PARENT SESSION
GENE REGULATION AND FUNCTION IN THE REPRODUCTIVE AXIS
Kent
7:30 AM-10:00 AM

(378) CONDITIONAL GENE TARGETING STRATEGIES TO DISTINGUISH THE ROLES OF MATERNAL AND ZYGOTIC AP-2 EXPRESSION DURING EMBRYONIC DEVELOPMENT.

Winger, Quinton¹, Huang, Jian¹, Williams, Trevor¹, ¹ University of Colorado Health Sciences Center, Denver, CO

ABSTRACT- Previous studies have shown that AP-2 is an essential transcription factor supporting embryonic development. Mice homozygous for an AP-2 mutation usually die around 7.5 dpc and we have determined that AP-2 expression is required in the extraembryonic lineages but is not needed in the embryo proper. In addition to expression in the trophectodermal lineages, AP-2 transcripts have also been detected in developing oocytes. Thus, we wished to determine if there was a maternal component of AP-2 expression in the embryo, and if it had any role in pre-implantation mouse development. Our new studies show that AP-2 transcript is present in the unfertilized oocyte and throughout pre-implantation development. We next established a method to examine the timing of AP-2 maternal message degradation and zygotic gene activation. These experiments take advantage of a single base pair polymorphism in the AP-2 gene between two different strains of mice. In each strain, the polymorphism creates a specific restriction site that enables us to distinguish their RT-PCR products. Employing this strategy we have determined the timing of maternal message degradation and zygotic gene activation. To investigate the function of this maternal message we have recently generated a conditional AP-2 allele in which the DNA binding domain has been flanked by loxP sites. This floxed AP-2 allele can also be used to study if this gene is needed after 7.5dpc, specifically for development and/or function of the placenta - a tissue in which many potential target genes for AP-2 have been identified. We have analyzed our floxed allele in combination with the following established Cre recombinase expressing strains: ZP3-Cre, TNAP-Cre, and MORE-Cre. The ZP3-Cre transgene is expressed in maturing oocytes and allows us to investigate maternal effect. TNAP-Cre is expressed in the primordial germ cells and the labyrinthine region of the placenta and allows the investigation of maternal effect and placenta defects. MORE-Cre is expressed in the epiblast and generates adult mice that lack AP-2, thus providing a system that can be used to study multiple reproductive processes. These specific conditional gene knock-outs have allowed us to characterize in detail the important role of AP-2 during mouse embryo development.

KEY WORDS: AP-2 , pre-implantaion, placenta, maternal effect