title: Smooth muscle α actin is specifically required for the maintenance of lactation.
abstract: Smooth muscle α-actin (Acta2) is one of six highly conserved mammalian actin isoforms that appear to exhibit functional redundancy. Nonetheless, we have postulated a specific functional role for the smooth muscle specific isoform. Here, we show that Acta2 deficient mice have a remarkable mammary phenotype such that dams lacking Acta2 are unable to nurse their offspring effectively. The phenotype was rescued in cross fostering experiments with wild type mice, excluding a developmental defect in Acta2 null pups. The mechanism for the underlying phenotype is due to myoepithelial dysfunction postpartum resulting in precocious involution. Further, we demonstrate a specific defect in myoepithelial cell contractility in Acta2 null mammary glands, despite normal expression of cytoplasmic actins. We conclude that Acta2 specifically mediates myoepithelial cell contraction during lactation and that this actin isoform therefore exhibits functional specificity.
authors: University of Texas Southwestern Medical Center, Dallas, TX 75390-8887, USA.
authors: Nate
authors: N
authors: Weymouth
authors: Zengdun
authors: Z
authors: Shi
authors: Don C
authors: DC
authors: Rockey
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D001835:Body Weight; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005260:Female; D015870:Gene Expression; D015151:Immunoblotting; D007774:Lactation / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D008297:Male; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D008425:Maternal Behavior; D051379:Mice; D057507:Mice, 129 Strain; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D010120:Oxytocics / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology; D011247:Pregnancy; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C558396:Acta2 protein, mouse; D000199:Actins; D010120:Oxytocics; D020033:Protein Isoforms; D010121:Oxytocin