Key points are not available for this paper at this time.
Accumulating evidence suggests that protein-protein interactions play an important role in transepithelial ion transport. In the present study, we report on the biochemical and functional association between cystic fibrosis transmembrane conductance regulator (CFTR) and a PDZ domain-containing protein Shank2. Exploratory reverse transcription-PCR screening revealed mRNAs for several members of PDZ domain-containing proteins in epithelial cells. Shank2, one of these scaffolding proteins, showed a strong interaction with CFTR by yeast two-hybrid assays. Shank2-CFTR interaction was verified by co-immunoprecipitation experiments in mammalian cells. Notably, this interaction was abolished by mutations in the PDZ domain of Shank2. Protein phosphorylation, HCO3- transport and Cl- current by CFTR were measured in NIH 3T3 cells with heterologous expression of Shank2. Of interest, expression of Shank2 suppressed cAMP-induced phosphorylation and activation of CFTR. Importantly, loss of Shank2 by stable transfection of antisense-hShank2 plasmid strongly increased CFTR currents in colonic T84 cells, in which CFTR and Shank2 were natively expressed. Our results indicate that Shank2 negatively regulates CFTR and that this may play a significant role in maintaining epithelial homeostasis under normal and diseased conditions such as those presented by secretory diarrhea. Accumulating evidence suggests that protein-protein interactions play an important role in transepithelial ion transport. In the present study, we report on the biochemical and functional association between cystic fibrosis transmembrane conductance regulator (CFTR) and a PDZ domain-containing protein Shank2. Exploratory reverse transcription-PCR screening revealed mRNAs for several members of PDZ domain-containing proteins in epithelial cells. Shank2, one of these scaffolding proteins, showed a strong interaction with CFTR by yeast two-hybrid assays. Shank2-CFTR interaction was verified by co-immunoprecipitation experiments in mammalian cells. Notably, this interaction was abolished by mutations in the PDZ domain of Shank2. Protein phosphorylation, HCO3- transport and Cl- current by CFTR were measured in NIH 3T3 cells with heterologous expression of Shank2. Of interest, expression of Shank2 suppressed cAMP-induced phosphorylation and activation of CFTR. Importantly, loss of Shank2 by stable transfection of antisense-hShank2 plasmid strongly increased CFTR currents in colonic T84 cells, in which CFTR and Shank2 were natively expressed. Our results indicate that Shank2 negatively regulates CFTR and that this may play a significant role in maintaining epithelial homeostasis under normal and diseased conditions such as those presented by secretory diarrhea. Secretory epithelia perform vectorial transport of salt and water molecules by coordinated actions of the transporters expressed in polarized epithelial membranes. One of the key membrane proteins regulating overall fluid movements is the cystic fibrosis transmembrane conductance regulator (CFTR), 1The abbreviations used are: CFTR, cystic fibrosis transmembrane conductance regulator; CF, cystic fibrosis; NBC, Na+-HCO3- cotransporter; NHE3, Na+/H+ exchanger 3; PDZ, PSD-95/discs large/ZO-1; PSD, postsynaptic density; RT, reverse transcription; aa, amino acid(s); DMEM, Dulbecco’s modified Eagle’s medium; IP, immunoprecipitation; BCECF-AM, 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein-acetoxymethyl ester; GKAP, guanylate kinase-associated protein. which itself has an anion-transporting activity (1Anderson M.P. Rich D.P. Gregory R.J. Smith A.E. Welsh M.J. Science. 1991; 251: 679-682Crossref PubMed Scopus (460) Google Scholar, 2Lee M.G. Wigley W.C. Zeng W. Noel L.E. Marino C.R. Thomas P.J. Muallem S. J. Biol. Chem. 1999; 274: 3414-3421Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar, 3Schwiebert E.M. Benos D.J. Egan M.E. Stutts M.J. Guggino W.B. Physiol. Rev. 1999; 79: S145-S166Crossref PubMed Scopus (383) Google Scholar). Aberrant membrane transport caused by either hypo- or hyper-functioning of CFTR, can be detrimental, and may result in life-threatening diseases, such as cystic fibrosis or secretory diarrhea (4Quinton P.M. Physiol. Rev. 1999; 79: S3-S22Crossref PubMed Scopus (317) Google Scholar, 5Kunzelmann