ATP1B3 Human

What is ATP1B3 and what are its fundamental characteristics?

ATP1B3 is the beta-3 subunit of Na+/K+-ATPase, encoded by the ATP1B3 gene in humans. It belongs to the family of Na+/K+ and H+/K+ ATPases beta chain proteins, which function as plasma membrane pumps with numerous physiological roles . The gene is mapped to chromosome 3q23, with a pseudogene located on chromosome 2 .

The protein consists of 279 amino acids with a single transmembrane domain and functions as the non-catalytic component of the active enzyme . The C-terminal portion of ATP1B3 folds into an immunoglobulin-like domain, which is critical for its structural and functional properties .

Key characteristics of ATP1B3:

What are the primary physiological functions of ATP1B3?

ATP1B3 serves as a key component of the Na+/K+-ATPase complex, which is essential for establishing and maintaining electrochemical gradients of Na+ and K+ ions across the plasma membrane . This function is critical for:

• Osmoregulation in various cell types

• Sodium-coupled transport of organic and inorganic molecules

• Maintaining electrical excitability of nerve and muscle cells

Additionally, ATP1B3 has been implicated in immune function, with research demonstrating its ability to up-regulate lymphocyte activity and promote the production of several cytokines including IFN-γ, IL-2, IL-4, and IL-10 . This suggests ATP1B3 may function beyond its classical role in ion transport to influence immune responses.

Recent studies also indicate ATP1B3 acts as a co-factor that accelerates BST-2 degradation and reduces BST-2-mediated restriction of HIV-1 production and NF-κB activation, suggesting a role in viral infection dynamics .

How is ATP1B3 expression regulated in normal human tissues?

ATP1B3 shows differential expression patterns across human tissues. While the search results don't provide comprehensive details on all tissues, they reveal important patterns in specific tissues such as the cochlea, where ATP1B3 transcript distribution has been mapped .

In the cochlea, ATP1B3 expression appears to be cell-type specific. Type I spiral ganglion cells express ATP1B1 gene transcripts at levels exceeding those in marginal cells by approximately 20 times and type II fibrocytes by nine times . Interestingly, axons have been found to lack ATP1B3 gene transcripts, while the NKAβ1 protein is richly expressed along the axonal plasma membrane in certain neuronal populations .

The regulation of ATP1B3 expression appears to be context-dependent, with evidence of altered expression in various pathological states, including cancer. This suggests complex transcriptional and post-transcriptional regulatory mechanisms that warrant further investigation.

What role does ATP1B3 play in cancer progression and immune infiltration?

ATP1B3 has emerged as a significant factor in cancer biology, with evidence supporting its oncogenic role in multiple cancer types:

ATP1B3 expression correlates positively with markers of several immune cell populations in the tumor microenvironment, including:

• CD8+ T cells

• General T cells

• M1 Macrophages

• B cells

• Tumor-associated macrophages (TAMs)

This correlation with immune infiltration has been validated at both mRNA and protein levels using proteomics datasets .

In gastric cancer, ATP1B3 overexpression promotes multiple aspects of cancer progression, including:

• Tumor cell proliferation

• Invasion capacity

• Resistance to apoptosis

• Cell-cycle dysregulation

Mechanistically, ATP1B3 appears to promote malignant progression in gastric cancer through activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway .

In glioma, ATP1B3 may influence tumor cell proliferation and migration through modulation of the MAPK and NF-κB signaling pathways . Knockdown experiments in glioma cell lines (U87MG and U251MG) have demonstrated that reducing ATP1B3 expression impacts the invasive and proliferative capacities of these cells .

What methodological approaches are most effective for studying ATP1B3 function in experimental models?

