bioRxiv | 2021
Truncating Tau Reveals Different Pathophysiological Actions of Oligomers in Single Neurons
Abstract
Tau protein is involved in maintaining the structural integrity of neurons. In tauopathies, including Alzheimer’s disease, tau forms oligomers, which can modulate neuronal function. Previously the introduction of oligomeric full-length human tau (aa 1-441; FL-oTau) into pyramidal neurons decreased whole-cell conductance, increased excitability and changed the action potential (AP) waveform. Introducing N-terminally truncated tau (aa 124-441; CFRAG) removed the effects on the AP waveform and input resistance but the increase in excitability remained. A hyperpolarising shift in spike threshold underlies this increase in excitability. The N-terminal fragment (aa 1-123; NFRAG) markedly increased input resistance and changed the AP waveform. Lower concentrations of NFRAG only changed the AP waveform. Thus the two truncations can recapitulate the effects of FL-oTau. To investigate underlying mechanisms, we recorded sodium currents and found that FL-oTau lowers the activation voltage and reduced the maximal conductance, consistent with the lower spike threshold and reduction in AP amplitude Graphic abstract