Affinage

GADD45GIP1

Large ribosomal subunit protein mL64 · UniProt Q8TAE8

Round 2 corrected
Length
222 aa
Mass
25.4 kDa
Annotated
2026-04-28
42 papers in source corpus 10 papers cited in narrative 10 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GADD45GIP1 (CRIF1/mL64) is a mitochondrial large ribosomal subunit protein essential for the synthesis and insertion of oxidative phosphorylation (OxPhos) complex subunits into the inner mitochondrial membrane, as demonstrated by conditional knockout models in pancreatic beta cells and adipocytes where its loss causes progressive OxPhos dysfunction, impaired insulin secretion, and compensatory mitokine (GDF15/FGF21) secretion that systemically improves energy homeostasis (PMID:25660120, PMID:31925461). Beyond its mitochondrial role, GADD45GIP1 functions as a tumor-suppressive effector downstream of the transcriptional repressor NAC-1: its re-expression induces growth arrest, sensitizes ovarian cancer cells to paclitaxel and cisplatin by counteracting drug-induced senescence, and activates GADD45γ-dependent JNK/p38/caspase-3 apoptotic signaling (PMID:17804717, PMID:19305429, PMID:31490008). GADD45GIP1 is phosphorylated by casein kinase II at Ser-221, and the phosphomimetic S221E mutant promotes cell proliferation, indicating context-dependent regulation of growth (PMID:17069992). GADD45GIP1 also stabilizes the ribosomal protein RPL35 by inhibiting its polyubiquitination, thereby modulating PERK/eIF2α-mediated ER stress signaling (PMID:40604925).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2001 Medium

    Identification of GADD45GIP1 as a physical interactor of the CKIIβ regulatory subunit established it as a potential signaling target of the CKII kinase, opening the question of whether CKII phosphorylates it and with what functional consequence.

    Evidence Yeast two-hybrid screen and far-western overlay mapping the CKIIβ binding region

    PMID:11710515

    Open questions at the time
    • Single yeast two-hybrid study without in vivo validation of the interaction
    • Phosphorylation and functional relevance not yet tested
  2. 2006 High

    Demonstration that CKII phosphorylates GADD45GIP1 at Ser-221 and that this modification promotes cell proliferation resolved the functional consequence of the CKII interaction, establishing GADD45GIP1 as a growth-regulatory phosphoprotein.

    Evidence In vitro kinase assay, phosphoamino acid analysis, S221A/S221E mutagenesis with proliferation readout in COS7 cells

    PMID:17069992

    Open questions at the time
    • In vivo relevance of Ser-221 phosphorylation not tested
    • Downstream effectors of phospho-GADD45GIP1-driven proliferation not identified
  3. 2007 High

    Discovery that the BTB/POZ repressor NAC-1 transcriptionally silences GADD45GIP1, and that restoring GADD45GIP1 expression causes tumor growth arrest in vitro and in vivo, established GADD45GIP1 as a bona fide tumor-suppressive effector in the NAC-1 oncogenic pathway.

    Evidence SAGE, siRNA/overexpression epistasis, xenograft growth assays in SKOV3 and HeLa cells

    PMID:17804717

    Open questions at the time
    • Mechanism by which GADD45GIP1 enforces growth arrest not defined
    • Whether NAC-1 directly binds the GADD45GIP1 promoter not shown
  4. 2009 High

    Linking GADD45GIP1 to GADD45γ interaction and showing that this axis mediates paclitaxel sensitivity upon disruption of NAC-1 dimerization revealed the downstream apoptotic effector mechanism through which GADD45GIP1 sensitizes tumor cells to chemotherapy.

    Evidence Bidirectional genetic epistasis (shRNA, ectopic expression, dominant-negative BTB domain) with paclitaxel resistance assays in ovarian cancer cells

    PMID:19305429

    Open questions at the time
    • Structural basis of GADD45GIP1–GADD45γ interaction unknown
    • Whether GADD45GIP1 directly participates in MAPK cascade activation not resolved
  5. 2014 Medium

    Identification of the Drosophila ortholog dCRIF as essential for Dicer-2 stability and siRNA biogenesis broadened the functional repertoire of CRIF1 family proteins to include regulation of the RNAi machinery and antiviral defense.

