Dr. Ray Keller

Cellular Mechanisms of Gastrulation

Toshiyasu Goto,Lance Davidson,Makoto Asashima, and Ray Keller 2007. Planar Cell Polarity Genes Regulate Polarized Extracellular Matrix Deposition during Frog Gastrulation Current Biology, Vol. 15, 787–793.

Question 1

Briefly tell us a bit about yourself, your career path over the years, and specifically what led you to begin working on gastrulation.

Michael Barresi

Question 2

Could you describe the difference between indirect and direct involvement of the PCP pathway in organizing the extracellular matrix? What is an example of indirect?

Sanna Cahn

Question 3

Your results suggest that the PCP pathway has two functions, the first of which is for the directed polarized assembly of fibronectin fibrils along tissue surrounding the mesoderm. How exactly do the PCP genes accomplish this? Do the fibronectin fibrils rely on a protein gradient of PCP gene products or is there some other intermediate signal that helps regulate fibril assembly?

Susy Ramos

Question 4

In your study you mention that Xpk may locally activate the PCP complex in response to radial tissue polarity cues already present in the embryo. What are these cues and how do they contribute to PCP activation?

Cecilia Flores

Question 5

You suggest a two-step model for the function of PCP during cell polarization; the first step is to polarize the mesodermal cells and then to polarize the cells mediolaterally resulting in MIB behavior and ultimately convergent extension. Please briefly describe this first step, and comment on whether any non-PCP models have been proposed and tested to regulate cell polarization?

Elizabeth Deschene

Question 6

What interaction takes place with the fibronectin to make it go to particular areas of the cell, and how might this influence directed extension of lamellipodia in the right direction?

Trina Campbell

Question 7

We learned in class about the role of Calcium pulses from the midline during convergent extension. What initiates the midline cells to start releasing calcium waves and how does this cause convergence and extension?

Alison Meyers

Question 8

Currently in your opinion what are the most pressing questions in the field of gastrulation, and what steps is your lab taking to address those questions?

Michael Barresi