Recombinant Mouse RING finger protein 122 (Rnf122)

What is the molecular structure of Recombinant Mouse RNF122?

Recombinant Full Length Mouse RING finger protein 122 (Rnf122) is a 155 amino acid protein with multiple functional domains. The protein contains a RING finger domain in the C-terminus and a transmembrane domain in the N-terminus . The amino acid sequence is: MHPFQWCNGCFCGLGLVSTNKSCSMPPISFQDLPLNIYMVIFGTGIFVFMLSLIFCCYFISKLRNQAQSERYGYKEVVLKGDAKKLQLYGQTCAVCLEDFKGKDELGVLPCQHAFHRKCLVKWLEVRCVCPMCNKPIAGPTETSQSIGILLDELV . This structure is crucial for its function as an E3 ubiquitin ligase, particularly the RING finger domain which mediates protein-protein interactions and catalytic activity .

What post-translational modifications occur in RNF122?

RNF122 undergoes several post-translational modifications, with N-linked glycosylation being particularly significant. Experimental evidence shows that RNF122 appears as two distinct bands of approximately 18 kD and 26 kD on western blots, indicating glycosylation . Treatment with tunicamycin, an inhibitor of N-linked glycosylation, causes a shift in protein bands, confirming that RNF122 is an N-linked glycosylated protein . Additionally, RNF122 undergoes ubiquitination as part of its own regulation mechanism, which is dependent on its RING finger domain integrity .

What are the optimal storage conditions for Recombinant Mouse RNF122?

Recombinant Mouse RNF122 protein should be stored at -20°C/-80°C upon receipt, with aliquoting necessary for multiple use to prevent protein degradation . For working stocks, store aliquots at 4°C for up to one week, as repeated freeze-thaw cycles significantly reduce protein activity and should be avoided . The protein is typically supplied as a lyophilized powder in a Tris/PBS-based buffer containing 6% Trehalose at pH 8.0 . For reconstitution, briefly centrifuge the vial prior to opening and reconstitute in deionized sterile water to a concentration of 0.1-1.0 mg/mL, with addition of 5-50% glycerol (recommended final concentration 50%) for long-term storage .

Which expression systems are most effective for producing Recombinant Mouse RNF122?

E. coli is a widely used and effective expression system for producing Recombinant Mouse RNF122 . The commercially available recombinant full-length mouse RNF122 protein (catalog number RFL35729MF) is produced using E. coli expression systems with an N-terminal His tag . This approach allows for high yield and relatively straightforward purification. For studies requiring post-translational modifications like glycosylation, mammalian expression systems may be preferable, though this can affect protein yield and introduces additional purification challenges.

What purification methods are recommended for Recombinant Mouse RNF122?

Affinity chromatography using the His-tag is the primary method for purifying Recombinant Mouse RNF122 . The standardized purification protocol typically involves:

• Immobilized metal affinity chromatography (IMAC) using Ni-NTA or similar resins

• Buffer exchange to remove imidazole using dialysis or size exclusion chromatography

• Quality control by SDS-PAGE to confirm purity greater than 90%

For applications requiring higher purity, additional purification steps such as ion exchange chromatography may be implemented after the initial IMAC purification.

How can researchers validate the functional activity of purified RNF122?

Validation of RNF122 functional activity should focus on its E3 ubiquitin ligase activity. A standard in vitro ubiquitination assay can be performed by combining purified RNF122 with E1, E2 enzymes (particularly UbcH5a, UbcH5b, and UbcH5c), ubiquitin, and ATP . The reaction products can be analyzed by western blotting to detect polyubiquitination. Additionally, mutational analysis of the RING finger domain can serve as a negative control, as mutations in this domain significantly impair the protein's ubiquitin ligase activity . For cellular studies, functional validation can include assessment of JAK/STAT signaling pathway activation, as RNF122 has been shown to regulate this pathway .

What is the role of RNF122 in the ubiquitin proteasome system?

