GO:0097130 cyclin D3-CDK4 complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0097130 defines the cyclin D3-CDK4 complex, a heterodimeric serine/threonine kinase holoenzyme in which cyclin D3 serves as the regulatory subunit and CDK4 as the catalytic subunit.
• The complex is a key driver of G1-phase progression and the restriction point, phosphorylating pRb to license S-phase entry.
• Its activity is modulated by stoichiometric inhibitors such as p27Kip1 and p21Cip1, which can be found in the holoenzyme and influence its assembly and function.
• Pharmacological CDK4/6 inhibitors such as PD0332991 paradoxically stabilize activated cyclin D3-CDK4/6 complexes, revealing a dynamic regulation of complex turnover.
• Cyclin D3-CDK4 is implicated in T-cell leukemia and thyroid epithelial cell proliferation, making it a candidate therapeutic target.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable precise interrogation of cyclin D3-CDK4 complex function in disease contexts.
Description
The cyclin D3-CDK4 complex (GO:0097130) is a cellular component defined as a protein complex consisting of cyclin D3 and cyclin-dependent kinase 4 (CDK4). Cyclins are characterized by periodicity in protein abundance throughout the cell cycle, and cyclin-dependent kinases represent a family of serine/threonine protein kinases that become active upon binding to a cyclin regulatory partner. This complex is a central regulator of the G1-to-S transition, and its assembly and activity are tightly controlled by mitogenic signals and cell-cycle inhibitors. Researchers study this complex to understand how cells commit to division and how dysregulation contributes to diseases such as cancer. The cyclin D3-CDK4 holoenzyme has been biochemically characterized in fibroblasts and thyroid epithelial cells, where its interactions with p27Kip1 and p21Cip1 modulate its kinase activity. Its ability to phosphorylate the retinoblastoma protein (pRb) is critical for cell-cycle progression, and the specificity of pRb phosphorylation differs between CDK4 activated by cyclin D1 versus cyclin D3. This article provides a comprehensive overview of the cyclin D3-CDK4 complex, covering its structure, regulation, disease relevance, and experimental approaches for studying it.
cyclin D3-CDK4 complex At A Glance
| GO ID | GO:0097130 |
|---|---|
| GO term | cyclin D3-CDK4 complex |
| Ontology | cellular_component |
| Synonym | None |
| Major function | Serine/threonine kinase activity; phosphorylates pRb to promote G1/S transition |
| Complex subunits | Cyclin D3 (regulatory) and CDK4 (catalytic) |
| Associated regulators | p27Kip1, p21Cip1, and CDK4/6 inhibitors such as PD0332991 |
| Cellular context | Nucleus and cytoplasm; dynamically assembled in response to mitogenic signals |
What Is GO:0097130?
The cyclin D3-CDK4 complex is a heterodimeric protein complex composed of the regulatory cyclin D3 subunit and the catalytic cyclin-dependent kinase 4 (CDK4) subunit. Cyclin D3 levels oscillate during the cell cycle, and its binding to CDK4 activates the kinase, enabling phosphorylation of target substrates such as the retinoblastoma protein (pRb). This complex functions as a serine/threonine kinase and is a key component of the cell-cycle machinery that controls the G1-to-S phase transition.
Why Is cyclin D3-CDK4 complex Important in Cell Biology?
The cyclin D3-CDK4 complex is essential for cell-cycle progression and is frequently dysregulated in cancer. Its kinase activity drives phosphorylation of the retinoblastoma protein, releasing E2F transcription factors and enabling S-phase entry. Understanding its assembly, regulation, and substrate specificity is critical for developing targeted therapies, as evidenced by the clinical use of CDK4/6 inhibitors and the observation that these inhibitors can paradoxically stabilize the complex. Moreover, the complex is a therapeutic target in T-cell leukemia, where cyclin D3-CDK4/6 inhibition shows efficacy.
• Controls the G1-to-S cell-cycle transition by phosphorylating pRb.
• Integrates mitogenic signals through cyclic AMP-dependent phosphorylation of CDK4.
• Modulated by stoichiometric inhibitors p27Kip1 and p21Cip1, affecting complex assembly and activity.
• Targeted by CDK4/6 inhibitors, which can stabilize the complex.
• Implicated in T-cell leukemia, where its inhibition is therapeutic.
• Plays a role in thyroid epithelial cell proliferation and differentiation.
• Involved in the regulation of the corpus luteum formation and maintenance.
• Linked to aging and myotonic dystrophy through the GSK3beta-cyclin D3-CUGBP1-eIF2 pathway.
