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Proteome of fluid from human ovarian small antral follicles reveals insights in folliculogenesis and oocyte maturation

Pla, Indira LU orcid ; Sanchez, Aniel LU ; Pors, Susanne Elisabeth ; Pawlowski, Krzysztof LU ; Appelqvist, Roger LU ; Sahlin, K Barbara LU ; Poulsen, Liv La Cour ; Marko-Varga, György LU ; Andersen, Claus Yding and Malm, Johan LU (2021) In Human Reproduction 36(3). p.756-770
Abstract

STUDY QUESTION: Is it possible to identify by mass spectrometry a wider range of proteins and key proteins involved in folliculogenesis and oocyte growth and development by studying follicular fluid (FF) from human small antral follicles (hSAF)?

SUMMARY ANSWER: The largest number of proteins currently reported in human FF was identified in this study analysing hSAF where several proteins showed a strong relationship with follicular developmental processes.

WHAT IS KNOWN ALREADY: Protein composition of human ovarian FF constitutes the microenvironment for oocyte development. Previous proteomics studies have analysed fluids from pre-ovulatory follicles, where large numbers of plasma constituents are transferred through the... (More)

STUDY QUESTION: Is it possible to identify by mass spectrometry a wider range of proteins and key proteins involved in folliculogenesis and oocyte growth and development by studying follicular fluid (FF) from human small antral follicles (hSAF)?

SUMMARY ANSWER: The largest number of proteins currently reported in human FF was identified in this study analysing hSAF where several proteins showed a strong relationship with follicular developmental processes.

WHAT IS KNOWN ALREADY: Protein composition of human ovarian FF constitutes the microenvironment for oocyte development. Previous proteomics studies have analysed fluids from pre-ovulatory follicles, where large numbers of plasma constituents are transferred through the follicular basal membrane. This attenuates the detection of low abundant proteins, however, the basal membrane of small antral follicles is less permeable, making it possible to detect a large number of proteins, and thereby offering further insights in folliculogenesis.

STUDY DESIGN, SIZE, DURATION: Proteins in FF from unstimulated hSAF (size 6.1 ± 0.4 mm) were characterised by mass spectrometry, supported by high-throughput and targeted proteomics and bioinformatics. The FF protein profiles from hSAF containing oocytes, capable or not of maturing to metaphase II of the second meiotic division during an IVM (n = 13, from 6 women), were also analysed.

PARTICIPANTS/MATERIALS, SETTING, METHODS: We collected FF from hSAF of ovaries that had been surgically removed from 31 women (∼28.5 years old) undergoing unilateral ovariectomy for fertility preservation.

MAIN RESULTS AND THE ROLE OF CHANCE: In total, 2461 proteins were identified, of which 1108 identified for the first time in FF. Of the identified proteins, 24 were related to follicular regulatory processes. A total of 35 and 65 proteins were down- and up-regulated, respectively, in fluid from hSAF surrounding oocytes capable of maturing (to MII). We found that changes at the protein level occur already in FF from small antral follicles related to subsequent oocyte maturation.

LIMITATIONS, REASONS FOR CAUTION: A possible limitation of our study is the uncertainty of the proportion of the sampled follicles that are undergoing atresia. Although the FF samples were carefully aspirated and processed to remove possible contaminants, we cannot ensure the absence of some proteins derived from cellular lysis provoked by technical reasons.

WIDER IMPLICATIONS OF THE FINDINGS: This study is, to our knowledge, the first proteomics characterisation of FF from hSAF obtained from women in their natural menstrual cycle. We demonstrated that the analysis by mass spectrometry of FF from hSAF allows the identification of a greater number of proteins compared to the results obtained from previous analyses of larger follicles. Significant differences found at the protein level in hSAF fluid could predict the ability of the enclosed oocyte to sustain meiotic resumption. If this can be confirmed in further studies, it demonstrates that the viability of the oocyte is determined early on in follicular development and this may open up new pathways for augmenting or attenuating subsequent oocyte viability in the pre-ovulatory follicle ready to undergo ovulation.

STUDY FUNDING/COMPETING INTEREST(S): The authors thank the financial support from ReproUnion, which is funded by the Interreg V EU programme. No conflict of interest was reported by the authors.

