title: Mfn2 Affects Embryo Development via Mitochondrial Dysfunction and Apoptosis.
abstract: BACKGROUND
  Growth factors, energy sources, and mitochondrial function strongly affect embryo growth and development in vitro. The biological role and prospective significance of the mitofusin gene Mfn2 in the development of preimplantation embryos remain poorly understood. Our goal is to profile the role of Mfn2 in mouse embryos and determine the underlying mechanism of Mfn2 function in embryo development.
  
  
  METHODS
  We transfected Mfn2-siRNA into 2-cell fertilized eggs and then examined the expression of Mfn2, the anti-apoptotic protein Bcl-2, and the apoptosis-promoting protein Bax by Western blot. Additionally, we determined the blastocyst formation rate and measured ATP levels, mtDNA levels, mitochondrial membrane potential (ΔΨm), and apoptosis in all of the embryos.
  
  
  RESULTS
  The results indicate that the Mfn2 and Bcl-2 levels were markedly decreased, whereas Bax levels were increased in the T group (embryos transfected with Mfn2-siRNA) compared with the C group (embryos transfected with control-siRNA). The blastocyst formation rate was significantly decreased in the T group. The ATP content and the relative amounts of mtDNA and cDNA in the T group were significantly reduced compared with the C group. In the T group, ΔΨm and Ca(2+) levels were reduced, and the number of apoptotic cells was increased.
  
  
  CONCLUSIONS
  Low in vitro expression of Mfn2 attenuates the blastocyst formation rate and cleavage speed in mouse zygotes and causes mitochondrial dysfunction, as confirmed by the ATP and mtDNA levels and mitochondrial membrane potential. Mfn2 deficiency induced apoptosis through the Bcl-2/Bax and Ca(2+) pathways. These findings indicate that Mfn2 could affect preimplantation embryo development through mitochondrial function and cellular apoptosis.
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Department of General Surgery, Union Hospital, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Family Planning Research Institute, Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Wenpei
authors.initials: W
authors.lastname: Xiang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000032:analysis; D047108:Embryonic Development / Q000235:genetics*; D005260:Female; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014162:Transfection; D015053:Zygote / Q000166:cytology / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D051028:bcl-2-Associated X Protein; D000255:Adenosine Triphosphate; D020558:GTP Phosphohydrolases; C488751:Mfn2 protein, mouse; D002118:Calcium