Our laboratory is focused on understanding how chromosomes and the mitotic spindle are properly aligned and positioned during cell division. Correct placement of the mitotic spindle is critical in ensuring genomic constancy, as well as in segregating asymmetric protein determinants to different cells during development. The yeast S. cerevisiae is particularly amenable to this study in the wealth of knowledge available on establishment of asymmetry. We utilize both cytological and genetic approaches toward understanding the mechanisms of nuclear and spindle positioning, and determining how spindle movements are coordinated with asymmetric protein localization, polarity establishment and cell separation.

Spatial information must be transmitted to the spindle via microtubules and studies on how this information is transmitted will entail dissecting the role of individual microtubule-based motor proteins and microtubule dynamic instability. Our focus concerns the spatial and temporal regulation of microtubules, dynein and polarity establishment proteins whose mutant phenotypes suggest they are directly involved in this process. Although asymmetric divisions in yeast represent a rather specialized form of cytokinesis and cleavage plane determination, all eukaryotic systems share common elements such as microtubules, microtubule motor proteins, actin and polarity establishment mechanisms. Thus, while yeast and animals may differ in the flow of spatial information, both involve cytoskeleton mediated interactions between the cell cortex and the microtubules and motors emanating from the nucleus/mitotic apparatus. Insights into the mechanism of nuclear migration in budding yeast should have broad applications towards understanding this process in a wide variety of organisms.