GO:0055005 ventricular cardiac myofibril assembly: Sarcomere Assembly, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0055005 ventricular cardiac myofibril assembly describes the progression of the ventricular cardiac myofibril from formation to mature structure, a process specific to cardiac muscle cells.
• Cardiac sarcomere assembly is mechanosensitive: mechanical stress and force generation through beta-cardiac myosin, titin and alpha-actinin drive myofibril assembly from cell-matrix adhesions.
• Nonmuscle alpha-actinin-4 couples sarcomere function to cardiac remodeling, showing that myofibril assembly is linked to broader ventricular remodeling programs.
• Formin FHOD3-mediated actin elongation is required for sarcomere integrity in cardiomyocytes, identifying actin nucleation as a key step in myofibril assembly.
• Titin truncating variants cause location-dependent cardiac and skeletal muscle dysfunction, demonstrating that sarcomere protein dosage and isoform balance are critical for ventricular myofibril assembly.
• Zebrafish heart regeneration studies show that Cited4a limits cardiomyocyte dedifferentiation and proliferation, linking myofibril disassembly and reassembly to regenerative capacity.
Description
Ventricular cardiac myofibril assembly (GO:0055005) is the biological process whose specific outcome is the progression of the ventricular cardiac myofibril over time, from its formation to the mature structure. A cardiac myofibril is a myofibril specific to cardiac muscle cells, and its assembly is fundamental to the contractile function of the ventricular myocardium. This process is not a simple linear assembly line but a mechanosensitive, force-driven program in which nascent sarcomeres are built from cell-matrix adhesions and remodeled in response to mechanical load. Researchers study GO:0055005 because defects in myofibril assembly underlie a broad spectrum of cardiomyopathies, arrhythmias and regenerative failure. Understanding the molecular choreography of ventricular cardiac myofibril assembly is therefore essential for interpreting genetic variants, designing disease models and developing therapeutic strategies.
ventricular cardiac myofibril assembly At A Glance
| GO ID | GO:0055005 |
|---|---|
| GO term | ventricular cardiac myofibril assembly |
| Ontology | biological_process |
| Synonym | ventricular cardiac myofibril development; ventricular heart myofibril development |
| Major function | Progression of the ventricular cardiac myofibril from formation to mature structure in cardiac muscle cells |
| Definition source | QuickGO definition: The process whose specific outcome is the progression of the ventricular cardiac myofibril over time, from its formation to the mature structure. A cardiac myofibril is a myofibril specific to cardiac muscle cells. |
| Tissue context | Ventricular myocardium; cardiac muscle cells |
| Key structural unit | Cardiac myofibril and its sarcomeres |
| Related processes | Mechanical stress-induced sarcomere assembly; cardiac remodeling; cardiomyocyte dedifferentiation and proliferation |
What Is GO:0055005?
In our own words, GO:0055005 ventricular cardiac myofibril assembly is the developmental and homeostatic process by which the contractile myofibril of ventricular cardiac muscle cells is built, matures and becomes functional. It encompasses the temporal progression from initial sarcomere formation to the mature myofibril structure, and it is restricted to cardiac muscle cells rather than skeletal muscle. The process includes the assembly of sarcomeric protein complexes, their mechanical integration with cell-matrix adhesions, and the force-dependent remodeling that establishes mature ventricular myofibril architecture.
Why Is ventricular cardiac myofibril assembly Important in Cell Biology?
Ventricular cardiac myofibril assembly is important because the myofibril is the contractile machine of the heart, and its correct assembly determines whether the ventricle can generate force efficiently. Disruption of this process by mutations in sarcomeric proteins such as titin or by altered actin dynamics through FHOD3 leads to cardiac dysfunction and disease. Moreover, the capacity to disassemble and reassemble myofibrils is central to cardiomyocyte dedifferentiation and heart regeneration, as shown in zebrafish models. Because nonmuscle alpha-actinin-4 can couple sarcomere function to cardiac remodeling, myofibril assembly is also mechanistically linked to pathological ventricular remodeling. Studying GO:0055005 therefore informs cardiomyopathy genetics, regenerative biology and the development of targeted cardiac therapies.
• Defines the core contractile assembly program of ventricular cardiomyocytes.
• Mechanical stress and force generation are direct drivers of sarcomere assembly, linking biomechanics to gene regulation.
• Mutations in titin cause location-dependent cardiac and skeletal muscle dysfunction, implicating myofibril assembly in titinopathies.
• Nonmuscle alpha-actinin-4 couples sarcomere function to cardiac remodeling, connecting assembly to ventricular remodeling.
