Histology Lecture 5: CAMs and Junctional Complexes Flashcards
a sheetlike extracellular matrix in direct contact with epithelial cell surfaces; results from the self-assembly of laminin molecules with type IV collagen, entactin, and proteoglycans
basal lamina
formed by type III collagen fibers, supports the basal lamina and is continuous with the connective tissue
reticular lamina
separates an epithelial layer from its connective tissue support; PAS+
basement membrane
part of the basement membrane produced by the epithelium
basal lamina
part of the basement membrane produced by the connective tissue
reticular lamina
does not form fibrils and is produced by epithelial cells
Type IV Collagen
forms fibrils and is secreted by fibroblasts
Type I Collagen
major component of the basal lamina with binding sites for integrins, type IV collagen, entactin, and proteoglycans
Laminin
Components of the basal lamina
Laminin, Fibronectin, Type IV collagen, entactin (nidogen) and proteoglycans
cross shaped protein consisting of three chains (alpha, beta, and gamma); can associate with one another and form a meshlike polymer (i.e matrix)
laminin
two protein chains crosslinked by disulfide bridges; the main adhesion molecule of the extracellular matrix; produced by fibroblasts; binding sites for proteoglycans, integrins, collagen, and fibrin
fibronectin
calcium dependent cell adhesion molecules
cadherins and selectins
calcium independent cell adhesion molecules
integrins and immunoglobulin superfamily molecules
link two cell’s cytoskeletons together; form cis- homophilic dimers via HVA binding face when Calcium ion binds
E-cadherin
found along the lateral surface of the cell and involved with the maintenance of most epithelial layers
E-cadherin
loss is assocated with invasive behaviour of tumour cells
E-cadherin
small proteins that link cytoplasmic end of a cadherin with cytoplasmic actin
catenin
attached to cytoplasmic end of cadherin;
beta and gamma catenin
binds directly to cytoplasmic actin
alpha catenin
serve as a major interface between the cadherins that hold adjacent cells together and the actin cytoskeletons of those cells
catenins
bind to carbohydrates and are involved with the movement of leukocytes from blood into tissue (extravasation)
selectins
selectins associated with platelets and activated endothelial cells lining blood vessels
p-selectin
selectins associated with activated endothelial cells
e-selectins
selectins associated with leukocytes
l-selectins
a specific oligosaccharide ligand for P-selectin associated with leukocyte extravasation
sialy Lewis-x antigen
glycoproteins mainly involved with cell-extracellular matrix interactions; link the cell to the extracellular matrix; bind both cytoskeleton and extracellular matrix
integrins
sequence in fibronectin and laminin that interact with extracellular domain of integrins
RGD
Members of this family possess an extracellular segment with one or more folded domains characteristic of
immunoglobulins
Immunoglobulin superfamily
These are molecular complexes that anchor cells together and reinforce the physical integrity of tissues and the cells that make up the tissues; can be found on the basolateral surfaces of epithelial cells
adherens
These are molecular complexes that establish an impermeable barrier between adjacent cells, especially epithelial cells, that prevents paracellular transport and maintains concentration differences between the environments on either side of the epithelial sheets
occludens
These are composed of molecular pores that enable cells to rapidly exchange ions and small molecules that help coordinate activities among the cells that make up the tissue
gap junctions
complexes that travel all the way around the circumference of the cell and link all neighboring cells to the central cell. They are sometimes referred to as belt-like complexes; associated with intracellular actin
zonula
a “spot” or snap-like junction. They are of the adherens
variety and are often referred to as desmosomes (associated with the lateral domains of epithelial cells) or hemidesmosomes (associated with the basal domain of epithelial cells). They are associated with intracellular intermediate filaments (tonofilaments).
Macula
anchoring junctions characterized by intercellular spaces filled with cadherin proteins (desmogleins and desmocollins)
adherens
autoantibodies to desmoglein 1 cause this
pemphigus foliaceus
autoantibodies to what cause pemphigus foliaceus
desmoglein 1
make up cytoplasmic plaques
desmoplakin and plakoglobin
a spotlike junction associated with keratin intermediate filaments
(also known as tonofilaments ) extending from one spot to another on the lateral and basal cell surfaces of epithelial
cells
macula adherens/desmosome
associated with actin microfilaments
zonula adherens
anchoring junctions that anchor the basal domain of the epithelial cell to the basal lamina
hemidesmosome
provide a barrier against the paracellular transport pathway whereby solutes and fluids are transported from one side of an epithelial barrier to the opposite side by passing between the cells
occluding junctions/tight junctions
transmembrane proteins associated with the junctional complex and are responsible for the occlusive properties of the tight junction; they attach intracellularly to zonula occludens proteins ZO-2 and ZO-3
claudins and occludins
members of the immunoglobulin superfamily. They are stabilized by disulfide bonds and form cishomodimers that facilitate cell adhesion
Junctional Adhesion Molecules and Nectin
associated with afadin (intracellular molecule)
Nectin
associated intracellularly with afadin and ZO-1
JAMs
spots that anchor the cell to the extracellular matrix via integrins; differ from desmosomes because the intracellular attachment is to actin microfilaments via connecting proteins instead of tonofilaments
focal adhesions
close when calcium ion concentrations are high
gap junctions
type of collagen most associated with the basal lamina
Type IV
type of cell adhesion molecules is associated with zonula occludens and desmosomes
cadherins
Desmocolloin and desmogleins belong to which of the following groups of CAMs
cadherins
seve as a major interface between the cadherins that hold adjacent cells together and their actin cytoskeletons
catenins
The extracellular domains bind to molecules in the extracellular matrix such as fibronectin and laminin
integrins
molecular complexes that anchor cells together and reinforce the physical integrity of tissues and the cells that make up the tissue
zonula adherens
molecular complexes that primarily serve to prevent paracellular
transport
zonula occludens