Based on the search results, several methodological approaches have proven effective for investigating ATP1B3 function:

• Gene Expression Analysis:

  • Utilization of public databases (TCGA, ICGC, GEO, CGGA) to analyze differential expression across tissue types and disease states

  • RT-qPCR for validation of expression levels in cell lines and tissue samples

• Functional Knockdown Studies:

  • siRNA interference approaches to reduce ATP1B3 expression in cell lines

  • Assessment of knockdown efficiency using Western Blotting and RT-qPCR

• Phenotypic Assays:

  • CCK-8 assay for cell proliferation analysis following ATP1B3 knockdown

  • Transwell assay for migration and invasion assessment

  • Apoptosis assays to determine the impact on cell survival

• Protein-Protein Interaction Studies:

  • Immunoprecipitation to determine direct protein interactions (e.g., ATP1B3 interaction with PPP1CA in glioma)

  • Immunofluorescence for analyzing protein co-distribution in cells

• Signaling Pathway Analysis:

  • Western Blotting to assess changes in signaling pathway components following ATP1B3 manipulation

  • Analysis of phosphorylation status of key signaling molecules in the MAPK pathway (p-Raf1, p-MEK 1/2, p-ERK 1/2) and NF-κB pathway (p-IκBα, p-P65)

  • Investigation of downstream effectors such as Cyclin D1 and VEGFA

• Integrative Approaches:

  • Combined transcriptomic and proteomic analyses to validate findings across multiple levels of biological organization

  • Correlation analyses between ATP1B3 expression and clinical parameters

How do ATP1B3 expression patterns correlate with patient outcomes in different cancer types?

ATP1B3 expression demonstrates significant correlations with patient outcomes across multiple cancer types, though the prognostic implications appear to be cancer-specific:

In hepatocellular carcinoma (HCC):

In gliomas:

• Database analysis reveals a negative correlation between ATP1B3 expression and patient outcomes

• Higher expression appears to correlate with more aggressive disease

In gastric cancer:

• Overexpression of ATP1B3 is associated with adverse clinical outcomes

• The protein promotes tumor cell proliferation, invasion, anti-apoptosis mechanisms, and cell-cycle dysregulation

• These effects appear to be mediated through the PI3K/AKT signaling pathway

The studies collectively suggest that ATP1B3 overexpression is generally associated with poorer prognosis across multiple cancer types, making it a potential biomarker for disease progression and treatment response.

What technical challenges exist in ATP1B3 research and how can they be addressed?

Several technical challenges exist in ATP1B3 research that researchers should be aware of:

• Distinguishing between ATP1B family members:
  The ATP1B family includes multiple members (ATP1B1, ATP1B2, ATP1B3, ATP1B4) with partially overlapping functions. Designing highly specific primers, antibodies, and siRNAs is crucial to avoid cross-reactivity. Validation using multiple methods (qPCR, Western blot, immunostaining) is recommended to ensure specificity.

• Subcellular localization assessment:
  As a membrane protein with a single transmembrane domain, properly preserving membrane structures during sample preparation is essential. For immunofluorescence studies, appropriate permeabilization protocols that maintain membrane integrity while allowing antibody access are necessary .

• Functional redundancy:
  Other Na+/K+-ATPase β subunits may compensate for ATP1B3 knockdown. Consider using combinatorial knockdown approaches or rescue experiments to address this issue.

• Protein-protein interaction studies:
  The interaction partners of ATP1B3 (such as PPP1CA in glioma) may be tissue or context-specific . Use proximity ligation assays or FRET in addition to traditional co-immunoprecipitation to validate interactions in their native cellular context.

• Translating in vitro findings to in vivo contexts:
  Establish appropriate animal models that recapitulate the physiological or pathological context being studied. Consider conditional knockout/knockin models to avoid developmental effects of ATP1B3 manipulation.

What experimental controls are essential when studying ATP1B3 in cancer models?

