RINT1

RINT1 is a multifunctional scaffold protein that coordinates retrograde Golgi-to-ER vesicle trafficking, genome integrity, and organelle homeostasis. It bridges ZW10 to the ER-localized SNARE syntaxin 18 to mediate retrograde transport, and independently engages the COG complex to regulate SNARE assembly at the trans-Golgi network; loss of RINT1 disperses the Golgi, triggers ER stress and unfolded protein response activation, and blocks autophagic flux (PMID:16571679, PMID:23885118, PMID:26383973, PMID:40940405). RINT1 also participates in DNA damage responses by interacting with RAD50 in a cell-cycle-dependent manner during S/G2, promoting MRN complex assembly and homologous recombination repair—functions modulated by BRIP1-mediated acetylation at K728—and suppresses telomerase-independent telomere lengthening through a p130–Rad50 complex (PMID:11096100, PMID:16600870, PMID:41740833). Bi-allelic loss-of-function RINT1 variants cause defective lipid-droplet biogenesis, aberrant phospholipid metabolism, mitochondrial dysfunction, and a multisystem disease in humans, while homozygous deletion in mice is embryonic lethal and heterozygosity promotes spontaneous tumorigenesis (PMID:37463447, PMID:31204009, PMID:17470549).

1. 2000 High

   Identifying RINT1 as a Rad50-interacting protein that functions specifically during late S/G2 established its role in the radiation-induced G2/M checkpoint, linking it to the DNA damage response.

   Evidence Yeast two-hybrid screen with domain mapping, co-immunoprecipitation across cell cycle phases, dominant-negative checkpoint assay in human cells

   PMID:11096100

   Open questions at the time

   • Mechanism by which RINT1–Rad50 interaction enforces checkpoint arrest was not defined
   • Whether RINT1 participates in DNA repair per se was unknown
   • Endogenous stoichiometry and regulation of the interaction were not characterized
2. 2006 High

   Discovery that RINT1 bridges ZW10 to the ER SNARE syntaxin 18 and is required for Golgi-to-ER retrograde transport revealed a second, membrane-trafficking function entirely distinct from its checkpoint role, and a parallel finding that RINT1 forms a p130–Rad50 complex controlling telomere length broadened its genome-maintenance portfolio.

   Evidence siRNA knockdown with ER-to-Golgi transport and Golgi morphology readouts; co-immunoprecipitation mapping ZW10-binding domain [PMID:16571679]; telomere length assays after RINT1 depletion with p130 and Rad50 co-IP [PMID:16600870]

   PMID:16571679 PMID:16600870

   Open questions at the time

   • Whether trafficking and genome-stability functions are coordinated or independent was unclear
   • Structural basis for the ZW10–RINT1–syntaxin 18 interaction was not resolved
   • How p130–RINT1–Rad50 suppresses recombination-based telomere elongation mechanistically was not established
3. 2007 High

   Localization studies and mouse genetics showed that RINT1 resides at the Golgi, ER, and centrosome, and its loss causes centrosome amplification, mitotic Golgi defects, and embryonic lethality, while Rab6 epistasis positioned RINT1 downstream of Rab6 in Golgi trafficking.

   Evidence Immunofluorescence localization, Rint1 knockout/heterozygous mouse model, siRNA epistasis with Rab6 and COG complex depletion

   PMID:17470549 PMID:17699596

   Open questions at the time

   • How RINT1 maintains centrosome integrity was mechanistically undefined
   • Whether haploinsufficient tumorigenesis reflects trafficking, genome stability, or both was unknown
   • Direct Rab6–RINT1 interaction was not demonstrated
4. 2013 High

   Identification of a ZW10-independent RINT1–COG complex interaction that regulates SNARE assembly at the trans-Golgi network established a second trafficking axis for RINT1, this time in endosome-to-TGN transport.

   Evidence Reciprocal co-immunoprecipitation, SNARE complex assembly assay, endosome-to-TGN trafficking assay after RINT1 depletion

   PMID:23885118

   Open questions at the time

   • How RINT1 partitions between ZW10 and COG complexes was not determined
   • Whether the COG-dependent pathway contributes to the Golgi fragmentation phenotype was untested
5. 2015 High

   Conditional neuronal knockout demonstrated that RINT1 loss causes chromosome fusions, ER/Golgi homeostasis disruption, ER stress, and blocked autophagosome clearance, linking its trafficking and genome integrity functions to neuronal survival.

   Evidence Conditional Rint1 knockout in mouse neuroprogenitors with ER stress markers, autophagy flux, and chromosome analysis

   PMID:26383973

   Open questions at the time

   • Whether ER stress is a direct consequence of trafficking failure or an independent RINT1 function was unresolved
   • Autophagosome clearance defect mechanism (fusion vs. lysosomal degradation) was not dissected
6. 2016 Medium

   Interaction with MSP58 at the nucleolus and repression of rRNA synthesis revealed an additional nuclear role for RINT1 in rDNA transcriptional regulation.