K. Mall M. Physiol. Rev. 2002; 82: 245-289Crossref PubMed Scopus (544) Google Scholar). Therefore, the fine regulation of salt and water transport is essential in epithelial and body homeostasis. Accumulating evidence suggests that protein-protein interaction performs an important role in the regulation of transepithelial ion transport (6Kunzelmann K. News Physiol. Sci. 2001; 16: 167-170PubMed Google Scholar). Clustering of ion transporters and associated proteins in microdomains of polarized epithelia can facilitate the effective secretion or absorption of salt and water molecules. In this regard, modular adaptor proteins such as PDZ (PSD-95/discs large/ZO-1) domain-containing proteins have drawn increasing attention due to their ability to form supramolecular complexes (7Sheng M. Sala C. Annu. Rev. Neurosci. 2001; 24: 1-29Crossref PubMed Scopus (1054) Google Scholar). We have previously shown that the regulatory interaction between CFTR and Na+/H+ exchanger 3 (NHE3) through PDZ-based scaffolds is essential for the coordinated regulation of pancreatic bicarbonate secretion (8Ahn W. Kim K.H. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Lee M.G. J. Biol. Chem. 2001; 276: 17236-17243Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar). In addition, it was found that a number of membrane transporters and receptors participating in pancreatic fluid formation, such as Na+-HCO3- cotransporters (NBC), purinergic receptors, and secretin receptors have a PDZ-binding motif on their C terminus (9Lee M.G. Ahn W. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Kim K.H. J. Pancreas. 2001; 2: 203-206Google Scholar, 10Park M. Ko S.B. Choi J.Y. Muallem G. Thomas P.J. Pushkin A. Lee M.S. Kim J.Y. Lee M.G. Muallem S. Kurtz I. J. Biol. Chem. 2002; 277: 50503-50509Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar). Therefore, multiple protein interactions through PDZ-based scaffolds are believed to perform a critical role in fluid secretion by pancreatic epithelia and possibly by other CFTR-expressing epithelia. Recently, a large number of PDZ domain-containing proteins were identified in neuronal cells, especially in the postsynaptic density (PSD) of excitatory synapses. Although limited information is available up to now, in general, organization by PDZ-based scaffolds allows the stable localization of interacting proteins and enhances the rate and fidelity of signal transduction (7Sheng M. Sala C. Annu. Rev. Neurosci. 2001; 24: 1-29Crossref PubMed Scopus (1054) Google Scholar). Because both neurons and epithelia share many common features, such as ectodermal origin and polarized intracellular structures, it is predicted that some of these scaffolds are expressed in epithelial cells and that they mediate protein-protein interaction. In this study, we aimed to identify the PDZ domain-containing proteins expressed in secretory epithelia and to further characterize their roles in transepithelial ion transport using integrated molecular, biochemical, and physiological approaches. In an exploratory RT-PCR, it was found that pancreatic epithelia express the mRNAs of several PDZ domain-containing proteins, including SAP97, PSD-95, and Shank2. Of these, Shank2, an isoform of the recently identified family of multimodular adaptors (11Sheng M. Kim E. J. Cell Sci. 2000; 113: 1851-1856Crossref PubMed Google Scholar), showed an association with CFTR through its PDZ domain in the yeast two-hybrid system and in the mammalian cells. Measurements in CFTR-expressing NIH 3T3 cells revealed that Shank2 overexpression suppressed the cAMP-induced phosphorylation and activation of CFTR. In addition, antisense-Shank2 treatment augmented the CFTR-dependent Cl- transport in T84 epithelial cells, in which CFTR and Shank2 are endogenously expressed. The above results indicate that Shank2 mediates inhibitory regulation of CFTR and that this may play an important role in epithelial homeostasis. Materials—The HA-tagged full-length pcDNA3.1-rShank2/CortBP1 construct has been described previously (12Park E. Na M. Choi J. Kim S. Lee J.R. Yoon J. Park D. Sheng M. Kim E. J. Biol. Chem. 2003; 278: 19220-19229Abstract Full Text Full Text PDF PubMed Scopus (143) Google Scholar). Rabbit polyclonal anti-Shank2 1136 sera were raised against the SAM region of Shank2. To generate H6 fusion proteins for immunization, aa 