The microtubule oscillator as a universal phenomenon

SCARINCI, MARÍA NOELIA; CARABAJAL, MONICA PATRICIA ANTONELLA; CANTERO, MARÍA DEL ROCÍO; CANTIELLO, HORACIO F.

Buenos Aires

Congreso; XLIX Reunión Anual de la Sociedad Argentina de Biofísica; 2021

Microtubules (MTs), formed of cylindrical arrays of αβ tubulins, are essential cytoskeletonelements of eukaryotic cells. Previous studies from our laboratory (Priel 2006, 2008)demonstrated the ability of MTs to act as biopolymer transistors that may underlie theproduction of electrical oscillations by different assemblies from the mammalian brain(Cantero 2016, 2018, 2019, 2020). Although its electrical behavior may have importantimplications in neuronal cell function, no information is available as to whether MTs fromnon-excitable cells may also share similar properties. Here, we explored and compared theability of LLC-PK1 renal epithelial cells MTs to produce electrical oscillations. Further, wecompared them with those of FtsZ, a prokaryote protein and evolutionary ancestor oftubulin.Tubulin from LLC-PK1 cells was isolated by polymerization and serial steps withultracentrifugation. FtsZ from E. coli was purified by (NH₄)₂SO₄ precipitation. Sampleswere assembled into 2D-sheets by incubation with a polymerization buffer and thensubjected to voltage-clamp under gigaseal conditions. Electrical recordings from outputcurrents were obtained and filtered using Clampfit 10.7, showing a complex oscillatorybehavior. Power spectra and EMD analysis were performed using MatLab (2019a).Both LLC-PK1 MT and FtsZ had a similar oscillatory regimen with frequency peaks at 39 Hzand 91-93 Hz, which correlates with brain MT frequency of 39 Hz. EMD analysis of thesignals showed 6-7 intrinsic modes (IMF) for all 2D sheets (brain n=15, LLC-PK1 n=4, FtsZn=3), disclosing more fundamental frequency peaks. In most cases (n=19), the first IMFhad a 91-93 Hz frequency and the second was at 38-39 Hz, revealing the predominanceof these frequencies in all samples.Data support the hypothesis of MTs electrical oscillatory behavior as a highly conservedevolutive phenomenon, preserving similarities between brain and renal epithelial cells,and even a tubulin-related bacterial protein.