• FHOD3-mediated actin elongation is required for sarcomere integrity, highlighting actin nucleation in myofibrillogenesis.
• Cited4a limits cardiomyocyte dedifferentiation and proliferation during zebrafish heart regeneration, linking myofibril dynamics to regeneration.
• Provides a mechanistic framework for interpreting sarcomeric gene variants in cardiomyopathy and arrhythmia.
• Supports the development of CRISPR models to test causality of candidate genes in myofibril assembly.
• Informs regenerative strategies that aim to re-enter the myofibril assembly program after injury.
• Connects cell-matrix adhesions to sarcomere assembly, revealing adhesion-based therapeutic targets.
What Happens During ventricular cardiac myofibril assembly?
Initiation at cell-matrix adhesions
In simple terms: The myofibril starts to build at the points where the cell grips the surrounding matrix.
Ventricular cardiac myofibril assembly begins at cell-matrix adhesions, where force generation via beta-cardiac myosin, titin and alpha-actinin drives the assembly of the cardiac sarcomere. This initiation step couples the extracellular mechanical environment to intracellular sarcomere formation, establishing the first organized contractile units. Mechanical stress is a key trigger for sarcomere assembly during cardiac muscle growth in both length and width.
Actin filament elongation and sarcomere integrity
In simple terms: Long actin filaments are built by a formin protein, and without this step the sarcomere falls apart.
Human formin FHOD3-mediated actin elongation is required for sarcomere integrity in cardiomyocytes, identifying actin nucleation and elongation as an essential step in ventricular cardiac myofibril assembly. FHOD3 activity supports the formation of actin thin filaments that integrate into nascent sarcomeres, and loss of this activity compromises sarcomere integrity. This step ensures that the actin scaffold is properly sized and organized before thick filament incorporation.
Mechanosensitive growth in length and width
In simple terms: The myofibril grows longer and wider in response to mechanical load.
Mechanical stress-induced sarcomere assembly drives cardiac muscle growth in both length and width, meaning that ventricular cardiac myofibril assembly is a mechanosensitive process that continuously adapts to hemodynamic load. This growth involves the addition of sarcomeres in series and in parallel, and it is regulated by the mechanical forces experienced by cardiomyocytes. The process is therefore not completed at birth but remains dynamic in the adult heart.
Coupling to cardiac remodeling
In simple terms: The sarcomere is not isolated; it talks to the rest of the cell to control heart remodeling.
Nonmuscle alpha-actinin-4 couples sarcomere function to cardiac remodeling, demonstrating that ventricular cardiac myofibril assembly is functionally integrated with broader remodeling pathways. This coupling means that changes in sarcomere assembly can propagate to remodeling responses, and vice versa. The finding expands the role of myofibril assembly beyond a purely structural process to a signaling hub.
Dedifferentiation and regenerative plasticity
In simple terms: Heart muscle cells can take apart their myofibrils to divide and regenerate, and a protein called Cited4a keeps this in check.
Cited4a limits cardiomyocyte dedifferentiation and proliferation during zebrafish heart regeneration, showing that myofibril disassembly and reassembly are tightly controlled during regenerative responses. This implies that ventricular cardiac myofibril assembly is not only a developmental process but also a reversible program that can be re-entered after injury. Understanding this plasticity is relevant for promoting cardiac regeneration in mammals.
