CYR61 Human

What is CYR61 and what are its primary structural characteristics?

CYR61 is a secreted, cysteine-rich, heparin-binding protein encoded by a growth factor-inducible immediate-early gene. It functions as an extracellular, matrix-associated signaling molecule with a molecular weight of approximately 50 kDa . The protein contains specialized domains that enable interactions with multiple integrins including αVβ3, αVβ5, αMβ2, and α6β1, which mediate many of its biological functions . The modular structure of CYR61 facilitates its diverse cellular activities through distinct binding regions and recognition motifs.

What are the established functions of CYR61 in normal human physiology?

In normal physiological conditions, CYR61 regulates several critical cellular processes:

• Promotes adhesion of endothelial cells through interaction with integrin αVβ3

• Augments growth factor-induced DNA synthesis in endothelial cells

• Stimulates directed migration of human microvascular endothelial cells through αVβ3-dependent pathways

• Induces neovascularization as demonstrated in rat cornea models

• Functions as an injury-responsive gene in the liver with protective effects against hepatic fibrosis

• Regulates the growth and adhesion of multiple cell types including vascular endothelial cells, fibroblasts, and monocytes

What methodologies are most effective for detecting and measuring CYR61 in experimental systems?

For reliable quantification of CYR61 in research settings, several validated methods are available:

ELISA-based Detection:
ELISA offers high sensitivity for CYR61 quantification with well-established precision parameters:

Recovery efficiency in various biological matrices:

Other effective methodologies include immunohistochemistry for tissue localization, Western blotting for protein expression analysis, and RT-qPCR for transcriptional studies .

How do we reconcile the apparently contradictory roles of CYR61 in cancer progression?

The dual role of CYR61 in cancer represents a significant research challenge. While early studies identified CYR61 as an angiogenic inducer that promotes tumor growth and vascularization , recent evidence indicates a tumor-suppressive function in liver cancer . These contradictions can be addressed experimentally through:

• Multi-model validation: Employing diverse cell lines and animal models to establish context-dependent functions

• Spatial-temporal analysis: Examining CYR61 function at different stages of cancer development

• Molecular mechanism dissection: Identifying differential binding partners and downstream effectors in various cancer types

• Microenvironmental consideration: Analyzing the impact of tumor microenvironment on CYR61 signaling

For example, in gastric adenocarcinoma models, CYR61 expression enhances tumorigenicity, resulting in larger and more vascularized tumors . Conversely, in hepatocellular carcinoma, CYR61 is significantly downregulated in tumor tissues compared to normal liver, suggesting a protective role .

What is the mechanistic relationship between TGF-β, YAP signaling, and CYR61 expression in liver cancer?

Recent experimental evidence reveals a complex regulatory network:

• TGF-β-activated Smad2/3 coordinates with YAP/TEAD4 to regulate CYR61 promoter activity and transcription in liver cancer cells

• CYR61 can ameliorate both TGF-β- and YAP activation-induced malignant transformation of liver cancer cells in vitro

• CYR61 can inhibit HCC xenograft growth in vivo

To investigate these interactions, researchers should employ:

• Chromatin immunoprecipitation (ChIP) assays to confirm transcription factor binding to the CYR61 promoter

• Luciferase reporter assays to quantify promoter activity under different signaling conditions

• Co-immunoprecipitation to detect protein complexes formed between pathway components

• Gene editing approaches (CRISPR/Cas9) to validate functional relationships

What experimental approaches are most effective for studying CYR61 function in human disease models?

Comprehensive investigation of CYR61 function requires multi-level experimental design:

• Genetic Manipulation Approaches:

  • CRISPR/Cas9 gene knockout systems (available as research kits)

  • Inducible expression systems for time-controlled overexpression

  • Domain-specific mutations to identify functional regions

• In vivo Models:

  • Xenograft models with manipulated CYR61 expression

  • Patient-derived xenografts to maintain tumor heterogeneity

  • Humanized mouse models to better recapitulate human biology

• Mechanistic Analysis:

  • Integrin blocking experiments to identify receptor dependencies

  • Proteomic analysis to identify interaction partners

  • Phosphorylation studies to elucidate downstream signaling events

What are critical controls and variables to consider when designing CYR61 functional studies?

