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## Question

# Gene Research for Functional Annotation

## ⚠️ CRITICAL: Gene/Protein Identification Context

**BEFORE YOU BEGIN RESEARCH:** You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

### Target Gene/Protein Identity (from UniProt):
- **UniProt Accession:** Q7Z6M2
- **Protein Description:** RecName: Full=F-box only protein 33;
- **Gene Information:** Name=FBXO33; Synonyms=FBX33;
- **Organism (full):** Homo sapiens (Human).
- **Protein Family:** Not specified in UniProt
- **Key Domains:** F-box-like_dom_sf. (IPR036047); F-box_dom. (IPR001810); LRR_dom_sf. (IPR032675); F-box-like (PF12937)

### MANDATORY VERIFICATION STEPS:

1. **Check if the gene symbol "FBXO33" matches the protein description above**
2. **Verify the organism is correct:** Homo sapiens (Human).
3. **Check if protein family/domains align with what you find in literature**
4. **If you find literature for a DIFFERENT gene with the same or similar symbol, STOP**

### If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

**DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE.** Instead:
- State clearly: "The gene symbol 'FBXO33' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

### Research Target:

Please provide a comprehensive research report on the gene **FBXO33** (gene ID: FBXO33, UniProt: Q7Z6M2) in human.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

## Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

# Gene Research for Functional Annotation

## ⚠️ CRITICAL: Gene/Protein Identification Context

**BEFORE YOU BEGIN RESEARCH:** You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

### Target Gene/Protein Identity (from UniProt):
- **UniProt Accession:** Q7Z6M2
- **Protein Description:** RecName: Full=F-box only protein 33;
- **Gene Information:** Name=FBXO33; Synonyms=FBX33;
- **Organism (full):** Homo sapiens (Human).
- **Protein Family:** Not specified in UniProt
- **Key Domains:** F-box-like_dom_sf. (IPR036047); F-box_dom. (IPR001810); LRR_dom_sf. (IPR032675); F-box-like (PF12937)

### MANDATORY VERIFICATION STEPS:

1. **Check if the gene symbol "FBXO33" matches the protein description above**
2. **Verify the organism is correct:** Homo sapiens (Human).
3. **Check if protein family/domains align with what you find in literature**
4. **If you find literature for a DIFFERENT gene with the same or similar symbol, STOP**

### If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

**DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE.** Instead:
- State clearly: "The gene symbol 'FBXO33' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

### Research Target:

Please provide a comprehensive research report on the gene **FBXO33** (gene ID: FBXO33, UniProt: Q7Z6M2) in human.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

## Research Report: Human **FBXO33** (UniProt **Q7Z6M2**) — Functional Annotation

### 0) Identity verification (critical)
The research target is **human FBXO33** (synonym **FBX33**) encoding **F-box only protein 33**, consistent across the primary literature retrieved here (e.g., papers explicitly naming “F-box only protein 33 (FBXO33)” and studying it in human cell models and/or human tissues). FBXO33 is described as an **F-box protein functioning within a Cullin-1 (CUL1)-based Cullin-RING ubiquitin ligase (CRL), i.e., an SCF-like E3 ligase**, consistent with the UniProt-provided domain context (F-box and LRR-like features) and with its experimentally demonstrated roles as a substrate-recruiting factor for ubiquitination and proteasomal degradation. (chen2019fipoqfbxo33acullin‐1‐based pages 1-2, chen2019fipoqfbxo33acullin‐1‐based pages 11-13)

### 1) Key concepts and current understanding

#### 1.1 What an F-box protein does (context for FBXO33)
F-box proteins are typically the **substrate-recognition modules** of **SCF (SKP1–CUL1–RBX1) E3 ubiquitin ligases**, coupling a target protein (“substrate”) to the CUL1-based ubiquitin ligase machinery so the substrate can be polyubiquitinated and, often, degraded by the proteasome. In the polyglutamine disease context, Chen et al. explicitly frame **FBXO33 as an F-box substrate receptor acting in a CUL1-based CRL pathway**, with functional data supporting recruitment of an expanded polyQ substrate for ubiquitination and clearance. (chen2019fipoqfbxo33acullin‐1‐based pages 1-2, chen2019fipoqfbxo33acullin‐1‐based pages 11-13)

#### 1.2 FBXO33’s inferred primary molecular role
Across the mechanistic studies retrieved, the **primary function** supported for FBXO33 is:
- **E3 ubiquitin ligase substrate adaptor/receptor** within a **CUL1-based CRL/SCF-like complex**, promoting ubiquitination of specific substrates and affecting their stability/aggregation. (chen2019fipoqfbxo33acullin‐1‐based pages 1-2, chen2019fipoqfbxo33acullin‐1‐based pages 11-13)

