Evolutionarily conserved sperm factors, DCST1 and DCST2, are required for gamete fusion

Area of Science:

• Reproductive Biology
• Developmental Biology
• Evolutionary Biology

Background:

• Sperm-egg fusion is essential for fertilization, involving complex molecular interactions.
• Key proteins like sperm IZUMO1 and oocyte JUNO (IZUMO1R) are critical in mammals.
• No common factor regulating gamete fusion across vertebrates and invertebrates had been identified.

Purpose of the Study:

• To identify novel, evolutionarily conserved factors involved in mammalian sperm-egg fusion.
• To investigate the roles of DCST1 and DCST2 in the fertilization process.
• To understand the regulatory mechanisms of sperm factors like SPACA6.

Main Methods:

• Gene disruption and complementation experiments in mice.
• Analysis of protein stability and interactions of gamete fusion factors.
• Comparative evolutionary analysis of identified factors.

Main Results:

• Dendrocyte expressed seven transmembrane protein domain-containing 1 (DCST1) and DCST2 were confirmed as essential for sperm-egg fusion in mice.
• DCST1/2 and IZUMO1 were found to differentially regulate the protein stability of SPACA6.
• Evidence for an evolutionarily conserved system (nearly one billion years old) regulating gamete fusion was presented.

Conclusions:

• DCST1 and DCST2 are indispensable for mammalian fertilization, highlighting their conserved role.
• Spermatozoa utilize integrated molecular pathways, including ancient conserved systems, for successful fertilization.
• The findings expand our understanding of the molecular basis of reproduction and evolution.