When designing experiments to study CYR61 function, researchers should implement:

• Essential Controls:

  • Isotype antibody controls for neutralization experiments

  • Empty vector controls for expression studies

  • Scrambled CRISPR controls for knockout studies

  • Multiple cell lines to account for tissue-specific effects

• Critical Variables:

  • Integrin expression profile of the experimental system

  • Matrix composition, as CYR61 is matrix-associated

  • Concentration dependence, as effects may vary with protein level

  • Temporal considerations, particularly for immediate-early gene responses

• Validation Approaches:

  • Complementary gain- and loss-of-function studies

  • Multiple detection methods for expression analysis

  • Both in vitro and in vivo validation

How should researchers interpret CYR61 expression changes in clinical samples?

Proper interpretation of CYR61 expression requires several considerations:

• Technical Factors:

  • Sample collection and processing protocols can affect CYR61 detection

  • Proper normalization for quantitative comparisons

  • Distinction between total and active/available CYR61

• Biological Context:

  • Cell type-specific expression patterns

  • Disease stage and progression status

  • Correlation with patient clinical parameters

  • Relationship to other signaling molecules (e.g., TGF-β, YAP)

• Clinical Significance Assessment:

  • Longitudinal analysis to determine prognostic value

  • Comparison across different disease subtypes

  • Multivariate analysis with established biomarkers

In HCC studies, for example, CYR61 downregulation in tumor tissues compared to normal liver predicted worse clinical outcomes, suggesting its potential value as a prognostic marker .

What technical challenges exist in studying CYR61 post-translational modifications and processing?

CYR61 undergoes several modifications that influence its function:

• Proteolytic Processing:

  • Cleavage by plasmin within the VWF domain generates an N-terminal fragment that retains migration-inducing ability but loses matrix association

  • Methodologies should include size analysis to detect processed forms

• Glycosylation Analysis:

  • As a glycoprotein, CYR61 function may be modulated by glycosylation state

  • Glycosidase treatments and glycoprotein-specific staining can reveal modification patterns

• Secretion vs. Intracellular Pools:

  • Distinguishing between secreted and cell-associated CYR61 requires careful fractionation

  • Pulse-chase experiments can track protein trafficking and secretion dynamics

What emerging technologies hold promise for advancing CYR61 research?

Several cutting-edge approaches are poised to enhance our understanding of CYR61 biology:

• Single-cell Analysis:

  • Single-cell RNA sequencing to resolve heterogeneous expression patterns

  • Single-cell proteomics to identify cell-specific signaling networks

• Advanced Imaging:

  • Super-resolution microscopy to visualize CYR61-integrin interactions

  • Intravital imaging to track CYR61 function in live animal models

• Systems Biology:

  • Multi-omics integration to place CYR61 within broader signaling networks

  • Computational modeling to predict context-dependent functions

What are the most promising translational applications of CYR61 research?

Based on current understanding, several translational directions warrant investigation:

• Diagnostic Applications:

  • Development of CYR61-based biomarkers for cancer prognosis

  • Tissue-specific expression patterns as diagnostic indicators

• Therapeutic Strategies:

  • Recombinant CYR61 administration for contexts requiring its beneficial effects

  • Targeting CYR61-integrin interactions in disease-specific contexts

  • Modulation of TGF-β and YAP pathways to regulate CYR61 expression

• Regenerative Medicine:

  • Leveraging CYR61's role in wound healing and tissue repair

  • Engineering scaffolds incorporating CYR61 for improved tissue regeneration

What are the specific biochemical parameters of human CYR61 protein?

Human CYR61/CCN1 has the following biochemical characteristics:

• Molecular weight: 50 kDa

• Gene ID: 3491

• UniProt ID: O00622

• Synonyms: CCN1, GIG1, IGFBP10

• Primary binding partners: Integrins αVβ3, αVβ5, αMβ2, and α6β1; heparan sulfate proteoglycan

• Structure: Secreted, cysteine-rich, heparin-binding glycoprotein

What reference ranges should be considered when measuring CYR61 in human samples?

Based on ELISA validation studies, the following reference parameters have been established:

• Detectable Range: Typically in pg/mL range (standard curve optimization required)

• Normal Variation: CV% typically between 2.0-6.4% depending on sample type

• Sample Type Considerations: Measurements show consistent recovery across cell culture media (98-117%), plasma (91-104%), and serum (95-113%)