FBXO33 is therefore **not** an enzyme catalyzing a small-molecule reaction; its “substrate specificity” is **protein-substrate specificity**, determined by binding interactions (e.g., defined domains/regions of substrates such as p53 or YBX1). (wu2025lactylationdriventranscriptionalactivation pages 7-10, xiao2023splicingfactorybx1 pages 11-14)

### 2) Experimentally supported substrates/interactors, pathways, and localization

#### 2.1 Protein quality control / proteostasis: ATXN3/polyQ (SCA3) as a substrate-like target
A foundational mechanistic study (Chen et al., 2019; *Journal of Neurochemistry*, **June 2019**, DOI: **10.1111/jnc.14669**) provides evidence that FBXO33 modulates ubiquitination and aggregation properties of expanded polyglutamine ataxin-3 constructs:
- **Selective association with expanded polyQ**: FBXO33 **co-immunoprecipitates preferentially** with aggregate-forming **expanded Q78** ataxin-3 construct (EGFP-SCA3tr-Q78) but not with unexpanded Q27. (chen2019fipoqfbxo33acullin‐1‐based pages 11-13)
- **Promotes ubiquitination and reduces aggregation**: FBXO33 overexpression increases solubility of Q78 and reduces aggregates (filter retardation/aggregate assays), with typical replicate reporting **n = 3** for key cell-model assays. (chen2019fipoqfbxo33acullin‐1‐based pages 11-13)
- **Proteasome-dependent mechanism**: The anti-aggregation effect is **blocked by a proteasome inhibitor (lactacystin)** but not by chloroquine (lysosome inhibitor), indicating a primary **proteasome/UPS** dependency. (chen2019fipoqfbxo33acullin‐1‐based pages 9-11)
- **Subcellular localization**: FBXO33 (with CUL1 in the same experimental context) is reported to localize to **both nucleus and cytoplasm**. (chen2019fipoqfbxo33acullin‐1‐based pages 11-13)

**Interpretation:** These data support FBXO33’s role in a **CUL1-based ubiquitination pathway** contributing to proteostasis by promoting ubiquitination and reducing toxic aggregation/insolubility of expanded polyQ proteins. (chen2019fipoqfbxo33acullin‐1‐based pages 1-2, chen2019fipoqfbxo33acullin‐1‐based pages 11-13)

#### 2.2 Aging/bone biology: FBXO33–YBX1 axis (substrate/interactor) and pharmacologic stabilization
A recent high-impact study (Xiao et al., 2023; *The EMBO Journal*, **March 2023**, DOI: **10.15252/embj.2022111762**) provides evidence that FBXO33 interacts with YBX1 and is implicated in **ubiquitin-dependent degradation of YBX1**, with downstream relevance to bone marrow stromal cell (BMSC) aging:
- **Physical interaction + binding-site mapping**: Co-immunoprecipitation (co-IP) supports an FBXO33–YBX1 interaction; YBX1 mapping suggests amino acids **42–53** (“pocket”) and **128–322** (C-terminus) are important for FBXO33 binding. (xiao2023splicingfactorybx1 pages 11-14)
- **Compound mechanism (sciadopitysin)**: Sciadopitysin **slows YBX1 degradation** in cycloheximide chase and **decreases YBX1 ubiquitination** (MG132-assisted ubiquitination assays), and is reported to reduce **FBXO33 protein** and **suppress the FBXO33–YBX1 co-IP signal**, consistent with stabilizing YBX1 by interfering with FBXO33-mediated ubiquitination/degradation. (xiao2023splicingfactorybx1 pages 11-14)
- **In vivo quantitative bone outcomes**: With sciadopitysin (treatment group **n = 8**), the study reports improvements in bone parameters including increased **BV/TV**, **Tb.Th**, and **Tb.N**, increased osteoblast-related measures (including **MAR** and **BFR**), fewer adipocytes, and no change in osteoclast numbers—consistent with a functional outcome of stabilizing YBX1 in aging bone contexts. (xiao2023splicingfactorybx1 pages 11-14)

**Interpretation:** This positions FBXO33 as a regulator of a nuclear splicing factor (YBX1) and connects FBXO33 biology to **aging-associated stem/stromal cell fate** and bone phenotypes, providing a concrete example of a **small-molecule intervention** acting on a pathway in which FBXO33 is a key node. (xiao2023splicingfactorybx1 pages 11-14, xiao2023splicingfactorybx1 pages 14-15)

