Department of Cardiology, The First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
Department of Pharmacy, The Second Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
Mol Med Rep. 2017 Dec;16(6):8953-8963. doi: 10.3892/mmr.2017.7714. Epub 2017 Oct 4.
Recent studies have indicated the existence of an endogenous sulfur dioxide (SO2)‑generating system in the cardiovascular system. The present study aimed to discuss the function and regulatory mechanism of gaseous signal molecule SO2 in inhibiting apoptosis and endoplasmic reticulum stress (ERS) via the Hippo‑MST signaling pathway to improve myocardial fibrosis of diabetic rats. A total of 40 male Sprague‑Dawley rats were randomly divided into four groups (10 rats per group): Normal control group (control group), diabetic rats group [streptozotocin (STZ) group], SO2 intervention group (STZ+SO2 group) and diabetes mellitus rats treated with L‑Aspartic acid β‑hydroxamate (HDX) group (HDX group). Diabetic rats models were established by intra‑peritoneal injection of STZ (40 mg/kg) Following model establishment, intra‑peritoneal injection of Na2SO3/NaHSO3 solution (0.54 mmol/kg) was administered in the STZ+SO2 group, and HDX solution (25 mg/kg/week) was administered in the HDX group. A total of 4 weeks later, echocardiography was performed to evaluate rats' cardiac function; Masson staining, terminal deoxynucleotidyl transferase dUTP nick end labeling staining and transmission electron microscopy examinations were performed to observe myocardial morphological changes. ELISA was employed to determine the SO2 content. Western blot analysis was performed to detect the expression of proteins associated with apoptosis, ERS and the Hippo‑MST signalling pathway. Compared with the control group, the STZ group and HDX group had a disordered arrangement of myocardial cells with apparent myocardial fibrosis, and echocardiography indicated that the cardiac function was lowered, there was an obvious increase of apoptosis in myocardial tissue, the expression levels of apoptosis‑associated protein B‑cell lymphoma associated protein X, caspase‑3 and caspase‑9 were upregulated, and Bcl‑2 expression was downregulated. The expression of ERS and Hippo‑MST pathway‑associated proteins, including CHOP, GRP94, MST1 and MST2, were significantly upregulated. By contrast, these above‑mentioned changes were reversed by SO2 treatment. Compared with STZ group, the HDX group had a further increase of myocardial fibrosis and apoptosis, while there were no statistically significant differences in the expression of Bax/Bcl‑2, caspase‑3, caspase‑9 and ERS and Hippo‑MST pathway‑associated proteins. The results of the present study demonstrated that the gaseous signal molecule SO2 can effectively improve the myocardial fibrosis of diabetic rats, and its mechanism may be associated with reduced apoptosis and ERS by downregulated Hippo‑MST pathway.
最近的研究表明，心血管系统中存在内源性二氧化硫（SO2）生成系统。本研究旨在探讨气态信号分子 SO2 通过 Hippo-MST 信号通路抑制细胞凋亡和内质网应激（ERS）从而改善糖尿病大鼠心肌纤维化的功能和调节机制。
将 40 只雄性 Sprague-Dawley 大鼠随机分为四组（每组 10 只）：正常对照组（对照组）、糖尿病大鼠组[链脲佐菌素（STZ）组]、SO2 干预组（STZ+SO2 组）和糖尿病大鼠用 L-天冬氨酸 β-羟肟酸（HDX）治疗组（HDX 组）。通过腹腔注射 STZ（40mg/kg）建立糖尿病大鼠模型。模型建立后，STZ+SO2 组给予亚硫酸钠/亚硫酸氢钠溶液（0.54mmol/kg）腹腔注射，HDX 组给予 HDX 溶液（25mg/kg/周）腹腔注射。4 周后，行超声心动图评估大鼠心功能；行 Masson 染色、末端脱氧核苷酸转移酶 dUTP 缺口末端标记染色和透射电镜检查观察心肌形态变化。采用 ELISA 法测定 SO2 含量。采用 Western blot 法检测与细胞凋亡、ERS 和 Hippo-MST 信号通路相关的蛋白表达。
与对照组相比，STZ 组和 HDX 组心肌细胞排列紊乱，心肌纤维化明显，超声心动图提示心功能降低，心肌组织细胞凋亡明显增加，凋亡相关蛋白 B 细胞淋巴瘤相关蛋白 X、半胱氨酸天冬氨酸蛋白酶-3 和半胱氨酸天冬氨酸蛋白酶-9 的表达上调，Bcl-2 表达下调。ERS 和 Hippo-MST 通路相关蛋白 CHOP、GRP94、MST1 和 MST2 的表达明显上调。而 SO2 处理可逆转上述变化。与 STZ 组相比，HDX 组心肌纤维化和细胞凋亡进一步增加，而 Bax/Bcl-2、caspase-3、caspase-9 和 ERS 及 Hippo-MST 通路相关蛋白的表达无统计学差异。
本研究结果表明，气态信号分子 SO2 可有效改善糖尿病大鼠心肌纤维化，其机制可能与下调 Hippo-MST 通路减少细胞凋亡和 ERS 有关。
