CHMP4A Human

What is CHMP4A and what is its genomic location?

CHMP4A (Charged Multivesicular Body Protein 4A) is a human protein encoded by a gene located on chromosome 14. The gene has several reference assemblies including NC_000014.9 (GRCh38.p14 Primary Assembly) and NC_000014.8 (GRCh37.p13 Primary Assembly) . CHMP4A belongs to the ESCRT-III (Endosomal Sorting Complex Required for Transport-III) complex family, which plays crucial roles in membrane budding and scission events during various cellular processes. The protein is characterized by an open reading frame (ORF) of 798 base pairs encoding a functional protein involved in multiple cellular processes .

What are the common synonyms for CHMP4A in scientific literature?

CHMP4A has several alternative designations in scientific literature, reflecting its various functional roles and homologs. These include: C14orf123 (Chromosome 14 Open Reading Frame 123), CHMP4, CHMP4B, HSPC134, SHAX2, SNF7, SNF7-1, VPS32-1, and VPS32A . When searching scientific databases, researchers should use multiple synonym combinations to ensure comprehensive literature coverage, as some studies may use alternative nomenclature depending on the research focus or historical context of the publication.

How does CHMP4A influence breast cancer prognosis?

A prognostic model incorporating CHMP4A expression demonstrated substantial predictive value, with area under the ROC curve (AUC) values of 0.657, 0.622, and 0.624 for 1-year, 3-year, and 5-year survival rates, respectively. Notably, in this model, CHMP4A had the highest weight in the formula compared to other genes (CXCL9, GRHL2, and RPS29), highlighting its pivotal role in determining cancer outcomes .

What is the mechanistic relationship between CHMP4A and CD8+ T-cell infiltration?

CHMP4A promotes CD8+ T-cell infiltration through a well-defined molecular pathway. Mechanistically, CHMP4A downregulates Lysine-specific histone demethylase 1 (LSD1) expression, which leads to accumulation of human endogenous retrovirus (HERV) double-stranded RNA (dsRNA). This accumulation triggers cellular antiviral responses that activate the IFNβ (Interferon beta) pathway and promote the production of downstream chemokines, ultimately attracting CD8+ T lymphocytes to the tumor site .

This relationship has been validated experimentally through multiple approaches:

• Pearson correlation analysis showed positive correlations between CHMP4A expression and infiltrations of T cells, CD8+ T cells, and B lineage cells in breast cancer datasets

• Knockdown of CHMP4A in breast cancer cells decreased CD8+ T-cell migration in ex vivo recruitment assays

• Overexpression of FLAG-CHMP4A increased CD8+ T-cell migration

• Re-expression of CHMP4A in knockdown cells restored CD8+ T-cell migration capabilities

How does CHMP4A interact with the hypoxia response pathway?

CHMP4A plays a significant role in hypoxia response through its interaction with HIF-1α (Hypoxia-Inducible Factor 1-alpha). According to patent information, CHMP4A enhances both the stability and transcriptional activity of HIF-1α . This is particularly relevant to cancer biology as hypoxia is a common feature of solid tumors, and HIF-1α activation can significantly influence tumor progression through regulation of genes involved in angiogenesis, glucose metabolism, and cell survival.

The dual role of CHMP4A in enhancing immune infiltration while also modulating hypoxia response suggests a complex function in the tumor microenvironment. This interaction may represent an important link between hypoxic stress responses and immune regulation in cancer, potentially explaining some of the tumor-suppressive effects observed with CHMP4A expression .

What are optimal methods for modulating CHMP4A expression in experimental models?