1012–1252 of rShank2 was amplified by PCR and subcloned into pRSETB (Invitrogen), and fusion proteins were purified using Probond resin (Invitrogen). The specificity of the Shank2 antibody was confirmed by immunoblotting on Shank isoforms expressed in heterologous cells as described previously (13Lim S. Naisbitt S. Yoon J. Hwang J.I. Suh P.G. Sheng M. Kim E. J. Biol. Chem. 1999; 274: 29510-29518Abstract Full Text Full Text PDF PubMed Scopus (235) Google Scholar). M3A7 monoclonal antibody against the NBD2 domain and 24-1 monoclonal antibody against the C terminus of CFTR were purchased from Upstate Biotechnologies and R 251: 679-682Crossref PubMed Scopus (460) Google Scholar) were kindly provided by Dr. Michael J. Welsh (University of Iowa, Iowa City, IA) and were maintained in Dulbecco’s modified Eagle’s medium containing 10 mm glucose and 10% fetal calf serum. For the stable expression of Shank2, NIH 3T3 cells were transfected with pcDNA3.1-rShank2 constructs and selected with G418. T84 cells originated from human colonic epithelia were purchased from the American Type Culture Collection (ATCC) and maintained in a 1:1 mixture of Ham’s F-12 medium and with fetal calf serum. yeast two-hybrid was as described E. M. A. Sheng M. PubMed Scopus Google Scholar). The yeast and under of the was used in the To the activity was by the of yeast on For containing the containing aa of the C terminus of membrane proteins were amplified by PCR and subcloned into and The constructs containing the PDZ of SAP97, PSD-95, and Shank2 were previously described (12Park E. Na M. Choi J. Kim S. Lee J.R. Yoon J. Park D. Sheng M. Kim E. J. Biol. Chem. 2003; 278: 19220-19229Abstract Full Text Full Text PDF PubMed Scopus (143) Google Scholar, E. M. A. Sheng M. PubMed Scopus Google Scholar, Kim S. Lee J.R. Yoon J. Kim E. J. Neurosci. 2002; PubMed Google Scholar). was using pancreatic and pancreatic cells as previously (8Ahn W. Kim K.H. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Lee M.G. J. Biol. Chem. 2001; 276: 17236-17243Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar). The used for this were as PCR PCR PCR PCR PCR PCR PCR PCR and from were in in and into of was as previously (8Ahn W. Kim K.H. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Lee M.G. J. Biol. Chem. 2001; 276: 17236-17243Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar). the were and by in for 10 were by for with of containing and the were by with anti-Shank2 1136 and with were with a and pancreatic or NIH 3T3 were with the and in complexes were by to protein and were with to The 10% and the mixture The or were in and by The proteins were to and the were by a in a containing The were with the and and protein were by The of were using was using with pcDNA3.1-rShank2 plasmid to the of rShank2 was with amino The were as and were and used for the PCR to generate with of Cl- were on CFTR-expressing NIH 3T3 cells they been stably transfected with pcDNA3.1-rShank2 or The and 10 and the 10 and 10 experiments were the CFTR was by were and using an system and a currents were as current of activity was measured by the intracellular in to of the as previously W. Lee J.A. Ahn W. W. Ahn Kim K.H. Lee M.G. J. Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar). the of the of due to intracellular of HCO3- were to a using the and expressed as were with and to form the of a The 10 and 10 NIH 3T3 cells were with a by for 10 in containing the cells were with a and was of and a of using a The containing 10 was with and were by Cl- with The were by the cells with containing mm 10 mm and with to of of CFTR was as described by M.P. A. M. E. J. Cell Biol. PubMed Scopus Google Scholar) with cells were with containing mm and mm and with 10 mm for in the to of to The cells were and using in for was with a mm 10 mm and with For cells were with for or and with a mm mm 10 mm with The were for 10 and the was was to the of protein in of and the mixture was with complexes were and proteins were in by and with the antibody of CFTR 3T3 cells in were in a with for 3 The cells were with and with the and the of for 10 The of were with M3A7 CFTR by and by for in T84 was expressed in T84 cells to human Shank2 The common of the identified of and the were selected as The were amplified by PCR and subcloned into in the reverse using the and The were as G. were selected using and the of Shank2 were confirmed by are presented as the of the number of The results of multiple experiments were using the or of as of PDZ-based in we that interactions between multiple membrane proteins, which have PDZ-binding motif on their C terminus perform important roles in pancreatic bicarbonate secretion (8Ahn W. Kim K.H. