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PhD Transfer Exam – Yunyun Huang (Winklbauer lab)
May 9, 2016 @ 2:10 pm - 3:10 pm
PhD Transfer Exam
Monday May 9th, 2:10 pm – Ramsay Wright Building, Rm. RW 432
Yunyun Huang (Winklbauer lab)
“Characterizing the Roles of Prickle and Dishevelled in Regulating Cell Adhesion Processes during Xenopus Gastrulation“
Abstract
In Xenopus embryos, mesodermal cells undergo radial intercalation and migrate along the inner surface of the blastocoel roof while remaining separate from the ectoderm. These gastrulation movements require continuous cell-cell adhesion as well as repeated attachment and detachment, the regulation of which has yet to be fully elucidated. Previous work has shown participation of planar cell polarity (PCP) signalling proteins in regulating cell adhesion and separation. Using Prickle1 (Pk1) and Dishevelled2 (Dvl2) as two examples, I will study the role of PCP components in local polarized regulation of cell attachment and detachment during mesodermal cell directional migration. My preliminary data has shown a correlation of Pk1 and Dvl2 with cell detachment behaviour at the rear and lateral sides, respectively. I also found that Pk1 and Dvl2 modulate cell adhesion strength and cortical contractility through up- and downregulation of cortical F‑actin content. My hypothesis is that Pk1 accumulates at the cell trailing edge, and locally up-regulates cortical F-actin to increase contractility of the retraction fibre. I also propose that the diffuse form of Dvl2 promotes lateral cell-cell adhesion by down-regulating cell cortex contractility, whereas Dvl puncta stabilizes distinct lateral adhesion sites between cells. During directional migration, I propose that mesoderm cells are polarized cell-autonomously with respect to Pk1 and Dvl2 puncta localization, and become oriented by ectoderm secreted PDGF-A signalling. Using both in vivo explant systems and in vitro cell spreading assays, I will help clarify how the local, polarized regulation of cell attachment/ detachment contributes to overall cell adhesion and directional migration.
Ramsay Wright is a wheelchair accessible building.