During reproduction the mass and number of cells in the uterus and the mammary gland increase rapidly and then diminish more rapidly after their reproductive functions are completed. The diminishment of tissue mass, known as involution, involves an ordered series of events that includes apoptosis of resident cells, neutrophil invasion, the release of degradative enzymes and phagocytosis of cellular debris. Local signals are believed to regulate the progression of involution in each tissue. Here we show that the mammary gland and uterus express high levels of uterocalin, a protein that specifically induces apoptosis in neutrophils and other leucocytes. In the mammary gland, uterocalin expression is induced by weaning. In both tissues, uterocalin is expressed at extremely high levels such that it constitutes an average of 0.2—0.5% of the total extractable protein at its peak. Epithelial cells in the uterus and mammary gland produce uterocalin. In each case, the protein is secreted into the tissue lumen, with mammary-derived uterocalin being found in the milk. The period of highest uterocalin expression invivo is consistent with the hypothesis that one of its physiological roles is to induce apoptosis of infiltrating neutrophils and thereby delay the entry of neutrophils into the tissue. It is proposed that the role of uterocalin during involution is to provide a window of time during which resident cells are protected from the degradative enzymes, free radicals and other secreted products of activated phagocytes to allow these cells to prepare to survive the processes of involution.
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October 2002
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Research Article|
October 01 2002
High expression in involuting reproductive tissues of uterocalin/24p3, a lipocalin and acute phase protein
Joel RYON;
Joel RYON
Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, 3206 Molecular Biology Building, Ames, IA 50011, U.S.A.
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Lee BENDICKSON;
Lee BENDICKSON
Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, 3206 Molecular Biology Building, Ames, IA 50011, U.S.A.
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Marit NILSEN-HAMILTON
Marit NILSEN-HAMILTON
1
Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, 3206 Molecular Biology Building, Ames, IA 50011, U.S.A.
1To whom correspondence should be addressed (e-mail marit@iastate.edu).
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Publisher: Portland Press Ltd
Received:
January 04 2002
Revision Received:
May 03 2002
Accepted:
June 14 2002
Accepted Manuscript online:
June 14 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 367 (1): 271–277.
Article history
Received:
January 04 2002
Revision Received:
May 03 2002
Accepted:
June 14 2002
Accepted Manuscript online:
June 14 2002
Citation
Joel RYON, Lee BENDICKSON, Marit NILSEN-HAMILTON; High expression in involuting reproductive tissues of uterocalin/24p3, a lipocalin and acute phase protein. Biochem J 1 October 2002; 367 (1): 271–277. doi: https://doi.org/10.1042/bj20020026
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