Cell Adhesion and Signalling Quiz

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of cell adhesion in multicellular organisms?

  • Waste elimination
  • Nutrient absorption
  • Tissue formation (correct)
  • Metabolic processes

Leukocytes binding to endothelial cells is an example of firm adhesion.

False (B)

Name one function of tight junctions.

Conferring impermeability

____________ are cell adhesion molecules that link to the actin cytoskeleton in adherens junctions.

<p>Cadherins</p> Signup and view all the answers

Match the cell adhesion molecule with its function:

<p>Cadherins = Cell-cell adhesion Integrins = Cell-matrix adhesion Selectins = Non-junctional adhesion Ig family members = Signalling junctions</p> Signup and view all the answers

Which type of junction allows passage of small molecules and ions between cells?

<p>Gap junctions (B)</p> Signup and view all the answers

Cell adhesion molecules play no role in signaling between cells.

<p>False (B)</p> Signup and view all the answers

What is the role of integrins in cell adhesion?

<p>Linking cells to the extracellular matrix</p> Signup and view all the answers

Transient cellular adhesions include the attachment of ________ to endothelial cells.

<p>leukocytes</p> Signup and view all the answers

Which of the following types of junctions provides structural support while allowing signal transduction?

<p>Gap junctions (A)</p> Signup and view all the answers

What is the primary role of selectins in response to inflammation?

<p>Cell adhesion and aggregation (B)</p> Signup and view all the answers

E-selectin is downregulated during inflammatory responses.

<p>False (B)</p> Signup and view all the answers

What are hemidesmosomes primarily responsible for?

<p>Linking epithelial cells to the basement membrane</p> Signup and view all the answers

Selectins promote _____ aggregation.

<p>platelet</p> Signup and view all the answers

Which integrin is specialized in linking epithelial cells to the basement membrane?

<p>α6β4 (C)</p> Signup and view all the answers

Syndecans are responsible for mediating cell adhesion to extracellular matrix.

<p>True (A)</p> Signup and view all the answers

Name one type of cell that expresses syndecans.

<p>Fibroblasts or epithelial cells</p> Signup and view all the answers

Integrins are composed of non-covalently bound _____ molecules.

<p>heterodimers</p> Signup and view all the answers

Match the following terms with their functions:

<p>Selectins = Promote platelet aggregation Integrins = Link cells to the ECM Syndecans = Mediate cell adhesion to ECM Hemidesmosomes = Anchor epithelial cells to basement membrane</p> Signup and view all the answers

What are the signalling roles of cytokines like TNFα in inflammation?

<p>They regulate selectin expression and promote adhesion of immune cells.</p> Signup and view all the answers

What type of adhesion molecules are cadherins?

<p>Ca2+ dependent adhesion molecules (C)</p> Signup and view all the answers

Selectins are expressed on white blood cells, platelets, and endothelial cells.

<p>True (A)</p> Signup and view all the answers

What is the central role of catenins in relation to cadherins?

<p>Catenins link classical cadherins to the actin cytoskeleton.</p> Signup and view all the answers

The __________ domain of cadherins is required for linking to the actin cytoskeleton.

<p>cytoplasmic</p> Signup and view all the answers

Match the following adhesion molecule families with their characteristics:

<p>Cadherins = Ca2+ dependent, homophilic adhesion Selectins = Bind carbohydrates, Ca2+ dependent Immunoglobulin superfamily = Ca2+ independent, can be homophilic or heterophilic Integrins = Link cells to the extracellular matrix</p> Signup and view all the answers

Which molecules mediate the rolling of leukocytes on endothelial cells?

<p>Selectins (C)</p> Signup and view all the answers

Cadherins provide a strong attachment due to their individual high affinity.

<p>False (B)</p> Signup and view all the answers

What do gap junctions primarily allow for?

<p>Small molecule transfer between adjacent cells.</p> Signup and view all the answers

The T cell receptor is an example of an __________ family adhesion molecule.

<p>Immunoglobulin</p> Signup and view all the answers

Match the following cells with their corresponding selectins:

<p>L-selectin = White blood cells P-selectin = Platelets E-selectin = Endothelial cells</p> Signup and view all the answers

What happens to the integrin dimer in the absence of ligand?

