rnf185 Antibody

What is RNF185 and what biological functions does it serve?

RNF185 (Ring Finger Protein 185) is an E3 ubiquitin-protein ligase with a molecular weight of approximately 20.5 kDa and 192 amino acids in its canonical human form . It contains a RING domain characteristic of ubiquitin E3 ligases and shares approximately 70% sequence identity with RNF5 .

RNF185 serves several critical cellular functions:

• Regulates selective mitochondrial autophagy by mediating 'Lys-63'-linked polyubiquitination of BNIP1

• Functions in the endoplasmic reticulum-associated degradation (ERAD) pathway, targeting misfolded proteins for ubiquitination and subsequent degradation

• Protects cells from ER stress-induced apoptosis

• Regulates innate antiviral responses through 'Lys-27'-linked polyubiquitination of cGAS

• Modulates SARS-CoV-2 envelope protein stability, affecting viral replication

RNF185 is ubiquitously expressed across many tissue types and has up to two reported isoforms .

Where is RNF185 localized within cells?

RNF185 exhibits dual localization patterns that are critical for its diverse functions:

• Primary localization: RNF185 is predominantly found on the endoplasmic reticulum (ER) membrane, consistent with its role in the ERAD pathway

• Secondary localization: RNF185 is also present in mitochondria, supporting its role in mitochondrial autophagy processes

Confocal microscopy and subcellular fractionation analyses have confirmed this dual localization pattern . In experimental settings, this dual localization necessitates careful consideration of sample preparation methods to preserve both ER and mitochondrial structures.

What are the common applications of RNF185 antibodies in research?

Based on commercial availability and published research, RNF185 antibodies are most commonly used in the following applications:

When selecting an RNF185 antibody, researchers should consider validation data provided by manufacturers for their specific application and the species reactivity that matches their experimental model .

How does RNF185 regulate the cGAS-mediated antiviral response?

RNF185 enhances the cGAS-mediated antiviral response through specific protein interactions and post-translational modifications:

• RNF185 directly interacts with cGAS through its RING domain (amino acids 39-80), binding to the C-terminal domain of cGAS (amino acids 201-522)

• This interaction is significantly enhanced upon viral infection, such as HSV-1

• RNF185 catalyzes K27-linked polyubiquitination of cGAS at 'Lys-173' and 'Lys-384'

• This polyubiquitination does not lead to cGAS degradation but instead potentiates cGAS enzymatic activity

• Enhanced cGAS activity increases production of type I interferons and other antiviral genes

Experimental evidence shows that knockdown of RNF185 significantly attenuates the expression of IRF3-responsive genes (Ifnb, Ifna4, and Cxcl10) in response to DNA virus infection but not RNA virus infection, indicating specificity for the cytosolic DNA sensing pathway .

Interestingly, RNF185 mRNA expression has been found to be significantly upregulated in systemic lupus erythematosus (SLE) patients compared to healthy controls, suggesting a potential role in autoimmune conditions .

What role does RNF185 play in SARS-CoV-2 infection?

RNF185 has been identified as a critical regulator of SARS-CoV-2 envelope protein stability:

• RNF185 targets the SARS-CoV-2 envelope protein for ubiquitination and subsequent proteasomal degradation

• The envelope protein co-localizes with RNF185 in the endoplasmic reticulum

• CRISPR-Cas9 knockout of RNF185 results in a 2-3 fold increase in SARS-CoV-2 envelope protein levels

• RNF185 knockout increases SARS-CoV-2 viral titer by approximately 60% across multiple variants (WA, Beta, and Delta)

• This regulatory mechanism appears specific to SARS-CoV and SARS-CoV-2, as MERS envelope protein stability was not affected by RNF185 depletion

These findings suggest RNF185 may function as part of the host's antiviral defense by limiting the availability of essential viral structural components. This represents a potential therapeutic avenue, as enhancing the interaction between RNF185 and the SARS-CoV-2 envelope protein could reduce viral replication .

How can researchers validate RNF185 antibody specificity?

Validating antibody specificity is crucial for ensuring reliable experimental results. For RNF185 antibodies, consider these validation approaches:

The effectiveness of these validation methods may vary depending on the application. For instance, an antibody that works well for Western blot may not necessarily work for immunoprecipitation or immunofluorescence .

What are the best approaches for studying RNF185-mediated ubiquitination?

