CCNI Human, also known as Cyclin I, is a recombinant protein belonging to the conserved cyclin family, which regulates cell cycle progression through interactions with cyclin-dependent kinases (CDKs) . Produced in Escherichia coli, this non-glycosylated polypeptide (44.9 kDa) is widely used in laboratory research to study cell cycle mechanisms, apoptosis, and kinase regulation .
Region | Sequence Details |
---|---|
Cyclin Box | Conserved domain critical for CDK binding . |
His-tag | MGSSHHHHHHSSGLVPRGSHMGSMKFPGPLENQRLSFLLEKA... . |
Cell Cycle Coordination: CCNI exhibits continuous expression throughout the cell cycle, unlike other cyclins with phase-specific abundance .
CDK5 Activation: Binds and activates CDK5, influencing neuronal subcellular localization (nuclear vs. cytoplasmic retention) .
Apoptosis Regulation: Protects podocytes from apoptosis in renal injury models .
Complex | Kinase Activity (Relative to p35-CDK5) | Localization |
---|---|---|
CCNI-CDK5 | Moderate | Nuclear |
CCNI2-CDK5 | Higher than CCNI | Cytoplasmic |
p35-CDK5 | Highest | Plasma membrane |
Kinase Interaction Studies: Used to map CDK5 binding dynamics and substrate phosphorylation .
Disease Models: Applied in glomerulonephritis research to study apoptosis pathways .
Limitations: Restricted to laboratory research; not approved for therapeutic use .
CCNI (Cyclin I) represents a distinct member of the cyclin protein family that was initially identified in the human forebrain cortex. Unlike classical cyclins primarily involved in direct cell cycle regulation through cyclin-dependent kinase activation, CCNI demonstrates broader biological functions including roles in cell proliferation, apoptosis regulation, and angiogenesis .
Key distinguishing characteristics include:
Expression pattern: While most cyclins show oscillating expression during cell cycle progression, CCNI exhibits more stable expression patterns across cellular states
Subcellular localization: CCNI is predominantly localized to the nucleus
Functional diversity: Beyond cell cycle regulation, CCNI has demonstrated roles in apoptosis regulation in specific cell types
For accurate CCNI characterization, researchers should employ multiple complementary methodologies:
Immunohistochemical staining for tissue localization
Western blotting with specific antibodies for protein detection
qPCR for quantitative expression analysis
Fluorescence microscopy for subcellular localization studies
Research has demonstrated that CCNI2 plays a promoting role in colorectal cancer (CRC) progression, with high expression levels correlating with poor patient prognosis . Methodological approaches to study CCNI2 include:
Sequence alignment analysis to identify conserved domains
Phylogenetic analysis to understand evolutionary relationships
Comparative functional studies between CCNI and CCNI2
Expression profiling across tissue types
Knockdown experiments have revealed that downregulation of CCNI2 inhibits CRC cell proliferation and colony formation, arrests cell cycle in G2 phase, and promotes cell apoptosis, suggesting potential as both a prognostic marker and therapeutic target .
When designing experiments to investigate CCNI function, researchers should follow established methodological principles while addressing the specific challenges of CCNI research:
Signal and Noise Consideration:
Experimental design should enhance the signal (CCNI-related variables) while minimizing noise (random influences) . This approach is particularly important given CCNI's multiple functional roles.
Standardized Experimental Framework:
Follow established standards for experiments with human participants
Implement methodologies recognized by relevant professional organizations
Recommended Experimental Approaches:
For in vitro studies:
Cell proliferation assays: MTT assay, colony formation assay
Cell cycle analysis: Fluorescence-activated cell sorting
Expression modulation: siRNA knockdown, CRISPR-Cas9 editing
For in vivo studies:
Mouse models with CCNI/CCNI2 knockdown
Fluorescence imaging for tumor growth monitoring
Appropriate controls, sample size calculations, and statistical analysis plans should be established before experiment initiation to ensure rigorous interpretation of results.
Accurate measurement of CCNI expression in human samples requires careful consideration of multiple methodological factors:
Tissue Sample Considerations:
Sample processing protocols should maintain protein integrity
Consider tissue heterogeneity when interpreting results
Include appropriate reference tissues for comparative analysis
Recommended Measurement Techniques:
Technique | Advantages | Limitations | Best Application |
---|---|---|---|
Immunohistochemistry | Spatial information, works with FFPE samples | Semi-quantitative | Tissue localization studies |
qPCR | High sensitivity, quantitative | RNA only, not protein | Expression screening |
Western Blot | Protein size confirmation | Lower throughput | Protein expression confirmation |
RNA-seq | Comprehensive, detects isoforms | Complex analysis | Transcriptome-wide analysis |
Validation Requirements:
Use multiple detection methods for confirmation
Employ antibodies with validated specificity for CCNI vs. CCNI2
Include appropriate positive and negative controls
Consider clinical variables that may influence expression
When conducting health-related studies involving CCNI, researchers should implement comprehensive assessment methods including focus groups and surveys to understand the broader clinical context, following established protocols for community health needs assessment .