When investigating ATP1B3 in cancer models, several essential controls should be implemented:

• Expression controls:

  • Compare ATP1B3 expression between matched tumor and adjacent non-tumor tissues from the same patients

  • Include normal cell lines of the same tissue origin alongside cancer cell lines

  • Consider multiple cancer cell lines to account for heterogeneity

• Knockdown/overexpression controls:

  • Use multiple siRNA sequences targeting different regions of ATP1B3 to rule out off-target effects

  • Include scrambled siRNA controls with similar GC content

  • For overexpression studies, use empty vector controls and consider inducible systems to control expression levels

• Functional assay controls:

  • Perform rescue experiments by re-expressing siRNA-resistant ATP1B3 constructs

  • Include positive controls for cell proliferation, migration, and apoptosis assays

  • Time-course analyses to determine the temporal dynamics of ATP1B3-mediated effects

• Signaling pathway controls:

  • Use specific pathway inhibitors to validate the involvement of proposed downstream pathways (e.g., PI3K/AKT, MAPK, NF-κB inhibitors)

  • Monitor multiple components of each pathway to establish causality

  • Include positive controls for pathway activation

• Clinical correlation controls:

  • Stratify patients by relevant clinical parameters (disease stage, treatment history)

  • Account for potential confounding variables in multivariate analyses

  • Validate findings across independent patient cohorts

How can researchers effectively measure ATP1B3 function in relation to immune modulation?

Given the emerging role of ATP1B3 in immune modulation, particularly in cancer contexts, several methodological approaches can effectively assess its immunomodulatory functions:

• Immune cell infiltration analysis:

  • Use immunohistochemistry or multiplexed immunofluorescence to quantify immune cell populations in tissue sections

  • Analyze spatial relationships between ATP1B3-expressing cells and immune infiltrates

  • Apply computational approaches to quantify immune cell distributions

• Cytokine profiling:

  • Measure secreted cytokines using multiplexed ELISA or cytometric bead arrays following ATP1B3 manipulation

  • Assess changes in cytokine receptor expression on target cells

  • Monitor changes in IFN-γ, IL-2, IL-4, and IL-10, which have been specifically linked to ATP1B3 function

• Co-culture systems:

  • Establish co-culture models of cancer cells and immune cells (T cells, macrophages, B cells)

  • Manipulate ATP1B3 expression in cancer cells and assess changes in immune cell activation, proliferation, and effector functions

  • Use transwell systems to distinguish between contact-dependent and secreted factor-mediated effects

• Single-cell analysis:

  • Apply single-cell RNA sequencing to characterize heterogeneity in ATP1B3 expression and its correlation with immune phenotypes

  • Use CyTOF or spectral flow cytometry to simultaneously assess multiple immune parameters

  • Integrate these data with spatial information using techniques like imaging mass cytometry

• In vivo immune monitoring:

  • Utilize syngeneic mouse models with ATP1B3 manipulation in cancer cells

  • Monitor changes in tumor-infiltrating lymphocytes, myeloid populations, and systemic immune parameters

  • Assess response to immunotherapies in the context of ATP1B3 modulation

What are the most promising therapeutic strategies targeting ATP1B3 in cancer?

Several promising therapeutic approaches targeting ATP1B3 in cancer warrant further investigation:

• RNA interference-based therapies:

  • Development of siRNA or shRNA delivery systems specifically targeting ATP1B3 in cancer cells

  • Exploration of lipid nanoparticles or exosome-based delivery methods to improve targeting

  • Combination with existing chemotherapies to enhance efficacy

• Small molecule inhibitors:

  • Design of specific inhibitors targeting the interaction between ATP1B3 and alpha subunits

  • Development of compounds that disrupt ATP1B3's interactions with downstream signaling partners

  • Repurposing of existing Na+/K+-ATPase inhibitors with optimized specificity for ATP1B3-containing complexes

• Immunotherapeutic approaches:

  • Given ATP1B3's correlation with immune infiltration, exploration of combination therapies with immune checkpoint inhibitors

  • Development of strategies to modulate ATP1B3's impact on the tumor immune microenvironment