    Evidence Drosophila genetic screen with loss-of-function mutants, siRNA biogenesis assays, co-immunoprecipitation of dCRIF–Dicer-2

    PMID:25483042

    Open questions at the time
    • Conservation of the Dicer-2-stabilizing function in mammalian GADD45GIP1 not tested
    • Mechanism of stabilization (chaperone-like vs. stoichiometric protection) not determined
  6. 2015 High

    Beta-cell-specific Crif1 knockout demonstrated that GADD45GIP1 is essential for mitochondrial OxPhos complex assembly, resolving the primary cell-autonomous function of the protein in energy metabolism and linking its loss to beta cell failure and impaired insulin secretion.

    Evidence Conditional Crif1 KO mouse, glucose tolerance and insulin secretion assays, electron microscopy of mitochondrial ultrastructure

    PMID:25660120

    Open questions at the time
    • Specific OxPhos complex subunits whose insertion depends on CRIF1 not individually mapped
    • Whether CRIF1 acts co-translationally at the mitoribosome or post-translationally not distinguished
  7. 2017 Medium

    Establishing that NAC1 promotes cisplatin resistance by suppressing GADD45GIP1 and thereby blocking drug-induced senescence expanded the tumor-suppressive role of GADD45GIP1 from paclitaxel to platinum-based chemotherapy and identified cellular senescence as a key effector phenotype.

    Evidence siRNA/shRNA and overexpression in SKOV3 and TOV-21G cells, cisplatin cytotoxicity and β-galactosidase senescence assays

    PMID:28599472

    Open questions at the time
    • Single-lab study; independent replication in additional cell lines or models needed
    • Molecular mechanism linking GADD45GIP1 to senescence induction not defined
  8. 2019 Medium

    Placement of GADD45GIP1 as the mediator connecting NAC-1 downregulation (by CRM197) to JNK/p38 MAPK activation and caspase-3-dependent apoptosis completed the signaling cascade from NAC-1 repression through GADD45GIP1 to cell death.

    Evidence CRM197 treatment in vitro and in vivo xenograft models, Western blotting of NAC-1/GADD45GIP1/JNK/p38/caspase-3 pathway

    PMID:31490008

    Open questions at the time
    • No direct epistasis rescue experiment to confirm GADD45GIP1 is required downstream of CRM197
    • Pathway placement relies on expression/activity correlations
  9. 2020 High

    Adipocyte-specific Crif1 deletion demonstrated that CRIF1 loss triggers the mitochondrial unfolded protein response and non-cell-autonomous metabolic benefits via GDF15 and FGF21 mitokine secretion, revealing a systemic endocrine signaling axis controlled by mitochondrial OxPhos fidelity.

    Evidence Adipocyte-specific Crif1 KO mice crossed with global Gdf15-KO and Fgf21-KO, RNA-seq, metabolic phenotyping, pharmacological OxPhos inhibition in 3T3-L1 cells

    PMID:31925461

    Open questions at the time
    • Whether the metabolic benefit is durable long-term or represents a compensatory acute response is not fully resolved
    • Direct mechanism linking mitochondrial UPR to GDF15/FGF21 transcriptional activation not defined
  10. 2025 Medium

    Discovery that GADD45GIP1 stabilizes RPL35 by blocking its polyubiquitination and that RPL35 loss activates PERK/eIF2α ER stress uncovered a previously unrecognized function of GADD45GIP1 in ribosomal protein quality control and ER stress modulation.

