Expression of insulin-like growth factor (IGF), IGF receptor, and IGF-binding protein messenger ribonucleic acids in luteinized granulosa cells from different size follicles after controlled ovarian hyperstimulation

Human granulosa cells: insulin and insulin-like growth factor-1 receptors and aromatase expression modulation by metformin

BACKGROUND/AIM

Granulosa cells are the source of the most important ovarian steroids. Even in patients without significant improvement in metabolic parameters, metformin has apparently an important effect on the ovary. The aim of this study was to evaluate gene and protein expression of an insulin receptor (IR), insulin-like growth factor-1 (IGF1) receptor (IGF1R) and aromatase in granulosa cells treated with metformin and insulin.

METHODS

Luteinized granulosa cells were collected from 27 patients during in vitro fertilization procedures. Cells were isolated, stored in culture for 24 h and divided into four groups: control; metformin for 30 min, and metformin for 30 min plus insulin for 30 or 60 min.

RESULTS

IR and IGF1R mRNA expression was significantly enhanced by metformin but was not affected by insulin. Aromatase mRNA expression was significantly reduced in metformin-incubated cells following stimulation with insulin for 30 min. No statistical differences were found in IGF1R and aromatase protein expression, and IR expression was not detected.

CONCLUSION

A direct effect of metformin on the gene expression of IGF1R, IR and aromatase was observed. Further studies should investigate the role of IGF1R, IR and aromatase in ovarian physiology for a better understanding of the effect of metformin.

mRNA expression pattern of insulin-like growth factor components of granulosa cells and cumulus cells in women with and without polycystic ovary syndrome according to oocyte maturity

The mRNA expression of insulin-like growth factor (IGF) components was investigated in granulosa cells (GCs) and cumulus cells (CCs) sampled from immature and mature follicles in women with and without polycystic ovary syndrome (PCOS). Gene expression for IGF-binding protein (IGFBP) 3 in GCs definitely differed between normal women and women with PCOS, whereas increase in IGF-I and IGF receptor (IGFR) 2 mRNA in mature-follicle GCs, increase in IGF-II, IGFR-1, and IGFBP-4 mRNA in immature-follicle GCs, increase in IGFR-2 and IGFBP-2 mRNA in mature-follicle CCs, and increase IGFBP-6 mRNA in immature-follicle CCs were observed in both normal women and women with PCOS.

Differential gene expression in human granulosa cells from recombinant FSH versus human menopausal gonadotropin ovarian stimulation protocols

BACKGROUND

The study was designed to test the hypothesis that granulosa cell (GC) gene expression response differs between recombinant FSH and human menopausal gonadotropin (hMG) stimulation regimens.

METHODS

Females < 35 years-old undergoing IVF for tubal or male factor infertility were prospectively randomized to one of two stimulation protocols, GnRH agonist long protocol plus individualized dosages of (1) recombinant (r)FSH (Gonal-F) or (2) purified human menopausal gonadotropin (hMG; Menopur). Oocytes were retrieved 35 h post-hCG, and GC were collected. Total RNA was extracted from each GC sample, biotinylated cRNA was synthesized, and each sample was run on Human Genome Bioarrays (Applied Microarrays). Unnamed genes and genes with <2-fold difference in expression were excluded.

RESULTS

After exclusions, 1736 genes exhibited differential expression between groups. Over 400 were categorized as signal transduction genes, approximately 180 as transcriptional regulators, and approximately 175 as enzymes/metabolic genes. Expression of selected genes was confirmed by RT-PCR. Differentially expressed genes included A kinase anchor protein 11 (AKAP11), bone morphogenetic protein receptor II (BMPR2), epidermal growth factor (EGF), insulin-like growth factor binding protein (IGFBP)-4, IGFBP-5, and hypoxia-inducible factor (HIF)-1 alpha.

CONCLUSIONS

Results suggest that major differences exist in the mechanism by which pure FSH alone versus FSH/LH regulate gene expression in preovulatory GC that could impact oocyte maturity and developmental competence.

Expression of the insulin-like growth factor and insulin systems in the luteinizing macaque ovarian follicle

OBJECTIVE

To determine intrafollicular hormone levels and characterize the mRNA expression of the insulin-like growth factor (IGF) receptors, IGF binding proteins (IGFBP), and pregnancy-associated plasma protein-A (PAPP-A) in granulosa cells before and after an ovulatory hCG stimulus.

DESIGN

Experimental animal study.

SETTING

Academic medical center.

ANIMAL(S)

Adult rhesus macaques.

INTERVENTION(S)

Animals received exogenous FSH to promote the development of multiple preovulatory follicles. Follicles were aspirated before (0 hours) or 3, 6, 12, or 24 hours after an ovulatory hCG bolus.

MAIN OUTCOME MEASURE(S)

IGF1, IGF2, and insulin levels in follicular fluid were determined by radioimmunoassay. Messenger RNA (mRNA) levels in granulosa cells were determined by real-time reverse transcriptase-polymerase chain reaction. IGFBPs and PAPP-A in follicular fluid were determined by Western blot analysis and enzyme-linked immunosorbent assay.

RESULT(S)

IGF1, IGF2, and insulin in follicular fluid did not change during luteinization. IGF1R, IGFBP1, and IGFBP2 mRNAs were unchanged by hCG. IGF2R, IGFBP3, -5, and -6 and PAPP-A mRNA levels increased after hCG administration, while insulin receptor and IGFBP4 mRNA levels decreased after hCG administration. IGFBP3 and -6 and PAPP-A protein increased after hCG administration.

CONCLUSION(S)

Dynamic changes in the expression of the IGFBPs and PAPP-A suggest tight regulation of IGF action during ovulation and corpus luteum formation.

Significance of mRNA levels of connexin37, connexin43, and connexin45 in luteinized granulosa cells of controlled hyperstimulated follicles

OBJECTIVE

To evaluate the mRNA levels of connexins in different sizes of luteinized follicles.

DESIGN

Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) to determine the connexin mRNA levels in the granulosa cells of 91 luteinized follicles.

SETTING

Academic tertiary care medical center and research unit of university.

PATIENT(S)

Ninety-one female patients on controlled ovarian hyperstimulation (COH).

INTERVENTION(S)

Sonoguided aspiration to collect the oocytes and the granulosa cells simultaneously.

MAIN OUTCOME MEASURE(S)

The RT-PCR data are normalized by comparing the intensity of the connexins to the intensity of internal controls (beta-actin). The follicles are grouped according to the size and the mRNA levels of the connexins. The correlations among the size of the follicles, the outcome of oocytes, and the mRNA levels of the connexins are compared by Fisher's exact test and Mann-Whitney test.

RESULT(S)

The mRNA levels of the connexins are low in the follicles equal or larger than 5.5 mL. High cx43 levels are linked to good prognosis of oocytes.

CONCLUSION(S)

The luteinized granulosa cells from the large follicles are relatively quiescent in the connexin mRNA expression. In addition to the volume, the mRNA levels of cx43 may serve as a marker to predict the outcome of oocytes.