Research has demonstrated significant roles for CCNI family proteins in cancer development and progression, particularly for CCNI2 in colorectal cancer:
Experimental Evidence:
Immunohistochemical staining shows elevated CCNI2 expression in CRC tissues compared to normal tissue
Kaplan-Meier survival analysis reveals that high CCNI2 expression correlates with poor prognosis
Knockdown of CCNI2 inhibits CRC cell proliferation and colony formation
Cell cycle analysis shows CCNI2 knockdown arrests cells in G2 phase
Apoptosis studies demonstrate CCNI2 downregulation promotes cancer cell death
Mouse models confirm CCNI2 knockdown suppresses tumor growth in vivo
Methodological Approaches for Cancer Studies:
Tissue microarrays for high-throughput expression analysis
Patient-derived xenografts for translational relevance
Multi-omics integration to identify regulatory networks
Correlation of expression with clinical outcomes
Based on comprehensive analysis, CCNI2 contributes significantly to CRC progression and could serve as a prognostic marker, suggesting potential therapeutic applications through targeting CCNI-related pathways .
When investigating CCNI in patient samples for clinical correlation, researchers should implement rigorous methodological approaches:
Sample Collection and Processing:
Standardized protocols for tissue collection and preservation
Detailed documentation of clinical variables
Inclusion of matched normal-tumor pairs when possible
Consideration of tumor heterogeneity through multiple sampling
Clinical Correlation Methods:
Kaplan-Meier survival analysis to assess prognostic value
Multivariate Cox regression to identify independent prognostic factors
Stratification by known prognostic factors to identify added value
Integration with established clinical variables
Quality Control Considerations:
Blinded assessment of expression levels
Inclusion of technical and biological replicates
Standardized scoring systems for immunohistochemistry
Independent validation in separate patient cohorts
Researchers should also consider implementing health survey methodologies similar to those used in community health needs assessments, including:
Focus group discussions with clinical experts
Structured surveys on perceived health impacts
Tiered assessment of significance to identify priority areas
Contradictions in CCNI research data present significant challenges requiring structured analytical approaches:
Contradiction Analysis Framework:
Researchers can apply a formalized notation system considering three parameters (α, β, θ):
α: Number of interdependent items
β: Number of contradictory dependencies defined by domain experts
θ: Minimal number of required Boolean rules to assess contradictions
This structured approach helps manage complexity of multidimensional interdependencies within CCNI datasets and supports implementation of generalized contradiction assessment frameworks .
Methodological Strategies:
Systematic literature review with quality assessment
Meta-analysis of compatible datasets
Standardization of experimental protocols across laboratories
Development of common data elements for CCNI research
Biological Factors to Consider:
Cell type-specific effects that may explain apparent contradictions
Context-dependent function (normal vs. disease state)
Interaction with tissue-specific factors
Technical factors including antibody specificity and assay sensitivity
Implementing this structured classification of contradiction checks allows efficient scoping of different contradiction patterns across multiple domains in CCNI research .
While direct neuroimaging of CCNI is not currently established, principles from cognitive neuroimaging research can inform methodological approaches:
Multimodal Imaging Approach:
The Centre for Cognitive Neuroimaging (CCNi) demonstrates that integration of multiple imaging modalities provides comprehensive understanding of brain function . For CCNI studies, researchers might consider:
MRI techniques for structural assessment
Functional imaging to correlate CCNI expression with activity
Multi-modal integration (e.g., EEG-fMRI, TMS-EEG)
Cross-scale, cross-species approaches for translational insight
Advanced Analysis Techniques:
Cutting-edge neuroimaging tools and sophisticated analysis methods
Assessment at multiple levels from regional activity patterns to temporal dynamics
Recognition of both population trends and individual variability
These approaches could help correlate CCNI expression patterns with functional brain regions, potentially illuminating its role in neurological conditions given its original identification in the human forebrain cortex.
Based on functional studies demonstrating CCNI2's role in cancer progression, several therapeutic strategies warrant investigation:
RNA Interference Approaches:
Knockdown experiments have confirmed that reducing CCNI2 expression inhibits cancer cell proliferation, arrests cell cycle progression, and promotes apoptosis in colorectal cancer models . Potential therapeutic applications include:
siRNA delivery systems targeting CCNI2
Antisense oligonucleotides for expression reduction
CRISPR-based therapeutic approaches
Small Molecule Development:
While not specifically mentioned in the search results, traditional drug development approaches could target:
CCNI protein-protein interactions
Enzymatic activities associated with CCNI function
Degradation-promoting compounds (PROTACs)
Combination Therapy Design:
Integration with standard chemotherapies
Synergistic approaches with cell cycle inhibitors
Personalized regimens based on CCNI expression levels
Biomarker-Driven Treatment Selection:
The prognostic value of CCNI2 in colorectal cancer suggests potential use as a companion diagnostic to guide therapy selection .
