ABCMdb

PMID: 19933268

Hosy E, Dupuis JP, Vivaudou M
Impact of disease-causing SUR1 mutations on the KATP channel subunit interface probed with a rhodamine protection assay.
J Biol Chem. 2010 Jan 29;285(5):3084-91. Epub 2009 Nov 20., [PubMed]

Sentences

No. Mutations Sentence Comment

4 ABCC8 p.Phe132Leu The activating mutation F132L in SUR1, which causes neonatal diabetes, also rendered the channel resistant to Rho block, suggesting that it stabilized an activated conformation by uncoupling TMD0 from the rest of SUR1. Login to comment 5 ABCC8 p.Glu128Lys At a nearby residue, the SUR1 mutation E128K impairs trafficking, thereby reducing surface expression and causing hyperinsulinism. Login to comment 98 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu These observations suggest that activation by distinct pathways converges toward the same Rho phenotype, which we have shown to reflect a particular conformation of the SUR/Kir6.2 interface. The Mutation F132L in SUR1 Induces a Rho-resistant Phenotype- The mutation F132L in TMD0 of SUR1 is responsible for neonatal diabetes (15). Login to comment 99 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu These observations suggest that activation by distinct pathways converges toward the same Rho phenotype, which we have shown to reflect a particular conformation of the SUR/Kir6.2 interface. The Mutation F132L in SUR1 Induces a Rho-resistant Phenotype- The mutation F132L in TMD0 of SUR1 is responsible for neonatal diabetes (15). Login to comment 100 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu These observations suggest that activation by distinct pathways converges toward the same Rho phenotype, which we have shown to reflect a particular conformation of the SUR/Kir6.2 interface. The Mutation F132L in SUR1 Induces a Rho-resistant Phenotype- The mutation F132L in TMD0 of SUR1 is responsible for neonatal diabetes (15). Login to comment 109 ABCC8 p.Phe132Leu In the same study, the F132L mutation was shown by co-immunoprecipitation to diminish FIGURE 1. Login to comment 110 ABCC8 p.Phe132Leu In the same study, the F132L mutation was shown by co-immunoprecipitation to diminish FIGURE 1. Login to comment 111 ABCC8 p.Phe132Leu In the same study, the F132L mutation was shown by co-immunoprecipitation to diminish FIGURE 1. Login to comment 118 ABCC8 p.Phe132Leu It remains that, when probed with the Rho protection assay, the F132L mutation had distinct effects on full-length SUR1 and on the isolated TMD0 domain. Login to comment 119 ABCC8 p.Phe132Leu It remains that, when probed with the Rho protection assay, the F132L mutation had distinct effects on full-length SUR1 and on the isolated TMD0 domain. Login to comment 120 ABCC8 p.Phe132Leu It remains that, when probed with the Rho protection assay, the F132L mutation had distinct effects on full-length SUR1 and on the isolated TMD0 domain. Login to comment 121 ABCC8 p.Phe132Leu In conclusion, the mutation F132L in SUR1 produces a Rho-resistant phenotype like the activators MgADP, zinc, or SR47063. Login to comment 122 ABCC8 p.Phe132Leu In conclusion, the mutation F132L in SUR1 produces a Rho-resistant phenotype like the activators MgADP, zinc, or SR47063. Login to comment 123 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu This suggests that the mutation F132L mimics the presence of openers and causes channel hyperactivity by inducing a conformational change that alters the TMD0/Kir6.2 interface. The Mutation E126A in SUR2A Induces a Rho-sensitive Phenotype-Residue Phe132 is located in the predicted second intracellular loop of SUR1 (24). Login to comment 124 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu Another residue of this short loop, Glu128 , also causes disease when mutated; mutation E128K is responsible for hyperinsulinism because it reduces KATP channel activity by interfering with proper trafficking of channels to the plasma membrane (16). Login to comment 125 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Because of the opposite pathological consequences of F132L and E128K mutations despite their proximity, it was interesting to also subject E128K to the Rho protection assay. Login to comment 126 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu Another residue of this short loop, Glu128 , also causes disease when mutated; mutation E128K is responsible for hyperinsulinism because it reduces KATP channel activity by interfering with proper trafficking of channels to the plasma membrane (16). Login to comment 127 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu Because of the opposite pathological consequences of F132L and E128K mutations despite their proximity, it was interesting to also subject E128K to the Rho protection assay. Login to comment 133 ABCC8 p.Phe132Leu As for the F132L mutation, we attempted to test the effect of the mutation E126A on TMD0 of SUR2A alone but were unable to record sufficient channel activity from oocytes co-expressing TMD0E126AϩKir6.2⌬C36, thus precluding any valid characterization. Login to comment 134 ABCC8 p.Phe132Leu As for the F132L mutation, we attempted to test the effect of the mutation E126A on TMD0 of SUR2A alone but were unable to record sufficient channel activity from oocytes co-expressing TMD0E126Aaf9;Kir6.2èc;C36, thus precluding any valid characterization. Login to comment 135 ABCC8 p.Phe132Leu As for the F132L mutation, we attempted to test the effect of the mutation E126A on TMD0 of SUR2A alone but were unable to record sufficient channel activity from oocytes co-expressing TMD0E126Aaf9;Kir6.2èc;C36, thus precluding any valid characterization. Login to comment 173 ABCC8 p.Phe132Leu The neonatal diabetes F132L mutation in SUR1 leads to a constitutive Rho-insensitive conformation, similar to that of the TMD0 ؉ Kir6.2 channel. Login to comment 174 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu A