Inositol 1, 4, 5-trisphosphate receptor is required for spindle assembly in Xenopus oocytes
Ruizhen Li1, Yanping Ren1,2, Guolong Mo1,3
1Ottawa Hospital Research Institute, The Ottawa Hospital-General Campus, Ottawa, ON K1H 8L6, Canada.
Molecular Biology of the Cell
|September 21, 2022
Summary
Intracellular calcium signaling, specifically involving the inositol-1,4,5-trisphosphate receptor (IP3R), is crucial for meiotic spindle assembly in Xenopus oocytes. Disruption of IP3R function prevents proper spindle formation during meiosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Reproductive Biology
Background:
- Calcium signaling's role in cell division (meiosis and mitosis) remains controversial.
- Previous work suggested calcium nanodomains are vital for spindle microtubule stability in Xenopus oocytes.
- The specific calcium channels involved in meiotic spindle assembly were not fully understood.
Purpose of the Study:
- To investigate the function of the inositol-1,4,5-trisphosphate receptor (IP3R) in meiotic spindle assembly.
- To determine if IP3R-mediated calcium release is essential for forming functional meiotic spindles in Xenopus oocytes.
Main Methods:
- Utilized Trim21-mediated depletion to remove IP3R from Xenopus oocytes.
- Developed and employed a cell-free spindle assembly assay using aspirated oocyte cytoplasm.
- Observed spindle formation and stability under conditions of IP3R depletion and calcium signaling disruption.
Main Results:
- Xenopus oocytes depleted of IP3R failed to assemble meiotic spindles and emit the first polar body.
- In cell-free extracts, assembled spindles were associated with endoplasmic reticulum (ER) membranes enriched with IP3R.
- Disrupting ER organization or calcium signaling led to rapid spindle disassembly in cell-free systems.
Conclusions:
- Intracellular calcium signaling mediated by IP3R is essential for meiotic spindle assembly in Xenopus oocytes.
- IP3R channels on the ER play a critical role in regulating calcium dynamics necessary for spindle formation.
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