Yunjong Lee

Parkinson's disease (PD) involves progressive degeneration of nigrostriatal ventral midbrain dopaminergic (vmDA) neurons and Lewy body proteopathy, necessitating scalable, lineage‐faithful donor cells. However, variability in human pluripotent stem cell (hPSC) differentiation and incomplete ventral midbrain identity limit translational use. Here, we establish a developmentally guided differentiation protocol that reproducibly specifies EN1‐positive vmDA progenitors through temporally optimized SHH, WNT/β‐catenin, and FGF8 signaling. The resulting progenitors mature into vmDA neurons exhibiting stimulus‐dependent dopamine release and maturation‐associated pacemaking activity. Progenitors can be cryopreserved at a defined stage while retaining viability and neurogenic capacity. Functional validation was performed using complementary proteopathy‐based PD models. In vitro, optogenetic induction of α‐synuclein aggregation ( OASIS ) triggered robust aggregate formation and selective degeneration of TH‐positive vmDA neurons in both two‐dimensional cultures and three‐dimensional neurospheroids. In vivo, we established a conditional β23 proteopathy‐based PD mouse model exhibiting progressive nigrostriatal degeneration and motor impairment. Transplantation of hESC‐derived vmDA progenitors into advanced‐stage PD mice led to graft survival, differentiation into vmDA neurons, and significant motor improvement. Together, these findings define a robust vmDA differentiation framework validated across proteopathy‐based disease modeling and transplantation contexts, supporting its application in PD modeling and cell therapy.

Lewy body dementia (LBD), encompassing Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB), is defined by widespread α-synuclein (αSyn) aggregation and frequently exhibits coexistent tau and amyloid-β (Aβ) pathologies. However, whether αSyn pathology is sufficient to drive endogenous tau and Aβ aggregation has remained unclear due to a lack of in vivo models that recapitulate the full spectrum of LBD-associated proteinopathies and neurodegeneration. AIMP2, a parkin substrate that accumulates in Parkinson’s disease, enhances αSyn aggregation and toxicity, but its role in initiating downstream mixed pathologies across vulnerable brain regions has not been demonstrated in vivo. Here, we generated a conditional, neuron-specific Tet-Off double-transgenic mouse model enabling post-developmental coexpression of AIMP2 and A53T αSyn. This synergistic coexpression induced rapid and widespread αSyn aggregation, detergent-insoluble Lewy-like inclusions, mitochondrial degeneration, synaptic impairment, and neuronal loss, accompanied by marked gliosis. Mice developed key clinical features of LBD, including progressive cognitive impairment, bradykinesia, and olfactory deficits. Notably, without tau or APP overexpression, endogenous tau became hyperphosphorylated through dysregulated kinase signaling, and Aβ accumulated predominantly as TBS-soluble Aβ42 monomers/oligomers without fibrillar plaque deposition, demonstrating that AIMP2–αSyn–driven pathology is sufficient to trigger downstream tauopathy and Aβ pathologies. These mixed pathologies were associated with lysosomal and proteasomal dysfunction, evidenced by p62 and polyubiquitinated protein accumulation. Proteomic analysis identified dysregulation of pathways linked to amyloid processing, synaptic trafficking, and protein quality control. Importantly, temporal suppression of AIMP2 and αSyn expression promoted reduction of pre-existing pathologies and partially restored cognitive function. This study establishes a genetically controlled in vivo model of LBD-like mixed proteinopathy recapitulating αSyn aggregation, tau hyperphosphorylation, Aβ accumulation, neurodegeneration, and behavioral decline. These findings support a mechanistic link between AIMP2-enhanced αSyn toxicity and secondary proteinopathies and position this model as a platform for mechanistic and therapeutic studies in complex α-synucleinopathies.

