MAPRE2

MAPRE2 (EB2) is a microtubule plus-end tracking protein that controls microtubule dynamics across mitosis, epithelial differentiation, cell migration, and membrane protein trafficking (PMID:27030108, PMID:23813963, PMID:26527684). During mitotic entry and progression, Aurora B and CDK1 phosphorylate MAPRE2 at the amino terminus and the linker between its calponin-homology and end-binding domains, reducing its microtubule binding affinity; blocking this phosphorylation stabilizes kinetochore microtubule dynamics, delays metaphase plate formation, and produces aneuploidy (PMID:27030108). Consistent with a conserved role in spindle function, MAPRE2 decorates the meiotic spindle and is required for kinetochore-microtubule attachment, chromosome alignment, and progression past the spindle assembly checkpoint in oocytes (PMID:35398309), and it associates with the mitotic spindle in neural progenitors where a truncating mutation stalls prometaphase and triggers p53-dependent apoptosis (PMID:41725360). In differentiating epithelia, MAPRE2 drives initial microtubule reorganization by limiting EB1/ACF7 lattice association and formin-dependent actin co-alignment (PMID:23813963). It promotes focal adhesion turnover and cell motility through a complex with HAX1 (PMID:26527684) and facilitates anterograde trafficking of the TRPM4 channel to the plasma membrane via an EB-binding motif on the channel (PMID:31112396). In cardiomyocytes, MAPRE2 sustains voltage-gated sodium channel function and adherens junction integrity through a tubulin-detyrosination pathway, established by epistasis with the tubulin tyrosine ligase ttl (PMID:38095085). MAPRE2 protein levels are set by ubiquitin-mediated degradation through the E3 ligases WDHD1 and ASB14 (PMID:32426268, PMID:38319584). Gain-of-function mutations that increase MAPRE2 microtubule binding and plus-end dwell time perturb cranial neural crest migration and craniofacial development, causing circumferential skin creases Kunze type (CSC-KT) syndrome (PMID:26637975, PMID:33654163).

1. 2013 High

   Established that MAPRE2 actively shapes microtubule architecture during a developmental program rather than simply tracking plus ends, by showing it is required for the initial microtubule reorganization of epithelial differentiation.

   Evidence siRNA knockdown with live-cell imaging, formin-inhibitor rescue, and in situ tissue validation in epithelial cells

   PMID:23813963

   Open questions at the time

   • Molecular basis for how EB2 restrains EB1/ACF7 lattice association not resolved
   • Direct binding partners mediating the actin co-alignment not identified
2. 2015 High

   Linked MAPRE2 to a human Mendelian disease and defined the disease allele as gain-of-function, showing CSC-KT mutations enhance microtubule binding and disrupt craniofacial patterning.

   Evidence Microtubule co-sedimentation assays with patient mutants and zebrafish branchial arch analysis

   PMID:26637975

   Open questions at the time

   • Cellular pathway connecting increased plus-end dwell time to craniofacial defects not yet defined
   • Effect on downstream effectors not measured
3. 2015 High

   Identified a direct effector mechanism for MAPRE2 in cell migration by showing an EB2-HAX1 complex drives focal adhesion turnover.

   Evidence Quantitative proteomics with Co-IP validation, siRNA loss-of-function, in vitro migration and in vivo wound-healing assays

   PMID:26527684

   Open questions at the time

   • Structural basis of the EB2-HAX1 interaction not determined
   • How the complex acts on focal adhesions mechanistically not resolved
4. 2016 High

   Defined the regulatory logic of MAPRE2 in mitosis, showing Aurora B/CDK1 phosphorylation tunes its microtubule affinity to permit normal kinetochore microtubule dynamics and faithful chromosome segregation.

   Evidence In vitro kinase assays, non-phosphorylatable mutants, live-cell imaging and kinetochore microtubule dynamics assays

   PMID:27030108

   Open questions at the time

   • Relative contributions of individual phospho-sites not dissected
   • Phosphatase that reverses these modifications not identified
5. 2019 Medium

   Extended MAPRE2 function to membrane protein delivery by showing it is required for TRPM4 anterograde trafficking through an EB-binding motif.