    Evidence IP/LC-MS/MS proteomics, ubiquitination assays, siRNA knockdown and overexpression rescue, PERK/eIF2α Western blotting in osteosarcoma cells

    PMID:40604925

    Open questions at the time
    • Single-lab study; awaits independent confirmation in non-cancer cell types
    • E3 ubiquitin ligase targeting RPL35 not identified
    • Relationship between GADD45GIP1's mitoribosomal role and its cytoplasmic RPL35-stabilizing function unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • Whether GADD45GIP1/CRIF1 acts co-translationally at the mitoribosome to insert OxPhos subunits versus as a post-translational chaperone, how its nuclear/cytoplasmic tumor-suppressive functions are coordinated with its mitochondrial role, and the structural basis for its diverse protein–protein interactions remain unresolved.
  • No structural model of GADD45GIP1 in context of the mitoribosome or any partner complex
  • Mechanism of dual localization (mitochondrial vs. nuclear) and how it is regulated is unknown
  • Whether the Dicer-2/RNAi role observed in Drosophila is conserved in mammals is untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 5 GO:0044183 protein folding chaperone 2
Localization
GO:0005634 nucleus 2 GO:0005739 mitochondrion 2
Pathway
R-HSA-1430728 Metabolism 2 R-HSA-162582 Signal Transduction 2 R-HSA-5357801 Programmed Cell Death 2 R-HSA-8953897 Cellular responses to stimuli 2
Partners
CSNK2BGADD45GNACC1RPL35
Complex memberships
mitochondrial large ribosomal subunit (39S)

