Recombinant Human Protein FAM87B (FAM87B)

What is FAM87B and what is its genomic location?

FAM87B (Family with sequence similarity 87, member B) is a gene located on the long arm of chromosome 11 (11q13.4) in humans. It encodes a protein known as the FAM87B protein, though recent research has also characterized it as a long non-coding RNA (lncRNA) with significant biological functions . This dual characterization reflects the evolving understanding of genomic elements that may have multiple functional roles depending on cellular context.

What are the primary cellular functions of FAM87B?

FAM87B protein plays crucial roles in various cellular processes, particularly in protein degradation and vesicle trafficking pathways. It is involved in the assembly of the ESCRT (Endosomal Sorting Complexes Required for Transport) complex, which facilitates the sorting and transport of proteins and lipids from endosomes to lysosomes for degradation . As an lncRNA, FAM87B appears to have regulatory functions that influence gene expression patterns, particularly in neural tissues and certain cancer types .

What diseases have been associated with FAM87B mutations or expression changes?

FAM87B has been implicated in several neurological disorders and cancers. Mutations in the FAM87B gene have been associated with Charcot-Marie-Tooth disease type 2E (CMT2E), frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), and amyotrophic lateral sclerosis (ALS) . Additionally, aberrant FAM87B expression has been linked to glioma development and progression, with higher expression levels observed in glioblastomas (GBM) .

How prevalent are FAM87B mutations in neurological disorders?

Studies have indicated that mutations in the FAM87B gene account for approximately 1-2% of cases of Charcot-Marie-Tooth disease type 2E (CMT2E), making it a relatively rare but significant contributor to this condition . The prevalence of FAM87B mutations in other associated disorders like FTDP-17 and ALS is still being investigated, with preliminary data suggesting varying frequencies across different populations.

What are the optimal methods for detecting FAM87B expression in tissue samples?

For effective detection of FAM87B expression in tissue samples, a multi-modality approach is recommended:

• RNA-level detection: Quantitative RT-PCR remains the gold standard for measuring FAM87B transcript levels, with primers designed to target specific exons depending on whether protein-coding or non-coding variants are being investigated.

• Protein-level detection: Immunohistochemistry (IHC) or Western blotting using validated antibodies against FAM87B can verify protein expression. When selecting antibodies, consider epitope specificity and potential cross-reactivity with related family members.

• In situ detection: RNA in situ hybridization techniques such as RNAscope can provide spatial information about FAM87B expression in intact tissue sections, which is particularly valuable for heterogeneous tissues like brain or tumor samples.

When analyzing glioma samples specifically, correlation with other molecular markers such as IDH mutation status and 1p/19q codeletion should be performed for comprehensive characterization .

What expression systems are most effective for producing recombinant FAM87B?

Based on structural characteristics and research practices for similar proteins, the following expression systems offer distinct advantages for recombinant FAM87B production:

• Bacterial systems (E. coli): Most economical but may require optimization for proper folding of human proteins. Consider using fusion tags (His, GST, MBP) to enhance solubility and facilitate purification.

• Mammalian expression systems (HEK293, CHO cells): Provide appropriate post-translational modifications and protein folding environment. Particularly recommended when studying functional interactions with human protein partners.

• Insect cell systems (Sf9, High Five): Offer a balance between proper eukaryotic processing and higher yield compared to mammalian systems.

For functional studies, mammalian systems are generally preferable to ensure native folding and modification patterns, particularly when investigating ESCRT complex interactions.

How does FAM87B expression correlate with glioma progression and patient outcomes?

FAM87B expression has shown significant correlation with glioma pathogenesis and clinical outcomes. Analysis of RNA-seq data from multiple databases (CGGA mRNAseq_325, CGGA mRNAseq_693, TCGA mRNAseq_glioma, and TCGA mRNAseq_LGG) has revealed that FAM87B expression levels are highly correlated with:

• Pathological grade of gliomas, with significantly higher expression in higher-grade tumors

• Molecular classification of gliomas

• Patient prognosis and survival outcomes

• Notably elevated expression in glioblastomas (GBM) compared to lower-grade gliomas

These correlations suggest FAM87B may serve as both a diagnostic and prognostic biomarker for glioma patients.

What molecular characteristics of glioma correlate with FAM87B expression?

FAM87B expression levels have been found to associate with several classical molecular characteristics of glioma, including:

• Isocitrate dehydrogenase (IDH) mutation status

• 1p/19q codeletion status

• Other molecular signatures that define glioma subtypes

This correlation pattern indicates that FAM87B may be integrated into the molecular pathways that drive glioma development and progression, potentially offering insights into tumor biology and treatment response prediction.

What are the potential mechanisms by which FAM87B influences glioma development?

While detailed mechanistic studies are still emerging, several hypothesized pathways exist by which FAM87B may influence glioma development:

• Regulation of ESCRT complex function: As FAM87B is involved in ESCRT complex assembly, dysregulation could affect cellular protein homeostasis and vesicular trafficking, potentially contributing to tumor cell survival and invasion .

