中国神经再生研究(英文版) ›› 2022, Vol. 17 ›› Issue (3): 488-496.doi: 10.4103/1673-5374.320967

• 综述:脑损伤修复保护与再生 • 上一篇    下一篇

磺酰脲受体1(SUR1)的短形式及其对受损大脑中的功能

  

  • 出版日期:2022-03-15 发布日期:2021-10-14

The short form of the SUR1 and its functional implications in the damaged brain

Iván Alquisiras-Burgos1, Javier Franco-Pérez2, Moisés Rubio-Osornio3, Penélope Aguilera1, *   

  1. 1Laboratorio de Patología Vascular Cerebral, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, CDMX, Mexico; 2Laboratorio de Formación Reticular, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, CDMX, Mexico; 3Laboratorio Experimental de Enfermedades Neurodegenerativas, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, CDMX, Mexico.
  • Online:2022-03-15 Published:2021-10-14
  • Contact: Penélope Aguilera, PhD, penelope.aguilera@innn.edu.mx.
  • Supported by:
    This work was supported by the CONACYT (FORDECYT-PRONACES/170733/2020 to PA and CB-2016-287959 to MRO). IAB is a doctoral student from Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México (UNAM) and beneficiary of scholarship No. 275610 from CONACYT. 

摘要: Neural Regen Res:磺酰脲受体短形式存在及其对脑功能的意义
    磺酰脲受体(SUR)属于三磷酸腺苷(ATP)结合盒转运体家族;SUR与离子通道相关,并且作为孔的打开或关闭的调节亚单位。Abcc8和Abcc9基因分别编码SUR1和SUR2蛋白。SUR1转录编码一种由1582个氨基酸组成的蛋白质,在胰腺、大脑、心脏和其他组织中表达,其质量约为140-177 kDa。SUR1分别与Kir6.2和TRPM4结合形成KATP通道和非选择性阳离子通道。Abbc8和9是交替剪接的,产生的转录物编码SUR1和SUR2的不同亚型,这两种亚型已被不同的实验检测到。有趣的是,对磺酰脲类药物的结合分析和Western印迹法的使用,使得SUR短形式(~65kda)的检测成为可能。SUR1变异体的身份尚未阐明,一些研究者认为较短的形式是不特定的。然而,免疫沉淀分析表明,SUR2短形式是功能通道的一部分,甚至与心脏受体的典型形式共存。这一证据证实了SURs短形式的结构是完全功能性的,并且不丧失与通道相互作用的能力。由于SUR短形式的结构改变改变了其与三磷酸腺苷的亲和力,因此对其表达的调控可能在三磷酸腺苷浓度降低的病理学中具有优势,并成为诱导神经保护的治疗靶点。值得注意的是,SUR1变体表达可能是由与大脑能量底物减少相关的条件(例如在脑卒中和癫痫期间)诱导的。
    来自墨西哥国立神经病学和神经科学研究所的Penélope Aguilera团队认为在三磷酸腺苷降低的脑病理中观察到65 kDa SUR1蛋白,即可在代谢应激条件下以降低三磷酸腺苷浓度来调节离子通道的活性。该证据与在细胞培养中进行的研究相吻合,其中对磺酰脲具有高(140 kDa)或低亲和力(65 kDa)的SUR1变体的表达在很大程度上取决于培养条件。在高葡萄糖(25 mM)下,细胞同时表达两种磺酰脲受体,与格列本脲的亲和力高(Kd = 1 nM)和亲和力低(Kd = 100 nM–1μM)。在低葡萄糖培养基(11 mM)中培养的细胞表达低亲和力受体,并失去高亲和力磺酰脲结合位点。因此,SUR1的短形式变体可能来自替代剪接,并且可能取决于外源性刺激。另一方面,免疫沉淀分析表明,SUR2短形式(65和28 kDa)是功能通道的一部分,甚至与140 kDa受体的典型形式共存。不同的SUR形式可以共同组装成KATP通道,并产生不同的代谢敏感性和药理学特征。短形式SUR1的共组装可能会产生一个对三磷酸腺苷敏感性更高的通道,但也会产生一个具有更大电流容量的通道。这种情况在病理形式中具有重要意义,在这种病理形式中,短形式的SUR可能参与受损伤的大脑中发生的离子失衡。SUR1在中枢神经系统中的功能尚未被详细描述。尽管有证据表明短形式SUR整合了功能性通道,但没有证据表明短形式SUR1蛋白功能存在。已经进行了多次尝试来证明65kDa蛋白质的特性,但是需要进一步的实验来阐明SUR1亚型在大脑中的参与。基于短形式SUR2的行为和SUR1在脑卒中中过度表达的检测,提出SUR1的短型变体在疾病发展过程中对大脑有功能影响。 
文章在《中国神经再生研究(英文版)》杂志2022年 3月3  期发表。

https://orcid.org/0000-0003-2288-1251 (Penélope Aguilera)

Abstract: Sulfonylurea receptor (SUR) belongs to the adenosine 5′-triphosphate (ATP)-binding cassette (ABC) transporter family; however, SUR is associated with ion channels and acts as a regulatory subunit determining the opening or closing of the pore. Abcc8 and Abcc9 genes code for the proteins SUR1 and SUR2, respectively. The SUR1 transcript encodes a protein of 1582 amino acids with a mass around 140–177 kDa expressed in the pancreas, brain, heart, and other tissues. It is well known that SUR1 assembles with Kir6.2 and TRPM4 to establish KATP channels and non-selective cation channels, respectively. Abbc8 and 9 are alternatively spliced, and the resulting transcripts encode different isoforms of SUR1 and SUR2, which have been detected by different experimental strategies. Interestingly, the use of binding assays to sulfonylureas and Western blotting has allowed the detection of shorter forms of SUR (~65 kDa). Identity of the SUR1 variants has not been clarified, and some authors have suggested that the shorter forms are unspecific. However, immunoprecipitation assays have shown that SUR2 short forms are part of a functional channel even coexisting with the typical forms of the receptor in the heart. This evidence confirms that the structure of the short forms of the SURs is fully functional and does not lose the ability to interact with the channels. Since structural changes in short forms of SUR modify its affinity to ATP, regulation of its expression might represent an advantage in pathologies where ATP concentrations decrease and a therapeutic target to induce neuroprotection. Remarkably, the expression of SUR1 variants might be induced by conditions associated to the decrease of energetic substrates in the brain (e.g. during stroke and epilepsy). In this review, we want to contribute to the knowledge of SUR1 complexity by analyzing evidence that shows the existence of short SUR1 variants and its possible implications in brain function.

Key words: brain edema, epilepsy, Parkinson’s disease, stroke, sulfonylurea receptor 1, SUR1, traumatic brain injury, TRPM4