Biasing Myocardial Neuregulin Signaling with Engineered Ligands

描述（由申请人提供）：心肌梗死后心肌细胞损失是慢性心力衰竭（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，参与ErbB受体是一种新兴的、潜在的治疗CHF的策略。我们基于ErbB受体的晶体结构设计了新的二价ErbB配体。二价配体方法使用两个以空间受限方式共价连接的受体结合结构域，这样每个结构域应该能够以二聚体构象结合单独的受体。通过利用受体-配体亲和相互作用，与天然ErbB配体相比，这些二价配体可以偏置ErbB受体信号，优先激活下游途径，从而开启新的治疗机会。正如本提案所示，我们现在已经证明了这种方法的前景，通过在小鼠模型中表明，与天然NRG-1相比，二价NRG-1 （NN）在心脏中诱导更大程度的ErbB4磷酸化，从而在体外和体内产生功能性的心脏保护作用。此外，神经网络在癌细胞中诱导细胞抑制或凋亡表型，其中天然NRG-1具有促肿瘤作用。因此，神经网络可能比天然NRG-1在CHF治疗中带来更大的益处，了解这种方法的机制可能会带来新的CHF治疗方法。我们的具体目的是：目的1：验证心肌细胞NRG-1b信号可以被偏倚以差异激活与CHF相关的细胞内分子通路的假设。目的2：验证ErbB受体配体蛋白工程对心肌细胞ErbB受体信号传导的差异调控。目的3：验证与天然NRG-1b相比，二价NRG-1b （NN）是一种更好的治疗CHF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.