Targeting pathologic G-protein signaling in cardiac and kidney fibrosis

总结：纤维化是多种组织病理性重塑的关键组成部分，没有专门的治疗方法 靶向适应不良性纤维化。心力衰竭（HF）是许多心血管疾病的最终表现， 预后不良的毁灭性疾病，伴随肾功能不全而加重。心肾 综合征（CRS）是心脏和肾脏之间的病理性串扰，包括纤维化增加， 两个器官都失灵d。在CRS 2中，肾功能恶化与HF共存，是 HF患者的死亡率。病理活化的成纤维细胞转变为肌成纤维细胞（MFs）， 组织重塑新型POSTNMerCreMer和Tcf 21 MerCreMer基因敲入小鼠允许靶向的、可诱导的成纤维细胞 体内调制。在HF或肾损伤中，G蛋白偶联受体（GPCRs）的慢性刺激 GPCR激酶2（GRK 2）的病理性上调，GRK 2被募集到膜Gβγ亚单位， 激动剂占据的GPCR。我们的新型小分子Gβγ-GRK 2抑制剂gallein的全身递送， 减弱横向主动脉缩窄（TAC）后的纤维化、HF和GRK 2表达。GRK 2消融， 心肌缺血/再灌注（I/R）损伤后活化的成纤维细胞（GRK 2f 1/f1-POSTNMerCreMer）， 心脏保护，没有由gallein赋予的进一步保护。TAC或I/R损伤导致CRS 2，包括 肾纤维化和功能障碍，以及肾脏特征性GRK 2和内皮素（ET）升高， 功能障碍Gallein减轻TAC或I/R后的肾纤维化、功能障碍、GRK 2表达和ET。 Gβγ-GRK 2抑制还减轻了急性肾I/R损伤后的肾功能障碍和纤维化，提示 阻断Gβγ-GRK 2信号在肾功能不全中的直接保护作用。新型Cre小鼠消融GRK 2 在肾周细胞（FoxD 1Cre）或上皮细胞（Six 2Cre）中，并将用于评价Gβγ- 肾纤维化中的GRK 2信号传导。我们的假设是Gβγ-GRK 2在病理过程中起重要作用， 在HF进展和肾功能不全中的纤维化重构及其抑制 HF、肾损伤和CRS中纤维化重塑的治疗前景2。为了验证我们的假设， 我们提出以下建议：目标1。确定Gβγ-GRK 2的治疗效果和特异性 抑制或消融心脏纤维化和CRS 2。目标二。确定治疗效果， Gβγ-GRK 2抑制或消融在肾纤维化和CRS 2中的特异性。具体目标3：阐明 在心脏和肾脏成纤维细胞中Gβγ-GRK 2抑制的细胞机制，并验证Gβγ-GRK 2作为 小鼠和人类心脏纤维化、肾纤维化和HF的治疗靶点。我们相信这 在各种GRK 2缺失小鼠中验证了Gβγ-GRK 2抑制化合物在心脏和肾脏中的作用。 纤维化，对HF、CRS 2、肾损伤和可能的其他纤维化疾病具有治疗前景。

Summary: Fibrosis is a key component of pathologic remodeling in multiple tissues, no therapies specifically target maladaptive fibrosis. Heart failure (HF), the final manifestation of many cardiovascular pathologies, is a devastating disease with poor prognosis, exacerbated by concomitant kidney dysfunction. Cardiorenal syndrome (CRS) is the pathologic crosstalk between the heart and kidney, including increased fibrosis and failure of both organsd. Worsening renal function co-exists with HF in CRS2 and is a strong predictor of mortality in HF patients. Pathologically activated fibroblasts transition to myofibroblasts (MFs) to exacerbate tissue remodeling. Novel POSTNMerCreMer and Tcf21MerCreMer knock-in mice permit targeted, inducible fibroblast modulation in vivo. In HF or kidney injury, chronic stimulation of G-protein coupled receptors (GPCRs) elicits pathologic upregulation of GPCR kinase 2 (GRK2) that is recruited to membrane Gβγ subunits to modulate agonist-occupied GPCRs. Systemic delivery of our novel small molecule Gβγ-GRK2 inhibitor, gallein, attenuates fibrosis, HF and GRK2 expression following transverse aortic constriction (TAC). GRK2 ablation in activated fibroblasts (GRK2fl/fl-POSTNMerCreMer) after cardiac ischemia/reperfusion (I/R) injury was cardioprotective, with no further protection conferred by gallein. TAC or I/R injury resulted in CRS2, including kidney fibrosis and dysfunction, as well as elevation of GRK2 and endothelin (ET) characteristic of renal dysfunction. Gallein attenuated kidney fibrosis, dysfunction, GRK2 expression and ET following TAC or I/R. Gβγ-GRK2 inhibition also attenuated renal dysfunction and fibrosis following acute renal I/R injury, suggesting a direct protective effect of blocking Gβγ-GRK2 signaling in kidney dysfunction. Novel Cre mice ablate GRK2 in either kidney pericytes (FoxD1Cre) or epithelial cells (Six2Cre) and will be used to evaluate the role of Gβγ- GRK2 signaling in kidney fibrosis. Our hypothesis is that Gβγ-GRK2 plays an important role in pathologic fibrotic remodeling in both HF progression and kidney dysfunction and that its inhibition holds therapeutic promise for fibrotic remodeling in HF, kidney injury and CRS2. To address our hypothesis, we propose the following: Aim 1. Determine the therapeutic efficacy and specificity of Gβγ-GRK2 inhibition or ablation in cardiac fibrosis and CRS2. Aim 2. Determine the therapeutic efficacy and specificity of Gβγ-GRK2 inhibition or ablation in renal fibrosis and CRS2. Specific Aim 3: Elucidate the cellular mechanisms of Gβγ-GRK2 inhibition in cardiac and renal fibroblasts and validate Gβγ-GRK2 as a therapeutic target in mouse and human cardiac fibrosis, kidney fibrosis and HF. We believe this proposal, with Gβγ-GRK2 inhibitory compounds validated in various GRK2 null mice in cardiac and renal fibrosis, holds therapeutic promise for HF, CRS2, kidney injury and possibly other fibrotic diseases.