Recombinant Chicken Protein FAM210A (FAM210A)

What is FAM210A and where is it localized in cells?

FAM210A (Family with sequence similarity 210 member A) is a mitochondrial inner membrane protein that regulates the protein synthesis of mitochondrial DNA encoded genes . It contains a transmembrane domain that allows it to integrate into the mitochondrial inner membrane. The protein is involved in various cellular processes, particularly those related to mitochondrial function, and has been implicated in the development and maintenance of both bone and muscle tissue . Structurally, FAM210A contains a DUF1279 domain that is responsible for binding to mitochondrial translation factors.

How conserved is FAM210A across species?

FAM210A is highly conserved across evolutionary lineages, with the gene being present in at least 213 different organisms . This conservation spans across humans, dogs, cows, mice, rats, chickens, zebrafish, and frogs, suggesting that the protein serves fundamental cellular functions that have been preserved throughout evolution . The high degree of conservation makes comparative studies between species particularly informative, as findings in one model organism may have direct relevance to understanding the function in others, including humans.

What are the known functions of FAM210A in cellular processes?

Current research indicates that FAM210A plays multiple roles in cellular functioning. Primarily, it regulates mitochondrial protein synthesis by interacting with mitochondrial translation factors, including EF-Tu (elongation factor Tu), GFM2 (mitochondrial ribosome releasing factor), ATAD3A, and LRPPRC . Beyond its mitochondrial functions, FAM210A has been implicated in maintaining bone mineral density and muscle strength, as evidenced by studies showing that genetic variants in the FAM210A region are significantly associated with bone mineral density and fracture risk . Additionally, knockout mouse models demonstrate reduced grip strength and decreased lean mass, further supporting its role in musculoskeletal development .

What expression systems are most effective for producing recombinant FAM210A?

For recombinant FAM210A production, researchers have successfully utilized both bacterial and plant-based expression systems. For human FAM210A, an effective method involves using an MBP-His₁₀ fusion protein expressed in Escherichia coli . This approach leverages the bacterial system's high yield while maintaining protein functionality. Alternatively, wheat germ expression systems have been employed to produce full-length human FAM210A (1-272 amino acids), which is suitable for applications such as ELISA and Western blotting . For chicken FAM210A specifically, researchers should consider modifying the human FAM210A expression protocol, taking into account species-specific differences in the protein sequence and post-translational modifications.

How can FAM210A be purified to maintain its functional properties?

A validated purification protocol for transmembrane FAM210A involves a two-step process. First, after expression in E. coli, the recombinant protein is inserted into the bacterial cell membrane and then isolated from these membranes . Subsequently, purification proceeds through Ni-NTA resin-based immobilized-metal affinity chromatography (IMAC) followed by ion exchange purification . This method has been shown to maintain the functional properties of FAM210A, as evidenced by pulldown assays demonstrating that the purified protein can still interact with human mitochondrial elongation factor EF-Tu in HEK293T cell lysates . When working with transmembrane proteins like FAM210A, using appropriate detergents during extraction and purification is critical to maintain the native conformation and functional interactions.

What methods can verify the functional activity of purified FAM210A?

The functional activity of purified FAM210A can be verified through several complementary approaches. Pulldown assays have been successfully employed to confirm that purified FAM210A maintains its ability to interact with known binding partners, particularly mitochondrial elongation factor EF-Tu . Immunoprecipitation followed by immunoblotting (IP-IB) can validate endogenous interactions between FAM210A and its binding partners such as EF-Tu and ATAD3A . Additionally, domain mapping using truncated FAM210A mutants has revealed that the DUF1279 domain is responsible for binding EF-Tu and ATAD3A . For studies focusing on the role of FAM210A in mitochondrial protein synthesis, researchers can assess changes in the expression of mitochondrially encoded proteins following FAM210A manipulation.

How does FAM210A influence mitochondrial protein synthesis?

FAM210A regulates mitochondrial protein synthesis through direct interactions with key mitochondrial translation factors. Research has shown that FAM210A binds to critical components of the mitochondrial translation machinery, including TUFM/EF-Tu (elongation factor), GFM2 (mitochondrial ribosome releasing factor), ATAD3A, and LRPPRC . The DUF1279 domain of FAM210A mediates these interactions, while the C-terminal coiled-coil (CC) domain appears to serve as a regulatory module that can influence the strength of these interactions . Deletion studies have shown that removing the CC domain enhances FAM210A's binding to translation factors, suggesting that this domain normally moderates these interactions. By interacting with these translation factors, FAM210A likely influences the efficiency and accuracy of mitochondrial protein synthesis, particularly for proteins encoded by the mitochondrial genome.

