IMSATED   26825
INSTITUTO MULTIDISCIPLINARIO DE SALUD, TECNOLOGIA Y DESARROLLO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Generation of electrical oscillations by different microtubule structures.
Autor/es:
PEREZ PL; CANTIELLO HF; VILLA ETCHEGOYEN C; CANTERO MR; SCARINCI N
Lugar:
San Francisco, California
Reunión:
Congreso; 62th Annual Meeting of the Biophysical Society; 2018
Resumen:
Microtubules (MTs) are unique components of the cytoskeleton formed by hollow cylindrical structures of  tubulin dimeric units. MTs form intracellular superstructures of variable complexity and defined biological role(s) in cell function. MTs are able to amplify and axially transfer electrical signals, thus behaving as macromolecular transistors. However, the molecular aspects of these electrical signals are yet to be disclosed. We applied the patch clamp technique to different MT superstructures, including two-dimensional MT sheets and macrotubes, to characterize their electrical properties. Brain MTs were isolated from either rat or cow brains by polymerization-depolymerization cycles. MT sheets were particularly amenable to voltage-clamping as gigaseal formation was achieved in most cases. Electrically-biased MTs generated highly regular cation-selective oscillatory currents whose magnitude depended on the holding potential, ionic composition and ionic strength. Oscillations progressed through various regimes, including single and double periods, and more complex behaviors, being prominent a fundamental frequency at 29 Hz (in MT sheets but not macrotubes). In physiological K+ (140 mM), oscillations represented a 700% change in conductance. Interestingly, the peak conductance at 29 Hz obtained from the Fourier spectra, also showed strong nonlinearity, and a clear negative resistance region that was modeled with the Esaki diode current equation displaying a ?tunneling? effect. Current injection to MTs also induced voltage oscillations similar to action potentials. The electrical oscillations were entirely blocked by taxol, with pseudo Michaelis-Menten kinetics (KD = 1.29 M). The findings demonstrate that MTs are capable of generating electrical signals and behave as electrical oscillators and amplifiers that may be relevant to the various biological features of the neuronal cytoskeleton.