miR-30调控Calcium/Calcineurin通路在慢性肾脏病心肌保护中的作用

Cardio-renal syndrome (CRS) is a kind of clinical conditions in which cardiac and renal dysfunctions coexist. The morbidity and mortality of CRS is high, however, effective therapies are absent. Elucidation of the molecular pathogenesis is the basis for the development of strategies for CRS prevention and treatment. Here, we will investigate the pathogenesis of myocardial injury induced by chronic kidney diseases (CKD). Our previous studies showed that miR-30, highly expressed in podocytes, downregulated Calcium/Calcineurin signaling to protect podocyte from injury. By MIRZ database and primary experiments, we also found that cardiac myocyte has a high level of miR-30, which could be downregulated by FGF23/AngII, and downregulation of miR-30 activated Calcium/Calcineurin signal pathway leading to cardiomyocyte hypertrophy. Therefore, our hypothesis is follows: increased AngII/FGF23 in circulation of CKD→ cardiomyocyte miR-30s reduction→ Calcium/Calcineurin activation→ cardiac injury. We will conduct the studies including in vitro cardiomyocyte culture, transgenic mice and animal models to validate the hypothesis. The project will explore a novel mechanism of cardiac injury in CKD. The intervention of the signaling, especially inhibiting miR-30s decrease, may be a novel strategy for CRS therapy.

心肾综合征(CRS)的发病率和死亡率高，但目前缺乏有效的治疗措施，阐明CRS的分子病理机制是研发CRS防治措施的基础。本研究将探讨慢性肾脏病起因的心肌细胞损伤的机制。我们已有的研究发现miR-30在足细胞高表达，通过调控Calcium/Calcineurin通路发挥足细胞保护作用。继而我们查询数据库发现心肌细胞同样高表达miR-30；体外细胞实验发现FGF23和AngII能够下调miR-30表达，降低miR-30能够激活Calcium/Calcineurin通路并导致心肌肥大。本研究的假说是：慢性肾脏病(已知循环FGF23/AngII升高)→心肌miR-30s 下调→Calcium/Calcineurin激活→心肌损伤。我们将利用体外细胞培养、转基因动物和疾病模型验证该通路，从而阐明CRS发生的新机制。对慢性肾脏病此通路进行干预，尤其阻止 miR-30s 下调，可能成为CRS治疗的新策略。

心血管并发症现已被认为是影响CKD患者预后的主要因素。而左心室肥厚（LVH）又是最为常见的表型。LVH是CKD的基本心脏改变，可导致更严重的心血管异常，高达65％的透析前患者发生LVH。CKD导致LVH的因素纵多，识别共有机制可增加对CKD诱发LVH的认识，从而为合并心血管并发症的CKD患者提供更可靠的治疗手段。miR-30不仅在心肌组织高表达，也与心脏损伤相关，而且我们之前的研究证明miR-30与Calcineurin通路密切相关，后者在CKD诱导的心肌肥厚中具有重要作用。本研究通过制作5/6肾切除大鼠模型，转基因小鼠模型和体外培养细胞，从三个层面证实CKD通过抑制心肌miRNA-30表达；诱导Calcineurin/NFATc3通路激活，进而导致LVH，补充miRNA-30可以在不改变CKD进展的情况下减轻CKD的LVH、抑制Calcineurin/NFATc3通路激活，从而起到保护心肌细胞的作用。. 研究结果显示：（1）CKD大鼠模型部分：模型大鼠出现CKD表型，并且心肌组织miR-30表达下调，LVH表型明显，Calcineurin/NFATc3通路激活。给予AAV2/9-miR-30-Zsgreen处理，或FGF-23 受体/AngⅡ抑制剂处理后，LVH均得到明显改善。（2）小鼠模型部分：心肌特异性miR-30敲低小鼠出现自发LVH，并且Calcineurin/NFATc3通路激活。FGF-23注射小鼠LVH症状明显，心肌组织miR-30下调，Calcineurin/NFATc3通路激活；给予AAV2/9-miR-30-Zsgreen处理后上述情况得到改善。（3）体外细胞部分： miR-30敲低的H9C2细胞出现肥大，Calcineurin/NFATc3通路激活。原代培养的大鼠心室肌细胞加入促肥大因子FGF-23、Ang II、IS、TGF-β后出现细胞肥大，miR-30表达下调，Calcineurin/NFATc3通路激活。给予miR-30 mimics处理可以明显抑制此效应。. 综上所述，miR-30可以通过抑制CKD心肌组织Calcineurin通路缓解左心室肥厚，从而起到保护心肌的作用。本研究揭示了CKD诱发LVH的新机制，为IV型心肾综合征患者提供了潜在的治疗靶点。