Key Genes Involved in GO:0055005 ventricular cardiac myofibril assembly
The following genes and proteins have been experimentally implicated in ventricular cardiac myofibril assembly or in closely related sarcomere assembly processes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MYH7 | Beta-cardiac myosin heavy chain; generates force that drives sarcomere assembly from cell-matrix adhesions | Core sarcomeric motor; target for cardiomyopathy variant modeling |
| TTN | Titin; giant sarcomeric protein providing elasticity and scaffolding during myofibril assembly | Truncating variants cause location-dependent cardiac and skeletal muscle dysfunction |
| ACTN2 | Alpha-actinin-2; crosslinks actin filaments at the Z-disc | Essential for sarcomere assembly and force transmission |
| ACTN4 | Nonmuscle alpha-actinin-4; couples sarcomere function to cardiac remodeling | Links myofibril assembly to ventricular remodeling pathways |
| FHOD3 | Formin; mediates actin elongation required for sarcomere integrity | Key actin nucleation factor in cardiomyocyte sarcomere assembly |
| CITED4 | Transcriptional cofactor; limits cardiomyocyte dedifferentiation and proliferation | Regulates regenerative plasticity and myofibril disassembly |
| MYBPC3 | Myosin binding protein C; modulates thick filament assembly and stability | Frequently mutated in hypertrophic cardiomyopathy; relevant to myofibril assembly |
| TNNT2 | Cardiac troponin T; regulates thin filament activation | Sarcomeric component; candidate for assembly studies |
| TNNI3 | Cardiac troponin I; inhibits actomyosin ATPase | Sarcomeric regulatory protein; disease relevance |
| TPM1 | Alpha-tropomyosin; stabilizes actin thin filaments | Thin filament component in myofibril assembly |
| MYL2 | Regulatory myosin light chain; modulates myosin motor activity | Ventricular-specific myosin light chain |
| MYL3 | Essential myosin light chain; stabilizes myosin head | Sarcomeric structural component |
| DES | Desmin; intermediate filament protein linking sarcomeres to cytoskeleton | Cytoskeletal integration in myofibril assembly |
| VCL | Vinculin; links cell-matrix adhesions to actin cytoskeleton | Adhesion-based initiation of sarcomere assembly |
| ITGB1 | Integrin beta-1; mediates cell-matrix adhesion | Upstream of force-driven sarcomere assembly |
| BMP pathway components | BMP signaling regulates cardiac contraction and myofibril function | 3-OST-7 regulates BMP-dependent cardiac contraction |
| 3-OST-7 | Heparan sulfate 3-O-sulfotransferase; regulates BMP-dependent cardiac contraction | Modulates cardiac contraction and myofibril function |
How Is ventricular cardiac myofibril assembly Regulated?
Ventricular cardiac myofibril assembly is regulated by mechanical stress, which induces sarcomere assembly for cardiac muscle growth in length and width. Force generation through beta-cardiac myosin, titin and alpha-actinin at cell-matrix adhesions acts as a driver of assembly, making the process mechanosensitive. BMP signaling regulates cardiac contraction, and 3-OST-7 modulates BMP-dependent cardiac contraction, providing a signaling layer of control over myofibril function. Cited4a acts as a brake on cardiomyocyte dedifferentiation and proliferation, thereby regulating the disassembly-reassembly balance during regeneration. Nonmuscle alpha-actinin-4 couples sarcomere function to cardiac remodeling, indicating that remodeling pathways feed back on myofibril assembly.
ventricular cardiac myofibril assembly and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TTN | Titin truncating variants cause atrial fibrillation and location-dependent cardiac and skeletal muscle dysfunction | Knock-in of truncating variant in iPSC-derived cardiomyocytes |
| ACTN4 | Nonmuscle alpha-actinin-4 couples sarcomere function to cardiac remodeling | Knockout and overexpression in cardiomyocyte models |
| FHOD3 | FHOD3-mediated actin elongation is required for sarcomere integrity | Knockout in human iPSC-derived cardiomyocytes |
| CITED4 | Cited4a limits cardiomyocyte dedifferentiation and proliferation during heart regeneration | Zebrafish knockout and overexpression |
| 3-OST-7 | Regulates BMP-dependent cardiac contraction | Zebrafish knockout and rescue |
Titin truncating variants and cardiomyopathy
Titin truncating variants linked to atrial fibrillation increase atrial profibrotic signaling and cholinergic sensitivity, showing that titin truncation alters cardiac signaling beyond structural roles. Location-dependent differences in cardiac and skeletal muscle dysfunction associated with truncating titin (ttn.2) variants demonstrate that the position of the truncation determines the severity and tissue specificity of disease. These findings directly implicate ventricular cardiac myofibril assembly in titin-related cardiomyopathies and arrhythmias.
Sarcomere remodeling and heart failure
Nonmuscle alpha-actinin-4 couples sarcomere function to cardiac remodeling, linking myofibril assembly to pathological ventricular remodeling. This connection suggests that defects in myofibril assembly can drive remodeling and heart failure progression. Targeting this coupling may offer therapeutic opportunities in remodeling-associated disease.
Regenerative failure and cardiomyocyte dedifferentiation
Cited4a limits cardiomyocyte dedifferentiation and proliferation during zebrafish heart regeneration, indicating that the ability to disassemble and reassemble myofibrils is a determinant of regenerative capacity. In mammals, limited cardiomyocyte dedifferentiation contributes to regenerative failure, and understanding this process may inform strategies to promote heart repair. This links ventricular cardiac myofibril assembly to regenerative medicine.
Actin dynamics and sarcomere integrity disorders
Human formin FHOD3-mediated actin elongation is required for sarcomere integrity in cardiomyocytes, so defects in actin nucleation can cause sarcomere disorganization. Such disorganization is expected to impair ventricular cardiac myofibril assembly and contractile function. This highlights FHOD3 as a candidate gene for sarcomere integrity disorders.
