Recombinant Mouse Protein FAM210A (Fam210a)

What is FAM210A and where is it primarily expressed?

FAM210A is a mitochondrial inner membrane protein that regulates the protein synthesis of mitochondrial DNA-encoded genes. It is highly expressed in metabolically active tissues, with the heart showing the highest expression levels, followed by skeletal muscle. Notably, FAM210A is not expressed in bone tissue . The protein contains a mitochondrial targeting signal sequence and functions within the mitochondrial inner membrane to maintain mitochondrial homeostasis and energy production .

What is the fundamental role of FAM210A in cellular function?

FAM210A serves as a mitochondrial translation regulator essential for maintaining mitochondrial homeostasis. It interacts with the mitochondrial translation elongation factor EF-Tu in a protein complex involved in regulating mitochondrial-encoded mRNA translation . This regulatory function is critical for the expression of proteins encoded by the mitochondrial genome, particularly components of the electron transport chain (ETC), which are essential for oxidative phosphorylation and energy production .

How does FAM210A relate to mitochondrial function in different tissues?

In cardiomyocytes, FAM210A maintains normal mitochondrial function by regulating the expression of mitochondrial-encoded ETC proteins, which protects against cardiac stress-induced pathological remodeling . In skeletal muscle, FAM210A expression positively correlates with muscle mass in both mice and humans, and its deletion leads to mitochondrial dysfunction, characterized by disrupted cristae structure and reduced mitochondrial density in myofibers . These tissue-specific effects highlight FAM210A's central role in maintaining mitochondrial function in metabolically demanding tissues.

How does the miR-574-FAM210A axis regulate mitochondrial function?

The miR-574-FAM210A axis represents a novel regulatory mechanism for mitochondrial function. Both the guide strand (miR-574-5p) and passenger strand (miR-574-3p) of miR-574 target FAM210A and modulate its expression. This regulation affects the expression of mitochondrial-encoded ETC proteins but not nuclear-encoded mitochondrial ETC genes . Manipulation of miR-574 levels through genetic knockout or exogenous injection influences the disease phenotype in heart failure models, with miR-574 null mice exhibiting severe cardiac dysfunction under stress conditions . This axis contributes to the maintenance of mitochondrial homeostasis and prevention of pathological cardiac remodeling.

What molecular interactions allow FAM210A to regulate mitochondrial translation?

FAM210A interacts directly with the mitochondrial translation elongation factor EF-Tu in a protein complex involved in the regulation of mitochondrial-encoded mRNA translation . This interaction has been validated through pulldown assays using purified recombinant FAM210A protein and human mitochondrial elongation factor EF-Tu in HEK293T cell lysates . FAM210A deficiency compromises mitochondrial mRNA translation, leading to reduced expression of mitochondrial-encoded proteins and subsequent disruption of mitochondrial proteostasis . This mechanism suggests that FAM210A acts as a scaffold or regulatory component in the mitochondrial translation machinery.

How does FAM210A deficiency affect cellular metabolic pathways?

FAM210A deficiency leads to a cascade of metabolic alterations, including:

• Reversal of the oxidative TCA cycle towards the reductive direction

• Accumulation of acetyl-CoA, resulting in hyperacetylation of cytosolic proteins

• Hyperacetylation of several ribosomal proteins, leading to ribosome disassembly and translational defects

• Increased mitochondrial reactive oxygen species (ROS) production

• Disturbed mitochondrial membrane potential

• Reduced respiratory activity

These metabolic disruptions illustrate how FAM210A deficiency creates an inter-organelle crosstalk between mitochondria and cytosolic ribosomes, ultimately affecting protein synthesis and cellular function .

What mouse models are available for studying FAM210A function?

Several mouse models have been developed to study FAM210A function in different tissues:

• Global miR-574-null mice: These exhibit altered FAM210A expression and serve as a model for studying the miR-574-FAM210A axis in cardiac function .

• Cardiomyocyte-specific conditional knockout: Tamoxifen-induced αMHC MCM-driven conditional knockout of Fam210a in mouse cardiomyocytes leads to progressive dilated cardiomyopathy and heart failure .

• Skeletal muscle-specific knockout: Myl1-driven Cre Fam210a knockout models (Fam210a MKO) show progressive muscle atrophy, systemic metabolic defects, and premature death .

These models provide valuable tools for investigating tissue-specific functions of FAM210A under physiological and pathological conditions, enabling researchers to observe phenotypic changes at molecular, cellular, and organismal levels.

What methods are used to purify recombinant FAM210A protein for biochemical studies?

