Biasing Myocardial Neuregulin Signaling with Engineered Ligands

描述（由申请人提供）：心肌梗死后的心肌细胞丢失是慢性心力衰竭（CHF）的主要原因，需要保护或再生心肌细胞的治疗来解决这一未满足的临床需求。许多临床前和临床研究已经揭示了ErbB受体介导的信号传导在心脏保护和心脏再生中的重要性。因此，ErbB受体的参与是治疗CHF的新兴和潜在的可转化策略。基于ErbB受体的晶体结构，我们设计了新的二价ErbB配体。二价配体方法使用以空间受限方式共价连接的两个受体结合结构域，使得每个结构域应当能够结合二聚化构象中的单独受体。通过利用受体-配体亲和相互作用，这些二价配体可以使ErbB受体信号传导偏向于与天然ErbB配体相比优先激活下游途径，从而解锁新的治疗机会。如该提案所示，我们现在已经证明了这种方法的前景，表明与天然NRG-1相比，二价NRG-1（NN）在心脏中诱导更大程度的ErbB 4磷酸化，从而在小鼠模型中产生体外和体内功能性心脏保护益处。此外，NN在其中天然NRG-1具有促肿瘤作用的癌细胞中诱导细胞生长抑制或凋亡表型。因此，NN可能比天然NRG-1在CHF治疗中产生更大的益处，并且理解这种方法的机制可能导致CHF治疗的新方法。我们的具体目标是：目标1：验证心肌细胞NRG-1b信号传导可偏向于差异激活CHF相关分子细胞内通路的假设。 目标二：验证蛋白质工程应用于ErbB受体配体可以差异调节心肌细胞ErbB受体信号传导的假设。 目的3：检验与天然NRG-1b相比，二价NRG-1b（NN）是一种上级CHF治疗药物的假设。

DESCRIPTION (provided by applicant): Cardiomyocyte loss following myocardial infarction is a major cause of chronic heart failure (CHF), and therapies that protect or regenerate cardiomyocytes are needed to address this unmet clinical need. Numerous pre-clinical and clinical studies have revealed the importance of ErbB receptor-mediated signaling in both cardioprotection and cardiac regeneration. Thus, engagement of ErbB receptors is an emerging and potentially translatable strategy to treat CHF. We have engineered novel, bivalent ErbB ligands based on the crystal structures of ErbB receptors. The bivalent ligand approach uses two receptor binding domains covalently linked in a spatially constrained manner, such that each domain should be capable of binding separate receptors in a dimerized conformation. By capitalizing on receptor-ligand affinity interactions, these bivalent ligands can bias ErbB recepto signaling to activate downstream pathways preferentially compared to native ErbB ligands, unlocking new therapeutic opportunities. As shown in this proposal, we have now demonstrated the promise of this approach by showing that a bivalent NRG-1 (NN) induces a greater degree of ErbB4 phosphorylation in the heart compared to native NRG-1, resulting in functional cardioprotective benefit in vitro and in vivo in a mouse model. Moreover, NN induces cytostatic or apoptotic phenotypes in cancer cells in which native NRG-1 has pro-neoplastic effects. Thus, NN may lead to greater benefits in CHF treatment than native NRG-1, and understanding the mechanisms of this approach could lead to novel approaches to CHF therapy. Our Specific Aims are: Aim 1: To test the hypothesis that cardiomyocyte NRG-1b signaling can be biased to differentially activate molecular intracellular pathways relevant to CHF. Aim 2: To test the hypothesis that protein engineering applied to ErbB receptor ligands can differentially regulate cardiomyocyte ErbB receptor signaling. Aim 3: To test the hypothesis that bivalent NRG-1b (NN) is a superior CHF therapeutic compared to native NRG-1b.