T&H8 Cellular Signaling Pathways

Question 1

Name three growth factor receptors with split kinase domains, in which autophosphorylation sites are present on a kinase insert with in the catalytic subunit.

Answer 1

PDGFR
VEGFR
KIT (SCFR)

Question 2

Name 2 growth factors that are monomeric polypeptides.

Answer 2

EGF and FGF

Question 3

Name a growth factor that is a dimeric polypeptide.

Answer 3

PDGF

Question 4

When EGF binds to EGFR, a conformational change of the extracellular domain occurs. This leads to dimerization of _______ and intracellular autophosphorylation of ______ residues, which opens up the catalytic site and creates docking sites for cytoplasmic adaptor proteins, such as ______ and ______, that contain ______ or ______ domains.

Answer 4

• RTKs
• tyrosine
• GRB2 and p85
• SH2 or PTB

Question 5

Following binding of GRB2 to the activated RTK (via its SH2 domain), it associates with _____, which is an GEF, via its _____ domain. _____ catalyzes exchange of GDP to GTP on Ras for activation. Ras binds _____, which activates a kinase cascade including ____ and _____.

Answer 5

• SOS
• SH3
• SOS
• RAF
• MEK and ERK

Question 6

Mutations in juxtamembrane regulatory regions of ____ and ____ are implicated in human GISTs.

Answer 6

c-kit
FLT3

Question 7

Binding of specific domains to their target sometimes requires phosphorylation of ________ within the sequence-specific binding motif.

Answer 7

amino acids

Question 8

Proteins that contain either ____ or ____ domain, which recognize phosphorylated sequence motifs, are central for the formulation of signaling complexes following activation of GF RTKs.

Answer 8

SH2 or PTB

Question 9

______ is an SH2 and SH3 domain-containing adaptor protein that plays a critical role in activation of small GTPase protein, Ras.

Answer 9

GRB2

Question 10

Termination of RAS activity occurs via _____ of GTP, converting to GDP by ______.

Answer 10

• hydrolysis
• GAPs

Question 11

RAS is activated by effects of ____, which release RAS-bound GDP and allows GTP binding to RAS.

Answer 11

GEFs

Question 12

Besides RAF, RAS also interacts with _____ and ______.

Answer 12

PI3 kinases and RALGDS

Question 13

What are the three distinct MAPK pathways?

Answer 13

1. ERK1/2
2. JNK/SAPK
3. p38

Question 14

MAPK pathway is activated by phosphorylation of _______ and ______ residues.

Answer 14

threonine and tyrosine

Question 15

RAS leads to activation of ______ (MAP3K), which then activates _______ (MAPKK) via phosphorylation of ______ residues. MAPKK activates ______ (MAPK) via phosphorylation of ______ and ______ residues. MAPK activation induces phosphorylation of cytoplasmic and nuclear proteins that regulate ________, ________, and ________. MAPK also phosphorylates ______ proteins and _____ family of protein kinases, which regulate translation. transcription, and survival signaling. MAPK translocates to nucleus to activate ____.

Answer 15

• RAF
• MEK 1/2
• serine
• ERK
• threonine and tyrosine
• cell migration, proliferation, and differentiation
• cytoskeletal proteins and RSK
• TFs

Question 16

PI3 kinase is comprised of a catalytic subunit ______ and regulatory subunit ______.

Answer 16

• p110
• p85

Question 17

p85, the regulatory subunit of PI3K, contains two _____ domains

Answer 17

SH2

Question 18

Binding of p110/p85 complex to activated growth factor receptors via _____ SH2 domain activates catalytic activity of _____, which then phosphorylates ____, converting it to PIP3. PIP3 recruits _____- domain containing proteins, such as _____ and _____. ____ contributes to activation of ______.

Answer 18

• p85
• p110
• PIP2
• PH-domain
• AKT and PDK1
• PDK1
• AKT

Question 19

AKT leads to activation of _____, which regulates cell growth. It also phosphorylates and causes nuclear exclusion of _____ transcription factors, which prevents expression of genes that induce cell death.

Answer 19

• TORC1
• FOXO

Question 20

mTOR is a serine threonine kinase that forms 2 distinct complexes, _____ and _____. Name the main function of each complex.

Answer 20

• TORC1: controls/promotes cell proliferation
• TORC2: promotes cell growth by activating AKT

Question 21

Rapamycin is an _____ inhibitor and is used as an ________.

Answer 21

• mTOR
• immunosuppressant

Question 22

The rapamycin analogs, ________ and _______, can be used to treat what cancer in people?