#### 2.3 Cancer: FBXO33 targeting of p53 (wild-type) and EMT/metastasis phenotypes (2025 mechanistic extension)
A mechanistic cancer study (Wu et al., 2025; *Cell Death & Disease*, **February 2025**, DOI: **10.1038/s41419-025-07372-y**) reports that FBXO33 binds p53 and regulates p53 stability via ubiquitination in gallbladder cancer:
- **Binding and domain mapping**: Co-IP indicates **FBXO33 binds p53**, with interaction mapped to **p53 (aa 100–293)** and **FBXO33 (aa 111–555)**. (wu2025lactylationdriventranscriptionalactivation pages 7-10)
- **Ubiquitination sites**: FBXO33 modulates p53 polyubiquitination at **K291 and K292**. (wu2025lactylationdriventranscriptionalactivation pages 7-10, wu2025lactylationdriventranscriptionalactivation pages 1-2)
- **Post-transcriptional control**: FBXO33 perturbation changes p53 protein stability without altering p53 mRNA; MG132 reverses FBXO33-dependent p53 reduction and CHX chase supports altered p53 half-life. (wu2025lactylationdriventranscriptionalactivation pages 7-10)
- **Wild-type preference**: The study reports FBXO33 preferentially increases ubiquitination of **wild-type p53** relative to common mutant p53 variants. (wu2025lactylationdriventranscriptionalactivation pages 7-10)
- **Clinical sample datapoint**: In a small described subset, **11 cases** showed FBXO33 higher in cancer than adjacent tissue while p53 was higher in adjacent tissue, consistent with an inverse relationship. (wu2025lactylationdriventranscriptionalactivation pages 7-10)

**Interpretation:** While outside the requested 2023–2024 window, this provides a detailed mechanistic model of FBXO33 substrate selection (p53) and illustrates that FBXO33 may act as an **oncogenic driver** in some contexts by destabilizing tumor suppressors. (wu2025lactylationdriventranscriptionalactivation pages 7-10, wu2025lactylationdriventranscriptionalactivation pages 1-2)

#### 2.4 Cancer: MYC ubiquitination/degradation and metastasis suppression in NSCLC (2024)
Wei et al. (2024; *Frontiers in Bioscience*, **August 2024**, DOI: **10.31083/j.fbl2908296**) reports that FBXO33 suppresses stemness/metastasis traits in non-small-cell lung cancer (NSCLC) via MYC:
- The paper’s central claim is that FBXO33 promotes **ubiquitination and degradation of MYC**, reducing stem cell-like properties and metastasis-related behaviors in NSCLC models. (wei2024theubiquitine3 pages 1-1)

**Evidence limitation note:** In the retrieved text snippet, detailed effect sizes (e.g., hazard ratios, fold-changes, quantitative assay readouts) were not accessible; thus this report treats the MYC mechanism as supported at the level of the paper’s stated results but cannot extract additional numerical statistics from the available excerpt. (wei2024theubiquitine3 pages 1-1)

#### 2.5 Cardiac biology: hypertrophy-modulating CRL component (screen-level evidence)
Fischer et al. (2023; *Frontiers in Physiology*, **March 2023**, DOI: **10.3389/fphys.2023.1134339**) identifies Fbxo33 (rat ortholog) as a hypertrophy-modulating gene in primary cardiomyocytes:
- **siRNA depletion increased cell size** in phenylephrine-stimulated neonatal rat cardiomyocytes (reported **1.31 ± 0.04**, **p < 0.001** vs control). (fischer2023identificationofhypertrophymodulating pages 6-8)
- **Protein synthesis increased** by 3H-isoleucine incorporation (reported **1.58 ± 0.06**, **p < 0.001**). (fischer2023identificationofhypertrophymodulating pages 6-8)

**Interpretation:** This is functional-genomics evidence that decreasing Fbxo33 activity can promote hypertrophic growth programs in cardiomyocytes; it does not identify substrates, but supports that FBXO33-associated CRL activity is relevant in cardiac cell-size control. (fischer2023identificationofhypertrophymodulating pages 6-8)

### 3) Recent developments (prioritizing 2023–2024)

#### 3.1 2023: FBXO33 in an actionable aging-bone pathway (YBX1 stabilization)
The strongest 2023 advance in this corpus is the **FBXO33–YBX1 axis** as a concrete mechanistic link between ubiquitin-mediated protein turnover and BMSC fate during aging, alongside an experimental small-molecule (sciadopitysin) that stabilizes YBX1 by interfering with this axis and improving bone microarchitecture metrics. (xiao2023splicingfactorybx1 pages 11-14, xiao2023splicingfactorybx1 pages 14-15)

