Understanding the role of myosin‐10 at the mitotic spindle (801.3)

Abstract

The proper formation and function of mitotic spindles are essential for any organism. Disruption of myosin‐10 (myo10), an actin‐based motor protein, has been shown to perturb mitotic spindle structure and function. Such an important role for a myosin at the mitotic spindle is surprising since spindles are microtubule‐based structures. It thus stands to reason that myo10 either directly or indirectly interacts with spindle microtubules. In support of a direct interaction, a microtubule‐binding domain (MTB) has been identified in the C‐terminal tail of Myo10, suggesting that myo10 can interact with both cytoskeletal polymers. Here we use a dominant negative approach to investigate the function of the MTB in myo10’s spindle function. In brief, mRNA encoding various fragments of the myo10 C‐terminal tail with either intact or altered MTB were injected into Xenopus laevis embryos, and the embryos were subsequently analyzed for protein expression and spindle phenotypes. Results indicate that protein fragments containing intact MTB function as dominant negatives and cause spindle phenotypes similar to myo10 depletion, while fragments that either excluded or contained a mutated MTB did not. This suggests that the MTB of myo10 plays a crucial role in myo10’s function at the mitotic spindle.