GO:0090427 activation of meiosis: Initiation of Meiosis, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0090427 activation of meiosis describes any process that starts the inactive process of meiosis, a specialized cell division that produces haploid gametes.
• Activation of meiosis is controlled by transcriptional reprogramming, kinase signaling, and cell-cycle machinery that licenses two consecutive divisions without an intervening S phase.
• Key regulators include Ume6, Spo13/MEIKIN, Aurora-A, APC/C, MAP kinase, and RAB7, which coordinate entry, progression, and quality control.
• Defects in meiotic activation are linked to aneuploidy, infertility, and ovarian aging, making this process clinically relevant.
• CRISPR knockout, point mutation, knock-in, and overexpression models enable causal testing of candidate meiotic activators.
• Studying activation of meiosis requires integrated approaches such as live imaging, phosphoproteomics, and RNA-seq to capture dynamic initiation events.
Description
Activation of meiosis (GO:0090427) is the biological process that triggers the transition from an inactive, non-meiotic state into the specialized two-division program that generates haploid gametes. This process is essential for sexual reproduction and is tightly regulated to ensure that DNA replication is followed by two rounds of chromosome segregation without an intervening S phase. In organisms ranging from yeast to mammals, activation of meiosis involves transcriptional induction of early meiotic genes, activation of kinases, and remodeling of the cell-cycle machinery. Researchers study activation of meiosis to understand fertility, aneuploidy, and the quality-control mechanisms that eliminate defective gametes. Because errors in meiotic initiation can lead to miscarriage, developmental disorders, and age-related decline in oocyte quality, this GO term is a focal point for reproductive biology and cancer research.
activation of meiosis At A Glance
| GO ID | GO:0090427 |
|---|---|
| GO term | activation of meiosis |
| Ontology | biological_process |
| Synonym | none |
| Major function | Initiates the inactive process of meiosis, committing cells to a specialized two-division program that produces haploid gametes |
| Related processes | Meiotic cell cycle, gametogenesis, cell-cycle checkpoint control, transcriptional reprogramming |
| Key regulators | Ume6, Spo13/MEIKIN, Aurora-A, APC/C, MAP kinase, RAB7 |
| Disease relevance | Aneuploidy, infertility, ovarian aging, and meiotic errors in cancer |
What Is GO:0090427?
According to the Gene Ontology, activation of meiosis (GO:0090427) is defined as any process that starts the inactive process of meiosis. In other words, it encompasses the molecular events that switch a cell from a non-meiotic state into the active meiotic program, including the transcriptional, signaling, and cell-cycle changes that commit a cell to undergo meiosis.
Why Is activation of meiosis Important in Cell Biology?
Activation of meiosis is a critical decision point in gametogenesis because it determines whether a cell will enter the meiotic program and ultimately produce viable gametes. Errors in this process can cause chromosome missegregation, aneuploidy, and infertility, and are associated with age-related decline in oocyte quality. Understanding the molecular triggers of meiotic activation also informs cancer biology, as ectopic activation of meiotic programs can occur in tumors.
• Controls the initiation of meiosis, a prerequisite for sexual reproduction and genetic diversity.
• Prevents inappropriate meiotic entry in non-germline cells, which could lead to genomic instability.
• Coordinates the two meiotic divisions without an intervening S phase, a unique cell-cycle feature.
• Regulates oocyte quality control and mitophagy during ovarian aging.
• Dysregulation is linked to aneuploidy, miscarriage, and infertility.
• Provides targets for contraceptive development and fertility preservation.
• Serves as a model for studying cell-cycle transitions and kinase signaling.
• Informs cancer research because ectopic meiotic activation can drive tumor heterogeneity.
• Enables CRISPR-based functional genomics of fertility genes.
• Supports evolutionary studies of sexual reproduction across species.
What Happens During activation of meiosis?
Transcriptional commitment to meiosis
In simple terms: The cell flips a genetic switch that turns on the meiosis program.
Activation of meiosis begins with transcriptional reprogramming that induces early meiosis-specific genes. In Saccharomyces cerevisiae, Ume6 acts as a stable platform to coordinate repression and activation of early meiosis-specific genes, ensuring that cells commit to meiosis only under appropriate conditions. This transcriptional switch is a hallmark of meiotic entry and is conserved in principle across eukaryotes.
Kinase signaling and cell-cycle licensing
In simple terms: Signaling enzymes give the green light for the cell to start dividing meiotically.
Kinase cascades, including the pheromone-responsive MAP kinase in fission yeast, drive haploid cells to undergo ectopic meiosis with normal telomere clustering and sister chromatid segregation. Aurora-A kinase is biphasically activated during the meiosis I to meiosis II transition in Xenopus oocytes, highlighting the role of kinase waves in meiotic progression. These signaling events license the cell-cycle machinery for two consecutive divisions.
