Novel Pentameric Thiophene Derivatives for in Vitro and in Vivo Optical Imaging of a Plethora of Protein Aggregates in Cerebral Amyloidoses

Abstract

Molecular probes for selective identification of protein aggregates are important to advance our understanding of the molecular pathogenesis underlying cerebral amyloidoses. Here we report the chemical design of pentameric thiophene derivatives, denoted luminescent conjugated oligothiophenes (LCOs), which could be used for real-time visualization of cerebral protein aggregates in transgenic mouse models of neurodegenerative diseases by multiphoton microscopy. One of the LCOs, p-FTAA, showed conformation-dependent optical properties and could be utilized for ex vivo spectral assignment of distinct prion deposits from two mouse-adapted prion strains. p-FTAA also revealed staining of transient soluble pre-fibrillar non-thioflavinophilic Aβ-assemblies during in vitro fibrillation of Aβ peptides. In brain tissue samples, Aβ deposits and neurofibrillary tangles (NFTs) were readily identified by a strong fluorescence from p-FTAA and the LCO staining showed complete co-localization with conventional antibodies (6E10 and AT8), indicating that p-FTAA detects all the immuno-positive aggregated proteinaceous species in Alzheimer disease, but with significantly shorter imaging time (100 fold) compared to immunofluorescence. In addition, a patchy islet-like staining of individual Aβ plaque was unveiled by the anti-oligomer A11 antibody during co-staining with p-FTAA, suggesting that pre-fibrillar species are likely an intrinsic component of Aβ plaques in human brain. The major hallmarks of Alzheimer's disease, namely Aβ aggregates versus NFTs could also be distinguished due to distinct emission spectra from p-FTAA. Overall, we demonstrate that LCOs can be utilized as powerful practical research tools for studying protein aggregation diseases and facilitate the study of amyloid origin, evolution and maturation, Aβ−tau interactions and pathogenesis both ex vivo and in vivo. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptThe formation of highly ordered aggregates of intra-or extracellular proteins underlies a wide range of neurodegenerative conditions including prion, Parkinson's, Huntington's and Alzheimer's (AD) diseases. Hence, molecular probes that specifically target protein aggregates and allow in vitro or in vivo imaging of these pathological hallmarks, are of great importance. Small hydrophobic probes that cross the blood-brain barrier (BBB) can be monitored in vivo with positron emission tomography (PET), single-photon emission computerized tomography (SPECT) or multiphoton microscopy (1-7). The latter is especially applicable in transgenic mouse models where mechanistic insights regarding the pathological events involved in the formation of protein deposits can be obtained. Additionally, molecular imaging probes may also help in early diagnosis of neurodegenerative diseases and in monitoring the effect of therapeutic interventions. However, a major drawback of these conventional probes is that only a subset of aggregates that roughly corresponds to histologically identifiable amyloid ...

Reduction of Synaptojanin 1 Accelerates Aβ Clearance and Attenuates Cognitive Deterioration in an Alzheimer Mouse Model

“…pAb369 (C-terminal APP antibody) was used to detect human and mouse holo-APP and C-terminal fragments (8). The amyloid specific luminescent conjugated oligothiophene (LCO) was used for histological staining of the presence of amyloid deposits in combination with immunofluorescence (9). AB14 (N-terminal PS1 antibody) (10) was used to detect PS1.…”

Biochemical markers in early diagnosis and management of systemic amyloidoses

“…A novel class of amyloid ligands, luminescent-conjugated thiophene polymers (LCP), has recently been described [63,64]. These conformation-sensitive compounds interact with amyloid fibrils in tissue sections, and were shown to be highly sensitive for visualization of amyloid deposits.…”

Zinc-Triggered Hierarchical Self-Assembly of Fibrous Helix–Loop–Helix Peptide Superstructures for Controlled Encapsulation and Release

“…The oligothiophene p-FTAA 39 were kindly provided by the group of Peter Nilsson at Linköping University. All other chemicals were acquired from Sigma Aldrich (Sweden).…”

“…Addition of EDTA triggered the release of the encapsulated JR2EC-AuNPs, resulting in a blue shift (19 nm) of the localized surface plasmon (LSPR) band as the particles were resuspended (Figure 4c). To investigate the possibility to also encapsulate molecular compounds, two different fluorescent molecules, rhodamine-B (RhoB) and the thiophene-based conjugated oligomer p-FTAA ( Figure S5), 39 were added prior addition of Zn…”