Temporal/spatial expression and efflux activity of ABC transporter, P-glycoprotein/Abcb1 isoforms and Bcrp/Abcg2 during early murine development

• Published in: Gene Expression Patterns 2006-10, Vol.6 (7), p.738-746
• Main Authors: Sawicki, Wojciech T., Kujawa, Marek, Jankowska-Steifer, Ewa, Mystkowska, Ewa T., Hyc, Anna, Kowalewski, Cezary
• Format: Article
• Language: English
• Subjects: ABC transporters; abcb1a, abcb1b, abcb2, abcg2 genes; Animals; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1 - genetics; ATP Binding Cassette Transporter, Subfamily B, Member 1 - metabolism; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Blastocyst - metabolism; Early postimplantation; Embryo, Mammalian - cytology; Embryo, Mammalian - metabolism; Embryonic Development - genetics; Female; Gene Expression Regulation, Developmental; Male; Mice; Microscopy, Fluorescence; Mouse; Organogenesis - genetics; Preimplantation; Protein Isoforms - genetics; Protein Isoforms - metabolism; Proximal embryonic endoderm polarity; Reverse Transcriptase Polymerase Chain Reaction; Rhodamine 123/Hoechst 33342 efflux
• ISSN: 1567-133X; 1872-7298
• DOI: 10.1016/j.modgep.2005.12.003

ABC transporters pump out from cells a large number of endo- and xenobiotics including signal molecules and toxins; they are molecular markers of stem/progenitor cells as well. Here, we present the study of temporal/spatial patterns of Abcb1 isoforms and Abcg2 transporter expression and efflux activity in pre- and early postimplantation murine embryos. We found in 2-cell embryos abcb1a, abcb1b and abcg2 mRNAs which were believed to be maternally inherited. The expression of abcb1b and abcg2 genes was found in blastocysts and in 7 days postcoitum (dpc) embryos, while in 9 dpc embryos beside of abcb1b/abcg2, the abcb1a gene was expressed. The abcb2 mRNA was detectable neither in pre- nor in postimplantation embryos. Moreover, we analysed temporal/spatial patterns of rhodamine 123/Hoechst 33342 efflux, which mirrors the ABC transporter phenotype, from individual cells of pre- and postimplantation murine embryos. The blastomeres of 2-, 4- and 8-cell embryos had efflux-inactive phenotype. Single, efflux-active cells emerged first in the morulae and their number increased in blastocyst inner cell mass. In 6 and 7 dpc embryos, all embryonic cells hold the efflux-active phenotype. Proximal embryonic endoderm of 6–8 dpc embryos contained two sub-domains: one consisted of efflux-active cells and another one of efflux-inactive cells reflecting polarity of an embryo. Between 7 and 8 dpc, at the onset of organogenesis, the vehement surge of efflux-inactive embryonic cells occurred, and their number increased in 9 dpc embryos, which consequently contained few efflux-active cells.