76 DECIPHERING G-PROTEIN COUPLED RECEPTOR NETWORK DURING BOVINE CONCEPTUS DEVELOPMENT AND MATERNAL RECOGNITION OF PREGNANCY

Abstract

G-protein coupled receptors (GPCR) comprise a large protein family of transmembrane receptors that sense molecules outside the cell to activate the signal transduction pathways inside and, ultimately, the cellular responses. They have a central role in various physiological systems that places them at the forefront of many drug target programs and perturbation in their activity has been cited in many diseases, including infertility (Jean-Alphonse and Hanyaloglu 2011 Mol. Cell. Endocrinol. 331, 205–214). However, little information is available on the types of GPCR and their expression in the bovine conceptus during maternal recognition of pregnancy. The aim of this study was, therefore, to take advantage of the bovine conceptus global gene expression profiles, particularly to examine the expression of various transcripts of GPCR during the window of maternal recognition of pregnancy. Global transcriptome profiling of the bovine conceptuses at 5 key stages of pre- and peri-implantation growth (Day 7, 10, 13, 16 and 19) was carried out using in vivo-derived embryos and state-of-the-art RNA sequencing techniques, following the Illumina standard procedures for library preparation and genome analyzer sequencing (Illumina, San Diego, CA, USA). Following various quality control procedures, the transcripts were mapped to the bovine genome. ANOVA was carried out to detect the differentially regulated transcripts between any 2 developmental stages followed by self-organizing map clustering to identify genes with a similar temporal expression pattern. Those transcripts differentially regulated on Day 16 (the day of maternal recognition of pregnancy in cattle) were screened and submitted to Ingenuity pathway analysis (Ingenuity Systems Inc., Redwood City, CA). Subsequently, the expression profiles of the transcripts in the GPCR network were examined across the 5 key developmental stages. Pathway analysis detected various transcript networks, including the GPCR network, comprising a large number of transcripts (∼30). These include F2RL2, GCGR, VIPR1, LPAR6, RAC2, LPHN3, PTGFR, PTH1R, CNR2, CD97, APLNR and various other GPCR family genes. Analysis of expression profiles across the 5 development stages revealed that these receptors were significantly (P < 0.05) upregulated at Day 16, compared with other time points. The significantly higher expression pattern of these GPCR during this critical stage of pregnancy may suggest an important role during this period of maternal recognition and establishment of pregnancy that contributes to embryo-maternal crosstalk during this critical period. Supported by Science Foundation Ireland (07/SRC/B1156).