Reproductive and Developmental Medicine (Jan 2018)

Monoclonal antibodies reveal novel localization of SPAG11E in spermatozoa and the antifertility potential of SPAG11E motifs

  • Zhi-Kai Wang,
  • Yi-Ting Yang,
  • Xin-Yu Chen,
  • Shuang-Gang Hu,
  • Ping Zhu,
  • Wan-Xiang Xu,
  • Li Ma,
  • He-Guo Yu,
  • Hua Diao,
  • Yong-Lian Zhang

DOI
https://doi.org/10.4103/2096-2924.249890
Journal volume & issue
Vol. 2, no. 4
pp. 191 – 200

Abstract

Read online

Objective: SPAG11E is the first β-defensin that has been reported to activate Ca2+ uptake and sperm motility. However, the exact subcellular localization and interaction of SPAG11E with sperm remain controversial because of the lack of qualified antibody tools. SPAG11E is also a potential male antifertility target because SPAG11E fragment conjugated with a carrier protein exhibits male contraceptive vaccine potential. However, the fine B-cell epitope motifs of SPAG11E have not been analyzed, which hampered further exploration of the potential target. Methods: Polyclonal and monoclonal antibodies (mcAbs) of mature SPAG11E were raised and qualified with Western blotting. Subcellular localization of SPAG11E was revealed by Western blotting, immunohistochemistry staining, and electron microscopy. B-cell epitopes of rat SPAG11E were mapped by Western blotting using polyclonal and mcAbs. Based on the conservation of the identified epitope motifs between rat and mouse SPAG11E, antifertility potential of the epitope motifs was evaluated by the offspring of the males compromised with specific mcAbs. Results: SPAG11E antibodies of high quality were obtained and all B-cell epitope motifs of rat SPAG11E were mapped, in which conserved epitope motifs of SPAG11E in various species were discovered. The epitope motifs recognized by mcAbs were identified respectively. With mcAbs, rat SPAG11E was proved to be expressed in the caput region of epididymis. A novel finding was that SPAG11E was located in the flagella and nuclei of sperm as revealed by immunoelectron microscopy. In addition, the males treated with mcAbs (3#-1 and 10#B4) showed apparently fewer offspring. Conclusions: SPAG11E revealed a β-defensin with novel localization in sperm flagellum and nucleus with qualified antibodies. All B-cell epitope motifs of rat SPAG11E were determined, and the antifertility potential was proved by corresponding mcAbs.

Keywords