ABCMdb

ABCC7 p.Ser573Cys

CF databases:	c.1718C>G , p.Ser573Cys (CFTR1) ? , c.1718C>T , p.Ser573Phe (CFTR1) ? ,
Predicted by SNAP2:	A: N (82%), C: D (63%), D: N (72%), E: N (57%), F: D (85%), G: N (72%), H: D (80%), I: D (80%), K: D (59%), L: D (80%), M: D (80%), N: N (72%), P: D (59%), Q: N (61%), R: D (85%), T: N (78%), V: D (75%), W: D (91%), Y: D (85%),
Predicted by PROVEAN:	A: N, C: D, D: N, E: N, F: D, G: N, H: N, I: D, K: N, L: D, M: D, N: N, P: N, Q: N, R: D, T: N, V: D, W: D, Y: D,

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[hide] Identification of CFTR, PRSS1, and SPINK1 mutation... Pancreas. 2006 Oct;33(3):221-7. Keiles S, Kammesheidt A
Identification of CFTR, PRSS1, and SPINK1 mutations in 381 patients with pancreatitis.
Pancreas. 2006 Oct;33(3):221-7., [PMID:17003641]

Abstract [show]
OBJECTIVES: Chronic pancreatitis is a progressive inflammatory disorder leading to irreversible exocrine and/or endocrine impairment. It is well documented that mutations in the cationic trypsinogen (PRSS1) gene can cause hereditary pancreatitis. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) and the serine protease inhibitor Kazal type 1 (SPINK1) genes are also associated with pancreatitis. METHODS: We analyzed 381 patients with a primary diagnosis of chronic or recurrent pancreatitis using the Ambry Test: Pancreatitis to obtain comprehensive genetic information for the CFTR, SPINK1, and PRSS1 genes. RESULTS: The results identified 32% (122/381) of patients with 166 mutant CFTR alleles, including 12 novel CFTR variants: 4375-20 A>G, F575Y, K598E, L1260P, G194R, F834L, S573C, 2789 + 17 C>T, 621+83 A>G, T164S, 621+25 A>G, and 3500-19 G>A. Of 122 patients with CFTR mutations, 5.5% (21/381) also carried a SPINK1 mutation, and 1.8% (7/381) carried a PRSS1 mutation. In addition, 8.9% (34/381) of all patients had 1 of 11 different SPINK1 mutations. Another 6.3% (24/381) of the patients had 1 of 8 different PRSS1 mutations. Moreover, 1.3% of the patients (5/381) had 1 PRSS1 and 1 SPINK1 mutation. A total 49% (185/381) of the patients carried one or more mutations. CONCLUSIONS: Comprehensive testing of the CFTR, PRSS1, and SPINK1 genes identified genetic variants in nearly half of all subjects considered by their physicians as candidates for genetic testing. Comprehensive test identified numerous novel variants that would not be identified by standard clinical screening panels.

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4 Results: The results identified 32% (122/381) of patients with 166 mutant CFTR alleles, including 12 novel CFTR variants: 4375-20 A9G, F575Y, K598E, L1260P, G194R, F834L, S573C, 2789 +17 C9T, 621+83 A9G, T164S, 621+25 A9G, and 3500-19 G9A. Login to comment
71 Patients With 1 CFTR Mutation CFTR Mutation 1 No. of Patients 1717-1 G9A 1 2789+5 G9A 1 3849+10kb C9T 2 3849+45 G9A 1 621+3 A9G 2 A1364V 1 A349V 1 A455E 1 D1152H 1 D1445N 1 deltaF508 16 E217G 1 F1286C 1 F316L 1 G542X 1 G551D 1 I148T 1 I807M 1 L206W 1 L967S 2 L997F 2 P55S 1 Q179K 1 Q220X 1 R117H 3 R1453W 1 R297Q 1 R31C 1 R668C 2 S1235R 1 S573C 1 S945L 1 V562A 1 V754M 2 Y1092X 1 Total patients 58 MutationsinboldfacewouldnothavebeendetectedbytheACOG/ACMGmutationpanel. Login to comment
87 S573C A Hispanic male undergoing a diagnostic pancreatitis panel has a C9G transversion at nucleotide position 1850. Login to comment

[hide] Metformin treatment of diabetes mellitus increases... Cell Physiol Biochem. 2010;25(4-5):389-96. Epub 2010 Mar 23. Kongsuphol P, Cassidy D, Romeiras F, Schreiber R, Mehta A, Kunzelmann K
Metformin treatment of diabetes mellitus increases the risk for pancreatitis in patients bearing the CFTR-mutation S573C.
Cell Physiol Biochem. 2010;25(4-5):389-96. Epub 2010 Mar 23., [PMID:20332619]