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Lee M.G. J. Biol. Chem. 2001; 276: 17236-17243Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar, M.G. Ahn W. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Kim K.H. J. Pancreas. 2001; 2: 203-206Google Scholar, 10Park M. Ko S.B. Choi J.Y. Muallem G. Thomas P.J. Pushkin A. Lee M.S. Kim J.Y. Lee M.G. Muallem S. Kurtz I. J. Biol. Chem. 2002; 277: 50503-50509Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar). Therefore, as an we the of PDZ domain-containing proteins in pancreatic epithelia by using as a shown in pancreatic expressed the mRNAs of SAP97, PSD-95, and Shank2. pancreatic cells by showed the of Shank2. a of guanylate kinase-associated protein was in from pancreatic The expression of Shank2 in pancreatic was further confirmed by Of interest, Shank2 was found to be in the of large and pancreatic expression was in the of pancreatic cells between PDZ-based and interactions between the C of membrane proteins in pancreatic epithelia and the PDZ of SAP97, PSD-95, and Shank2 were by the yeast two-hybrid of PDZ-binding motif of the membrane proteins are under To the of the protein activity was by the of yeast on medium with as were confirmed by the In the yeast two-hybrid Shank2 showed a strong association with CFTR, NHE3, and the membrane we CFTR for further CFTR is to perform a role in ion transport and to have regulatory on the other and (8Ahn W. Kim K.H. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Lee M.G. J. Biol. Chem. 2001; 276: 17236-17243Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar, 10Park M. Ko S.B. Choi J.Y. Muallem G. Thomas P.J. Pushkin A. Lee M.S. Kim J.Y. Lee M.G. Muallem S. Kurtz I. J. Biol. Chem. 2002; 277: 50503-50509Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar). To the interaction between CFTR and Shank2 in mammalian cells, CFTR-expressing NIH 3T3 cells were stably transfected with pcDNA3.1-rShank2 or with and experiments were shown in transfection of pcDNA3.1-rShank2 expression of Shank2 protein in NIH 3T3 cells Notably, large of CFTR proteins were in anti-Shank2 from cells experiments using in reverse the association between Shank2 and CFTR two-hybrid activity was by the of yeast on medium to the of protein-protein interactions between the PDZ of adaptor proteins and the C terminus of membrane the transfection with the and of yeast cells were on and The number of yeast on medium was by that of on medium and expressed as was used as was used as in a has been that the of the of PDZ domain in an important role in PDZ interaction by a strong between its and the of the of the Lee A. J. Kim E. Sheng M. Full Text Full Text PDF PubMed Scopus Google Scholar). To the of the in we with other amino containing and and with a amino and measured the protein-protein interaction by shown in interactions were abolished in and by and Therefore, it was that PDZ-based interactions are for of CFTR-dependent by is that CFTR protein has a Cl- (1Anderson M.P. Rich D.P. Gregory R.J. Smith A.E. Welsh M.J. Science. 1991; 251: 679-682Crossref PubMed Scopus (460) Google Scholar). the of CFTR-expressing NIH 3T3 cells were measured in the they been stably transfected with pcDNA3.1-rShank2 or with the a large current in with and treatment with this current by were in with of CFTR Cl- currents M.G. Wigley W.C. Zeng W. Noel L.E. Marino C.R. Thomas P.J. Muallem S. J. Biol. Chem. 1999; 274: 3414-3421Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar). Shank2 overexpression the CFTR current by Recently, it was found that CFTR an important role in transepithelial HCO3- transport by regulating M.G. Wigley W.C. Zeng W. Noel L.E. Marino C.R. Thomas P.J. Muallem S. J. Biol. Chem. 1999; 274: 3414-3421Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar, M.G. Choi J.Y. E. Thomas P.J. Muallem S. