The Regulation of rRNA Gene Transcription during Directed Differentiation of Human Embryonic Stem Cells.
It has become increasingly clear that proper cellular control of pluripotency and differentiation is related to the regulation of rRNA synthesis. To further our understanding of the role that the regulation of rRNA synthesis has in pluripotency we monitored rRNA synthesis during the directed differentiation of human embryonic stem cells (hESCs). We discovered that the rRNA synthesis rate is reduced ~50% within 6 hours of ACTIVIN A treatment. This precedes reductions in expression of specific stem cell markers and increases in expression of specific germ layer markers. The reduction in rRNA synthesis is concomitant with dissociation of the Pol I transcription factor, UBTF, from the rRNA gene promoter and precedes any increase to heterochromatin throughout the rRNA gene. To directly investigate the role of rRNA synthesis in pluripotency, hESCs were treated with the Pol I inhibitor, CX-5461. The direct reduction of rRNA synthesis by CX-5461 induces the expression of markers for all three germ layers, reduces the expression of pluripotency markers, and is overall similar to the ACTIVIN A induced changes. This work indicates that the dissociation of UBTF from the rRNA gene, and corresponding reduction in transcription, represent early regulatory events during the directed differentiation of pluripotent stem cells.
UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America.
Jessica L
JL
Woolnough
UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America.
Blake L
BL
Atwood
UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America.
Zhong
Z
Liu
UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America.
Rui
R
Zhao
UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America.
Keith E
KE
Giles
D028341:Activins / Q000378:metabolism; D052160:Benzothiazoles / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D020459:Genes, rRNA; D000066449:Human Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D009287:Naphthyridines / Q000494:pharmacology; D035463:Pol1 Transcription Initiation Complex Proteins / Q000378:metabolism; D012318:RNA Polymerase I / Q000037:antagonists & inhibitors; D012335:RNA, Ribosomal / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects
D052160:Benzothiazoles; C557717:CX 5461; D009287:Naphthyridines; D035463:Pol1 Transcription Initiation Complex Proteins; D012335:RNA, Ribosomal; C422405:activin A; C063844:transcription factor UBF; D028341:Activins; D012318:RNA Polymerase I