Cell Adhesion Flashcards
1
Q
What do cell-cell interactions promote?
A
- wound healing
- inflammation responses
- immune responses (recognition of self vs. non-self)
- tumor metastasis
- blood clotting
- growth and development
2
Q
Cell adherence is very _____ and ______
A
specific and reveresible
3
Q
Homotypic Adhesion
A
adherence of a cell to a similar cell
ex - epithelieal cells in an epithelial sheet
4
Q
Heterotypic Adhesion
A
adherence of a cell to a dissimilar cell
ex - Neuron and Schwann Cell; Neutrophil and Endothelial Cell
5
Q
Cadherins
A
- Found in Plasma Membrane in Most Animal Cells
- Discovered via Antibody Approach
- Require Calcium to function
- Have carbohydrate side chains that affect strength and specificity
- Homotypic Cell Adhesion
- Bind Through Adherens Junctions
6
Q
Integrins
A
- Linker Proteins that link ECM components and cells
- binding is weak
- low affinity prevents “gluing” of cell to ECM
7
Q
Types of Cell Junctions
A
- Adhesive (Anchoring) = includes desmosomes, hemidesmosomes, and adherens junctions
- tight junctions
- gap junctions
8
Q
Adhesive (Anchoring) Junctions
A
- Link cells in tissues
- connects cytoskeleton to cytoskeleton
- allows cells to function as a unit
- transfers stress between and within cells
- prominent in cells subject to high stress such as skin, bladder, heart, stomach
9
Q
The 3 types of Adhesive Junctions all contain….
A
- 2 distinct types of proteins
- intracellular attachment proteins
- transmembrane linker proteins
10
Q
Intracellular Attachment Proteins
A
- found in Adhesive Junctions
- adhesive junction to cytoskeleton filaments inside a plasma membrane
- form thick plaque on cytoplasmic side of PM
11
Q
Transmembrane Linker Proteins
A
- found in Adhesive Junctions
- outside plasma membrane
- bind cells to ECM
12
Q
Desmosomes
A
- Type of Adhesive junction
- between cells
- provides structural integrity to resist stress
- found in epithelial cells (simple and stratified squamous) and muscle cells
- abundant in heart, skin, and the neck of the uterus
13
Q
Hemidesmosomes
A
- connect epithelial cells to basal membrane
- plaque is only in one cell
14
Q
Adhesive Junctions
A
- 2 Types = adhesion belt and focal contact
- Adhesion belt encompasses entire cell and is common in layers of tissue that line body cavities. also connects to cytoskeleton and adjacent cells via actin
- Focal Contact attaches cells to ECM, is not continuous, and uses integrins
15
Q
Gap Junction
A
- channel formed by connexons that consist of six connexins
- mediate reciprocal exchange of ions and smal molecules
16
Q
Tight Junctions
A
- barrier to passage of both ions and molecules through paracellular pathway
- Leaves NO space between PM of adjacent cells
- seals cell
- prevents movement of fluids and ions between cells of 2 different body compartments
- degree of sealing can vary based on location in body
- can be regulated
- major types of proteins in tight junctions are claudins and occuludins
17
Q
Connexons
A
- hollow cylinders
- special type of protein grouped into an assembly of 6 subunits
- subunits are called connexins
- Takes 2 connexons from opposing cells normally sticking together to form complete gap junction
18
Q
Locations of Gap Junctions and why
A
- Muscle and Nerve = Rapid Communication
- Heart = facilitate flow of electrical current
- Brain = cerebellum for rapid muscle movement
19
Q
Pemphigus
A
- rare,severe autoimmune disease against cadherins in the body
- varying size blisters break out on skin, lining of mouth, genitals, and other mucous membranes
- other symptoms include loss of hair and skin falls/peels off
- occurs both in humans (middle-age or older) and animals (dogs, cats, horses, goats)
- Mainstay of treatmetn is high doses of corticosteroids
20
Q
Pemphigus vulgaris targets….
A
Dsg3
21
Q
IgA pemphigus targets…
A
Dsc1
22
Q
Pemphigus foliaceus targets…
A
Dsg1
23
Q
Pemphigus foliaceus
A
- least severe of 3 varieties of pemphigus
- Desmoglein 1, protien that is destroyed by autoantibody, is only found in top dry layer of skin
- symptoms = crusty sores that often being on skin of face, ears, and feet. Eventually on entire skin
- middle-aged to older dogs more prone to this disease
- more commonly seen in Akitas, Doberman pinschers, Chows, Dachschunds, Newfoundlands, Bearded Collies, and Schipperkes
24
Q
Natalizumab
A
- humanized monoclonal antibody against cellular adhesion molecule alpha4-integrin
- used in treatment of multiple sclerosis and Crohn’s disease
- could increase risk of infection
