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This Article Full Text Full Text (PDF) All Versions of this Article: 293/5/E1365    most recent 00280.2007v2 00280.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Erdmann, S. Articles by Spanel-Borowski, K. Search for Related Content PubMed PubMed Citation Articles by Erdmann, S. Articles by Spanel-Borowski, K.

The expression of prolactin and its cathepsin D-mediated cleavage in the bovine corpus luteum vary with the estrous cycle

¹Institute of Anatomy and ⁴Institute of Biochemistry, University of Leipzig, Leipzig, Germany; ²Laboratory of Molecular Biology and Genetic Engineering, University of Liege, Liege, Belgium; and ³Department of Medical Sciences, University "Amedeo Avogadro", Novara, Italy

Submitted 3 May 2007 ; accepted in final form 14 August 2007

In the corpus luteum (CL), blood vessels develop, stabilize, and regress. This process depends on the ratio of pro- and antiangiogenic factors, which change during the ovarian cycle. The present study focuses on the possible roles of 23,000 (23K) prolactin (PRL) in the bovine CL and its antiangiogenic NH₂-terminal fragments after extracellular cleavage by cathepsin D (Cath D). PRL RNA and protein were demonstrated in the CL tissue, in luteal endothelial cells, and in steroidogenic cells. Cath D was detected in CL tissue, cell extracts, and corresponding cell supernatants. In the intact CL, 23K PRL levels decreased gradually, whereas Cath D levels concomitantly increased between early and late luteal stages. In vitro, PRL cleavage occurred in the presence of acidified homogenates of CL tissue, cells, and corresponding cell supernatants. Similar fragments were obtained with purified Cath D, and their appearance was inhibited by pepstatin A. The aspartic protease specific substrate MOCAc-GKPILFFRLK(Dnp)-D-R-NH₂ was cleaved by CL cell supernatants, providing further evidence for Cath D activity. The 16,000 PRL inhibited proliferation of luteal endothelial cells accompanied by an increase in cleaved caspase-3. In conclusion, 1) the bovine CL is able to produce PRL and to process it into antiangiogenic fragments by Cath D activity and 2) PRL cleavage might mediate angioregression during luteolysis.

prolactin fragments; lysosomal proteases; acidic microenvironment; extracellular proteolysis; ovary; cow