   Evidence Co-IP with motif mutagenesis, immunofluorescence, cell invasion and focal adhesion assays

   PMID:31112396

   Open questions at the time

   • EB1 and EB2 specific contributions not fully separated
   • Whether trafficking effect is direct or via microtubule dynamics unclear
6. 2020 Medium

   Began to define how MAPRE2 abundance is controlled, identifying WDHD1 as an E3 ligase that ubiquitinates and degrades nuclear MAPRE2.

   Evidence Co-IP, ubiquitination and protein-stability assays, knockout/knockdown in cells and animals

   PMID:32426268

   Open questions at the time

   • Single lab; reciprocal validation limited
   • Functional consequence of nuclear MAPRE2 pool not defined
7. 2021 Medium

   Connected the CSC-KT gain-of-function allele to a cellular disease mechanism by showing mutant MAPRE2 alters neural crest focal adhesion dynamics and migration.

   Evidence Patient iPSC lines with isogenic CRISPR controls, neural crest differentiation, migration assays, chick xenotransplantation

   PMID:33654163

   Open questions at the time

   • Link between altered plus-end dwell time and focal adhesion changes not mechanistically resolved
   • Single lab
8. 2022 Medium

   Showed MAPRE2 spindle function is conserved in meiosis, being required for kinetochore-microtubule attachment and checkpoint satisfaction in oocytes.

   Evidence siRNA knockdown with spindle assembly checkpoint markers, cyclin B1 western blot and polar body extrusion assays in mouse oocytes

   PMID:35398309

   Open questions at the time

   • Whether meiotic role is regulated by the same Aurora B/CDK1 phosphorylation not tested
   • Single lab
9. 2023 High

   Defined a tissue-specific mechanism in heart, establishing by epistasis that MAPRE2 supports sodium channel function and adherens junctions through tubulin detyrosination.

   Evidence CRISPR zebrafish knockout and iPSC-CM knockdown with patch clamping, voltage mapping, plus-end tracking, and ttl-knockdown genetic rescue

   PMID:38095085

   Open questions at the time

   • Direct link between MAPRE2 and the detyrosination enzymes not established
   • How detyrosinated tubulin regulates the channel not resolved
10. 2024 Medium

    Added a second E3 ligase, ASB14, controlling MAPRE2 turnover, with degradation gating cardiomyocyte proliferation and cardiac repair.

    Evidence Microarray, ASB14 silencing in vitro and in vivo, western blot for MAPRE2, cardiomyocyte proliferation assays

    PMID:38319584

    Open questions at the time

    • Mechanistic detail of ubiquitination limited
    • Relationship between ASB14- and WDHD1-mediated degradation not clarified
11. 2024 Medium

    Positioned MAPRE2 as a phosphorylation substrate of CDKL5 in neurons, linking its modification to CDKL5 phase separation and disease variants.

    Evidence Optogenetic LLPS induction, super-resolution imaging, phosphorylation assays with CDKL5 truncation mutants, and patient CDD neurons (preprint)

    PMID:bio_10.1101_2024.11.11.622878 PMID:bio_10.1101_2024.11.18.624084

    Open questions at the time

    • Functional consequence of CDKL5-mediated EB2 phosphorylation not defined
    • Preprint, not peer reviewed; single lab
12. 2026 High

    Demonstrated that a disease truncation disrupts MAPRE2 spindle function in neural progenitors, stalling mitosis and triggering p53-dependent apoptosis as a likely basis for neurodevelopmental phenotypes.

    Evidence Transgenic mouse models and human stem cell-derived neural progenitors with time-lapse imaging and p53 pathway analysis

    PMID:41725360

    Open questions at the time

    • Whether truncation acts as loss- or gain-of-function on the spindle not fully resolved
    • Link to focal-adhesion phenotypes of other mutants not established

• How MAPRE2's distinct cellular roles—spindle dynamics, focal adhesion turnover, membrane trafficking, and detyrosination signaling—are coordinated and differentially regulated across tissues remains unresolved.
• No unifying model linking phospho-regulation to tissue-specific outputs
• Structural basis of mutant gain-of-function plus-end dwell time not determined
• Direct enzymatic link to tubulin detyrosination not established