ROGDI

ROGDI is a regulator of V-ATPase-dependent organelle acidification that operates as a novel subunit of the mammalian Rabconnectin-3 complex, the functional equivalent of the yeast RAVE complex (PMID:40049412). Acting as the structural and functional homolog of yeast Rav2, ROGDI can replace Rav2 in yeast and bridges the N-terminal domains of both Rabconnectin-3α and Rabconnectin-3β, co-immunoprecipitating with these subunits and co-localizing with Rabconnectin-3α in acidic perinuclear lysosomes (PMID:40049412). Structurally, ROGDI is an elongated curved protein whose α domain forms a leucine-zipper-like four-helix bundle (N-terminal H1 paired antiparallel with C-terminal H6) that provides a platform for these protein–protein interactions; KTS-associated mutations disrupt this bundle and destabilize the protein (PMID:28638151). ROGDI is required in vivo for V-ATPase-dependent tooth acidification, as Rogdi knockout mice lack cyclic dental acidification during enamel maturation and show altered expression of V-ATPase-associated factors and enamel matrix proteins (PMID:38172607). In neurons, ROGDI localizes to presynaptic sites alongside scaffolding and synaptic vesicle proteins and harbors intrinsic presynaptic targeting signals (PMID:29150638), and in Drosophila it promotes sleep by supporting GABAergic transmission upstream of wake-promoting dopaminergic pathways (PMID:28900300). Biallelic loss-of-function mutations in ROGDI cause Kohlschütter-Tönz syndrome, with a nonsense mutation (p.Arg157*) abolishing detectable protein (PMID:22482807). A distinct role in cell cycle progression and the DNA damage response has been reported in cervical cancer cells, where ROGDI depletion reduces CDK/cyclin expression and arrests cells at G2/M (PMID:27636029).

1. 2012 Medium

   Established that ROGDI loss is the molecular cause of a recessive disease, linking the gene to a defined human phenotype before its biochemical function was known.

   Evidence Immunofluorescence/immunodetection in cells of KTS-affected individuals homozygous for p.Arg157*

   PMID:22482807

   Open questions at the time

   • Nuclear envelope localization not reconciled with later lysosomal/presynaptic findings
   • No molecular function assigned
   • Single method in patient cells
2. 2016 Medium

   Tested whether ROGDI influences proliferation, revealing a role in cell cycle progression and the DNA damage response distinct from its later-defined acidification function.

   Evidence siRNA knockdown in cervical cancer cells with flow cytometry, clonogenic assay, and Western blot for CDKs/cyclins and γ-H2AX

   PMID:27636029

   Open questions at the time

   • Mechanism connecting ROGDI to CDK/cyclin expression unknown
   • Single cell-line context
   • Relationship to V-ATPase role unexplained
3. 2017 High

   Determined the atomic structure of ROGDI, defining a leucine-zipper-like four-helix bundle as a protein-interaction platform and showing how disease mutations destabilize it.

   Evidence X-ray crystallography with biochemical stability assays and mutagenesis of KTS-associated variants

   PMID:28638151

   Open questions at the time

   • Interaction partners bound by the platform not identified in this study
   • No structure of a ROGDI-containing complex
4. 2017 Medium

   Located ROGDI to presynaptic terminals and demonstrated intrinsic targeting, framing a neuronal role consistent with the seizure phenotype of KTS.

   Evidence Immunofluorescence of endogenous Rogdi and live imaging of GFP-Rogdi in rat hippocampal neurons

   PMID:29150638

   Open questions at the time

   • Presynaptic molecular function undefined
   • Targeting signal sequence not mapped
   • No interacting presynaptic partner shown biochemically
5. 2017 Medium

   Placed Rogdi in a defined neural circuit by showing it promotes sleep through GABAergic transmission upstream of dopaminergic wake pathways.

   Evidence Drosophila loss-of-function, cell-type-specific transgenic rescue, pharmacological GABA manipulation, and sleep behavioral assays

   PMID:28900300

   Open questions at the time

   • Molecular link between Rogdi and GABAergic signaling not established
   • Mammalian relevance of sleep phenotype untested
6. 2024 Medium

   Connected ROGDI to V-ATPase-dependent acidification in vivo, explaining the dental phenotype of KTS through failed enamel acidification.

   Evidence Rogdi knockout mouse with SEM, RNA-seq of postnatal incisors, and seizure testing

   PMID:38172607

   Open questions at the time

   • Direct V-ATPase interaction not demonstrated in this study
   • Transcriptomic changes are correlative
   • Tissue-specificity of acidification defect unexplored
7. 2025 High

   Defined the biochemical function of ROGDI as the Rav2 homolog and a bridging subunit of the Rabconnectin-3/RAVE complex regulating V-ATPase reassembly and lysosomal acidification.

   Evidence Yeast functional complementation, Co-IP from mammalian lysates, lysosome immunopurification, immunofluorescence, and molecular modeling

   PMID:40049412

   Open questions at the time

   • No experimental structure of the assembled ROGDI–Rabconnectin-3 complex
   • Bridging model is from modeling, not direct structure
   • Mechanism of V-ATPase reassembly regulation not kinetically characterized
8. 2024 Low

   Provided ortholog-based support that the RAVE/Rabconnectin-3 module sustains V-ATPase assembly and vacuolar pH during aging.

   Evidence Yeast replicative aging assays, vacuolar pH measurement, V-ATPase fractionation, and Rav1/Rav2 genetic manipulation (preprint)

   Open questions at the time

   • Yeast ortholog study, not direct ROGDI evidence
   • Preprint, not peer-reviewed
   • Aging relevance of mammalian ROGDI untested

• How ROGDI's lysosomal V-ATPase function mechanistically connects to its reported presynaptic, GABAergic, and cell-cycle roles remains unresolved.
• Unified mechanism across tissues lacking
• Whether neuronal and cell-cycle phenotypes are downstream of acidification defects untested
• No structure of ROGDI bound to Rabconnectin-3 subunits