The differential transcriptome and ontology profiles of mural and cumulus granulosa cells in stimulated antral follicles

Communication between various ovarian cell types is a prerequisite for folliculogenesis and ovulation. In antral follicles granulosa cells divide into two distinct populations of mural (MGC) and cumulus granulosa cells (CGC), enveloping the antrum and surrounding the oocyte, respectively. IVF offers a good opportunity for analysing their functional properties since granulosa cells can be retrieved during the puncturing procedure of stimulated follicles. The aim of this study was to compare the transcriptomes of MGC and CGC in stimulated antral follicles obtained from 19 women undergoing IVF-ICSI procedure. MGC were obtained from follicular fluid and CGC were acquired after oocyte denudation for micromanipulation. Gene expression analysis was conducted using the genome-wide Affymetrix transcriptome array. The expression profile of the two granulosa cell populations varied significantly. Out of 28 869 analysed transcripts 4 480 were differentially expressed (q-value < 10-4) and 489 showed 2-fold difference in the expression level with 222 genes up-regulated in MGC and 267 in CGC. The transcriptome of MGC showed higher expression of genes involved in immune response, hematological system function and organismal injury, while CGC had genes involved in protein degradation and nervous system function up-regulated. Cell-to-cell signalling and interaction pathways were noted in both cell populations. Furthermore, numerous novel transcripts that have not been previously described in follicular physiology were identified. In conclusion, our results provide a solid basis for future studies in follicular biology that will help to identify molecular markers for oocyte and embryo viability in IVF.

38

Kõks S, Velthut A, Sarapik A, Altmäe S, Reinmaa E, Schalkwyk LC, Fernandes C, Lad HV, Soomets U, Jaakma U, Salumets A