In the activation of transcription the GACKIX motif, a small conserved domain plays an important role with two potential docking sites for activators and has been found in CBP and its homolog p300 as well as the unrelated coactivator ARC105. The functions of activator*GACKIX domain complexes are diverse and include cellular growth, hematopoiesis, synaptic plasticity, and lipid homeostasis; thus, dysregulation of these complexes are also linked to many diseases from leukemia to Alzheimer's and Huntington's disease. Chemical tools are sought to dissect the individual functions of activator*GACKIX domain complexes and to provide a potential therapeutic model. However small molecules have yet to be designed that can distinguish between the GACKIX domain of a particular coativator such as p300 versus CBP. In this research plan the site-directed strategy known as Tethering is applied to match orthogonal disulfide-containing fragments with cysteine-modified GACKIX (cysGACKIX) domain. First a liquid chromatography-mass spectrometry Tethering screen was used to identify disulfide fragments that target the MLL-binding site of the cysGACKIX domain. A novel fluorescence polarization Tethering screen streamlined the identification of small molecules inhibitors directed at the c-Myb and CREB- binding site of the cysGACKIX domain. The disulfide fragments will be converted into covalent irreversible probes. Tethering will be extended using the most selective and potent small molecules inhibitors to assess the function of activators such as CREB, and MLL interactions with GACKIX domain of CBP, p300, and ARC105 in cells.

Public Health Relevance

The GACKIX motif is conserved domain within coactivator proteins that forms transient complexes with activators to express specific genes. The role of GACKIX in these proteins is difficult to distinguish due to their homology and partial functional redundancy. With the site- directed strategy of Tethering highly specific molecule*GACKIX protein pairs will be developed and these probes will be used to dissect the role of individual activator*GACKIX domains of CBP, p300 and ARC105 in gene expression.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31GM113561-03
Application #
9304262
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Brown, Patrick
Project Start
2015-07-01
Project End
2017-10-31
Budget Start
2017-07-01
Budget End
2017-10-31
Support Year
3
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109