Cell Adhesion

Question 1

Why is cell adhesion important?

Answer 1

It allows for organization of multicellular structures such as
tissue and organs

Question 2

Junctional

Answer 2

Cell-to-Cell

Question 3

Non-junctional

Answer 3

Cell-to-ECM

Question 4

Critical to cell communication and tissue formation

Answer 4

cell adhesion

Question 5

ECM

Answer 5

Consists of macromolecules secreted by cells into extracellular space, it is produced modified and oreinted by cells within it

Question 6

glycoproteins in ECM

Answer 6

organise matrix and cell into ordered structure

Question 7

Collagen in ECM

Answer 7

major component of basal lamina, strong adhesion of cells to basal lamina

Question 8

laminin

Answer 8

1. role in assembling ECM
2. promoting cell adhesion and growth
3. changing cell shape
4. permitting cell migration

Question 9

fibronectin

Answer 9

1. links cells to one another and to collagen and proteoglycans. provides proper alignment of cells within ECM

Question 10

Cell-to-ECM attatchment

Answer 10

can provide signals for biological processes, and depending on cell-tissue, attachment behaviour and function can vary

Question 11

integrins

Answer 11

cells ability to bind adhesive glycoproteins depends on expression of membrane receptors that can bind them.

Question 12

fibronectin receptor complex

Answer 12

binds fibronectin, vitronectrin and laminin (arginine-glycine-aspartate (RGD)) on outside of cell, and actin cytoskeleton on inside of cell. It spans the cell membrane, binding fibronectin in ECM and anchorages cytoskeleton on inside

Question 13

Integrin-matrix adhesion can regulate

Answer 13

cell signalling
gene expression
mitosis
apoptosis
cell differentiation

Question 14

Focal adhesion

Answer 14

macromolecular structure >50 proteins

Question 15

FA participate in:

Answer 15

anchorage, integrin-dependent signalling and actin dynamics

Question 16

FA components

Answer 16

scaffolding molecules, GTPases and enzymes. Numerous proteins that can shuffle between focal adhesion and nuclear compartments allowing communication between subcellular domains

Question 17

FA signalling

Answer 17

Tyrosine phosphorylation of FA proteins (paxillin and vinculin) by 2 kinases in FA (FAK & Src). Regulate dynamics and cell behaviour

Question 18

Cell Migration

Answer 18

Cell moves by contracting the actin filaments against the fixed ECM because of dual binding

Question 19

One of the most important contributors to cell fate in development

Answer 19

Cell Migration

Question 20

Cell Migration Steps

Answer 20

1. At leading edge of CM, protrusions are stabilized by nacent adhesive foci that mature into FA
2. At trailing edge, FA disassemble, allowing retraction of rear of cell
3. FA dynamics necessary for translocation of FA towards centre of cell and release of trailing edge of cell

Question 21

FA assembly

Answer 21

complex intracellular intercations regulated by: Tyrosine phosphorylation, FAK, Rho

Question 22

FA adhesion turnover/disassembly

Answer 22

regulated by: Kinase activity of Src and cleavage by calcium dependent protease, calpain

Question 23

Intracellular force

Answer 23

Rho/ROCK increase FA and stress fibre formation

Question 24

Extracellular force

Answer 24

rigidity of ECM strengthens integrin cytoskeletal link

Question 25

Force Regulation of FA

Answer 25

regulate cell migration/locomotion

Question 26

Cadherins

Answer 26

Calcium-dependent adhesion moleclules, interact with cadherins on adjacent cells, binding incredibly strong

Question 27

Surface tension

Answer 27

Surface tension of aggregates linearly related to expression of cadherin

Question 28

Catenins

Answer 28

Bind to cytoskeleton and anchor cadherins in place

Question 29

Actin cytoskeleton

Answer 29

Crucial in organizing cadherins so they form stable linkages

Question 30

E-Cadherin

Answer 30

early mammalian embryonic cells and epithelial cells

Question 31

P-Cadherin

Answer 31

placenta

Question 32

N-cadherin

Answer 32

CNS

Question 33

R-cadherin

Answer 33

retina

Question 34

B-Cadherin

Answer 34

many neural structures

Question 35

E- Cadherins and P-Cadherins

Answer 35

bind well, cells with these will be sorted according to cadherin expression

Question 36

Cell sorting

Answer 36

quantity and type of cadherins expressed determines this

Question 37

Cells expressing More cadherin

Answer 37

when mixed, greater adhesion and migrated internally

Question 38

R-cadherin and N-Cadherin

Answer 38

do not bind well

Question 39

selective cell adhesion

Answer 39

when mixed, cells adhere and cell types spatially segregate into own regions

Question 40

reaggregated cells

Answer 40

reflect embryonic position, showing selective affinity of germ layers

Question 41

differential adhesion hypothesis

Answer 41

when single cell suspensions combine, some cells migrate centrally and other peripherally

Question 42

A cell type 1 and cell type 2 show little to no adhesion

Answer 42

type1 and type 2 cells form separate aggregates

Question 43

type 1 and type 2 remain randomly mixed

Answer 43

type 1 type1 weaker or equal to type 1 type 2 or type 2 type 2

Question 44

Type 1 type 1 become central

Answer 44

type 1 type 1 stronger than type 1 type 2 or type 2 type 2

Question 45

desmosomes

Answer 45

Connect intracellular IF cytoskeleton of 2 adjacent cells via transmembrane desmosomal cadherins. Provide tissue with mechanical strength and resilience, particularly in high stress areas, skin and heart

Question 46

Plakoglobin and desmoplakinform

Answer 46

intracellular proteins that form a plaque which links cadherin to IFs

Question 47

"Rivets"

Answer 47

desmosome- cellular junction that provides string link between cells

Question 48

Adhesion belts

Answer 48

continuous bet like structures of adherens linked by internal actin cytoskeleton

Question 49

adherens junction

Answer 49

protein complex that provides cell-cell adhesion in tissues by connecting actin cytoskeleton to cadherins

Question 50

roles of adhesion belt

Answer 50

1. structural integrity 2. mechanotransduction - inform cell behaviour by sensing neighbouring cells 3. tissue development - contraction of actin network provides motile foces and cell migration and tissue morphogensis

Question 51

Formation provides tissues:

Answer 51

structural and mechanical integrity

Question 52

disease, particularly related to tissue integrity or function

Answer 52

1. cardiomyopathies 2. skin and hair disorders, pemphigus (skin blistering) 3. neurodevelopmental disorders 4. sensory defects, hereditary deafness

Question 53

integrin and FA defects diseases - signalling and migration

Answer 53

1. wound healing 2. vascular disease 3. cancer 4. blood clotting - glanzmanns thromboasthenia