APC/C regulation and meiotic divisions
In simple terms: The cell's recycling machinery is retuned so that two divisions happen without a DNA-copying step in between.
The anaphase-promoting complex/cyclosome (APC/C) is a key regulator of meiotic progression. In Xenopus oocytes, activation of APC/C and degradation of cyclin B is not required for progression from meiosis I to II, revealing a specialized meiotic cell-cycle control. Spo13/MEIKIN ensures a two-division meiosis by preventing the activation of APC/C(Ama1) at meiosis I, thereby maintaining the meiotic program.
Quality control and mitophagy
In simple terms: The cell checks its organelles and removes damaged mitochondria to keep the egg healthy.
RAB7 activity is required for the regulation of mitophagy in oocyte meiosis and oocyte quality control during ovarian aging. This quality-control step is coupled to meiotic activation and ensures that only healthy oocytes proceed through the meiotic program.
Egg activation at fertilization
In simple terms: After fertilization, the egg is activated to complete meiosis.
Egg activation at fertilization triggers the completion of meiosis and the onset of embryonic development. This process involves calcium signaling and downstream events that restart the cell cycle, linking meiotic activation to the broader context of fertilization.
Key Genes Involved in GO:0090427 activation of meiosis
The following genes and proteins are experimentally implicated in the activation and regulation of meiosis across model organisms.
| Gene | Major Role | Research Relevance |
|---|---|---|
| UME6 | Transcriptional platform coordinating repression and activation of early meiosis-specific genes in Saccharomyces cerevisiae | Key model for studying meiotic commitment and transcriptional switches |
| SPO13/MEIKIN | Prevents APC/C(Ama1) activation at meiosis I to ensure two-division meiosis | Critical for understanding meiotic chromosome segregation and aneuploidy |
| AURKA | Biphasic activation during meiosis I to meiosis II transition in Xenopus oocytes | Target for studying kinase waves and meiotic progression |
| APC/C | Ubiquitin ligase regulating cyclin degradation and meiotic transitions | Model for cell-cycle control without S phase |
| MAPK | Pheromone-responsive MAP kinase drives ectopic meiosis in fission yeast | Used to study signaling-induced meiotic entry |
| RAB7 | Regulates mitophagy and oocyte quality control during ovarian aging | Links meiotic activation to organelle quality control |
| MOS | Proto-oncogene kinase that maintains meiotic arrest in oocytes | Studied in egg activation and fertilization |
| CDK1 | Cyclin-dependent kinase that drives meiotic divisions | Central to cell-cycle regulation in oocytes |
| CCNB1 | Cyclin B, partner of CDK1, degraded by APC/C | Marker of meiotic progression |
| PLK1 | Polo-like kinase involved in meiotic spindle assembly | Target for spindle checkpoint studies |
| BUB1 | Spindle assembly checkpoint kinase ensuring accurate chromosome segregation | Relevant to aneuploidy research |
| REC8 | Meiotic cohesin subunit required for sister chromatid cohesion | Key for studying recombination and segregation |
| DMC1 | Meiotic recombinase essential for homologous recombination | Marker of meiotic prophase |
| IME1 | Master transcriptional activator of meiosis in yeast | Model for meiotic entry control |
| IME2 | Meiosis-specific kinase regulated by Ime1 | Studied in meiotic initiation |
| NDT80 | Transcription factor required for exit from pachytene | Used to study meiotic progression |
| SPO11 | Catalyzes meiotic double-strand breaks | Central to recombination and checkpoint activation |
How Is activation of meiosis Regulated?
Activation of meiosis is regulated at multiple levels. Transcriptional control by Ume6 and Ime1 ensures that early meiosis-specific genes are expressed only under appropriate conditions. Kinase signaling, including MAP kinase and Aurora-A, provides post-translational regulation that coordinates meiotic entry with cell-cycle progression. The APC/C and its regulators, such as Spo13/MEIKIN, control the timing of meiotic divisions by preventing premature activation of APC/C(Ama1) at meiosis I. Additionally, RAB7-dependent mitophagy acts as a quality-control mechanism during ovarian aging, linking metabolic and organelle status to meiotic activation.
