From Peptide Masses to Pregnancy Maintenance: A Comprehensive Proteomic Analysis of The Early Equine Embryo Secretome,Blastocoel Fluid,and Capsule |
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| Authors: | Aleona Swegen Christopher G Grupen Zamira Gibb Mark A Baker Marta de Ruijter‐Villani Nathan D Smith Tom A E Stout R John Aitken |
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| Institution: | 1. Priority Research Centre in Reproductive Science, University of Newcastle, Callaghan, NSW, Australia;2. Faculty of Veterinary Science, School of Life and Environmental Sciences, University of Sydney, Camden, NSW, Australia;3. Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands;4. Analytical and Biomolecular Research Facility, University of Newcastle, Callaghan, NSW, Australia |
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| Abstract: | Early pregnancy in the mare is a poorly understood, high risk period during which the embryo communicates its presence to the maternal endometrium. Remarkably, the maternal recognition of pregnancy signal is unknown in the horse. This study aimed to profile the proteins secreted by equine blastocysts into their immediate environment, along with proteins contained in the blastocoel and within the acellular embryo capsule. Embryos were recovered on day 8 after ovulation and cultured for 48 hours. Secretomes of day 9 and day 10 embryos were analyzed by LC‐MS/MS and supported by analysis of blastocoel fluid and embryo capsule. Analyses revealed 72 (24 h) and 97 (48 h) unique protein IDs in the embryo secretome, 732 protein IDs in blastocoel fluid, and 11 proteins IDs in the embryo capsule. Novel findings of interest include secretion of a pregnancy specific proteinase (PAG) by the equine embryo at day 10, along with detection of a prostaglandin receptor inhibiting protein (PTGFRN) and a progesterone potentiating factor (FKBP4) in blastocoel fluid. This is the first comprehensive proteomic analysis of the equine embryo secretome, and provides new insights into the unique physiology of early pregnancy in this species. |
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| Keywords: | Early pregnancy loss Equine embryo Equine reproduction Fertility Secretome |
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