RNF122 functions as an E3 ubiquitin ligase within the ubiquitin proteasome system, catalyzing the final step in the ubiquitination cascade by facilitating the transfer of ubiquitin from an E2 conjugating enzyme to target substrates . Importantly, RNF122 can catalyze its own ubiquitination (auto-ubiquitination), thereby regulating its own degradation through the proteasome pathway . This auto-regulatory mechanism is dependent on an intact RING finger domain, as mutations in this domain result in increased protein stability by preventing auto-ubiquitination . In vitro ubiquitination assays demonstrate that RNF122 preferentially works with specific E2 enzymes including UbcH5a, UbcH5b, and UbcH5c to facilitate polyubiquitination .

How does RNF122 interact with the JAK/STAT signaling pathway?

RNF122 plays a significant role in modulating the JAK/STAT signaling pathway, particularly in the context of glioblastoma progression . Experimental evidence using Cignal Finder Cancer 10-Pathway Reporter Kits shows that knockdown of RNF122 significantly suppresses the JAK/STAT signaling axis in LN-229 and A-172 glioblastoma cells . Gene Set Enrichment Analysis (GSEA) further confirms a strong correlation between RNF122 expression and JAK/STAT signaling . Specifically, RNF122 appears to regulate the expression and phosphorylation status of multiple components in the pathway, including JAK1, JAK2, STAT1, STAT2, STAT3, and downstream effector c-Myc . This regulation has functional consequences for cell proliferation, migration, and invasion in cancer contexts.

What experimental approaches can be used to study RNF122's effect on cell cycle regulation?

To study RNF122's effect on cell cycle regulation, researchers can employ the following methodological approaches:

• RNA interference (RNAi): Using siRNA targeting RNF122 (e.g., si-RNF122) to knock down expression in cell lines such as LN-229 and A-172 .

• Flow cytometry analysis: After RNF122 knockdown or overexpression, cells can be analyzed by flow cytometry to determine cell cycle distribution. Research shows that RNF122 knockdown results in G1 phase arrest .

• Proliferation assays: In vitro cell proliferation can be assessed using methods such as MTT/CCK-8 assays, colony formation assays, or BrdU incorporation .

• In vivo tumor growth studies: Using xenograft models with RNF122 knockdown or overexpression to assess tumor growth rates and proliferative index via Ki-67 immunofluorescence staining .

• Western blot analysis: To examine the expression of cell cycle regulators and downstream effectors of JAK/STAT signaling that may mediate RNF122's effects on cell cycle progression .

How does RNF122 contribute to tumor progression in glioblastoma models?

RNF122 significantly contributes to glioblastoma (GBM) progression through multiple mechanisms centered around the JAK2/STAT3/c-Myc signaling axis . In both in vitro and in vivo experimental models, RNF122 enhances GBM cell growth and cell cycle progression . Knockdown of RNF122 in GBM cell lines (LN-229 and A-172) significantly inhibits cell proliferation, migration, and invasion capabilities . This effect was further verified through in vivo animal experiments, where tumors with RNF122 knockdown showed reduced proliferation as measured by Ki-67 immunofluorescence staining .

Mechanistically, RNF122 activates the JAK/STAT signaling pathway, particularly the JAK2/STAT3/c-Myc axis . Western blot analysis reveals that RNF122 modulates the expression and phosphorylation status of JAK2, STAT3, and c-Myc . Analysis of The Cancer Genome Atlas (TCGA) data also demonstrates that RNF122 is overexpressed in gliomas and inversely correlated with patient outcomes, highlighting its clinical significance .

What are the key structural elements that determine RNF122's ubiquitin ligase activity?

The key structural elements determining RNF122's ubiquitin ligase activity include:

• RING finger domain: Located in the C-terminus, this domain is critical for catalyzing the transfer of ubiquitin from E2 enzymes to substrates . Mutation studies demonstrate that an intact RING finger domain is essential for RNF122's auto-ubiquitination and degradation through the proteasome pathway .

• E2 enzyme selectivity: RNF122 displays specificity for certain E2 ubiquitin-conjugating enzymes, particularly UbcH5a, UbcH5b, and UbcH5c . This selectivity is likely determined by specific amino acid residues within the RING finger domain that mediate E2 enzyme binding.

