Recombinant Bovine Transmembrane protein 158 (TMEM158)

What is TMEM158 and what are its primary biological functions?

TMEM158 (Transmembrane protein 158), also known as RIS1 (Ras-induced senescence protein 1), is a transmembrane protein that functions as a receptor for brain injury-derived neurotrophic peptide (BINP), a synthetic 13-mer peptide . It plays critical roles in various cellular processes including:

• Cell growth, differentiation, and apoptosis regulation

• Signal transduction across cell membranes

• Cellular senescence pathways (particularly Ras-induced senescence)

• Epithelial-mesenchymal transition (EMT) in various tissues

Research has shown that TMEM158 expression is dysregulated in several pathological conditions, particularly in various cancers, suggesting its importance in cellular homeostasis .

How does bovine TMEM158 differ from human TMEM158?

Bovine TMEM158 shares significant sequence homology with human TMEM158, but with notable differences:

While the proteins share functional domains, researchers should note these differences when designing cross-species experiments or when using bovine TMEM158 as a model for human applications .

What expression systems are commonly used to produce recombinant bovine TMEM158?

Several expression systems have been successfully employed to produce recombinant bovine TMEM158, each with distinct advantages:

For most basic research applications, E. coli-expressed TMEM158 with appropriate tags (commonly His-tag) provides sufficient purity (typically >85-90% by SDS-PAGE) and yield . For studies requiring native glycosylation patterns, mammalian expression systems are recommended despite lower yields .

What are the optimal buffer conditions for maintaining recombinant bovine TMEM158 stability?

Maintaining TMEM158 stability requires careful attention to buffer composition:

For reconstitution of lyophilized TMEM158, it is recommended to briefly centrifuge the vial before opening to bring contents to the bottom, then reconstitute in deionized sterile water to a concentration of 0.1-1.0 mg/mL. For working solutions, aliquot and store at 4°C for up to one week to avoid repeated freeze-thaw cycles that significantly reduce protein activity .

What purification strategies yield the highest purity recombinant bovine TMEM158?

A multi-step purification approach yields the highest purity TMEM158 preparations:

• Initial capture: Affinity chromatography using His-tag (for His-tagged TMEM158) with Ni-NTA resins typically achieves 75-80% purity

• Intermediate purification: Ion exchange chromatography (typically anion exchange) to separate based on charge differences

• Polishing step: Size exclusion chromatography to remove aggregates and achieve >90-95% purity

Critical purification parameters:

• Maintain 0.1% detergent (typically non-ionic) throughout purification to prevent aggregation

• Include protease inhibitors in initial lysis buffers to prevent degradation

• Perform quality control using SDS-PAGE and Western blotting with anti-TMEM158 antibodies to confirm identity and purity

How can researchers verify the functionality of purified recombinant bovine TMEM158?

Functional verification of purified TMEM158 should include multiple complementary approaches:

• Structural integrity assessment:

  • Circular dichroism (CD) spectroscopy to confirm secondary structure

  • Thermal shift assays to evaluate protein stability

  • Limited proteolysis to verify proper folding

• Binding assays:

  • Surface plasmon resonance (SPR) with known interaction partners

  • ELISA-based binding assays with BINP peptide (as TMEM158 functions as a BINP receptor)

  • Co-immunoprecipitation with potential binding partners identified in literature

• Functional assays:

  • Cell-based migration and invasion assays (if overexpressing in cell models)

  • Assessment of downstream signaling activation (e.g., TGF-β pathway components)

  • Evaluation of EMT marker changes in cells expressing recombinant TMEM158

How does TMEM158 regulate the epithelial-mesenchymal transition (EMT) process in cancer progression?

TMEM158 has been identified as a key regulator of EMT across multiple cancer types, operating through several mechanisms:

• Direct modulation of EMT markers:

  • Upregulates mesenchymal markers (N-cadherin, vimentin)

  • Downregulates epithelial markers (E-cadherin)

  • Activates EMT transcription factors (ZEB1, SNAIL, Twist1)

• Signaling pathway activation:

  • TGF-β pathway: TMEM158 activates both canonical (Smad-dependent) and non-canonical (ERK1/2-dependent) TGF-β signaling

  • MAPK pathway: Studies show TMEM158 affects MAPK pathway activation, contributing to EMT progression

  • STAT3 pathway: In glioma, TMEM158-driven progression involves STAT3 activation

• Morphological changes:

  • TMEM158 overexpression leads to fibroblast-like cellular features

  • Knockdown results in cells becoming shorter and rounder with epithelial-like features

Experimental data from triple-negative breast cancer studies demonstrate that TMEM158 knockdown reverses the EMT phenotype, while overexpression promotes it. Western blotting analysis reveals significant changes in EMT markers following TMEM158 manipulation, establishing its mechanistic role in cancer progression .

