title: Genomic assessment of human cumulus cell marker genes as predictors of oocyte developmental competence: impact of various experimental factors.
abstract: BACKGROUND
  Single embryo transfer (SET) is the most successful way to reduce the frequency of multiple pregnancies following in vitro fertilisation. However, selecting the embryo for SET with the highest chances of pregnancy remains a difficult challenge since morphological and kinetics criteria provide poor prediction of both developmental and implantation ability. Partly through the expression of specific genes, the oocyte-cumulus interaction helps the oocyte to acquire its developmental competence. Our aim was therefore to identify at the level of cumulus cells (CCs) genes related to oocyte developmental competence.
  
  
  RESULTS
  197 individual CCs were collected from 106 patients undergoing an intra-cytoplasmic sperm injection procedure. Gene expression of CCs was studied using microarray according to the nuclear maturity of the oocyte (immature vs. mature oocyte) and to the developmental competence of the oocyte (ability to reach the blastocyst stage after fertilisation). Microarray study was followed by a meta-analysis of the behaviour of these genes in other datasets available in Gene Expression Omnibus which showed the consistency of this list of genes. Finally, 8 genes were selected according to oocyte developmental competence from the 308 differentially expressed genes (p<0.0001) for further validation by quantitative PCR (qPCR). Three of these 8 selected genes were validated as potential biomarkers (PLIN2, RGS2 and ANG). Experimental factors such as inter-patient and qPCR series variability were then assessed using the Generalised Linear Mixed Model procedure, and only the expression level of RGS2 was confirmed to be related to oocyte developmental competence. The link between biomarkers and pregnancy was finally evaluated and level of RGS2 expression was also correlated with clinical pregnancy.
  
  
  CONCLUSIONS
  RGS2, known as a regulator of G protein signalling, was the only gene among our 8 selected candidates biomarkers of oocyte competence to cover many factors of variability, including inter-patient factors and experimental conditions.
authors: INRA, UMR85 Physiologie de la Reproduction et des Comportements, Nouzilly, France.
authors: Prisca
authors: P
authors: Feuerstein
authors: Vincent
authors: V
authors: Puard
authors: Catherine
authors: C
authors: Chevalier
authors: Raluca
authors: R
authors: Teusan
authors: Veronique
authors: V
authors: Cadoret
authors: Fabrice
authors: F
authors: Guerif
authors: Remi
authors: R
authors: Houlgatte
authors: Dominique
authors: D
authors: Royere
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D054885:Cumulus Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D015894:Genome, Human; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis; D020411:Oligonucleotide Array Sequence Analysis; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D000070780:Perilipin-2; D011247:Pregnancy / Q000378:metabolism*; D020710:RGS Proteins / Q000096:biosynthesis*; D012259:Ribonuclease, Pancreatic / Q000096:biosynthesis; D056826:Single Embryo Transfer; D020554:Sperm Injections, Intracytoplasmic
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; C000602982:PLIN2 protein, human; D000070780:Perilipin-2; D020710:RGS Proteins; C087182:RGS2 protein, human; C046366:angiogenin; D012259:Ribonuclease, Pancreatic