January 24 2006
9:30 LSB 2320

Abstract:

Stem-cell homeostasis is a dynamic process that results from active orchestration of the spatio-temporal patterns of gene expression, and of cellular behavior, by cell-cell communication. The challenge is not only to identify molecular components that mediate stem-cell homeostasis, but also to understand how cells interpret a combination of local cues and global signals to adjust their division behavior and gene expression patterns, thereby maintaining a functional stem-cell niche.

I utilize shoot apical meristems (SAM) of Arabidopsis thaliana as a model system to study stem-cell homeostasis. SAMs of flowering plants have a remarkable ability to maintain a stable pool of stem-cells despite constant diversion of cells to differentiation pathways. Conventional genetic analysis has yielded a molecular framework that mediates stem-cell homeostasis. However, analysis based on terminal phenotypes of mutants is inadequate to define the function of individual genes in the network of interacting cells. Resolving the function of individual genes in an interacting network would involve creating transient perturbations in gene activities by turning them off/on in a living, wild-type SAM and following in real time the changes in the organization of the SAM. I have developed methods to transiently alter gene activities in wild type SAMs and to record real-time changes in cell identities and cell behavior.

A brief summary of novel mechanistic insights into the process of stem-cell maintenance, mediated by CLAVATA -WUSCHEL regulatory network will be presented. I will also discuss a conceptual framework for future experiments to address questions such as; how do global cues provided by plant hormones, light and temperature interact with local cell-cell communication machinery to maintain a functional stem-cell niche? My talk will also highlight the importance of transient intervention and in-vivo imaging in conducting hypothesis-driven research, thereby deciphering cellular and molecular networks that function in stem cell homeostasis.