What is the relationship between FAM210A and bone/muscle development?

FAM210A plays a significant role in both bone and muscle development, as evidenced by both genetic association studies and experimental models. Genome-wide association studies (GWAS) have identified that SNPs in the FAM210A genomic region are significantly associated with bone mineral density (BMD) and fracture risk in humans. Specifically, rs1941749 shows strong association with BMD (P = 3.5 × 10⁻⁴³), while rs4796995 is associated with fracture risk (P = 8.8 × 10⁻¹³) .

In knockout mouse models (Fam210a⁻/⁻), significant phenotypic changes in both bone and muscle parameters have been observed:

Table 1: Phenotypic Changes in Fam210a⁻/⁻ Mice Compared to Controls

These findings suggest that FAM210A is essential for normal bone remodeling and muscle development, potentially through its mitochondrial functions that support the high energy demands of these tissues .

How is FAM210A expression regulated by microRNAs?

FAM210A expression is regulated by microRNA-574, specifically by both miR-574-5p and miR-574-3p strands. Research has identified two functional target sites for miR-574-5p and one site for miR-574-3p in the 3'UTR of Fam210a mRNA . Dual luciferase reporter assays have validated these as direct targets, with mutation of the seed sequences abolishing the inhibitory effects of miR-574-5p .

The regulatory relationship has been confirmed in vivo, as knockout mice lacking miR-574 (miR-574⁻/⁻) show increased expression of Fam210a at both the mRNA and protein levels . This regulatory mechanism appears particularly important in cardiac tissue, where FAM210A protein levels are dynamically regulated during cardiac stress. Following transverse aortic constriction (TAC) surgery, FAM210A protein expression increases at later stages (day 14 and 21) in wild-type mice but is significantly induced at early stages in miR-574⁻/⁻ mice . Therapeutic approaches using nanoparticle delivery of miR-574 mimics have been shown to reduce FAM210A protein expression, decrease reactive oxygen species (ROS) production, and restore ATP production in mouse models of cardiac stress .

What challenges might researchers encounter when working with transmembrane proteins like FAM210A?

Working with transmembrane proteins like FAM210A presents several technical challenges. First, the hydrophobic nature of the transmembrane domain can lead to protein aggregation during expression and purification, compromising both yield and functionality. To address this, researchers have developed a specialized protocol using MBP-His₁₀ fusion tags that improve solubility while facilitating purification . Additionally, when extracting FAM210A from membranes, the choice of detergent is critical—too harsh a detergent may denature the protein, while insufficient detergent may fail to extract it efficiently.

Another significant challenge is maintaining protein functionality throughout the purification process. The published protocols for FAM210A purification specifically address this by isolating bacterial cell membranes where the recombinant protein has inserted, followed by carefully optimized conditions for the two-step purification process . Researchers should verify functionality through interaction studies, such as pulldown assays with known binding partners like EF-Tu, to confirm that the purified protein retains its biological activity . For structural studies, additional optimization may be required to obtain protein samples suitable for techniques like X-ray crystallography or cryo-electron microscopy.

How can researchers distinguish between direct and indirect effects when studying FAM210A function?

Distinguishing between direct and indirect effects of FAM210A requires a multi-faceted experimental approach. Domain mapping studies have proven valuable in identifying the specific regions of FAM210A that mediate protein-protein interactions. For example, research has shown that the DUF1279 domain directly mediates binding to translation factors like EF-Tu and ATAD3A .

To establish causality in functional studies, researchers should employ:

• Rescue experiments: After FAM210A knockdown or knockout, reintroducing wild-type FAM210A should restore normal function, while mutated versions affecting specific domains should fail to rescue or partially rescue the phenotype.

• Direct binding assays: Using purified components to demonstrate direct physical interactions, such as surface plasmon resonance or isothermal titration calorimetry.

• Structure-function studies: Creating point mutations or domain deletions to pinpoint specific residues or regions critical for particular functions.

• Temporal control systems: Using inducible expression or degradation systems to examine the immediate versus delayed consequences of FAM210A manipulation.

These approaches help distinguish primary effects directly mediated by FAM210A from secondary effects that arise as downstream consequences of altered cellular function.