Answer 22

• temsirolimus and everolimus
• RCC

Question 23

______ functions are a major negative regulator of PI3K signaling.

Answer 23

PTEN

Question 24

Substrates for AKT fall into 2 main classes as regulators of ______ or regulators of _____.

Answer 24

• cell survival
• cell proliferation

Question 25

Transcription of genes is catalyzed by _______ and regulated by supporting molecules termed ______.

Answer 25

- RNA polymerase II - transcription factors

Question 26

Activity of transcription factors can be modified by phosphorylation through activity of signaling pathways, such as _____ and ____, which can act in the nucleus to directly modify TF activity.

Answer 26

- MAPK and PI3K

Question 27

Name the 4 groups of transcription factors and give an example of each.

Answer 27

1. Homeodomain (a.k.a. helix-turn-helic) - Ex) oct 1 2. Zinc finger - Ex) glucocorticoid receptor 3. Leucine zipper - Ex) c-jun 4. Helix-loop-helix - Ex) myc

Question 28

Enzymes that regulate ________________________ are key components of transcriptional activator and repressor complexes.

Answer 28

histone acetylation and phosphorylation

Question 29

Histone _____ near the promoter regions of genes facilitates interaction of DNA with TFs.

Answer 29

acetylation

Question 30

The ________ pathway is an important mechanism for signal termination.

Answer 30

ubiquitination

Question 31

In the ubiquitination pathway, free ubiquitin attaches to _________ and is transferred to ______. In partner with __________, ubiquitin is transferred to a substrate. Polyubiquinated substrates are degraded by ________. Monoubiquinated substrates serve as signal for receptor _______. which is then transferred to a _______ for degradation.

Answer 31

- ubiquitin-activating enzyme (E1) - ubiquitin-conjugating enzyme (E2) - ubiquitin ligase (E3) - 26S proteosome - endocytosis - lysosome

Question 32

Receptors in cytokine signaling do not contain intrinsic TK activity, but instead transmit intracellular signaling through _______ family of kinases.

Answer 32

JAK

Question 33

_____ domain functions to both regulate JAK kinase activity and mediate association with receptors.

Answer 33

FERM

Question 34

Cytokine binding leads to ______ phosphorylation of the GBP130 receptor subunit via specific ______ residues. This recruits _____, which binds via its _____ domain and becomes phosphorylated via ____ residues and is transported to _____ to regulate gene expression. GBP130 phosphorylation also results in recruitment of tyrosine phosphatase, ___, which is turn leads to ____ activation.

Answer 34

- JAK - Tyrosine - STAT - SH2 - Tyrosine - nucleus - SHP2 - Ras

Question 35

In addition to JAK, STAT can be phosphorylated by ______ and ___.

Answer 35

mTOR and ERK

Question 36

_______ is a JAK 2 inhibitor that reduces tumor burden and improves QOL, but does not cause remission.

Answer 36

Ruxolitinib

Question 37

Gene translocations and activating point mutations in JAK2 have been identified in _______ and ____.

Answer 37

myeloproliferative disorders and leukemia

Question 38

Are integrins upregulated or downregulated in tumor progression? Or both?

Answer 38

both up and down regulation

Question 39

Loss of integrin _____ is observed in some tumors.

Answer 39

a2B1

Question 40

Upregulation of integrins ____, ______, and ____ are seen in epithelial tumors.

Answer 40

avB3, avB6, and a5B1

Question 41

Name developmental signaling pathways. Hint: there's 6.

Answer 41

- WNT - HH - TGF-B - NOTCH - JAK/STAT - nuclear hormone pathways

Question 42

The ______ family of transmembrane receptors are seen in Wnt signaling pathway.

Answer 42

Frizzled (FZ)

Question 43

Name the 3 Wnt pathways.

Answer 43

1. Canonical (major) WNT pathway 2. WNT/Planar cell polarity pathway 3. WNT/Ca2+ pathway

Question 44

What is the key mediator of the canonical WNT pathway?

Answer 44

B-catenin

Question 45

WNT activation leads to inactivation of the destruction complex, which leads to _____ accumulation and entry into the nucleus where it interacts with _____ and ____ family of TFs to regulate transcription of target genes.

Answer 45

- B-catenin - LEF and TCF

Question 46

What are the target genes of the WNT pathway?

Answer 46

c-myc, MMP-7, cyclin D1

Question 47

What syndrome is associated with upregulated WNT signaling? Mutations in the _____ tumor suppressor gene leads to ineffective B-catenin degradation and constitutive activation of B-catenin/TCF targent genes.

