bims-cebooc 2024-07-07 papers

bims-cebooc

Biomed News

on Cell biology of oocytes

Issue of 2024‒07‒07
thirteen papers selected by
Gabriele Zaffagnini, Centre for Genomic Regulation

METAPHOR: Metabolic evaluation through phasor-based hyperspectral imaging and organelle recognition for mouse blastocysts and oocytes.
New insights into oocyte cytoplasmic lattice-associated proteins.
The germline coordinates mitokine signaling.
Maternal mRNA deadenylation is defective in in vitro matured mouse and human oocytes.
Roles of Tubulin Concentration during Prometaphase and Ran-GTP during Anaphase of Caenorhabditis elegans Meiosis.
Meiotic maturation failure in primary ovarian insufficiency: insights from a bovine model.
Expression profiling and function analysis identified new genes regulating cumulus expansion and apoptosis.
Transcriptome Dynamics and Cell Dialogs Between Oocytes and Granulosa Cells in Mouse Follicle Development.
ZP1-Y262C mutation causes abnormal zona pellucida formation and female infertility in humans.
Slit1 inhibits ovarian follicle development and female fertility in mice.
Extracellular signal-regulated protein kinase 5 modulates the spindle assembly to coordinate the oocyte meiotic maturation.
Fbxo28 is essential for spindle migration and morphology during mouse oocyte meiosis I.
The cell cycle oscillator and spindle length set the speed of chromosome separation in Drosophila embryos.

Proc Natl Acad Sci U S A. 2024 Jul 09. 121(28): e2315043121

METAPHOR: Metabolic evaluation through phasor-based hyperspectral imaging and organelle recognition for mouse blastocysts and oocytes.

Albert Parra, Denitza Denkova, Xavier P Burgos-Artizzu, Ester Aroca, Marc Casals, Amélie Godeau, Miguel Ares, Anna Ferrer-Vaquer, Ot Massafret, Irene Oliver-Vila, Enric Mestres, Mònica Acacio, Nuno Costa-Borges, Elena Rebollo, Hsiao Ju Chiang, Scott E Fraser, Francesco Cutrale, Anna Seriola, Samuel Ojosnegros.

  Only 30% of embryos from in vitro fertilized oocytes successfully implant and develop to term, leading to repeated transfer cycles. To reduce time-to-pregnancy and stress for patients, there is a need for a diagnostic tool to better select embryos and oocytes based on their physiology. The current standard employs brightfield imaging, which provides limited physiological information. Here, we introduce METAPHOR: Metabolic Evaluation through Phasor-based Hyperspectral Imaging and Organelle Recognition. This non-invasive, label-free imaging method combines two-photon illumination and AI to deliver the metabolic profile of embryos and oocytes based on intrinsic autofluorescence signals. We used it to classify i) mouse blastocysts cultured under standard conditions or with depletion of selected metabolites (glucose, pyruvate, lactate); and ii) oocytes from young and old mouse females, or in vitro-aged oocytes. The imaging process was safe for blastocysts and oocytes. The METAPHOR classification of control vs. metabolites-depleted embryos reached an area under the ROC curve (AUC) of 93.7%, compared to 51% achieved for human grading using brightfield imaging. The binary classification of young vs. old/in vitro-aged oocytes and their blastulation prediction using METAPHOR reached an AUC of 96.2% and 82.2%, respectively. Finally, organelle recognition and segmentation based on the flavin adenine dinucleotide signal revealed that quantification of mitochondria size and distribution can be used as a biomarker to classify oocytes and embryos. The performance and safety of the method highlight the accuracy of noninvasive metabolic imaging as a complementary approach to evaluate oocytes and embryos based on their physiology.

Keywords:  AI; hyperspectral imaging; in vitro fertilization; infertility; label-free imaging

DOI:  https://doi.org/10.1073/pnas.2315043121
Trends Genet. 2024 Jul 01. pii: S0168-9525(24)00149-5. [Epub ahead of print]

New insights into oocyte cytoplasmic lattice-associated proteins.

Carlo Giaccari, Francesco Cecere, Lucia Argenziano, Angela Pagano, Andrea Riccio.

