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Chapter 5: Interactions between cells and their environment. - Coggle…
Chapter 5: Interactions between cells and their environment.
Introduction
crucial to the formation of
epithelial tissue
and
connective tissue
such as
cell migration
cell growth
cell differentiation
3D organization of tissue and organs
overview
:five::black_circle::one: Extracellular space - ECM
:red_circle::one: cell wall
bacteria, fungi, plants
gives polyhedral shape
"skeleton"
source of signal
made up of
cellulose - fibrous component of cell wall
protein & pectins - provide matrix
:red_circle::two: Glycocalyx
charged layer of membrane-bound biological macromolecules attached to cell membrane
fxn as barrier between cell and surroundings
composed of
glycosaminoglycans
proteoglycans
other glycoproteins
mediator for cell-cell and cell-substratum interactions
protects cell membrane from force/ stress
:red_circle::three: basement membrane
continuous sheet underlines epithelial tissue
surrounds blood vessels
helps maintain cells attached
serves as substratum for cell migration
barrier to macromolecules
:red_circle::four: up to ECM
role in determining shape & activities of cell
eg
support
adhesion
movement
regulation
gel-like "ground substance"
component
:red_circle::one: collagen
fibrous structural protein
most abundant protein in human body
provide high tensile strength
each collagen restricted to particular location
all collagens are a trimer of polypeptide chains wound around each other
provide insoluble framework
not all collagens from fibrils
collagen type IV non-fibrillar, restricted to basement membrane
abnormalities
Ehlers-Danlos syndrome
types
I
skin
tendon
bone
dentin
fascia
high tensile strengh
90% total body collagen
II
cartilage
nucleus pulposus
notochord
vitreous body
cornea
III
skin
uterus
blood vessels
reticular fibers
spleen
lymph nodes
:red_circle::two: proteoglycans
water hydrated gel
protein-polysaccharide complex, core protein attached ti glycosaminoglycans (GAGs)
repeating disaccharide structure
-ve charges GAGs attracts lots of cation, attract H2O forming porous hydrated gel
cell inter-communicator
types
inside the cell
control storage of proteases and compound in secretory granules
on the cell surface
modulate signaling pathways
bind extracellular ligands & transmit signals to the cytoskeleton
ECM
storage of growth and regulatory factors
basement membrane organisation
allow tissue to withstand compressive force
:red_circle::three: laminin
adhesive glycoprotein
major structure multidomain protein of basement membranes
extracellular glycoproteins consist of 3 polypeptide chains linkes by disulfide bonds
helps cell migration during development
:red_circle::four: fibronection
adhesive glycoprotein
involved in
tissue repair
embryogenesis
blood clotting
cell migration/ adhesion
exist in
insoluble
glycoprotein dimer serve as linker in ECM
soluble
disulphide linked dimer in plasma membrane
can be stretched during tension
degraded by matrix metalloproteinases (MMPs)
tissue remodeling
embryonic cell migration
wound healing
formation of blood vessels
:five::black_circle::two: cell - extracellular materials
:red_circle::one: integrin
composed of heterodimers with alpha & beta subunits
major role in integrating extracellular & intracellular environments
adhesion of cells to their substratum @ other cells
integrin + ligands = adhesion cell & environment
binding proteins to integrins facilitated by tripeptide RGD (Arg - Gly - Asp)
makes connection between ECM & cytoskeleton
activation mode
:red_circle::two: focal adhesions
a type of adhesive contact between cell & ECM
through interaction of transmembrane protein integrins with their extracellular ligands, intracellular multi protein assemblies connected to actin cytoskeleton
type of
sensory
structure
focal adhesion kinase (FAK) - protein tyrosine kinase recruited at early stage to focal adhesions
which mediates many of the downstream respones
composition
location
:red_circle::three: hemidesmosomes (HD)
contribute to the attachment of epithelial cells to the underlying basement membrane
in stratified and other complex epithelia
complex epithelia
skin
cornea
parts of gastrointestinal
respiratory tract
basal attachments - contain dense plaque with filaments consist of keratin
:five::black_circle::three: cell - other cells
surface recognition = intercellular junction
intercellular junction
:red_circle::one: selectins
family of integral glycoproteins bind to sugars on the cells surface
contains
cytoplasmic domain
single membrane-spanning domain
large extracellular segment
types
E-selectin
endothelial cells
P-selectin
platelets & endothelial cells
L-selectin
lymphocyte (WBC)
functions
lymphocytes homing
chronic & acute inflammation processes
skin inflammation
atherosclerosis
cancer metastasis
:red_circle::two: Immunoglobulin superfamily (IgSF)
involved in immune functions
mediate interactions lymphocytes with cells required immune response
:red_circle::three: tight junctions
components
occludins
Claudin proteins
junctional adhesion molecules
impermeable junctions prevent molecules from passing through the intercellular space
:red_circle::four: gap junctions
components
Connexin transmembrane protein
communicating junctions allow ions & small molecules to pass for intercellular communication
:red_circle::five: desmosomes
components
Cadherin family proteins
Desmoglein
Desmocollin
anchoring junctions bind adjacent cells together like a molecular "Veicro"
help form an internal tension-reducing network of fibers
:red_circle::six: plasmodesmata
in plant cell
addition - Adheren junctions
components
Cadherin adhesion receptors cytoplasmic proteins
