Submitted to: Reproduction, Fertility and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2009
Publication Date: 7/1/2009
Citation: Miles, J.R., Vallet, J.L., Freking, B.A., Nonneman, D.J. 2009. Molecular Cloning and Characterisation of Heparanase mRNA in Porcine Placenta Throughout Gestation. Reproduction, Fertility and Development. 21(6):757-772.
Interpretive Summary: The placenta plays a direct role in regulating fetal growth and survival in the pig. The regulatory function of the pig placenta has implications on uterine capacity, litter size, and postnatal piglet health. As a result, developing an understanding of the mechanisms that regulate placental development and function can provide approaches to improve sow productivity (i.e., number of pigs weaned per sow). The development and modification of the pig placenta is a complex biology, which has not been comprehensively characterized. The objective of the current study was to characterize the expression of heparanase (HPSE) in the pig placenta throughout gestation to assess the potential involvement of HPSE on the development and modification of the pig placenta. This study identified a full-length cDNA sequence that corresponded to a functional HSPE protein in the pig placenta. In addition, the HPSE gene was mapped to a chromosomal location within the pig genome in close proximity to QTLs for litter size and prenatal survival. Furthermore, the expression pattern and localization of HPSE mRNA in the pig placenta throughout gestation illustrated that HPSE likely plays a role in the folding of the fetomaternal interface during early gestation and may play a role in modifying the fetomaternal interface during late gestation. Taken together, these results demonstrate that HPSE likely plays a role in the development and modification of the pig placenta.
Technical Abstract: The placenta contains a complex extracellular matrix composed of several glycosaminoglycans including heparan sulfate (HS). Heparanase (HPSE) is an endoglycosidase that specifically degrades HS. The objective of this study was to clone cDNA encoding porcine HPSE and characterize the expression level and localization of HPSE mRNA in porcine placentas throughout gestation. Placental tissues were collected from the smallest and largest fetuses in litters at d 25, 45, 65, 85, or 105 of gestation (n = 3-5 litters per day). Whole-cell RNA from a placenta of a large fetus at d 105 was reverse transcribed and subjected to PCR with primers designed to amplify the coding region of HPSE. Three transcript variants similar to HPSE were identified in the pig placenta. Real-time PCR and in situ hybridization were used to characterize the expression of two HPSE variants (HPSE v1 and HPSE v2) in placentas between d 25 and 105 of gestation. No significant effect of fetal size was detected by real-time PCR for the expression of HPSE v1 and HPSE v2. However, expression of HPSE v1 and HPSE v2 were elevated (P<0.01) in placentas during very early gestation (d 25) as well as during late gestation (d 85 and 105). Furthermore, expression of HPSE v1 was 22.6 times greater (P<0.001) than HPSE v2 expression, and this relationship was linear (P<0.001). Finally, the mRNA localization of HPSE v1 and HPSE v2 was predominantly associated with the cuboidal trophoblast cells of the folded bilayer located nearest to the maternal endometrium and this was especially apparent during late gestation. These findings indicate that HPSE may be involved in development of the folded bilayer or modifying the fetomaternal interface, especially during late gestation.