Researchers have several validated approaches for manipulating CHMP4A expression in experimental systems:

For CHMP4A Overexpression:

• Plasmid-based expression using vectors like pCMV6-Entry containing the full CHMP4A ORF (798 bp)

• FLAG-tagged CHMP4A constructs for immunoprecipitation and localization studies

• Viral vectors (lentiviral/adenoviral) for stable integration in difficult-to-transfect cells

For CHMP4A Knockdown/Knockout:

• RNA interference through siRNA or shRNA targeting specific CHMP4A sequences

• CRISPR-Cas9 for complete gene knockout or targeted modifications

• Re-expression systems in knockdown cells to validate specificity of observed phenotypes

Validation of successful manipulation should be performed at both mRNA (RT-qPCR) and protein levels (Western blotting), ideally accompanied by functional assays such as T-cell migration tests to confirm biological effects .

How can researchers accurately quantify CHMP4A-mediated immune infiltration?

Quantification of CHMP4A-mediated immune infiltration requires a multi-modal approach:

In Vitro Systems:

• Transwell migration assays using purified CD8+ T cells (>95% purity) and conditioned media from CHMP4A-manipulated cancer cells

• Flow cytometry to characterize migrating T-cell populations

• Chemokine profiling of conditioned media to identify specific factors regulated by CHMP4A

In Vivo Models:

• Immunohistochemistry of tumor sections to quantify CD8+ cell density and distribution

• Flow cytometry of dissociated tumors to enumerate and phenotype infiltrating immune populations

• Correlation analysis between CHMP4A expression levels and immune cell markers

A comprehensive approach combining these methods provides robust evaluation of CHMP4A's impact on tumor immune microenvironment, as demonstrated in published breast cancer studies .

What are the key considerations for developing a prognostic model based on CHMP4A expression?

Development of a CHMP4A-based prognostic model requires careful consideration of several factors:

Data Selection and Preprocessing:

Model Building:

• Incorporate CHMP4A with other relevant genes (such as CXCL9, GRHL2, and RPS29 in breast cancer)

• Validate using metrics like ROC curves (with AUC values reported for 1-, 3-, and 5-year survival)

• Develop nomograms to visualize predicted survival probabilities

Risk Stratification:

• Divide patients into risk groups (high/low) based on median risk scores

• Validate stratification through Kaplan-Meier survival analysis

• Assess model performance across different cancer subtypes and treatment regimens

Published models demonstrate that CHMP4A can be effectively incorporated into prognostic algorithms with significant predictive value for breast cancer outcomes .

How might CHMP4A function be exploited for cancer immunotherapy development?

CHMP4A's role in immune regulation offers several promising avenues for immunotherapy development:

Targeting the CHMP4A/LSD1/IFNβ Axis:

• Development of LSD1 inhibitors that mimic CHMP4A's downstream effects

• Small molecules that enhance CHMP4A expression or activity

• Combination approaches with existing immunotherapies like immune checkpoint inhibitors

Biomarker Applications:

• Using CHMP4A expression as a predictive biomarker for immunotherapy response

• Stratifying patients for clinical trials based on CHMP4A expression levels

• Monitoring changes in CHMP4A expression during treatment as a response indicator

Research suggests that CHMP4A may serve as "a novel target for improving the effectiveness of immunotherapy in patients with BC [breast cancer]," highlighting its potential in precision oncology approaches .

What research gaps remain in understanding CHMP4A's role in human disease?

Despite significant progress, several important research gaps persist:

Functional Diversity:

• Limited understanding of CHMP4A's role beyond breast cancer in other tumor types

• Incomplete characterization of CHMP4A's function in normal tissues and development

• Unclear relationship between CHMP4A's endosomal sorting functions and its immune regulatory roles

Genetic Variation:

• Limited data on CHMP4A genetic variants and their functional/clinical significance

• Unknown impact of somatic mutations affecting CHMP4A in various cancers

• Unexplored pharmacogenomic implications for potential CHMP4A-targeting therapies

Therapeutic Development:

• Lack of specific CHMP4A modulators for preclinical and clinical testing

• Undefined optimal approach for therapeutically targeting the CHMP4A pathway

• Unknown potential adverse effects of CHMP4A manipulation in normal tissues

Addressing these gaps represents an important frontier for future CHMP4A research with significant potential for clinical translation .

How does CHMP4A expression correlate with response to current immunotherapy approaches?

