The Eps15 Homology Domain protein-1 (EHD1) is an ATPase and key endocytic regulatory protein required for optimal receptor recycling, and primary ciliogenesis. Over the past decade, a central role for EHD1 has been identified in the fission of endosomes. Despite these findings, additional evidence has also pointed at a potential function of EHD1 in the regulation of microtubules. Herein, we demonstrate that EHD1 regulates the distribution of endosomes, and conversely, centrosome depletion alters EHD1 localization in cells. We show that endogenous EHD1 is found in a complex with various endogenous tubulins including TUBB3, TUBB1, α-tubulin and γ-tubulin, interactions that are independent of intact microtubules, and appear to be indirect. Depletion of key individual EHD1 interaction partners that are known to bind tubulin fail to impede EHD1-tubulin interactions, suggesting that either several proteins are capable of mediating EHD1's connection with microtubules, or that the bridging interaction partner remains to be identified. Functionally, EHD1 depletion leads to impaired microtubule regrowth and decreased end-binding protein displacement, suggesting a role for EHD1 in modulating microtubule plus-end dynamics. Finally, EHD1's role in microtubule regulation appears to be evolutionarily conserved, as single-cell stage C. elegans embryos with a dysfunctional EHD1/RME-1 protein displayed enhanced tubulin accumulation at metaphase spindle poles. Our findings strongly support a previously unaddressed role for EHD1 in microtubule regulation.
Ashraf et al. (Wed,) studied this question.