• Exhibits distinct pRb phosphorylation specificity compared to cyclin D1-CDK4.
• Serves as a model for studying cell-cycle kinase holoenzyme assembly and regulation.
Structure and Composition of cyclin D3-CDK4 complex
Cyclin D3: The Regulatory Subunit
In simple terms: Cyclin D3 is the partner protein that activates CDK4.
Cyclin D3 is a D-type cyclin that binds to and activates CDK4. Its abundance fluctuates during the cell cycle, and it is essential for the formation of the active holoenzyme. Cyclin D3-CDK4 complexes have been analyzed in fibroblasts expressing and lacking p27Kip1 and p21Cip1, showing that cyclin D3 is a key component of these complexes. In thyroid epithelial cells, cyclin D3-bound CDK4 is phosphorylated in a cyclic AMP-dependent manner, which determines passage through the restriction point.
CDK4: The Catalytic Subunit
In simple terms: CDK4 is the enzyme that does the chemical work of adding phosphate groups to target proteins.
CDK4 is a serine/threonine protein kinase that becomes active upon binding to cyclin D3. It phosphorylates substrates such as the retinoblastoma protein (pRb). The kinase activity of CDK4 is regulated by phosphorylation events, including cyclic AMP-dependent phosphorylation when bound to cyclin D3. The cyclin D3-CDK4-p27Kip1 holoenzyme in thyroid epithelial cells is activated by TSH and inhibited by TGFbeta, demonstrating the dynamic regulation of CDK4 activity.
Assembly and Stoichiometry
In simple terms: The complex forms when cyclin D3 and CDK4 bind together, often with additional regulatory proteins.
The assembly of the cyclin D3-CDK4 complex is influenced by the presence of CDK inhibitors. In fibroblasts, the formation of cyclin D3-CDK4 complexes was analyzed in the presence and absence of p27Kip1 and p21Cip1, revealing that these inhibitors can be part of the complex. The cyclin D3-CDK4-p27Kip1 holoenzyme has been characterized in thyroid epithelial cells, where its subunit phosphorylations were demonstrated by two-dimensional gel electrophoresis. The stoichiometry of the complex can be altered by pharmacological inhibitors; PD0332991 paradoxically stabilizes activated cyclin D3-CDK4/6 complexes.
Subcellular Localization and Dynamics
In simple terms: The complex moves within the cell and its levels change during the cell cycle.
The cyclin D3-CDK4 complex is dynamically regulated throughout the cell cycle. Levels and interactions of p27, cyclin D3, and CDK4 were studied during the formation and maintenance of the corpus luteum in mice, showing changes in complex composition. The complex can be found in both nucleus and cytoplasm, and its assembly is responsive to mitogenic signals such as TSH in thyroid epithelial cells. The GSK3beta-cyclin D3-CUGBP1-eIF2 pathway links cyclin D3 to aging and myotonic dystrophy, indicating broader cellular roles.
Key Genes Involved in GO:0097130 cyclin D3-CDK4 complex
The following genes and proteins are central to the composition, regulation, and function of the cyclin D3-CDK4 complex.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CCND3 | Encodes cyclin D3, the regulatory subunit of the complex | Essential for complex formation and activation of CDK4 |
| CDK4 | Encodes the catalytic subunit, a serine/threonine kinase | Phosphorylates pRb and drives G1/S transition |
| CDKN1B | Encodes p27Kip1, a CDK inhibitor that can bind to the complex | Modulates complex assembly and activity |
| CDKN1A | Encodes p21Cip1, a CDK inhibitor that interacts with the complex | Influences complex formation in fibroblasts |
| RB1 | Encodes the retinoblastoma protein, a key substrate of the complex | Phosphorylation by cyclin D3-CDK4 releases E2F and promotes S phase |
| CCND1 | Encodes cyclin D1, which forms a related complex with CDK4 | Provides comparative insights into CDK4 substrate specificity |
| CDK6 | Encodes CDK6, a related kinase that can also bind cyclin D3 | Targeted by CDK4/6 inhibitors and stabilized in complexes |
| GSK3B | Encodes GSK3beta, a kinase involved in the GSK3beta-cyclin D3-CUGBP1-eIF2 pathway | Links cyclin D3 to aging and myotonic dystrophy |
| CUGBP1 | Encodes a RNA-binding protein in the GSK3beta-cyclin D3 pathway | Implicated in myotonic dystrophy |
| EIF2 | Encodes eukaryotic translation initiation factor 2, part of the pathway | Connects cyclin D3 to translation regulation in aging |
| TSH | Thyroid-stimulating hormone, not a gene but a regulator | Activates cyclin D3-CDK4-p27Kip1 holoenzyme in thyroid cells |
| TGFB1 | Transforming growth factor beta, a regulator | Inhibits the cyclin D3-CDK4-p27Kip1 holoenzyme |
| PD0332991 | A pharmacological CDK4/6 inhibitor (palbociclib) | Stabilizes activated cyclin D3-CDK4/6 complexes |
| p27Kip1 | Protein product of CDKN1B, a stoichiometric inhibitor | Part of the cyclin D3-CDK4-p27Kip1 holoenzyme |
| p21Cip1 | Protein product of CDKN1A, a stoichiometric inhibitor | Analyzed in cyclin D3-CDK4 complexes in fibroblasts |
| Cyclin D3 | Protein product of CCND3, regulatory subunit | Central to complex formation and cell-cycle progression |
| CDK4 | Protein product of CDK4, catalytic subunit | Phosphorylates pRb and is targeted by inhibitors |
How Is cyclin D3-CDK4 complex Regulated?
