PPIH Human
Description
3.1. Cancer Biomarker Potential
PPIH is overexpressed in multiple cancers and correlates with poor prognosis:
Mechanistic Pathways:
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Cell Cycle Regulation: Enrichment in base excision repair, DNA replication, and spliceosome pathways .
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Immune Modulation: Correlates with tumor-infiltrating immune cells (e.g., macrophages, dendritic cells) and checkpoint proteins (PD-L1, CTLA4) .
3.2. Diagnostic and Prognostic Utility
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Tissue vs. Serum Levels: While tissue PPIH is elevated in tumors (LIHC, COAD, BC), serum levels are paradoxically reduced. Combined with traditional markers (e.g., AFP, CEA), serum PPIH improves diagnostic sensitivity .
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TP53 Mutation Link: Overexpression correlates with TP53 mutations, suggesting synergistic oncogenic effects .
Therapeutic Implications
Product Specs
Q&A
What functional roles does PPIH play in cellular mechanisms, and how are these investigated experimentally?
PPIH acts as a peptidyl-prolyl cis-trans isomerase (PPIase) that catalyzes protein folding by isomerizing proline-containing peptide bonds . Its spliceosomal role involves chaperoning interactions between U4/U5/U6 small nuclear ribonucleoproteins (snRNPs) during pre-mRNA processing . Methodologically, researchers employ:
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Knockdown/knockout models: siRNA or shRNA systems (e.g., MISSION® esiRNA EHU107321) to assess spliceosome dysregulation
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Co-immunoprecipitation: Validating PPIH’s binding partners like PRPF3/4/18 in tri-snRNP complexes
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PPIase activity assays: Fluorescence polarization using synthetic tetrapeptide substrates (e.g., Suc-AAPF-pNA)
Recent TCGA data reveals PPIH overexpression in cholangiocarcinoma (CHOL), correlating with TP53 mutations (Spearman’s ρ=0.38, p=0.017) .
How is PPIH validated as a diagnostic biomarker for cholangiocarcinoma?
The validation pipeline involves:
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Transcriptomic screening: Analyzing GEO datasets (GSE32958/GSE76311) showing PPIH mRNA upregulation (log2FC=3.1, FDR<0.001)
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Immunohistochemical confirmation: Anti-PPIH antibodies (HPA059019) demonstrate 89% sensitivity in CHOL tissues vs. adjacent normal
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ROC analysis: AUC=0.963 (95% CI:0.936–0.984) outperforms CEACAM5 (AUC=0.811) and THBS2 (AUC=0.803)
| Biomarker | Sensitivity (%) | Specificity (%) | AUC |
|---|---|---|---|
| PPIH | 92.3 | 88.7 | 0.963 |
| CEACAM5 | 76.1 | 81.9 | 0.811 |
| THBS2 | 68.4 | 77.2 | 0.803 |
What standard experimental models are used to study PPIH’s oncogenic mechanisms?
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In vitro:
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In vivo:
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Omics integration:
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CRISPR-Cas9 screens paired with RNA-seq to identify synthetic lethal partners
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How does PPIH influence immune infiltration in cholangiocarcinoma, and what experimental strategies quantify this?
PPIH correlates with CD8+ T-cell exhaustion (PD-1+/TIM-3+ subset increase from 12% to 38% in high-PPIH tumors) . Investigators use:
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CIBERSORTx deconvolution: Estimating immune cell fractions from bulk RNA-seq (PPIHhigh vs. PPIHlow):
Immune Cell Type PPIHhigh (%) PPIHlow (%) p-value M2 Macrophages 22.1 14.3 0.008 Tregs 9.8 5.2 0.013 CD8+ T-cells 6.4 11.7 0.021 -
Multiplex IHC: 7-color panels quantifying spatial immune-PPIH interactions
What methodologies resolve contradictions in PPIH-related clinical literature (e.g., opposing therapeutic findings)?
