Detection of Kallikrein Gene Expression and Enzymatic Activity in Porcine Endometrium During the Estrous Cycle and Early Pregnancy1

Abstract

Porcine conceptuses rapidly elongate within the uterine horns prior to the period of placental attachment. During the time of elongation, secretion of estrogen by the developing conceptuses occurs for the establishment of pregnancy through maintenance of corpora lutea and facilitation of placental attachment. Factors associated with the uterine luminal epithelium accentuate embryo attachment by allowing close contact between the conceptus and the uterine epithelium. Kallikrein, a serine protease, may be involved with the timing of conceptus expansion and placental attachment to the uterine surface. The objective of this study was to evaluate kallikrein enzymatic activity, protein, and gene expression in the pig during the estrous cycle and early pregnancy. Enzymatic activity was first detected in uterine flushings (UTF) on Day 12 of the estrous cycle and pregnancy. Activity was enhanced on Day 12 of pregnancy compared to that in cyclic gilts, with a reversal of increased kallikrein activity in cyclic compared to pregnant flushings on Day 15. Western blot analysis with antiserum to human plasma kallikrein detected a 50-kDa product similar to human plasma kallikrein from Day 10 to Day 15 of the estrous cycle and pregnancy. Kallikrein enzymatic activity in UTF was associated with the presence of a 23-kDa reactive product. Gene expression of kallikrein as determined by reverse transcription-polymerase chain reaction indicated the presence of kallikrein mRNA in the porcine endometrium and conceptuses. Results indicate that an increase in uterine luminal kallikrein activity occurs during the estrous cycle at a period that corresponds to rapid conceptus elongation during pregnancy of the pig. The present information suggests that kallikrein may play a role in opening the window for establishment of pregnancy in the pig.

Proteins in the extraembryonic matrix of preimplantation rabbit embryos

“…Kallikrein has been discussed to be one likely candidate (Denker and Fritz 1979). Recently it has been shown that kallikrein is expressed in the endometrium as well as in the embryo during early pregnancy in the pig and mouse (Chan et al 1999;Vonnahme et al 1999). The second major protein of embryonic origin detected in this study is a 50-kDa protein pI 6.0, already detectable at day 5 (Fig.…”

Implantation and Establishment of Pregnancy in the Pig

“…Both IαIH4 protein expression and kallikrein enzymatic activity increase within the uterine environment during the peri-implantation period of pigs (Geisert et al 1998 ;Vonnahme et al 1999 ). The IαIH4 can directly engage the αvβ3 integrin receptor, as well as interact with hyaluronic acid within the ECM to aid in the initial stages of implantation.…”

Integrins and Extracellular Matrix Proteins at the Maternal-Fetal Interface in Domestic Animals

“…Geisert and coworkers [1998] have reported the detection of a 120-kD multi-functional inter-·-trypsin inhibitor heavy chain-like (I·IH4) protein during the mid-luteal phase of the estrous cycle and during the period of Tr attachment to the uterine epithelium. This protein complex may be part of the kallikrein-kininogen-kinin system [Geisert and Yellich, 1997] which serves as a substrate for the plasma serine protease kallikrein; the activity of this enzyme increases in the uterine lumen on Day 12 of pregnancy [Vonnahme et al, 1999]. The I·IH4 has the ability to interact with extracellular matrix component hyaluronic acid and may aid in the ini- tial stages of attachment.…”

“…Prothrombin and thrombin are secreted by the rat uterus [Henrikson et al, 1994]. Rat uterine kallikrein activity is stimulated by estrogen and intralumenal stimulation, and has been implicated in implantation and decidualization [Corthorn and Valdes, 1994;Valdes et al, 1993Valdes et al, , 1996Corthorn et al, 1997], whereas kallikrein activity is present in uterine flushings of cyclic pigs during a period that corresponds to conceptus elongation [Vonnahme et al, 1999]. Likewise, cathepsin-L proteolytic activity and protein has been detected in endometrial GE and uterine flushings from early implanting pigs .…”