  Oocyte maturation and preimplantation embryo development are critical to successful pregnancy outcomes and the correct establishment and maintenance of genomic imprinting. Thanks to novel technologies and omics studies in human patients and mouse models, the importance of the proteins associated with the cytoplasmic lattices (CPLs), highly abundant structures found in the cytoplasm of mammalian oocytes and preimplantation embryos, in the maternal to zygotic transition is becoming increasingly evident. This review highlights the recent discoveries on the role of these proteins in protein storage and other oocyte cytoplasmic processes, epigenetic reprogramming, and zygotic genome activation (ZGA). A better comprehension of these events may significantly improve clinical diagnosis and pave the way for targeted interventions aiming to correct or mitigate female fertility issues and genomic imprinting disorders.

Keywords:  UHRF1; cytoplasmic lattices; genomic imprinting disorders; oocyte maturation; subcortical maternal complex; zygotic genome activation

DOI:  https://doi.org/10.1016/j.tig.2024.06.002
Cell. 2024 Jun 26. pii: S0092-8674(24)00650-0. [Epub ahead of print]

The germline coordinates mitokine signaling.

Koning Shen, Jenni Durieux, Cesar G Mena, Brant M Webster, C Kimberly Tsui, Hanlin Zhang, Larry Joe, Kristen M Berendzen, Andrew Dillin.

  The ability of mitochondria to coordinate stress responses across tissues is critical for health. In C. elegans, neurons experiencing mitochondrial stress elicit an inter-tissue signaling pathway through the release of mitokine signals, such as serotonin or the Wnt ligand EGL-20, which activate the mitochondrial unfolded protein response (UPRMT) in the periphery to promote organismal health and lifespan. We find that germline mitochondria play a surprising role in neuron-to-periphery UPRMT signaling. Specifically, we find that germline mitochondria signal downstream of neuronal mitokines, Wnt and serotonin, and upstream of lipid metabolic pathways in the periphery to regulate UPRMT activation. We also find that the germline tissue itself is essential for UPRMT signaling. We propose that the germline has a central signaling role in coordinating mitochondrial stress responses across tissues, and germline mitochondria play a defining role in this coordination because of their inherent roles in germline integrity and inter-tissue signaling.

Keywords:  C. elegans; aging; germline; lipids; mitochondria; mtUPR; proteostasis; stress response

DOI:  https://doi.org/10.1016/j.cell.2024.06.010
Nat Commun. 2024 Jul 02. 15(1): 5550

Maternal mRNA deadenylation is defective in in vitro matured mouse and human oocytes.

Yusheng Liu, Wenrong Tao, Shuang Wu, Yiwei Zhang, Hu Nie, Zhenzhen Hou, Jingye Zhang, Zhen Yang, Zi-Jiang Chen, Jiaqiang Wang, Falong Lu, Keliang Wu.

Oocyte in vitro maturation is a technique in assisted reproductive technology. Thousands of genes show abnormally high expression in in vitro maturated metaphase II (MII) oocytes compared to those matured in vivo in bovines, mice, and humans. The mechanisms underlying this phenomenon are poorly understood. Here, we use poly(A) inclusive RNA isoform sequencing (PAIso-seq) for profiling the transcriptome-wide poly(A) tails in both in vivo and in vitro matured mouse and human oocytes. Our results demonstrate that the observed increase in maternal mRNA abundance is caused by impaired deadenylation in in vitro MII oocytes. Moreover, the cytoplasmic polyadenylation of dormant Btg4 and Cnot7 mRNAs, which encode key components of deadenylation machinery, is impaired in in vitro MII oocytes, contributing to reduced translation of these deadenylase machinery components and subsequently impaired global maternal mRNA deadenylation. Our findings highlight impaired maternal mRNA deadenylation as a distinct molecular defect in in vitro MII oocytes.

DOI: https://doi.org/10.1038/s41467-024-49695-y
Life Sci Alliance. 2024 Sep;pii: e202402884. [Epub ahead of print]7(9):

Roles of Tubulin Concentration during Prometaphase and Ran-GTP during Anaphase of Caenorhabditis elegans Meiosis.