activation of meiosis and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RAB7 | Ovarian aging and oocyte quality decline | Knockout or point-mutation oocyte models to assess mitophagy |
| SPO13/MEIKIN | Aneuploidy and meiotic errors | Knockout in yeast or mouse oocytes to study APC/C regulation |
| AURKA | Meiotic progression defects | Overexpression or point-mutation in Xenopus oocytes |
| APC/C | Cell-cycle dysregulation and aneuploidy | Knockout or knock-in of APC/C subunits in oocytes |
| MAPK | Ectopic meiosis and cancer | Overexpression in fission yeast to induce ectopic meiosis |
Aneuploidy and infertility
Errors in the activation and progression of meiosis can lead to aneuploidy, a leading cause of miscarriage and infertility. Spo13/MEIKIN ensures a two-division meiosis by preventing APC/C(Ama1) activation at meiosis I, and its dysfunction can cause chromosome missegregation. RAB7-mediated mitophagy is required for oocyte quality control during ovarian aging, and its impairment is associated with declining oocyte quality.
Ovarian aging and reproductive decline
Ovarian aging is characterized by a decline in oocyte quality, partly due to defective mitophagy and meiotic errors. RAB7 activity is required for the regulation of mitophagy in oocyte meiosis, suggesting that targeting this pathway could mitigate age-related fertility decline.
Ectopic meiotic activation in cancer
Ectopic activation of meiosis can occur in cancer cells, contributing to genomic instability and tumor heterogeneity. The pheromone-responsive MAP kinase pathway in fission yeast drives haploid cells to undergo ectopic meiosis, providing a model for understanding how meiotic programs can be inappropriately activated.
From activation of meiosis-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is gene X required for meiotic entry? | CRISPR knockout in yeast or mouse germ cells |
| Does a specific mutation in gene Y affect meiotic activation? | Point mutation knock-in using CRISPR |
| How does tagging gene Z affect its localization during meiosis? | Tagged knock-in with fluorescent protein |
| Does overexpression of gene W drive ectopic meiosis? | Overexpression in fission yeast or oocytes |
| What is the role of RAB7 in oocyte mitophagy? | Knockout or point-mutation in mouse oocytes |
| How does Aurora-A activation timing affect meiosis I-II transition? | Overexpression or point mutation in Xenopus oocytes |
How to Study the activation of meiosis Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Dynamic localization and timing of meiotic proteins | Tracking Aurora-A activation in Xenopus oocytes |
| Phosphoproteomics | Kinase substrate phosphorylation | Identifying MAP kinase targets during ectopic meiosis |
| RNA-seq | Transcriptional changes during meiotic entry | Defining Ume6-dependent early meiotic genes |
| CRISPR knockout screen | Gene requirement for meiotic activation | Discovering novel meiotic regulators |
| CRISPR activation screen | Gain-of-function effects on meiotic entry | Inducing ectopic meiosis in non-germline cells |
| Mitophagy assays | Autophagic flux and mitochondrial quality | Assessing RAB7 function in oocyte quality control |
| Spindle checkpoint assays | Chromosome segregation fidelity | Studying Spo13/MEIKIN in aneuploidy |
| Egg activation assays | Calcium signaling and meiotic resumption | Investigating fertilization-induced meiotic completion |
Live-cell imaging of meiotic progression
Live-cell imaging using fluorescently tagged proteins allows researchers to track meiotic entry, spindle formation, and chromosome segregation in real time. This method is particularly useful for studying the dynamic activation of kinases such as Aurora-A during the meiosis I to meiosis II transition.
Phosphoproteomics and kinase profiling
Phosphoproteomics can identify substrates of kinases activated during meiotic entry, such as MAP kinase and Aurora-A. This approach reveals signaling networks that drive meiotic activation and progression.
Transcriptomics of meiotic commitment
RNA-seq and related transcriptomic methods are used to profile gene expression changes during the transition from inactive to active meiosis. In yeast, this has been instrumental in defining the Ume6 regulon and early meiosis-specific genes.
Functional genomics with CRISPR screens
CRISPR knockout and activation screens enable systematic identification of genes required for meiotic activation. These screens can be performed in haploid yeast or mammalian germline cells to uncover novel regulators.
How CRISPR Can Be Used to Study GO:0090427 activation of meiosis
Knockout
CRISPR knockout of candidate genes such as UME6, SPO13/MEIKIN, or RAB7 allows researchers to test their requirement for activation of meiosis. For example, knocking out SPO13/MEIKIN in yeast or mouse oocytes reveals its role in preventing APC/C(Ama1) activation at meiosis I.
Point Mutation
Point mutations can be introduced to dissect specific domains or phosphorylation sites in meiotic regulators. For instance, mutating Aurora-A phosphorylation sites can reveal their role in the biphasic activation during meiosis I-II transition. Similarly, point mutations in RAB7 can separate its mitophagy function from other roles.