Abstract [show]
Metformin use in diabetes can cause acidosis and might be linked to pancreatitis. Here, we mechanistically focus on this relationship via a point mutation in the cystic fibrosis transmembrane conductance regulator (CFTR; ABCC7). CFTR is an ATP-hydrolyzing, cAMP/PKA-activated anion channel regulating pancreatic bicarbonate/chloride secretion across duct-facing apical membranes in epithelia. CFTR has two nucleotide binding domains (NBD1/2) which clamp two ATP molecules across their opposed, inverted interfacial surfaces which generates anion-conductance after ATP hydrolysis. Notably, CFTR mutations not causal for classical cystic fibrosis segregate with unexplained pancreatitis and one of these lies in NBD1 near its ATP-clamp (S573C; close to the Walker B aspartate D572). We recently showed that after raising [cAMP], wt-CFTR chloride-conductance, when expressed in Xenopus oocytes, remains elevated despite the presence of metformin. Yet here, we find that S573C-CFTR manifests a metformin-inhibitable whole cell chloride-conductance after cAMP elevation. In the absence of metformin, cAMP-activated S573C-CFTR also displays a reduced anion-conductance relative to wt-CFTR. Furthermore, intra-oocyte acidification inhibited wt-CFTR and abolished S573C-CFTR conductance. We conclude that defective S573C-CFTR remains both poorly conducting and inhibited by metformin and intracellular acidosis. This might explain the propensity to pancreatitis with this rare CF mutation.

