QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 17, Issue 10, 4494-4512, October 2006

This Article Full Text Full Text (PDF) Supplemental Material All Versions of this Article: E06-03-0215v1 17/10/4494    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Helfer, H. Articles by Gladfelter, A. S. Search for Related Content PubMed PubMed Citation Articles by Helfer, H. Articles by Gladfelter, A. S.

AgSwe1p Regulates Mitosis in Response to Morphogenesis and Nutrients in Multinucleated Ashbya gossypii Cells

Hanspeter Helfer^*, and Amy S. Gladfelter^*,

*University of Basel Biozentrum, Molecular Microbiology, 4056 Basel, Switzerland; and Department of Biology, Dartmouth College, Hanover, NH 03755

Submitted March 21, 2006; Revised July 12, 2006; Accepted July 31, 2006
Monitoring Editor: Kerry Bloom

Nuclei in the filamentous, multinucleated fungus Ashbya gossypii divide asynchronously. We have investigated what internal and external signals spatially direct mitosis within these hyphal cells. Mitoses are most common near cortical septin rings found at growing tips and branchpoints. In septin mutants, mitoses are no longer concentrated at branchpoints, suggesting that the septin rings function to locally promote mitosis near new branches. Similarly, cells lacking AgSwe1p kinase (a Wee1 homologue), AgHsl1p (a Nim1-related kinase), and AgMih1p phosphatase (the Cdc25 homologue that likely counteracts AgSwe1p activity) also have mitoses distributed randomly in the hyphae as opposed to at branchpoints. Surprisingly, however, no phosphorylation of the CDK tyrosine 18 residue, the conserved substrate of Swe1p kinases, was detected in normally growing cells. In contrast, abundant CDK tyrosine phosphorylation was apparent in starving cells, resulting in diminished nuclear density. This starvation-induced CDK phosphorylation is AgSwe1p dependent, and overexpressed AgSwe1p is sufficient to delay nuclei even in rich nutrient conditions. In starving cells lacking septins or AgSwe1p negative regulators, the nuclear density is further diminished compared with wild type. We have generated a model in which AgSwe1p may regulate mitosis in response to cell intrinsic morphogenesis cues and external nutrient availability in multinucleated cells.

This article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E06-03-0215) on August 9, 2006.

Address correspondence to: Amy Susanne Gladfelter (Amy.Gladfelter{at}Dartmouth.edu)

This article has been cited by other articles:

				S. D. Harris Branching of fungal hyphae: regulation, mechanisms and comparison with other branching systems Mycologia, November 1, 2008; 100(6): 823 - 832. [Abstract] [Full Text] [PDF]

				K. R. Finley, K. J. Bouchonville, A. Quick, and J. Berman Dynein-dependent nuclear dynamics affect morphogenesis in Candida albicans by means of the Bub2p spindle checkpoint J. Cell Sci., February 15, 2008; 121(4): 466 - 476. [Abstract] [Full Text] [PDF]