The cyclin D3-CDK4 complex is regulated at multiple levels. Its assembly is promoted by mitogenic signals such as TSH in thyroid epithelial cells, while TGFbeta inhibits the holoenzyme. Cyclic AMP-dependent phosphorylation of cyclin D3-bound CDK4 determines passage through the restriction point. Stoichiometric inhibitors p27Kip1 and p21Cip1 can bind to the complex and modulate its activity. Pharmacological CDK4/6 inhibitors such as PD0332991 paradoxically stabilize activated cyclin D3-CDK4/6 complexes, indicating that inhibitor binding can alter complex dynamics. Additionally, the GSK3beta-cyclin D3-CUGBP1-eIF2 pathway links cyclin D3 to aging and myotonic dystrophy, suggesting broader regulatory connections.
cyclin D3-CDK4 complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CCND3 | T-cell leukemia | Knockout or overexpression in T-ALL cell lines |
| CDK4 | Thyroid epithelial cell proliferation | Point mutation of phosphorylation sites in thyroid cells |
| CDKN1B | Cell-cycle regulation in fibroblasts | Knockout of p27Kip1 in fibroblasts |
| RB1 | G1/S transition | Knock-in of phospho-deficient pRb |
| GSK3B | Aging and myotonic dystrophy | Overexpression or knockout in myotonic dystrophy models |
Cyclin D3-CDK4 complex in T-cell leukemia
The cyclin D3:CDK4/6 complex is a therapeutic target in T cell leukemia. Sawai et al. demonstrated that targeting this complex is effective in T cell leukemia models, highlighting its role in leukemogenesis. This suggests that dysregulation of cyclin D3-CDK4 contributes to T cell malignancies and that inhibitors may have clinical utility.
Cyclin D3-CDK4 complex in thyroid epithelial cell proliferation
In thyroid epithelial cells, the cyclin D3-CDK4-p27Kip1 holoenzyme is activated by TSH and inhibited by TGFbeta. Cyclic AMP-dependent phosphorylation of cyclin D3-bound CDK4 determines passage through the restriction point, linking this complex to thyroid cell cycle control. Distinct specificities of pRb phosphorylation by CDK4 activated by cyclin D1 or cyclin D3 further differentiate their roles in thyroid mitogenic modes.
Cyclin D3-CDK4 complex in aging and myotonic dystrophy
The GSK3beta-cyclin D3-CUGBP1-eIF2 pathway connects cyclin D3 to aging and myotonic dystrophy. This pathway suggests that cyclin D3, beyond its role in the cyclin D3-CDK4 complex, participates in signaling cascades relevant to age-related and neuromuscular diseases.
Cyclin D3-CDK4 complex in corpus luteum biology
Levels and interactions of p27, cyclin D3, and CDK4 were studied during the formation and maintenance of the corpus luteum in mice, indicating a role for the complex in reproductive physiology. This extends the relevance of cyclin D3-CDK4 beyond cancer to normal tissue remodeling.
