Cell-Cell and Cell-Matrix Interactions Flashcards
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.
ECM - def.
Material found between cells.
Dynamic
Exception - not found between sheets of cells in an epithelial layer
ECM - Components
Collagen Fibers
Elastin Fibers
Proteoglycans
multiadhesive matrix proteins
How do cells interact?
Intracellular interactions and cell-matrix interactions
CAM’s (list)
Cadherins
Selectins
Intergrins
Immunoglobulin
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
Cadherins - types, works with
E Cadherin - epithelial
P Cadherin - Placental
N Cadherin - neural
Adapter Proteins
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
Down regulation of E-Cadherin
decreases strength of intercellular adhesion and enhances cellular motility - allows cancer cells to cross basement membrane
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
N-cadherin expression in breast tissue
Not normally expressed in normal mammary epithelium
Upregulated in breast cancer (alongside E-cadherin loss)
Selectins - Def.
Calcium-dependent vascular adhesion molecules - glycoproteines
Produced by endothelial cells
Selectin - Function
Involved in the interactions between the endothelium, leukocytes, and platelets in the inflammatory process
Selectin - types/role
E-selectin - endothelial-leukocyte adhesion molecule
P-selectin - recruitment of platelets
L-selectin - found on leukocytes
E & P selectin - action
Interact with leukocytes, slow them down near site of infection
Leukocyte recruitment to infection
Selectin mediate adhesion
Weak allowing leukocyte rolling along endothelium
E- Selectin Overexpression
associated with more positive lymph node metastasis in breast cancer
Intergrins - def., components
Cell surface glycoproteins
Receptors for ECM components
extracellular, transmembrane, and intracellular components
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
ICAM-1 a.k.a
Intercellular adhesion molecule, I
ICAM-1, function
creates a tighter adhesion to stop leukocytes at infected site from rolling along by binding tightly to intergrins on leukocyte surface
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
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
Integrin signaling
modulates expression and/or activity o matrix metalloproteinases (MMPs) which break down components of the matrix allowing passage of cells.
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
Immunoglobulin superfamily - members
cell surface antigen receptors, ICAM-1, antigen-presenting molecules, leukocyte receptors, growth factor receptors
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
Laminins - function
Functional domains that bind to cells, collagen, and other matrix molecules
Bind cells to the basement membrane
Laminin-332 - function
Attached cells to basement membrane and inhibits their movement
In Tumors - promote migration
Positive and negative repercussions
Defetive laminins cause?
muscular dystrophy type
lethal skin blistering disease
defect of kidney filtration system