Ting Gong, Karen L McNally, Siri Konanoor, Alma Peraza, Cynthia Bailey, Stefanie Redemann, Francis J McNally.

In many animal species, the oocyte meiotic spindle, which is required for chromosome segregation, forms without centrosomes. In some systems, Ran-GEF on chromatin initiates spindle assembly. We found that in Caenorhabditis elegans oocytes, endogenously-tagged Ran-GEF dissociates from chromatin during spindle assembly but re-associates during meiotic anaphase. Meiotic spindle assembly occurred after auxin-induced degradation of Ran-GEF, but anaphase I was faster than controls and extrusion of the first polar body frequently failed. In search of a possible alternative pathway for spindle assembly, we found that soluble tubulin concentrates in the nuclear volume during germinal vesicle breakdown. We found that the concentration of soluble tubulin in the metaphase spindle region is enclosed by ER sheets which exclude cytoplasmic organelles including mitochondria and yolk granules. Measurement of the volume occupied by yolk granules and mitochondria indicated that volume exclusion would be sufficient to explain the concentration of tubulin in the spindle volume. We suggest that this concentration of soluble tubulin may be a redundant mechanism promoting spindle assembly near chromosomes.

DOI: https://doi.org/10.26508/lsa.202402884
J Assist Reprod Genet. 2024 Jun 29.

Meiotic maturation failure in primary ovarian insufficiency: insights from a bovine model.

Sara Pietroforte, Pritha Dey, Elena Ibáñez, Alberto Maria Luciano, Valentina Lodde, Federica Franciosi, Mina Popovic, Rita Vassena, Filippo Zambelli.

  PURPOSE: Oocytes from women presenting primary ovarian insufficiency (POI) generate viable embryos at a lower rate than non-POI women, but the mechanisms responsible for the lower oocyte quality remain elusive. Due to the scarcity of human oocytes for research, animal models provide a promising way forward. We aimed at investigating the molecular events characterizing final maturation in POI oocytes in a well-defined POI-like bovine model.METHODS: Single-cell RNA-sequencing of bovine control and POI-like, GV, and MII oocytes (n = 5 per group) was performed. DEseq2 was used to identify differentially expressed genes. Further, a Gene set enrichment analysis and a transcriptomic meta-analysis between bovine and human oocytes were performed.
RESULTS: In control cows, we found 2223 differentially expressed genes between the GV and MII stages. Specifically, the affected genes were related to RNA processing and transport, protein synthesis, organelle remodeling and reorganization, and metabolism. The meta-analysis with a set of young human oocytes at different maturation stages revealed 315 conserved genes through the GV-MII transition in cows and humans, mostly related to meiotic progression and cell cycle. Gene expression analysis between GV and MII of POI-like oocytes showed no differences in terms of differentially expressed genes, pointing towards a substantial failure to properly remodel the transcriptome in the POI model, and with the clustering analysis indicating that the cow's genetic background had a higher impact than the oocyte's maturation stage.
CONCLUSION: Overall, we have identified and characterized a valuable animal model of POI, paving the way to identifying new molecular mechanisms involved in POI.

Keywords:  Bovine; Meiosis; Oocyte; Oocyte competence; Primary ovarian insufficiency; Transcriptome

DOI:  https://doi.org/10.1007/s10815-024-03160-3
Reproduction. 2024 Jul 01. pii: REP-24-0128. [Epub ahead of print]

Expression profiling and function analysis identified new genes regulating cumulus expansion and apoptosis.

Min Zhang, Jia-Shun Wu, Xiao Han, Rui-Jie Ma, Jia-Li Xu, Ming-Tao Xu, Hong-Jie Yuan, Ming-Jiu Luo, Jing-He Tan.