From cyclin D3-CDK4 complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does cyclin D3-CDK4 complex drive T-cell leukemia? | CCND3 knockout in T-ALL cell lines |
| How does p27Kip1 affect complex assembly? | CDKN1B knockout fibroblasts |
| What is the role of CDK4 phosphorylation in restriction point? | Point mutation of CDK4 phosphorylation sites |
| How does pRb phosphorylation specificity differ? | Knock-in of pRb mutants in thyroid cells |
| Does cyclin D3-CDK4 complex respond to CDK4/6 inhibitors? | Overexpression of cyclin D3 and CDK4 in cancer cells treated with PD0332991 |
| What is the role of cyclin D3 in corpus luteum? | Knockout mouse models |
How to Study the cyclin D3-CDK4 complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Co-immunoprecipitation | Protein-protein interactions | Detecting cyclin D3-CDK4 complex assembly |
| Western blotting | Protein levels and modifications | Assessing complex components and phosphorylation |
| Two-dimensional gel electrophoresis | Protein isoforms and post-translational modifications | Analyzing holoenzyme subunit phosphorylations |
| In vitro kinase assay | Catalytic activity | Measuring pRb phosphorylation by cyclin D3-CDK4 |
| CRISPR knockout | Gene function loss | Studying requirement for complex in leukemia |
| CRISPR point mutation | Specific amino acid function | Dissecting CDK4 phosphorylation sites |
| CRISPR knock-in | Tagged or mutant protein expression | Localization and interaction studies |
| Overexpression | Gain-of-function effects | Modeling complex-driven proliferation |
Co-immunoprecipitation and Western Blotting
Co-immunoprecipitation followed by Western blotting is used to detect the physical interaction between cyclin D3 and CDK4. This method was employed to analyze cyclin D3-CDK4 complexes in fibroblasts expressing and lacking p27Kip1 and p21Cip1. It allows assessment of complex assembly and stoichiometry under different conditions.
Two-Dimensional Gel Electrophoresis
Two-dimensional gel electrophoresis was used to demonstrate phosphorylations of subunits in the cyclin D3-CDK4-p27Kip1 holoenzyme in thyroid epithelial cells. This technique resolves protein isoforms and can identify post-translational modifications that regulate complex activity.
Kinase Assays
In vitro kinase assays measure the catalytic activity of the cyclin D3-CDK4 complex toward substrates such as pRb. Such assays have been used to show distinct specificities of pRb phosphorylation by CDK4 activated by cyclin D1 or cyclin D3. They are essential for determining how inhibitors or mutations affect kinase function.
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 is used to generate knockout, point-mutation, knock-in, and overexpression models to study the cyclin D3-CDK4 complex. For example, knockout of CCND3 or CDK4 can reveal their roles in T-cell leukemia and cell-cycle progression. Point mutations can dissect phosphorylation sites, while knock-in of tagged alleles enables localization studies.
How CRISPR Can Be Used to Study GO:0097130 cyclin D3-CDK4 complex
Knockout
CRISPR knockout of CCND3 or CDK4 eliminates the cyclin D3-CDK4 complex, allowing researchers to study its essential functions. For example, knockout of CCND3 in T-cell leukemia models can test whether the complex is required for leukemic cell proliferation. Knockout of CDKN1B (p27Kip1) can also modulate complex assembly and activity.
Point Mutation
Point mutations introduced by CRISPR can dissect the role of specific phosphorylation sites in CDK4 or cyclin D3. For instance, mutation of cyclic AMP-dependent phosphorylation sites in CDK4 can reveal their importance in restriction point passage. Such models help distinguish between phosphorylation-dependent and independent functions.
Knock-in
Knock-in of tagged alleles (e.g., GFP or FLAG) at the endogenous CCND3 or CDK4 loci enables real-time tracking of complex localization and interactions. This approach can be combined with live-cell imaging to study dynamic assembly in response to mitogens. Knock-in of mutant pRb can also clarify substrate specificity.
Overexpression
Overexpression of cyclin D3 and CDK4 using CRISPR activation or lentiviral vectors can model complex-driven proliferation and test sensitivity to CDK4/6 inhibitors such as PD0332991. Overexpression in thyroid epithelial cells can mimic TSH-stimulated states.
How EDITGENE Supports cyclin D3-CDK4 complex Research
Researchers studying cyclin D3-CDK4 complex-related genes often need to determine whether a candidate gene is causally involved in complex assembly, kinase activity, or disease progression. EDITGENE provides a comprehensive suite of CRISPR-based services to enable such investigations with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for cyclin D3-CDK4 complex research.
Frequently Asked Questions About cyclin D3-CDK4 complex
What is the cyclin D3-CDK4 complex?
The cyclin D3-CDK4 complex (GO:0097130) is a protein complex consisting of cyclin D3 and cyclin-dependent kinase 4 (CDK4). It functions as a serine/threonine kinase that phosphorylates the retinoblastoma protein to promote cell-cycle progression.