#### 3.2 2023: Systems-level functional screening of CRL components in heart
The 2023 cardiomyocyte screen extends FBXO33 relevance beyond cancer/neurodegeneration to **hypertrophic remodeling**, with clear quantitative outcomes (effect sizes and p-values) for knockdown phenotypes. (fischer2023identificationofhypertrophymodulating pages 6-8)

#### 3.3 2024: Cancer metastasis suppression via MYC degradation
The 2024 NSCLC study positions FBXO33 as a potential **tumor suppressive E3 substrate adaptor** in that disease context by promoting degradation of an oncogenic transcription factor (MYC). (wei2024theubiquitine3 pages 1-1)

### 4) Current applications and real-world implementations

#### 4.1 Translational application: pathway-guided small-molecule intervention (bone aging)
A direct “implementation-like” example is the use of **sciadopitysin** in an in vivo aging/bone context, where the compound stabilizes YBX1 and is associated with improved bone structural parameters (e.g., BV/TV, Tb.Th, Tb.N) with **n = 8** in the in vivo group described in the retrieved text. This supports the concept that modulating protein stability through an FBXO33-linked axis can yield measurable physiological outcomes. (xiao2023splicingfactorybx1 pages 11-14)

#### 4.2 Translational application: cancer biology and biomarker hypotheses
The cancer literature indicates FBXO33 may be context-dependent—potentially **tumor suppressive** via MYC degradation in NSCLC (2024) but **oncogenic** via p53 destabilization in gallbladder cancer (2025). Such context dependence is typical of ubiquitin system substrate adaptors and implies that any biomarker/therapeutic use would require tumor-type and p53/MYC context stratification. (wei2024theubiquitine3 pages 1-1, wu2025lactylationdriventranscriptionalactivation pages 7-10)

#### 4.3 Human genetics/association integration (Open Targets)
Open Targets aggregates human genetic and functional evidence linking FBXO33 (ENSG00000165355) to several traits/diseases including **insomnia**, **smoking initiation**, **glomerulonephritis**, and others, with association scores on the order of ~0.23–0.28 and evidence counts of 5 in the tool output. These associations are useful for hypothesis generation but do not, on their own, specify molecular mechanism. (OpenTargets Search: -FBXO33)

Open Targets URL (target page): https://platform.opentargets.org/target/ENSG00000165355 (OpenTargets Search: -FBXO33)

### 5) Expert opinions and authoritative analysis (from the cited sources)

- **Mechanistic substrate-adaptor framing (proteostasis/neurodegeneration):** Chen et al. explicitly treat FBXO33 as a **CUL1-based CRL/SCF pathway component** with a substrate-receptor role affecting ubiquitination and toxicity of an expanded polyQ protein, reflecting the canonical expert understanding of how F-box proteins contribute to proteostasis. (chen2019fipoqfbxo33acullin‐1‐based pages 1-2, chen2019fipoqfbxo33acullin‐1‐based pages 11-13)
- **Aging/BMSC fate:** Xiao et al. provide an interpretation that pharmacologic stabilization of YBX1 can work by preventing its interaction with the ubiquitin ligase FBXO33, integrating splicing-factor biology, proteostasis, and aging phenotypes into a coherent pathway model. (xiao2023splicingfactorybx1 pages 11-14, xiao2023splicingfactorybx1 pages 14-15)
- **Cancer context dependence:** Wu et al. explicitly interpret FBXO33 as promoting metastasis in gallbladder cancer via p53 polyubiquitination, while also referencing that FBXO33 can act oppositely in NSCLC via MYC degradation; together these studies support the expert view that substrate adaptors can have **opposing roles depending on dominant substrates in a given cellular context**. (wu2025lactylationdriventranscriptionalactivation pages 1-2, wu2025lactylationdriventranscriptionalactivation pages 13-14)

### 6) Key statistics and data points (recent studies)
- **Cardiomyocyte hypertrophy screen (2023):** Fbxo33 knockdown increased PE-stimulated cardiomyocyte size to **1.31 ± 0.04 (p < 0.001)** and increased protein synthesis to **1.58 ± 0.06 (p < 0.001)**. (fischer2023identificationofhypertrophymodulating pages 6-8)
- **BMSC/bone aging intervention (2023):** sciadopitysin in vivo group size **n = 8**, with multiple bone-formation readouts reported as increased (BV/TV, Tb.Th, Tb.N, MAR, BFR) and adipocytes decreased. (xiao2023splicingfactorybx1 pages 11-14)
- **Gallbladder cancer mechanistic cancer study (2025):** **82** paraffin-embedded tumor specimens analyzed; **11** paired cases noted for inverse FBXO33 vs p53 expression trend; ubiquitination mapped to p53 **K291/K292** and binding mapped to defined p53/FBXO33 regions. (wu2025lactylationdriventranscriptionalactivation pages 7-10, wu2025lactylationdriventranscriptionalactivation pages 1-2)
- **PolyQ/ATXN3 cell-model experiments (2019):** key assays often reported with **n = 3** replicates; FBXO33 localization observed in **nucleus and cytoplasm**; proteasome inhibitor lactacystin blocks FBXO33-mediated effects. (chen2019fipoqfbxo33acullin‐1‐based pages 9-11, chen2019fipoqfbxo33acullin‐1‐based pages 11-13)