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 GADD45GIP1 (then called CKBBP2) was identified as a binding partner of the CKIIβ regulatory subunit via yeast two-hybrid assay. The minimal binding region on CKIIβ for CKBBP2 was mapped to residues 67–130, distinct from binding sites for other CKIIβ interactors. Yeast two-hybrid mapping with truncation constructs; overlay (far-western) experiments Molecules and cells Medium 11710515
2006 GADD45GIP1 (CKBBP2/CRIF1) physically associates with the CKIIβ subunit and is phosphorylated by protein kinase CKII at serine-221. Phosphomimetic mutation S221E promotes cell proliferation, whereas the non-phosphorylatable S221A mutant does not, establishing CKII-mediated phosphorylation of GADD45GIP1 as a positive regulator of cell proliferation. Yeast two-hybrid, GST pull-down, in vitro kinase assay with recombinant CKII, phosphoamino acid analysis, site-directed mutagenesis (S221A and S221E), cell proliferation assay in COS7 cells Gene High 17069992
2007 NAC-1, a BTB/POZ transcription repressor, negatively regulates GADD45GIP1 transcription. NAC-1 knockdown in SKOV3 and HeLa cells induces GADD45GIP1 expression, while NAC-1 overexpression in NAC-1-negative cells suppresses it. Ectopic GADD45GIP1 expression causes growth arrest in tumor cells in vitro and in vivo, and partial rescue of dominant-negative NAC-1-induced growth inhibition by GADD45GIP1 knockdown establishes GADD45GIP1 as a downstream tumor-suppressive effector of the NAC-1 pathway. Serial analysis of gene expression (SAGE), siRNA knockdown, ectopic overexpression, dominant-negative NAC-1, in vitro and in vivo (xenograft) growth assays Cancer research High 17804717
2009 GADD45GIP1 interacts with GADD45γ (growth arrest and DNA-damage-inducible 45-gamma). Loss of GADD45GIP1 confers paclitaxel resistance in ovarian cancer cells, while ectopic GADD45GIP1 expression increases paclitaxel sensitivity. NAC-1 homodimerization suppresses the pathway; disruption of NAC-1 dimerization induces GADD45γ expression, which then interacts with GADD45GIP1, and GADD45γ knockdown partially restores paclitaxel resistance. shRNA knockdown, ectopic expression, dominant-negative BTB/POZ domain construct, ex vivo paclitaxel resistance assays, co-expression epistasis analysis Oncogene High 19305429
2014 The Drosophila ortholog of GADD45GIP1/CRIF1 (dCRIF) is required for RNAi efficiency and antiviral immunity. dCRIF loss-of-function mutants are deficient in siRNA biogenesis and RNAi-mediated knockdown. dCRIF physically interacts with and stabilizes the RNase III enzyme Dicer-2, identifying a conserved role for CRIF1 in regulating the RNAi machinery. Drosophila genetic screen, loss-of-function mutants, siRNA biogenesis assays, antiviral immunity assays, co-immunoprecipitation (dCRIF–Dicer-2 interaction) RNA biology Medium 25483042
2015 Beta-cell-specific deletion of Crif1 (Gadd45gip1) in mice causes progressive mitochondrial oxidative phosphorylation (OxPhos) dysfunction leading to impaired insulin secretion and beta cell failure, demonstrating that CRIF1 is essential for the synthesis and assembly of OxPhos complexes in the inner mitochondrial membrane of beta cells. Conditional (beta-cell-specific) Crif1 knockout mouse model, glucose tolerance tests, insulin secretion assays, ultrastructural electron microscopy of mitochondria Diabetologia High 25660120
2017 NAC1 suppresses GADD45GIP1 expression and promotes cisplatin resistance in ovarian cancer cells by inhibiting cisplatin-induced cellular senescence. NAC1 knockdown increases GADD45GIP1 expression and enhances senescence-dependent cisplatin cytotoxicity, while NAC1 overexpression in NAC1-negative cells reduces cisplatin sensitivity, establishing the NAC1/GADD45GIP1 axis as a regulator of drug-induced senescence. RNA interference (siRNA/shRNA), ectopic overexpression, cisplatin cytotoxicity assays, cellular senescence assays (β-galactosidase staining) in SKOV3 and TOV-21G cells Oncology letters Medium 28599472
2019 CRM197, a specific HB-EGF inhibitor, reverses paclitaxel resistance in ovarian cancer cells by downregulating NAC-1, leading to upregulation of GADD45GIP1, which in turn activates the pro-apoptotic JNK/p38 MAPK pathway and increases caspase-3 activity. This positions GADD45GIP1 as a mediator linking NAC-1 suppression to apoptotic signaling. In vitro cell viability assays, in vivo xenograft models, Western blotting for NAC-1/GADD45GIP1/JNK/p38/caspase-3 pathway components Cancer medicine Medium 31490008
2020 Adipocyte-specific deletion of Crif1 (Gadd45gip1) reduces adipocyte OxPhos function, triggering the mitochondrial unfolded protein response and upregulating secretion of mitokines GDF15 and FGF21. These mitokines mediate systemic metabolic benefits including resistance to diet-induced obesity and improved glucose tolerance, demonstrating that CRIF1 in adipocytes regulates both cell-autonomous and non-cell-autonomous energy homeostasis via mitokine signaling. Adipocyte-specific Crif1 KO mice (AdKO), global Gdf15 and Fgf21 KO crosses (AdGKO, AdFKO), RNA sequencing, metabolic phenotyping (weight, EE, glucose tolerance), pharmacological OxPhos inhibition in 3T3L1 cells Diabetologia High 31925461
2025 GADD45GIP1 physically interacts with RPL35 (ribosomal protein L35), identified by co-immunoprecipitation and LC-MS/MS proteomics. GADD45GIP1 stabilizes RPL35 by inhibiting its polyubiquitination and proteasomal degradation. RPL35 knockdown activates the PERK/eIF2α ER stress pathway, and RPL35 overexpression rescues the reduced cell viability caused by GADD45GIP1 knockdown, establishing GADD45GIP1 as a regulator of RPL35 stability that modulates ER stress in osteosarcoma. IP/LC-MS/MS proteomics, siRNA knockdown, overexpression, ubiquitination assay (polyubiquitination), Western blotting for PERK/eIF2α pathway, cell viability and migration assays in vitro and in vivo Cancer cell international Medium 40604925