While direct evidence linking CHMP4A expression to immunotherapy response is limited in the search results, several findings suggest potential correlations:

Predictive Indicators:

• CHMP4A promotes CD8+ T-cell infiltration, which is generally associated with better response to immune checkpoint inhibitors

• The CHMP4A-mediated IFNβ pathway activation enhances tumor immunogenicity, potentially improving immunotherapy outcomes

• LSD1 inhibition (which mimics CHMP4A's effect) increases infiltrating CD8+ T cells across multiple cancer types

Research Opportunities:

• Retrospective analysis of CHMP4A expression in immunotherapy clinical trial samples

• Investigation of CHMP4A as a companion biomarker for immunotherapy selection

• Exploration of potential synergistic effects between CHMP4A pathway activation and checkpoint inhibition

These investigations would clarify CHMP4A's role in predicting and enhancing responses to current immunotherapeutic approaches, potentially improving patient selection and outcomes.

What are the most reliable antibodies and detection methods for studying CHMP4A?

While specific antibody recommendations aren't provided in the search results, optimal CHMP4A detection requires careful consideration of:

Antibody Selection Criteria:

• Specificity validation against knockdown/knockout controls

• Demonstrated reactivity in multiple applications (WB, IHC, IF)

• Published validation in peer-reviewed studies

• Appropriate species reactivity for the experimental model

Application-Specific Considerations:

• For Western blotting: Optimal protein extraction methods to preserve CHMP4A integrity

• For immunohistochemistry: Appropriate fixation and antigen retrieval protocols

• For immunofluorescence: Permeabilization optimization for subcellular localization studies

Alternative Detection Approaches:

• TAG-based systems (such as FLAG-CHMP4A mentioned in the literature)

• RNA detection through in situ hybridization or RT-qPCR

• Mass spectrometry for unbiased protein identification and interaction studies

Rigorous validation of detection methods is essential for accurate characterization of CHMP4A expression and function in experimental systems.

What molecular interactions and binding partners of CHMP4A are critical for its function?

Based on the available search results and understanding of CHMP4A biology, several key molecular interactions appear critical:

Immune Regulation Pathway:

• LSD1 (Lysine-specific demethylase 1): CHMP4A downregulates LSD1 expression, affecting downstream HERV dsRNA accumulation and IFNβ signaling

• IFNβ pathway components: Interact with CHMP4A-regulated signaling to promote chemokine production

• Chemokines: Downstream effectors that directly mediate T-cell recruitment

Hypoxia Response:

• HIF-1α: CHMP4A enhances HIF-1α stability and transcriptional activity, affecting hypoxic response

• Potential oxygen-sensing machinery components that integrate with CHMP4A function

ESCRT Machinery:

• Other ESCRT-III components that cooperate with CHMP4A in membrane remodeling

• VPS4: Likely interacts with CHMP4A during membrane scission events

Further protein-protein interaction studies and structural analysis would enhance understanding of these molecular relationships and their functional significance.

What are the emerging technologies that could advance CHMP4A research?

Several cutting-edge technologies hold promise for advancing CHMP4A research:

Single-Cell Approaches:

• Single-cell RNA sequencing to characterize cell-specific CHMP4A expression patterns

• Single-cell proteomics to detect CHMP4A protein levels and modifications

• Spatial transcriptomics to map CHMP4A expression in the tumor microenvironment context

Advanced Imaging:

• Super-resolution microscopy for precise subcellular localization

• Intravital imaging to track CHMP4A dynamics in live tissues

• Multiplexed imaging techniques to simultaneously visualize CHMP4A and immune cells

Functional Genomics:

• CRISPR screens to identify synthetic lethal interactions with CHMP4A

• CRISPR base editing for precise modification of CHMP4A regulatory elements

• Pooled CRISPR libraries targeting CHMP4A pathway components

These emerging technologies could provide unprecedented insights into CHMP4A biology and accelerate therapeutic applications targeting this important protein.