Mechanisms and dynamics of interkinetic nuclear migration (IKNM) in pseudostratified epithelia

Yuichiro Nakajima

The control of tissue growth, with the control of cell proliferation at its core, is a key problem in developmental biology. We have shown that IKNM-like cell behavior, a mitotic movement of the nucleus to the apical epithelial surface, is an evolutionally conserved feature of cell division in proliferating epithelia. Presently, we are investigating the mechanisms of spindle formation and alignment within the epithelium, especially focusing on centrosome dynamics. We are using a combination of live imaging and genetics to gain new insight into the regulation of epithelial cell division.

Mitosis in the epithelial context: interkinetic nuclear migration

Emily Jo Meyer

In epithelia, a dramatic illustration of the integration between epithelial morphogenesis and cell proliferation is interkinetic nuclear migration (IKNM). IKNM is widely considered a hallmark of pseudostratified vertebrate neuroepithelia, and prior investigations have proposed both actomyosin- and microtubule-dependent mechanisms for apical localization of the mitotic nucleus. Using comparative functional analysis in arthropod and cnidarian systems (Drosophila melanogaster and Nematostella vectensis), we have shown that actomyosin-dependent IKNM is likely to be a general feature of mitosis in pseudostratified epithelia throughout Eumetazoa.  Our studies also suggest a mechanistic link between IKNM and the fundamental process of mitotic cell rounding. We are currently investigating centrosome dynamics and spindle positioning during IKNM as well as throughout the progressive stages of mitosis.