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MERIT Award Recipient: Joan Massague, PhD
The basic functions of an animal cell -- its metabolism, proliferation,
differentiation, integration into the tissue structure, and eventual death --
are controlled by a dense network of protein growth factor signals. The
transforming growth factor-β (TGF-β) family of growth factors is particularly
prominent among this type of signal. TGF-β fosters tissue formation and growth
during embryonic development in organisms as diverse as worms, fruit flies, and
humans. In the adult, however, TGF-β delivers anti-proliferative and cell death
signals. These responses help maintain normal tissue structure and function,
and their loss contributes to tumor development: cancer cells that evade
TGF-β-mediated growth inhibition may then use TGF-β to promote their own
proliferative, invasive, and metastatic behavior. This project is devoted to
defining the mechanisms by which TGF-β and related factors trigger regulatory
signals in normal cells but fail to do so in cancer cells.
During the first decade of work on this project, we set the foundation for
identifying the basic components of the TGF-β intracellular signaling pathway,
including the Smad family of proteins that is essential for transmitting TGF-β
signals. This goal was accomplished during the second decade of this project,
supported by a MERIT award. In its third decade, supported by a renewed MERIT
award, this project is devoted to defining the integration of the TGF-β/Smad
pathway in the complex and diverse signaling networks of the cell, and the
corruption of TGF-β signaling in cancer. We will address this general problem
in several complementary ways by focusing on Smad proteins and their partners
as nodes for signal integration. We will investigate how diverse signals
control Smad function and degradation. Having identified key partners of Smads
in the mediation of TGF-β anti-proliferative effects, we will determine their
roles as modifiers of the cellular response to TGF-β. Further, we will
investigate the biological significance of diverse cellular functions (tissue
formation, metastasis, cell cycle arrest, negative feedback) that are
controlled by intracellular mediators of TGF-β-triggered signals. We will also
seek to identify new central components and regulators of the TGF-β/Smad pathway
through the use of novel chemical, biochemical, and functional proteomics
approaches. Through this work, we wish to furnish the field with a better
understanding of the role of the TGF-β/Smad pathway in physiology and an
improved ability to manage this pathway in tumor progression, metastasis and
other disorders.
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