Tao Lin and Jasneet Kaur Lab Advisor: Dr. Edward Bonder Teaching Assistant: Susan Seipel

Is there a correlation between spindle orientation in mitotic cells and the contracted cell shape caused by the GTPase protein, RhoA? RhoA mDia Rho kinase Myosin phosphatase LimK Cofilin Actin-myosin filament stabilization MLC-p MLC Actin polymerization Unbranched filaments Stress fibers Actin-myosin contractility (cell rounding) EB1/APC Microtubule growth and stabilization

Spread, control cell Contracted cell with constitutively active RhoA Note: These images have been generated through a 90 degree vertical projection of z-series images

Y27632 treatment Y27632 inhibits Rho kinase which causes actin-myosin contractility leading to rounded cell shape. Different concentrations of Y27632 used  0 μ M, 1.0 μ M, 1.5 μ M, 2.0 μ M 2.5 μ M, 5.0 μ M, 10.0 μ M High concentrations of Y27632 allow the cell shape to return to normal Goal: What is the point where cell shape remains contracted but the spindle orientation returns to normal? –Will show that the spindle misorientation is not a direct effect of contracted shape caused by RhoA, and thus, is caused by a different aspect of the RhoA signaling pathway.