中国神经再生研究(英文版) ›› 2022, Vol. 17 ›› Issue (2): 271-276.doi: 10.4103/1673-5374.317956

• 综述:神经损伤修复保护与再生 • 上一篇    下一篇

轴突再生中胆固醇合成的抑制或耗竭

  

  • 出版日期:2022-02-15 发布日期:2021-10-08

Cholesterol synthesis inhibition or depletion in axon regeneration

Bor Luen Tang*   

  1. Department of Biochemistry, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
  • Online:2022-02-15 Published:2021-10-08
  • Contact: Bor Luen Tang, PhD, bchtbl@nus.edu.sg.

摘要: Neural Regen Res: 轴突再生与胆固醇水平的关系
     研究显示降低胆固醇可促进轴突在再生过程中的生长,但是胆固醇的降低是如何产生这种效果的?他汀类药物可能的作用模式是由于对所有基于甲戊酸的异戊烯酮合成的全面抑制和蛋白质预酸化的相应衰减。已知的小GTPase RhoA及其效应器Rho相关连续激酶的轴突生长抑制作用,它是许多髓鞘相关抑制剂轴突生长锥生长抑制或塌陷活性的中心,取决于适当的C端预酸化Rho。因此,通过减少预酸化降低RhoA介导的生长锥生长抑制活性,似乎与降低胆固醇增强的中枢神经系统轴突再生有关。所有需要预酸化的小GTPass和其他分子将受到影响,包括Rac1和Rab家族成员。前期研究表明洛伐他汀的内酯前体可能具有轴突生长促进活性,超出HMG-CoA还原酶抑制,同样也有他汀类化合物及其衍生物。最新研究结果表明,通过药理学或遗传学干预,胆固醇消耗或合成抑制可用于增强损伤后轴突(尤其是中枢神经系统神经元)再生。可想而知,全身或局部载体靶向递送胆固醇消耗化合物或其组合可能有益于外周或中枢神经损伤中的轴突再生。这也在一定程度上符合胆固醇稳态失调导致多种神经退行性疾病的观点,如阿尔茨海默病、帕金森病和亨廷顿病。他汀类药物等降胆固醇药物在一些神经退行性疾病动物模型中确实显示出益处。
     来自新加坡国立大学杨璐龄医学院的Bor Luen Tang认为虽然轴突生长锥细胞的特异性胆固醇耗竭可能促进轴突的生长,但少突胶质细胞的耗竭可能损害髓鞘形成。可以想象,大幅度降低胆固醇会对系统性或神经元特异性产生有害影响。胆固醇的临界量可能对调节神经元功能和存活的关键信号分子的正常功能很重要。除了明显需要足够的胆固醇来避免低髓鞘化外,需要已知胆固醇调节突触传递,胆固醇水平的变化可能因此影响突触强度和可塑性。Sonic hedgehog的活性和信号传导对神经元存活、神经发生和神经再生非常重要,严重依赖于胆固醇的共价修饰。为了促进轴突再生而对胆固醇水平进行的任何治疗性操作都需要仔细权衡和精确执行。因此,在这种方法成为临床可转化的方法之前,还有很多需要商榷之处。
文章在《中国神经再生研究(英文版)》杂志2022年 2 月 2 期发表。

https://orcid.org/0000-0002-1925-636X (Bor Luen Tang)

Abstract: Cholesterol is biosynthesized by all animal cells. Beyond its metabolic role in steroidogenesis, it is enriched in the plasma membrane where it has key structural and regulatory functions. Cholesterol is thus presumably important for post-injury axon regrowth, and this notion is supported by studies showing that impairment of local cholesterol reutilization impeded regeneration. However, several studies have also shown that statins, inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, are enhancers of axon regeneration, presumably acting through an attenuation of the mevalonate isoprenoid pathway and consequent reduction in protein prenylation. Several recent reports have now shown that cholesterol depletion, as well as inhibition of cholesterol synthesis per se, enhances axon regeneration. Here, I discussed these findings and propose some possible underlying mechanisms. The latter would include possible disruptions to axon growth inhibitor signaling by lipid raft-localized receptors, as well as other yet unclear neuronal survival signaling process enhanced by cholesterol lowering or depletion.

Key words: axon regeneration, cholesterol, 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), lipid raft, methyl-β-cyclodextrin, Nogo receptor, prominin-1, RhoA, statins