Assistant Professor

* Assistant Professor
* M.S. Moscow Institute for Physics and Technology, Moscow (Russia) 1991
* Ph.D. Engelhardt Institute for Molecular Biology, Moscow (Russia) 1996

Honors:

Robert T. McCluskey, M.D., Yale Scholar Award, 2007

Research Interests:

* Molecular control of cell fate decisions in embryonic and somatic stem cells
* Lineage specification during early mouse development
* Functional genomics
* Systems biology

Current Research:

Embryonic and adult stem cells hold great promise for regenerative medicine, tissue repair and gene therapy. Embryonic stem cells represent a transient cell population that exist during embryonic development and can give rise to all cell types present in an adult, while adult (somatic) stem cells are permanent cell populations dedicated to homeostatic production of mature cells in tissues such as blood, skin and gut. All stem cells must be able to balance self-renewal versus differentiation, regulate proliferation and cell death.

Our long-term goal is to understand how cell-fate decisions in stem cells are regulated at the molecular level. We employ a broad-based strategy that integrates molecular, cellular and organismal approaches. Our research efforts are divided between the two stem cell systems:

Embryonic stem cells:

We have recently developed a functional genomics approach to identify genetic mechanisms that control self-renewal in embryonic stem cells. This approach utilizes short hairpin RNA (shRNA) loss-of-function techniques to downregulate a set of gene products whose expression patterns suggest self-renewal regulatory functions. We have applied this approach to a selected panel of candidate regulators and demonstrated that in addition to previously identified Nanog, Oct4 and Sox2 several other genes are required for efficient self-renewal of ES cells in vitro (Ivanova et al., Nature 2006). We are currently extending this screening strategy to genome-scale shRNA libraries.

The ongoing projects include: 1) Large-scale loss-of-function analyses to identify gene products that are required for self-renewal of mouse and human ES cells, and for commitment to specific lineages, 2) In-depth characterization of previously identified regulators of self-renewal and differentiation, 3) Computational modeling of lineage commitment.

Hematopoietic stem cells:

Hematopoiesis is organized as a hierarchy of cells of with decreasing self-renewal and differentiation potential. Long-term HSC, the most primitive cell in this hierarchy, can give rise to all blood lineages and has unlimited capacity to self-renew. LT-HSC produces short-term HSC which are still multipotent but are limited in self-renewal capacity. ST-HSC differentiates further into lineage-committed progenitor cells which are responsible for the large-scale production of mature blood cells. We have chosen global gene expression analysis in primary cells followed by functional characterization of candidate gene products as an approach towards the comprehensive identification of HSC regulatory mechanisms.

To date we have performed transcriptional profiling of fetal and adult HSC using microarray-based technologies and have defined sets of genes that are specifically expressed in HSC but not in more differentiated compartments of the hematopoietic hierarchy. Some of these candidate genes are likely to function as key regulators of self-renewal and differentiation (Ivanova, Science 2002). We are currently focusing on two projects: 1) Single-cell gene expression analysis to define functional subsets within HSC and 2) Functional analyses of candidate genes to identify gene-products that are necessary and/or sufficient for self-renewal of HSC both in vivo and in vitro.