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). HCO3- secretion by CFTR-dependent HCO3- transport has been to be an important in and pancreatic J.Y. Muallem D. K. Lee M.G. Thomas P.J. Muallem S. 2001; PubMed Scopus Google Scholar, P.M. 2001; PubMed Scopus Google Scholar). Therefore, were measured in NIH 3T3 cells by the due to Cl- from M.G. Wigley W.C. Zeng W. Noel L.E. Marino C.R. Thomas P.J. Muallem S. J. Biol. Chem. 1999; 274: 3414-3421Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar), the of CFTR-expressing NIH 3T3 cells were increased by those of expressing cells were The and of CFTR-expressing NIH 3T3 cells were and respectively. In cells, activity was with transfected cells. to the results of Cl- Shank2 overexpression the in CFTR-expressing NIH 3T3 cells for the CFTR were to the of inhibitory of Shank2 on CFTR-dependent The the membrane expression of CFTR protein. Because Shank2 is to be associated with proteins (11Sheng M. Kim E. J. Cell Sci. 2000; 113: 1851-1856Crossref PubMed Google Scholar), it may or the of CFTR protein. proteins were and the and with M3A7 antibody In to Shank2 overexpression showed a to the membrane expression of CFTR by and to the of the CFTR protein from to of the the results of experiments the CFTR activity by Shank2. The of the CFTR activity be the cAMP-induced phosphorylation of CFTR Shank2 is that phosphorylation performs critical roles in CFTR activation D. A. J. 2001; PubMed Scopus Google Scholar). To the of phosphorylation, of CFTR protein was in NIH 3T3 cells in phosphorylation by with and with the CFTR immunoblotting was to that of CFTR protein were in In the phosphorylation of were with the in transfected cells, and the results of experiments are in Of Shank2 overexpression the cAMP-induced phosphorylation of CFTR as as the it was that the of CFTR activity by Shank2 was possibly due to the cAMP-induced phosphorylation of CFTR. in or of CFTR the epithelial homeostasis (4Quinton P.M. Physiol. Rev. 1999; 79: S3-S22Crossref PubMed Scopus (317) Google Scholar, 5Kunzelmann K. Mall M. Physiol. Rev. 2002; 82: 245-289Crossref PubMed Scopus (544) Google Scholar). the inhibitory regulation of Shank2 on CFTR, colonic epithelia be the to the physiological role of Shank2, hyper-functioning of CFTR life-threatening conditions such as K. Mall M. Physiol. Rev. 2002; 82: 245-289Crossref PubMed Scopus (544) Google Scholar, Stutts M.J. Science. PubMed Scopus Google Scholar). we the expression of Shank2 in colonic shown in Shank2 was expressed in colonic in of were in from colonic in those from the pancreatic possibly due to the of CFTR protein in the colonic The expression of Shank2 was by with anti-Shank2 and In general, colonic epithelia and cells K. Mall M. Physiol. Rev. 2002; 82: 245-289Crossref PubMed Scopus (544) Google Scholar). Shank2 was expressed in both and cells, CFTR was expressed in cells. was found in pancreatic epithelia Shank2 was in the of colonic epithelia. Therefore, in and in showed that Shank2 and CFTR were in the of cells To the of CFTR has physiological we to Shank2 from colonic T84 cells by stably antisense-hShank2 shown in antisense-Shank2 treatment caused an of in Shank2 protein expression in T84 cells. We the of Shank2 loss on CFTR activity by of the Cl- current a of is presented in a of T84 cells showed significant CFTR Cl- We the cells showed the current as and their for the of Shank2 The of cells was between the and the cells and by In the of cells was verified by Cl- by the Notably, loss of Shank2 by treatment augmented CFTR currents in T84 cells, in which Shank2 and CFTR are endogenously expressed. an current of a in transfected cells, and this was increased to in cells of from cells of are shown in treatment an current in with In addition, an of of this current by that of the currents were by CFTR. of proteins the microdomains of intracellular is that the to as as to form One of the critical of these protein complexes is the modular adaptor Recently, a family of PDZ-based adaptors has been identified by several and as or (11Sheng M. Kim E. J. Cell Sci. 2000; 113: 1851-1856Crossref PubMed Google Scholar, S. Kim E. Sala C. J. R.J. Sheng M. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar, J. J. 2002; PubMed Scopus Google Scholar). revealed that the Shank family of proteins has many especially in the of excitatory (12Park E. Na M. Choi J. Kim S. Lee J.R. Yoon J. Park D. Sheng M. Kim E. J. Biol. Chem. 2003; 278: 19220-19229Abstract Full Text Full Text PDF PubMed Scopus (143) Google Scholar). For Shank with and the and the receptors in neurons Naisbitt S. A. Sheng M. