Endoplasmic-reticulum-mediated microtubule alignment governs cytoplasmic streaming

Area of Science:

• Cell Biology
• Developmental Biology
• Biophysics

Background:

• Cytoplasmic streaming is a fundamental cellular process observed across diverse organisms.
• The mechanism of meiotic cytoplasmic streaming (MeiCS) in Caenorhabditis elegans zygotes is not fully understood, particularly its lack of predefined polarity and occasional flow reversals.

Purpose of the Study:

• To elucidate the underlying mechanism of meiotic cytoplasmic streaming (MeiCS) in C. elegans zygotes.
• To investigate the role of the endoplasmic reticulum (ER) network in regulating cytoplasmic flow direction and self-organization.

Main Methods:

• Utilized RNA interference (RNAi) to manipulate cellular components.
• Employed advanced microscopy and image processing techniques for C. elegans zygotes.
• Developed a theoretical model to simulate and predict cytoplasmic streaming dynamics.

Main Results:

• Demonstrated that the endoplasmic reticulum (ER) network structure is essential for collective cytoplasmic flow.
• Proposed a positive-feedback model where ER transmits local microtubule-generated flow to neighboring regions.
• Showed that this mechanism leads to microtubule alignment and self-organization of collective flow, capable of emergence and reversal.

Conclusions:

• The ER network plays a critical role in self-organizing meiotic cytoplasmic streaming in C. elegans zygotes.
• A positive-feedback loop between ER and microtubules drives the collective flow, applicable even without predefined cell polarity.
• MeiCS enhances cortical granule mobility, facilitating efficient exocytosis for zygote protection against stresses.