Differential expression of TGF-beta isoforms during postlactational mammary gland involution.
After cessation of lactation, the mammary gland undergoes involution, which is characterized by a massive epithelial cell death and proteolytic degradation of the extracellular matrix. Whereas the expression patterns and also the function of TGF-beta isoforms during mammary gland branching morphogenesis and lactation are well understood, their expression during postlactational involution and therefore a possible role in this process is poorly known. In this study we show that TGF-beta3 expression is dramatically induced (>fivefold) during mouse mammary gland involution when compared to that of virgin mouse, reaching a maximal expression level at day 4 after weaning. In contrast, other TGF-beta isoforms do not display significant increase in expression during involution (TGF-beta1, 1.3-fold and TGF-beta2, <1.5-fold) when compared to that of virgin or lactating mice. During mammary gland involution, TGF-beta3 is expressed in the epithelial layer and particularly in myoepithelial cells. A comparison of the kinetics of TGF-beta3 expression to that of programmed cell death and degradation of the basement membrane suggests that TGF-beta3 functions in the remodeling events of the extracellular matrix during the second stage of involution.
Faure
E
E
Division of Hematology and Oncology, Children's Hospital Los Angeles Research Institute and The Keck School of Medicine of the University of Southern California, CA 90027, USA.
Heisterkamp
N
N
Groffen
J
J
Kaartinen
V
V
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001485:Basement Membrane / Q000166:cytology / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000502:physiology; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000502:physiology*; D051379:Mice; D008808:Mice, Inbred CBA; D012333:RNA, Messenger / Q000032:analysis; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism
D012333:RNA, Messenger; D016212:Transforming Growth Factor beta