NCBI Summary:
This gene encodes a member of the sirtuin family of proteins, homologs to the yeast Sir2 protein. Members of the sirtuin family are characterized by a sirtuin core domain and grouped into four classes. The functions of human sirtuins have not yet been determined; however, yeast sirtuin proteins are known to regulate epigenetic gene silencing and suppress recombination of rDNA. Studies suggest that the human sirtuins may function as intracellular regulatory proteins with mono-ADP-ribosyltransferase activity. The protein encoded by this gene is included in class III of the sirtuin family. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq]
General function
, Epigenetic modifications
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Early embryo development
Comment
Expression regulated by
Comment
Ovarian localization
Oocyte
Comment
Sirt3 protects in vitro-fertilized mouse preimplantation embryos against oxidative stress-induced p53-mediated developmental arrest. Kawamura Y et al. Sirtuins are a phylogenetically conserved NAD+-dependent protein deacetylase/ADP-ribosyltransferase family implicated in diverse biological processes. Several family members localize to mitochondria, the function of which is thought to determine the developmental potential of preimplantation embryos. We have therefore characterized the role of sirtuins in mouse preimplantation development under in vitro culture conditions. All sirtuin members were expressed in eggs, and their expression gradually decreased until the blastocyst stage. Treatment with sirtuin inhibitors resulted in increased intracellular ROS levels and decreased blastocyst formation. These effects were recapitulated by siRNA-induced knockdown of Sirt3, which is involved in mitochondrial energy metabolism, and in Sirt3-/- embryos. The antioxidant N-acetyl-L-cysteine and low-oxygen conditions rescued these adverse effects. When Sirt3-knockdown embryos were transferred to pseudopregnant mice after long-term culture, implantation and fetal growth rates were decreased, indicating that Sirt3-knockdown embryos were sensitive to in vitro conditions and that the effect was long lasting. Further experiments revealed that maternally derived Sirt3 was critical. Sirt3 inactivation increased mitochondrial ROS production, leading to p53 upregulation and changes in downstream gene expression. The inactivation of p53 improved the developmental outcome of Sirt3-knockdown embryos, indicating that the ROS-p53 pathway was responsible for the developmental defects. These results indicate that Sirt3 plays a protective role in preimplantation embryos against stress conditions during in vitro fertilization and culture.