process extension/growth cone

Question 1

what are the three steps of process navigation

Answer 1

detection of ligand and receptor
cytoplasmic signaling
motile response

Question 2

what is involved in detection of ligand by the receptor

Answer 2

growth factors, chemoattractant and ECM. PTK receptors, cell adhesion molecules and neurotransmitters

Question 3

what is involved in cytoplasmic signaling

Answer 3

calcium influx, protein kinase phosphatase, Rho/Rac/CDC42, IP3 and PIP2

Question 4

what is involved in motile responses

Answer 4

actin-myosin and binding proteins, microtubules and binding proteins, GAP43 (growth associated protein), membrane flow

Question 5

how is Rho active?

Answer 5

when bound to GTP

Question 6

what causes faster turnover of Rho activity?

Answer 6

Rho GAP.

Question 7

what causes slower Rho activity

Answer 7

Rho GDI

GDP-dissociation inhibitor

Question 8

what causes increased Rho activity

Answer 8

Rho GEF. GTP exchange factor

Question 9

what factors activate neurite extension, what evidence

Answer 9

Rac, CDC42, RhoG

activated versions enhance neurite outgrowth

Question 10

what factors inhibit neurite extension or cause neurite retraction, evidence

Answer 10

RhoA

clostridium, blocks RhoA, blocks growth cone collapse

Question 11

what does Rac do and in what cellular system

Answer 11

actin polymerization in the lamelipodia

Question 12

what does Rho do and in whatcellular system

Answer 12

actin bundling in stress fibers

Question 13

what does CDC42 do and in what cellular system

Answer 13

actin polymerization in filapodia

Question 14

CDC42 mechanism

Answer 14

binds PIP2 and N-WASP and uses GTP to activate Arp2/3 to cause branching of actin filaments (70 degrees)

Question 15

Rho family mechanism

Answer 15

rho family activity causes confirmational change in ERM (ezrin, radixin, moesin) proteins which causes binding to icams and F-actin

Question 16

regulation of cofilin by Rho family

Answer 16

activation of Rho activates LIMK which stabilizes actin polymerization by phosphorylating cofilin.

Question 17

regulation of cofilin by Rac

Answer 17

same as Rho family

Question 18

how does slingshot regulate cofilin

Answer 18

it dephosphorylates cofilin which then causes F-actin severing and depolarization

Question 19

ENA/Vasp proteins in process extension

Answer 19

binds Lpd membrane proteins, linking them to F-actin. this stabilizes the association between the membrane and F-actin

Question 20

how do Rho family proteins regulate actin polymerizatoin

Answer 20

through activation of PAK, WASP, ERM and cofilin

Question 21

how do ENA/VASP proteins regulate actin dynamics

Answer 21

cell surface receptor, actin/profilin binding, filamentous actin binding, by blocking actin capping proteins

Question 22

how does membrane flow work in process extensino

Answer 22

1) membrane is endocytosed from areas not actively extending
2) membrane is generated de novo and transported through the golgi network

Question 23

secretory mutants cause defects in what?

Answer 23

dendrites, not axons.

laser ablation of golgi outposts cause dendrite outgrowth defects.

Question 24

what regulates kinesin-dependent axonal growth

Answer 24

UNC-69/73. they link kinesin motors to vesicles

Question 25

what is an intact secretory pathway required for?

Answer 25

dendritogenesis

Question 26

does ER-to-golgi transport affect growth of axons

Answer 26

no

Question 27

dendritic branches require what

Answer 27

golgi outposts

Question 28

how are microtubules oriented in axons

Answer 28

in a uniform manner plus-end-distal.

Question 29

what are par genes for

Answer 29

asymmetric orientations. they distinguish anterior and posterior poles of the embryo

Question 30

par1

Answer 30

S/T kinase MARK in mammals

Question 31

par 2

Answer 31

ring finger protein (ubiquitin pathway

Question 32

par3

Answer 32

PDZ domain protein (scaffold)

Question 33

par 4

Answer 33

S/T kinase (LKB1 in mammals)

Question 34

par5

Answer 34

member of the 14-3-3 pathway

Question 35

par6

Answer 35

PDZ scaffold

Question 36

par 3/6 localization

Answer 36

apical pole

Question 37

par 1/2

Answer 37

localized to lateral basal

Question 38

par 4/5

Answer 38

equally distributed

Question 39

are distinct domains actively maintained? how?

Answer 39

yes. by phosphorylation

Question 40

apical domain sequestration

Answer 40

aPKC phosphorylates par-1 leading to par-5 binding, preventing association with the membrane

Question 41

lateral domain

Answer 41

par-1 phosphorylates par-3 releasing it from the membrane

Question 42

what proteins are required for establishing the apical/basal regions

Answer 42

par proteins, aPKC/CDC42

Question 43

what is the first polarizing event in neurons

Answer 43

axonogenesis

Question 44

what happens when you sever an axon

Answer 44

new axon formatino

Question 45

what factor causes supranumery axons

Answer 45

cytochalazin D

Question 46

where does mPar6 localize

Answer 46

tip of nascent axon

Question 47

what factor is required for axon initiation

Answer 47

aPKC

Question 48

what can we inhibit to block polarization

Answer 48

PI3K

Question 49

how is LKB1 regulated

Answer 49

binding STRAD and MO25 recruits it to the cytoplasm, stabilizes it and activates it kinase activity

Question 50

what are the downstream substrates of LKB1

Answer 50

MARK (Par1) and SAD kinases

Question 51

what does inactivation of LKB1 causes what

Answer 51

peutz-Jaghers cancer syndrome

Question 52

what does STRAD expression do

Answer 52

stabilizes LKB1 in one process prior to axon specification

Question 53

what happens when LKB1 inactivated

Answer 53

loss of axon initiation

Question 54

LKB1 + STRAD = ?

Answer 54

more axons

Question 55

how is axon/dendrite polarity initiated

Answer 55

neuronal migration