Recent research, particularly in lung cancer models, has established an important relationship between hypoxia and TMEM158:

• Transcriptional regulation:

  • Sequence analysis has identified putative hypoxia-responsive element (HRE) sites in the TMEM158 promoter region

  • Under hypoxic conditions, TMEM158 expression is induced in a HIF-1α-dependent manner

  • Knockdown of HIF-1α reduces hypoxia-induced TMEM158 upregulation

• Functional consequences in hypoxic microenvironments:

  • Enhanced EMT progression in hypoxic tumor regions

  • Increased migration capacity of cancer cells expressing high levels of TMEM158

  • Potential resistance to therapy through hypoxia-induced TMEM158 expression

• Clinical correlations:

  • In advanced-stage tumors (which often contain hypoxic regions), TMEM158 expression is typically elevated

  • Gene set enrichment analysis (GSEA) has confirmed associations between TMEM158 expression and hypoxia-related gene signatures

These findings suggest that targeting TMEM158 may be particularly effective in hypoxic tumors, representing a potential therapeutic approach for tumors with significant hypoxic regions .

What controls should be included when studying TMEM158 function using RNA interference or overexpression models?

Proper experimental design for TMEM158 functional studies requires rigorous controls:

For RNA interference (RNAi) studies:

• Negative controls:

  • Non-targeting siRNA with similar GC content

  • Empty vector control for shRNA studies

  • Confirmation with at least two independent siRNA sequences targeting different regions of TMEM158 mRNA (as demonstrated in studies with siRNA1 and siRNA2)

• Knockdown validation:

  • Western blot confirmation of protein reduction (>70% reduction recommended)

  • qRT-PCR confirmation of mRNA reduction

  • Rescue experiments by re-expressing siRNA-resistant TMEM158 to confirm specificity

For overexpression studies:

• Vector controls:

  • Empty vector transfection as baseline

  • Expression of unrelated transmembrane protein of similar size

• Expression validation:

  • Western blot confirmation of successful expression

  • Immunofluorescence to confirm proper localization to the membrane

  • Functional saturation testing to determine optimal expression levels

• Time course measurements:

  • Analysis at multiple time points post-transfection (24h, 48h, 72h)

  • Assessment of potential compensation mechanisms

What cell-based assays most effectively measure TMEM158 functional effects?

Based on established research, the following complementary assays provide comprehensive assessment of TMEM158 function:

• Proliferation assays:

  • CCK-8 assay (preferred for sensitivity)

  • Colony formation assay (for long-term effects)

  • Cell cycle analysis by flow cytometry (particularly G1-phase effects)

• Migration and invasion assays:

  • Wound healing assay (for 2D migration)

  • Transwell migration assay (for directed migration)

  • Matrigel invasion assay (for invasive capacity)

  Researchers have documented significant differences in migration rates between TMEM158-knockdown and control cells at 24h and 48h time points

• EMT assessment:

  • Morphological analysis (fibroblast-like vs. epithelial-like features)

  • Western blotting for EMT markers (E-cadherin, N-cadherin, vimentin)

  • Immunofluorescence for EMT transcription factors (ZEB1, SNAIL, Twist1)

• Signaling pathway analysis:

  • Western blotting for phosphorylated ERK1/2 and Smad2/3

  • Pathway inhibitor studies (e.g., ERK inhibitor PD98059)

  • Reporter assays for TGF-β pathway activation

How can researchers design in vivo experiments to study TMEM158 function in cancer models?

Effective in vivo experimental design for TMEM158 studies requires careful consideration of multiple factors:

• Animal model selection:

  • Xenograft models using stable TMEM158-knockdown or overexpressing cell lines

  • Patient-derived xenografts to maintain tumor heterogeneity

  • Genetically engineered mouse models (if available)

  Established protocols have used subcutaneous injection of TMEM158-silenced cells in athymic nude mice, following tumor growth for 45 days

• Intervention timepoints:

  • Preventive model: Modify TMEM158 expression before tumor establishment

  • Therapeutic model: Modify TMEM158 expression in established tumors

  • Consideration of tumor stage progression timelines

• Comprehensive endpoints:

  • Tumor volume measurements (calculated as length × width²/2)

  • Tumor weight at endpoint

  • Immunohistochemical analysis of tumor sections for:

    • TMEM158 expression validation

    • Proliferation markers (Ki-67)

    • EMT markers

    • Signaling pathway activation

  • Metastatic burden assessment in relevant organs

• Experimental variables to control:

  • Mouse strain, age, sex, and housing conditions

  • Sample size calculations based on expected effect sizes

  • Blinded assessment of tumor measurements and histopathology

  • Include both male and female mice to assess sex-specific differences

How does TMEM158 expression correlate with clinical outcomes across different cancer types?

