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Magnuson, Mark A., Department of Molecular Physiology and Biophysics

Mark A. Magnuson, M.D.
Earl W. Sutherland, Jr. Professor of Molecular Physiology and Biophysics
Professor of Cell and Developmental Biology, and of Medicine
Director, Center for Stem Cell Biology
Vanderbilt University School of Medicine
9465 MRB-IV
615-322-7006 (office)

We utilize mouse and embryonic stem cells (ESCs) as model systems to study both the mechanisms and genes involved in cell fate specification, especially as it relates to the formation of endocrine cells.  By applying the methods of gene targeting and recombinase-mediated cassette exchange in ESCs we have generated animals in which key genes that control cell fate decisions are tagged with different colored fluorescent proteins (FPs).  These alleles enable us to see exactly when and where particular genes are expressed, and then to isolate highly purified cell populations by Fluorescence Activated Cell Sorting (FACS).  RNA from these cells is then converted to cDNA and individual transcripts are quantified using Next Generation Sequencing technology.  This approach provides highly detailed, genome wide gene expression information.  By performing detailed bioinformatics analysis we anticipate gaining new insights into how endodermally-derived organs are specified.

We are also interested in understanding the mechanisms of signaling through the phosphoinositol-3-kinase (PI3K) pathway, particularly the role of Rictor, a key component of mTOR complex 2, which plays a central role in growth factor signaling.  We have found that Rictor/mTOR complex 2 is essential for maintaining a balance between the rate of cell proliferation and cell size in response to growth factor stimulation.