Bae Yeeun, Venkat Harshini, Preveza Natalie, Ray W Keith, Helm Richard F, Jarome Timothy J
School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
Neuroscience. 2025 Aug 6;580:18-26. doi: 10.1016/j.neuroscience.2025.06.032. Epub 2025 Jun 14.
Cognitive decline with aging is a complex process involving multiple brain regions and molecular mechanisms. While the role of the canonical protein degradation function of the ubiquitin-proteasome system (UPS) has been well studied in the context of aging and age-associated memory loss, the non-proteolytic functions of ubiquitin activity remain poorly understood. Here, we investigated the role of lysine-63 (K63) polyubiquitination, the most abundant form of proteasome-independent ubiquitination, in aged rats, focusing on the hippocampus and amygdala, two brain regions reported to have cellular and molecular alterations with age that are associated with age-related memory loss. Using an unbiased proteomic approach, we observed a significant increase of K63 polyubiquitination in the hippocampus across the lifespan. Reducing K63 polyubiquitination in the hippocampus of aged male rats using the CRISPR-dCas13 RNA editing system enhanced contextual fear memory, while similar manipulations in middle-aged rats, which typically have normal memory, had no effect, emphasizing the age-dependent role of K63 polyubiquitination in memory formation. Conversely, the amygdala showed a consistent reduction of K63 polyubiquitination protein targets across the lifespan, and further reductions of K63 polyubiquitination improved memory retention in aged, but not middle-aged, male rats. Together, our findings reveal the dynamic and region-specific functions of K63 polyubiquitination in the brain aging process, providing novel insights into its contribution to age-associated memory decline.
认知能力随年龄增长而下降是一个复杂的过程，涉及多个脑区和分子机制。虽然泛素-蛋白酶体系统（UPS）的经典蛋白质降解功能在衰老和与年龄相关的记忆丧失背景下已得到充分研究，但泛素活性的非蛋白水解功能仍知之甚少。在此，我们研究了赖氨酸-63（K63）多聚泛素化（蛋白酶体非依赖性泛素化的最丰富形式）在老年大鼠中的作用，重点关注海马体和杏仁核，这两个脑区据报道随着年龄增长会发生细胞和分子改变，且与年龄相关的记忆丧失有关。使用一种无偏向性的蛋白质组学方法，我们观察到在整个生命周期中，海马体中K63多聚泛素化显著增加。使用CRISPR-dCas13 RNA编辑系统减少老年雄性大鼠海马体中的K63多聚泛素化可增强情境恐惧记忆，而在通常具有正常记忆的中年大鼠中进行类似操作则没有效果，这强调了K63多聚泛素化在记忆形成中的年龄依赖性作用。相反，杏仁核在整个生命周期中显示出K63多聚泛素化蛋白靶点持续减少，进一步减少K63多聚泛素化可改善老年雄性大鼠而非中年雄性大鼠的记忆保持。总之，我们的研究结果揭示了K63多聚泛素化在大脑衰老过程中的动态和区域特异性功能，为其对与年龄相关的记忆衰退的贡献提供了新的见解。