<p>It adopts a folded structure (B)</p> Signup and view all the answers

Inside-Out signaling involves the binding of ligands to integrins.

<p>False (B)</p> Signup and view all the answers

What protein competes for binding to the cytoplasmic tails of integrins during Inside-Out signaling?

<p>talin</p> Signup and view all the answers

In Outside-In signaling, ligand binding results in the integrin dimer assuming an ______ conformation.

<p>extended</p> Signup and view all the answers

Match the following concepts with their descriptions:

<p>Focal adhesions = Integrin-based cell-matrix adhesion in motile cells Podosomes = Structures involved in the degradation of the extracellular matrix Talins = Proteins that activate integrins in response to intracellular signals Cytoplasmic tails = Sites of interaction for signaling proteins in integrins</p> Signup and view all the answers

What role does PIP2 play in Inside-Out signaling?

<p>It activates talin (D)</p> Signup and view all the answers

The cytoplasmic tails of integrins remain unchanged during activation.

<p>False (B)</p> Signup and view all the answers

What structure is formed between integrins and F-actin in motile cells?

<p>focal adhesions</p> Signup and view all the answers

During integrin activation, the extracellular portion adopts a higher affinity for ______.

<p>ligand</p> Signup and view all the answers

What are the consequences of integrin activation on its cytoplasmic tails?

<p>They become exposed for cytoskeleton attachment. (B)</p> Signup and view all the answers

Flashcards

Extracellular Matrix (ECM)

The non-cellular material surrounding cells, providing structural support and anchoring for cells

Cell Adhesion

The process by which cells stick to each other and to the extracellular matrix (ECM), crucial for tissue formation and function.

Cell Junctions

Specialized structures where cells connect physically, enabling communication and holding tissues together.

Cadherins

A family of cell adhesion molecules that mediate cell-cell adhesion, connecting to the cytoskeleton.

Signup and view all the flashcards

Integrins

Cell adhesion molecules (CAMs) that mediate cell binding with ECM components, tying to the cytoskeleton.

Signup and view all the flashcards

Tight Junctions

Cell junctions that seal gaps between cells, preventing substances from passing between them.

Signup and view all the flashcards

Desmosomes

Cell junctions that provide strong structural connections between cells, linking to intermediate filaments.

Signup and view all the flashcards

Gap Junctions

Cell junctions that allow small molecules and ions to pass between cells, enabling communication.

Signup and view all the flashcards

Selectins

Cell adhesion molecules (CAMs) involved in transient cell-cell adhesions, especially in immune responses.

Signup and view all the flashcards

Cell-matrix adhesions

Attachments between cells and the extracellular matrix (ECM), typically mediated by integrins.

Signup and view all the flashcards

Immunoglobulin Superfamily

Cell adhesion molecules with immunoglobulin-like domains, mediating calcium-independent adhesion.

Signup and view all the flashcards

Cell-cell adhesion in synapses

Multiple adhesion molecules are needed for proper synapse formation and maintenance for neuronal signaling.

Signup and view all the flashcards

Cell-surface carbohydrate binding proteins

Proteins that bind to carbohydrate molecules on cell surfaces.

Signup and view all the flashcards

Leukocyte rolling

Neutrophils moving along the walls of blood vessels using selectins.

Signup and view all the flashcards

Artery function

Carries blood away from the heart.

Signup and view all the flashcards

Vein function

Carries blood to the heart.

Signup and view all the flashcards

Selectin role

Inflammation-regulated cell adhesion molecules (e.g. E-selectin for neutrophils, P-selectin for platelets).

Signup and view all the flashcards

Syndecan function

Cell surface molecules mediating cell adhesion to extracellular matrix (ECM) and binding growth factors.

Signup and view all the flashcards

Desmosome role

Anchoring junction linking/strengthening epithelial cells.

Signup and view all the flashcards

Hemidesmosome role

Anchoring junction connecting epithelial cells to basement membrane (ECM).

Signup and view all the flashcards

Integrin function

Adhesion molecules linking cells to ECM and cytoskeleton.

