Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, North Dakota 58202, United States.
ACS Chem Neurosci. 2023 Sep 20;14(18):3431-3443. doi: 10.1021/acschemneuro.3c00319. Epub 2023 Aug 29.
In the central nervous system, serotonergic signaling modulates sleep, mood, and cognitive control. During serotonergic transmission, the synaptic concentration of serotonin is tightly controlled in a spatial and temporal manner by the serotonin transporter (SERT). Dysregulation of this process is implicated in the pathogenesis of major-depressive, obsessive-compulsive, and autism-spectrum disorders, which makes SERT a primary target for prescription therapeutics, most notably selective serotonin reuptake inhibitors (SSRIs). S-Palmitoylation, the reversible addition of a 16-carbon fatty acid to proteins, is an increasingly recognized dynamic post-translational modification responsible for modulating protein kinetics, trafficking, and localization patterns in response to physiologic/cellular stimuli. In this study, we reveal that human SERTs are a target for palmitoylation, and using the irreversible palmitoyl acyltransferase inhibitor 2-bromopalmitate (2BP), we have identified several associated functions. Using a lower dose of 2BP in shorter time frames, inhibition of palmitoylation was associated with reductions in SERT , without changes in or surface expression. With higher doses of 2BP for longer time intervals, inhibition of palmitoylation was consistent with the loss of cell surface and total SERT protein, suggesting palmitoylation is an important mechanism in regulating SERT trafficking and maintenance of SERT protein through biogenic or anti-degradative processes. Additionally, we have identified that treatment with the SSRI escitalopram decreases SERT palmitoylation analogous to 2BP, reducing SERT surface expression and transport capacity. Ultimately, these results reveal that palmitoylation is a major regulatory mechanism for SERT kinetics and trafficking and may be the mechanism responsible for escitalopram-induced internalization and ultimately decreased cellular SERT protein levels.
在中枢神经系统中，5-羟色胺能信号调节睡眠、情绪和认知控制。在 5-羟色胺能传递过程中，5-羟色胺转运体（SERT）以时空方式严格控制突触中 5-羟色胺的浓度。该过程的失调与重度抑郁、强迫症和自闭症谱系障碍的发病机制有关，这使得 SERT 成为处方治疗的主要靶点，尤其是选择性 5-羟色胺再摄取抑制剂（SSRIs）。S-棕榈酰化是一种可逆的将 16 碳脂肪酸添加到蛋白质上的过程，是一种越来越被认可的动态翻译后修饰，负责调节蛋白质动力学、运输和定位模式，以响应生理/细胞刺激。在这项研究中，我们揭示了人类 SERT 是棕榈酰化的靶点，并且使用不可逆的棕榈酰转移酶抑制剂 2-溴棕榈酸（2BP），我们已经确定了几个相关的功能。使用较低剂量的 2BP 并在较短的时间内，棕榈酰化的抑制与 SERT 的减少有关，而 或表面表达没有变化。使用更高剂量的 2BP 并在更长的时间间隔内，棕榈酰化的抑制与细胞膜表面和总 SERT 蛋白的丢失一致，表明棕榈酰化是调节 SERT 运输和通过生物发生或抗降解过程维持 SERT 蛋白的重要机制。此外，我们已经确定，SSRIs 依地普仑的治疗降低了 SERT 的棕榈酰化，类似于 2BP，减少了 SERT 的表面表达和转运能力。最终，这些结果表明，棕榈酰化是 SERT 动力学和运输的主要调节机制，可能是依地普仑诱导内化和最终降低细胞 SERT 蛋白水平的机制。