Answer 47

- Familial adenomatous polyposis (FAP) - APC

Question 48

What are the ligands and receptors of the NOTCH pathway?

Answer 48

- Ligands: DELTA-LIKE 1, 3, 4, and JAGGED 1-2 - receptors: NOTCH 1-4

Question 49

In NOTCH signaling, the ligand binds to its receptor, which causes a release of the extracellular domain mediated by ______. This triggers cleavage by ________ complex, releasing ________. This enters the nucleus and converts ____ repressor to an activator of transcription.

Answer 49

- ADAM family of MMPs - gamma-secretase - NOTCH intracellular domain (NIC) - CSL

Question 50

NOTCH1 activation, resulting from a chromosomal translocation, is strongly linked to humans cancers, such as ______.

Answer 50

T-ALL

Question 51

What are potential therapy targets for NOTCH signaling?

Answer 51

inhibition of gamma-secretase (GSI) or ADAM

Question 52

Hedgehog gene products encode ligands that signal through membrane receptor complexes, ______ and ____.

Answer 52

Patched (PTC) and Smoothened (SMO)

Question 53

In HH signaling, ____ inhibits ____ in absence of ligand.

Answer 53

PTC inhibits SMO

Question 54

When HH ligand binds to its receptor _____, there is a release and activation of ______, which allows expression of zinc-finger transcription factors and transcription of HH target genes.

Answer 54

- PTC - SMO

Question 55

HH pathway can lead to cancer through several mechanisms including loss of function of TSG ______ or gain of function through oncogene ______.

Answer 55

PTC1 SMO

Question 56

Inhibition of _____ signaling in stroma can improve delivery of cytotoxic chemotherapy.

Answer 56

HH

Question 57

In ________ cancer, HH signaling is upregulated and accompanied by elevated expression of ______, which is a protein involved in EMT and metastasis.

Answer 57

- primary colon cancer - SNAIL

Question 58

What is TGF-B's role in cancer?

Answer 58

functions as a antiproliferative factor and tumor promoter

Question 59

TGF-B is activated following dimerization and binds to type I and type II receptors, which leads to _________ phosphorylation and activation of kinase domain of type I and type II receptors. Activated type I signals to ____ family of mediators, which carry the signal from cell surface directly to _______.

Answer 59

- unidirectional - SMAD - Nucleus

Question 60

Inhibitory SMADs counteract receptor-regulated SMADs (R-SMADs) and antagonize ______ signaling.

Answer 60

TGF-B

Question 61

______ and ____ are E3 ubiquitin-protein ligases that regulate SMAD levels and orchestrate ubiquitin transfer to the _____ SMADs leading to degradation.

Answer 61

- SMURF 1 and SMURF 2 - R-SMADs

Question 62

What is the growth factor receptor for SCF (stem cell factor)?

Answer 62

c-kit

Question 63

What are the growth factor receptors for HGF (hepatocyte growth factor)?

Answer 63

MET, RON

Question 64

What is the ligand for HER2?

Answer 64

HER2 does not have a known ligand

Question 65

What are the growth factor receptors (a.k.a targets) for Palladia?

Answer 65

- VEGFR2 - PDGFRB - KIT - CSF1R - FLT3

Question 66

What are the growth factor receptors (a.k.a targets) for Masitinib?

Answer 66

- KIT - PDGFRa/B - Lyn - Fyn - FGFR3

Question 67

Phosphoinositidines are phospholipids from _______. They are dynamically regulated in response to growth factor signaling. They contribute to signal propragation via two main mechanisms. The first is by serving as precursors of the second messengers _______ and ________. The second is by binding to signaling proteins that have PI binding molecules.

Answer 67

- cell membrane - diacylglycerol (DAG) and inositol triphosphate and Ca2+

Question 68

Which cyclin is primary responsible for regulating Rb protein?

Answer 68

D-type cyclins

Question 69

Most cytokine receptors have unique extracellular ligand binding region, a single transmembrane domain, and a cytoplasmic domain. Do most of the receptors exist as single chain OR multi-subunit chains?

Answer 69

With exception of the receptors for G-CSF and erythropoietin, most cytokine receptors are multisubunit complexes

Question 70

______ mediate cellular interaction between the ECM and actin skeleton, which enables direct communication across plasma membrane.

Answer 70

Integrins

Question 71

B-catenin is abnormally expressed in canine _____ and ______ but doesn't correlate with outcome nor does targeting the WNT pathway seem relevant.