### 7) Consolidated evidence map
The following table consolidates the best-supported functional claims and the highest-value sources (including DOIs/URLs and accessible quantitative details).

| Claim/function | Evidence type/model | Key quantitative/statistical detail | Primary source (first author year, journal) | URL/DOI |
|---|---|---|---|---|
| FBXO33 acts as an E3 ligase/substrate receptor that binds wild-type p53 and promotes its polyubiquitination and proteasomal degradation, driving EMT/metastatic traits in gallbladder cancer | Human gallbladder cancer study; co-IP, ubiquitination assays, CHX chase, MG132 rescue, domain mapping, xenografts, clinical specimens | 82 paraffin-embedded tumor specimens analyzed; 11 paired cases showed FBXO33 higher in tumor while p53 was higher in adjacent tissue; p53 half-life was longer after sh-FBXO33 and shorter after Flag-FBXO33; binding mapped to p53 aa100-293 and FBXO33 aa111-555; ubiquitination at p53 K291/K292; knockdown reduced migration/EMT and tumor growth (wu2025lactylationdriventranscriptionalactivation pages 7-10, wu2025lactylationdriventranscriptionalactivation pages 1-2, wu2025lactylationdriventranscriptionalactivation pages 4-7, wu2025lactylationdriventranscriptionalactivation pages 13-14) | Wu 2025, *Cell Death & Disease* | https://doi.org/10.1038/s41419-025-07372-y |
| FBXO33 suppresses stem cell-like properties and metastasis in NSCLC by promoting ubiquitination and degradation of MYC | Human NSCLC study; title/abstract-level evidence from peer-reviewed primary paper | Paper reports FBXO33 is low in NSCLC and inversely correlated with overall survival; overexpression promoted MYC ubiquitination/degradation and suppressed proliferation, migration, invasion, and stemness, but detailed fold-changes/HRs were not available in retrieved evidence (wei2024theubiquitine3 pages 1-1, wu2025lactylationdriventranscriptionalactivation pages 13-14) | Wei 2024, *Frontiers in Bioscience* | https://doi.org/10.31083/j.fbl2908296 |
| FBXO33 is a Cul1-based F-box ligase component that modulates ubiquitination, solubility, and aggregation of expanded ATXN3/polyQ proteins | Human SK-N-MC cells plus Drosophila genetic modifier work; co-IP, overexpression, ubiquitination assays, filter retardation, inhibitor studies, localization | FBXO33 overexpression increased SDS-soluble SCA3tr-Q78 and reduced filter-retardation-detected aggregates (n=3); selectively co-immunoprecipitated with expanded Q78 but not Q27; effect was blocked by proteasome inhibitor lactacystin, not chloroquine; Cul1 and FBXO33 localized to both nucleus and cytoplasm; co-expression reduced fraction of cells with polyQ aggregates (chen2019fipoqfbxo33acullin‐1‐based pages 9-11, chen2019fipoqfbxo33acullin‐1‐based pages 7-9, chen2019fipoqfbxo33acullin‐1‐based pages 1-2, chen2019fipoqfbxo33acullin‐1‐based pages 11-13, chen2019fipoqfbxo33acullin‐1‐based pages 4-6) | Chen 2019, *Journal of Neurochemistry* | https://doi.org/10.1111/jnc.14669 |
| FBXO33 interacts with YBX1 and contributes to YBX1 ubiquitination-dependent degradation; sciadopitysin stabilizes YBX1 partly by disrupting the FBXO33-YBX1 axis | Human/mouse BMSC aging study; co-IP with deletion mapping, CHX chase, ubiquitination assays with MG132, pharmacologic stabilization | YBX1 regions aa42-53 and aa128-322 were required for FBXO33 binding; sciadopitysin slowed YBX1 degradation, decreased YBX1 ubiquitination, lowered FBXO33 protein, and reduced FBXO33-YBX1 co-IP signal; in vivo treatment group n=8 showed increased BV/TV, Tb.Th, Tb.N, osteoblast numbers, MAR, and BFR, with fewer adipocytes and no osteoclast change (xiao2023splicingfactorybx1 pages 11-14, xiao2022orchestrationofalternative pages 11-14, xiao2023splicingfactorybx1 pages 14-15) | Xiao 2023, *The EMBO Journal* | https://doi.org/10.15252/embj.2022111762 |
| FBXO33 is a negative regulator of cardiomyocyte hypertrophy in a functional screen | siRNA screen in neonatal rat cardiomyocytes with automated microscopy and 3H-isoleucine incorporation | Fbxo33 knockdown increased mean cell size to 1.31 ± 0.04 under PE treatment (p < 0.001) and increased 3H-isoleucine incorporation to 1.58 ± 0.06 (p < 0.001), indicating enhanced hypertrophic growth when Fbxo33 is depleted (fischer2023identificationofhypertrophymodulating pages 6-8) | Fischer 2023, *Frontiers in Physiology* | https://doi.org/10.3389/fphys.2023.1134339 |
| Human genetics/association resources link FBXO33 to several traits and diseases, but these are association-level signals rather than mechanistic functional proof | Open Targets integrated disease-target evidence | Open Targets reported evidence sizes of 5 for insomnia, smoking initiation, disease of peritoneum, abnormality of the gastrointestinal tract, and glomerulonephritis; association scores included ~0.260 for insomnia, ~0.258 for smoking initiation, ~0.235 for disease of peritoneum/GI abnormality, and ~0.283 for glomerulonephritis (OpenTargets Search: -FBXO33) | Open Targets Platform, accessed via tool context | https://platform.opentargets.org/target/ENSG00000165355 |


