title: Polymeric alkylpyridinium salts permit intracellular delivery of human Tau in rat hippocampal neurons: requirement of Tau phosphorylation for functional deficits.
abstract: Patients suffering from tauopathies including frontotemporal dementia (FTD) and Alzheimer's disease (AD) present with intra-neuronal aggregation of microtubule-associated protein Tau. During the disease process, Tau undergoes excessive phosphorylation, dissociates from microtubules and aggregates into insoluble neurofibrillary tangles (NFTs), accumulating in the soma. While many aspects of the disease pathology have been replicated in transgenic mouse models, a region-specific non-transgenic expression model is missing. Complementing existing models, we here report a novel region-specific approach to modelling Tau pathology. Local co-administration of the pore-former polymeric 1,3-alkylpyridinium salts (Poly-APS) extracted from marine sponges, and synthetic full-length 4R recombinant human Tau (hTau) was performed in vitro and in vivo. At low doses, Poly-APS was non-toxic and cultured cells exposed to Poly-APS (0.5 µg/ml) and hTau (1 µg/ml; ~22 µM) had normal input resistance, resting-state membrane potentials and Ca(2+) transients induced either by glutamate or KCl, as did cells exposed to a low concentration of the phosphatase inhibitor Okadaic acid (OA; 1 nM, 24 h). Combined hTau loading and phosphatase inhibition resulted in a collapse of the membrane potential, suppressed excitation and diminished glutamate and KCl-stimulated Ca(2+) transients. Stereotaxic infusions of Poly-APS (0.005 µg/ml) and hTau (1 µg/ml) bilaterally into the dorsal hippocampus at multiple sites resulted in hTau loading of neurons in rats. A separate cohort received an additional 7-day minipump infusion of OA (1.2 nM) intrahippocampally. When tested 2 weeks after surgery, rats treated with Poly-APS+hTau+OA presented with subtle learning deficits, but were also impaired in cognitive flexibility and recall. Hippocampal plasticity recorded from slices ex vivo was diminished in Poly-APS+hTau+OA subjects, but not in other treatment groups. Histological sections confirmed the intracellular accumulation of hTau in CA1 pyramidal cells and along their processes; phosphorylated Tau was present only within somata. This study demonstrates that cognitive, physiological and pathological symptoms reminiscent of tauopathies can be induced following non-mutant hTau delivery into CA1 in rats, but functional consequences hinge on increased Tau phosphorylation. Collectively, these data validate a novel model of locally infused recombinant hTau protein as an inducer of Tau pathology in the hippocampus of normal rats; future studies will provide insights into the pathological spread and maturation of Tau pathology.
authors.affiliation: School of Medical Sciences, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, UK.
authors.forename: Dave J
authors.initials: DJ
authors.lastname: Koss
authors.affiliation: School of Medical Sciences, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, UK.|Behavioural Neuroscience Core Facility, Division of Neuroscience, University of Dundee, Dundee, UK.
authors.forename: Lianne
authors.initials: L
authors.lastname: Robinson
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Mietelska-Porowska
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland.|Mossakowski Medical Research Centre, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Gasiorowska
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Kristina
authors.initials: K
authors.lastname: Sepčić
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Tom
authors.initials: T
authors.lastname: Turk
authors.affiliation: Department of Chemistry, Marine Biodiscovery Centre, University of Aberdeen, Aberdeen, UK.
authors.forename: Marcel
authors.initials: M
authors.lastname: Jaspars
authors.affiliation: Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland.
authors.forename: Grazyna
authors.initials: G
authors.lastname: Niewiadomska
authors.affiliation: School of Medical Sciences, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, UK.
authors.forename: Roderick H
authors.initials: RH
authors.lastname: Scott
authors.affiliation: School of Medical Sciences, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, UK.
authors.forename: Bettina
authors.initials: B
authors.lastname: Platt
authors.affiliation: School of Medical Sciences, University of Aberdeen, Foresterhill, AB25 2ZD, Aberdeen, UK. g.riedel@abdn.ac.uk.
authors.forename: Gernot
authors.initials: G
authors.lastname: Riedel
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004594:Electrophysiology / Q000379:methods; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007859:Learning Disabilities / Q000188:drug therapy; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation; D011108:Polymers / Q000008:administration & dosage* / Q000494:pharmacology; D011726:Pyridinium Compounds / Q000008:administration & dosage* / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D024801:Tauopathies / Q000378:metabolism; D016875:tau Proteins / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D011108:Polymers; D011726:Pyridinium Compounds; D011994:Recombinant Proteins; C115254:poly-APS; D016875:tau Proteins
keywords: Alzheimer’s disease; Calcium; Frontotemporal dementia; LTP; Phospho-Tau; Poly-APS; Tau; Tauopathies