Answer 71

OSA and melanoma

Question 72

HES1, a target of NOTCH signaling, is elevated in canine ______ but reduced in most aggressive tumors.

Answer 72

OSA

Question 73

HH signaling is activated in canine _____ and contributes to cell proliferation and survival. Inhibition with ________ and _____ led to significantly decreased cell proliferation but had smaller effect on apoptosis.

Answer 73

- TCC - Cyclopamine and GANT61

Question 74

Canine ____ cell lines possess TGF-B1 signaling machinery, potentially allowing for establishment of autocrine and paracrine pro-tumorigenic signaling loop. TGFB1 inhibitors might impede localized progression in dogs.

Answer 74

OSA

Question 75

______ is an enzyme that removes a high energy phosphate group from ATP and transfers it to a protein substrate.

Answer 75

Kinase

Question 76

What are two types of TGF-B family serine threonine receptors and how do they differ?

Answer 76

- Type I: normally inactive - Type II: constitutively active but do not normally phosphorylate substrates - ligand mediated dimerization causes type II to phosphorylate type I, which converts it to an active kinase

Question 77

What event markedly reduces activity of most kinases?

Answer 77

dephosphorylation of T loop (transactivation loop)

Question 78

JAKs contain a _____ domain, which stands for _____________, an SH2 domain, a functional kinase domain, and a ______ domain that can exert auto-inhibitory activity on the kinase domain. The function of the _____ domain is unclear because it does not appear to bind to tyrosine phosphorylated proteins.

Answer 78

- FERM - F (4.1 protein), E (ezrin), R (radixin) and M (moesin) - kinase-like domain - SH2

Question 79

Activated JAK receptor generates docking sites for SH2 domain containing proteins, such as _____, ______, and ______.

Answer 79

- STAT - PI3 kinase - GRB2

Question 80

STATs contain a conserved _________ domain that is specific to the STAT family, a conserved _____ domain, and a carboxyterminal _____ residue that mediates dimerization.

Answer 80

- aminoterminal DNA binding - SH2 domain - tyrosine

Question 81

Point mutations, such as ______, are found frequently in myeloproliferative diseases and thought to disrupt the auto-inhibitory activity interaction between pseudokinase and catalytic kinase domain of JAK.

Answer 81

V617F

Question 82

STAT upregulates what target genes and downregulates ___.

Answer 82

- upregulation: Mcl-1, survivin, BCL-2, and VEGF - Inhibits p53

Question 83

TORC1 controls protein synthesis through phosphorylation of ____ and ______ that in turn promote cap-dependent protein translation.

Answer 83

- eukaryotic translation initiation factor binding protein (4R-BP1) - S6 kinase 1 (S6K1)

Question 84

TORC1 regulates ATP production and metabolism by promoting the expression of ________ that regulates expression of glycolytic genes controlling glucose metabolism.

Answer 84

HIF-1a

Question 85

TORC1 inhibits autophagy by phosphorylation and inhibition of the activity of ______, which forms part of a kinase complex required to initiate autophagy.

Answer 85

autophagy-related gene 13 (ATG13)

Question 86

TORC2 promotes cell growth through activation of protein kinases _____, ______, and ____.

Answer 86

AKT, SGK1, PKCa

Question 87

Anabolic state is programmed by growth factor signaling pathways and transcription factors, particularly the ________ network and _____.

Answer 87

PI3K/mTOR c-myc

Question 88

______ kinase acts as a central regulator of cellular metabolism by integrating upstream signaling pathways that monitor growth factors, energy and nutrients, and coupling them to regulation of protein synthesis and ribosomal biogenesis, autophagy, and metabolism.

Answer 88

mTOR

Question 89

_______ inhibits mTOR signaling through multiple pathways, both upstream and downstream of the kinase, particularly in concert with other stresses.

Answer 89

hypoxia

Question 90

Inhibition of ______ stimulates autophagy.

Answer 90

mTOR

Question 91

"Cap-independent translation" affects several important genes, including _____ and _____, which facilitates tumor growth in locally advanced breast cancers.

Answer 91

HIF-1a and VEGF

Question 92

_____ inhibition promotes tolerance to hypoxia, which can increase the proportion of viable hypoxic cells and reduce effectiveness of other therapies.

Answer 92

mTOR

Question 93

If a substrate is recognized by ______, they may hydrolyze the covalent bond with ubiquitin from the substrate, preempting substrate degradation

Answer 93

deubiquinating enzymes