Studies on the mechanisms behind cumulus expansion and cumulus cell (CC) apoptosis are essential for understanding the mechanisms for oocyte maturation. Genes expressed in CCs might be used as markers for competent oocytes and/or embryos. In this study, both in vitro (IVT) and in vivo (IVO) mouse oocyte models with significant difference in cumulus expansion and CC apoptosis were used to identify and validate new genes regulating cumulus expansion and CC apoptosis of mouse oocytes. We first performed mRNA sequencing and bioinformatic analysis using the IVT oocyte model to identify candidate genes. We then analyzed functions of the candidate genes by RNAi or gene overexpression to select the candidate cumulus expansion and CC apoptosis-regulating genes. Finally, we validated the cumulus expansion and CC apoptosis-regulating genes using the IVO oocyte model. The results showed that while Spp1, Sdc1, Ldlr, Ezr and Mmp2 promoted, Bmp2, Angpt2, Edn1, Itgb8, Cxcl10 and Agt inhibited cumulus expansion. Furthermore, Spp1, Sdc1 and Ldlr inhibited CC apoptosis. In conclusion, by using both IVT and IVO oocyte models, we have identified and validated a new group of cumulus expansion and/or apoptosis-regulating genes, which may be used for selection of quality oocytes/embryos and for elucidating the molecular mechanisms behind oocyte maturation.

DOI: https://doi.org/10.1530/REP-24-0128
Genomics Proteomics Bioinformatics. 2024 Jul 02. pii: qzad001. [Epub ahead of print]22(2):

Transcriptome Dynamics and Cell Dialogs Between Oocytes and Granulosa Cells in Mouse Follicle Development.

Wenju Liu, Chuan Chen, Yawei Gao, Xinyu Cui, Yuhan Zhang, Liang Gu, Yuanlin He, Jing Li, Shaorong Gao, Rui Gao, Cizhong Jiang.

  The development and maturation of follicles is a sophisticated and multistage process. The dynamic gene expression of oocytes and their surrounding somatic cells and the dialogs between these cells are critical to this process. In this study, we accurately classified the oocyte and follicle development into nine stages and profiled the gene expression of mouse oocytes and their surrounding granulosa cells and cumulus cells. The clustering of the transcriptomes showed the trajectories of two distinct development courses of oocytes and their surrounding somatic cells. Gene expression changes precipitously increased at Type 4 stage and drastically dropped afterward within both oocytes and granulosa cells. Moreover, the number of differentially expressed genes between oocytes and granulosa cells dramatically increased at Type 4 stage, most of which persistently passed on to the later stages. Strikingly, cell communications within and between oocytes and granulosa cells became active from Type 4 stage onward. Cell dialogs connected oocytes and granulosa cells in both unidirectional and bidirectional manners. TGFB2/3, TGFBR2/3, INHBA/B, and ACVR1/1B/2B of TGF-β signaling pathway functioned in the follicle development. NOTCH signaling pathway regulated the development of granulosa cells. Additionally, many maternally DNA methylation- or H3K27me3-imprinted genes remained active in granulosa cells but silent in oocytes during oogenesis. Collectively, Type 4 stage is the key turning point when significant transcription changes diverge the fate of oocytes and granulosa cells, and the cell dialogs become active to assure follicle development. These findings shed new insights on the transcriptome dynamics and cell dialogs facilitating the development and maturation of oocytes and follicles.

Keywords:  Cell dialog; Folliculogenesis; Granulosa cell; Oocyte; Transcriptome

DOI:  https://doi.org/10.1093/gpbjnl/qzad001
Front Genet. 2024 ;15 1407202

ZP1-Y262C mutation causes abnormal zona pellucida formation and female infertility in humans.

Guangyi Cao, Lina Yu, Junshun Fang, Ruixin Shi, Huijun Li, Feifei Lu, Xiaoyue Shen, Xiangyu Zhu, Shanshan Wang, Na Kong.

