DENND6A

DENND6A (FAM116A) is a DENN-domain guanine nucleotide exchange factor that controls discrete steps of membrane traffic governing cell migration and lysosome positioning (PMID:22595670, PMID:38296963). In the endocytic recycling pathway it acts as a GEF for Rab14 on an intermediate recycling compartment located after Rab5/Rab4 and before Rab11; loss of DENND6A traps ADAM10 in a transferrin-positive endosomal compartment, lowers surface ADAM10, and impairs N-cadherin shedding, thereby preventing resolution of cell-cell junctions during migration (PMID:22595670). On lysosomes, DENND6A serves as an effector of Arl8b that is recruited to peripheral lysosomes, where it functions as a GEF for Rab34 to assemble a RILP/dynein complex driving retrograde, dynein-dependent juxtanuclear repositioning and supporting autophagic flux under nutrient control (PMID:38296963). An in vitro reassessment additionally identifies DENND6A as a DENN-domain Arf-GAP acting on ARL8B, offering an alternative biochemical account of its lysosome-positioning role (PMID:41542567).

1. 2012 High

   Established DENND6A's first molecular activity by showing it is a Rab14 GEF acting at a defined station of the endocytic recycling pathway, linking it to surface delivery of the sheddase ADAM10 and to junction remodeling during migration.

   Evidence Functional GEF screen with siRNA knockdown, transferrin recycling and co-localization assays, ADAM10 surface measurement, N-cadherin shedding and migration assays

   PMID:22595670

   Open questions at the time

   • Direct structural basis of Rab14 recognition not resolved
   • Mechanism recruiting DENND6A to the intermediate recycling compartment not defined
   • Whether ADAM10 is the only relevant cargo unknown
2. 2024 High

   Extended DENND6A function to lysosomes by showing it acts as a Rab34 GEF downstream of Arl8b to recruit RILP/dynein for retrograde transport, placing it in a defined nutrient-responsive lysosome-positioning and autophagy pathway.

   Evidence Cell-based Rab GEF screen, Co-IP, knockdown/knockout lysosome positioning and autophagic flux assays, live imaging, epistasis with Arl8b mutants

   PMID:38296963

   Open questions at the time

   • Structural detail of the Arl8b-DENND6A effector interaction not resolved
   • How DENND6A toggles between Rab14 (recycling) and Rab34 (lysosomal) roles unknown
   • Direct vs indirect assembly of the RILP/dynein complex not fully dissected
3. 2024 Low

   Identified RAB25 as a DENND6A interactor relevant to migration, expanding the candidate partner set beyond Rab14.

   Evidence APEX2 proximity labeling with physical interaction validation and migration assays (preprint)

   PMID:bio_10.1101_2024.11.05.621850

   Open questions at the time

   • Proximity labeling is not direct binding evidence and lacks reciprocal validation
   • Functional consequence of the RAB25 interaction on DENND6A activity undefined
   • Single preprint, not peer-reviewed
4. 2026 Medium

   Challenged the GEF-only model by demonstrating in vitro Arf-GAP activity of DENND6A toward ARL8B, proposing a GAP-based explanation for lysosome positioning.

   Evidence Computational interaction screen, in vitro Arf-GAP activity assay, cell migration experiments (preprint)

   PMID:41542567

   Open questions at the time

   • Single preprint lab, not yet peer-reviewed and contradicts prior GEF model
   • GAP activity shown in vitro; cellular relevance versus Rab34 GEF role not reconciled
   • No structural basis for ARL8B GAP catalysis

• How DENND6A reconciles GEF activity toward Rab14/Rab34 with proposed GAP activity toward ARL8B, and how it is partitioned between recycling endosomes and lysosomes, remains unresolved.
• No unified biochemical model integrating GEF and GAP activities
• No structure of DENND6A bound to any partner
• Determinants of compartment-specific targeting unknown