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). the results of present that the role of Shank as a is limited to the neuronal The in this is the of CFTR activity by Shank2. CFTR-dependent Cl- and were by Shank2 overexpression in CFTR-expressing NIH 3T3 cells 3 and In addition, cAMP-induced phosphorylation of CFTR was by Shank2 in the heterologous expression system C and Importantly, loss of Shank2 by treatment increased Cl- in colonic T84 cells, in which epithelial were the above that Shank2 has a inhibitory on the anion-transporting of CFTR. the that of CFTR life-threatening secretory Shank2 may play a significant role in the regulation of CFTR activity in colonic epithelia. to the experiments in T84 cells, we found that are of of CFTR activity between In we measured the CFTR Cl- activity in T84 cells from a from number showed the CFTR activity in of both the of cells and the of CFTR Cl- Therefore, stable transfection of antisense-Shank2 plasmid was to this of T84 cells and functional experiments were expression of CFTR protein in T84 cells the further that been in NIH 3T3 cells. Although the results in heterologous expression system with expression we that significant between these systems, expression of Shank2 CFTR activity in both NIH 3T3 and T84 cells. The that a protein can to CFTR and its activity is of the between and CFTR D.J. W. J. Benos D.J. PubMed Scopus Google Scholar). in several the inhibitory of Shank2 on CFTR is from that of For to the of CFTR and is believed to CFTR activity by the or by membrane of CFTR E. A. A. D.J. Sci. S. A. 2002; PubMed Scopus Google Scholar). the Shank2 to to the PDZ-binding motif of CFTR and and its by cAMP-induced phosphorylation The for the cAMP-induced phosphorylation are under is that Shank2 with a that can CFTR. the between Shank2 and scaffolds the C terminus of CFTR. For PDZ-based such as or have been to CFTR by protein phosphorylation or by D. A. Stutts M.J. Milgram S.L. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, M.J. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, S. Guggino W.B. M. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). Although the present showed that Shank2 CFTR phosphorylation this other for the CFTR For Shank2 has a PDZ it can the by multiple PDZ domain-containing scaffolds S. Guggino W.B. M. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). The between Shank2-CFTR and or may the regulation of CFTR. the yeast two-hybrid it was found that Shank2 can with and in to CFTR. Notably, of these transporters are in the membrane of pancreatic cells and in transepithelial HCO3- transport (8Ahn W. Kim K.H. Lee J.A. Kim J.Y. Choi J.Y. Moe O.W. Milgram S.L. Muallem S. Lee M.G. J. Biol. Chem. 2001; 276: 17236-17243Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar, 10Park M. Ko S.B. Choi J.Y. Muallem G. Thomas P.J. Pushkin A. Lee M.S. Kim J.Y. Lee M.G. Muallem S. Kurtz I. J. Biol. Chem. 2002; 277: 50503-50509Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar). In we that Shank2 to NHE3, and that the overexpression of Shank2 the cAMP-induced of activity in the heterologous expression system of cells that Shank2 as a common regulator for ion and fluid transport in the membrane of especially as a of the Shank family of proteins has multiple protein-protein interaction and is by multiple an a PDZ a and a motif domain in terminus to C terminus isoforms and of Shank showed a of in their domain (11Sheng M. Kim E. J. Cell Sci. 2000; 113: 1851-1856Crossref PubMed Google Scholar, S. Naisbitt S. Yoon J. Hwang J.I. Suh P.G. Sheng M. Kim E. J. Biol. Chem. 1999; 274: 29510-29518Abstract Full Text Full Text PDF PubMed Scopus (235) Google Scholar). Although the of Shank originated from domain and the form of found and used in this have or have the other including the PDZ for these modular may roles of Shank2 proteins in epithelial In we found that Shank2 to CFTR and the cAMP-induced activation of CFTR an integrated for PDZ-based scaffolds in epithelial Because CFTR especially hyper-functioning of CFTR life-threatening conditions such as diarrhea in the fine regulation of CFTR activity by Shank2 be important in maintaining epithelial and body homeostasis.
Kim et al. (Mon,) studied this question.