*Table: This table summarizes the main experimentally supported functions and disease links for human FBXO33, emphasizing direct substrate/interactor evidence, model systems, and quantitative findings. It is useful for distinguishing strong mechanistic evidence from broader association-level annotations.*

### 8) Overall conclusion (functional annotation)
The most defensible current functional annotation for **human FBXO33 (Q7Z6M2)** based on the retrieved evidence is that it is an **F-box substrate adaptor of a CUL1-based CRL/SCF-like ubiquitin ligase**, functioning primarily to **select specific protein substrates (or substrate-like targets)** for ubiquitination and downstream consequences including proteasomal degradation or altered solubility/aggregation. Mechanistically supported interacting substrates include **expanded ATXN3/polyQ** (proteostasis, nucleus/cytoplasm), **YBX1** (ubiquitin-dependent stability; BMSC aging and bone phenotypes), and **p53** (wild-type preference; EMT/metastasis phenotypes in gallbladder cancer). A 2024 study further supports a role for FBXO33 in **MYC ubiquitination/degradation** and suppression of stemness/metastasis in NSCLC, though quantitative details were not extractable from the available excerpt. (chen2019fipoqfbxo33acullin‐1‐based pages 11-13, xiao2023splicingfactorybx1 pages 11-14, wu2025lactylationdriventranscriptionalactivation pages 7-10, wei2024theubiquitine3 pages 1-1)

### 9) Evidence gaps (what cannot be concluded from retrieved text)
- The retrieved corpus does not provide a full, authoritative **UniProt/InterPro** text extract within the tool context, so domain statements beyond the user-provided UniProt identifiers are treated as **consistent background** rather than newly evidenced here.
- For the **Wei 2024 NSCLC/MYC** study, the current state contains only bibliographic/title/abstract-level evidence; detailed statistics (HRs, fold-change expression, exact assay values) would require full-text extraction beyond what was retrieved here. (wei2024theubiquitine3 pages 1-1)

### 10) Key primary sources (publication date, URL)
- Xiao et al., **Mar 2023**, *The EMBO Journal*: https://doi.org/10.15252/embj.2022111762 (xiao2023splicingfactorybx1 pages 11-14)
- Fischer et al., **Mar 2023**, *Frontiers in Physiology*: https://doi.org/10.3389/fphys.2023.1134339 (fischer2023identificationofhypertrophymodulating pages 6-8)
- Wei et al., **Aug 2024**, *Frontiers in Bioscience*: https://doi.org/10.31083/j.fbl2908296 (wei2024theubiquitine3 pages 1-1)
- Chen et al., **Jun 2019**, *Journal of Neurochemistry*: https://doi.org/10.1111/jnc.14669 (chen2019fipoqfbxo33acullin‐1‐based pages 11-13)
- Wu et al., **Feb 2025**, *Cell Death & Disease*: https://doi.org/10.1038/s41419-025-07372-y (wu2025lactylationdriventranscriptionalactivation pages 7-10)
- Open Targets (target ENSG00000165355): https://platform.opentargets.org/target/ENSG00000165355 (OpenTargets Search: -FBXO33)

References

1. (chen2019fipoqfbxo33acullin‐1‐based pages 1-2): Zhefan Stephen Chen, Azaria Kam Yan Wong, Tat Cheung Cheng, Alex Chun Koon, and Ho Yin Edwin Chan. Fipoq/fbxo33, a cullin‐1‐based ubiquitin ligase complex component modulates ubiquitination and solubility of polyglutamine disease protein. Journal of Neurochemistry, 149:781-798, Jun 2019. URL: https://doi.org/10.1111/jnc.14669, doi:10.1111/jnc.14669. This article has 35 citations and is from a domain leading peer-reviewed journal.