  Defective oocyte maturation is a common cause of female infertility. The loss of the zona pellucida (ZP) represents a specific condition of impaired oocyte maturation. The extracellular matrix known as the ZP envelops mammalian oocytes and preimplantation embryos, exerting significant influence on oogenesis, fertilization, and embryo implantation. However, the genetic factors leading to the loss of the ZP in oocytes are not well understood. This study focused on patients who underwent oocyte retrieval surgery after ovarian stimulation and were found to have abnormal oocyte maturation without the presence of the ZP. Ultrasonography was performed during the surgical procedure to evaluate follicle development. Peripheral blood samples from the patient were subjected to exome sequencing. Here, a novel, previously unreported heterozygous mutation in the ZP1 gene was identified. Within the ZP1 gene, we discovered a novel heterozygous mutation (ZP1 NM_207341.4:c.785A>G (p.Y262C)), specifically located in the trefoil domain. Bioinformatics comparisons further revealed conservation of the ZP1-Y262C mutation across different species. Model predictions of amino acid mutations on protein structure and cell immunofluorescence/western blot experiments collectively confirmed the detrimental effects of the ZP1-Y262C mutation on the function and expression of the ZP1 protein. The ZP1-Y262C mutation represents the novel mutation in the trefoil domain of the ZP1 protein, which is associated with defective oocyte maturation in humans. Our report enhances comprehension regarding the involvement of ZP-associated genes in female infertility and offers enriched understanding for the genetic diagnosis of this condition.

Keywords:  ZP1; infertility; oocyte; reproduction; zona pellucida

DOI:  https://doi.org/10.3389/fgene.2024.1407202
Biol Reprod. 2024 Jun 29. pii: ioae106. [Epub ahead of print]

Slit1 inhibits ovarian follicle development and female fertility in mice.

Florine Grudet, Emmanuelle Martinot, Philippe Godin, Michael Bérubé, Alain Chédotal, Derek Boerboom.

  Previous in vitro studies have suggested that SLIT ligands could play roles in regulating ovarian granulosa cell proliferation and gene expression, as well as luteolysis. However, no in vivo study of Slit gene function has been conducted to date. Here we investigated the potential role of Slit1 in ovarian biology using a Slit1-null mouse model. Female Slit1-null mice were found to produce larger litters than their wild-type counterparts due to increased ovulation rates. Increased ovarian weights in Slit1-null animals were found to be due to the presence of greater numbers of healthy antral follicles with similar numbers of atretic ones, suggesting both an increased rate of follicle recruitment and a decreased rate of atresia. Consistent with this, treatment of cultured granulosa cells with exogenous SLIT1 induced apoptosis in presence or absence of FSH, but had no effect on cell proliferation. Although few alterations in the mRNA levels of FSH-responsive genes were noted in granulosa cells of Slit1-null mice, LH target gene mRNA levels were greatly increased. Finally, increased phospho-AKT levels were found in granulosa cells isolated from Slit1-null mice, and SLIT1 pretreatment of cultured granulosa cells inhibited the ability of both FSH and LH to increase AKT phosphorylation, suggesting a mechanism whereby SLIT1 could antagonize gonadotropin signaling. These findings therefore represent the first evidence for a physiological role of a SLIT ligand in the ovary, and define Slit1 as a novel autocrine/paracrine regulator of follicle development.

Keywords:  Slit1; atresia; follicle; mouse; ovary; ovulation; progesterone

DOI:  https://doi.org/10.1093/biolre/ioae106
Theriogenology. 2024 Jun 27. pii: S0093-691X(24)00261-9. [Epub ahead of print]226 335-342

Extracellular signal-regulated protein kinase 5 modulates the spindle assembly to coordinate the oocyte meiotic maturation.

Xia Wang, Xiayan ShiYang, Wei Ma, Xue Wu, Yajuan Lu.

  Extracellular signal-regulated protein kinase 5 (Erk5), a member of the mitogen-activated protein kinase (MAPK) family, is ubiquitously expressed in all eukaryotic cells and is implicated in the various mitotic processes such as cell survival, proliferation, migration, and differentiation. However, the potential functional roles of Erk5 in oocyte meiosis have not been fully determined. In this study, we document that ERK5 participates in the meiotic maturation of mouse oocytes by regulating the spindle assembly to ensure the meiotic progression. We unexpectedly found that phosphorylated ERK5 was localized in the spindle pole region at metaphase I and II stages by immunostaining analysis. Inhibition of ERK5 activity using its specific inhibitor XMD8-92 dramatically reduced the incidence of first polar body extrusion. In addition, inhibition of ERK5 evoked the spindle assembly checkpoint to arrest oocytes at metaphase I stage by impairing the spindle assembly, chromosome alignment and kinetochore-microtubule attachment. Mechanically, over-strengthened microtubule stability was shown to disrupt the microtubule dynamics and thus compromise the spindle assembly in ERK5-inhibited oocytes. Conversely, overexpression of ERK5 caused decreased level of acetylated α-tubulin and spindle defects. Collectively, we conclude that ERK5 plays an important role in the oocyte meiotic maturation by regulating microtubule dynamics and spindle assembly.

