Organized microtubule arrays are essential for cell division, cell migration, trafficking, and cell morphogenesis. Proliferating and migrating animal cells feature radial arrays of centrosome-anchored microtubules, whereas differentiated animal cells and all plant cells can organize their microtubules without centrosomes. These noncentrosomal microtubule arrays are involved in vital cellular functions, however the mechanisms involved in microtubule organization in the absence of centrosomes are not well understood. Consistent with the essential functions of organized microtubule arrays, plant and animal cells widely utilize evolutionarily conserved molecules to regulate microtubule organization. A ring-like microtubule array is organized at the cortex of plant cells entering mitosis. This microtubule array, the preprophase band (PPB), is important for spindle guidance and positioning of the cell division plane. A complex of evolutionarily conserved proteins that include TON1 and TRM proteins, which are homologous to the human microtubule-anchoring centrosomal proteins FOP and CAP350, and the protein phosphatase PP2A drives the organization of the PPB. The function of TON1 proteins in the complex of TON1/TRM/Ton2/PP2a proteins promoting PPB array formation will be tested. Understanding the mechanism of PPB microtubule array organization will uncover common mechanisms and specific modifications driving the formation of centrosomal and noncentrosomal arrays.
Relevance to public health: The proposed project is focused on understanding the mechanisms of microtubule cytoskeleton organization. Organized microtubule arrays are crucial for faithful chromosome segregation and cell differentiation, safeguarding cells against aneuploidy and cancer. The proposed study will contribute to better understanding of human diseases caused by the dysregulation of the microtubule cytoskeleton, including cancer, neuronal migration disorders leading to brain malformations, and human ciliary diseases.
