Biochemistry Quiz 6

Question 1

What are cytokines?

Answer 1

-small proteins
-control growth/activity of immune system cells
-roles in immunity, inflammation and hematopoiesis

Question 2

What cells do cytokines target?

Answer 2

-macrophage
-B cells
-effector T cells
-tumor cells
-plasma cells

Question 3

What are the types of cytokines?

Answer 3

-Interleukin 1
-Chemokines
-Hematoprotein
-Interferons
-Interleukin 17

Question 4

What are some of the cellular effects of Cytokines?

Answer 4

-pleiotropic (affect many different cells and receptors with different outcomes)
-redundant (different cytokines have the same effect)
-Cascade effect (stimulate production of other cytokines)

Question 5

What are interleukins?

Answer 5

-secrete and act on leukoctyes
-regulate growth/differentiation of hematopoietic cells

Question 6

What are Chemokines?

Answer 6

-cell migration (during development, immune response, inflammation and cancer)
-Chemokine receptors are GPCRs

Question 7

What are TNFs (Tumor Necrosis Factor)?

Answer 7

-released upon infection by macrophages (causes inflammation)
-ribbon structure

Question 8

What are Interferons?

Answer 8

-regulate signaling in cells that are infected
“interfere” with viral replication
-helical structure, three types (I,II, and III)

Question 9

What are the 6 types of cytokine receptors?

Answer 9

-Immunoglobulin (Ig) family (IL-1 and IL-18)
-Hemopoietic Growth Factor (type 1) (IL-2 and IL-6)
-Interferon (type 2) (IFN B and Y)
-Tumor necrosis factors (type 3) (TNF cytokines, CD40, CD27, CD30)
-G Protein-coupled receptors
-Interleukin-17 receptor (IL-17R) family (A-E)

Question 10

What are chemokines?

Answer 10

-subset of cytokines that direct migration of leukocytes to regions of infected tissue
-signal through GPCRs
-chemoattractant

Question 11

What is the concept of cross-reactivity?

Answer 11

-one cytokine receptor can recognize multiple different ligands

Question 12

What is role in cytokine signaling?

Answer 12

-Macrophage release of chemokines induces leukocyte migration

Question 13

What are the three types of Leukocytes?

Answer 13

-Granulocytes (innate immunity)
-Monocytes (innate immunity)
-Lymphocytes (adaptive immunity)

Question 14

What is the role of CXCL8?

Answer 14

-recruits neutrophils (granulocyte; innate) from the blood and guides them to the infected tissue

Question 15

What is the role of TNFa?

Answer 15

-in the TNF receptor family
receptors: TNFR1 (expressed on most cell types; pro-inflammatory and apoptotic) TNFR2 (endothelial, epithelial and some immune cells; anti-inflammaotry and promotes cell survival and proliferation)
-released by lymphocytes and monocytes when infection is detected
-can induce fever, apoptosis and inflammation

Question 16

What do cytokines that recognize the gamma chain do?

Answer 16

-activate three major signaling pathways that promote cellular survival and proliferation
-PI3K/Akt pathway (anti-apoptotic)
-JAK-STAT pathway
-RAS-MAPK pathway
-serve as critical regulators of development, survival, proliferation, differentiation and/or function of multiple immune cell types

Question 17

What does the IL-6 signaling pathway do?

Answer 17

-important for T-cell differentiation and proliferation; B cell differentiation into plasma cells
-stimulates acute-phase protein synthesis, survival, proliferation, production of neutrophils, regulates inflammation

Question 18

What are some drugs against the IL-6 receptor?

Answer 18

TOCILIZUMAB and SARILUMAB, SILTUXIMAB
-antibodies that are against IL-6

Question 19

What are some qualities associated with IL-1?

Answer 19

-IL-1a and IL-1B forms
-master regulator of inflammation in innate immune response
-drugs developed against it (anakinra; Canakinumab; Rilonacept)

Question 20

What are some qualities associated with IL-17?

Answer 20

-pro-inflammatory immune responses; beneficial against infection from bacteria and fungi
-drug against it (Secukinumab)

Question 21

What are some qualities associated with Heterotrimeric G-proteins that couple to GPCRs

Answer 21

-three subunits (alpha, beta, gamma)
-Ga has GTPase activity
Ga can dissociate from By complex which stimulates/represses a particular effector protein

Question 22

What are the 4 types of a-subunits?

Answer 22

ai- inhibitory (inhibits cAMP)
as- stimulatory (increases cAMP)
aq- Phospholipase C
a12- Rho GEFs (activates Rho-family GTPases)

Question 23

What happens in GPCR signal termination?

Answer 23

1. Phosphorylation by G protein-coupled receptor kinases (GRK)
2. Binding of B-arrestin - desensitization
3. Recruitment to Clathrin-coated pits - internalization
4. Recycling or degradation
5. arrestin can also mediate intracellular signaling

Question 24

What does Adenylate cyclase do?

Answer 24

-catalyzes conversion of ATP to cAMP
-part of Gs and Gi and cAMP-mediated signaling
cAMP is a second messenger with numerous signaling roles