Department of Environmental Medicine Toxicology Training Program, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America.
Department of Pulmonary and Critical Care Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America.
PLoS One. 2022 Jul 28;17(7):e0271608. doi: 10.1371/journal.pone.0271608. eCollection 2022.
Transforming growth factor beta (TGF-β) induced myofibroblast differentiation is central to the pathological scarring observed in Idiopathic Pulmonary Fibrosis (IPF) and other fibrotic diseases. Our lab has recently identified expression of GPR68 (Ovarian Cancer Gene Receptor 1, OGR1), a pH sensing G-protein coupled receptor, as a negative regulator of TGF-β induced profibrotic effects in primary human lung fibroblasts (PHLFs). We therefore hypothesized that small molecule activators of GPR68 would inhibit myofibroblast differentiation. Ogerin is a positive allosteric modulator (PAM) of GPR68, inducing a leftward shift of the dose response curve to proton induced signaling. Using PHLFs derived from patients with both non-fibrotic and IPF diagnoses, we show that Ogerin inhibits, and partially reverses TGF-β induced myofibroblast differentiation in a dose dependent manner. This occurs at the transcriptional level without inhibition of canonical TGF-β induced SMAD signaling. Ogerin induces PKA dependent CREB phosphorylation, a marker of Gαs pathway activation. The ability of Ogerin to inhibit both basal and TGF-β induced collagen gene transcription, and induction of Gαs signaling is enhanced at an acidic pH (pH 6.8). Similar findings were also found using fibroblasts derived from dermal, intestinal, and orbital tissue. The biological role of GPR68 in different tissues, cell types, and disease states is an evolving and emerging field. This work adds to the understanding of Gαs coupled GPCRs in fibrotic lung disease, the ability to harness the pH sensing properties of GPR68, and conserved mechanisms of fibrosis across different organ systems.
转化生长因子-β（TGF-β）诱导的肌成纤维细胞分化是特发性肺纤维化（IPF）和其他纤维化疾病中观察到的病理性瘢痕形成的核心。我们的实验室最近发现，G 蛋白偶联受体 68（卵巢癌基因受体 1，OGR1）的表达，一种 pH 感应 G 蛋白偶联受体，作为原代人肺成纤维细胞（PHLF）中 TGF-β诱导的促纤维化作用的负调节剂。因此，我们假设 GPR68 的小分子激活剂将抑制肌成纤维细胞分化。Ogerin 是 GPR68 的正变构调节剂（PAM），诱导质子诱导信号的剂量反应曲线向左移位。使用源自非纤维化和 IPF 诊断患者的 PHLF，我们表明 Ogerin 以剂量依赖性方式抑制并部分逆转 TGF-β诱导的肌成纤维细胞分化。这发生在转录水平上，而不抑制经典的 TGF-β诱导的 SMAD 信号。Ogerin 诱导 PKA 依赖性 CREB 磷酸化，这是 Gαs 途径激活的标志物。Ogerin 抑制基础和 TGF-β诱导的胶原基因转录的能力，以及 Gαs 信号的诱导，在酸性 pH（pH 6.8）下增强。在源自皮肤、肠道和眼眶组织的成纤维细胞中也发现了类似的发现。GPR68 在不同组织、细胞类型和疾病状态中的生物学作用是一个不断发展和新兴的领域。这项工作增加了对纤维化肺疾病中 Gαs 偶联 GPCR 的理解，利用 GPR68 的 pH 感应特性，以及不同器官系统中纤维化的保守机制。
