SPEF2 functions in microtubule-mediated transport in elongating spermatids

Abstract

Sperm differentiation requires specific protein transport for correct sperm tail formation and head shaping. A transient microtubular structure, the manchette, appears around the differentiating spermatid head and serves as a platform for protein transport to the growing tail. Sperm flagellar protein 2 (SPEF2) is known to be essential for sperm tail development. In this study we investigated the function of SPEF2 during spermatogenesis using a male germ cell-specific Spef2 knockout mouse model. In addition to defects in sperm tail development, we observed a duplication of the basal body and failure in the manchette migration resulting in an abnormal head shape. We identified cytoplasmic Dynein 1 and GOLGA3 as novel interaction partners for SPEF2. SPEF2 and Dynein 1 colocalize in the manchette and the inhibition of Dynein 1 disrupts the manchette localization of SPEF2. Furthermore, the transport of a known SPEF2-binding protein IFT20 from the Golgi complex to the manchette was delayed in the absence of SPEF2. This data underline a possible novel role of SPEF2 as a linker protein for Dynein 1-mediated cargo transport along microtubules.