Systematic analysis of clinical datasets reveals consistent correlation patterns between TMEM158 expression and patient outcomes:

These correlations highlight the context-dependent nature of TMEM158's role in cancer progression and suggest potential value as a prognostic biomarker .

What methodological approaches should be used to study TMEM158 in patient-derived samples?

Robust analysis of TMEM158 in clinical samples requires multi-modal approaches:

• Tissue processing and preservation:

  • Flash freezing for RNA/protein extraction

  • Formalin fixation and paraffin embedding for immunohistochemistry

  • Collection of matched normal adjacent tissue as essential controls

  • Consideration of tumor heterogeneity through multiple sampling sites

• Expression analysis methods:

  • Immunohistochemistry (IHC):

    • Validated antibodies with proper controls

    • Quantitative scoring systems (H-score or Allred)

    • Comparison between tumor core and invasive edge

  • RNA expression:

    • qRT-PCR for targeted analysis

    • RNA-sequencing for comprehensive profiling

    • In situ hybridization for spatial context

  • Protein quantification:

    • Western blotting from tissue lysates

    • Reverse phase protein arrays

    • Mass spectrometry for unbiased profiling

• Clinical data integration:

  • Comprehensive collection of clinicopathological variables

  • Long-term follow-up data

  • Treatment response information

  • Integration with molecular subtyping data

How can TMEM158 research findings be translated toward potential therapeutic applications?

Translating TMEM158 research into therapeutic strategies requires consideration of several approaches:

• Target validation strategies:

  • Genetic approaches:

    • CRISPR/Cas9-mediated knockout in preclinical models

    • Inducible knockdown systems to assess temporal requirements

    • Rescue experiments to confirm specificity

  • Pharmacological approaches:

    • Development of small molecule inhibitors targeting TMEM158

    • Monoclonal antibodies against extracellular domains

    • Peptide-based antagonists mimicking interaction interfaces

• Context-specific considerations:

  • Cancer-type specificity:

    • Targeting TMEM158 appears promising in glioblastoma, TNBC, pancreatic, and lung cancers where it's upregulated

    • Caution needed in prostate cancer where downregulation correlates with disease progression

  • Combination approaches:

    • With TGF-β pathway inhibitors (given mechanistic connections)

    • With hypoxia-targeting agents in hypoxic tumors

    • With standard chemotherapies as sensitizing strategy

• Biomarker development for patient selection:

  • TMEM158 expression as predictive biomarker for response

  • EMT status as complementary biomarker

  • Development of companion diagnostics

What are the challenges in detecting membrane-bound TMEM158 in experimental systems?

Detection of transmembrane proteins like TMEM158 presents unique technical challenges:

• Antibody selection and validation:

  • Many commercial antibodies target internal epitopes requiring permeabilization

  • Validation across multiple techniques (Western blot, IHC, flow cytometry)

  • Confirmation with knockout/knockdown controls

  • Need for non-denaturing conditions to preserve conformational epitopes

• Sample preparation considerations:

  • Membrane protein extraction requires specialized buffers containing:

    • Non-ionic detergents (0.5-1% Triton X-100 or NP-40)

    • Protease inhibitor cocktails

    • Phosphatase inhibitors when studying phosphorylation status

  • Avoiding excessive heat during processing (maintain 4°C when possible)

  • Gentle mechanical disruption methods

• Microscopy techniques:

  • Surface versus total protein distinction using non-permeabilized versus permeabilized conditions

  • Super-resolution microscopy for detailed localization

  • Live-cell imaging with fluorescently-tagged TMEM158 constructs

How can researchers analyze TMEM158-protein interactions to elucidate its signaling mechanisms?

Understanding TMEM158's interaction network requires sophisticated approaches:

• Immunoprecipitation-based methods:

  • Co-immunoprecipitation with tagged TMEM158

  • Proximity-dependent biotinylation (BioID or TurboID)

  • Cross-linking mass spectrometry for transient interactions

  • RIME (Rapid Immunoprecipitation Mass spectrometry of Endogenous proteins)

• Live-cell interaction methods:

  • FRET (Förster Resonance Energy Transfer) for direct interactions

  • BRET (Bioluminescence Resonance Energy Transfer)

  • Split-protein complementation assays

  • Optogenetic approaches for temporal control

• Membrane-specific considerations:

  • Detergent selection critical for maintaining interactions

  • Lipid raft analysis for compartment-specific interactions

  • Reconstitution in artificial membrane systems

  • Consideration of post-translational modifications affecting interactions

Published studies have identified interactions with components of the TGF-β, MAPK, and STAT3 pathways, providing direction for further interaction studies .