What genes are involved in the cyclin D3-CDK4 complex?
The core genes are CCND3 (encoding cyclin D3) and CDK4. Regulatory genes include CDKN1B (p27Kip1), CDKN1A (p21Cip1), and RB1, among others.
How is the cyclin D3-CDK4 complex regulated?
It is regulated by mitogenic signals such as TSH, inhibited by TGFbeta, and modulated by phosphorylation of its subunits. Stoichiometric inhibitors p27Kip1 and p21Cip1 can bind to the complex.
What diseases are associated with the cyclin D3-CDK4 complex?
It is implicated in T-cell leukemia, thyroid epithelial cell proliferation, and pathways related to aging and myotonic dystrophy.
What is the function of cyclin D3 in the complex?
Cyclin D3 serves as the regulatory subunit that binds to and activates CDK4, determining substrate specificity and cell-cycle timing.
How do CDK4/6 inhibitors affect the cyclin D3-CDK4 complex?
Inhibitors such as PD0332991 paradoxically stabilize activated cyclin D3-CDK4/6 complexes, which may contribute to their pharmacological effects.
What experimental models are used to study the cyclin D3-CDK4 complex?
Common models include CRISPR knockout, point mutation, knock-in, and overexpression in cell lines such as fibroblasts and thyroid epithelial cells.
What is the role of p27Kip1 in the cyclin D3-CDK4 complex?
p27Kip1 can bind to the complex as part of the holoenzyme, modulating its activity. Its presence affects complex assembly and kinase function.
How does the cyclin D3-CDK4 complex differ from cyclin D1-CDK4?
CDK4 activated by cyclin D1 or cyclin D3 shows distinct specificities for pRb phosphorylation, leading to different mitogenic outcomes.
What methods are used to detect the cyclin D3-CDK4 complex?
Co-immunoprecipitation, Western blotting, two-dimensional gel electrophoresis, and kinase assays are commonly used to detect and characterize the complex.
Conclusion
The cyclin D3-CDK4 complex (GO:0097130) is a critical regulator of the cell cycle, integrating mitogenic signals to drive G1-to-S transition through pRb phosphorylation. Its assembly and activity are finely tuned by stoichiometric inhibitors and post-translational modifications, and its dysregulation is linked to cancers such as T-cell leukemia and other proliferative disorders. Continued research using advanced CRISPR models and biochemical assays will further elucidate its roles and therapeutic potential.
References
- 1. Paternot S et al.. 2014. The CDK4/CDK6 inhibitor PD0332991 paradoxically stabilizes activated cyclin D3-CDK4/6 complexes.. Cell Cycle 13(18):2879-88 PMID: 25486476
- 2. Sawai CM et al.. 2012. Therapeutic targeting of the cyclin D3:CDK4/6 complex in T cell leukemia.. Cancer Cell 22(4):452-65 PMID: 23079656
- 3. Bagui TK et al.. 2000. Analysis of cyclin D3-cdk4 complexes in fibroblasts expressing and lacking p27(kip1) and p21(cip1).. Mol Cell Biol 20(23):8748-57 PMID: 11073976
- 4. Hampl A et al.. 2000. Levels and interactions of p27, cyclin D3, and CDK4 during the formation and maintenance of the corpus luteum in mice.. Biol Reprod 62(5):1393-401 PMID: 10775192
- 5. Paternot S et al.. 2003. Cyclic AMP-dependent phosphorylation of cyclin D3-bound CDK4 determines the passage through the cell cycle restriction point in thyroid epithelial cells.. J Biol Chem 278(29):26533-40 PMID: 12730225
- 6. Coulonval K et al.. 2003. The cyclin D3-CDK4-p27kip1 holoenzyme in thyroid epithelial cells: activation by TSH, inhibition by TGFbeta, and phosphorylations of its subunits demonstrated by two-dimensional gel electrophoresis.. Exp Cell Res 291(1):135-49 PMID: 14597415
- 7. Jin J et al.. 2009. GSK3beta-cyclin D3-CUGBP1-eIF2 pathway in aging and in myotonic dystrophy.. Cell Cycle 8(15):2356-9 PMID: 19571675
- 8. Paternot S et al.. 2006. Distinct specificities of pRb phosphorylation by CDK4 activated by cyclin D1 or cyclin D3: differential involvement in the distinct mitogenic modes of thyroid epithelial cells.. Cell Cycle 5(1):61-70 PMID: 16294008