Signup and view all the flashcards

Integrin type for Hemidesmosome

Specialized integrin (α6β4) links epithelial cells to basement membrane.

Signup and view all the flashcards

Tissue

A group of similar cells that perform a specific function.

Signup and view all the flashcards

Integrin structure

Integrins are transmembrane proteins composed of two subunits, alpha and beta, which associate to form a heterodimer. These subunits have extracellular, transmembrane, and cytoplasmic domains.

Signup and view all the flashcards

Integrin activation: Outside-In

In the absence of a ligand, integrins are folded. Ligand binding triggers a conformational change, extending the dimer and exposing binding sites for cytoskeletal attachment.

Signup and view all the flashcards

Integrin activation: Inside-Out

Intracellular signaling pathways, such as those involving PIP2, can activate talin. Talin binds to integrin cytoplasmic tails, pushing the subunits apart and extending the extracellular domain, increasing ligand affinity.

Signup and view all the flashcards

Integrin pairs

Different combinations of alpha and beta subunits form various integrin pairs, each with specific binding affinities for different ECM molecules.

Signup and view all the flashcards

Focal Adhesions

These are large, complex protein assemblies that connect the actin cytoskeleton of cells to the extracellular matrix, mediated by integrins.

Signup and view all the flashcards

Podosomes

These are small, dynamic, actin-rich structures found in motile cells, characterized by integrin-mediated adhesion to matrix components.

Signup and view all the flashcards

Vinculin

A protein involved in focal adhesions, linking integrins to the actin cytoskeleton, contributing to adhesion strength and cell migration.

Signup and view all the flashcards

Cell-matrix adhesion in motile cells

Integrins play a crucial role in cell motility, allowing cells to adhere to and move across the ECM. Focal adhesions and podosomes are key structures involved in this process.

Signup and view all the flashcards

ECM binding

Integrins bind to a variety of ECM molecules, including collagen, fibronectin, and laminin, regulating cell adhesion, migration, and signaling.

Signup and view all the flashcards

Cell signaling

Integrin binding to ECM components can activate intracellular signaling pathways, influencing cell growth, differentiation, and survival.

Signup and view all the flashcards

Study Notes

Cell Adhesion and Cell Signalling

  • Multicellular organisms depend on cell adhesion to each other and the extracellular matrix (ECM) for tissue formation.
  • Some adhesive interactions are stable, such as the firm adhesion of muscle cells to each other and connective tissues in tendons. Other adhesive interactions are transient, such as leukocytes binding to endothelial cells to prepare for extravasation into tissues.

Cellular Adhesion

  • Some examples of stable cell-cell adhesive interactions involve muscle cells connecting to each other and connective tissues for transmitting force from skeletal muscles.

  • Examples of transient cell-cell adhesive interactions are those involving leukocytes binding to endothelial cells lining blood vessels as a preparation for extravasation into surrounding tissue. Cells also attach to ECM during cell migration.

Cell Junctions

  • Cell junctions include anchoring junctions, occluding junctions, channel-forming junctions, and signal-relaying junctions.

  • Anchoring junctions (e.g., adherens junctions and desmosomes) connect actin-linked or hemidesmosomes to the cytoskeleton and help transmit physical forces.

  • Occluding junctions (tight junctions) seal gaps between epithelial cells to provide impermeability or selective permeability.

  • Channel-forming junctions (gap junctions) allow passage of small molecules and ions between cell cytoplasms, such as neurons or immune synapses.

  • Signal-relaying junctions allow signal transduction between cells through cell-cell contact sites such as synapses.

  • Cell-cell junctions include those containing classical cadherins (eg E-cadherin), as well as nonclassical cadherins (eg desmoglein) or Ig-like family members (eg NCAM).

Cadherins

  • Cadherins are a family of adhesion proteins that mediate calcium-dependent homophilic adhesion.

  • Cadherin adhesions individually have low affinity but in combination, they provide strong attachment.

  • Different types of cadherins exist, including classical, fat-like, seven-pass transmembrane, protein kinase, desmosomal, cadherin 23 and protocadherins.

