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Richard O. Hynes
- Affiliation: Massachusetts Institute of Technology
Erkki Ruoslahti
- Affiliation: Sanford Burnham Prebys
Timothy A. Springer
- Affiliation: Boston Children's Hospital/Harvard Medical School
Significance: Recognized for discoveries concerning integrins, which are key mediators of cell-matrix and cell-cell adhesion in physiology and disease.

Absence in Prokaryotes and Simple Organisms:
- Integrins are not found in prokaryotes (e.g., bacteria), plants, or fungi.
Expansion in Vertebrates:
  - Vertebrates have significantly expanded the integrin family to include:
    - 18 alpha subunits
    - 8 beta subunits
Caenorhabditis elegans:
- Has two alpha subunits and one beta subunit that form two integrins.

Total of 24 heterodimers formed from the combination of alpha and beta subunits.
Recognition:
- These integrins recognize immunoglobulin (IG) superfamily counter-receptors and extracellular matrix (ECM) molecules.
Alternative Splicing:
- Contributes to the diversity of integrin receptors.

Type: Type I transmembrane proteins.
Connection: Most integrins are connected via intracellular anchor proteins to actin, with the exception of α6β4, which connects to intermediate filaments.
Characteristics:
  - Molecular Weight: 90-160 kDa.
  - Furin cleavage at the C-terminus and N-terminus.
  - Required ions: Ca2+ and Mg2+.

Common Ligands Include:
- Fibronectin, fibrinogen, collagens, vitronectin, thrombospondin, tenascin, laminin, fibrillin, fibulin, entactin, matrix Gla protein (MAGP), SIBLING proteins, among others.
Key Amino Acids in Binding:
- Often involve either D (Asp, aspartic acid) or E (Glu, glutamic acid) residues, specifically the Arginine-Glycine-Aspartic acid (RGD) sequence.

Study Reference: Xiong et al., Science 296, 151-155.
Structure: Alpha head domain and beta head domain; requires Ca2+ for function.
Ligands: Some integrin ligands contain accessory or 'synergy sites' to enhance binding affinity.
- Example: Fibronectin is the best-characterized ligand, with unique functional domains.

Key Integrin: αIIbβ3 integrin mediates blood platelet aggregation via binding to fibrinogen.
Activation Process:
- Exposure to Collagen IV and/or Thrombin triggers activation.
- Activated integrin αIIbβ3 then binds fibrinogen inducing blood clot formation.
Pathology:
- Glanzmann thrombasthenia is a bleeding disorder caused by mutations in beta3 integrins.

Process Overview:
  - Unbound integrins (α/β dimers) are generally inactive and diffuse freely in plasma membrane.
  - Activation can occur from:
    - "Outside-in" Activation: Binding of an extracellular ligand.
    - "Inside-out" Activation: Signaling from the cytoplasmic tail of the integrin, important for cell aggregation and cell-cell adhesion processes, especially during inflammation.
Activation Steps:
- Weak Binding: Initial weak interaction leads to a conformational change in alpha and beta chains.
- Stronger Binding: Extracellular ligand binding becomes stronger after conformational change, allowing for functionally active integrin.

Key Protein: Talin (270 kDa).
Process Elements:
- Interaction with phosphoinositol-4,5-bisphosphate (PI4,5P-2), a lipid in the plasma membrane.
- After binding, talin disrupts ionic interactions in the inactive state, causing separation of alpha and beta subunits to activate integrin.

Function:
- Disintegrins are proteins that compete with natural ligands for integrin binding, thereby blocking integrin αIIbβ3-fibrin interaction and αvβ3-matrix protein interactions.
Source: These proteins are a large group derived from snake (viper) venom, known for their high homology and presence of cysteine residues and RGD sequences.
Examples: Eristostatin, Echistatin, Kistrin.

Characteristics:
- Integrins are characterized by low affinity but high avidity for their ligands.
- Ligand binding promotes lateral diffusion and redistribution of integrins into focal complexes, leading to clustering.

Study Reference: Mao et al., Matrix Biol. 24:389-399.
Integrin Role:
- α5β1 integrin interacts with actin filaments and assists in the assembly of fibronectin networks.
Associated Proteins: Focal adhesion kinase, vinculin, and paxillin contribute to this assembly process.

The Albert Lasker Award for Basic Medical Research is one of the most prestigious awards in the field of medical research, recognizing pioneering contributions that have advanced our understanding of fundamental biological mechanisms influencing health and disease. Established in 1945, the award emphasizes the importance of research in improving human health and has been a precursor to numerous Nobel Prize winners.

Richard O. Hynes
- Affiliation: Massachusetts Institute of Technology
- Contributions: Noted for his work in revealing the functions and mechanisms of integrins, which play critical roles in cell adhesion and communication.
Erkki Ruoslahti
- Affiliation: Sanford Burnham Prebys
- Contributions: Recognized for his pioneering research on cell adhesion molecules and their implications in cancer metastasis and tissue development.
Timothy A. Springer
- Affiliation: Boston Children's Hospital/Harvard Medical School
- Contributions: Celebrated for his identification of integrins and their receptor roles which have profound implications in various physiological processes including immune response and inflammation.
Significance: The 2022 award highlights the importance of integrins in promoting cell-matrix and cell-cell adhesion, vital for maintaining the structure of tissues and influencing cellular behavior during development, immunity, and disease.