Keywords:  ERK5; Microtubule stability; Oocyte meiotic maturation; Spindle assembly; XMD8-92

DOI:  https://doi.org/10.1016/j.theriogenology.2024.06.028
Int J Biol Macromol. 2024 Jul 01. pii: S0141-8130(24)04037-6. [Epub ahead of print] 133232

Fbxo28 is essential for spindle migration and morphology during mouse oocyte meiosis I.

Haoya Chang, Chenyang Huang, Siyu Cheng, Jian Li, Xiaohong Wang.

  Spindle migration and assembly regulates asymmetric oocyte division, which is essential for fertility. Fbxo28, as a member of SCF (Skp1-Cul1-F-box) ubiquitin E3 ligases complex, is specifically expressed in oocytes. However, little is known about the functions of Fbxo28 in spindle assembly and migration during oocyte meiosis I. In present study, microinjection with morpholino oligonucleotides and exogenous mRNA for knockdown and rescue experiments, and immunofluorescence staining, western blot, timelapse confocal microscopy and chromosome spreading were utilized to explore the roles of Fbxo28 in asymmetric division during meiotic maturation. Our data suggested that Fbxo28 mainly localized at chromosomes and acentriolar microtubule-organizing centers (aMTOCs). Depletion of Fbxo28 did not affect polar body extrusion but caused defects in spindle morphology and migration, indicative of the failure of asymmetric division. Moreover, absence of Fbxo28 disrupted both cortical and cytoplasmic actin assembly and decreased the expression of ARPC2 and ARP3. These defects could be rescued by exogenous Fbxo28-myc mRNA supplement. Collectively, this study demonstrated that Fbxo28 affects spindle morphology and actin-based spindle migration during mouse oocyte meiotic maturation.

Keywords:  Aneuploidy; Fbxo28; Meiosis progression; Mouse oocyte; Spindle migration

DOI:  https://doi.org/10.1016/j.ijbiomac.2024.133232
bioRxiv. 2024 Jun 18. pii: 2024.06.17.598879. [Epub ahead of print]

The cell cycle oscillator and spindle length set the speed of chromosome separation in Drosophila embryos.

Yitong Xu, Anna Chao, Melissa Rinaldin, Alison Kickuth, Jan Brugués, Stefano Di Talia.

Anaphase is tightly controlled in space and time to ensure proper separation of chromosomes. The mitotic spindle, the self-organized microtubule structure driving chromosome segregation, scales in size with the available cytoplasm. Yet, the relationship between spindle size and chromosome movement remains poorly understood. Here, we address how the movement of chromosomes changes during the cleavage divisions of the Drosophila blastoderm. We show that the speed of chromosome separation gradually decreases during the 4 nuclear divisions of the blastoderm. This reduction in speed is accompanied by a similar reduction in the length of the spindle, thus ensuring that these two quantities are tightly linked. Using a combination of genetic and quantitative imaging approaches, we find that two processes contribute to controlling the speed at which chromosomes move at mitotic exit: the activity of molecular motors important for microtubule depolymerization and the cell cycle oscillator. Specifically, we found that the levels of Klp10A, Klp67A, and Klp59C, three kinesin-like proteins important for microtubule depolymerization, contribute to setting the speed of chromosome separation. This observation is supported by quantification of microtubule dynamics indicating that poleward flux rate scales with the length of the spindle. Perturbations of the cell cycle oscillator using heterozygous mutants of mitotic kinases and phosphatases revealed that the duration of anaphase increases during the blastoderm cycles and is the major regulator of chromosome velocity. Thus, our work suggests a potential link between the biochemical rate of mitotic exit and the forces exerted by the spindle. Collectively, we propose that the cell cycle oscillator and spindle length set the speed of chromosome separation in anaphase.

DOI: https://doi.org/10.1101/2024.06.17.598879