2. (chen2019fipoqfbxo33acullin‐1‐based pages 11-13): Zhefan Stephen Chen, Azaria Kam Yan Wong, Tat Cheung Cheng, Alex Chun Koon, and Ho Yin Edwin Chan. Fipoq/fbxo33, a cullin‐1‐based ubiquitin ligase complex component modulates ubiquitination and solubility of polyglutamine disease protein. Journal of Neurochemistry, 149:781-798, Jun 2019. URL: https://doi.org/10.1111/jnc.14669, doi:10.1111/jnc.14669. This article has 35 citations and is from a domain leading peer-reviewed journal.

3. (wu2025lactylationdriventranscriptionalactivation pages 7-10): Zhenheng Wu, You Peng, Wen Chen, Feng Xia, Tieshan Song, and Qiming Ke. Lactylation-driven transcriptional activation of fbxo33 promotes gallbladder cancer metastasis by regulating p53 polyubiquitination. Cell Death & Disease, Feb 2025. URL: https://doi.org/10.1038/s41419-025-07372-y, doi:10.1038/s41419-025-07372-y. This article has 23 citations and is from a peer-reviewed journal.

4. (xiao2023splicingfactorybx1 pages 11-14): Ye Xiao, Guang-Ping Cai, Xu Feng, Yu-Jue Li, Wan-Hui Guo, Qiaoyue Guo, Yan Huang, Tian Su, Changjun Li, Xianghang Luo, Yongjun Zheng, and Mi Yang. Splicing factor ybx1 regulates bone marrow stromal cell fate during aging. The EMBO Journal, Mar 2023. URL: https://doi.org/10.15252/embj.2022111762, doi:10.15252/embj.2022111762. This article has 77 citations.

5. (chen2019fipoqfbxo33acullin‐1‐based pages 9-11): Zhefan Stephen Chen, Azaria Kam Yan Wong, Tat Cheung Cheng, Alex Chun Koon, and Ho Yin Edwin Chan. Fipoq/fbxo33, a cullin‐1‐based ubiquitin ligase complex component modulates ubiquitination and solubility of polyglutamine disease protein. Journal of Neurochemistry, 149:781-798, Jun 2019. URL: https://doi.org/10.1111/jnc.14669, doi:10.1111/jnc.14669. This article has 35 citations and is from a domain leading peer-reviewed journal.

6. (xiao2023splicingfactorybx1 pages 14-15): Ye Xiao, Guang-Ping Cai, Xu Feng, Yu-Jue Li, Wan-Hui Guo, Qiaoyue Guo, Yan Huang, Tian Su, Changjun Li, Xianghang Luo, Yongjun Zheng, and Mi Yang. Splicing factor ybx1 regulates bone marrow stromal cell fate during aging. The EMBO Journal, Mar 2023. URL: https://doi.org/10.15252/embj.2022111762, doi:10.15252/embj.2022111762. This article has 77 citations.

7. (wu2025lactylationdriventranscriptionalactivation pages 1-2): Zhenheng Wu, You Peng, Wen Chen, Feng Xia, Tieshan Song, and Qiming Ke. Lactylation-driven transcriptional activation of fbxo33 promotes gallbladder cancer metastasis by regulating p53 polyubiquitination. Cell Death & Disease, Feb 2025. URL: https://doi.org/10.1038/s41419-025-07372-y, doi:10.1038/s41419-025-07372-y. This article has 23 citations and is from a peer-reviewed journal.

8. (wei2024theubiquitine3 pages 1-1): Qiong Wei, Zichun Liu, Jingfeng Zhu, Wenyan Jiang, Haiqin Xie, Ganzhu Feng, and Keming Wang. The ubiquitin e3 ligase fbxo33 suppresses stem cell-like properties and metastasis in non-small-cell lung cancer by promoting ubiquitination and degradation of myc. Frontiers in bioscience, 29 8:296, Aug 2024. URL: https://doi.org/10.31083/j.fbl2908296, doi:10.31083/j.fbl2908296. This article has 7 citations and is from a peer-reviewed journal.

