DENND10

DENND10 (FAM45A) is an endosomal DENN-domain protein that governs endolysosomal trafficking and extracellular vesicle biogenesis (PMID:30771381, PMID:38987765). It localizes to late/multivesicular endosomes, where its loss causes perinuclear endosome clustering and a delay in the early-to-late endosome transition that impairs EGF receptor endocytosis and attenuates secretion of selected exosome subpopulations (PMID:30771381). DENND10 acts upstream of Rab27a/b, with which it forms a nucleotide-dependent complex, positioning these Rab GTPases as downstream effectors in endosome motility and exosome biogenesis (PMID:30771381). Structurally, DENND10 is an integral subunit of the 16-subunit Commander complex, where cryo-EM places it within an effector module alongside the Retriever subcomplex (VPS26C, VPS29, VPS35L), scaffolded onto the COMMD1-10 core by CCDC22 and CCDC93 (PMID:38459129). Through this trafficking machinery DENND10 controls cell-physiological outputs: its knockout in breast cancer cells disrupts EV biogenesis and remodels the ECM/adhesion content of secreted EVs, reducing cell spreading, migration, invasion, and metastasis—defects rescued by wild-type conditioned medium or EVs (PMID:38987765)—and in neurons it supports neurite extension via downstream Rab27 and the CCC subunit CCDC22 (PMID:40330880).

1. 2019 Medium

   Establishing where DENND10 acts and what it does, defining it as a late/multivesicular endosome protein required for endosome maturation and exosome secretion.

   Evidence siRNA/shRNA knockdown with colocalization microscopy and endocytosis assays

   PMID:30771381

   Open questions at the time

   • Molecular activity of the DENN domain not biochemically defined
   • Mechanism linking endosome maturation delay to exosome defect not resolved
2. 2019 Medium

   Connecting DENND10 to a downstream effector by showing it forms a nucleotide-dependent complex with Rab27a/b, placing these GTPases below DENND10 in endosome motility and exosome pathways.

   Evidence Co-immunoprecipitation, colocalization, and nucleotide-loading experiments

   PMID:30771381

   Open questions at the time

   • Whether DENND10 acts as a GEF toward Rab27 not demonstrated
   • Direct vs indirect nature of the complex not established
3. 2024 High

   Resolving DENND10's molecular context by placing it structurally within the Commander complex as part of a Retriever-containing effector module scaffolded by CCDC22/CCDC93.

   Evidence Cryo-EM of endogenous human Commander complex with MS-based proteomics

   PMID:38459129

   Open questions at the time

   • Functional contribution of DENND10 within the assembled complex not tested
   • How Commander assembly relates to the Rab27 pathway unresolved
4. 2024 Medium

   Linking DENND10-dependent trafficking to disease-relevant cell behavior, showing its loss impairs EV biogenesis and reduces migration, invasion, and metastasis through altered EV cargo.

   Evidence CRISPR knockout in breast cancer cells, in vitro/in vivo motility and metastasis assays, EV/conditioned-medium rescue, global proteomics

   PMID:38987765

   Open questions at the time

   • Specific EV cargo responsible for migratory rescue not pinpointed
   • Single-lab, single cancer model
5. 2025 Medium

   Generalizing DENND10's trafficking role to neuronal morphogenesis and placing it genetically upstream of both Rab27 and the CCC subunit CCDC22.

   Evidence Loss-of-function in neuronal cultures and primary cortical neurons, quantitative proteomics, epistasis with Rab27 and CCDC22

   PMID:40330880

   Open questions at the time

   • Cargo whose trafficking drives neurite extension not identified
   • In vivo neuronal relevance not tested

• The biochemical activity of the DENND10 DENN domain and whether it functions as a guanine nucleotide exchange factor for Rab27 remain undefined.
• No reconstituted GEF or enzymatic assay
• No structural model of the DENN domain engaging a Rab
• Relationship between Commander membership and Rab27 regulation unresolved