Our Research:

Cells, like whole organisms, have an incredible diversity of form, but unlike whole organisms, we know significantly less about how cells develop.  Patterning at the cellular level allows cells to carry out specialized functions. We are studying how the microtubule cytoskeleton is patterned during development and how this specific patterning allows for the diversification of cellular form and function.

Microtubules do not just form randomly within the cytoplasm, but instead are arranged at specific sites called microtubule organizing centers (MTOCs). The vast majority of what is known about MTOCs comes from work on the centrosome. The centrosome is a non-membrane bound organelle composed of two centrioles surrounded by a cloud of pericentriolar material (PCM). Microtubules grow from microtubule nucleating proteins embedded within the PCM.

In many types of differentiated cells such as neurons, myotubes, and epithelial cells, microtubules are arranged at sites other than the centrosome. We study cells in the nematode C. elegans such as embryonic intestinal cells, in which microtubules (red) are arranged at the apical membrane and not at nearby centrosomes (green). Because centrosomes are the MTOCs in mitotic cells, MTOC function must be reassigned to the membrane in these cells following mitosis.

Using live cell imaging during the development of epithelial cells, we found that a nascent MTOC appears to be transferred from the centrosome to the membrane as the cells are polarizing. Microtubule nucleating proteins such as γ-tubulin appear as a "plume" near the centrosome before associating with the membrane. Thus, MTOC function appears to be handed-off from the centrosome following mitosis through a physical transfer of microtubule nucleating proteins such as γ-tubulin (green).

In the Feldman Lab, we are interested in understanding the mechanisms underlying cell patterning. In particular, we are taking a genetic, biochemical, and live imaging approach to pursue two main projects related to microtubule organization using the model organism C. elegans:

Project 1: How is a new MTOC formed?
Project 2: How is an MTOC turned OFF?