• Transmembrane domain: Located in the N-terminus, this domain influences RNF122's subcellular localization and potentially its access to specific substrates or regulatory proteins .

• N-linked glycosylation sites: The presence of N-linked glycosylation affects RNF122's structure and potentially its stability or activity .

These structural elements work together to determine RNF122's substrate specificity, catalytic efficiency, and regulatory mechanisms.

What biomarker potential does RNF122 have in glioma prognosis and stratification?

RNF122 shows significant potential as a biomarker for glioma prognosis and patient stratification based on several lines of evidence:

• Expression correlation with clinical outcomes: TCGA database analysis demonstrates that RNF122 is overexpressed in gliomas and inversely related to patient outcomes .

• Predictive value in ROC analysis: Receiver operating characteristic curve (ROC) analysis reveals that a combination model incorporating RNF122 expression and WHO grade exhibits superior predictive ability for clinical outcomes compared to the WHO grade-based model alone .

• Association with clinicopathological characteristics: Analysis of 112 glioma patients showed that RNF122 mRNA expression levels significantly correlate with tumor size, suggesting its utility in assessing disease progression .

• Molecular pathway association: RNF122's established role in activating the JAK2/STAT3/c-Myc signaling axis, which is known to drive aggressive tumor behavior, provides a mechanistic basis for its prognostic value .

These findings suggest that RNF122 expression levels could be used as part of a multi-parameter assessment to improve patient stratification, predict treatment response, and potentially guide personalized therapeutic approaches in glioma management.

What are the common challenges in working with Recombinant Mouse RNF122 and how can they be addressed?

Working with Recombinant Mouse RNF122 presents several challenges that researchers should be prepared to address:

• Protein stability issues: RNF122 undergoes auto-ubiquitination leading to proteasomal degradation . This can be mitigated by:

  • Using proteasome inhibitors (e.g., MG132) when studying the protein in cellular contexts

  • Creating RING domain mutants for stability studies

  • Storing the recombinant protein with 5-50% glycerol at appropriate temperatures (-20°C/-80°C)

• Glycosylation heterogeneity: As an N-linked glycosylated protein, RNF122 can show heterogeneous bands on western blots . Researchers can:

  • Use tunicamycin to inhibit N-linked glycosylation for certain experiments

  • Consider deglycosylation enzymes (PNGase F) for specific applications requiring homogeneous protein

• E2 enzyme specificity: RNF122 works preferentially with specific E2 enzymes (UbcH5a, UbcH5b, UbcH5c) . In ubiquitination assays, researchers should:

  • Test multiple E2 enzymes to identify optimal activity

  • Include appropriate positive and negative controls

How can researchers optimize experimental conditions for studying RNF122's role in cell signaling pathways?

To optimize experimental conditions for studying RNF122's role in cell signaling pathways, researchers should consider:

• Cell line selection: Different cell lines may express varying levels of JAK/STAT pathway components. GBM cell lines like LN-229 and A-172 have been successfully used to study RNF122's effects on JAK/STAT signaling .

• Knockdown efficiency verification: When using siRNA approaches, validate knockdown efficiency by western blot. Select siRNAs with highest knockdown efficiency (e.g., si-RNF122#2 as noted in one study) .

• Pathway analysis tools: Utilize comprehensive pathway screening tools such as the Cignal Finder Cancer 10-Pathway Reporter Kits to identify affected signaling pathways .

• Rescue experiments: Perform rescue experiments by reintroducing wild-type or mutant RNF122 in knockdown cells to confirm specificity of observed effects .

• Protein phosphorylation analysis: When studying JAK/STAT pathway components, assess both total protein levels and phosphorylation status of key components including JAK1, p-JAK1, JAK2, p-JAK2, STAT1, p-STAT1, STAT2, p-STAT2, STAT3, p-STAT3, and c-Myc .

What are the recommended controls and validation approaches for RNF122 functional studies?

