title: The expression of prolactin and its cathepsin D-mediated cleavage in the bovine corpus luteum vary with the estrous cycle.
abstract: 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 NH(2)-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-GKPILF~FRLK(Dnp)-D-R-NH(2) 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.
authors.affiliation: Institute of Anatomy, University of Leipzig, Liebigstr 13, 04103, Leipzig, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Erdmann
authors.forename: Albert
authors.initials: A
authors.lastname: Ricken
authors.forename: Claudia
authors.initials: C
authors.lastname: Merkwitz
authors.forename: Ingrid
authors.initials: I
authors.lastname: Struman
authors.forename: Roberta
authors.initials: R
authors.lastname: Castino
authors.forename: Katja
authors.initials: K
authors.lastname: Hummitzsch
authors.forename: Frank
authors.initials: F
authors.lastname: Gaunitz
authors.forename: Ciro
authors.initials: C
authors.lastname: Isidoro
authors.forename: Joseph
authors.initials: J
authors.lastname: Martial
authors.forename: Katharina
authors.initials: K
authors.lastname: Spanel-Borowski
mesh_terms: D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002402:Cathepsin D / Q000378:metabolism*; D002417:Cattle; D003338:Corpus Luteum / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D042783:Endothelial Cells / Q000201:enzymology / Q000502:physiology; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D006107:Granulosa Cells / Q000201:enzymology / Q000502:physiology; D003341:Luteolysis / Q000502:physiology*; D008856:Microscopy, Fluorescence / Q000662:veterinary; D008858:Microscopy, Phase-Contrast / Q000662:veterinary; D009842:Oligopeptides / Q000378:metabolism; D011388:Prolactin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction