AT-rich repetitive DNA sequences, transcription frequency and germ layer determination.
Non-coding sequences of frog embryo endoderm poly (A+) nuclear RNA are AU-enriched, as compared to those of ectoderm and mesoderm. Endoderm blastomeres contain much less H1 histone than is present in ectoderm and mesoderm. H1 histone preferentially binds AT-rich DNA sequences to repress their transcription. The AT-enrichment of non-coding DNA sequences transcribed into poly (A+) nuclear RNA, as well as the low amount of H1 histone, may contribute to the higher transcription frequency of mRNA of endoderm, as compared to that of ectoderm and mesoderm. A greater accumulation of H1 histone in presumptive mesoderm and ectoderm may prevent transcription of endoderm specifying genes in mesoderm and ectoderm. Experimental upregulation of various transcription factors (TFs) can redirect germ layer fate. Most of these TFs bind AT-rich consensus sequences in DNA, suggesting that H1 histone and TFs active during germ layer determination are binding similar sequences.
Emeritus Department, Biological Sciences State University of New York at Buffalo, Buffalo, N.Y. 14260, USA. Electronic address: insleebaldwin@yahoo.com.
Reed
R
Flickinger
D020856:AT Rich Sequence; D000818:Animals; D001482:Base Composition; D001665:Binding Sites / Q000235:genetics; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000235:genetics* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005855:Germ Layers / Q000196:embryology* / Q000378:metabolism*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D014157:Transcription Factors / Q000378:metabolism; D014981:Xenopus / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism
D002843:Chromatin; D012333:RNA, Messenger; D038621:Regulatory Sequences, Ribonucleic Acid; D014157:Transcription Factors; D029867:Xenopus Proteins; D004247:DNA
AT-rich DNA; Germ layer determination