Amurrio Elvis, Patel Janvi H, Danaher Marie, Goodwin Madison, Kargbo Porschderek, Klimentova Eliska, Lin Sonia, Kelly Michy P
Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Center for Research on Aging, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Cells. 2025 Jun 13;14(12):897. doi: 10.3390/cells14120897.
PDE11A is a little-studied phosphodiesterase sub-family that breaks down cAMP/cGMP, with the PDE11A4 isoform enriched in the memory-related hippocampal formation. Age-related increases in PDE11A expression occur in human and rodent hippocampus and cause age-related cognitive decline of social memories. Interestingly, age-related increases in PDE11A4 protein ectopically accumulate in spherical clusters that group together in the brain to form linear filamentous patterns termed "PDE11A4 ghost axons". The biophysical/physiochemical mechanisms underlying this age-related clustering are not known. Here, we determine if age-related clustering of PDE11A4 reflects liquid-liquid phase separation (LLPS; biomolecular condensation), and if PDE11A inhibitors can reverse this LLPS. We show human and mouse PDE11A4 exhibit several LLPS-promoting sequence features, including intrinsically disordered regions, non-covalent pi-pi interactions, and prion-like domains that were particularly enriched in the N-terminal regulatory region. Further, multiple bioinformatic tools predict PDE11A4 undergoes LLPS. Consistent with these predictions, aging-like PDE11A4 clusters in HT22 hippocampal neuronal cells were membraneless spherical droplets that progressively fuse over time in a concentration-dependent manner. Deletion of the N-terminal intrinsically disordered region prevented PDE11A4 LLPS despite equal protein expression between WT and mutant constructs. 1,6-hexanediol, along with tadalafil and BC11-38 that inhibit PDE11A4, reversed PDE11A4 LLPS in HT22 hippocampal neuronal cells. Interestingly, PDE11A4 inhibitors reverse PDE11A4 LLPS independently of increasing cAMP/cGMP levels via catalytic inhibition. Importantly, orally dosed tadalafil reduced PDE11A4 ghost axons in old mouse ventral hippocampus by 50%. Thus, PDE11A4 exhibits the four defining criteria of LLPS, and PDE11A inhibitors reverse this age-related phenotype both in vitro and in vivo.
磷酸二酯酶11A（PDE11A）是一个研究较少的磷酸二酯酶亚家族，可分解环磷腺苷/环磷鸟苷（cAMP/cGMP），其中PDE11A4亚型在与记忆相关的海马结构中富集。在人类和啮齿动物的海马体中，PDE11A的表达会随着年龄增长而增加，并导致与年龄相关的社交记忆认知衰退。有趣的是，与年龄相关的PDE11A4蛋白增加会异位聚集在球形簇中，这些球形簇在大脑中聚集在一起形成线性丝状模式，称为“PDE11A4幽灵轴突”。这种与年龄相关的聚集背后的生物物理/物理化学机制尚不清楚。在这里，我们确定PDE11A4与年龄相关的聚集是否反映液-液相分离（LLPS；生物分子凝聚），以及PDE11A抑制剂是否可以逆转这种LLPS。我们发现人类和小鼠的PDE11A4表现出几个促进LLPS的序列特征，包括内在无序区域、非共价π-π相互作用以及在N端调节区域特别富集的朊病毒样结构域。此外，多种生物信息学工具预测PDE11A4会发生LLPS。与这些预测一致，HT22海马神经元细胞中类似衰老的PDE11A4簇是无膜球形液滴，随着时间的推移会以浓度依赖的方式逐渐融合。删除N端内在无序区域可阻止PDE11A4发生LLPS，尽管野生型和突变体构建体之间的蛋白质表达相同。1,6-己二醇以及抑制PDE11A4的他达拉非和BC11-38可逆转HT22海马神经元细胞中的PDE11A4 LLPS。有趣的是，PDE11A4抑制剂可独立于通过催化抑制增加cAMP/cGMP水平来逆转PDEl1A4 LLPS。重要的是，口服他达拉非可使老年小鼠腹侧海马体中的PDE11A4幽灵轴突减少50%。因此，PDE11A4表现出LLPS的四个定义标准，并且PDE11A抑制剂在体外和体内均可逆转这种与年龄相关的表型。