When investigating RNF185's E3 ligase activity and ubiquitination functions:

• Control constructs: Use RNF185 C39A mutant as a negative control—it lacks E3 ligase activity but retains substrate binding capability

• Ubiquitin chain specificity assessment:

  • For studying K27-linked ubiquitination (relevant for cGAS modification)

  • For studying K63-linked ubiquitination (relevant for BNIP1 and mitophagy)

• Substrate identification:

  • Use mass spectrometry approaches after RNF185 immunoprecipitation

  • Employ ubiquitin remnant profiling in control vs. RNF185 knockout cells

• E2 enzyme partners:

  • Focus on interactions with UBE2J1 and UBE2J2, which preferentially associate with RNF185

  • Use reciprocal co-immunoprecipitation to confirm interactions

• Inhibitor studies:

  • Use proteasome inhibitors (e.g., MG132) to accumulate ubiquitinated substrates

  • Employ deubiquitinating enzyme inhibitors to preserve ubiquitination status

When designing ubiquitination experiments, consider using cycloheximide chase assays to monitor protein stability and turnover rates of putative RNF185 substrates.

What experimental challenges might arise when using RNF185 antibodies?

Researchers may encounter several challenges when working with RNF185 antibodies:

• Low endogenous expression: RNF185 may be expressed at low levels in some cell types, making detection challenging without signal amplification

• Isoform specificity: The presence of up to 2 different isoforms could complicate interpretation if the antibody recognizes only specific isoforms

• Cross-reactivity concerns: Due to the high sequence homology with RNF5 (approximately 70%), some antibodies might cross-react with this related protein

• Post-translational modifications: Ubiquitination or other modifications of RNF185 itself might mask epitopes recognized by certain antibodies

• Subcellular localization complexity: Since RNF185 is present in both ER and mitochondria, appropriate sample preparation methods must preserve these structures for localization studies

• Epitope accessibility: The transmembrane nature of RNF185 may require optimization of extraction conditions to maintain antibody recognition sites

To address these challenges, researchers should carefully select antibodies with well-documented validation data for their specific application and experimental system.

How does the choice of RNF185 antibody affect experimental outcomes in different systems?

The choice of RNF185 antibody can significantly impact experimental outcomes:

For studying specific functions:

• When investigating ERAD pathway interactions, antibodies recognizing the ER-facing domains are preferable

• For studying cGAS interactions, antibodies that don't interfere with the RING domain (aa 39-80) should be used

• When examining SARS-CoV-2 envelope interactions, consider antibodies that preserve the native conformation of RNF185

How does RNF185 interact with the ERAD pathway and what are the implications for experimental design?

RNF185's role in the ERAD pathway has several important implications for experimental design:

• RNF185 targets misfolded proteins in the ER for ubiquitination and subsequent proteasome-mediated degradation

• It is responsible for the cotranslational ubiquitination and degradation of CFTR in the ERAD pathway

• RNF185 protects cells from ER stress-induced apoptosis

• It preferentially associates with E2 enzymes UBE2J1 and UBE2J2, known components of ERAD machinery

Experimental design implications:

• Use proteasome inhibitors (e.g., MG132) to accumulate ubiquitinated substrates when studying RNF185 ERAD functions

• Consider ER stress inducers (e.g., tunicamycin, thapsigargin) to upregulate ERAD components and potentially modulate RNF185 activity

• Include TMEM259 (a member of the ERAD complex required for RNF185 function) as a factor in experimental designs

• Incorporate proper controls for ER localization in immunofluorescence studies

• Assess both steady-state levels and turnover rates when studying potential ERAD substrates of RNF185

What are promising areas for future RNF185 research?

Based on current knowledge gaps and emerging findings, several promising research directions include:

• Therapeutic targeting for viral infections:

  • Development of small molecules that enhance RNF185-SARS-CoV-2 envelope protein interaction

  • Investigation of RNF185 activity modulators as broad-spectrum antiviral agents

• Role in autoimmune conditions:

  • Further exploration of elevated RNF185 expression in SLE patients

  • Investigating RNF185 as a biomarker or therapeutic target in autoimmune diseases

• Mitochondrial quality control:

  • Deeper characterization of RNF185's role in mitophagy beyond BNIP1 ubiquitination

  • Investigation of potential mitochondrial substrates

• Structural biology approaches:

  • Determination of RNF185 crystal structure to facilitate rational drug design

  • Characterization of the structural basis for substrate specificity

• Systems biology integration:

  • Network analysis of RNF185 in ubiquitination cascades

  • Multi-omics approaches to identify comprehensive lists of RNF185 substrates

Future research efforts that combine these approaches with advanced technologies like CRISPR screens, proteomics, and high-throughput drug screening may yield significant insights into RNF185 biology and therapeutic applications.