TLE2

TLE2 is a nuclear transcriptional corepressor of the Groucho/TLE family that lacks intrinsic DNA-binding activity and is recruited to target promoters through direct protein-protein interactions with sequence-specific transcription factors (PMID:9874198, PMID:9887105). It carries two separable repression domains — an N-terminal Gln-rich domain and an internal Ser/Thr/Pro-rich domain — and homo- and heterodimerizes through a short region within the N-terminal repression domain, where the Gln-rich domain can act dominant-negatively against partner-mediated repression (PMID:9874198, PMID:9887105). TLE2 engages a broad set of DNA-binding factors to mediate repression, including HES proteins (PMID:9874198), PRDI-BF1/Blimp-1 at the IFN-beta promoter (PMID:9887105), RUNX/AML factors at nuclear matrix sites where it suppresses osteocalcin transcription (PMID:10825294), and the pancreatic factors Nkx2-2, Hes1, Arx, and Nkx6-1 (PMID:18778483). Through cooperation with FoxG1 via its eh1 and YWPMSPF motifs, and as a downstream effector of Rx1, TLE2 participates in telencephalic and retinal progenitor specification (PMID:20356955, PMID:24038725). In viral latency, TLE2 binds the KSHV RTA protein and competes with RBP-Jkappa for the same Pro-rich domain, repressing RTA transactivation and lytic replication (PMID:19939918). In cancer, TLE2 acts as a suppressor of Wnt and hedgehog signaling (PMID:27414086, PMID:31578411), and its mRNA is destabilized by DDX3X in pancreatic ductal adenocarcinoma, relieving TLE2-KLF4-dependent repression of MYL9 to drive F-actin remodeling and metastasis (PMID:40938994).

1. 1998 Medium

   Established the molecular architecture of TLE2 as a corepressor — defining where its repression activity resides and how it oligomerizes — and linked it to HES factors.

   Evidence Gal4 fusion repression assays, dimerization mapping, and interaction studies in neural/non-neural tissues

   PMID:9874198

   Open questions at the time

   • Does not identify the chromatin-modifying machinery downstream of repression
   • HES interaction not mapped to specific domains
   • Single lab
2. 1999 High

   Showed TLE2 is recruited by a sequence-specific repressor (PRDI-BF1/Blimp-1) to a defined promoter, demonstrating the recruitment-to-DNA mechanism and the dominant-negative potential of the dimerization domain.

   Evidence Co-IP, Gal4 fusion repression, dominant-negative overexpression, and IFN-beta promoter reporter assays

   PMID:9887105

   Open questions at the time

   • Endogenous IFN-beta regulation not tested
   • Co-repressor effector machinery not defined
3. 1999 Medium

   Connected TLE proteins to a conserved TUP1-SSN6-like repression mechanism through interaction with UTY/X proteins.

   Evidence Yeast two-hybrid, GST pulldown, Co-IP, and repression assays in mammalian cells

   PMID:9854018

   Open questions at the time

   • Physiological promoters using this mechanism not identified
   • TLE2-specific (vs TLE1) contribution unresolved
4. 2000 Medium

   Demonstrated TLE2 localizes to the nuclear matrix and is targeted there with RUNX/AML factors, tying its subnuclear positioning to repression of a defined target gene.

   Evidence Immunofluorescence, nuclear matrix fractionation, reporter assays, yeast two-hybrid

   PMID:10825294

   Open questions at the time

   • Mechanism of nuclear matrix tethering unknown
   • Single target promoter (osteocalcin)
5. 2001 Medium

   Defined the boundary of TLE-dependent repression by showing TLE proteins are dispensable for Cbfa/Runx repression of the BSP promoter, indicating promoter-context-specific recruitment.

   Evidence Co-transfection reporter assays with promoter deletion/mutation analysis

   PMID:11283267

   Open questions at the time

   • Does not explain which features select TLE-dependent vs independent promoters
6. 2001 Medium

   Identified TLE2 (Grg2) as a transcriptional target of an oncoprotein, linking its induction to leukemic pro-B cell survival.

   Evidence Representational difference analysis, immunoblot, inducible E2A-HLF expression

   PMID:11486032

   Open questions at the time

   • Direct vs indirect transcriptional activation not resolved
   • Functional requirement of Grg2 for survival not tested by loss-of-function
7. 2008 Medium

   Extended the partner repertoire to pancreatic transcription factors and showed TLE2 modulates Arx repressive activity, placing it in islet cell-fate regulation.

   Evidence Co-IP for multiple partners and reporter assays in a beta-cell line

   PMID:18778483

   Open questions at the time

   • In vivo pancreatic requirement not tested
   • Direct vs indirect modulation of Arx unresolved
8. 2010 High

   Established TLE2 as a functional cooperating corepressor for FoxG1 in vivo, mapping the binding motifs required for telencephalon specification.

   Evidence Binding-motif mutagenesis, morpholino knockdown, ectopic neurogenesis assay, and in situ hybridization in Xenopus

   PMID:20356955

   Open questions at the time

   • Mammalian conservation of this requirement not addressed
   • Downstream repressed genes only partly defined
9. 2013 Medium

   Placed TLE2 downstream of Rx1 as an effector that represses endomesodermal genes to specify retinal progenitor identity.

   Evidence Rx1-regulated gene screen with gain/loss-of-function and reporter assays in Xenopus

   PMID:24038725

   Open questions at the time

   • Direct target promoters of TLE2 in retinal precursors not mapped
   • Partner transcription factor in this context not defined
10. 2009 High

    Revealed a virological role: TLE2 represses KSHV RTA by competing with RBP-Jkappa for the same domain, stabilizing latency.

    Evidence Yeast two-hybrid, GST pulldown, Co-IP, co-localization, reporter and virion production assays with domain mapping

    PMID:19939918

    Open questions at the time

    • Endogenous TLE2 contribution to natural latency reactivation not quantified
    • Relative affinities of TLE2 vs RBP-Jkappa not measured
11. 2016 Medium

    Positioned TLE2 as a suppressor of Wnt signaling acting downstream of NDRG1 in esophageal squamous carcinoma cells.

    Evidence Co-IP, lentiviral overexpression, RNAi, and rescue reporter/western assays

    PMID:27414086

    Open questions at the time

    • Direct vs indirect effect on beta-catenin unresolved
    • Transcriptional targets in Wnt suppression not identified
12. 2019 Medium

    Linked TLE2 to suppression of cancer stem-like properties via the hedgehog pathway in ovarian cancer.

    Evidence shRNA screen with side-population flow cytometry, sphere/clonogenicity assays, xenografts, and pathway analysis

    PMID:31578411

    Open questions at the time

    • Mechanism connecting TLE2 to hedgehog output not defined
    • Direct hedgehog-component interactions untested
13. 2025 High

    Defined a complete regulatory axis in PDAC: DDX3X destabilizes TLE2 mRNA, and TLE2-KLF4 repression of MYL9 controls cytoskeletal mechanics and metastasis.

    Evidence CRISPR-Cas9 orthotopic screen, mRNA stability assays, Co-IP, F-actin and traction force microscopy, in vivo models

    PMID:40938994

    Open questions at the time

    • Whether KLF4-MYL9 repression operates outside PDAC unknown
    • Direct binding of TLE2 to the MYL9 promoter region not detailed

• The chromatin-level effector machinery through which TLE2 enforces repression and the rules selecting its partner transcription factors across tissues remain undefined.
• No histone-modifier or chromatin remodeler defined as TLE2 effector
• Structural basis of partner discrimination unknown
• Endogenous genome-wide TLE2 occupancy not mapped