   Evidence Yeast two-hybrid, co-IP, ChIP at rDNA promoter, luciferase reporter assay, siRNA knockdown effects on rRNA levels

   PMID:27530925

   Open questions at the time

   • Finding from a single laboratory; independent confirmation is lacking
   • Physiological significance of rDNA repression by RINT1 in vivo is untested
   • Whether this function relates to its role in genome stability was not explored
7. 2019 Medium

   Bi-allelic RINT1 variants in patients established RINT1 as a disease gene, with patient fibroblasts showing defective Golgi-to-ER transport and impaired autophagic flux; interaction with NBAS and UVRAG linked RINT1 to nutrient-sensitive trafficking-autophagy switching via mTOR.

   Evidence Patient-derived fibroblast functional assays, Golgi morphology, autophagic flux measurement, protein interaction studies

   PMID:31204009

   Open questions at the time

   • Precise nature of mTOR-dependent UVRAG regulation through RINT1 was not mechanistically resolved
   • Whether NBAS and RINT1 function in the same complex or parallel pathways was unclear
   • Genotype–phenotype correlation across patients was limited
8. 2020 High

   Conditional retinal Rint1 knockout and genetic rescue by Trp53 deletion placed RINT1 upstream of p53-mediated apoptosis triggered by endogenous DNA damage, demonstrating its requirement for genome maintenance during neurodevelopment.

   Evidence Conditional knockout in mouse retinal progenitors, epistasis with Trp53 deletion, DNA damage markers, ERG visual function tests

   PMID:32850831

   Open questions at the time

   • Source of endogenous DNA damage (replication stress vs. oxidative damage) was not identified
   • Whether the apoptotic phenotype involves RINT1's trafficking or Rad50-interaction function was not distinguished
9. 2021 Medium

   Proteomics in pancreatic cancer cells revealed that RINT1 loss impairs SUMOylation, disrupts nucleocytoplasmic transport, and compromises the double-strand break response, expanding its genome-maintenance role to include regulation of the SUMO pathway.

   Evidence shRNA knockdown, quantitative proteomics and interactome analysis, xenograft model

   PMID:33531371

   Open questions at the time

   • SUMOylation connection is inferred from interactome data and not validated by direct SUMO-transfer assay
   • Whether SUMOylation defect is a direct or indirect consequence of RINT1 loss was not established
10. 2023 High

    Lipidomic and mitochondrial analyses of patient fibroblasts showed that RINT1 loss causes defective lipid-droplet biogenesis, abnormal phospholipid metabolism, mitochondrial depolarization, increased ROS, and aberrant cristae, extending its role to lipid and mitochondrial homeostasis.

    Evidence Lipidomic profiling, lipid-droplet imaging, ROS measurement, mitochondrial membrane potential assay, electron microscopy in patient fibroblasts

    PMID:37463447

    Open questions at the time

    • Whether lipid/mitochondrial defects are secondary to ER/Golgi trafficking failure or represent an independent function is unknown
    • Direct RINT1 interaction with lipid metabolism enzymes was not shown
11. 2025 Medium

    Disease-associated RINT1 missense mutants were shown to disrupt ER tether and SNARE complex binding, activate the UPR, impair autophagy, and cause lipid storage abnormalities in a Drosophila model, providing cross-species functional validation of the human disease mechanism.

    Evidence Immunoprecipitation of mutant RINT1 proteins, UPR gene expression, LC3-II turnover, Drosophila fat-body Rint1 knockdown

    PMID:40940405

    Open questions at the time

    • Whether specific mutants retain partial function is not quantitatively resolved
    • Drosophila model phenotype correspondence to mammalian disease tissue specificity is unclear
12. 2026 Medium

    Identification of RNF39-mediated K48-linked ubiquitination driving RINT1 proteasomal degradation and BRIP1-mediated acetylation at K728 promoting RINT1–RAD50 interaction and MRN-dependent homologous recombination established the post-translational regulatory logic governing RINT1 stability and DNA repair function.

    Evidence Co-IP and ubiquitination assays for RNF39; acetylation assays and HR repair readouts for BRIP1-RINT1-RAD50 axis; xenograft models

    PMID:41457280 PMID:41740833

    Open questions at the time

    • Whether RNF39-mediated degradation is signal-dependent (e.g., cell cycle or stress regulated) was not tested
    • Single-lab findings for both ubiquitination and acetylation; independent validation is lacking
    • Whether acetylation and ubiquitination are coordinated or antagonistic on the same RINT1 pool is unknown

• How RINT1 partitions between its distinct membrane-trafficking (ZW10–syntaxin 18 vs. COG), genome-stability (Rad50/MRN, telomere, checkpoint), nucleolar (rDNA), and metabolic (lipid/mitochondrial) functions—and whether these roles are mechanistically interdependent or independently regulated—remains the central unresolved question.
• No structural model of full-length RINT1 or any of its complexes exists
• Tissue-specific regulation and post-translational modification crosstalk are poorly understood
• Whether trafficking failure is the primary driver of downstream ER stress, lipid, and mitochondrial phenotypes has not been formally tested