Plet1 is an epigenetically regulated cell surface protein that provides essential cues to direct trophoblast stem cell differentiation.
Gene loci that are hypermethylated and repressed in embryonic (ESCs) but hypomethylated and expressed in trophoblast (TSCs) stem cells are very rare and may have particularly important roles in early developmental cell fate decisions, as previously shown for Elf5. Here, we assessed another member of this small group of genes, Placenta Expressed Transcript 1 (Plet1), for its function in establishing trophoblast lineage identity and modulating trophoblast differentiation. We find that Plet1 is tightly repressed by DNA methylation in ESCs but expressed on the cell surface of TSCs and trophoblast giant cells. In hypomethylated ESCs that are prone to acquire some trophoblast characteristics, Plet1 is required to confer a trophoblast-specific gene expression pattern, including up-regulation of Elf5. Plet1 displays an unusual biphasic expression profile during TSC differentiation and thus may be pivotal in balancing trophoblast self-renewal and differentiation. Furthermore, overexpression and CRISPR/Cas9-mediated knockout in TSCs showed that high Plet1 levels favour differentiation towards the trophoblast giant cell lineage, whereas lack of Plet1 preferentially induces syncytiotrophoblast formation. Thus, the endogenous dynamics of Plet1 expression establish important patterning cues within the trophoblast compartment by promoting differentiation towards the syncytiotrophoblast or giant cell pathway in Plet1-low and Plet1-high cells, respectively.
Epigenetics Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.|Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
Alexander
A
Murray
Epigenetics Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
Arnold R
AR
Sienerth
Epigenetics Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.|Centre for Trophoblast Research, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
Myriam
M
Hemberger
D000818:Animals; D002454:Cell Differentiation; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D044127:Epigenesis, Genetic; D018507:Gene Expression Regulation, Developmental; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D011257:Pregnancy Proteins / Q000235:genetics* / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism* / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism* / Q000502:physiology
D004268:DNA-Binding Proteins; C500759:Elf5 protein, mouse; D008565:Membrane Proteins; C526396:PLET1 protein, human; D011257:Pregnancy Proteins; D014157:Transcription Factors