Studies in fission yeast on mechanisms of cell division site placement.

One fundamental problem in cytokinesis is how the plane of cell division is established. In this review, we describe our studies on searching for "signals" that position the cell division plane, using fission yeast Schizosaccharomyces pombe. First, we take a genetic approach to determine how the nucleus may position the contractile ring in fission yeast. mid1p appears to link the position of the ring with the nuclear position, as it is required for proper placement of the contractile ring and is localized in a band at the cell surface overlying the nucleus. Second, we study how microtubules may function in the establishment of cell polarity at the cell tips. tea1p may be deposited on the cell surface by microtubules and function to recruit proteins involved in making actin structures. These studies suggest how microtubules may direct the assembly of the contractile ring in animal cells.