Abstract：
Cardiac arrhythmia treatment is a clinical challenge necessitating safer and more effective therapies. Recent studies have highlighted the role of the perinexus, an intercalated disc nanodomain enriched in voltage-gated sodium channels including both Nav1.5 and β1 subunits, adjacent to gap junctions. These findings offer insights into action potential conduction in the heart. A 19-amino acid SCN1B (β1/β1B) mimetic peptide, βadp1, disrupts VGSC beta subunit-mediated adhesion in cardiac perinexii, inducing arrhythmogenic changes. We aimed to explore βadp1\'s mechanism and develop novel SCN1B mimetic peptides affecting β1-mediated adhesion. Using patch clamp assays in neonatal rat cardiomyocytes and electric cell substrate impedance sensing (ECIS) in β1-expressing cells, we observed βadp1 maintained inhibitory effects for up to 5 h. A shorter peptide (LQLEED) based on the carboxyl-terminus of βadp1 mimicked this inhibitory effect, while dimeric peptides containing repeated LQLEED sequences paradoxically promoted intercellular adhesion over longer time courses. Moreover, we found a link between these peptides and β1-regulated intramembrane proteolysis (RIP) - a signaling pathway effecting gene transcription including that of VGSC subunits. βadp1 increased RIP continuously over 48 h, while dimeric agonists acutely boosted RIP for up to 6 h. In the presence of DAPT, an RIP inhibitor, βadp1\'s effects on ECIS-measured intercellular adhesion was reduced, suggesting a relationship between RIP and the peptide\'s inhibitory action. In conclusion, novel SCN1B (β1/β1B) mimetic peptides are reported with the potential to modulate intercellular VGSC β1-mediated adhesion, potentially through β1 RIP. These findings suggest a path towards the development of anti-arrhythmic drugs targeting the perinexus.
摘要：
心律失常治疗是一项临床挑战，需要更安全和更有效的治疗方法。最近的研究强调了围联的作用，富含电压门控钠通道的插层圆盘纳米结构域，包括Nav1.5和β1亚基，毗邻间隙连接。这些发现提供了对心脏动作电位传导的见解。一种19个氨基酸的SCN1B（β1/β1B）模拟肽，βadp1，破坏VGSCβ亚基介导的心脏附着性，诱导心律失常性变化。我们旨在探索βadp1的机制，并开发影响β1介导的粘附的新型SCN1B模拟肽。在新生大鼠心肌细胞中使用膜片钳测定法和β1表达细胞中的电细胞底物阻抗传感（ECIS），我们观察到βadp1维持抑制作用长达5小时。基于βadp1羧基末端的较短肽（LQLEED）模拟了这种抑制作用，而含有重复LQLEED序列的二聚体肽在较长时间的过程中矛盾地促进细胞间粘附。此外，我们发现这些肽与β1调节的膜内蛋白水解（RIP）之间存在联系，RIP是影响基因转录的信号通路，包括VGSC亚基。βadp1在48h内连续增加RIP，而二聚体激动剂急剧增强RIP长达6小时。在DAPT的存在下，一种RIP抑制剂,βadp1对ECIS测量的细胞间粘附的影响降低，提示RIP与肽的抑制作用之间的关系。总之,据报道，新型SCN1B（β1/β1B）模拟肽具有调节细胞间VGSCβ1介导的粘附的潜力，可能通过β1RIP。这些发现为开发针对外周的抗心律失常药物提供了途径。