What advanced genomic approaches can help understand TMEM158 regulation in different tissues?

Modern genomic technologies offer powerful insights into TMEM158 regulation:

• Transcriptional regulation analysis:

  • ChIP-seq for identifying transcription factor binding:

    • Focus on hypoxia-inducible factors (HIFs) given hypoxia connection

    • Analysis of androgen receptor binding in prostate tissues

  • ATAC-seq for chromatin accessibility mapping

  • CUT&RUN or CUT&Tag for higher resolution factor binding

  • HiChIP for enhancer-promoter interactions

• Epigenetic regulation:

  • DNA methylation analysis of the TMEM158 promoter

  • Histone modification mapping (H3K27ac, H3K4me3, H3K27me3)

  • Single-cell multi-omics for heterogeneity assessment

  • Chromosome conformation capture to identify distant regulatory elements

• Post-transcriptional regulation:

  • miRNA binding site analysis (miRNA-seq combined with target prediction)

  • RNA-binding protein immunoprecipitation (RIP-seq)

  • mRNA stability assessment with actinomycin D chase experiments

  • Alternative splicing analysis via RNA-seq

Research has revealed context-specific regulation, such as androgen-dependent downregulation in prostate cancer cells and hypoxia-induced upregulation in lung cancer models, highlighting the complexity of TMEM158 regulation across tissues .

What emerging technologies could advance our understanding of TMEM158 function?

Several cutting-edge technologies show promise for deepening TMEM158 research:

• Single-cell technologies:

  • Single-cell RNA-seq to capture heterogeneity in TMEM158 expression

  • Single-cell proteomics for protein-level analysis

  • Spatial transcriptomics to map expression in tissue context

  • Integrated multi-omics at single-cell resolution

• Advanced protein structure determination:

  • Cryo-EM for membrane protein structure determination

  • AlphaFold2 and similar AI approaches for structure prediction

  • Hydrogen-deuterium exchange mass spectrometry for conformational dynamics

  • Integrative structural biology combining multiple methods

• Functional genomics at scale:

  • CRISPR screens (knockout, activation, inhibition) targeting TMEM158 pathways

  • Base editing for introducing specific mutations

  • Prime editing for precise sequence changes

  • Perturb-seq combining CRISPR perturbations with single-cell readouts

• In situ technology development:

  • Spatial proteomics with multiplexed antibody staining

  • Advanced imaging methods for protein-protein interactions in native context

  • Metabolic labeling approaches for studying protein turnover in vivo

How might understanding TMEM158's role across species advance comparative oncology?

Comparative oncology approaches focusing on TMEM158 offer valuable insights:

• Cross-species conservation analysis:

  • Functional domain conservation across mammals

  • Species-specific regulatory mechanisms

  • Natural knockouts or variants as models for function

  • Correlation with species differences in cancer susceptibility

• Veterinary oncology applications:

  • TMEM158 expression in naturally occurring bovine and canine cancers

  • Comparative pathology across species

  • Shared therapeutic targets between human and animal cancers

  • One Health approach to translational medicine

• Evolutionary perspectives:

  • Positive selection analysis across species

  • Dating of functional innovations in the TMEM158 gene

  • Correlation with tissue-specific expression patterns

  • Integration with cancer-associated phenotypic traits across species

This comparative approach could identify evolutionarily conserved core functions versus species-specific adaptations, informing both basic biology and therapeutic development.

What are the most promising therapeutic strategies targeting TMEM158 in disease?

Based on current knowledge, several therapeutic approaches show particular promise:

• Direct targeting strategies:

  • Small molecule inhibitors targeting transmembrane domains

  • Antibody-drug conjugates targeting extracellular portions

  • RNA interference therapies (siRNA, shRNA) delivered via lipid nanoparticles

  • PROTAC (Proteolysis Targeting Chimera) approach for protein degradation

• Pathway-based approaches:

  • Combined inhibition of TMEM158 and TGF-β pathways

  • Targeting downstream effectors in EMT (SNAIL, ZEB1, Twist1)

  • Context-specific approaches based on cancer type

    • Combination with AR pathway modulators in prostate cancer

    • Combination with hypoxia-targeting agents in lung cancer

• Immunotherapeutic potential:

  • TMEM158 as tumor-associated antigen

  • CAR-T or CAR-NK approaches

  • Bispecific antibodies

  • Immune checkpoint inhibitor combinations based on correlation with anti-tumor immune infiltration

• Biomarker-guided precision medicine:

  • Stratification by TMEM158 expression levels

  • Integration with molecular subtyping

  • Dynamic monitoring during treatment

  • Combination strategies based on pathway activation status