Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA.
Int J Mol Sci. 2023 Jul 24;24(14):11868. doi: 10.3390/ijms241411868.
The protein sarcospan (SSPN) is an integral member of the dystrophin-glycoprotein complex (DGC) and has been shown to be important in the heart during the development and the response to acute stress. In this study, we investigated the role of SSPN in the cardiac response to acute ischemia-reperfusion (IR) injury in SSPN-deficient (SSPN) mice. First, the hemodynamic response of SSPN mice was tested and was similar to SSPN (wild-type) mice after isoproterenol injection. Using the in situ Langendorff perfusion method, SSPN hearts were subjected to IR injury and found to have increased infarct size and arrhythmia susceptibility compared to SSPN. Ca handling was assessed in single cardiomyocytes and diastolic Ca levels were increased after acute β-AR stimulation in SSPN but not SSPN. It was also found that SSPN cardiomyocytes had reduced Ca SR content compared to SSPN but similar SR Ca release. Next, we used qRT-PCR to examine gene expression of Ca handling proteins after acute IR injury. SSPN hearts showed a significant decrease in L-type Ca channels and a significant increase in Ca release channel (RyR2) expression. Interestingly, under oxidizing conditions reminiscent of IR, SSPN cardiomyocytes, had increased HO-induced reactive oxygen species production compared to SSPN. Examination of oxidative stress proteins indicated that NADPH oxidase 4 and oxidized CAMKII were increased in SSPN hearts after acute IR injury. These results suggest that increased arrhythmia susceptibility in SSPN hearts post-IR injury may arise from alterations in Ca handling and a reduced capacity to regulate oxidative stress pathways.
肌萎缩蛋白聚糖（SSPN）是营养不良蛋白聚糖复合物（DGC）的固有成员，已被证明在心脏发育和对急性应激的反应中具有重要作用。在这项研究中，我们研究了 SSPN 在 SSPN 缺陷（SSPN）小鼠心脏对急性缺血再灌注（IR）损伤的反应中的作用。首先，测试了 SSPN 小鼠的血液动力学反应，发现其对异丙肾上腺素的注射反应与 SSPN（野生型）相似。使用原位 Langendorff 灌流方法，发现 SSPN 心脏的 IR 损伤导致梗塞面积增加和心律失常易感性增加，与 SSPN 相比。在急性β-AR 刺激后，评估了单个心肌细胞中的 Ca 处理，发现 SSPN 的舒张期 Ca 水平增加，但 SSPN 没有增加。还发现，与 SSPN 相比，SSPN 心肌细胞的 CaSR 含量减少，但 SR Ca 释放相似。接下来，我们使用 qRT-PCR 检查急性 IR 损伤后 Ca 处理蛋白的基因表达。SSPN 心脏显示 L 型 Ca 通道表达显著减少，Ca 释放通道（RyR2）表达显著增加。有趣的是，在类似于 IR 的氧化条件下，SSPN 心肌细胞在 HO 诱导的活性氧产生方面的活性氧产生高于 SSPN。氧化应激蛋白的检测表明，急性 IR 损伤后 SSPN 心脏中的 NADPH 氧化酶 4 和氧化的钙调蛋白依赖性蛋白激酶 II（CAMKII）增加。这些结果表明，SSPN 心脏在 IR 后心律失常易感性增加可能源于 Ca 处理的改变和调节氧化应激途径的能力降低。