Cell Segregation during Embryonic Development

  • Cell segregation during embryonic development is an example of cells expressing different cadherins.
  • For example, cells expressing E-cadherin differentiate to form the neural tube, whilst cells expressing N-cadherin differentiate to form neural crest cells.

Catenins

  • Catenins link classical cadherins to the actin cytoskeleton.
  • Extracellular domains of cadherins link together to mediate adhesion
  • Cytoplasmic domains are required for linking to the actin cytoskeleton, indirectly via anchor proteins, including catenins (β-catenin also functions in signaling, such as the Wnt pathway)

Gap Junctions

  • Gap junctions allow passage of small molecules (ions and molecules like sugars, amino acids, nucleotides and vitamins). and intracellular signaling molecules such as cyclic AMP and inositol trisphosphate between cells.
  • Two types of gap junctions exist: Large and small.

Small Molecule Transfer

  • Gap junctions allow transfer of small molecules, including inorganic ions, sugars, amino acids, nucleotides, vitamins, cyclic AMP and inositol trisphosphate, between cells.

Tight Junctions

  • Tight junctions seal epithelial cells together, preventing the passage of materials between them.
  • The sealing strands of occludin and claudin proteins form a tight junction.

Selectins

  • Selectins mediate transient, weak interactions.
  • Selectins are cell surface carbohydrate-binding proteins that bind to mucins (addressins) on cell surfaces.
  • These interactions help move cells through blood vessels.
  • Selectins are expressed on white blood cells, platelets and endothelial cells (L, E, and P selectins)

Cell Adhesion Molecules and T Cell Recruitment to Lymph Nodes

  • Lymphocytes bind to vascular endothelium (in lymph nodes) via the interaction between L-selectin and vascular addressins.

Cell Adhesion Molecules and Neutrophil Recruitment

  • Selectin-mediated adhesion is weak, allowing neutrophils to roll along vascular endothelial cells.

  • Interactions between selectins and carbohydrate ligands on neutrophils allow their temporary attachment to blood vessel walls.

  • These transient interactions slow down cell movement along the blood vessel wall.

Selectins Regulation

  • Selectins are regulated by inflammatory mediators (e.g., TNFα, CXCL8, leukotriene LTB4, histamine, thrombin.)
  • These inflammatory mediators can upregulate the expression of selectins, increase cell surface expression of selectins on platelets, and promote platelet aggregation.

Syndecans

  • Syndecans are cell surface proteoglycans that mediate cell adhesion to the extracellular matrix (ECM).
  • They bind growth factors like FGF, cytokines and other growth factors.

Desmosomes

  • Desmosomes are cell-cell adhesion structures found in tissues subjected to mechanical stress.
  • They are composed of cadherin-like proteins.
  • Desmosomes connect intermediate filaments of the cytoskeleton between the cells.

Integrins

  • Integrins mediate cell-matrix and cell-cell adhesion.
  • Integrins are non-covalently bound heterodimers.
  • Integrins mediate adhesion of cells to the extracellular matrix.
  • Integrins physically link intracellular cytoskeletons to the extracellular matrix to attach epithelial cells to basal lamina.

Integrin Activation

  • Integrin activation can be either inside-out or outside-in signalling, depending on whether the signal is from inside or outside the cell.
  • Inside-out signalling involves intracellular signalling pathways.
  • Outside-in signalling involves ligand binding at the extracellular receptor site.

Integrin based cell-matrix adhesion in motile cells

  • Focal adhesions and podosomes are examples of integrin-based cell-matrix adhesions involved in motile cells.
  • Focal adhesions are found in many cell types.
  • Podosomes are restricted to specialized cells.
  • These features are important for cell spreading, motility and matrix remodelling.

Integrins in Cell-Cell Adhesion

  • Integrins can bind other cellular adhesion molecules.
  • This is seen in T cell binding to ICAM molecules on antigen presenting cells.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

More Like This

Cell Adhesion and Signalling Quiz
42 questions
Cell Adhesion and Signalling Quiz
40 questions
Cell Adhesion and Signalling Quiz
41 questions
Use Quizgecko on...
Browser
Browser