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1 Dr. Karl Kunzelmann Department of Physiology, University of Regensburg Universitätsstraße 31, 93053 Regensburg (Germany) Tel. +49 941 943-4302, Fax +49941 943-4315 E-Mail karl.kunzelmann@vkl.uni-regensburg.de Key Words Cystic fibrosis transmembrane conductance regulator • CFTR AMP • PKA AMP-activated protein kinase • S573C • Pancreatitis • Metformin • Pancreas • Chloride secretion Abstract Metformin use in diabetes can cause acidosis and might be linked to pancreatitis. Login to comment
5 Notably, CFTR mutations not causal for classical cystic fibrosis segregate with unexplained pancreatitis and one of these lies in NBD1 near its ATP-clamp (S573C; close to the Walker B aspartate D572). Login to comment
7 Yet here, we find that S573C-CFTR manifests a metformin-inhibitable whole cell chloride-conductance after cAMP elevation. Login to comment
8 In the absence of metformin, cAMP-activated S573C-CFTR also displays a reduced anion-conductance relative to wt-CFTR. Login to comment
9 Furthermore, intra-oocyte acidification inhibited wt-CFTR and abolished S573C-CFTR conductance. Login to comment
10 We conclude that defective S573C-CFTR remains both poorly conducting and inhibited by metformin and intracellular acidosis. Login to comment
39 We investigated the S573C point mutation that lies within the first nucleotide binding domain of CFTR adjacent to the Walker B aspartate at D572. Login to comment
40 S573C appears not to induce classical CF but instead segregates with pancreatitis of unknown etiology [20, 21]. Login to comment
41 We tested the hypothesis that this was merely a chance finding by investigating S573C-CFTR function. Login to comment
44 We speculated that the presence of the CFTR gene variant S573C in non-CF diabetes patients renders them more susceptible towards the development of pancreatitis and tested the potential role of metformin. Login to comment
45 We therefore examined the function of S573C and other point mutants of CFTR at this site by overexpression in Xenopus oocytes. Login to comment
46 The data indicate a lower channel activity of S573C-CFTR with a higher sensitivity towards metformin-induced closure. Login to comment
47 Impaired Cl-channel function and regulatory function of S573C-CFTR may explain the higher incidence of this mutant in patients with pancreatitis. Login to comment
48 Materials and Methods cRNAs for CFTR and double electrode voltage clamp Oocytes were injected with cRNA (10 ng, 47 nl double-distilled water) encoding wtCFTR, S573C-CFTR, and S573A-CFTR. Login to comment
60 Results S573C attenuates CFTR whole cell Cl-conductance and is inhibited by metformin Because S573C-CFTR has been found in patients with pancreatitis, we examined the ability of both wtCFTR and S573C-CFTR to generate Cl- currents by maximal stimulation of Xenopus oocytes with IBMX (1 mM) and forskolin (2 µM). Login to comment
61 Under these conditions which elevate cAMP and activate PKA, whole cell currents and conductances produced by S573C-CFTR were reduced (~20%) when compared to those produced by wt-CFTR (Fig. 1A-D).AMP-activated protein kinase (AMPK) has been shown previously to inhibit CFTR and to be relevant in vivo [13, 14, 22, 23]. Login to comment
64 Metformin only inhibited S573C-CFTR but not wt-CFTR (compare second bars in Fig. 1 E,F), in contrast to the more potent activator of AMPK, phenformin that inhibited both S573C-CFTR and wt-CFTR (Fig. 1E,F). Login to comment
66 S573C attenuates CFTR whole cell Cl-conductance. Login to comment
67 Current recordings obtained in Xenopus oocytes expressing wt-CFTR (A) or S573C-CFTR (B) showing activation of whole cell Cl- currents by stimulation with IBMX (1 mM) and forskolin (2 µM). Login to comment
69 Summaries of whole cell conductances activated by IBMX and forskolin (GI/F ) in ooctyes expressing wt-CFTR (E) and S573C-CFTR (F), and effects of the activators of AMPK metformin (Met; 2 mM) and phenformin (Phen; 5 mM) or the AMPK-inhibitor compound C (CC; 80 µM). Login to comment
75 Under these conditions it became quite obvious that S573C-CFTR has a reduced Cl-conductance compared to wtCFTR (Fig. 2C,D) and that 500 µM metformin did not inhibit wtCFTR and yet inhibited S573C-CFTR by about 25% (Fig. 2E), thus confirming the enhanced sensitivity of S573C-CFTR for inhibition by metformin. Login to comment
77 Since S573 is located in the first nucleotide binding domain (NBD1) of CFTR and because inhibition by the AMPK-activator metformin is enhanced for S573C-CFTR, the present results suggest that NBD1 may contribute to regulation of CFTR byAMPK. Login to comment
80 Metformin inhibits S573C-CFTR but not wt-CFTR. Login to comment
81 Current recordings obtained in a Xenopus oocyte expressing wt-CFTR (A) or S573C-CFTR (B) showing activation of whole cell Cl- currents by stimulation with only forskolin (20 µM). Login to comment
83 Summaries of the ration of whole cell conductances activated in the presence of metformin or under control conditions in oocytes expressing wt-CFTR and S573C-CFTR (E). Login to comment
95 We interpreted this data to suggest that the S573C defect might lie downstream of AMPK due to perturbation of the milieu around either the adjacent Walker B aspartate (for example at D572) or near another local cysteine, as suggested by Chen et al during their pH studies [24]. Login to comment
101 Acidification equally inhibits wtCFTR, S573A-CFTR and S573C-CFTR. Login to comment
106 Surprisingly, metformin (500 µM), when applied in the presence of acidic pH (pH 5.5), did not inhibit forskolin (20 µM) activated Cl- currents, generated by wt-CFTR, S573C-CFTR, or S573A-CFTR (Fig. 4C). Login to comment
107 Thus the S573C CFTR which had previously retained metformin-induced inhibition despite the presence of forskolin and IBMX, had now 'become wild type` just like S573A. Login to comment
108 We further tested whether intracellular acidification differentially affects whole cell currents produced by wt-CFTR, S573C-CFTR, or S573A-CFTR. Login to comment
114 Summary of the whole cell conductances generated by wt-CFTR, S573C-CFTR and S573A-CFTR when activated by forskolin (20 µM) in the presence of pH 5.5, and effects of metformin (500 µM) (C). Login to comment
116 CFTR by forskolin (20 µM) in the presence of CCCP and at physiological pH (pH 7.5), while activation of S573C-CFTR was largely reduced (Fig. 5A-C). Login to comment
117 Subsequent, acidification inhibited Cl- currents produced by wt-CFTR, S573C-CFTR, or S573A-CFTR, while subsequent alkalinization did not affect whole cell Cl- currents (Fig. 5A-C). Login to comment
118 In fact acidosis completely inhibited S573C-CFTR currents. Login to comment
119 Taken together the present results are consistent with a model whereby the S573C-CFTR mutation predisposes to pancreatitis because it i) may sensitize CFTR towards inappropriate regulation by AMPK, ii) is inhibited by the therapeutic biguanide metformin and iii) is inhibited potently by acidification. Login to comment
123 Inhibition of wtCFTR, S573C-CFTR, and S573 A-CFTR by intracellular acidosis. Login to comment
124 Current recordings obtained in a Xenopus oocyte expressing wt-CFTR (A), S573C-CFTR (B), or S573 A-CFTR (C). Login to comment
126 Acidification (pH 5.5, pH 6.5) but not alkalinization (pH 8.5) inhibits Cl- currents generated by wt-CFTR, S573C-CFTR and S573 A-CFTR. Login to comment
127 Acidosis completely inhibited currents produced by S573C-CFTR and S573A-CFTR. Login to comment
138 The result of the present study pose challenging new questions with respect to the molecular mechanisms for predisposal of S573C towards AMPK- phosphorylation, the residues within NBD1 that are phosphorylated byAMPK, and how S573C within NBD1 affects pH sensitivity of CFTR. Login to comment