Resistance to 5-fluorouracil (5-FU) and oxaliplatin (OXA) remains an obstacle in colorectal cancer (CRC) therapy, but the upstream mechanisms enabling adaptive survival remain unclear. Angiomotin (AMOT), a Hippo-YAP regulator, is expressed as two major isoforms, p130 and p80, but the contribution of isoform-specific AMOT regulation to chemoresistance is unknown. RNA-seq of OXA-resistant cells identified AMOT as a candidate determinant, and its isoform-specific regulation and functional relevance were then examined in OXA- and 5-FU-resistant CRC sublines. AMOT-p80 was preferentially upregulated, whereas AMOT-p130 remained largely unchanged. Common AMOT pre-mRNA was elevated, whereas p130-specific pre-mRNA was unchanged, consistent with preferential transcriptional activation favoring the p80 isoform. Functionally, AMOT depletion minimally affected basal viability but significantly sensitized resistant cells to 5-FU or OXA, with increased apoptotic responses. AMOT silencing reduced nuclear YAP and lowered c-Myc and Cyclin D1 protein levels, whereas AMOT-p80 re-expression restored nuclear YAP, with recovery of c-Myc/Cyclin D1 levels and drug tolerance. YAP knockdown attenuated these outputs and blunted the additional effect of AMOT depletion. AMOT-p80 overexpression in parental cells increased c-Myc/Cyclin D1 protein levels and enhanced tolerance to 5-FU and OXA. These findings suggest that preferential AMOT-p80 upregulation is linked to YAP-associated chemoresistant phenotypes in CRC cells.

Background: The pathology of Lewy body dementia (LBD) features neuronal α-synuclein (α-syn) accumulation and astrocytic hyperactivation in cognitive brain circuits. Ultra-low-intensity ultrasound (ULIUS) modulates astrocyte function via transient receptor potential ankyrin 1 (TRPA1) and has been investigated for therapeutic applications in neurodegenerative diseases. Methods: The therapeutic efficacy and mechanisms of ULIUS were evaluated in primary cultured astrocytes and neuron-glia cocultures treated with α-syn preformed fibrils (PFFs), as well as in an LBD model induced by hippocampal α-syn PFF injection into neuronal α-syn-A53T transgenic mice. Astrocytic TRPA1 was modulated under pathologic conditions with ULIUS or a pharmacologic TRPA1 antagonist to determine calcium responses and transcriptional regulation of Trpa1 and inflammation-related genes. Neuropathological analyses for Lewy-like inclusions, neurodegeneration, and inflammation were performed in LBD mouse brains, with or without ULIUS. Spatial learning and memory were assessed using the Barnes maze. Results: Repeated transcranial ULIUS application was safe in long-term use and, unlike prolonged stronger ultrasound, did not cause hippocampal inflammation or neurodegeneration. It also prevented neuroinflammation and Lewy-like pathologies, rescuing cognitive impairment in LBD mice. ULIUS abolished α-syn-induced elevation of TRPA1, toll-like receptors-2 (TLR2), interleukin-1β, and tumor necrosis factor-α in LBD mouse brains. Mechanistically, both ULIUS and TRPA1 inhibitor blocked the sustained TRPA1-dependent calcium increase and the expression of inflammation-associated transcripts in α-syn PFF-treated astrocytes. Conclusions: Our findings provide mechanistic insights into the reciprocal TRPA1–TLR2 signaling pathway in α-syn-induced astrocyte pathology and underscore the disease-modifying potential of focused transcranial ULIUSm on astrocytes for the treatment of LBD. This study establishes a novel therapeutic strategy to alleviate neuroinflammation and cognitive decline associated with LBD. The demonstration of its long-term safety further supports ULIUS as a promising therapeutic strategy.