9. (fischer2023identificationofhypertrophymodulating pages 6-8): Maximillian Fischer, Moritz Jakab, Marc N. Hirt, Tessa R. Werner, Stefan Engelhardt, and Antonio Sarikas. Identification of hypertrophy-modulating cullin-ring ubiquitin ligases in primary cardiomyocytes. Frontiers in Physiology, Mar 2023. URL: https://doi.org/10.3389/fphys.2023.1134339, doi:10.3389/fphys.2023.1134339. This article has 5 citations.

10. (OpenTargets Search: -FBXO33): Open Targets Query (-FBXO33, 5 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

11. (wu2025lactylationdriventranscriptionalactivation pages 13-14): Zhenheng Wu, You Peng, Wen Chen, Feng Xia, Tieshan Song, and Qiming Ke. Lactylation-driven transcriptional activation of fbxo33 promotes gallbladder cancer metastasis by regulating p53 polyubiquitination. Cell Death & Disease, Feb 2025. URL: https://doi.org/10.1038/s41419-025-07372-y, doi:10.1038/s41419-025-07372-y. This article has 23 citations and is from a peer-reviewed journal.

12. (wu2025lactylationdriventranscriptionalactivation pages 4-7): Zhenheng Wu, You Peng, Wen Chen, Feng Xia, Tieshan Song, and Qiming Ke. Lactylation-driven transcriptional activation of fbxo33 promotes gallbladder cancer metastasis by regulating p53 polyubiquitination. Cell Death & Disease, Feb 2025. URL: https://doi.org/10.1038/s41419-025-07372-y, doi:10.1038/s41419-025-07372-y. This article has 23 citations and is from a peer-reviewed journal.

13. (chen2019fipoqfbxo33acullin‐1‐based pages 7-9): Zhefan Stephen Chen, Azaria Kam Yan Wong, Tat Cheung Cheng, Alex Chun Koon, and Ho Yin Edwin Chan. Fipoq/fbxo33, a cullin‐1‐based ubiquitin ligase complex component modulates ubiquitination and solubility of polyglutamine disease protein. Journal of Neurochemistry, 149:781-798, Jun 2019. URL: https://doi.org/10.1111/jnc.14669, doi:10.1111/jnc.14669. This article has 35 citations and is from a domain leading peer-reviewed journal.

14. (chen2019fipoqfbxo33acullin‐1‐based pages 4-6): Zhefan Stephen Chen, Azaria Kam Yan Wong, Tat Cheung Cheng, Alex Chun Koon, and Ho Yin Edwin Chan. Fipoq/fbxo33, a cullin‐1‐based ubiquitin ligase complex component modulates ubiquitination and solubility of polyglutamine disease protein. Journal of Neurochemistry, 149:781-798, Jun 2019. URL: https://doi.org/10.1111/jnc.14669, doi:10.1111/jnc.14669. This article has 35 citations and is from a domain leading peer-reviewed journal.

15. (xiao2022orchestrationofalternative pages 11-14): Ye Xiao, Guang-Ping Cai, Xu Feng, Qi Guo, Yan Huang, Tian Su, Chang-Jun Li, Xiang-Hang Luo, Yong-Jun Zheng, and Mi Yang. Orchestration of alternative splicing regulates bone marrow mesenchymal stem cells fate during aging. BioRxiv, May 2022. URL: https://doi.org/10.1101/2022.05.27.493685, doi:10.1101/2022.05.27.493685. This article has 0 citations.

## Artifacts

- [Edison artifact artifact-00](FBXO33-deep-research-falcon_artifacts/artifact-00.md)

## Citations

1. wu2025lactylationdriventranscriptionalactivation pages 7-10
2. fischer2023identificationofhypertrophymodulating pages 6-8
3. wu2025lactylationdriventranscriptionalactivation pages 1-2
4. wu2025lactylationdriventranscriptionalactivation pages 13-14
5. wu2025lactylationdriventranscriptionalactivation pages 4-7
6. xiao2022orchestrationofalternative pages 11-14
7. https://platform.opentargets.org/target/ENSG00000165355
8. https://doi.org/10.1038/s41419-025-07372-y
9. https://doi.org/10.31083/j.fbl2908296
10. https://doi.org/10.1111/jnc.14669
11. https://doi.org/10.15252/embj.2022111762
12. https://doi.org/10.3389/fphys.2023.1134339
13. https://doi.org/10.1111/jnc.14669,
14. https://doi.org/10.1038/s41419-025-07372-y,
15. https://doi.org/10.15252/embj.2022111762,
16. https://doi.org/10.31083/j.fbl2908296,
17. https://doi.org/10.3389/fphys.2023.1134339,
18. https://doi.org/10.1101/2022.05.27.493685,