Positioning of cell growth and division after osmotic stress requires a map kinase pathway
Article first published online: 29 JAN 2004
Copyright © 1994 John Wiley & Sons Ltd.
Volume 10, Issue 4, pages 425–439, April 1994
How to Cite
Brewster, J. L. and Gustin, M. C. (1994), Positioning of cell growth and division after osmotic stress requires a map kinase pathway. Yeast, 10: 425–439. doi: 10.1002/yea.320100402
- Issue published online: 29 JAN 2004
- Article first published online: 29 JAN 2004
- Manuscript Accepted: 12 OCT 1993
- Manuscript Received: 21 MAY 1993
- Saccharomyces cerevisiae;
- MAP kinase;
- osmotic stress;
- cell division;
- actin cytoskeleton
The yeast Saccharomyces cerevisiae has a genetic program for selecting and assembling a bud site on the cell cortex. Yeast cells confine their growth to the emerging bud, a process directed by cortical patches of actin filaments within the bud. We have investigated how cells regulate budding in response to osmotic stress, focusing on the role of the high osmolarity glycerol response (HOG) pathway in mediating this regulation. An increase in external osmolarity induces a growth arrest in which actin filaments are lost from the bud. This is followed by a recovery phase in which actin filaments return to their original locations and growth of the original bud resumes. After recovery from osmotic stress, haploid cells retain an axial pattern of bud site selection while diploids change their bipolar budding pattern to an increased bias for forming a bud on the opposite side of the cell from the previous bud site. Mutants lacking the mitogen-activated protein (MAP) kinase encoded by HOG1 or the MAP kinase kinase encoded by PBS2 (previously HOG4) show a similar growth arrest after osmotic stress. However, in the recovery phase, the mutant cells (a) do not restart growth of the original bud but rather start a new bud, (b) fail to restore actin filaments to the original bud but move them to the new one, and (c) show a more random budding pattern. These defects are elicited by an increase in osmolarity and not by other environmental stresses (e.g., heat shock or change in carbon source) that also cause a temporary growth arrest and shift in actin distribution. Thus, the HOG pathway is required for repositioning of the actin cytoskeleton and the normal spatial patterns of cell growth after recovery from osmotic stress.