Epithelial Chloride Channel 4

Question 1

First CFTR KO mouse

Answer 1

1992 - Beverly Koller

3 groups

Question 2

Gabriel et al 1993

Answer 2

CFTR and ORCCs distinct proteins in regulatory relationship

Question 3

Gabriel 1993 findings - ORCCs and CFTR

Answer 3

KO mice lacking CF gene express ORCCs
PKA only activates ORCCS in CFTR expressing cells
CFTR involved in regulating ORCCs by PKA

Question 4

1995 Jovov

Answer 4

CFTR and ORCCs

Question 5

Explain Jovov 1995

Answer 5

CFTR and ORCC immunopurified from bovine trachea
planar lipid bilayers
nonfunctional mutant –> functional mutant
CFTR needed for OCC activation by ATP and PKA

Question 6

Smith 1996

Answer 6

airway surface liquid bacteriacidal

pseudomonas aeruginosa bacteria killed in normal but thrive in CF airway

Question 7

epithelial human b defensins

Answer 7

1 and 2

important natural bacteriacidal agents

Question 8

HBD1 and 2 - Singh et al 1998 findings

Answer 8

present in normal and CF
HBD activity dependent on ionic strength of medium
If NaCl high then reduction in killing

Question 9

singh et al 1998 lysosymes

Answer 9

in saliva - also affected by salts but not by non-ionic osmolytes
charge important

Question 10

which HBD particularly affected by NaCl conc?

Answer 10

1

Question 11

thiocyanate

Answer 11

sodium iodide transporter in basolateral membrane
exit via CFTR
important in bacteriacidal action

Question 12

Conner et al 2006

Answer 12

thiocyanate (-ve)
duox enzyme thiocyanate –> hypothiocyanate
reduced SCN transport by CFTR impairs lypoxygenase mediated bacteriacidal action

Question 13

thiocyanate or hypothiocyanate bacteriacidal?

Answer 13

hypothiocyanate

Question 14

Type 1 CFTR defect and therapy

Answer 14

protein production
gentamicin - suppress premature termination of transcription
read through compounds

Question 15

Type 2 CFTR defect and therapy

Answer 15

Processing

CFTR chaperones - stabilise protein structure/promote folding - expression in apical membrane

Question 16

Type 3 CFTR defect and therapy

Answer 16

Regulation
CFTR activators : flavinoids, alkylxanthines prevent cAMP breakdown
MBP derivatives

Question 17

what kind of defect is dF505?

Answer 17

type 2 - processing

Question 18

type 4 defect and therapy

Answer 18

conduction

CFTR potentiators: VX 770

Question 19

What is vx770?

Answer 19

Ivacaftor

Question 20

MPB-07 - Becq 1999

Answer 20

measure Isc over time
apply cpt-cAMP increase in secretion
glibenclamide inhibits CFTR bring current down - normal
MPB-07 = increase in current, similar to levels with cAMP - activate CFTR

Question 21

MPB-07 Iodine channels CFTR

Answer 21

iodine efflux only with MPB-07 not IBMX

getting deltaF508 to the membrane - chaperone aswell as an activator

Question 22

Pedemonte 2005

Answer 22

amiloride then FSK - not much in deltaF508

lower temperature FSK has more effect

Question 23

amiloride

Answer 23

KO sodium channels Enac

Question 24

FSK

Answer 24

activates adenylate cyclase then cAMP

Question 25

Van Groor et al 2009

Answer 25

rat thyroid cells
FSK not much effect
VX770 big effect on Isc - activity through CFTR

Question 26

Van Groor et al 2009 dF508 and G551D

Answer 26

FSK does little
VX770 substantial increase in current in human bronchial epithelium
G551D at membrane, better even though not at membrane

Question 27

Orkambi

Answer 27

Ivacaftor - VX770
Lumacaftor - VX809
licensed UK 2015 deltaF508 CFTR +/+
>£100, 000/year
approved NHS in 2019

Question 28

lumacaftor

Answer 28

CFTR chaperone and corrector

Question 29

CF airway and ENaC

Answer 29

increased sodium conductance in apical membrane
CFTR inhibits Enac in airway
in CF –> airway surface dehydration water follows

Question 30

CFTR and Enac in sweat duct

Answer 30

CFTR activate Enac in sweat duct

absence of CFTR in CF - salty sweat

Question 31

last 4 amino acids at c terminus of CFTR

Answer 31

aspartic acid, threonine, arginine, leucine

Question 32

what do 4 amino acids at c terminus of CFTR bind?

Answer 32

PDZ proteins

Question 33

PDZ proteins

Answer 33

PSD-95, zo-1, Dlg

apical localisation of CFTR?