Systems Biology and Mathematical Modelling Group, Department of Biochemistry, Microbiology, Cell Biology and Genetics, Biology Section, Science School, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Spain.
Laboratory of Membrane Physiology and Biophysics, Department of Animal Biology, Edaphology and Geology, Biology Section, Science School, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Spain.
Int J Mol Sci. 2021 Nov 10;22(22):12181. doi: 10.3390/ijms222212181.
Alzheimer's disease (AD) is a neurodegenerative disease caused by abnormal functioning of critical physiological processes in nerve cells and aberrant accumulation of protein aggregates in the brain. The initial cause remains elusive-the only unquestionable risk factor for the most frequent variant of the disease is age. Lipid rafts are microdomains present in nerve cell membranes and they are known to play a significant role in the generation of hallmark proteinopathies associated to AD, namely senile plaques, formed by aggregates of amyloid β peptides. Recent studies have demonstrated that human brain cortex lipid rafts are altered during early neuropathological phases of AD as defined by Braak and Braak staging. The lipid composition and physical properties of these domains appear altered even before clinical symptoms are detected. Here, we use a coarse grain molecular dynamics mathematical model to predict the dimensional evolution of these domains using the experimental data reported by our group in human frontal cortex. The model predicts significant size and frequency changes which are detectable at the earliest neuropathological stage (ADI/II) of Alzheimer's disease. Simulations reveal a lower number and a larger size in lipid rafts from ADV/VI, the most advanced stage of AD. Paralleling these changes, the predictions also indicate that non-rafts domains undergo simultaneous alterations in membrane peroxidability, which support a link between oxidative stress and AD progression. These synergistic changes in lipid rafts dimensions and non-rafts peroxidability are likely to become part of a positive feedback loop linked to an irreversible amyloid burden and neuronal death during the evolution of AD neuropathology.
阿尔茨海默病(AD)是一种神经退行性疾病,由神经细胞中关键生理过程的异常功能和大脑中蛋白质聚集物的异常积累引起。其最初的原因仍不清楚——该病最常见变异型的唯一无可争议的危险因素是年龄。脂筏是神经细胞膜中的微区,已知它们在与 AD 相关的标志性蛋白病的产生中发挥重要作用,即由淀粉样β肽聚集形成的老年斑。最近的研究表明,在 Braak 和 Braak 分期定义的 AD 的早期神经病理学阶段,人脑皮质的脂筏发生改变。这些域的脂质组成和物理性质似乎在临床症状出现之前就已经发生了改变。在这里,我们使用粗粒度分子动力学数学模型来预测这些域的尺寸演变,使用我们小组在人额皮质中报告的实验数据。该模型预测了在阿尔茨海默病的最早神经病理学阶段(AD1/II)即可检测到的显著尺寸和频率变化。模拟显示,AD 最先进阶段(ADV/VI)的脂筏数量减少,尺寸增大。与这些变化平行的是,预测还表明非脂筏区域的膜过氧化性同时发生改变,这支持了氧化应激与 AD 进展之间的联系。脂筏尺寸和非脂筏过氧化性的这些协同变化可能成为与 AD 神经病理学演变过程中不可逆的淀粉样蛋白负担和神经元死亡相关的正反馈回路的一部分。