Dix D J, Garges J B, Hong R L
Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
Mol Reprod Dev. 1998 Dec;51(4):373-80. doi: 10.1002/(SICI)1098-2795(199812)51:4<373::AID-MRD3>3.0.CO;2-E.
Mouse 70-kDa heat shock proteins Hsp70-1 and Hsp70-3 (Hsp70-1/3) are stress-inducible protein chaperones thought to protect embryonic cells and tissues from the effects of a wide range of environmental exposures. Hsp70-1/3 are expressed constitutively, and at times are stress-inducible during various stages of preimplantation embryogenesis. In order to elucidate the functions of constitutive and stress-inducible Hsp70 expression in mouse preimplantation embryos, the consequences of inhibiting expression with antisense oligonucleotides complementary to the mRNAs of hsp70-1 and hsp70-3 (A070-1/3) were evaluated. Transfection of preimplantation embryos (four-cell stage) with 2.5 microM A070-1/3 had no effect on in vitro blastocoel formation. However, transfection with 5 or 10 microM A070-1/3 reduced in vitro blastocyst development to 30% and 0%, respectively (approximately 90% control embryos developed to blastocyst). Thus constitutive expression of Hsp70-1/3 appears significant to preimplantation embryogenesis. Limiting expression of Hsp70-1/3 with 5 microM A070-1/3 also heightened embryo sensitivity to arsenic, resulting in less than 5% in vitro development to blastocyst in the presence of the subtoxic dose of 0.4 microM sodium arsenite. Whether the combined effect of A070-1/3 and arsenic is due to blocking inducible expression of the Hsp70s, or due to further reducing the amount of constitutively expressed Hsp70s available to the embryo is not known at this time. However, these results clearly indicate that some minimal amount of Hsp70-1 and/or Hsp70-3 is required for preimplantation embryogenesis, and that increasing the demand for Hsp70s by arsenic exposure heightens this requirement.
小鼠70 kDa热休克蛋白Hsp70 - 1和Hsp70 - 3（Hsp70 - 1/3）是应激诱导型蛋白伴侣，被认为可保护胚胎细胞和组织免受多种环境暴露的影响。Hsp70 - 1/3组成性表达，并且在植入前胚胎发育的各个阶段有时也可被应激诱导。为了阐明小鼠植入前胚胎中组成性和应激诱导型Hsp70表达的功能，评估了用与hsp70 - 1和hsp70 - 3（A070 - 1/3）mRNA互补的反义寡核苷酸抑制表达的后果。用2.5 microM A070 - 1/3转染植入前胚胎（四细胞期）对体外囊胚腔形成没有影响。然而，用5或10 microM A070 - 1/3转染分别将体外囊胚发育率降低至30%和0%（约90%的对照胚胎发育成囊胚）。因此，Hsp70 - 1/3的组成性表达对植入前胚胎发育似乎很重要。用5 microM A070 - 1/3限制Hsp70 - 1/3的表达也会提高胚胎对砷的敏感性，在存在0.4 microM亚砷酸钠的亚毒性剂量时，体外发育成囊胚的比例不到5%。目前尚不清楚A070 - 1/3和砷的联合作用是由于阻断了Hsp70s的诱导型表达，还是由于进一步减少了胚胎可利用的组成性表达Hsp70s的量。然而，这些结果清楚地表明，植入前胚胎发育需要一定量的Hsp70 - 1和/或Hsp70 - 3，并且砷暴露增加对Hsp70s的需求会提高这一要求。