From ventricular cardiac myofibril assembly-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene required for ventricular cardiac myofibril assembly? | CRISPR knockout in iPSC-derived cardiomyocytes or zebrafish |
| Does a specific sarcomeric variant impair myofibril assembly? | CRISPR point mutation knock-in in iPSC-derived cardiomyocytes |
| Can a disease-associated variant be corrected to restore assembly? | CRISPR knock-in of wild-type allele or base editing |
| Where does a sarcomeric protein localize during assembly? | Endogenous tagged knock-in with fluorescent tag |
| Does overexpression of a factor enhance or disrupt myofibril assembly? | CRISPR overexpression or cDNA overexpression in cardiomyocytes |
| What is the role of a nonmuscle protein in sarcomere remodeling? | Knockout and overexpression in cardiac cell models |
How to Study the ventricular cardiac myofibril assembly Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescence microscopy | Localization and organization of sarcomeric proteins | Visualizing myofibril assembly progression |
| Live-cell imaging | Dynamic sarcomere addition and remodeling | Mechanosensitive growth in length and width |
| RNA sequencing | Transcriptional programs during assembly | Identifying regulators such as Cited4a |
| Proteomics | Sarcomeric protein abundance and modifications | Quantifying assembly stoichiometry |
| Contractility assay | Force generation and calcium handling | Functional validation of assembly defects |
| CRISPR knockout screening | Genes required for sarcomere integrity | Discovery of assembly factors |
| Zebrafish regeneration assay | Cardiomyocyte dedifferentiation and proliferation | Studying regenerative myofibril dynamics |
| CRISPR knock-in | Effect of specific variants on assembly | Modeling titin truncating variants |
Live-cell and fixed imaging of sarcomere assembly
Fluorescence imaging of sarcomeric proteins such as alpha-actinin, titin and myosin allows visualization of myofibril assembly progression in cardiomyocytes. Live-cell imaging can capture the dynamic addition of sarcomeres and the mechanosensitive growth in length and width. Tagged knock-in models enable tracking of endogenous proteins during assembly.
Transcriptomics and proteomics of myofibril assembly
RNA sequencing can identify transcriptional programs associated with ventricular cardiac myofibril assembly, including regulators such as Cited4a. Proteomics can quantify sarcomeric protein stoichiometry and post-translational modifications during assembly. These approaches help define the molecular signature of assembling versus mature myofibrils.
Functional contractility assays
Contractility assays measure force generation and calcium handling, which reflect the functional output of ventricular cardiac myofibril assembly. Zebrafish models allow assessment of cardiac contraction in vivo, as shown for BMP-dependent cardiac contraction regulated by 3-OST-7. Combining contractility with structural imaging links assembly to function.
Genetic and CRISPR screening
CRISPR knockout screens can identify genes required for sarcomere integrity and myofibril assembly. Candidate validation using point mutations and knock-ins can test the causality of specific variants. Zebrafish regeneration models can screen for regulators of myofibril disassembly and reassembly.
How CRISPR Can Be Used to Study GO:0055005 ventricular cardiac myofibril assembly
Knockout
CRISPR knockout of candidate genes such as FHOD3 or ACTN4 in cardiomyocytes can test whether they are required for ventricular cardiac myofibril assembly. Knockout of Cited4a in zebrafish can reveal its role in limiting dedifferentiation and proliferation during regeneration. Knockout models provide loss-of-function evidence for gene essentiality in myofibril assembly.
Point Mutation
CRISPR point mutation knock-in can introduce disease-associated variants, such as titin truncating variants, into endogenous loci to study their effect on myofibril assembly. This approach preserves endogenous regulatory context and reveals location-dependent effects of truncations. Point mutation models are essential for interpreting clinical variants of uncertain significance.
Knock-in
CRISPR knock-in of fluorescent tags or reporter cassettes allows tracking of sarcomeric proteins during assembly. Knock-in of wild-type alleles can rescue assembly defects caused by disease variants. Tagged knock-in models enable live imaging of myofibril assembly dynamics.
Overexpression
CRISPR overexpression or cDNA overexpression of factors such as alpha-actinin-4 or FHOD3 can test whether increased dosage enhances or disrupts myofibril assembly. Overexpression in zebrafish can assess effects on cardiac contraction and regeneration. These models complement knockout studies by revealing gain-of-function phenotypes.