and B, currents recorded in inside-out patches from Xenopus oocytes co-expressing Kir6.2 and either wild-type SUR1 (A) or the F132L mutant (B). Login to comment 175 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu The neonatal diabetes F132L mutation in SUR1 leads to a constitutive Rho-insensitive conformation, similar to that of the TMD0 &#2d19; Kir6.2 channel. Login to comment 176 ABCC8 p.Phe132Leu A and B, currents recorded in inside-out patches from Xenopus oocytes co-expressing Kir6.2 and either wild-type SUR1 (A) or the F132L mutant (B). Login to comment 183 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu Structural Perturbations Induced by Disease-causing Mutations in the Second Intracellular Loop-Mutations F132L and E128K in short intracellular loop 2 located in TMD0 of SUR1 have opposite consequences. Login to comment 184 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu The neonatal diabetes F132L mutation reduces ATP sensitivity by augmenting open probability (23). Login to comment 185 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Structural Perturbations Induced by Disease-causing Mutations in the Second Intracellular Loop-Mutations F132L and E128K in short intracellular loop 2 located in TMD0 of SUR1 have opposite consequences. Login to comment 186 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu The hyperinsulinism E128K mutation disrupts channel trafficking and reduces channel function through poor surface expression (16). Login to comment 187 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu After rescue to the cell surface by a chemical chaperone, the E128K mutant channels are hyperactive with a lower than normal ATP sensitivity like the F132L mutants, although they exhibit an abnormally low Po (25). Login to comment 188 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu The F132L and E128K mutations cause therefore an abnormally high activity through different mechanisms. Login to comment 189 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Pratt et al. (25) speculated that E128K caused functional uncoupling between SUR1 and Kir6.2, thus removing the hypersensitization to ATP brought about by SUR1 (18). Login to comment 190 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Based on co-immunoprecipitation of TMD0 alone and Kir6.2 showing that F132L impaired the association of TMD0 and Kir6.2, Proks et al. (23) assumed that TMD0 and SUR behaved identically and concluded that this mutation disconnects SUR from Kir6.2. Login to comment 191 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu Pratt et al. (25) speculated that E128K caused functional uncoupling between SUR1 and Kir6.2, thus removing the hypersensitization to ATP brought about by SUR1 (18). Login to comment 192 ABCC8 p.Phe132Leu Based on co-immunoprecipitation of TMD0 alone and Kir6.2 showing that F132L impaired the association of TMD0 and Kir6.2, Proks et al. (23) assumed that TMD0 and SUR behaved identically and concluded that this mutation disconnects SUR from Kir6.2. Login to comment 214 ABCC8 p.Phe132Leu This suggests that although the F132L and E126A mutations lock the TMD0-Kir6.2 interface in distinct conformations where the Rho-binding site is either always masked or always accessible, other regions of SUR are unaffected and can interact with Kir6.2 to modulate its gating. Login to comment 215 ABCC8 p.Phe132Leu This suggests that although the F132L and E126A mutations lock the TMD0-Kir6.2 interface in distinct conformations where the Rho-binding site is either always masked or always accessible, other regions of SUR are unaffected and can interact with Kir6.2 to modulate its gating. Login to comment 216 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Rho Protection Assay Unveils the Mechanism of Disease-causing Mutations-Even though the F132L and E128K mutations in SUR1 both tend to reduce channel sensitivity to ATP, their mechanisms of action obviously differ because F132L increases Po, and E128K decreases Po. Login to comment 217 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Nonetheless, after detailed investigation, Proks et al. (23) working on F132L and Pratt et al. (25) working on E128K reached identical conclusions: the mutation disrupts the coupling/interaction between TMD0 and Kir6.2. Login to comment 218 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu The additional insight obtained by the Rho protection assay appears to resolve this discrepancy as it strengthens the proposed mechanism for E128K while questioning that for F132L. Login to comment 219 ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Nonetheless, after detailed investigation, Proks et al. (23) working on F132L and Pratt et al. (25) working on E128K reached identical conclusions: the mutation disrupts the coupling/interaction between TMD0 and Kir6.2. Login to comment 220 ABCC8 p.Glu128Lys ABCC8 p.Phe132Leu The additional insight obtained by the Rho protection assay appears to resolve this discrepancy as it strengthens the proposed mechanism for E128K while questioning that for F132L. Login to comment 225 ABCC8 p.Phe132Leu This suggests that the conformation of TMD0 in all these cases: F132L, TMD0 alone, and activators, could be similar. Login to comment 226 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu Thus, the channel hyperactivity caused by the F132L mutation would reflect the stabilization of TMD0 in the same activated conformation that is triggered by activators. Login to comment 227 ABCC8 p.Phe132Leu ABCC8 p.Phe132Leu This suggests that the conformation of TMD0 in all these cases: F132L, TMD0 alone, and activators, could be similar. Login to comment 228 ABCC8 p.Phe132Leu Thus, the channel hyperactivity caused by the F132L mutation would reflect the stabilization of TMD0 in the same activated conformation that is triggered by activators. Login to comment