ABCMdb

ABCC7 p.Ser13Ala

ClinVar:	c.38C>T , p.Ser13Phe ? , not provided
CF databases:	c.38C>T , p.Ser13Phe (CFTR1) ? , This mutation was detected by DGGE and identified by direct sequencing in a CF patient of Sardinian origin.
Predicted by SNAP2:	A: D (95%), C: D (95%), D: D (95%), E: D (95%), F: D (63%), G: D (95%), H: D (95%), I: D (95%), K: D (95%), L: D (95%), M: D (95%), N: D (95%), P: D (95%), Q: D (95%), R: D (95%), T: D (95%), V: D (95%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	A: N, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: N, P: D, Q: D, R: D, T: N, V: D, W: D, Y: D,

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Publications
[hide] Direct interaction with filamins modulates the sta... J Clin Invest. 2007 Feb;117(2):364-74. Epub 2007 Jan 18. Thelin WR, Chen Y, Gentzsch M, Kreda SM, Sallee JL, Scarlett CO, Borchers CH, Jacobson K, Stutts MJ, Milgram SL
Direct interaction with filamins modulates the stability and plasma membrane expression of CFTR.
J Clin Invest. 2007 Feb;117(2):364-74. Epub 2007 Jan 18., [PMID:17235394]

Abstract [show]
The role of the cystic fibrosis transmembrane conductance regulator (CFTR) as a cAMP-dependent chloride channel on the apical membrane of epithelia is well established. However, the processes by which CFTR is regulated on the cell surface are not clear. Here we report the identification of a protein-protein interaction between CFTR and the cytoskeletal filamin proteins. Using proteomic approaches, we identified filamins as proteins that associate with the extreme CFTR N terminus. Furthermore, we identified a disease-causing missense mutation in CFTR, serine 13 to phenylalanine (S13F), which disrupted this interaction. In cells, filamins tethered plasma membrane CFTR to the underlying actin network. This interaction stabilized CFTR at the cell surface and regulated the plasma membrane dynamics and confinement of the channel. In the absence of filamin binding, CFTR was internalized from the cell surface, where it prematurely accumulated in lysosomes and was ultimately degraded. Our data demonstrate what we believe to be a previously unrecognized role for the CFTR N terminus in the regulation of the plasma membrane stability and metabolic stability of CFTR. In addition, we elucidate the molecular defect associated with the S13F mutation.

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No. Sentence Comment
73 WT, S13F, and S13A CFTRs were transiently expressed in HEK293 cells, labeled, immunoprecipitated, and analyzed by autoradiography (Figure 2A). Login to comment
75 After 4 hours of chase, WT and S13A CFTRs were present almost exclusively as the mature band C, while no band C was observed for ΔF508 (Figure 2B). Login to comment
76 Like WT and S13A CFTR, S13F CFTR was clearly processed from the band B to band C protein during the first 4 hours of chase. Login to comment
79 The half-life was similar between WT and S13A CFTR (22.5 and 22.6 hours, respectively; Figure 2C). Login to comment
94 However, CFTR1-25/S13A peptides bound to FLNs similarly to the CFTR1-25 peptides (Figure 3B). Login to comment
96 Thus, the reduction relative to WT CFTR in the band B/band C ratio observed for the S13F mutation, but not the S13A mutation, correlates with the ability to bind FLN-A in vitro. Login to comment
101 Furthermore, FLN-A coprecipitated with WT and S13A CFTR expressed in HEK293 cells, but not with S13F CFTR (Figure 3E). Login to comment
113 S13A, CFTR1-25/S13A. Login to comment
125 The surface pool of CFTR was detected by immunofluorescence in unpermeabilized baby hamster kidney (BHK) cells expressing either WT, S13A, S13F, or ΔF508 HA-CFTR. Login to comment
126 We observed significant amounts of WT and S13A CFTR at the cell surface, while no signal was observed for ΔF508 (Figure 5A). Login to comment
128 Unlike ΔF508 CFTR, we observed surface staining for S13F CFTR; however, the staining was greatly reduced compared with WT and S13A CFTR. Login to comment
130 In agreement with our observations by immunofluorescence, a substantial pool of WT and S13A CFTR resided on the cell surface (41.2% and 37.8%, respectively), while no ΔF508 was observed (Figure 5B). Login to comment
207 Additionally, S13F was prematurely sorted to lysosomes, which may explain why mature S13F CFTR was degraded more rapidly than the WT protein. Therefore, we examined the half-life of WT, S13F, and S13A CFTR by pulse chase in the presence of the lysosomal protease inhibitor leupeptin. Login to comment
324 WT, S13F, S13A, and ΔF508 CFTRs were transiently expressed in HEK293 cells. Login to comment

[hide] Targeting autophagy as a novel strategy for facili... Autophagy. 2012 Nov 1;8(11). Luciani A, Villella VR, Esposito S, Gavina M, Russo I, Silano M, Guido S, Pettoello-Mantovani M, Carnuccio R, Scholte B, De Matteis A, Maiuri MC, Raia V, Luini A, Kroemer G, Maiuri L
Targeting autophagy as a novel strategy for facilitating the therapeutic action of potentiators on DeltaF508 cystic fibrosis transmembrane conductance regulator.
Autophagy. 2012 Nov 1;8(11)., [PMID:22874563]

Abstract [show]
Channel activators (potentiators) of cystic fibrosis (CF) transmembrane conductance regulator (CFTR), can be used for the treatment of the small subset of CF patients that carry plasma membrane-resident CFTR mutants. However, approximately 90% of CF patients carry the misfolded DeltaF508-CFTR and are poorly responsive to potentiators, because DeltaF508-CFTR is intrinsically unstable at the plasma membrane (PM) even if rescued by pharmacological correctors. We have demonstrated that human and mouse CF airways are autophagy deficient due to functional sequestration of BECN1 and that the tissue transglutaminase-2 inhibitor, cystamine, or antioxidants restore BECN1-dependent autophagy and reduce SQSTM1/p62 levels, thus favoring DeltaF508-CFTR trafficking to the epithelial surface. Here, we investigated whether these treatments could facilitate the beneficial action of potentiators on DeltaF508-CFTR homozygous airways. Cystamine or the superoxide dismutase (SOD)/catalase-mimetic EUK-134 stabilized DeltaF508-CFTR at the plasma membrane of airway epithelial cells and sustained the expression of CFTR at the epithelial surface well beyond drug withdrawal, overexpressing BECN1 and depleting SQSTM1. This facilitates the beneficial action of potentiators in controlling inflammation in ex vivo DeltaF508-CFTR homozygous human nasal biopsies and in vivo in mouse DeltaF508-CFTR lungs. Direct depletion of Sqstm1 by shRNAs in vivo in DeltaF508-CFTR mice synergized with potentiators in sustaining surface CFTR expression and suppressing inflammation. Cystamine pre-treatment restored DeltaF508-CFTR response to the CFTR potentiators genistein, Vrx-532 or Vrx-770 in freshly isolated brushed nasal epithelial cells from DeltaF508-CFTR homozygous patients. These findings delineate a novel therapeutic strategy for the treatment of CF patients with the DeltaF508-CFTR mutation in which patients are first treated with cystamine and subsequently pulsed with CFTR potentiators.

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Sentences [show]
No. Sentence Comment
108 We found that Vrx-770 was effective in stimulating the response to Fsk only when brushed nasal epithelial cells were pretreated with cystamine or EUK-134 (Fig. S13A). Login to comment
111 We found that Vrx-770 was effective in stimulating the response to Fsk only when brushed nasal epithelial cells were pretreated with cystamine or EUK-134 (Fig. S13A). Login to comment