/5B in mammary stem and progenitor cells remain incompletely understood.

Purpose of the Study:

• * To investigate the role of STAT5A/5B in mammary stem and progenitor cell function.
• * To elucidate the causes of developmental arrest in alveologenesis due to STAT5A/5B deficiency.
• * To determine if STAT5A is sufficient for restoring luminal progenitor populations and alveologenesis.

Main Methods:

• * Analysis of mammary stem and progenitor cell populations in STAT5A/5B-deficient mice.
• * Assessment of mammary duct formation and alveologenesis during pregnancy in vivo.
• * Temporally controlled expression of transgenic STAT5A in STAT5A/5B-deficient mammary epithelium.

Main Results:

• * Loss of STAT5A/5B did not impact mammary stem cell numbers or duct formation.
• * Luminal progenitor cells were significantly reduced in STAT5A/5B-deficient mice, leading to impaired alveologenesis.
• * Reintroduction of STAT5A restored luminal progenitor populations and rescued alveologenesis reversibly.

Conclusions:

• * STAT5A/5B are essential for the differentiation and maintenance of mammary luminal progenitor cells.
• * STAT5A is both necessary and sufficient for the establishment of luminal progenitor cells.
• * STAT5A is a key regulator of mammary alveologenesis, acting through the luminal progenitor compartment.