Biology subjects

Congdon, E. E.

Publications and source records attributed to Congdon, E. E..

5 recordsLinked to original sources

bioRxiv2026

A single-domain antibody targets aggregation-prone region of α-synuclein to reduce synucleinopathy, rescue neurodegeneration and improve function

Synucleinopathies are a group of neurodegenerative disorders characterized by the accumulation of aggregated -synuclein (-syn), including Parkinsons disease, Dementia with Lewy Bodies, and Multiple System Atrophy. These diseases are marked by locomotor and non-motor impairments, as well as mitochondrial dysfunction and the loss of dopaminergic (DA) neurons. We have developed several anti--syn single-domain antibodies (sdAbs) and demonstrated the diagnostic imaging potential of two of them and the acute therapeutic benefit of one in clearing -syn in a mouse model. However, whether these sdAbs can suppress -syn-mediated neuronal loss and locomotor impairment in vivo remains unclear. We evaluated the therapeutic potential of five anti--syn sdAbs to clear pathological -syn in mouse neuronal culture and then demonstrated their in vivo efficacy in a Drosophila model of synucleinopathy. The sdAbs differed in their efficacy to lower levels of phospho-serine 129 -syn, prevent loss of DA neurons, alleviate mitochondrial dysfunction, improve motor function, and prolong survival in synucleinopathy flies. The most effective sdAb, 2H1, has not been reported before. It binds strongly to the aggregation prone region of -syn and robustly improves all these disease parameters. Additionally, that sdAb is associated with -syn in the fly neurons, as shown through proximity dependent turboID biotinylation assays. The sdAb-turboID also biotinylated -syn-associated proteins involved in synapse/vesicle trafficking pathways, pinpointing the location of their intracellular interaction. Our findings provide an insight into the therapeutic mechanism of action of these sdAbs and strongly support their clinical development.

neuroscience↗

bioRxiv2026

Tau pSer396 and pSer404 Define Distinct Epitope Regions Linked to Different Antibody Functions

Hyperphosphorylated tau is a central pathological feature of Alzheimers disease and related tauopathies, and antibodies targeting the pSer396/pSer404 epitope region represent a promising therapeutic strategy. However, direct comparisons of pSer396- and pSer404-selective antibodies and the impact of humanization on their functional properties remain limited. We generated two new monoclonal antibodies (mAbs), 9E (pSer404-specific) and G10 (pSer396-specific), and evaluated them alongside 4E6 (pSer404) and PHF-1 (pSer396) in murine and partially humanized chimeric formats. Antibodies were assessed in mixed cortical cultures using extracellular (PHF + Ab) and intracellular (PHF [->] Ab) paradigms. Efficacy in preventing tau-induced toxicity and seeding differed substantially among antibodies and was variably altered by chimerization, despite identical variable regions. Antibodies targeting pSer404 were more effective than those targeting pSer396, and antibodies that preferentially bound soluble pathological tau species in competition ELISA were consistently more efficacious, whereas neuronal uptake was comparable across variants. To define structural determinants of phospho-epitope recognition, we determined the crystal structures of the Fab regions of 9E, G10, and PHF-1, and additionally solved the co-crystal structure of Fab PHF-1 in complex with a pSer396 tau peptide at 2.55 [A] resolution. The PHF-1 complex reveals a heavy-chain-dominant binding mode in which pSer396 is anchored within an electropositive pocket and Tyr394 adopts a flipped conformation that stabilizes a {beta}-strand-like motif, consistent with a phosphorylation-dependent conformational switch. These findings demonstrate that epitope selectivity, aggregate preference, structural binding mode, and Fc context collectively govern antibody efficacy, and that humanization can substantially alter therapeutic properties.

neuroscience↗

bioRxiv2025

Single-Domain Antibody-Based Autophagosome-Targeting Chimera for Tau Clearance and Motor Function Restoration in Tauopathies

Tauopathies are neurodegenerative diseases characterized by pathological tau accumulation, leading to motor and neuropsychiatric symptoms. Effective tau-targeting therapies remain a major challenge. Here, we present 1D9-LIR{Delta}TP53INP2, a single-domain antibody (sdAb)-based protein degrader that facilitates tau clearance via the autophagy-lysosomal pathway. This engineered molecule combines the anti-tau sdAb 1D9 with an LC3-interacting region (LIR{Delta}TP53INP2) to promote autophagosomal recruitment, mimicking autophagy receptors by simultaneously binding tau and LC3. In frontotemporal dementia (FTD) patient-derived neurons and JNPL3 tauopathy mice, both harboring the P301L tau mutation, 1D9-LIR{Delta}TP53INP2 significantly reduced tau levels and improved motor function in mice. These findings underscore the therapeutic potential of sdAb-based protein degraders for tauopathies. Given the challenges of brain delivery for conventional antibodies, sdAbs with enhanced brain penetration and efficacy offer a promising strategy for treatment of neurodegenerative diseases.

neuroscience↗

bioRxiv2024

Clearing truncated tau protein restores neuronal function and prevents microglia activation in tauopathy mice

Tau protein truncated at aspartate 421 (Asp421) is a characteristic feature of Alzheimers disease (AD) and other tauopathies. It is likely to have a role in their pathogenesis by promoting tau aggregation. Here, using two tauopathy mouse models, we show that a monoclonal antibody against Asp421, 5G2, led to a) a 59-74% clearance of insoluble tau protein in the brains of JNPL3 tauopathy mice following a thirteen-week treatment period, b) a 46% decrease of tau levels in brain interstitial fluid immediately following a single dose of 5G2 as examined by brain microdialysis in awake JNPL3 mice, c) improved neuronal function and d) reduced microglial activation as determined by two-photon imaging in awake PS19 tauopathy mice, where we also found tau accumulation earlier than signs of microglial activation. For mechanistic insight using culture models, 5G2 prevented toxicity of AD brain-derived pathological tau protein, cleared intracellular tau, and prevented microgliosis. We also knocked down the intracellular Fc receptor and ubiquitin E3 ligase, TRIM21, and found a reduction in cellular retention of tau antibodies, which appeared to reduce the acute efficacy (24 h) of tau antibodies but not their longer-term efficacy (5 days). Overall, these findings strongly support the feasibility of targeting Asp421 truncated tau protein to treat tauopathies, indicate that tau-associated abnormalities of neuronal activity precede microglial activation and that antibody-mediated tau clearance via the TRIM21 pathway is mostly transient.

neuroscience↗

bioRxiv2024

Single-Domain Antibody-Based Protein Degrader for Synucleinopathies

Synucleinopathies are a group of neurodegenerative diseases characterized by the accumulation of -synuclein (-syn) in the brain, leading to motor and neuropsychiatric symptoms. Currently, there are no known cures for synucleinopathies, and treatments mainly focus on symptom management. In this study, we developed a single-domain antibody (sdAb)-based protein degrader with features designed to enhance proteasomal degradation of -syn. This sdAb derivative targets both -syn and Cereblon (CRBN), a substrate-receptor for the E3-ubiquitin ligase CRL4CRBN, and thereby induces -syn ubiquitination and proteasomal degradation. Our results indicate that this therapeutic candidate enhances proteasomal degradation of -syn, in addition to the endogenous lysosomal degradation machinery. By promoting proteasomal degradation of -syn, we improved clearance of -syn in primary culture and mouse models of synucleinopathy. These findings indicate that our sdAb-based protein degrader is a promising therapeutic candidate for synucleinopathies. Considering that only a small percentage of antibodies enter the brain, more potent sdAbs with greater brain entry than whole antibodies could enhance clinical benefits of antibody-based therapies.

neuroscience↗