Hypoxia-inducible factor-dependent histone deacetylase activity determines stem cell fate in the placenta.
Hypoxia-inducible factor (HIF) is a heterodimeric transcription factor composed of HIFalpha and the arylhydrocarbon receptor nuclear translocator (ARNT/HIF1beta). Previously, we have reported that ARNT function is required for murine placental development. Here, we used cultured trophoblast stem (TS) cells to investigate the molecular basis of this requirement. In vitro, wild-type TS cell differentiation is largely restricted to spongiotrophoblasts and giant cells. Interestingly, Arnt-null TS cells differentiated into chorionic trophoblasts and syncytiotrophoblasts, as demonstrated by their expression of Tfeb, glial cells missing 1 (Gcm1) and the HIV receptor CXCR4. During this process, a region of the differentiating Arnt-null TS cells underwent granzyme B-mediated apoptosis, suggesting a role for this pathway in murine syncytiotrophoblast turnover. Surprisingly, HIF1alpha and HIF2alpha were induced during TS cell differentiation in 20% O2; additionally, pVHL levels were modulated during the same time period. These results suggest that oxygen-independent HIF functions are crucial to this differentiation process. As histone deacetylase (HDAC) activity has been linked to HIF-dependent gene expression, we investigated whether ARNT deficiency affects this epigenetic regulator. Interestingly, Arnt-null TS cells had reduced HDAC activity, increased global histone acetylation, and altered class II HDAC subcellular localization. In wild-type TS cells, inhibition of HDAC activity recapitulated the Arnt-null phenotype, suggesting that crosstalk between the HIFs and the HDACs is required for normal trophoblast differentiation. Thus, the HIFs play important roles in modulating the developmental plasticity of stem cells by integrating physiological, transcriptional and epigenetic inputs.
Department of Pediatrics and Molecular Medicine Program, University of California, Parnassus Avenue, San Francisco, CA 94143, USA.
Emin
E
Maltepe
Geoffrey W
GW
Krampitz
Kelly M
KM
Okazaki
Kristy
K
Red-Horse
Winifred
W
Mak
M Celeste
MC
Simon
Susan J
SJ
Fisher
D000818:Animals; D017209:Apoptosis; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D002454:Cell Differentiation; D002823:Chorion / Q000166:cytology / Q000502:physiology; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006655:Histone Deacetylases / Q000378:metabolism*; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D010920:Placenta / Q000166:cytology*; D011247:Pregnancy; D018336:Receptors, Aryl Hydrocarbon / Q000172:deficiency / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014327:Trophoblasts / Q000166:cytology
C497397:Arnt protein, mouse; D004268:DNA-Binding Proteins; C497443:Hif1a protein, mouse; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D006655:Histone Deacetylases