Source papers

Stage 0 corpus · 42 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2015 The BioPlex Network: A Systematic Exploration of the Human Interactome. Cell 1118 26186194
2017 Architecture of the human interactome defines protein communities and disease networks. Nature 1085 28514442
2015 A human interactome in three quantitative dimensions organized by stoichiometries and abundances. Cell 1015 26496610
2014 A proteome-scale map of the human interactome network. Cell 977 25416956
2020 A reference map of the human binary protein interactome. Nature 849 32296183
2021 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. Cell 705 33961781
2012 A census of human soluble protein complexes. Cell 689 22939629
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
2022 OpenCell: Endogenous tagging for the cartography of human cellular organization. Science (New York, N.Y.) 432 35271311
2010 Dynamics of cullin-RING ubiquitin ligase network revealed by systematic quantitative proteomics. Cell 318 21145461
2014 Structure of the large ribosomal subunit from human mitochondria. Science (New York, N.Y.) 262 25278503
2021 Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context. Cell metabolism 239 34800366
2007 hORFeome v3.1: a resource of human open reading frames representing over 10,000 human genes. Genomics 222 17207965
2016 Structure and Function of the Mitochondrial Ribosome. Annual review of biochemistry 217 27023846
2018 An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations. Nature communications 201 29568061
2012 Mitochondrial nucleoid interacting proteins support mitochondrial protein synthesis. Nucleic acids research 173 22453275
2010 A functional peptidyl-tRNA hydrolase, ICT1, has been recruited into the human mitochondrial ribosome. The EMBO journal 153 20186120
2015 BioID-based Identification of Skp Cullin F-box (SCF)β-TrCP1/2 E3 Ligase Substrates. Molecular & cellular proteomics : MCP 149 25900982
2020 A High-Density Human Mitochondrial Proximity Interaction Network. Cell metabolism 148 32877691
2019 Mapping the proximity interaction network of the Rho-family GTPases reveals signalling pathways and regulatory mechanisms. Nature cell biology 137 31871319
2017 RNA-binding activity of TRIM25 is mediated by its PRY/SPRY domain and is required for ubiquitination. BMC biology 135 29117863
2011 Interactions of pathological hallmark proteins: tubulin polymerization promoting protein/p25, beta-amyloid, and alpha-synuclein. The Journal of biological chemistry 131 21832049
2020 PROTAC-mediated degradation reveals a non-catalytic function of AURORA-A kinase. Nature chemical biology 129 32989298
2022 Human transcription factor protein interaction networks. Nature communications 123 35140242
2014 Clozapine-induced agranulocytosis is associated with rare HLA-DQB1 and HLA-B alleles. Nature communications 123 25187353
2004 A protein interaction framework for human mRNA degradation. Genome research 123 15231747
2015 Proteomic analyses reveal distinct chromatin-associated and soluble transcription factor complexes. Molecular systems biology 120 25609649
2019 Systematic bromodomain protein screens identify homologous recombination and R-loop suppression pathways involved in genome integrity. Genes & development 110 31753913
2009 NAC-1, a potential stem cell pluripotency factor, contributes to paclitaxel resistance in ovarian cancer through inactivating Gadd45 pathway. Oncogene 72 19305429
1995 Use of reporter genes to identify recessive trans-acting mutations specifically involved in the regulation of Aspergillus nidulans penicillin biosynthesis genes. Journal of bacteriology 67 7677843
2007 NAC-1 controls cell growth and survival by repressing transcription of Gadd45GIP1, a candidate tumor suppressor. Cancer research 64 17804717
2020 An adipocyte-specific defect in oxidative phosphorylation increases systemic energy expenditure and protects against diet-induced obesity in mouse models. Diabetologia 55 31925461
2015 Disruption of CR6-interacting factor-1 (CRIF1) in mouse islet beta cells leads to mitochondrial diabetes with progressive beta cell failure. Diabetologia 22 25660120
2019 CRM197 reverses paclitaxel resistance by inhibiting the NAC-1/Gadd45 pathway in paclitaxel-resistant ovarian cancer cells. Cancer medicine 19 31490008
2006 Phosphorylation of CKBBP2/CRIF1 by protein kinase CKII promotes cell proliferation. Gene 10 17069992
2001 Mapping of the interaction domain of the protein kinase CKII beta subunit with target proteins. Molecules and cells 10 11710515
2017 Nucleus accumbens-1/GADD45GIP1 axis mediates cisplatin resistance through cellular senescence in ovarian cancer. Oncology letters 9 28599472
2014 Requirement for CRIF1 in RNA interference and Dicer-2 stability. RNA biology 5 25483042
2025 GADD45GIP1 promotes osteosarcoma progression by modulating RPL35 ubiquitination and alleviating endoplasmic reticulum stress via the PERK/eIF2α pathway. Cancer cell international 2 40604925
2026 Unresolved questions on the GADD45GIP1-RPL35 axis in osteosarcoma: mechanistic links to ER stress and therapeutic targeting. Cancer cell international 0 41606585