How EDITGENE Supports ventricular cardiac myofibril assembly Research
Researchers studying ventricular cardiac myofibril assembly-related genes often need to determine whether a candidate gene is causally involved in sarcomere formation, integrity or remodeling. Establishing causality requires precise genetic models that can knock out, mutate, tag or overexpress the gene of interest in relevant cardiac cell types. EDITGENE provides a comprehensive suite of CRISPR services tailored to these needs, enabling rigorous functional interrogation of myofibril assembly genes.
Contact EDITGENE today to design your custom CRISPR model for ventricular cardiac myofibril assembly research.
Frequently Asked Questions About ventricular cardiac myofibril assembly
What is GO:0055005 ventricular cardiac myofibril assembly?
GO:0055005 is the biological process describing the progression of the ventricular cardiac myofibril from formation to mature structure in cardiac muscle cells.
What genes are involved in ventricular cardiac myofibril assembly?
Key genes include MYH7, TTN, ACTN2, ACTN4, FHOD3 and CITED4, among other sarcomeric and regulatory factors.
Why is ventricular cardiac myofibril assembly important?
It builds the contractile machinery of the heart, and its disruption causes cardiomyopathies, arrhythmias and regenerative failure.
How is ventricular cardiac myofibril assembly regulated?
It is regulated by mechanical stress, force generation through myosin, titin and alpha-actinin, BMP signaling and factors such as Cited4a.
What diseases are linked to ventricular cardiac myofibril assembly?
Titin truncating variants cause atrial fibrillation and cardiac dysfunction, and defects in actin elongation cause sarcomere disorganization.
What methods are used to study ventricular cardiac myofibril assembly?
Fluorescence imaging, live-cell imaging, RNA sequencing, proteomics, contractility assays and CRISPR screening are commonly used.
How can CRISPR help study ventricular cardiac myofibril assembly?
CRISPR knockout, point mutation, knock-in and overexpression models allow causal testing of genes and variants in myofibril assembly.
What is the role of titin in ventricular cardiac myofibril assembly?
Titin provides elasticity and scaffolding, and truncating variants cause location-dependent cardiac and skeletal muscle dysfunction.
What is the role of FHOD3 in sarcomere assembly?
FHOD3-mediated actin elongation is required for sarcomere integrity in cardiomyocytes.
What is the role of Cited4a in heart regeneration?
Cited4a limits cardiomyocyte dedifferentiation and proliferation during zebrafish heart regeneration, regulating myofibril disassembly and reassembly.
Conclusion
Ventricular cardiac myofibril assembly (GO:0055005) is a mechanosensitive, force-driven process that builds the contractile machinery of the heart from cell-matrix adhesions to mature sarcomeres. Its molecular players, including beta-cardiac myosin, titin, alpha-actinin, FHOD3 and Cited4a, connect assembly to cardiac remodeling, disease and regeneration. Understanding this process is essential for interpreting sarcomeric variants and for developing therapeutic strategies in cardiomyopathy and regenerative medicine.
References
- 1. Hayes JB et al.. 2026. Nonmuscle α-Actinin-4 Couples Sarcomere Function to Cardiac Remodeling.. Circ Res 138(1):e326412 PMID: 41255333
- 2. Forman-Rubinsky R et al.. 2025. Cited4a limits cardiomyocyte dedifferentiation and proliferation during zebrafish heart regeneration.. Development 152(20) PMID: 40698412
- 3. Cumberland MJ et al.. 2026. A titin truncating variant linked to atrial fibrillation increases atrial profibrotic signalling and cholinergic sensitivity.. Cardiovasc Res 122(9):1206-1223 PMID: 42198882
- 4. Santiago CF et al.. 2026. Location-Dependent Differences in Cardiac and Skeletal Muscle Dysfunction Associated With Truncating Titin (ttn.2) Variants.. Circ Res 138(3):e325999 PMID: 41498146
- 5. Samson SC et al.. 2013. 3-OST-7 regulates BMP-dependent cardiac contraction.. PLoS Biol 11(12):e1001727 PMID: 24311987
- 6. Russell B et al.. 2010. Mechanical stress-induced sarcomere assembly for cardiac muscle growth in length and width.. J Mol Cell Cardiol 48(5):817-23 PMID: 20188736
- 7. Chopra A et al.. 2018. Force Generation via β-Cardiac Myosin, Titin, and α-Actinin Drives Cardiac Sarcomere Assembly from Cell-Matrix Adhesions.. Dev Cell 44(1):87-96.e5 PMID: 29316444
- 8. Valencia DA et al.. 2025. Human formin FHOD3-mediated actin elongation is required for sarcomere integrity in cardiomyocytes.. Elife 13 PMID: 40663059