For robust RNF122 functional studies, the following controls and validation approaches are recommended:

• Expression controls:

  • Positive control: Cells treated with proteasome inhibitor MG132 to prevent RNF122 degradation

  • Negative control: RING finger domain mutant RNF122 that lacks ubiquitin ligase activity

• Knockdown validation:

  • Multiple siRNA sequences targeting different regions of RNF122 mRNA

  • Western blot confirmation of knockdown efficiency

  • qRT-PCR for mRNA level validation

• Ubiquitination assay controls:

  • Reaction mixtures lacking E1, E2, or ATP as negative controls

  • Testing multiple E2 enzymes (UbcH5a, UbcH5b, UbcH5c) to confirm specificity

  • Including wild-type and RING domain mutant proteins for comparison

• In vivo validation:

  • Appropriate sample sizes for statistical significance

  • Multiple assessment methods (e.g., tumor volume measurements, Ki-67 staining)

  • Correlation with clinical samples when available

• Pathway analysis validation:

  • Orthogonal confirmation methods (e.g., reporter assays, western blot, GSEA)

  • Rescue experiments with JAK/STAT pathway inhibitors or activators

  • Correlation with downstream biological effects (proliferation, migration, etc.)

How does mouse RNF122 compare to human RNF122 in terms of structure and function?

While the search results don't provide direct comparative data between mouse and human RNF122, both species' proteins contain critical RING finger domains in the C-terminus and transmembrane domains in the N-terminus . This structural conservation suggests functional similarity. Commercial suppliers offer recombinant forms of both human RNF122 (catalog RFL3018HF) and mouse RNF122 (catalog RFL35729MF) , allowing researchers to conduct comparative studies. Additionally, the availability of recombinant RNF122 from other species such as rhesus monkey (catalog RNF122-3926R) enables evolutionary and comparative functional studies across species.

What experimental models are most appropriate for studying RNF122 function in different disease contexts?

Based on the current research, the following experimental models are recommended for studying RNF122 function in different disease contexts:

• Glioblastoma/Cancer research:

  • Cell lines: LN-229 and A-172 glioblastoma cells have been validated for RNF122 studies

  • Animal models: Xenograft models using RNF122 knockdown or overexpressing cell lines

  • Patient-derived samples: Analysis of RNF122 expression in relation to clinical parameters and outcomes

• Ubiquitin-proteasome system studies:

  • HeLa and HEK293T cells with MG132 treatment to study RNF122 degradation mechanisms

  • In vitro ubiquitination assays with purified components to study enzyme specificity

  • RING domain mutants to study structure-function relationships

• JAK/STAT signaling research:

  • Reporter systems such as Cignal Finder Cancer 10-Pathway Reporter Kits

  • Cell-based assays measuring STAT phosphorylation and nuclear translocation

  • Gene expression analysis of JAK/STAT target genes

Each model system offers distinct advantages for addressing specific research questions related to RNF122 function in normal physiology or disease states.

What are the current gaps in RNF122 research and promising future directions?

Several significant gaps and promising future directions in RNF122 research include:

• Substrate identification: While RNF122's auto-ubiquitination activity is established , its physiological substrates beyond self-regulation remain largely unknown. Future studies using proteomics approaches (e.g., ubiquitin remnant profiling) could identify novel RNF122 substrates.

• Structural biology: Detailed structural studies of RNF122, particularly co-crystal structures with E2 enzymes or substrates, would provide valuable insights into its mechanism of action and potential for targeted modulation.

• Tissue-specific functions: The physiological role of RNF122 in different tissues and developmental stages remains inadequately characterized. Conditional knockout models could help elucidate tissue-specific functions.

• Therapeutic targeting: Given RNF122's role in glioblastoma progression via the JAK2/STAT3/c-Myc pathway , developing specific inhibitors of RNF122 or its interactions could represent a novel therapeutic approach. High-throughput screening for small molecule modulators of RNF122 activity is a promising direction.

• Biomarker validation: While initial studies suggest RNF122's potential as a prognostic biomarker in glioma , larger validation studies across diverse patient cohorts are needed to establish its clinical utility.

• Regulatory mechanisms: The factors controlling RNF122 expression, localization, and activity beyond auto-ubiquitination are not fully understood. Investigation of transcriptional, post-transcriptional, and post-translational regulation of RNF122 would fill important knowledge gaps.