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<h1> JDRF Funded Research</h1>
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 <td>JDRF-Funded Research: Lay Abstract
 
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 PI Name: David Baker 
 Institution Name: University of Washington 
  
 Project duration: 01-December-2018 to 30-November-2020 
 Mechanism: Strategic Research Agreement (SRA) 
 Project grant award: $496,907.91* 
 * Total Grant award amount may vary depending on budget adjustments and it is contingent upon research progress and availability of JDRF research funds. 
 
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 Grant Key: 2-SRA-2018-605-Q-R 
 
 Grant status: Active Grant 
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 Project Title
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 Computational Design of Saccharide Responsive Macrocyclic Peptides
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 <td width="100%" bgcolor = "6699CC" height = "20" align="left"> Objective </td>
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 We propose to develop computationally designed glucose-responsive peptides that can be conjugated to commercial forms of insulin to confer upon them a glucose responsiveness, turning the insulin repeatedly on and off at high and low physiological glucose concentrations. A safe and effective, long-acting glucose-responsive form of insulin would have a tremendous societal impact on the healthcare and suffering of over 387 million diabetic people worldwide (24,25). Objective: To develop computationally designed glucose responsive peptides that can be conjugated to commercial forms of insulin to confer upon them a glucose responsiveness, turning the insulin on and off at high and low physiological glucose concentrations. We propose a 2-year project that will involve three aims: Aim 1 Computational design of saccharide binding macrocycle scaffolds. Hypothesis: We hypothesize it is possible to design synthetic macrocycle peptides with non-natural amino acid side chain substitutions that will support specific binding to disaccharide compounds with cis-diol sub-structures at physiologic pH. Aim 2 Computational design of bicyclic versions of Aim 1 scaffolds with tuned saccharide affinity. Hypothesis: We hypothesize that it will be possible to design bicyclic versions of Aim 1 scaffolds that are capable of sandwiching specific saccharide molecules with well planned hydrogen bond networks, and with tunable affinity at physiological pH. Aim 3 Computational design of bicyclic peptides for tuned glucose responsiveness.   Hypothesis: We hypothesize that the first candidate glucose-responsive peptide macrocycles can be derived through further computational design of Aim 2 bicyclic saccharide binding peptides. By taking this ground up approach, we hope to identify at least two peptide macrocycles that, due to their cooperative folding properties or their finely tuned binding affinities, have the desired biophysical responsiveness to high and low physiological glucose concentration.  For example, the cyclic peptide may adopt one conformation at low glucose concentrations (~4 mM), but adopt an alternative conformation in the presence of high physiological glucose concentrations (~7 mM).
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 <td width="100%" bgcolor = "6699CC" height = "20" align="left"> Background/Rationale </td>
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 The exquisite functions of proteins result from their stable folded 3D structures. Like a string of pearls in necklace, proteins are made of unique sequences of amino acid building blocks, of which there are 20 different chemical types. The ‘stickiness’ of amino acids for each other is what drives proteins to fold into their functional 3D shapes. Insulin is a very special type of protein hormone molecule which is synthesized by cells in the pancreas. Our laboratory has developed pioneering approaches for the computational design of artificial proteins and peptides using the Rosetta software suite. This macromolecular modeling suite can predict 3D protein structures from linear amino acid sequence (6), design artificial proteins with novel topologies (7), and design novel protein-protein interaction interfaces (8,9). Past successes with Rosetta have included the creation of completely new protein fold topologies (7,10), the design of new enzymes (11-13), the production of proteins able of binding therapeutic targets (8,14,15) or small molecule drugs with sub-nanomolar affinities (16,17), and design hyper-stable cyclic mini-proteins with novel topologies representing a new class of drug molecules (19-21). Our Rosetta computational protein design tools have reached a state of technology development which will enable us to generate a new type of glucose-responsive insulin. As the first step in toward this goal, we will use our Rosetta protein design software to design saccharide / glucose responsive peptides that can one day be conjugated to commercial forms of insulin to confer upon them a glucose responsiveness, turning the insulin on and off at high and low physiological glucose concentrations. We believe the glucose-responsive peptide technology can be applied to other proteins where glucose-responsiveness properties are required.
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 <td width="100%" bgcolor = "6699CC" height = "20" align="left"> Description of Project </td>
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 We propose to develop computationally designed glucose-responsive peptides that can be conjugated to commercial forms of insulin to confer upon them a glucose responsiveness, turning the insulin repeatedly on and off at high and low physiological glucose concentrations. A safe and effective, long-acting glucose-responsive form of insulin would have a tremendous societal impact on the healthcare and suffering of over 387 million diabetic people worldwide (24,25). Objective: To develop computationally designed glucose responsive peptides that can be conjugated to commercial forms of insulin to confer upon them a glucose responsiveness, turning the insulin on and off at high and low physiological glucose concentrations.
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 <td width="100%" bgcolor = "6699CC" height = "20" align="left"> Anticipated Outcome </td>
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 Once we have successfully produced functional GRP-modified insulins, we will test a series of the molecules using a mouse model of insulin-deficient diabetes, prepared using streptozotocin (STZ) to induce pancreatic β-cell death (26). Specifically, we will evaluate the function of the modified GRP-insulin derivatives for their ability to normalize blood glucose levels to levels to a normoglycemic state (<200 mg/dL for a mouse) in a glucose tolerance test (IPGTT). Four hours following a single subcutaneous administration of 5 IU/kg insulin or mass equivalent of GRP-insulins, STZ treated mice will be administered an intraparitoneal injection of glucose. Both blood glucose levels and the pharmacokinetic and pharmacodynamic behavior of our GRP-insulins will be monitored. The GRP-insulins that are capable of restoring blood glucose to normogylcemic levels with the same responsiveness as normal control mice will be selected for future pre-clinical studies with the goal of preparing a data package for filing an investigational new drug application with the FDA so that we may begin to study the lead GRP-insulin molecule in safety and efficacy trials in man. A safe and effective, long-acting glucose-responsive form of insulin would have a tremendous societal impact on the healthcare and suffering of over 387 million diabetic people worldwide (24,25).
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 <td width="100%" bgcolor = "6699CC" height = "20" align="left"> Relevance to Type I Diabetes </td>
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 Type 1 diabetes mellitus is a metabolic disease characterized by failure of blood glucose level regulation mechanisms. It is a chronic illness characterized by the body's inability to produce insulin due to the autoimmune destruction of the beta cells in the pancreas which make the protein. Still lacking from the diabetes market is a long acting glucose-responsive form of insulin which can respond to physiological concentrations of blood glucose, turning itself on when serum glucose levels rise above ~6 mM and turning off when glucose falls below ~4 mM (5). We intend to use advanced computational methods to engineer a new type of glucose responsive insulin that has these properties.
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