Expression of hypoxia-inducible factors during bovine preimplantation embryo development / Alexandra Harvey.
Year: 2003
Type: dissertation
Abstract: The oxygen environment within the reproductive tract is considerably lower than that commonly used for in vitro culture, exhibiting a decrease from the oviduct to the uterus, suggesting that an oxygen gradient exists ln vivo as a stimulus for embryo development.Hypoxia-inducible factors (HIFs) are transcription factors whose expression is regulated by the cellular oxygen tension' The aims of the present study were to characterise the mRNA expression pattern of HIF subunits HIFlcr and HIFIp and determine the response of HIFcr subunits (at the mRNA and protein level), as well as the oxygen-regulated genes GLUTI and VEGF, to alterations in post-compaction oxygen and redox state.Both HIFIc¿ and HIF1B mRNA was detected throughout preimplantation embryo development' HIFIg protein remained undetected at any stage of embryo development, as well as following the addition of the hypoxia mimic desferrioxamine (DFO), However, HIFlcr protein was observed in oocytes following anoxic culture.HIF2c¿ protein was localised to the nucleus at the 8-16 cell and blastocyst stages.In addition, both HIFcr proteins were detected in cumulus cells.Following post- compaction culture at 2,7 or 20Yo oxygen to the blastocyst stage GLUTI mRNA expression was significantly increased under 2Yo oxygen, as well as following DFO treatment.VEGF mRNA was unaltered by any treatment applied.HIFIo and HIF2ct mRNA was unaltered by oxygen, as has been reported for somatic cells, however redox regulation of both subunits was observed in response to the oxidative phosphorylation uncoupler 2, -dinitrophenol (DI'IP) post-compaction.Furthermore, alterations in HIF2o protein localisation were evident, particularly within the inner cell mass (ICM), in response to all treatments, whereby 20% oxygen significantly decreased HIF2cr localisation within the ICM and increased cytoplasmic localisation, while 2olo oxygen, DNP and DFO increased ICM nuclear localisation.Moreover blastocyst quality was improved following culture under 2o/o oxygen, or in the presence of DNP or DFO post-compaction' ii lv V vi vii viii xl1 xvii Chapter 1. Review of the Literature 1 culture in the presence or absence of DFO 5.3 Number of total, ICM and TE cells (mean + S.E.M) of Day 7 expanded and hatched blastocysts following culture in the presence of absence of DNP or DFO Page 11 56
Author: Alexandra J. Harvey
Language: English
Subfield: Reproductive Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2694468954