  • Investigations into ATP1B3's role in resistance to existing immunotherapies

• Targeting downstream pathways:

  • Combined inhibition of ATP1B3 and key components of the PI3K/AKT, MAPK, or NF-κB pathways

  • Identification of synthetic lethal interactions with ATP1B3 overexpression

  • Exploration of temporal dynamics in pathway inhibition for optimized therapeutic effects

• Biomarker development:

  • Validation of ATP1B3 as a prognostic biomarker across multiple cancer types

  • Investigation of ATP1B3 as a predictive biomarker for response to specific therapies

  • Development of diagnostic assays for clinical implementation

What unexplored aspects of ATP1B3 biology warrant further investigation?

Despite significant progress in understanding ATP1B3 function, several unexplored aspects merit further investigation:

• Post-translational modifications:
  The regulation of ATP1B3 through phosphorylation, glycosylation, or other modifications remains poorly characterized. Investigations into how these modifications affect ATP1B3 function, localization, and interactions could reveal new regulatory mechanisms.

• Non-canonical functions:
  Beyond its role in Na+/K+-ATPase activity, ATP1B3 may have additional functions, particularly in immune modulation and viral infection resistance . Systematic interactome studies could uncover novel binding partners and functional roles.

• Tissue-specific roles:
  While ATP1B3's functions have been studied in certain contexts (cancer, cochlea), its tissue-specific roles across different organ systems remain largely unexplored . Comparative studies across tissues could reveal specialized functions.

• Developmental biology:
  The role of ATP1B3 during embryonic development and in stem cell biology has received limited attention. Studies on ATP1B3's contribution to developmental processes and tissue differentiation could provide valuable insights.

• Extracellular vesicle involvement:
  Given its membrane localization, ATP1B3 may be incorporated into extracellular vesicles, potentially mediating intercellular communication. Investigating ATP1B3's presence and function in exosomes could reveal novel mechanisms of action.

• Metabolic influences:
  The relationship between ATP1B3 and cellular metabolism, particularly in the context of cancer's metabolic reprogramming, remains to be elucidated. Studies on how ATP1B3 affects or responds to metabolic states could uncover new therapeutic opportunities.

How might ATP1B3 research intersect with emerging technologies in biomedical science?

ATP1B3 research stands to benefit significantly from integration with emerging technologies:

• CRISPR-based approaches:

  • Application of CRISPR screening to identify synthetic lethal interactions with ATP1B3

  • Development of CRISPR-based ATP1B3 regulators for precise temporal control

  • Use of base editing or prime editing for introducing specific ATP1B3 mutations

• Spatial transcriptomics and proteomics:

  • Mapping ATP1B3 expression patterns with cellular resolution in complex tissues

  • Correlating ATP1B3 with other markers to define cellular neighborhoods

  • Investigating the spatial relationships between ATP1B3-expressing cells and immune infiltrates

• Artificial intelligence and machine learning:

  • Development of predictive models for ATP1B3-associated patient outcomes

  • Integration of multi-omics data to uncover ATP1B3 regulatory networks

  • Virtual screening for ATP1B3-targeting compounds

• Organoid technologies:

  • Establishment of patient-derived organoids to study ATP1B3 in more physiologically relevant systems

  • Development of co-culture organoid models incorporating immune components

  • High-throughput drug screening in ATP1B3-manipulated organoids

• Single-molecule imaging:

  • Visualization of ATP1B3 dynamics in living cells using techniques like PALM/STORM

  • Analysis of ATP1B3 clustering and interaction with other membrane proteins

  • Real-time monitoring of ATP1B3's role in membrane organization

• Nanobody and aptamer development:

  • Creation of highly specific ATP1B3-targeting nanobodies for functional studies

  • Development of aptamer-based sensors for monitoring ATP1B3 expression in real-time

  • Targeted delivery of therapeutic agents to ATP1B3-overexpressing cells