An ideal drug candidate is one that inhibits the targeted protein in a way that protein resynthesis is required to overcome the inhibition. The main way of achieving this is by increasing drug residence time. Although not technically increasing residence time, a strategy used to achieve similar results is targeted protein degradation. A few drugs, such as selective estrogen receptor down-regulators (SERDS), have serendipitously achieved this aim. Along with the work of Crews’ laboratory, our laboratory has focused on developing a rational strategy for inducing targeted protein degradation by a small molecule. Our strategy uses boc protected arginine (B3A) as a tag linked to a recognition ligand to induce degradation of its target. Chapter 1 aims to: 1. review the background of residence time and why this is important, 2. highlight inhibitors that lead to our degradation strategy, and 3. review topics relevant to Chapter 3.
In the second chapter of this thesis I will discuss work to elucidate the mechanism of B3A induced degradation. Our hypothesis was that a chaperone recognized the B3A tag and was able to bring the targeted protein to the proteasome. We found ubiquilins, proteins that associate with the proteasome and ubiquitinated proteins, bound to the B3A tag. While developing an assay to verify B3A degradation was mediated by ubiquilins, we surprisingly discovered B3A reduced firefly luciferase.
Further investigation into why the B3A tag alone reduced luciferase, covered in Chapter 3, led to the discovery that Cbz-B3A is a novel mTORC1 signaling inhibitor. The mTORC1 complex has been implicated in many diseases such as cancer and diabetes. Recently, mTORC1 has become a target for prolonging aging. The downstream effects of Cbz-B3A inhibition of mTORC1 signaling are unique and appear to be modulated by ubiquilins.
|Commitee:||Griffith, Leslie, Marr, Michael, Punzo, Claudio|
|Department:||Molecular and Cell Biology|
|School Location:||United States -- Massachusetts|
|Source:||DAI-B 77/02(E), Dissertation Abstracts International|
|Subjects:||Molecular biology, Cellular biology, Biochemistry|
|Keywords:||Drug candidates, Luciferase, Protein degradation, Ubiquitin, mTOR|
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