A distinctive epigenetic ageing profile in human granulosa cells.
Hum Reprod
; 35(6): 1332-1345, 2020 06 01.
Article
in En
| MEDLINE
| ID: mdl-32474592
ABSTRACT
STUDY QUESTION Does women's age affect the DNA methylation (DNAm) profile differently in mural granulosa cells (MGCs) from other somatic cells? SUMMARY ANSWER Accumulation of epimutations by age and a higher number of age-related differentially methylated regions (DMR) in MGCs were found compared to leukocytes from the same woman, suggesting that the MGCs have a distinctive epigenetic profile. WHAT IS KNOWN ALREADY The mechanisms underlying the decline in women's fertility from the mid-30s remain to be fully elucidated. The DNAm age of many healthy tissues changes predictably with and follows chronological age, but DNAm age in some reproductive tissues has been shown to depart from chronological age (older endometrium; younger cumulus cells, spermatozoa). STUDY DESIGN, SIZE, DURATION This study is a multicenter cohort study based on retrospective analysis of prospectively collected data and material derived from healthy women undergoing IVF or ICSI treatment following ovarian stimulation with antagonist protocol. One hundred and nineteen women were included from September 2016 to June 2018 from four clinics in Denmark and Sweden. PARTICIPANTS/MATERIALS, SETTING, METHODS:
Blood samples were obtained from 118 healthy women with varying ovarian reserve status. MGCs were collected from 63 of the 119 women by isolation from pooled follicles immediately after oocyte retrieval. DNA from leukocytes and MGCs was extracted and analysed with a genome-wide methylation array. Data from the methylation array were processed using the ENmix package. Subsequently, DNAm age was calculated using established and tailored age predictors and DMRs were analysed with the DMRcate package. MAIN RESULTS AND ROLE OF CHANCE Using established age predictors, DNAm age in MGCs was found to be considerable younger and constant (average 2.7 years) compared to chronological age (average 33.9 years). A Granulosa Cell clock able to predict the age of both MGCs (average 32.4 years) and leukocytes (average 38.8 years) was successfully developed. MGCs differed from leukocytes in having a higher number of epimutations (P = 0.003) but predicted telomere lengths unaffected by age (Pearson's correlation coefficient = -0.1, P = 0.47). DMRs associated with age (age-DMRs) were identified in MGCs (n = 335) and in leukocytes (n = 1) with a significant enrichment in MGCs for genes involved in RNA processing (45 genes, P = 3.96 × 10-08) and gene expression (152 genes, P = 2.3 × 10-06). The top age-DMRs included the metastable epiallele VTRNA2-1, the DNAm regulator ZFP57 and the anti-Müllerian hormone (AMH) gene. The apparent discordance between different epigenetic measures of age in MGCs suggests that they reflect difference stages in the MGC life cycle. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION No gene expression data were available to associate with the epigenetic findings. The MGCs are collected during ovarian stimulation, which may influence DNAm; however, no correlation between FSH dose and number of epimutations was found. WIDER IMPLICATIONS OF THEFINDINGS:
Our findings underline that the somatic compartment of the follicle follows a different methylation trajectory with age than other somatic cells. The higher number of epimutations and age-DMRs in MGCs suggest that their function is affected by age. STUDY FUNDING/COMPETING INTEREST(S) This project is part of ReproUnion collaborative study, co-financed by the European Union, Interreg V ÖKS, the Danish National Research Foundation and the European Research Council. The authors declare no conflict of interest.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Aging
/
Granulosa Cells
Type of study:
Etiology_studies
/
Guideline
/
Incidence_studies
/
Observational_studies
/
Prognostic_studies
/
Risk_factors_studies
Limits:
Adult
/
Child, preschool
/
Female
/
Humans
/
Male
Country/Region as subject:
Europa
Language:
En
Journal:
Hum Reprod
Journal subject:
MEDICINA REPRODUTIVA
Year:
2020
Document type:
Article
Affiliation country:
Denmark