title: Calpain 2 activity increases at the time of implantation in rat uterine luminal epithelial cells and administration of calpain inhibitor significantly reduces implantation sites.
abstract: The present study investigated the role of calpain 2 in rat uterine luminal epithelial cells during early pregnancy. Calpain 2 is an intracellular calcium-dependent proteolytic enzyme which cleaves numerous focal adhesion proteins. Calpain 2 was concentrated along the basal cell surface of uterine luminal epithelial cells at the predicted site of focal adhesions on day 1 of pregnancy and remained unchanged at the time of implantation as observed by immunofluorescence microscopy. However, Western blotting analysis showed a marked increase in the active form and a significant decrease in the latent form of calpain 2 at the time of implantation. The increase in calpain 2 activity coincides with the disassembly of focal adhesion proteins, talin, paxillin, integrin β1 and β3 from the site of focal adhesions. Intraperitoneal injection of calpain inhibitor, calpain inhibitor l (ALLN), significantly reduced the number of implantation sites, implying that calpain 2 plays an important role in implantation. The present study suggests a role for calpain 2 in the disassembly of focal adhesions, which has been previously shown to play a key role in uterine receptivity for implantation.
authors.affiliation: School of Medical Sciences (Discipline of Anatomy and Histology) and The Bosch Institute, The University of Sydney, Anderson Stuart Building F13, Sydney, NSW, 2006, Australia, ykan0009@anatomy.usyd.edu.au.
authors.forename: Yui
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Murphy
authors.forename: Margot L
authors.initials: ML
authors.lastname: Day
mesh_terms: D000818:Animals; D002154:Calpain / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D010064:Embryo Implantation / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D022001:Focal Adhesions / Q000378:metabolism; D006023:Glycoproteins / Q000008:administration & dosage / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D051381:Rats; D017208:Rats, Wistar; D013329:Structure-Activity Relationship; D013997:Time Factors; D014599:Uterus / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
chemical_list: D006023:Glycoproteins; C039304:calpain inhibitors; D002154:Calpain; C000594975:Capn2 protein, rat