Tang Gang, Shen Yi, Gao Pan, Song Shuang-Shuang, Si Liang-Yi
Department of Geriatrics, Southwest Hospital, Third Military Medical University, Chongqing, China.
In Vitro Cell Dev Biol Anim. 2018 Mar;54(3):250-256. doi: 10.1007/s11626-017-0215-5. Epub 2018 Jan 17.
Cardiac hypertrophy plays a major role in heart failure and is related to patient morbidity and mortality. Calcium overloading is a main risk for cardiac hypertrophy, and Na/K-ATPase (NKA) has been found that it could not only regulate intracellular Na levels but also control the intracellular Ca ([Ca]) level through Na/Ca-exchanger (NCX). Recent studies have reported that klotho could affect [Ca] level. In this study, we aimed at exploring the role of klotho in improving isoproterenol-induced hypertrophic response of H9C2 cells. The H9C2 cells were randomly divided into control and isoproterenol (ISO) (10 μM) groups. Klotho protein (10 μg/ml) or NKAα2 siRNA was used to determine the changes in isoproterenol-induced hypertrophic response. The alterations of [Ca] level were measured by spectrofluorometry. Our results showed that H9C2 cells which were treated with isoproterenol presented a higher level of [Ca] and hypertrophic gene expression at 24 and 48 h compared with the control group. Moreover, the expressions of NKAα1 and NKAα2 were both increased in control and ISO groups after treating with klotho protein; meanwhile, the NKA activity was increased and NCX activity was decreased after treatment. Consistently, the [Ca] level and hypertrophic gene expression were decreased in ISO group after klotho protein treatment. However, these effects were both prevented by transfecting with NKAα2 siRNA. In conclusion, these findings demonstrated that klotho inhibits isoproterenol-induced hypertrophic response in H9C2 cells by activating NKA and inhibiting the reverse mode of NCX and this effect may be associated with the upregulation of NKAα2 expression.
心肌肥厚在心力衰竭中起主要作用，且与患者的发病率和死亡率相关。钙超载是心肌肥厚的主要风险因素，研究发现钠钾ATP酶（NKA）不仅可以调节细胞内钠离子水平，还能通过钠钙交换体（NCX）控制细胞内钙离子（[Ca]）水平。最近的研究报道，klotho蛋白可以影响[Ca]水平。在本研究中，我们旨在探讨klotho蛋白在改善异丙肾上腺素诱导的H9C2细胞肥大反应中的作用。将H9C2细胞随机分为对照组和异丙肾上腺素（ISO，10 μM）组。使用klotho蛋白（10 μg/ml）或NKAα2小干扰RNA（siRNA）来测定异丙肾上腺素诱导的肥大反应的变化。通过荧光分光光度法测量[Ca]水平的变化。我们的结果显示，与对照组相比，用异丙肾上腺素处理的H9C2细胞在24小时和48小时时呈现出更高水平的[Ca]和肥大基因表达。此外，在用klotho蛋白处理后，对照组和ISO组中NKAα1和NKAα2的表达均增加；同时，处理后NKA活性增加而NCX活性降低。一致的是，klotho蛋白处理后ISO组中的[Ca]水平和肥大基因表达降低。然而，这些作用均通过转染NKAα2 siRNA而被阻断。总之，这些发现表明，klotho蛋白通过激活NKA并抑制NCX的反向模式来抑制异丙肾上腺素诱导的H9C2细胞肥大反应，且这种作用可能与NKAα2表达上调有关。
