Core mechanisms that regulate the polarity of a cell and its shape are evolutionarily conserved. Polarized cell growth, which determines cell shape, depends on a localized crosstalk between the microtubule and actin cytoskeletons and the cell membrane. Our work shows that the actin and microtubule regulator Asp1, an evolutionarily conserved Vip1 family IP6 kinase, links the actin and microtubule cytoskeletons and is essential for proper polarized growth in the fission yeast Schizosaccharomyces pombe. In addition, we have recently identified Asp1 as a molecular switch for the transition from a yeast form to cells that show invasive, hyphal-like growth. This is the first time that such a role has been described for a member of the Vip1 kinase family. The aim of this project is to understand how Asp1 and Asp1 interacting proteins regulate the switch from the yeast- to the hyphal-like invasive form.
The Asp1 kinase-only variant gives rise to cell-cell adhesion (A), increased cell-substrate adhesion (B) and invasive growth (B, bottom; C, D). Scale bars in C are 10 µm. Cells were incubated in/on rich medium for 18 hrs (A), 25 days (B) and 11 days (C). (D) shows an enlargement of the invasive cells shown in (B).