Cell-Cell and Cell-Matrix Interactions Flashcards Preview

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Flashcards in Cell-Cell and Cell-Matrix Interactions Deck (30):
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ECM - def.

Material found between cells.
Dynamic

Exception - not found between sheets of cells in an epithelial layer

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ECM - Functions

Hold tissue together, strength, elasticity, cushioning, adhesion, provide environmental cues to cell, modulate interactions between cells and their environment, provide a lattice upon which cells can move, involvement in signaling, reservoir for many extracellular signaling molecules that control cell growth and differentiation.

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ECM - Components

Collagen Fibers
Elastin Fibers
Proteoglycans
multiadhesive matrix proteins

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How do cells interact?

Intracellular interactions and cell-matrix interactions

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CAM's (list)

Cadherins
Selectins
Intergrins
Immunoglobulin

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Cadherins - def., function, composition

Calcium dependent glycoproteins
Mediate adhesive interactions between homotypic or heterotypic cells
Consists of intracellular, transmembrane and intercellular domains
Broadly distributed or clustered

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Cadherins - types, works with

E Cadherin - epithelial
P Cadherin - Placental
N Cadherin - neural

Adapter Proteins

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Adapter Proteins - function, types

Directly or indirectly connect cadherins to the cytoskeleton microfilaments (actin)
Recruit intracellular molecules that function in signaling pathways that allow for bidirectional signaling for cell growth and motility
Alpha and Beta Catenin

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Down regulation of E-Cadherin

decreases strength of intercellular adhesion and enhances cellular motility - allows cancer cells to cross basement membrane

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Loss of E-Cadherin

Leads to disintegration of the E-cadherin-catenin complex - results in release of signal molecules which my be involved in cell invasiveness

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N-cadherin expression in breast tissue

Not normally expressed in normal mammary epithelium
Upregulated in breast cancer (alongside E-cadherin loss)

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Selectins - Def.

Calcium-dependent vascular adhesion molecules - glycoproteines
Produced by endothelial cells

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Selectin - Function

Involved in the interactions between the endothelium, leukocytes, and platelets in the inflammatory process

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Selectin - types/role

E-selectin - endothelial-leukocyte adhesion molecule
P-selectin - recruitment of platelets
L-selectin - found on leukocytes

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E & P selectin - action

Interact with leukocytes, slow them down near site of infection

Leukocyte recruitment to infection

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Selectin mediate adhesion

Weak allowing leukocyte rolling along endothelium

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E- Selectin Overexpression

associated with more positive lymph node metastasis in breast cancer

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Intergrins - def., components

Cell surface glycoproteins
Receptors for ECM components
extracellular, transmembrane, and intracellular components

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Integrins - Function

Control organization of the cytoskeleton of migration and extravasion of leukocytes.
Cell adhere to a substrate though their intergrins
Regulate many biologic processes

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ICAM-1 a.k.a

Intercellular adhesion molecule, I

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ICAM-1, function

creates a tighter adhesion to stop leukocytes at infected site from rolling along by binding tightly to intergrins on leukocyte surface

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Leukocyte-adhesion deficiency - def., symp.

Rare genetic defect in synthesis of intergrin subunit.
Patients susceptible to repeated bacterial infection and non-healing wounds because their leukocytes cannot extravasate, migrate and phagocytose bacteria properly

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Integrin & E Cadherin

Integrin activation down-regulates E-cadherin thus allowing cancer cells to cross basement membrane due to decreased strength of intercellular adhesion and enhancement of cellular motility

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Integrin signaling

modulates expression and/or activity o matrix metalloproteinases (MMPs) which break down components of the matrix allowing passage of cells.

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Immunoglobulin superfamily - def., function

Group of adhesive receptors characterized by presence of multiple Ig domains (repeats) in their extracellular regions.
Involved in recognition, binding or adhesion of cells

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Immunoglobulin superfamily - members

cell surface antigen receptors, ICAM-1, antigen-presenting molecules, leukocyte receptors, growth factor receptors

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Laminins - def., sturcture

Protein of cell-associated matrices and basement membrane

Large flexible complex of 3 long polypeptide chains (A, B, Y) held together by disulfide bonds

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Laminins - function

Functional domains that bind to cells, collagen, and other matrix molecules
Bind cells to the basement membrane

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Laminin-332 - function

Attached cells to basement membrane and inhibits their movement
In Tumors - promote migration
Positive and negative repercussions

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Defetive laminins cause?

muscular dystrophy type
lethal skin blistering disease
defect of kidney filtration system