How should researchers interpret conflicting data on FAM210A function across different model systems?

When faced with conflicting data on FAM210A function across different model systems, researchers should consider several factors. First, despite its high conservation across species, FAM210A may have acquired species-specific functions or regulatory mechanisms. The research shows that FAM210A is conserved across 213 organisms , but this does not preclude evolutionary divergence in specific aspects of its function.

Second, tissue-specific effects should be considered. Studies have revealed distinct phenotypes in bone and muscle tissues in FAM210A knockout mice , while other research has focused on cardiac tissue and mitochondrial functions . The protein may have different roles depending on the cellular context and the specific demands of different tissues.

Third, experimental conditions can significantly influence outcomes. For example, stress conditions like transverse aortic constriction (TAC) in cardiac studies reveal phenotypes that might not be apparent under basal conditions . Similarly, the developmental stage of the organism may influence FAM210A's role, as its function may change during development versus adult homeostasis.

To reconcile conflicting data, researchers should:

• Directly compare experimental protocols, including the specific protein constructs, expression systems, and assay conditions used

• Consider whether differences in genetic background of model organisms might explain discrepancies

• Examine whether the conflicting results might actually reveal different facets of a complex, multifunctional protein

• Design experiments that directly test competing hypotheses in a single model system

What are the key knowledge gaps in FAM210A research?

Despite significant advances in understanding FAM210A, several critical knowledge gaps remain. First, the precise molecular mechanism by which FAM210A regulates mitochondrial protein synthesis is not fully elucidated. While its interactions with translation factors like EF-Tu are established , how these interactions influence the efficiency or specificity of mitochondrial translation requires further investigation.

Second, the regulatory network controlling FAM210A expression beyond miR-574 remains largely unexplored. Understanding the complete transcriptional and post-transcriptional regulation of FAM210A would provide insights into its tissue-specific functions and its role in disease states.

Third, the potential role of FAM210A in pathological conditions beyond musculoskeletal phenotypes, particularly in mitochondrial diseases, deserves examination. Given its conservation and fundamental role in mitochondrial function, FAM210A may have broader implications for diseases characterized by mitochondrial dysfunction.

Finally, the three-dimensional structure of FAM210A remains to be determined. Structural studies would enhance our understanding of how this protein interacts with its binding partners and how these interactions are regulated, potentially opening avenues for therapeutic modulation.

What novel technologies could advance FAM210A research?

Several cutting-edge technologies could significantly advance FAM210A research. CRISPR-Cas9 genome editing enables precise modification of FAM210A in various model systems, facilitating the creation of knockout models, point mutations, and tagged versions of the endogenous protein. This approach allows for more physiologically relevant studies than traditional overexpression systems.

Cryo-electron microscopy could be employed to determine the structure of FAM210A, particularly in complex with its binding partners. Recent advances in this technology have made it increasingly feasible to study membrane proteins like FAM210A at near-atomic resolution, potentially revealing critical insights into its function.

Proximity labeling approaches such as BioID or APEX could map the complete interactome of FAM210A in different cellular contexts, expanding our understanding beyond the few interaction partners currently identified . This would provide a more comprehensive view of FAM210A's functional networks.

Single-cell technologies, including single-cell RNA-seq and spatial transcriptomics, could reveal cell type-specific expression patterns and functions of FAM210A, particularly in heterogeneous tissues like bone and muscle where multiple cell types contribute to tissue function and development.

How might findings from FAM210A research translate to therapeutic applications?

Research on FAM210A has potential therapeutic implications, particularly for conditions affecting musculoskeletal health and mitochondrial function. The strong association between FAM210A genetic variants and bone mineral density suggests that modulating FAM210A activity could influence bone remodeling and potentially address conditions like osteoporosis . Similarly, the role of FAM210A in muscle development and function suggests potential applications in addressing muscle wasting disorders or sarcopenia.

The emerging understanding of microRNA regulation of FAM210A, particularly by miR-574, presents a potential therapeutic avenue. Studies have already demonstrated that delivery of miR-574 mimics can modulate FAM210A expression and improve outcomes in models of cardiac stress . Similar approaches might be adapted for other tissues where FAM210A plays important roles.

For mitochondrial diseases, which often lack effective treatments, understanding FAM210A's role in mitochondrial protein synthesis could inform the development of therapies that target this pathway. As FAM210A appears to serve as a regulator of mitochondrial translation, modulating its activity might help address conditions characterized by defects in mitochondrial protein production.