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Membrane traffic between secretory compartments is differentially affected during mitosis.
1Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Cell Regulation
|April 1, 1990
Summary
Cell division significantly disrupts the endoplasmic reticulum (ER)-to-Golgi pathway, blocking protein secretion. However, later secretory steps, like trans-Golgi to plasma membrane transport, remain largely functional during mitosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Membrane traffic is regulated during cell division.
- Endoplasmic reticulum (ER)-to-Golgi transport is blocked in mitotic cells.
- The impact of mitosis on later secretory pathway steps is unclear.
Purpose of the Study:
- To investigate the functional characteristics of secretory pathways in mitotic mammalian cells.
- To determine the extent of disruption at different stages of the secretory pathway during mitosis.
Main Methods:
- Utilized Chinese hamster ovary cells transfected with secretory protein cDNAs.
- Employed viral membrane proteins and human growth hormone as markers.
- Assessed ER export using endoglycosidase H resistance.
- Tracked trans-Golgi to plasma membrane transport via sulfated glycosaminoglycan (GAG) chain secretion.
Main Results:
- Overall secretory pathway is nonfunctional in mitotic cells, with a major block between ER and Golgi.
- Secretion of human growth hormone reduced at least 10-fold; ER export of VSV G protein inhibited similarly.
- Trans-Golgi to plasma membrane transport of GAG chains showed only a twofold reduction in initial secretion rate during mitosis.
- GAG chain secretion extent was unaltered during mitosis.
Conclusions:
- Mitosis severely hinders ER-to-Golgi transport but has a less pronounced effect on trans-Golgi to plasma membrane transport.
- Secretory pathway transport steps are differentially affected during cell division.
- The secretory pathway is not uniformly nonfunctional during mitosis.