Distinct Localization of Aurora A Kinase in Mouse Spermatozoa Suggests a Novel Role in Sperm Motility

Abstract

In this work, we investigated the interaction of the kinase Aurora A (AURKA) with protein phosphatase 1 (PP1) and its role in sperm flagella. In somatic cells, AURKA and protein phosphatase‐1 (PP1) interact to regulate cilia dynamics and cell division, however a role for this complex in male germ cells had not been shown previously. Primary cilia and flagella are post‐mitotic cellular organelles that extend from the cell membrane and function in signal transduction and motility, respectively. They are analogous structures with both containing a microtubule‐based axoneme. Although the mechanisms governing growth and maintenance of primary cilia are well understood, information regarding the molecular pathways responsible for sperm flagella biogenesis is limited. Based on the role of AURAK and PP1 in cilia and the functional conservation of cilia and flagella, we wanted to determine whether this protein complex plays a role in flagella. Because AURKA is a binding partner of PP1, we investigated whether AURKA interacts with PP1g2, a testis specific isoform of PP1 involved in the initiation of motility. Coimmunoprecipitation experiments provided evidence of an interaction between PP1g2 and AURKA in adult mouse testes. We used indirect immunofluorescent to determine that AURKA localizes to spermatogonia, a finding consistent with its known role in formation of the mitotic spindle. We also detected AURKA in the flagella of spermatids within the lumen of seminiferous tubules prior to spermiation. Most notably, AURKA was localized to the flagella of spermatozoa. AURKA localized to the principal piece of epididymal sperm while activated AURKA (phospo‐Th288) localized to the midpiece of sperm flagellum. In order to determine whether the activity of AURKA changed during maturation of sperm in the epididymis, we quantified the activation of AURKA in sperm collected from the caput, corpus and cauda epididymis. Activated AURKA is enriched in the cauda epididymis where motile sperm reside. Results obtained from this study suggest a novel role for AURKA in the signaling pathway controlling sperm motility through an interaction with PP1.Support or Funding InformationThe work is supported by grant HD08051 Eunice Kennedy Shriver National Institute for Chile Health and Human DevelopmentThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.