A successful approach for purifying human FAM210A involves:

• Deletion of the mitochondrial targeting signal sequence

• Using MBP-His10 fusion in Escherichia coli expression systems

• Bacterial cell membrane isolation to recover the recombinant FAM210A protein

• A two-step purification process:

  • Ni-NTA resin-based immobilized-metal affinity chromatography (IMAC)

  • Ion exchange purification

This method results in purified FAM210A protein that retains functionality, as demonstrated by its ability to interact with human mitochondrial elongation factor EF-Tu in pulldown assays . The purified protein can be used for biochemical and structural studies to further elucidate FAM210A's molecular functions and interactions.

What omics approaches have been used to study FAM210A function?

Multiple omics approaches have been employed to understand FAM210A function comprehensively:

• Transcriptomics: RNA-seq analysis identified FAM210A as a hub gene downregulated in cardiac pathological hypertrophy and remodeling compared to physiological hypertrophy .

• Translatomics: Ribosome profiling revealed alterations in translation patterns upon FAM210A deficiency .

• Proteomics: Mass spectrometry analysis identified 157 upregulated and 104 downregulated proteins following FAM210A deletion, with significant correlation between mRNA and protein expression changes .

• Metabolomics: Revealed altered TCA cycle functioning and acetyl-CoA accumulation in FAM210A-deficient tissues .

• Mitochondrial polysome profiling: Demonstrated that FAM210A loss of function compromises mitochondrial mRNA translation, leading to reduced mitochondrial-encoded proteins .

These multi-omics approaches have collectively revealed that FAM210A deficiency activates integrated stress response (ISR), resulting in transcriptomic, translatomic, proteomic, and metabolomic reprogramming .

How does FAM210A dysfunction contribute to cardiac pathologies?

FAM210A dysfunction contributes to cardiac pathologies through several mechanisms:

• Impaired mitochondrial protein synthesis: FAM210A deficiency compromises the translation of mitochondrial-encoded genes essential for electron transport chain function, leading to mitochondrial dysfunction and energy deficits in cardiomyocytes .

• Mitochondrial morphological disruption: Loss of FAM210A causes severe mitochondrial morphological abnormalities and functional decline in cardiomyocytes .

• Activated stress responses: FAM210A deficiency persistently activates integrated stress response (ISR), leading to maladaptive transcriptomic, translatomic, proteomic, and metabolomic reprogramming .

• Increased susceptibility to stress: miR-574-null mice (with altered FAM210A regulation) exhibit severe cardiac dysfunction under stress conditions, while exogenous delivery of miR-574 mimics protects against pathogenesis .

Notably, decreased FAM210A protein expression has been observed in human ischemic heart failure and mouse myocardial infarction tissue samples, suggesting its downregulation may be a key event in the progression of these pathologies .

What is the relationship between FAM210A and skeletal muscle mass?

The expression of FAM210A is positively associated with muscle mass in both mice and humans . Muscle-specific deletion of Fam210a in mice leads to progressive myopathy characterized by:

• Severe muscle weakness and atrophy

• Disrupted mitochondrial cristae structure

• Diminished mitochondrial abundance in myofibers

• Deficiency in mitochondrial energy metabolism

• Induction of mitochondrial proteostatic response and apoptosis

• Abnormal flow of the TCA cycle and accumulation of acetyl-CoA

• Hyperacetylation of ribosomal proteins leading to translational defects

• Systemic metabolic defects and premature death

These findings establish FAM210A as a critical factor in maintaining skeletal muscle health through its role in mitochondrial function and protein synthesis regulation.

How might FAM210A be targeted therapeutically for heart and muscle diseases?

Based on current research, potential therapeutic approaches targeting FAM210A include:

• Gene therapy: AAV9-mediated overexpression of FAM210A has been shown to promote mitochondrial-encoded protein expression, improve cardiac mitochondrial function, and partially rescue murine hearts from cardiac remodeling and damage in ischemia-induced heart failure .

• miRNA-based interventions: Modulation of the miR-574-FAM210A axis, potentially through exogenous delivery of miR-574 mimics, which has been shown to protect against pathogenesis in heart failure models .

• Mitochondrial translation enhancement: Developing compounds that enhance the interaction between FAM210A and EF-Tu to boost mitochondrial translation efficiency in disease states .

• Metabolic pathway modulation: Targeting the acetyl-CoA accumulation and protein hyperacetylation consequences of FAM210A deficiency .

These approaches hold promise for treating ischemic heart disease, dilated cardiomyopathy, and skeletal muscle atrophy conditions where FAM210A dysregulation plays a role.

