Genome-wide mapping of unselected transcripts from extraembryonic tissue of 7.5-day mouse embryos reveals enrichment in the t-complex and under-representation on the X chromosome.
Mammalian embryos can only survive if they attach to the uterus (implantation) and establish proper maternal-fetal interactions. To understand this complex implantation pathway, we have initiated genomic analysis with a systematic study of the cohort of genes expressed in extraembryonic cells that are derived from the conceptus and play a major role in this process. A total of 2103 cDNAs from the extraembryonic portion of 7.5-day post-conception mouse embryos yielded 3186 expressed sequence tags, approximately 40% of which were novel to the sequence databases. Furthermore, when 155 of the cDNA clones with no homology to previously detected genes were genetically mapped, apparent clustering of these expressed genes was detected in subregions of chromosomes 2, 7, 9 and 17, with 6.5% of the observed genes localized in the t-complex region of chromosome 17, which represents only approximately 1.5% of the mouse genome. In contrast, X-linked genes were under-represented. Semi-quantitative RT-PCR analyses of the mapped genes demonstrated that one third of the genes were expressed solely in extraembryonic tissue and an additional one third of the genes were expressed predominantly in the extraembryonic tissues. The over-representation of extraembryonic-expressed genes in dosage-sensitive autosomal imprinted regions and under-representation on the dosage-compensated X chromosome may reflect a need for tight quantitative control of expression during development.
Ko
M S
MS
Center for Molecular Medicine and Genetics and Department of Internal Medicine, Wayne State University School of Medicine, 5047 Gullen Mall, Detroit, MI 48202, USA. msko@cmb.biosci.wayne.edu
Threat
T A
TA
Wang
X
X
Horton
J H
JH
Cui
Y
Y
Wang
X
X
Pryor
E
E
Paris
J
J
Wells-Smith
J
J
Kitchen
J R
JR
Rowe
L B
LB
Eppig
J
J
Satoh
T
T
Brant
L
L
Fujiwara
H
H
Yotsumoto
S
S
Nakashima
H
H
D000818:Animals; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D003627:Data Interpretation, Statistical; D004475:Ectoderm / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000378:metabolism*; D005314:Embryonic and Fetal Development / Q000235:genetics*; D020224:Expressed Sequence Tags; D005260:Female; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D015723:Gene Library; D005796:Genes / Q000235:genetics; D005819:Genetic Markers; D016678:Genome; D005865:Gestational Age; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D044767:Ubiquitin-Protein Ligases; D014960:X Chromosome / Q000235:genetics*; D056427:t-Complex Genome Region
D018076:DNA, Complementary; D005819:Genetic Markers; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; C116196:PPP1R11 protein, human; D044767:Ubiquitin-Protein Ligases