SPAG17 is Important for Protein Trafficking in Mammalian Spermiogenesis

Spermiogenesis is the process through which undifferentiated germ cells develop into mature spermatozoa. While spermiogenesis is a very well-regulated process, the protein-protein interactions regulating it remain poorly understood. A knockout (KO) mouse for the ciliary protein SPAG17 was generated by our lab. Loss of SPAG17 has been shown to disrupt the transport of proteins important for acrosome biogenesis and manchette functions. With this information, we hypothesized that SPAG17 plays an essential role in protein trafficking during mammalian spermiogenesis. To further investigate this, immunofluorescence (IF) studies were performed in germ cells collected from both WT and SPAG17 KO mice to visualize proteins of interest. Results showed GOPC, AZI1, KIF3A, INCENP, RAB6A and DDB1 to be missing from the manchette in the SPAG17 KO, suggesting they are part of the SPAG17 interactome of proteins. We then used IPA to map a possible interactome of proteins that may be regulated by SPAG17. Altogether, these findings reveal that SPAG17 is involved in the intracellular trafficking of proteins and it influences manchette formation, and thus acrosome and tail biogenesis in elongating spermatids by disturbing the recruitment of essential proteins to the manchette