Microtubule–microtubule sliding by kinesin-1 is essential for normal cytoplasmic streaming in Drosophila oocytes

Significance Generation of mechanical forces by molecular motors is essential for development. Previously, we showed that the microtubule motor kinesin-1 generates forces by sliding microtubules against each other. Here, we show that microtubule sliding by kinesin-1 is important for normal oocyte cytoplasmic rotation, a process required for efficient localization of mRNAs and proteins during oogenesis. Using recently developed imaging technologies (Maple3 photoconversion and SunTag), we discover a previously uncharacterized population of extremely stable microtubules immobilized at the oocyte cortex and demonstrate that free microtubules move against cortically anchored microtubules, generating forces that contribute to cytoplasmic streaming. Because kinesin-1–based sliding is highly conserved fromDrosophila to humans, we propose that microtubule sliding is also important for cellular force generation in higher organisms.