• Epigenetic regulation: As an lncRNA, FAM87B may influence chromatin structure or interact with transcription factors that regulate oncogenes or tumor suppressor genes.

• Signaling pathway modulation: FAM87B might interact with key signaling molecules involved in cell proliferation, apoptosis, or migration that are frequently altered in gliomas.

Experimental approaches to elucidate these mechanisms include CRISPR-mediated knockout/knockdown studies, RNA immunoprecipitation to identify protein partners, and chromatin immunoprecipitation to identify DNA binding sites if acting as a transcriptional regulator.

How can FAM87B be leveraged as a biomarker or therapeutic target for glioma?

FAM87B shows considerable promise as both a biomarker and therapeutic target for glioma management:

As a biomarker:

• Diagnostic application: Quantification of FAM87B expression in tissue or potentially liquid biopsies could aid in glioma diagnosis and classification.

• Prognostic stratification: Expression levels could help predict patient outcomes and inform treatment decisions.

• Treatment response monitoring: Changes in FAM87B expression during therapy might indicate treatment efficacy.

As a therapeutic target:

• RNA interference approaches: siRNA or antisense oligonucleotides targeting FAM87B could be developed to reduce its expression in glioma cells.

• CRISPR-based gene editing: For permanent modification of FAM87B expression.

• Small molecule inhibitors: If functional domains of FAM87B protein are identified, targeted inhibitors could be designed to disrupt its activity .

The development of FAM87B-targeted therapeutics would require further validation of its causative role in glioma progression rather than being merely correlative.

What experimental models are most appropriate for studying FAM87B function?

For comprehensive investigation of FAM87B function, researchers should consider these experimental models:

• In vitro cellular models:

  • Patient-derived glioma cell lines with varying FAM87B expression levels

  • Genetically modified cell lines with FAM87B knockout/overexpression

  • Neuronal cell lines for studying FAM87B's role in neurological disorders

• In vivo models:

  • Transgenic mouse models with FAM87B modifications

  • Orthotopic xenograft models using FAM87B-modified glioma cells

  • Patient-derived xenografts to maintain tumor heterogeneity

• Ex vivo models:

  • Organotypic brain slice cultures for studying FAM87B in a more physiologically relevant environment

  • Patient-derived organoids to model disease-specific contexts

When selecting appropriate models, consider the specific disease context (neurological disorder vs. cancer) and whether protein-coding or non-coding functions of FAM87B are being investigated.

How does FAM87B interact with the ESCRT complex in protein degradation pathways?

FAM87B's interaction with the ESCRT complex represents a critical aspect of its cellular function. The ESCRT complex facilitates the sorting and transport of proteins and lipids from endosomes to lysosomes for degradation . Current understanding suggests:

• FAM87B may act as a regulatory component or cofactor in ESCRT complex assembly

• It potentially mediates specific substrate recognition within the degradation pathway

• FAM87B might influence the efficiency of vesicle formation or cargo sorting

Research approaches to further characterize these interactions include:

• Co-immunoprecipitation studies to identify direct binding partners within the ESCRT machinery

• Proximity labeling techniques (BioID, APEX) to map the spatial organization of FAM87B relative to ESCRT components

• Live-cell imaging with fluorescently tagged proteins to visualize dynamic interactions during vesicle formation

Understanding these interactions could provide insights into both normal cellular homeostasis and disease states where protein degradation pathways are dysregulated.

What are the priorities for future FAM87B research?

Several key areas represent priorities for advancing FAM87B research:

• Resolving functional classification: Clarifying whether FAM87B functions primarily as a protein-coding gene, a long non-coding RNA, or has dual functionality depending on cellular context .

• Mechanistic studies: Elucidating the precise molecular mechanisms by which FAM87B influences disease processes, particularly in glioma and neurological disorders.

• Therapeutic development: Exploring the feasibility of targeting FAM87B for treatment of associated conditions, including development of specific inhibitors or modulators.

• Biomarker validation: Conducting larger clinical studies to validate the utility of FAM87B as a diagnostic, prognostic, or predictive biomarker.

• Structural characterization: Determining the three-dimensional structure of FAM87B protein to inform rational drug design approaches.

• Regulatory network mapping: Identifying upstream regulators and downstream effectors of FAM87B to place it within broader cellular pathways.

What technological advances would accelerate FAM87B research?

Emerging technologies that could significantly advance FAM87B research include:

• Single-cell multi-omics: Integrating single-cell RNA-seq, ATAC-seq, and proteomics to understand FAM87B regulation and function at unprecedented resolution.

• CRISPR-based screening: Using CRISPR activation/inhibition libraries to identify genetic modifiers of FAM87B function.

• Spatial transcriptomics: Mapping FAM87B expression patterns within tissues to understand its distribution in heterogeneous environments like brain tissue or tumors.

• Cryo-EM and structural proteomics: Enabling detailed structural analysis of FAM87B and its interaction partners.

• AI-driven protein modeling: Leveraging artificial intelligence approaches to predict functional domains and interaction sites when experimental structural data is limited.

• Nanobody and aptamer development: Creating highly specific detection reagents for FAM87B to improve visualization and quantification in complex samples.