EOLA1

EOLA1 is an endothelial protein that functions as a negative regulator of LPS-induced inflammatory signaling and apoptosis while promoting endothelial cell proliferation (PMID:24916366, PMID:15541360, PMID:16215939). It physically interacts with metallothionein 2A (MT2A), and this association is central to its anti-inflammatory output: loss of EOLA1 enhances LPS-induced IL-6 production and apoptosis in HUVECs, with MT2A acting downstream as a key effector of IL-6 expression (PMID:15541360, PMID:16215939, PMID:24916366). EOLA1 likewise restrains LPS-induced VCAM-1 expression through its MT2A partnership, with knockdown raising and overexpression lowering VCAM-1 (PMID:26881174). EOLA1 localizes to both nucleus and cytoplasm, consistent with a signal-transduction role (PMID:21223654). Structurally, EOLA1 adopts an ASC-1 homology (ASCH) β-barrel fold with a conserved 'GxKxxExR' cavity implying nucleotide binding and a positively charged cleft resembling that of RNA-binding ASCH and YTH domain proteins (PMID:31569543); comparative crystallography of the mouse ortholog places it in the ASCH family but with substrate selectivity distinct from the ac4C amidohydrolase EcYqfB and human TRIP4-ASCH (PMID:40939588). A catalytic or RNA-binding activity intrinsic to EOLA1 has not been directly demonstrated in the available corpus.

1. 2004 Medium

   Established the first molecular partner of EOLA1 and its first cellular phenotype, framing it as an endothelial protein that interacts with MT2A and drives proliferation.

   Evidence Yeast two-hybrid screen of a human liver cDNA library with reciprocal co-IP confirmation; stable transfection proliferation assay in ECV304 cells

   PMID:15541360 PMID:16215939

   Open questions at the time

   • Interaction mapped only by Y2H/co-IP, no interface or domain mapping
   • Functional consequence of the MT2A interaction not yet defined
   • Proliferation effect tied to a single cell line
2. 2005 Low

   Tested whether elevated EOLA1 protein is sufficient to drive proliferation, reinforcing a pro-proliferative role.

   Evidence Inducible overexpression (pOPRSVI-EOLA1) and growth-curve counting in ECV304 cells

   PMID:16185414

   Open questions at the time

   • Single overexpression method without mechanistic pathway placement
   • No molecular readout linking EOLA1 to a proliferation pathway
3. 2007 Low

   Addressed whether EOLA1 is required for proliferation, complementing the gain-of-function data with loss-of-function evidence.

   Evidence siRNA knockdown plus proliferation counting in ECV304 cells

   PMID:17557240

   Open questions at the time

   • Phenotype only, no mechanism
   • Single RNAi method, no rescue control
4. 2010 Medium

   Determined where EOLA1 acts in the cell, supporting a dual nuclear/cytoplasmic signal-transduction role.

   Evidence EGFP-EOLA1 fusion imaged by laser scanning confocal and immunoelectron microscopy in ECV304 cells

   PMID:21223654

   Open questions at the time

   • Localization shown via overexpressed fusion, not endogenous protein
   • Functional significance of nuclear vs cytoplasmic pools not dissected
5. 2014 Medium

   Placed EOLA1 in an inflammatory signaling pathway, showing it acts upstream of MT2A to restrain LPS-induced IL-6 and apoptosis.

   Evidence siRNA knockdown of EOLA1 and MT2A, LPS stimulation, IL-6 and apoptosis readouts in HUVECs

   PMID:24916366

   Open questions at the time

   • Molecular mechanism by which EOLA1 regulates MT2A unresolved
   • Single lab and cell system
   • How LPS induces EOLA1 expression not defined
6. 2015 Medium

   Extended EOLA1's anti-inflammatory role to adhesion molecule control, showing MT2A-dependent suppression of LPS-induced VCAM-1.

   Evidence Reciprocal siRNA knockdown and overexpression of EOLA1, MT2A knockdown, VCAM-1 quantification after LPS in ECV304 cells

   PMID:26881174

   Open questions at the time

   • Direct biochemical link between EOLA1-MT2A binding and VCAM-1 transcription not established
   • Diffuse localization not correlated with signaling state
7. 2019 High

   Provided the first structural framework, assigning EOLA1 to the ASCH β-barrel fold with cavity features implying nucleotide and RNA binding.

   Evidence 1.71 Å X-ray crystal structure of human EOLA1 with structural comparison to YTH and ASCH proteins

   PMID:31569543

   Open questions at the time

   • No experimental demonstration of nucleotide or RNA binding
   • No ligand-bound structure
   • Structural inference not linked to the MT2A/inflammatory function
8. 2025 Medium

   Compared EOLA1 against catalytically active ASCH proteins, refining family placement and indicating distinct substrate selectivity.

   Evidence X-ray crystallography of mouse EOLA1 with comparative analysis against EcYqfB and TRIP4-ASCH

   PMID:40939588

   Open questions at the time

   • EOLA1's own catalytic activity not directly measured
   • Activity data shown only for EcYqfB, not EOLA1
   • No identified physiological substrate

• Whether EOLA1 possesses intrinsic catalytic or RNA-binding activity and how this connects to its MT2A-dependent anti-inflammatory function remains unresolved.
• No demonstrated enzymatic or RNA-binding activity for EOLA1 itself
• Mechanistic bridge between the structural fold and the inflammatory phenotype absent
• No in vivo or disease-level validation