What are the main challenges in studying FAM210A protein function?

Researchers face several challenges when studying FAM210A:

• Membrane protein isolation: As a mitochondrial inner membrane protein, FAM210A is difficult to isolate while maintaining its native conformation and functional properties .

• Transmembrane nature: The transmembrane domains of FAM210A present challenges for structural studies and biochemical characterization .

• Tissue specificity: FAM210A's varied effects across different tissues necessitate tissue-specific approaches for functional studies .

• Mitochondrial localization: Studying proteins within mitochondria requires specialized techniques to distinguish mitochondrial-encoded versus nuclear-encoded effects .

• Translation regulation complexity: Understanding how FAM210A regulates mitochondrial translation requires sophisticated approaches like mitochondrial polysome profiling .

Overcoming these challenges is essential for comprehensive characterization of FAM210A's structure-function relationships and its potential as a therapeutic target.

How can inconsistencies in FAM210A research findings be reconciled?

When encountering contradictory results in FAM210A research, consider these methodological approaches:

• Tissue-specific differences: FAM210A may have distinct functions in different tissues, so results from cardiac versus skeletal muscle studies may naturally differ .

• Temporal dynamics: The progressive nature of phenotypes in FAM210A deficiency models means that the timing of analysis can significantly impact results .

• Compensatory mechanisms: Acute versus chronic FAM210A deficiency may trigger different compensatory pathways, leading to apparently conflicting observations .

• Experimental models: Different knockout strategies (global vs. conditional, constitutive vs. inducible) may produce varying phenotypes .

• Interaction with environmental factors: Stress conditions may unmask FAM210A-related phenotypes not observable under basal conditions .

Researchers should carefully consider these factors when designing experiments and interpreting results, and explicitly state the experimental conditions and models used.

What are the unexplored aspects of FAM210A biology?

Several aspects of FAM210A biology remain to be fully explored:

• Structural biology: The three-dimensional structure of FAM210A and its complexes with interacting partners like EF-Tu would provide insights into its molecular mechanism .

• Post-translational regulation: How FAM210A itself is regulated post-translationally under different physiological and pathological conditions remains largely unknown.

• Tissue-specific functions: While cardiac and skeletal muscle functions have been studied, FAM210A's role in other metabolically active tissues requires investigation.

• Developmental aspects: The function of FAM210A during embryonic development and growth has not been thoroughly examined.

• Evolutionary conservation: Comparative studies across species could reveal conserved and divergent aspects of FAM210A function.

These unexplored areas present opportunities for researchers to make significant contributions to understanding FAM210A biology.

What novel methodologies might advance FAM210A research?

Emerging methodologies that could advance FAM210A research include:

• Cryo-electron microscopy: For structural determination of FAM210A and its complexes, particularly given the challenges of crystallizing membrane proteins .

• Mitochondria-targeted CRISPR technologies: For precise editing of FAM210A within mitochondria to study its function with minimal disruption to other cellular processes.

• Single-cell multi-omics: To understand cell-to-cell variability in FAM210A expression and function within tissues.

• Organoid models: To study FAM210A in more physiologically relevant systems than traditional cell cultures.

• In vivo imaging of mitochondrial translation: To directly visualize how FAM210A affects mitochondrial protein synthesis in real-time.

Implementing these cutting-edge approaches could overcome current technical limitations and provide new insights into FAM210A biology.

How does mouse FAM210A compare to human FAM210A in structure and function?

Mouse and human FAM210A share high sequence homology and conserved functional domains. Both proteins:

• Localize to the mitochondrial inner membrane

• Interact with mitochondrial translation machinery, specifically EF-Tu

• Regulate mitochondrial-encoded protein synthesis

• Influence mitochondrial function and cellular energy metabolism

What is the relationship between FAM210A and other mitochondrial translation regulators?

FAM210A functions within a network of mitochondrial translation regulators, including:

• EF-Tu (TUFM): FAM210A directly interacts with this mitochondrial translation elongation factor, suggesting functional cooperation in protein synthesis .

• MicroRNAs: The miR-574-FAM210A axis represents a novel regulatory mechanism for mitochondrial translation, potentially interacting with other microRNA-based regulatory pathways .

• Integrated stress response (ISR): FAM210A deficiency activates ISR, which affects numerous aspects of cellular metabolism and translation .

Understanding these relationships is crucial for placing FAM210A within the broader context of mitochondrial homeostasis regulation and identifying potential compensatory mechanisms or therapeutic targets in FAM210A-related disorders.