cell adhesion/ECM

Question 1

specialized receptors used to connect cells to ECM

Answer 1

integrins

Question 2

how is integrin activity regulated

Answer 2

through clustering of receptors

Question 3

do integrins signal?

Answer 3

yes, can transduce signals from the environment into the cell, and can coordinate with receptor tyrosine kinase signaling to influence cellular processes

Question 4

T/F. Integrins have enzymatic domains

Answer 4

False, they do not, so they rely on cytoplasmic binding partner

Question 5

what connects basement membrane to intermediate filaments

Answer 5

hemidesmosomes

Question 6

focal adhesions

Answer 6

integrin based structures that connect ECM to actin cytoskeleton

Question 7

how is ECM produced?

Answer 7

it is secreted and assembled by cells

Question 8

what is the function of ECM?

Answer 8

mechanical support of tissues, also signaling and regulation of cell behaviors

Question 9

how is ECM organized

Answer 9

into fibers or sheets

Question 10

what are the major ECM classes (5)

Answer 10

adhesive glycoproteins, collagens, glycosaminoglycans, proteoglycans, elastic fibers

Question 11

what do fibrillar collagens organize into?

Answer 11

supramolecular fibrils and fibers

Question 12

Two mechanisms of integrin-mediated signaling

Answer 12

1. Inside out signaling: cells stimulated by growth factors or chemokines, activates intracellular protein talin, which binds to integrin and causes conformational change
2. Outside-in signaling: binding of integrins with ECM ligands induces conf change, tail binds to downstream signaling proteins

Question 13

Focal adhesion kinase pathway

Answer 13

1. Integrins bind to ECM ligands and cluster, recruit FAK
2. FAK gets autophosphorylated, creating binding sites for SH2 domain of Src
3. Src binds to FAK, does more phosphorylation, activates pathway further downstream

Question 14

T/F. Integrins sometimes have enzymatic activity

Answer 14

False, they do not have intrinsic enzymatic activity

Question 15

what are focal adhesions

Answer 15

dynamic junctions that connect migrating cells to ECM

Question 16

core cytoplasmic proteins in focal adhesion?

Answer 16

vinculin, talin, zyxin, paxillin, focal adhesion kinase

Question 17

basic model of cell migration (4)

Answer 17

1. Extension of lamella
2. Exert force on substratum
3. Retract the rear
4. Repeat

Question 18

ECM acts as a source of information - give examples

Answer 18

1. ECM ligation by integrins transduces signals that can regulate migration and proliferation
2. Proteolytic degradation is a way of accessing ECM information