[hide] Diagnostic testing by CFTR gene mutation analysis ... J Mol Diagn. 2005 May;7(2):289-99. Schrijver I, Ramalingam S, Sankaran R, Swanson S, Dunlop CL, Keiles S, Moss RB, Oehlert J, Gardner P, Wassman ER, Kammesheidt A
Diagnostic testing by CFTR gene mutation analysis in a large group of Hispanics: novel mutations and assessment of a population-specific mutation spectrum.
J Mol Diagn. 2005 May;7(2):289-99., [PMID:15858154]

Abstract [show]
Characterization of CFTR mutations in the U.S. Hispanic population is vital to early diagnosis, genetic counseling, patient-specific treatment, and the understanding of cystic fibrosis (CF) pathogenesis. The mutation spectrum in Hispanics, however, remains poorly defined. A group of 257 self-identified Hispanics with clinical manifestations consistent with CF were studied by temporal temperature gradient electrophoresis and/or DNA sequencing. A total of 183 mutations were identified, including 14 different amino acid-changing novel variants. A significant proportion (78/85) of the different mutations identified would not have been detected by the ACMG/ACOG-recommended 25-mutation screening panel. Over one third of the mutations (27/85) occurred with a relative frequency >1%, which illustrates that the identified mutations are not all rare. This is supported by a comparison with other large CFTR studies. These results underscore the disparity in mutation identification between Caucasians and Hispanics and show utility for comprehensive diagnostic CFTR mutation analysis in this population.

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89 This would result in premature termination of translation, which is known to result in CF, presumably as a result of nonsense-mediated mRNA decay or dysfunctionally shortened protein products.20 Promising effects of gentamicin treatment on CFTR expression may enhance targeted treatment in patients with these mutations.21 S573C A 9-year-old boy with pancreatitis has a CϾG transversion at nucleotide position 1850. Login to comment
91 This mutation in exon 12 substitutes a cysteine for serine at amino acid position 573. Login to comment
102 Novel Variants Detected in 257 Hispanic Patients Patient Novel variant 1 Other variants Age and symptoms 1 1429del7bp G542X Newborn with intestinal blockage 2 S573C None 9 years old, pancreatitis, limited clinical history 3 Y913X deltaF508/I1027T 1 month old, vomiting, weight loss, diarrhea 4 E588V deltaF508/R1438W Identified one time in a family, family studies revealed deltaF508 and R1438W are in cis 5 E588V G542X Newborn with pneumonia and sweat chloride of 59 mmol/L 6 P439S R668C 10 years old with mild CF symptoms; another patient with CBAVD has P439S/R334W 7 T604S deltaF508 1 month old 8 874insTACA deltaF508 Newborn with meconium ileus and IUGR 9 2585delT deltaF508/I1027T 13 years old with CF 10 1811 ϩ 1 G to A None 44 years old with positive sweat chloride; also seen in 5-year-old CF patient with 3821delT mutation 11 I285F None 1 year old with chronic respiratory problems, also carries a silent mutation at A455 12 P1372L None 1 month old, rule out CF 13 3271 ϩ 8 A to G None 16 years old, borderline sweat test 14 1341 ϩ 80 G to A None Recurrent sinusitis 15 1525 - 42 G to A None Two patients, one 9 years old with FTT, and one 18 months old with chronic lung disease, pulmonary hypotension, hypoxia CBAVD, congenital bilateral absence of the vas deference; IUGR, intrauterine growth retardation. Login to comment
186 Table 3. Continued CFTR mutations Alleles Relative mutation frequency (%) (of 317) G567A 1 Ͻ1 S573C 1 Ͻ1 E585X 1 Ͻ1 T604S 1 Ͻ1 F693L 1 Ͻ1 V754 mol/L 1 Ͻ1 2108delA 1 Ͻ1 2184delA 1 Ͻ1 2215insG 1 Ͻ1 2585delT 1 Ͻ1 2752 - 6TϾC 1 Ͻ1 E831X 1 Ͻ1 D836Y 1 Ͻ1 Y913X 1 Ͻ1 S945L 1 Ͻ1 L967S 1 Ͻ1 3171delC 1 Ͻ1 3199del6 1 Ͻ1 3271 ϩ 8AϾG 1 Ͻ1 R1066H 1 Ͻ1 R1070W 1 Ͻ1 Y1092X 1 Ͻ1 W1098C 1 Ͻ1 3500 - 2AϾT 1 Ͻ1 4016insT 1 Ͻ1 4374 ϩ 13AϾG 1 Ͻ1 D1152H 1 Ͻ1 R1158X 1 Ͻ1 R1162X 1 Ͻ1 W1282X 1 Ͻ1 N1303K 1 Ͻ1 Q1313X 1 Ͻ1 P1372L 1 Ͻ1 R1438W 1 Ͻ1 Total 317 100 Table 3. Login to comment