Gene expression in human cumulus cells: one approach to oocyte competence.
BACKGROUND
Dialogue between the oocyte and cumulus cells is essential for oocyte maturation. A prospective laboratory research project was designed to evaluate transcription of specific genes in cumulus cells harvested before intracytoplasmic sperm injection from pre-ovulatory follicles, according to individual oocyte nuclear maturity and developmental competence. Genes were chosen because their expression was induced by the LH peak [Steroidogenic Acute Regulatory protein (STAR), Cyclooxygenase 2 (COX2 or PTGS2), Amphiregulin (AREG)] or because they were involved in oocyte lipidic metabolism [Stearoyl-Coenzyme A Desaturase 1 and 5 (SCD1 and SCD5)] or in gap-junctions [Connexin 43 (CX43 or GJA1)].


METHODS
mRNA levels in cumulus cells were assessed by real-time PCR.


RESULTS
Expression levels of all genes investigated, except Cx43, were increased after resumption of meiosis. Nuclear maturation was thus associated with increased expression of STAR, COX2, AREG, SCD1 and SCD5 by cumulus cells. When considering only cumulus associated with metaphase II oocytes, gene expression was independent of morphological status at Day 2. In contrast, transcript levels were lower and distributed over a narrower range in cumulus enclosing oocytes achieving blastocyst development at Day 5/6 than in cumulus enclosing oocytes unable to develop beyond the embryo stage.


CONCLUSIONS
Further developmental potential from embryo to blastocyst stage was associated with lower expression in a narrow range for these genes.
Feuerstein
P
P
INRA, CNRS, Université de Tours, Haras Nationaux, UMR Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France.
Cadoret
V
V
Dalbies-Tran
R
R
Guerif
F
F
Bidault
R
R
Royere
D
D
D000328:Adult; D066258:Amphiregulin; D002450:Cell Communication / Q000502:physiology*; D018031:Connexin 43 / Q000235:genetics; D054885:Cumulus Cells / Q000166:cytology* / Q000502:physiology*; D051546:Cyclooxygenase 2 / Q000235:genetics; D066255:EGF Family of Proteins; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008540:Meiosis / Q000502:physiology; D009865:Oocytes / Q000166:cytology*; D010750:Phosphoproteins / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020554:Sperm Injections, Intracytoplasmic; D013230:Stearoyl-CoA Desaturase / Q000235:genetics; D014158:Transcription, Genetic; D000098682:Steroidogenic Acute Regulatory Protein
C587848:AREG protein, human; D066258:Amphiregulin; D018031:Connexin 43; D066255:EGF Family of Proteins; C500216:GJA1 protein, human; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D000098682:Steroidogenic Acute Regulatory Protein; C523776:SCD1 protein, human; C502659:SCD5 protein, human; D013230:Stearoyl-CoA Desaturase; D051546:Cyclooxygenase 2