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Published on: June 16, 2023
ER-PM Contacts Restrict Exocytic Sites for Polarized Morphogenesis
Amanda Yunn Ee Ng1, Annabel Qi En Ng1, Dan Zhang1
1Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Singapore.
Endoplasmic reticulum (ER)-plasma membrane (PM) contacts restrict exocytosis sites, maintaining fission yeast cell shape. Disrupting these contacts leads to delocalized exocytosis and abnormal cell morphology.
Area of Science:
- Cell biology
- Biophysics
- Molecular biology
Background:
- Polarized cell morphogenesis relies on spatial control of exocytosis.
- In fission yeast, exocytic vesicles are transported by myosin V motors to growing cell ends.
- Actomyosin-based vesicle delivery is not essential for fission yeast's polarized secretion and shape.
Purpose of the Study:
- Investigate the role of endoplasmic reticulum (ER)-plasma membrane (PM) contacts in restricting exocytic sites.
- Determine how ER-PM contacts influence polarized fission yeast morphogenesis.
- Identify novel mechanisms for spatial confinement of exocytosis.
Main Methods:
- Utilized fission yeast as a model organism.
- Generated and analyzed fission yeast mutants deficient in ER-PM contacts and actomyosin-based vesicle transport.
- Artificially manipulated ER-PM contact strength and extent in wild-type and mutant cells.
- Observed effects of ER-PM contacts on exocytic site localization and cell shape.
Main Results:
- Fission yeast cells lacking ER-PM contacts and actomyosin-based transport exhibited globular shapes due to delocalized exocytosis.
- Exocytosis and ER-PM contact formation were found to be spatially incompatible.
- Extensive ER-PM junctions at the lateral cell cortex inhibited PM exocytic vesicle tethering, reducing growth potential at cell sides.
Conclusions:
- ER-plasma membrane contacts serve as a novel morphogenetic module in fission yeast.
- These contacts limit exocytosis to growing cell tips, ensuring proper cell shape.
- A similar ER-PM contact-mediated mechanism may regulate cell morphogenesis in other cell types.
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