Cell Adhesion

Question 1

Functions of cell-to-cell interactions

Answer 1

1. Wound healing
2. Inflammation response
3. Immune response (self vs. non-self recognition)
4. Tumor metastasis
5. Blood clotting
6. Growth and development

Question 2

Cell adherence is?

Answer 2

Specific and reversible

Question 3

2 types of cell adherence

Answer 3

1. Homotypic adhesion

2. Heterotypic adhesion

Question 4

Cell-cell interactions are dependent on?

Answer 4

1. Cell-cell recognition

2. Cell-cell adhesion → allows for communication

Question 5

Cadherins need ____ to function, which is to:

Answer 5

Require calcium

Allow interaction with neighboring cell via cadherins of same time

Question 6

Cadherin adhesion

Answer 6

Homotypic adhesion → bind through adherens junctions (actin cytoskeleton, desmosomes)

Question 7

Integrins are?

Answer 7

Linker proteins (link ECM components and cell)

Question 8

Types of cell junctions

Answer 8

1. Adhesive (anchoring)
2. Tight
3. Gap

Question 9

Adhesive (anchoring) junctions

Answer 9

Links cells in tissues by connecting cytoskeletons → allows cells to function as unit and share stress

Question 10

Adhesive junctions are prominent in?

Answer 10

Cells subjected to high stress;

1. Skin
2. Bladder
3. Heart
4. Stomach

Question 11

Adhesive junction types

Answer 11

1. Desmosomes
2. Hemidesmosomes
3. Adherens junction

Question 12

All adhesive junctions contain 2 distinct types of proteins. What are they?

Answer 12

1. Intracellular attachment proteins (inside plasma membrane)
2. Transmembrane linker proteins (outside plasma membrane → bind cells to ECM)

Question 13

Desmosome adhesion

Answer 13

Between cells (linker proteins)

Provides structural integrity (resists stress)

Question 14

Desmosomes are in what kind of cells?

Answer 14

Squamous epithelial and muscle cells

Question 15

Desmosomes are abundant in what types of tissues?

Answer 15

1. Heart
2. Skin
3. Neck of uterus

Question 16

Hemidesmosomes connect

Answer 16

Epithelial cell to basal membrane (plaque only in 1 cell)

Question 17

2 types of adhesive junctions

Answer 17

1. Adhesion belt

2. Focal contact

Question 18

Adhesion belts

Are:

Common in:

Connection:

Answer 18

Encompass entire cell

Common in layer of tissue that line body cavities

Connect to cytoskeleton and adjacent cell via actin

Question 19

Focal contact

Answer 19

Attach cells to ECM

Not continuous

Use integrins

Question 20

What are connexons?

Answer 20

Hollow cylinders → special type of protein composed of assembly of 6 connexin subunits

Question 21

Gap junctions are abundant in tissue with what requirements?

Answer 21

Rapid communication (muscle and nerve)

Question 22

What do gap junctions facilitate in the heart?

Answer 22

Flow of electrical current

Question 23

Where are gap junctions in the brain?

Answer 23

Cerebellum → facilitates rapid muscle movements

Question 24

Tight junctions

Answer 24

Leave NO space between plasma membranes of adjacent cells → prevents movement of fluids and ions between cells (or of 2 different body compartments)

Question 25

Tight junction with the least amount of sealing are found where?

Answer 25

Bladder

Question 26

Tightest tight junctions in the body

Answer 26

Epithelial cells of inner ear

Question 27

Function of blood-brain barrier derives largely from?

Answer 27

Tight junctions

Question 28

How is the efficiency of a tight junction regulated?

Answer 28

Number of independent sealing strands

Question 29

Major proteins in sealing strands of tight junctions

Answer 29

Claudins and occuludin

Question 30

What are sealing strands in tight junctions formed from?

Answer 30

Row of transmembrane proteins embedded in both plasma membranes Extracellular domains join one another directly

Question 31

Tight junctions joint together the ______ of adjacent cells

Answer 31

Cytoskeleton

Question 32

Pemphigus

Answer 32

Autoimmune disorder which produces antibodies against cadherins Skin gets attached by immue system and looks fucked up (lots of blisters and such)

Question 33

Natalizumab

Answer 33

Anti-integrin antibodies (attached alpha 4-integrin) | Used to treat MS (multiple sclerosis) and IBD (inflammatory bowel disease)

Question 34

Cadherins do what type of cell adhesion?

Answer 34

Homotypic (especially epithelia)

Question 35

Cadherins bind through

Answer 35

Adherens junction: actin cytoskeleton + desmosomes

Question 36

Desmogelins

Answer 36

Type of cadherin, targeted by pemphigus

Question 37

Most common immune mediated skin disease in dog and cat

Answer 37

Pemphigus foliaceus

Question 38

alpha 4-integrins

Answer 38

Important for recruitment of lymphocytes ad monocytes to inflammation sites

Question 39

Homotypic adhesion

Answer 39

Adherence of cell to similar cell | Ex: epithelial cells in epithelial sheet

Question 40

Heterotypic adhesion

Answer 40

Adherence of cell to dissimilar cell | Ex: neuron + Schwann cell, neutrophil + endothelial cell

Question 41

Cadherin location

Answer 41

Plasma membrane of most cells

Question 42

Cadherin side chains

Answer 42

Carbohydrate side chains (affect strength and specificity)

Question 43

Intracellular attachment proteins

Answer 43

Attach adhesive junction to cytoskeleton filaments (inside plasma membrane)

Question 44

How do intracellular attachment proteins attach adhesive junction to cytoskeleton filaments?

Answer 44

Form thick plaque on cytoplasmic side of plasma membrane

Question 45

How do connexins form gap junctions?

Answer 45

2 hemichannels/connexins from opposing cells stick together to form intercellular gap junction channel

Question 46

Why are integrins "linker" and no "adhesive" proteins?

Answer 46

Weak binding → low affinity allows for exploration of environment → prevents "gluing" of cell to ECM