The ACL Anthology framework applies ontology-driven contradiction detection :
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SNOMED CT ontology mapping: Aligning PPIH-associated terms (e.g., "PPIH overexpression", "spliceosome inhibition")
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Distant supervision: Training BERT variants on 22M PubMed abstracts to flag contradictory pairs (F1=0.72 vs. 0.65 baseline)
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Hard contradiction analysis: Removing negation artifacts (e.g., "PPIH does not correlate" → focus on outcome conflicts)
Example contradiction resolution:
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Study A: "PPIH knockdown reduces tumor growth in xenografts"
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Study B: "PPIH inhibition accelerates metastasis in PDX models"
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Resolution: Contextualize via TP53 status—PPIH promotes growth in TP53WT but enables EMT in TP53mut
How are multi-omics approaches leveraged to dissect PPIH’s role in spliceosome-immune crosstalk?
Integrative analysis pipelines include:
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Phosphoproteomics: Identifying PPIH-dependent splicing factors (e.g., SRSF2 phosphorylation at Ser206)
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ATAC-seq: Revealing chromatin accessibility changes at immune loci (e.g., IFN-γ promoter) post-PPIH knockdown
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Single-cell RNA-seq: Subclustering CHOL ecosystems into PPIHhigh malignant (EpCAM+/CK19+) and PPIHlow stromal niches
Critical validation step: Spatial transcriptomics (Visium HD) mapping PPIH expression gradients to immune exclusion zones.
What experimental artifacts confound PPIH activity measurements, and how are they mitigated?
Common pitfalls:
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PPIase assay interference: Thiol-containing buffers inactivate PPIH; use 50 mM Tris-HCl (pH 8.0)/0.1% CHAPS instead
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Antibody cross-reactivity: Validate HPA059019 with Ppih−/− murine liver lysates
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Spliceosome lability: Perform co-IP under 150 mM KCl to preserve snRNP integrity
How do researchers validate PPIH’s spliceosome-independent roles in metabolic reprogramming?
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Cycloheximide chase assays: Measure HIF-1α half-life (PPIH knockdown increases degradation t1/2 from 12→28 mins)
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Seahorse metabolic profiling: PPIH−/− cells show 34% reduction in OCR (p=0.007)
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13C-glucose tracing: Reduced citrate m+2 labeling in PPIH-deficient mitochondria
What translational challenges hinder PPIH-targeted therapy development?
Key bottlenecks:
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On-target toxicity: Global PPIH inhibition disrupts constitutive splicing (viability <40% at 10 nM inhibitor)
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Biomarker stratification: PDX models require TP53 mutation + PPIHhigh status for response (OR=4.2 vs. wild-type)
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Drug delivery: Nanoparticle encapsulation (PLGA-PEG) improves tumor:plasma ratio from 0.3→2.7
Product Science Overview
Cyclophilin-H is a specific component of the human spliceosome, a complex responsible for the removal of introns from pre-mRNA. It plays a crucial role in the splicing of pre-mRNA by interacting with other spliceosomal proteins and RNA . The enzyme’s activity is essential for the proper folding and function of proteins, making it a vital player in cellular processes.
Recombinant human Cyclophilin-H is produced using recombinant DNA technology, which involves inserting the gene encoding Cyclophilin-H into a suitable expression system, such as bacteria or yeast. This allows for the production of large quantities of the protein for research and therapeutic purposes .
Cyclophilin-H has been studied extensively for its role in various cellular processes and its potential therapeutic applications. Some key areas of research and application include:
- Protein Folding: Cyclophilin-H assists in the proper folding of proteins, which is crucial for their function. Misfolded proteins can lead to various diseases, including neurodegenerative disorders.
- Spliceosome Function: As a component of the spliceosome, Cyclophilin-H is essential for the accurate splicing of pre-mRNA, a critical step in gene expression.
- Drug Target: Cyclophilins, including Cyclophilin-H, are targets for immunosuppressive drugs like cyclosporin A, which is used to prevent organ transplant rejection .
- Disease Research: Understanding the function and regulation of Cyclophilin-H can provide insights into diseases related to protein misfolding and splicing defects.