Knock-in
Knock-in of fluorescent tags or reporter cassettes enables visualization of meiotic proteins in live cells. Tagging endogenous Ume6 or Spo13/MEIKIN allows tracking of their localization and dynamics during meiotic activation.
Overexpression
Overexpression of meiotic activators such as MAP kinase or Aurora-A can drive ectopic meiosis or accelerate meiotic entry. This approach is useful for studying gain-of-function effects and identifying downstream targets.
How EDITGENE Supports activation of meiosis Research
Researchers studying activation of meiosis-related genes often need to determine whether a candidate gene is causally involved in meiotic entry, progression, or quality control. EDITGENE provides comprehensive CRISPR-based services to generate knockout, point-mutation, knock-in, and overexpression cell models, as well as CRISPR library screening and bioinformatics support, enabling rigorous functional validation of meiotic regulators.
Contact EDITGENE today to design your custom CRISPR model for activation of meiosis research.
Frequently Asked Questions About activation of meiosis
What is activation of meiosis (GO:0090427)?
Activation of meiosis is any process that starts the inactive process of meiosis, committing a cell to the specialized two-division program that produces haploid gametes.
What genes are involved in activation of meiosis?
Key genes include UME6, SPO13/MEIKIN, AURKA, APC/C subunits, MAPK, and RAB7, which regulate transcriptional, signaling, and quality-control steps.
How is activation of meiosis regulated?
It is regulated by transcriptional reprogramming (e.g., Ume6), kinase signaling (e.g., MAP kinase, Aurora-A), APC/C control, and mitophagy.
Why is activation of meiosis important for fertility?
Proper activation ensures accurate chromosome segregation and gamete quality; defects lead to aneuploidy and infertility.
What diseases are linked to defects in activation of meiosis?
Aneuploidy, miscarriage, ovarian aging, and certain cancers have been linked to meiotic activation defects.
What model organisms are used to study activation of meiosis?
Saccharomyces cerevisiae, Schizosaccharomyces pombe, Xenopus oocytes, and mouse oocytes are commonly used.
How can CRISPR help study activation of meiosis?
CRISPR knockout, point mutation, knock-in, and overexpression enable causal testing of candidate genes in meiotic activation.
What methods are used to study activation of meiosis?
Live-cell imaging, phosphoproteomics, RNA-seq, and CRISPR screens are widely used.
What is the role of RAB7 in meiosis?
RAB7 activity is required for mitophagy regulation in oocyte meiosis and oocyte quality control during ovarian aging.
How does Spo13/MEIKIN affect meiosis?
Spo13/MEIKIN ensures a two-division meiosis by preventing activation of APC/C(Ama1) at meiosis I.
Conclusion
Activation of meiosis (GO:0090427) is a fundamental biological process that triggers the specialized two-division program of gametogenesis. Its regulation involves transcriptional, signaling, and cell-cycle mechanisms that are conserved across eukaryotes. Dysregulation of this process contributes to aneuploidy, infertility, and ovarian aging, making it a critical area of reproductive and cancer research. CRISPR-based models and functional genomics approaches are essential for dissecting the molecular players and translating these findings into clinical applications.
References
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- 2. Rojas J et al.. 2023. Spo13/MEIKIN ensures a Two-Division meiosis by preventing the activation of APC/C(Ama1) at meiosis I.. EMBO J 42(20):e114288 PMID: 37728253
- 3. Raithatha SA et al.. 2021. Ume6 Acts as a Stable Platform To Coordinate Repression and Activation of Early Meiosis-Specific Genes in Saccharomyces cerevisiae.. Mol Cell Biol 41(7):e0037820 PMID: 33941619
- 4. Machaty Z et al.. 2017. Egg Activation at Fertilization.. Adv Exp Med Biol 953:1-47 PMID: 27975269
- 5. Taieb FE et al.. 2001. Activation of the anaphase-promoting complex and degradation of cyclin B is not required for progression from Meiosis I to II in Xenopus oocytes.. Curr Biol 11(7):508-13 PMID: 11413001
- 6. Russo GL et al.. 1998. Ins and outs of meiosis in ascidians.. Semin Cell Dev Biol 9(5):559-67 PMID: 9835644
- 7. Yamamoto TG et al.. 2004. Activation of the pheromone-responsive MAP kinase drives haploid cells to undergo ectopic meiosis with normal telomere clustering and sister chromatid segregation in fission yeast.. J Cell Sci 117(Pt 17):3875-86 PMID: 15265989
- 8. Ma C et al.. 2003. Biphasic activation of Aurora-A kinase during the meiosis I- meiosis II transition in Xenopus oocytes.. Mol Cell Biol 23(5):1703-16 PMID: 12588989
