Successful fertilization requires gametes to complete several stages, beginning with maturation and transport along the male and female reproductive tracts and ending with the interaction between the sperm and the egg. This last step involves sperm–egg adhesion and membrane fusion. ADAMs (disintegrin and metalloprotease domain proteins) are a family of membrane-anchored glycoproteins that are thought to play diverse roles in cell–cell adhesion through their interaction with integrins. This study analyzes the presence, location, processing, and possible role of ADAM15 in mouse sperm. The presence of ADAM15 in mouse spermatozoa was detected by Western blotting, which revealed that ADAM15 is post-translationally processed, during epididymal sperm maturation and the acrosome reaction. The 35 kDa antigen present in the acrosome-reacted sperm is the last proteolytic product of the 110/75 kDa ADAM15 found in non-capacitated sperm. This 35 kDa protein contains the disintegrin domain. By indirect immunofluorescence, ADAM15 was identified in the acrosomal region and along the flagellum of mouse spermatozoa. In acrosome-reacted sperm, ADAM15 was lost from the acrosomal region, but remained diffusely distributed throughout the head and flagellum. Furthermore, the ADAM15 disintegrin domain (RPPTDDCDLPEF) partially inhibited fusion and almost completely inhibited sperm–oolemma adhesion. In conclusion, our data indicate that ADAM15 is present in the testis and in spermatozoa from the caput, corpus, and cauda epididymis, as well as in non-capacitated and acrosome-reacted gametes. Results also indicate that ADAM15 is processed during epididymal maturation and acrosome reaction and that it may play a role during sperm–egg binding.
Karina Pastén-Hidalgo, Rosaura Hernández-Rivas, Ana Lilia Roa-Espitia, Manuel Sánchez-Gutiérrez, Francisco Martínez-Pérez, Alma Olivia Monrroy, Enrique O Hernández-González and Adela Mújica
Vitor Braga Rissi, Werner Giehl Glanzner, Mariana Priotto de Macedo, Lady Katerine Serrano Mujica, Karine Campagnolo, Karina Gutierrez, Alessandra Bridi, Hernan Baldassarre, Paulo Bayard Dias Gonçalves and Vilceu Bordignon
Insufficient epigenetic reprogramming is incompatible with normal development of embryos produced by somatic cell nuclear transfer (SCNT), but treatment with histone deacetylases inhibitors (HDACi) enhances development of SCNT embryos. However, the mechanisms underpinning HDACi benefits in SCNT embryos remain largely uncharacterized. We hypothesized that, in addition to enhancing reprogramming, HDACi treatment may promote expression of genes not required for early development of SCNT embryos. To test this hypothesis, RNA synthesis was inhibited by treating bovine SCNT embryos with 5,6-dichlorobenzimidazole 1-β-D-ribofuranoside (DBR), which were concomitantly treated or not with Scriptaid (Scrip; an HDACi). Development to the blastocyst stage was significantly increased by treatment with Scrip alone (26.6%) or associated with DRB (28.6%) compared to Control (17.9%). The total number of nuclei was significantly improved only in embryos that were treated with both Scrip + DRB. Nuclear decondensation after SCNT was significantly increased by DRB treatment either alone or associated with Scrip. The relative mRNA expression, evaluated during the embryo genome activation (EGA) transition, revealed that some KDMs (KDM1A, KDM3A, KDM4C and KDM6A) and DNMT1 where prematurely expressed in Scrip-treated embryos. However, treatment with Scrip + DRB inhibited early mRNA expression of those genes, as well as several other KDMs (KDM4A, KDM4B, KDM5A, KDM5B, KDM5C and KDM7A) compared to embryos treated with Scrip alone. These findings revealed that HDACi improved development in SCNT embryos compared to Control, but altered the expression of genes involved in epigenetic regulation and did not improve embryo quality. Inhibition of RNA synthesis during HDACi treatment enhanced nuclear chromatin decondensation, modulated gene expression and improved SCNT embryo quality.