When developing these approaches, researchers should implement rigorous experimental protocols with appropriate controls and validation studies to ensure target specificity and therapeutic efficacy.
Incorporating CCNI into personalized medicine requires methodological rigor and comprehensive clinical validation:
Patient Stratification Strategy:
Expression profiling of CCNI/CCNI2 in patient samples
Correlation with treatment response and outcomes
Integration with other molecular and clinical biomarkers
Development of predictive algorithms incorporating CCNI status
Implementation Considerations:
Standardized assays for clinical application
Validated cutoff values for classification
Quality control measures
Regulatory pathway development
Clinical Trial Design:
Biomarker-stratified patient selection
Adaptive designs to optimize treatment approaches
Appropriate control groups
Statistical powering for subgroup analyses
Ethical and Practical Factors:
Cost-benefit assessment for clinical implementation
Integration with existing clinical workflows
Patient consent and education protocols
Data privacy protections
The established prognostic value of CCNI2 in colorectal cancer provides a foundation for personalized approaches, potentially enabling more precise risk stratification and treatment selection for cancer patients .
Several cutting-edge technologies offer promising approaches to deepen our understanding of CCNI biology:
Advanced Imaging Technologies:
Super-resolution microscopy for precise subcellular localization
Multiplexed imaging for simultaneous detection of interaction partners
Live-cell imaging for dynamic functional assessment
Digital spatial profiling for tissue microenvironment context
Multi-Omics Integration:
Single-cell transcriptomics to resolve cellular heterogeneity
Spatial transcriptomics to map expression in tissue context
Proteomics for comprehensive interaction mapping
Computational integration across multiple data types
Functional Genomics Approaches:
CRISPR screening to identify synthetic lethal interactions
Base editing for targeted mutagenesis
CRISPRi/CRISPRa for expression modulation
Pooled in vivo screening approaches
Computational Methods:
Machine learning for pattern discovery in complex datasets
Molecular dynamics simulations for structural insights
Network analysis for pathway integration
Predictive modeling for therapeutic response
These technologies could address key knowledge gaps, including tissue-specific interaction partners, structural features distinguishing CCNI from other cyclins, and dynamic changes during disease progression.
Despite significant progress, several fundamental questions about CCNI remain unresolved and should drive future research directions:
Mechanistic Understanding:
What are the specific cyclin-dependent kinases (CDKs) that partner with CCNI?
How does CCNI2 promote cancer progression at the molecular level?
What regulates CCNI/CCNI2 expression in different tissues?
How do post-translational modifications affect CCNI function?
Disease Relevance Beyond Cancer:
What roles does CCNI play in neurological disorders given its brain expression?
Are there CCNI-related functions in inflammatory or metabolic diseases?
Does CCNI contribute to aging-related pathologies?
Can CCNI status predict response to specific therapies?
Evolutionary Context:
How did CCNI function evolve relative to other cyclins?
What explains the functional divergence between CCNI and CCNI2?
Are there species-specific differences in CCNI function?
Translational Applications:
Can CCNI-targeting therapeutics be developed with acceptable safety profiles?
What combination strategies would maximize efficacy of CCNI-targeted treatments?
How can CCNI biomarkers be effectively implemented in clinical practice?
Addressing these questions will require interdisciplinary collaboration across molecular biology, biochemistry, computational biology, clinical research, and drug development fields.
Cyclin-I is composed of 377 amino acids and has a molecular weight of approximately 41.4 kDa . It is expressed consistently during cell cycle progression, unlike other cyclins that exhibit distinct expression and degradation patterns . This consistent expression suggests that Cyclin-I may have unique regulatory roles compared to other cyclins.
Recombinant Cyclin-I is typically produced using Escherichia coli (E. coli) as the expression host . The recombinant protein is often tagged with histidine (His) at both the N-terminal and C-terminal ends to facilitate purification. The protein is usually lyophilized from a sterile PBS solution with added protectants like trehalose, mannitol, and Tween80 .
Recombinant Cyclin-I is used primarily for research purposes. It is valuable in studying cell cycle regulation, protein interactions, and the role of cyclins in various cellular processes. The protein can be used in various assays, including Western blotting, ELISA, and immunoaffinity purification .
Lyophilized recombinant Cyclin-I is stable for up to 12 months when stored at -20°C to -80°C. Once reconstituted, the protein solution can be stored at 4-8°C for 2-7 days or at -20°C for up to 3 months .
Cyclin-I’s consistent expression and unique regulatory roles make it a significant protein for understanding cell cycle dynamics and developing potential therapeutic interventions.