Objectives: Moyamoya disease (MMD) is a rare cerebrovascular disorder characterized by the progressive narrowing of arteries at the base of the brain, forming abnormal collateral vascular networks. While vascular parkinsonism is noted in MMD, its link to Parkinson's disease (PD) has not been explored. We aimed to determine whether the risk of PD is increased in patients with MMD and to identify the potential role of the RNF213 gene. Methods: We report two cases of PD with a history of MMD associated with the Arg4810Lys variant of RNF213 . Using the Korean National Health Insurance Service database, we studied the association between MMD and subsequent PD risk using Cox proportional hazards regression analysis. Moreover, we explored the interaction between α‐synuclein and RNF213 proteins by overexpressing SNCA and RNF213 in SH‐SY5Y cells. Furthermore, we confirmed the proximity of Lewy pathology and RNF213 proteins in postmortem brain tissues from three patients with PD and age‐matched controls. Results: Among 16,830 patients aged ≥ 40 with MMD, 3415 were enrolled, excluding those with prior PD or stroke, along with a matched control group of 33,974. The analysis revealed an increased PD risk in patients with MMD (hazard ratio = 4.45 [3.40–5.82], p < 0.0001). Overexpression of RNF213 resulted in cytoplasmic inclusions, which were worsened by the co‐expression of SNCA and the Arg4810Lys variant of RNF213. Histological studies confirmed the co‐localization of α‐synuclein aggregates and RNF213 proteins in PD brain tissues. Interpretation: This study confirms the heightened PD risk in patients with MMD and suggests a pathophysiological link through α‐synuclein and RNF213 interactions.

Parkinson’s disease (PD) is characterized by the selective degeneration of midbrain dopaminergic neurons and aggregation of α-synuclein. Emerging evidence implicates the gut microbiome in PD, with microbial metabolites proposed as potential pathological mediators. However, the specific microbes and metabolites involved, and whether gut-derived metabolites can reach the brain to directly induce neurodegeneration, remain unclear. Here we show that elevated levels of Streptococcus mutans (S. mutans) and its enzyme urocanate reductase (UrdA), which produces imidazole propionate (ImP), in the gut microbiome of patients with PD, along with increased plasma ImP. Colonization of mice with S. mutans harboring UrdA or Escherichia coli expressing UrdA from S. mutans increases systemic and brain ImP levels, inducing PD-like symptoms including dopaminergic neuronal loss, astrogliosis, microgliosis, and motor impairment. Additionally, S. mutans exacerbates α-synuclein pathology in a mouse model. ImP administration alone recapitulates key PD features, supporting the UrdA–ImP axis as a microbial driver of PD pathology. Mechanistically, mTORC1 activation is crucial for both S. mutans- and ImP-induced PD pathology. Together, these findings identify microbial ImP, produced via UrdA, as a direct pathological mediator of the gut-brain axis in PD.

Background: The parkin-interacting substrate (PARIS, also known as ZNF746) is a transcriptional repressor, whose accumulation and phosphorylation play central pathological roles in Parkinson’s disease (PD). PARIS-induced transcriptional repression of PGC-1α or MDM4 contributes to mitochondrial dysfunction and p53-dependent neuron loss in PD. Despite the important role of PARIS in PD pathogenesis, unbiased transcriptomic profiles influenced by PARIS accumulation in dopaminergic neurons remain unexplored. Methods: We engineered Tet-Off conditional transgenic mice expressing PARIS in dopaminergic neurons, driven by DAT-PF-tTA driver mice. The conditional PARIS transgenic mice were characterized by PD-associated pathologies, including progressive dopamine cell loss, neuroinflammation, PGC-1α repression, and mitochondrial proteome alteration. Motor impairment was assessed using pole and rotarod tests. L-DOPA and c-Abl inhibitors were administered to PARIS transgenic mice to evaluate their therapeutic efficacy. The transcriptomic profiles and gene ontology clusters were analyzed by bulk and single-nucleus RNA-seq for the ventral midbrains from PARIS transgenic and age-matched controls. Results: Conditional dopaminergic PARIS expression in mice led to the robust and selective dopaminergic neuron degeneration, neuroinflammation, and striatal dopamine deficits, resulting in L-DOPA-responsive motor impairments. Consistent with the results of previous reports, PARIS suppressed dopaminergic PGC-1α expression, disturbed mitochondrial marker protein expression, and reduced COXIV-labeled mitochondria in dopamine neurons. Pharmacological inhibition of c-Abl activity in PARIS transgenic mice largely prevents PD-associated pathological features. Unbiased transcriptomic analysis revealed PARIS-regulated differentially expressed genes (DEGs), both collectively and in a cell-type-specific manner, along with enriched biological pathways linked to PD pathogenesis. Single-cell resolution transcriptomic analysis confirmed repression of PGC-1α and several mitochondria-related target genes in dopaminergic cells. Additionally, we identified distinct glial cell subpopulations and DEGs associated with PD pathogenesis. Conclusions: Conditional PARIS transgenic mice recapitulate robust and dopaminergic neuron-selective pathological features of PD, allowing the preclinical evaluation of antisymptomatic and disease-modifying therapeutic strategies within a couple of months. Based on this new PD mouse model, we provide unbiased bulk and single-nucleus transcriptomic profiles that are regulated by PARIS and potentially contribute to PD pathogenesis. A PD mouse model with flexible pathology induction capacity and a whole transcriptome could serve as a useful resource for translational PD research.

