Entry created on 1 July 2019 (Revision 1.0) Annotator: Rita Pancsa
Basic protein information
Accession P03372
Common name ERα
Gene ESR1
Organism Homo sapiens
Uniprot name Estrogen receptor
Basic LLPS information
Organelle enhanceosome; nuclear body; robustly E2-activated enhancers (MegaTrans) enhancers
Type of experimental evidence
Protein region(s) mediating LLPS
79
-
174
H/S/P/G-rich IDR
Based on the experimental results of the following publication: 30833784
Molecular features viewer
PDB structures
View on PDBe
Extended LLPS information
Functional description
A crucial feature of differentiated cells is the rapid activation of enhancer-driven transcriptional programs in response to signals. Estrogen signaling activates 7,000–8,000 enhancers genome-wide, out of which 1,248 are exceptionally active, on the basis of eRNA transcription and regulatory potential. These exceptionally active enhancers are characterized by E2-dependent recruitment of high levels of ERα, RNA Pol-II, MegaTrans components (for example, GATA3, FOXA1 and AP2γ), MED1 and P300 and by higher induced chromatin openness when compared to weak ERα-bound enhancers. These robustly E2-activated enhancers are referred to as MegaTrans enhancers. The initial, signal-dependent nucleation of enhanceosome complexes on potent, acutely activated enhancers, but not on basally active enhancers, represents an assembly process that is sensitive to 1,6-HD and is thus probably driven by phase separation. Chronic stimulation with E2 causes a fluid to hydrogel-like transition at enhancers and prevents ligand-induced enhancer proximity. Acutely active e2-responsive MegaTrans enhancers concentrate a protein complex that can undergo phase transition. GATA3 and ERα, two key components recruited to the MegaTrans enhancers, are capable of phase separating in vitro and in vivo, forming functional condensates with distinct fluid dynamics at MegaTrans enhancer loci (PMID:30833784).
Literature supporting the LLPS: 30833784
Functional class of membraneless organelle: activation/nucleation/signal amplification/bioreactor
Binding partners (at biological protein concentrations)
1) TFF1e eRNA (not required but promotes LLPS)
Type of RNA(s) required/used for the LLPS at biological protein concentrations
other specific RNA: TFF1e eRNA
Molecular interaction types contributing to LLPS
Not known
Determinants of phase separation and droplet properties
1) crowding agent concentration
Membrane cluster No
Partner-dependent No
RNA-dependent No
PTM required No
Domain-motif interactions No
Discrete oligomerization No
Regulation and disease
Post-translational modifications affecting LLPS
Position Residue PTM Effect Reference Modifying enzyme Notes
Isoforms known to affect LLPS
Isoform Effect Reference
All known isoforms containing sequence changes in the LLPS region(s)
Position type Isoform names from UniProt
Disease mutations affecting LLPS
Mutation dbSNP Disease OMIM Effect Reference Notes
Experimental information
Experimental techniques applied to prove/investigate LLPS
Condensates of purified ERα fused to MBP (with 5% PEG) exhibited typical characteristics of phase-separated liquid droplets (morphology), while MBP alone did not. Additionally, when GATA3-MBP and ERα-MBP (fusion protein) were mixed together in vitro, two-color confocal microscopy analysis revealed that they are enriched and coexist in a single, phase-separated condensate (protein co-localization). The IDR of ERα fused to mCherry-Cry2 (fusion protein) demonstrated efficient clustering and droplet formation on blue light stimulation and exhibited liquid droplet fusion behavior (morphology) in transgenic HEK293 cells in vivo. Live-cell microscopy imaging revealed acute assembly of nuclear (fluorescently labeled) ERα foci within 1 min after E2 treatment in ~80% of the cells, with an average of 121 ± 25 distinct foci per nucleus (particle size and count), whereas no ERα foci were observed before E2 treatment. RNA fluorescence in situ hybridization (FISH) experiments showed that at least a subset of ERα foci develops in proximity to MegaTrans enhancers (protein co-localization). When in vitro transcribed, fluorescently labeled TFF1e eRNA was mixed with purified ERα-MBP or GATA3-MBP fusion proteins, in the presence of 5% PEG and 200 mM NaCl, it shortened the recovery time (t1/2) of GATA3-MBP and ERα-MBP fusion protein droplets by roughly 50% (change in RNA concentration). Also, depletion of TFF1e eRNA abolished recruitment of MegaTrans components GATA3, RARα and AP2γ to TFF1 enhancer region (localization) in response to E2, with no impact on the primary transcription factor, ERα. This supports a role for eRNAs in recruiting MegaTrans components. (PMID:30833784).
Experimental observations supporting the liquid material state of the condensate
dynamic movement/reorganization of molecules within the droplet (PMID:30833784) morphological traits (PMID:30833784) sensitivity to 1,6-hexanediol (PMID:30833784)