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Robert C. Piper, PhD

Contact Information:

Office: 6-532 BSB
Phone: 319-335-7842
Faculty Profile

Brief description of current research:

My lab is interested in understanding the mechanisms that govern the movement of proteins within the endosomal system. This is a fundamental process of all eukaryotic cells necessary for regulating a variety of cell surface proteins. Much of our current work is focused on  how cell surface proteins are targeted for degradation in the lysosome. Here proteins are sorted into vesicles that bud inward into the lumen of the endosome.  This budding event stands as a pivotal regulatory step in the endocytic pathway and regulates the ability of proteins to otherwise recycle back to the cell surface.  Attachment of ubiquitin confers sorting into this degradative pathway and that ubiquitin itself carries sorting information that is recognized by “ubiquitin-sorting receptors”. Currently, we are discovering and characterizing these ubiquitin-sorting receptors and determining how they are regulated.  We are also studying how the function of these sorting receptors is integrated into the formation of inward budding vesicles themselves.  Finally, we are discovering the cellular machinery that mediates recycling from endosomes back to the cell surface, a process important for maintaining high levels of particular cell surface proteins. These  trafficking processes play pivotal roles in the movement of glucose and other nutrient transporters to the plasma membrane, the activity of cell surface receptors such as the insulin-receptor, and the regulation of mTOR which is intimately tied to lysosomal activity.   Our interest protein trafficking through the endosomal system will be used discover aspects of how the endosomal system in responds to insulin and other signals that regulate growth and metabolism.

3 most influential diabetes/obesity/metabolism publications:

  • MacDonald C, Piper RC. (2017) Genetic dissection of early endosomal recycling highlights a TORC1-independent role for Rag GTPases. J Cell Biol. Oct 2;216(10):3275-3290. 
  • MacDonald C, Payne JA, Aboian M, Smith W, Katzmann DJ, Piper RC. (2015) A family of tetraspans organizes cargo for sorting into multivesicular bodies. Dev Cell. 2015 May 4;33(3):328-42. 
  • Pashkova, N, Gakhar, L., Winistorfer, SW., Sunshine, A.B., Rich, M., Dunham, M.J., Yu, L., Piper, RC. (2013)  The Yeast Alix homolog, Bro1, Functions as a Ubiquitin Receptor for Protein Sorting into Multivesicular Endosomes.  Dev. Cell. 25:520-533


"The cell biological basis of regulated glucose disposal and the development of insulin-resistance are highly interesting to me and will be important for understanding the development and treatment of Type II Diabetes."