Expression and role of c-myc protooncogene in murine preimplantation embryonic development.
OBJECTIVE
The present study was conducted to investigate the expression and possible role of the c-myc protooncogene in preimplantation embryos by using reverse-transcriptase/polymerase chain reaction (RT-PCR) technique and microinjection of synthetic antisense c-myc oligonucleotide probe, respectively. Total RNA was extracted from oocytes and two cell-, four cell-, early morula-, late morula-, early blastocyst-, and late blastocyst-stage embryos, and cDNA was constructed using MMLV reverse transcriptase. Sense primer (P1) and antisense primer (P2) used were based on the c-myc gene sequence bp 1609-1629 and bp 3279-3299, respectively, that span a 1.37-kb intron. PCR-amplified products of cDNA from oocyte-, two cell-, four cell-, early and late morula-, and blastocyst-stage embryos demonstrated the expected 313-bp product in Southern blot hybridization using a c-myc specific DNA probe, with an indication of lower levels in oocytes and early morulae.


RESULTS
Cytoplasmic injection of the antisense c-myc oligonucleotide probe (P2) and not the sense probe (P1) into pronuclear-stage zygotes caused a significant (P = 0.02 to 0.0001) inhibition of development to blastocysts in a concentration-dependent manner, with a maximal inhibition at the first cleavage of zygotes to two cell-stage embryos. There was no effect on the P2 antisense injection on pronucleus formation.


CONCLUSIONS
These results indicate that the c-myc protooncogene is expressed in preimplantation embryos and may have an essential role in normal embryogenesis in mice.
Naz
R K
RK
Department of Obstetrics and Gynecology, Albert Einstein College of Medicine, New York, New York 10461.
Kumar
G
G
Minhas
B S
BS
D000818:Animals; D001483:Base Sequence; D001755:Blastocyst / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D015139:Blotting, Southern; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D016259:Genes, myc / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D009865:Oocytes / Q000737:chemistry / Q000166:cytology / Q000502:physiology; D016133:Polymerase Chain Reaction; D016271:Proto-Oncogene Proteins c-myc / Q000032:analysis / Q000235:genetics / Q000502:physiology; D012313:RNA / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D013084:Sperm-Ovum Interactions; D015053:Zygote / Q000737:chemistry / Q000166:cytology / Q000502:physiology
D017931:DNA Primers; D016376:Oligonucleotides, Antisense; D016271:Proto-Oncogene Proteins c-myc; D012313:RNA