Molecular and Cellular Neuroscience Division, National Brain Research Centre, Manesar, Gurgaon, Haryana, 122052, India.
J Transl Med. 2024 May 27;22(1):503. doi: 10.1186/s12967-024-05121-x.
Prion diseases are transmissible and fatal neurodegenerative diseases characterized by accumulation of misfolded prion protein isoform (PrP), astrocytosis, microgliosis, spongiosis, and neurodegeneration. Elevated levels of cell membrane associated PrP protein and inflammatory cytokines hint towards the activation of death receptor (DR) pathway/s in prion diseases. Activation of DRs regulate, either cell survival or apoptosis, autophagy and necroptosis based on the adaptors they interact. Very little is known about the DR pathways activation in prion disease. DR3 and DR5 that are expressed in normal mouse brain were never studied in prion disease, so also their ligands and any DR adaptors. This research gap is notable and investigated in the present study.
C57BL/6J mice were infected with Rocky Mountain Laboratory scrapie mouse prion strain. The progression of prion disease was examined by observing morphological and behavioural abnormalities. The levels of PrP isoforms and GFAP were measured as the marker of PrP accumulation and astrocytosis respectively using antibody-based techniques that detect proteins on blot and brain section. The levels of DRs, their glycosylation and ectodomain shedding, and associated factors warrant their examination at protein level, hence western blot analysis was employed in this study.
Prion-infected mice developed motor deficits and neuropathology like PrP accumulation and astrocytosis similar to other prion diseases. Results from this research show higher expression of all DR ligands, TNFR1, Fas and p75NTR but decreased levels DR3 and DR5. The levels of DR adaptor proteins like TRADD and TRAF2 (primarily regulate pro-survival pathways) are reduced. FADD, which primarily regulate cell death, its level remains unchanged. RIPK1, which regulate pro-survival, apoptosis and necroptosis, its expression and proteolysis (inhibits necroptosis but activates apoptosis) are increased.
The findings from the present study provide evidence towards the involvement of DR3, DR5, DR6, TL1A, TRAIL, TRADD, TRAF2, FADD and RIPK1 for the first time in prion diseases. The knowledge obtained from this research discuss the possible impacts of these 16 differentially expressed DR factors on our understanding towards the multifaceted neuropathology of prion diseases and towards future explorations into potential targeted therapeutic interventions for prion disease specific neuropathology.
朊病毒病是一种可传播且致命的神经退行性疾病，其特征是错误折叠的朊病毒蛋白异构体（PrP）的积累、星形胶质细胞增生、小胶质细胞增生、海绵状变性和神经退行性变。细胞膜相关 PrP 蛋白和炎性细胞因子水平升高表明朊病毒病中存在死亡受体（DR）途径的激活。DR 的激活根据其相互作用的衔接蛋白调节细胞存活或细胞凋亡、自噬和坏死性凋亡。关于朊病毒病中 DR 途径的激活，人们知之甚少。在正常小鼠脑中表达的 DR3 和 DR5 在朊病毒病中从未被研究过，因此也没有研究它们的配体和任何 DR 衔接蛋白。本研究旨在探讨这一研究空白。
用 Rocky Mountain Laboratory scrapie 小鼠朊病毒株感染 C57BL/6J 小鼠。通过观察形态和行为异常来检查朊病毒病的进展。使用基于抗体的技术测量 PrP 异构体和 GFAP 的水平，分别作为 PrP 积累和星形胶质细胞增生的标志物，该技术可在印迹和脑切片上检测蛋白质。DR 及其糖基化和细胞外结构域脱落以及相关因子的水平需要在蛋白质水平上进行检查，因此本研究采用了 Western blot 分析。
感染朊病毒的小鼠出现运动功能障碍和神经病理学改变，如 PrP 积累和星形胶质细胞增生，类似于其他朊病毒病。本研究结果表明，所有 DR 配体、TNFR1、Fas 和 p75NTR 的表达均升高，但 DR3 和 DR5 的水平降低。TRADD 和 TRAF2 等 DR 衔接蛋白（主要调节存活途径）的水平降低。主要调节细胞死亡的 FADD 水平保持不变。调节存活、凋亡和坏死性凋亡的 RIPK1 的表达和蛋白水解（抑制坏死性凋亡但激活凋亡）增加。
本研究首次提供了 DR3、DR5、DR6、TL1A、TRAIL、TRADD、TRAF2、FADD 和 RIPK1 参与朊病毒病的证据。本研究获得的知识讨论了这 16 种差异表达的 DR 因子对我们理解朊病毒病的多方面神经病理学以及对未来针对朊病毒病特异性神经病理学的潜在靶向治疗干预措施的可能影响。
