US EPA

1378552 

Journal Article 

Antisense oligonucleotides against Hsp70-1 and 70-3 increase mouse embryonic sensitivity to arsenite-induced dysmorphogenesis in vitro 

Hunter, ES; Dix, D 

1996 

1 

Teratology
ISSN: 0040-3709
EISSN: 1096-9926 

DART/TER/95002792 

53 

2 

eng 

Many teratogens induce embryonic expression of stress proteins, including heat shock proteins (HSP). The inducible Hsp70-1 and 70-3 (i.e. HSP72) are two members of this large gene family. Whether these proteins function to cause or prevent dysmorphogenesis is unclear. An antisense oligonucleotide (AO70) complementary to the start codon of both Hsp70-1 and 70-3 mRNA was used to block inducible HSP70 synthesis. A nonsense oligonucleotide (NON) served as a negative control. The 15 mer oligonucleotides were phosphorothioated and contained four propyne-dU and propyne-dC bases. Oligonucleotides were complexed with lipofectamine and injected into the amniotic cavity of 3-6 somite staged CD1 mouse embryos and cultured for 26 hrs. Conceptuses were untreated or exposed to 2 uM arsenite 2 hrs after injection. Embryos injected with lipofectamine or 20 uM NON developed normally. 10 and 20 uM AO70 produced no increase in craniofacial defects. Embryos injected with 10 or 20 uM NON and exposed to 2 uM arsenite also showed no increase in defects. Following NON injection 3/30 untreated embryos exhibited neural tube defects (NTDs); 5/50 embryos NON injected and exposed to arsenite had NTDs. In contrast, injection with 10 uM AO70 plus 2 uM arsenite produced 36% NTDs and 20 uM AO70 plus arsenite 85% NTDs. Additionally, eye and first arch defects, characteristic As-induced effects, were increased following coadministration of AO70 and arsenite. These experiments suggest that HSP70-1 and 70-3 are involved in the prevention of toxicant-induced malformations.