TRIAL REGISTRATION NUMBER: N/A.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Adult, Female, Follicular Fluid, Humans, Oocytes, Oogenesis, Ovarian Follicle, Proteome
in
Human Reproduction
volume
36
issue
3
pages
756 - 770
publisher
Oxford University Press
external identifiers
  • scopus:85102213101
  • pmid:33313811
ISSN
0268-1161
DOI
10.1093/humrep/deaa335
language
English
LU publication?
yes
additional info
© The Author(s) 2020. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology.
id
7e91a57c-9cef-4ec1-95a0-1bf673ef0a4d
date added to LUP
2021-10-19 18:46:26
date last changed
2024-06-15 18:29:05
@article{7e91a57c-9cef-4ec1-95a0-1bf673ef0a4d,
  abstract     = {{<p>STUDY QUESTION: Is it possible to identify by mass spectrometry a wider range of proteins and key proteins involved in folliculogenesis and oocyte growth and development by studying follicular fluid (FF) from human small antral follicles (hSAF)?</p><p>SUMMARY ANSWER: The largest number of proteins currently reported in human FF was identified in this study analysing hSAF where several proteins showed a strong relationship with follicular developmental processes.</p><p>WHAT IS KNOWN ALREADY: Protein composition of human ovarian FF constitutes the microenvironment for oocyte development. Previous proteomics studies have analysed fluids from pre-ovulatory follicles, where large numbers of plasma constituents are transferred through the follicular basal membrane. This attenuates the detection of low abundant proteins, however, the basal membrane of small antral follicles is less permeable, making it possible to detect a large number of proteins, and thereby offering further insights in folliculogenesis.</p><p>STUDY DESIGN, SIZE, DURATION: Proteins in FF from unstimulated hSAF (size 6.1 ± 0.4 mm) were characterised by mass spectrometry, supported by high-throughput and targeted proteomics and bioinformatics. The FF protein profiles from hSAF containing oocytes, capable or not of maturing to metaphase II of the second meiotic division during an IVM (n = 13, from 6 women), were also analysed.</p><p>PARTICIPANTS/MATERIALS, SETTING, METHODS: We collected FF from hSAF of ovaries that had been surgically removed from 31 women (∼28.5 years old) undergoing unilateral ovariectomy for fertility preservation.</p><p>MAIN RESULTS AND THE ROLE OF CHANCE: In total, 2461 proteins were identified, of which 1108 identified for the first time in FF. Of the identified proteins, 24 were related to follicular regulatory processes. A total of 35 and 65 proteins were down- and up-regulated, respectively, in fluid from hSAF surrounding oocytes capable of maturing (to MII). We found that changes at the protein level occur already in FF from small antral follicles related to subsequent oocyte maturation.</p><p>LIMITATIONS, REASONS FOR CAUTION: A possible limitation of our study is the uncertainty of the proportion of the sampled follicles that are undergoing atresia. Although the FF samples were carefully aspirated and processed to remove possible contaminants, we cannot ensure the absence of some proteins derived from cellular lysis provoked by technical reasons.</p><p>WIDER IMPLICATIONS OF THE FINDINGS: This study is, to our knowledge, the first proteomics characterisation of FF from hSAF obtained from women in their natural menstrual cycle. We demonstrated that the analysis by mass spectrometry of FF from hSAF allows the identification of a greater number of proteins compared to the results obtained from previous analyses of larger follicles. Significant differences found at the protein level in hSAF fluid could predict the ability of the enclosed oocyte to sustain meiotic resumption. If this can be confirmed in further studies, it demonstrates that the viability of the oocyte is determined early on in follicular development and this may open up new pathways for augmenting or attenuating subsequent oocyte viability in the pre-ovulatory follicle ready to undergo ovulation.</p><p>STUDY FUNDING/COMPETING INTEREST(S): The authors thank the financial support from ReproUnion, which is funded by the Interreg V EU programme. No conflict of interest was reported by the authors.</p><p>TRIAL REGISTRATION NUMBER: N/A.</p>}},
  author       = {{Pla, Indira and Sanchez, Aniel and Pors, Susanne Elisabeth and Pawlowski, Krzysztof and Appelqvist, Roger and Sahlin, K Barbara and Poulsen, Liv La Cour and Marko-Varga, György and Andersen, Claus Yding and Malm, Johan}},
  issn         = {{0268-1161}},
  keywords     = {{Adult; Female; Follicular Fluid; Humans; Oocytes; Oogenesis; Ovarian Follicle; Proteome}},
  language     = {{eng}},
  number       = {{3}},
  pages        = {{756--770}},
  publisher    = {{Oxford University Press}},
  series       = {{Human Reproduction}},
  title        = {{Proteome of fluid from human ovarian small antral follicles reveals insights in folliculogenesis and oocyte maturation}},
  url          = {{http://dx.doi.org/10.1093/humrep/deaa335}},
  doi          = {{10.1093/humrep/deaa335}},
  volume       = {{36}},
  year         = {{2021}},
}