Stem Cell Biology

Stem Cell Biology

Stem cells offer tremendous potential to develop treatments for numerous diseases. Using Proteomics we are attempting to further our understanding of the basic cellular process underlying stem cell self-renewal, maintenance and differentiation.

 

The focus of our research is to understand the molecular and cellular factors involved in regulating various aspects of the embryonic and hematopoietic stem cell. The underlying rationale for our studies is that various aspects of the stem cell regulation is controlled by a complement of proteins and their post translationally modified forms.

Hematopoietic stem cells

Our interest in the hematopoietic stem cell (HSC) has tied in nicely with the laboratory’s primary interest in leukaemia. Shotgun phosphoproteomic analysis of hematopoietic progenitor cells treated with the chemotactic agent Stromal Derived Factor-1 (CXCL12) and / or the Rac1/2 inhibitor NSC23766 demonstrated regulation of a novel phosphorylation event on PTPRC. The phosphoserine event on PTPRC has been demonstrated to regulate the activity of PTPRC which subsequently has been demonstrated to activate SRC in HSC chemotaxis. Also interestingly this pathway has been shown to be involved in regulating Thoc5 and its function in oncogenic tyrosine kinase regulation of mRNA transport.

Embryonic stem cells

Primarily our research is with murine embryonic stem (ES) cells, however recently this has expanded to human stem cells through collaborations with the Ihor Lemischka and Saghi Gaffiri laboratories at Mt. Sinai (New York). Our research has been varied; shotgun style discovery proteomic techniques have successfully identified and relatively quantified 1000s of proteins in ES cells differentiating along a mesodermal route. Discovery proteomics has also been successfully utilised in identifying and relatively quantifying 100s of phosphorylation events in the differentiating stem cell. Such molecular "signatures" provide the necessary tools for regulation of the ES cell. Through the aforementioned collaborative work with the Lemischka lab, we provided the proteomic arm of a systems biology analysis of ES cells. Molecular regulation of ES cell fate involves a coordinated interaction between epigenetic, transcriptional and translational mechanisms. It was demonstrated that global changes in histone acetylation, chromatin-bound RNA polymerase II, messenger RNA (mRNA), and nuclear protein levels were measured after downregulation of key pluripotency regulators. These strategies have provided the first in-depth view of how a cell-fate decision actually occurs at the transcriptional, post-transcriptional, translational, and post-translational levels. More directed analysis has also demonstrated differences in p53 phosphorylation status in Aurka knock down cells.