Delta and epsilon tubulin in mammalian development

Delta (6-) and epsilon (epsilon-) tubulin are lesser-known cousins of alpha (alpha-) and beta (beta-) tubulin. They are likely to regulate centriole function in a broad range of species; however, their in vivo role and mechanism of action in mammals remain mysterious. In unicellular species and mammalian cell lines, mutations in 6- and epsilon-tubulin cause centriole destabilization and atypical mitosis and, in the most severe cases, cell death. Beyond the centriole, 6- and epsilon-tubulin localize to the manchette during murine spermatogenesis and interact with katanin-like 2 (KATNAL2), a protein with microtubule (MT)-severing properties, indicative of novel non-centriolar functions. Herein we summarize the current knowledge surrounding 6- and epsilon-tubulin, identify pathways for future research, and highlight how and why spermatogenesis and embryogenesis are ideal systems to define 6- and epsilon-tubulin function in vivo.