Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, United States.
Portland State University EXITO Scholars Program, Portland State University, Portland, United States.
Elife. 2022 May 23;11:e78387. doi: 10.7554/eLife.78387.
Sympathetic denervation of the heart following ischemia/reperfusion induced myocardial infarction (MI) is sustained by chondroitin sulfate proteoglycans (CSPGs) in the cardiac scar. Denervation predicts risk of sudden cardiac death in humans. Blocking CSPG signaling restores sympathetic axon outgrowth into the cardiac scar, decreasing arrhythmia susceptibility. Axon growth inhibition by CSPGs can depend on the sulfation status of the glycosaminoglycan (CS-GAG) side chains. Tandem sulfation of CS-GAGs at the 4th (4S) and 6th (6S) positions of n-acetyl-galactosamine inhibits outgrowth in several types of central neurons, but we don't know if sulfation is similarly critical during peripheral nerve regeneration. We asked if CSPG sulfation prevented sympathetic axon outgrowth after MI. Reducing 4S with the 4-sulfatase enzyme Arylsulfatase-B (ARSB) enhanced outgrowth of dissociated rat sympathetic neurons over CSPGs. Likewise, reducing 4S with ARSB restored axon outgrowth from mouse sympathetic ganglia co-cultured with cardiac scar tissue. We quantified enzymes responsible for adding and removing sulfation, and found that CHST15 (4S dependent 6-sulfotransferase) was upregulated, and ARSB was downregulated after MI. This suggests a mechanism for production and maintenance of sulfated CSPGs in the cardiac scar. We decreased 4S,6S CS-GAGs in vivo by transient siRNA knockdown of after MI, and found that reducing 4S,6S restored tyrosine hydroxylase (TH) positive sympathetic nerve fibers in the cardiac scar. Reinnervation reduced isoproterenol induced arrhythmias. Our results suggest that modulating CSPG-sulfation after MI may be a therapeutic target to promote sympathetic nerve regeneration in the cardiac scar and reduce post-MI cardiac arrhythmias.
缺血/再灌注诱导心肌梗死（MI）后心脏的交感神经去神经支配被心脏疤痕中的硫酸软骨素蛋白聚糖（CSPG）持续存在。神经支配预测人类心脏性猝死的风险。阻断 CSPG 信号可恢复交感神经轴突向心脏疤痕的生长，降低心律失常易感性。CSPG 对轴突生长的抑制作用可能取决于糖胺聚糖（CS-GAG）侧链的硫酸化状态。CS-GAG 在 N-乙酰半乳糖胺的第 4 位（4S）和第 6 位（6S）的串联硫酸化可抑制几种类型的中枢神经元的生长，但我们不知道在周围神经再生过程中硫酸化是否同样重要。我们询问 CSPG 硫酸化是否防止了 MI 后交感神经轴突的生长。用 4-硫酸酯酶 Arylsulfatase-B（ARSB）降低 4S 可增强分离的大鼠交感神经元在 CSPG 上的生长。同样，用 ARSB 降低 4S 可恢复与心脏疤痕组织共培养的小鼠交感神经节的轴突生长。我们定量了负责添加和去除硫酸化的酶，发现 CHST15（4S 依赖的 6-硫酸转移酶）在 MI 后上调，ARSB 下调。这表明心脏疤痕中硫酸化 CSPG 产生和维持的一种机制。我们在 MI 后通过短暂的 siRNA 敲低 来降低体内 4S，6S CS-GAGs，发现降低 4S，6S 可恢复心脏疤痕中的酪氨酸羟化酶（TH）阳性交感神经纤维。再神经支配可减少异丙肾上腺素诱导的心律失常。我们的结果表明，调节 MI 后 CSPG 的硫酸化可能是促进心脏疤痕中交感神经再生和减少 MI 后心脏心律失常的治疗靶点。
