Expression of Cold-Adapted β-Tubulins Confer Cold-Tolerance to Human Cellular Microtubules

Abstract

Isolated microtubule proteins from the cold-adapted fish, Atlantic cod (Gadus morhua), assemble at temperatures between 8 and 30°C, while avian and mammalian microtubules normally do not assemble at temperatures below 20°C. Tubulin, the main component in microtubules, is expressed as many isotypes. Microtubules with different isotype composition have been shown to have different dynamic properties in vitro. Our hypothesis was that cold-tolerance of microtubules is caused by tubulin isotypes that differ in the primary sequence compared to mammalian tubulins. Here we show that transfection of human HepG2 cells with cod β-tubulin induced cold-adaptation of the endogenous microtubules. Incorporation of one single tubulin isotype can induce cold-tolerance to cold-intolerant microtubules. Three cod β-tubulin isotypes were tested and two of these (β1 and β2) transferred cold-tolerance to HepG2 microtubules, thus not all cod β-tubulins were able to confer cold-stability.