Propagation of neuronal α-synuclein aggregate pathology to the cortex and hippocampus correlates with cognitive impairment in Parkinson’s disease (PD) dementia and dementia with Lewy body disease. Previously, we showed accumulation of the parkin substrate aminoacyl-tRNA synthetase interacting multifunctional protein-2 (AIMP2) in the temporal lobe of postmortem brains of patients with advanced PD. However, the potential pathological role of AIMP2 accumulation in the cognitive dysfunction of patients with PD remains unknown. We performed immunofluorescence imaging to examine cellular distribution and accumulation of AIMP2 in brains of conditional AIMP2 transgenic mice and postmortem PD patients. The pathological role of AIMP2 was investigated in the AIMP2 transgenic mice by assessing Nissl-stained neuron counting in the hippocampal area and Barnes maze to determine cognitive functions. Potential secretion and cellular uptake of AIMP2 was monitored by dot blot analysis and immunofluorescence. The utility of AIMP2 as a new PD biomarker was evaluated by dot blot and ELISA measurement of plasma AIMP2 collected from PD patients and healthy control followed by ROC curve analysis. We demonstrated that AIMP2 is toxic to the dentate gyrus neurons of the hippocampus and that conditional AIMP2 transgenic mice develop progressive cognitive impairment. Moreover, we found that neuronal AIMP2 expression levels correlated with the brain endothelial expression of AIMP2 in both AIMP2 transgenic mice and in the postmortem brains of patients with PD. AIMP2, when accumulated, was released from the neuronal cell line SH-SY5Y cells. Secreted AIMP2 was taken up by human umbilical vein endothelial cells. Consistent with the fact that AIMP2 can be released into the extracellular space, we showed that AIMP2 transgenic mice have higher levels of plasma AIMP2. Finally, ELISA-based assessment of AIMP2 in plasma samples from patients with PD and controls, and subsequent ROC curve analysis proved that high plasma AIMP2 expression could serve as a reliable molecular biomarker for PD diagnosis. The pathological role in the hippocampus and the cell-to-cell transmissibility of AIMP2 provide new therapeutic avenues for PD treatment, and plasma AIMP2 combined with α-synuclein may improve the accuracy of PD diagnosis in the early stages.

ZNF746 was identified as parkin-interacting substrate (PARIS). Investigating its pathophysiological properties, we find that PARIS undergoes liquid-liquid phase separation (LLPS) and amorphous solid formation. The N-terminal low complexity domain 1 (LCD1) of PARIS is required for LLPS, whereas the C-terminal prion-like domain (PrLD) drives the transition from liquid to solid phase. In addition, we observe that poly(ADP-ribose) (PAR) strongly binds to the C-terminus of PARIS near the PrLD, accelerating its LLPS and solidification. N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced PAR formation leads to PARIS oligomerization in human iPSC-derived dopaminergic neurons that is prevented by the PARP inhibitor, ABT-888. Furthermore, SDS-resistant PARIS species are observed in the substantia nigra (SN) of aged mice overexpressing wild-type PARIS, but not with a PAR binding-deficient PARIS mutant. PARIS solidification is also found in the SN of mice injected with preformed fibrils of α-synuclein (α-syn PFF) and adult mice with a conditional knockout (KO) of parkin, but not if α-syn PFF is injected into mice deficient for PARP1. Herein, we demonstrate that PARIS undergoes LLPS and PAR-mediated solidification in models of Parkinson's disease.